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Diffstat (limited to 'posix_users')
25 files changed, 11564 insertions, 1 deletions
diff --git a/posix_users/clock.rst b/posix_users/clock.rst new file mode 100644 index 0000000..f37c1b9 --- /dev/null +++ b/posix_users/clock.rst @@ -0,0 +1,323 @@ +Clock Manager +############# + +Introduction +============ + +The clock manager provides services two primary classes +of services. The first focuses on obtaining and setting +the current date and time. The other category of services +focus on allowing a thread to delay for a specific length +of time. + +The directives provided by the clock manager are: + +- ``clock_gettime`` - Obtain Time of Day + +- ``clock_settime`` - Set Time of Day + +- ``clock_getres`` - Get Clock Resolution + +- ``sleep`` - Delay Process Execution + +- ``usleep`` - Delay Process Execution in Microseconds + +- ``nanosleep`` - Delay with High Resolution + +- ``gettimeofday`` - Get the Time of Day + +- ``time`` - Get time in seconds + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the clock manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +clock_gettime - Obtain Time of Day +---------------------------------- +.. index:: clock_gettime +.. index:: obtain time of day + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int clock_gettime( + clockid_t clock_id, + struct timespec \*tp + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets errno to one of the following: + +*EINVAL* + The tp pointer parameter is invalid. + +*EINVAL* + The clock_id specified is invalid. + +**DESCRIPTION:** + +**NOTES:** + +NONE + +clock_settime - Set Time of Day +------------------------------- +.. index:: clock_settime +.. index:: set time of day + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int clock_settime( + clockid_t clock_id, + const struct timespec \*tp + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets errno to one of the following: + +*EINVAL* + The tp pointer parameter is invalid. + +*EINVAL* + The clock_id specified is invalid. + +*EINVAL* + The contents of the tp structure are invalid. + +**DESCRIPTION:** + +**NOTES:** + +NONE + +clock_getres - Get Clock Resolution +----------------------------------- +.. index:: clock_getres +.. index:: get clock resolution + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int clock_getres( + clockid_t clock_id, + struct timespec \*res + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets errno to one of the following: + +*EINVAL* + The res pointer parameter is invalid. + +*EINVAL* + The clock_id specified is invalid. + +**DESCRIPTION:** + +**NOTES:** + +If res is NULL, then the resolution is not returned. + +sleep - Delay Process Execution +------------------------------- +.. index:: sleep +.. index:: delay process execution + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + unsigned int sleep( + unsigned int seconds + ); + +**STATUS CODES:** + +This routine returns the number of unslept seconds. + +**DESCRIPTION:** + +The ``sleep()`` function delays the calling thread by the specified +number of ``seconds``. + +**NOTES:** + +This call is interruptible by a signal. + +usleep - Delay Process Execution in Microseconds +------------------------------------------------ +.. index:: usleep +.. index:: delay process execution +.. index:: delay process execution +.. index:: usecs delay process execution +.. index:: microsecond delay process execution + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + useconds_t usleep( + useconds_t useconds + ); + +**STATUS CODES:** + +This routine returns the number of unslept seconds. + +**DESCRIPTION:** + +The ``sleep()`` function delays the calling thread by the specified +number of ``seconds``. + +The ``usleep()`` function suspends the calling thread from execution +until either the number of microseconds specified by the``useconds`` argument has elapsed or a signal is delivered to the +calling thread and its action is to invoke a signal-catching function +or to terminate the process. + +Because of other activity, or because of the time spent in +processing the call, the actual length of time the thread is +blocked may be longer than +the amount of time specified. + +**NOTES:** + +This call is interruptible by a signal. + +The Single UNIX Specification allows this service to be implemented using +the same timer as that used by the ``alarm()`` service. This is*NOT* the case for *RTEMS* and this call has no interaction with +the ``SIGALRM`` signal. + +nanosleep - Delay with High Resolution +-------------------------------------- +.. index:: nanosleep +.. index:: delay with high resolution + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int nanosleep( + const struct timespec \*rqtp, + struct timespec \*rmtp + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets errno to one of the following: + +*EINTR* + The routine was interrupted by a signal. + +*EAGAIN* + The requested sleep period specified negative seconds or nanoseconds. + +*EINVAL* + The requested sleep period specified an invalid number for the nanoseconds + field. + +**DESCRIPTION:** + +**NOTES:** + +This call is interruptible by a signal. + +gettimeofday - Get the Time of Day +---------------------------------- +.. index:: gettimeofday +.. index:: get the time of day + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/time.h> + #include <unistd.h> + int gettimeofday( + struct timeval \*tp, + struct timezone \*tzp + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets ``errno`` as appropriate. + +*EPERM* + ``settimeofdat`` is called by someone other than the superuser. + +*EINVAL* + Timezone (or something else) is invalid. + +*EFAULT* + One of ``tv`` or ``tz`` pointed outside your accessible address + space + +**DESCRIPTION:** + +This routine returns the current time of day in the ``tp`` structure. + +**NOTES:** + +Currently, the timezone information is not supported. The ``tzp`` +argument is ignored. + +time - Get time in seconds +-------------------------- +.. index:: time +.. index:: get time in seconds + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int time( + time_t \*tloc + ); + +**STATUS CODES:** + +This routine returns the number of seconds since the Epoch. + +**DESCRIPTION:** + +``time`` returns the time since 00:00:00 GMT, January 1, 1970, +measured in seconds + +If ``tloc`` in non null, the return value is also stored in the +memory pointed to by ``t``. + +**NOTES:** + +NONE + +.. COMMENT: This is the chapter from the RTEMS POSIX 1003.1b API User's Guide that + +.. COMMENT: documents the services provided by the timer @c manager. + diff --git a/posix_users/command.rst b/posix_users/command.rst new file mode 100644 index 0000000..99acf64 --- /dev/null +++ b/posix_users/command.rst @@ -0,0 +1,5 @@ +Command and Variable Index +########################## + +.. COMMENT: There are currently no Command and Variable Index entries. + diff --git a/posix_users/condition_variable.rst b/posix_users/condition_variable.rst new file mode 100644 index 0000000..35bd3ad --- /dev/null +++ b/posix_users/condition_variable.rst @@ -0,0 +1,320 @@ +Condition Variable Manager +########################## + +Introduction +============ + +The condition variable manager ... + +The directives provided by the condition variable manager are: + +- ``pthread_condattr_init`` - Initialize a Condition Variable Attribute Set + +- ``pthread_condattr_destroy`` - Destroy a Condition Variable Attribute Set + +- ``pthread_condattr_setpshared`` - Set Process Shared Attribute + +- ``pthread_condattr_getpshared`` - Get Process Shared Attribute + +- ``pthread_cond_init`` - Initialize a Condition Variable + +- ``pthread_cond_destroy`` - Destroy a Condition Variable + +- ``pthread_cond_signal`` - Signal a Condition Variable + +- ``pthread_cond_broadcast`` - Broadcast a Condition Variable + +- ``pthread_cond_wait`` - Wait on a Condition Variable + +- ``pthread_cond_timedwait`` - With with Timeout a Condition Variable + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the condition variable manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +pthread_condattr_init - Initialize a Condition Variable Attribute Set +--------------------------------------------------------------------- +.. index:: pthread_condattr_init +.. index:: initialize a condition variable attribute set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_condattr_init( + pthread_condattr_t \*attr + ); + +**STATUS CODES:** + +*ENOMEM* + Insufficient memory is available to initialize the condition variable + attributes object. + +**DESCRIPTION:** + +**NOTES:** + +pthread_condattr_destroy - Destroy a Condition Variable Attribute Set +--------------------------------------------------------------------- +.. index:: pthread_condattr_destroy +.. index:: destroy a condition variable attribute set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_condattr_destroy( + pthread_condattr_t \*attr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute object specified is invalid. + +**DESCRIPTION:** + +**NOTES:** + +pthread_condattr_setpshared - Set Process Shared Attribute +---------------------------------------------------------- +.. index:: pthread_condattr_setpshared +.. index:: set process shared attribute + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_condattr_setpshared( + pthread_condattr_t \*attr, + int pshared + ); + +**STATUS CODES:** + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +**NOTES:** + +pthread_condattr_getpshared - Get Process Shared Attribute +---------------------------------------------------------- +.. index:: pthread_condattr_getpshared +.. index:: get process shared attribute + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_condattr_getpshared( + const pthread_condattr_t \*attr, + int \*pshared + ); + +**STATUS CODES:** + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +**NOTES:** + +pthread_cond_init - Initialize a Condition Variable +--------------------------------------------------- +.. index:: pthread_cond_init +.. index:: initialize a condition variable + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_cond_init( + pthread_cond_t \*cond, + const pthread_condattr_t \*attr + ); + +**STATUS CODES:** + +*EAGAIN* + The system lacked a resource other than memory necessary to create the + initialize the condition variable object. + +*ENOMEM* + Insufficient memory is available to initialize the condition variable object. + +*EBUSY* + The specified condition variable has already been initialized. + +*EINVAL* + The specified attribute value is invalid. + +**DESCRIPTION:** + +**NOTES:** + +pthread_cond_destroy - Destroy a Condition Variable +--------------------------------------------------- +.. index:: pthread_cond_destroy +.. index:: destroy a condition variable + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_cond_destroy( + pthread_cond_t \*cond + ); + +**STATUS CODES:** + +*EINVAL* + The specified condition variable is invalid. + +*EBUSY* + The specified condition variable is currently in use. + +**DESCRIPTION:** + +**NOTES:** + +pthread_cond_signal - Signal a Condition Variable +------------------------------------------------- +.. index:: pthread_cond_signal +.. index:: signal a condition variable + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_cond_signal( + pthread_cond_t \*cond + ); + +**STATUS CODES:** + +*EINVAL* + The specified condition variable is not valid. + +**DESCRIPTION:** + +**NOTES:** + +This routine should not be invoked from a handler from an asynchronous signal +handler or an interrupt service routine. + +pthread_cond_broadcast - Broadcast a Condition Variable +------------------------------------------------------- +.. index:: pthread_cond_broadcast +.. index:: broadcast a condition variable + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_cond_broadcast( + pthread_cond_t \*cond + ); + +**STATUS CODES:** + +*EINVAL* + The specified condition variable is not valid. + +**DESCRIPTION:** + +**NOTES:** + +This routine should not be invoked from a handler from an asynchronous signal +handler or an interrupt service routine. + +pthread_cond_wait - Wait on a Condition Variable +------------------------------------------------ +.. index:: pthread_cond_wait +.. index:: wait on a condition variable + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_cond_wait( + pthread_cond_t \*cond, + pthread_mutex_t \*mutex + ); + +**STATUS CODES:** + +*EINVAL* + The specified condition variable or mutex is not initialized OR different + mutexes were specified for concurrent pthread_cond_wait() and + pthread_cond_timedwait() operations on the same condition variable OR + the mutex was not owned by the current thread at the time of the call. + +**DESCRIPTION:** + +**NOTES:** + +pthread_cond_timedwait - Wait with Timeout a Condition Variable +--------------------------------------------------------------- +.. index:: pthread_cond_timedwait +.. index:: wait with timeout a condition variable + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_cond_timedwait( + pthread_cond_t \*cond, + pthread_mutex_t \*mutex, + const struct timespec \*abstime + ); + +**STATUS CODES:** + +*EINVAL* + The specified condition variable or mutex is not initialized OR different + mutexes were specified for concurrent pthread_cond_wait() and + pthread_cond_timedwait() operations on the same condition variable OR + the mutex was not owned by the current thread at the time of the call. + +*ETIMEDOUT* + The specified time has elapsed without the condition variable being + satisfied. + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/device_and_class_specific.rst b/posix_users/device_and_class_specific.rst new file mode 100644 index 0000000..b2dda8c --- /dev/null +++ b/posix_users/device_and_class_specific.rst @@ -0,0 +1,411 @@ +Device- and Class- Specific Functions Manager +############################################# + +Introduction +============ + +The device- and class- specific functions manager is ... + +The directives provided by the device- and class- specific functions +manager are: + +- ``cfgetispeed`` - Reads terminal input baud rate + +- ``cfgetospeed`` - Reads terminal output baud rate + +- ``cfsetispeed`` - Sets terminal input baud rate + +- ``cfsetospeed`` - Set terminal output baud rate + +- ``tcgetattr`` - Gets terminal attributes + +- ``tcsetattr`` - Set terminal attributes + +- ``tcsendbreak`` - Sends a break to a terminal + +- ``tcdrain`` - Waits for all output to be transmitted to the terminal + +- ``tcflush`` - Discards terminal data + +- ``tcflow`` - Suspends/restarts terminal output + +- ``tcgetpgrp`` - Gets foreground process group ID + +- ``tcsetpgrp`` - Sets foreground process group ID + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the device- and class- specific functions manager’s +directives. A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +cfgetispeed - Reads terminal input baud rate +-------------------------------------------- +.. index:: cfgetispeed +.. index:: reads terminal input baud rate + +**CALLING SEQUENCE:** + +.. code:: c + + #include <termios.h> + int cfgetispeed( + const struct termios \*p + ); + +**STATUS CODES:** + +The ``cfgetispeed()`` function returns a code for baud rate. + +**DESCRIPTION:** + +The ``cfsetispeed()`` function stores a code for the terminal speed +stored in a struct termios. The codes are defined in ``<termios.h>`` +by the macros BO, B50, B75, B110, B134, B150, B200, B300, B600, B1200, +B1800, B2400, B4800, B9600, B19200, and B38400. + +The ``cfsetispeed()`` function does not do anything to the hardware. +It merely stores a value for use by ``tcsetattr()``. + +**NOTES:** + +Baud rates are defined by symbols, such as B110, B1200, B2400. The actual +number returned for any given speed may change from system to system. + +cfgetospeed - Reads terminal output baud rate +--------------------------------------------- +.. index:: cfgetospeed +.. index:: reads terminal output baud rate + +**CALLING SEQUENCE:** + +.. code:: c + + #include <termios.h> + int cfgetospeed( + const struct termios \*p + ); + +**STATUS CODES:** + +The ``cfgetospeed()`` function returns the termios code for the baud rate. + +**DESCRIPTION:** + +The ``cfgetospeed()`` function returns a code for the terminal speed +stored in a ``struct termios``. The codes are defined in ``<termios.h>`` +by the macros BO, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, +B2400, B4800, B9600, B19200, and B38400. + +The ``cfgetospeed()`` function does not do anything to the hardware. +It merely returns the value stored by a previous call to ``tcgetattr()``. + +**NOTES:** + +Baud rates are defined by symbols, such as B110, B1200, B2400. The actual +number returned for any given speed may change from system to system. + +cfsetispeed - Sets terminal input baud rate +------------------------------------------- +.. index:: cfsetispeed +.. index:: sets terminal input baud rate + +**CALLING SEQUENCE:** + +.. code:: c + + #include <termios.h> + int cfsetispeed( + struct termios \*p, + speed_t speed + ); + +**STATUS CODES:** + +The ``cfsetispeed()`` function returns a zero when successful and +returns -1 when an error occurs. + +**DESCRIPTION:** + +The ``cfsetispeed()`` function stores a code for the terminal speed +stored in a struct termios. The codes are defined in ``<termios.h>`` +by the macros B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, +B1800, B2400, B4800, B9600, B19200, and B38400. + +**NOTES:** + +This function merely stores a value in the ``termios`` structure. It +does not change the terminal speed until a ``tcsetattr()`` is done. +It does not detect impossible terminal speeds. + +cfsetospeed - Sets terminal output baud rate +-------------------------------------------- +.. index:: cfsetospeed +.. index:: sets terminal output baud rate + +**CALLING SEQUENCE:** + +.. code:: c + + #include <termios.h> + int cfsetospeed( + struct termios \*p, + speed_t speed + ); + +**STATUS CODES:** + +The ``cfsetospeed()`` function returns a zero when successful and +returns -1 when an error occurs. + +**DESCRIPTION:** + +The ``cfsetospeed()`` function stores a code for the terminal speed stored +in a struct ``termios``. The codes are defiined in ``<termios.h>`` by the +macros B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400, +B4800, B9600, B19200, and B38400. + +The ``cfsetospeed()`` function does not do anything to the hardware. It +merely stores a value for use by ``tcsetattr()``. + +**NOTES:** + +This function merely stores a value in the ``termios`` structure. +It does not change the terminal speed until a ``tcsetattr()`` is done. +It does not detect impossible terminal speeds. + +tcgetattr - Gets terminal attributes +------------------------------------ +.. index:: tcgetattr +.. index:: gets terminal attributes + +**CALLING SEQUENCE:** + +.. code:: c + + #include <termios.h> + #include <unistd.h> + int tcgetattr( + int fildes, + struct termios \*p + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor + +*ENOOTY* + Terminal control function attempted for a file that is not a terminal. + +**DESCRIPTION:** + +The ``tcgetattr()`` gets the parameters associated with the terminal +referred to by ``fildes`` and stores them into the ``termios()`` +structure pointed to by ``termios_p``. + +**NOTES:** + +NONE + +tcsetattr - Set terminal attributes +----------------------------------- +.. index:: tcsetattr +.. index:: set terminal attributes + +**CALLING SEQUENCE:** + +.. code:: c + + #include <termios.h> + #include <unistd.h> + int tcsetattr( + int fildes, + int options, + const struct termios \*tp + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +tcsendbreak - Sends a break to a terminal +----------------------------------------- +.. index:: tcsendbreak +.. index:: sends a break to a terminal + +**CALLING SEQUENCE:** + +.. code:: c + + int tcsendbreak( + int fd + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +tcdrain - Waits for all output to be transmitted to the terminal. +----------------------------------------------------------------- +.. index:: tcdrain +.. index:: waits for all output to be transmitted to the terminal. + +**CALLING SEQUENCE:** + +.. code:: c + + #include <termios.h> + #include <unistd.h> + int tcdrain( + int fildes + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor + +*EINTR* + Function was interrupted by a signal + +*ENOTTY* + Terminal control function attempted for a file that is not a terminal. + +**DESCRIPTION:** + +The ``tcdrain()`` function waits until all output written to``fildes`` has been transmitted. + +**NOTES:** + +NONE + +tcflush - Discards terminal data +-------------------------------- +.. index:: tcflush +.. index:: discards terminal data + +**CALLING SEQUENCE:** + +.. code:: c + + int tcflush( + int fd + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +tcflow - Suspends/restarts terminal output. +------------------------------------------- +.. index:: tcflow +.. index:: suspends/restarts terminal output. + +**CALLING SEQUENCE:** + +.. code:: c + + int tcflow( + int fd + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +tcgetpgrp - Gets foreground process group ID +-------------------------------------------- +.. index:: tcgetpgrp +.. index:: gets foreground process group id + +**CALLING SEQUENCE:** + +.. code:: c + + int tcgetpgrp( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +tcsetpgrp - Sets foreground process group ID +-------------------------------------------- +.. index:: tcsetpgrp +.. index:: sets foreground process group id + +**CALLING SEQUENCE:** + +.. code:: c + + int tcsetpgrp( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/files_and_directory.rst b/posix_users/files_and_directory.rst new file mode 100644 index 0000000..ea39ba3 --- /dev/null +++ b/posix_users/files_and_directory.rst @@ -0,0 +1,1947 @@ +Files and Directories Manager +############################# + +Introduction +============ + +The files and directories manager is ... + +The directives provided by the files and directories manager are: + +- ``opendir`` - Open a Directory + +- ``readdir`` - Reads a directory + +- ``rewinddir`` - Resets the ``readdir()`` pointer + +- ``scandir`` - Scan a directory for matching entries + +- ``telldir`` - Return current location in directory stream + +- ``closedir`` - Ends directory read operation + +- ``getdents`` - Get directory entries + +- ``chdir`` - Changes the current working directory + +- ``fchdir`` - Changes the current working directory + +- ``getcwd`` - Gets current working directory + +- ``open`` - Opens a file + +- ``creat`` - Create a new file or rewrite an existing one + +- ``umask`` - Sets a file creation mask + +- ``link`` - Creates a link to a file + +- ``symlink`` - Creates a symbolic link to a file + +- ``readlink`` - Obtain the name of the link destination + +- ``mkdir`` - Makes a directory + +- ``mkfifo`` - Makes a FIFO special file + +- ``unlink`` - Removes a directory entry + +- ``rmdir`` - Delete a directory + +- ``rename`` - Renames a file + +- ``stat`` - Gets information about a file. + +- ``fstat`` - Gets file status + +- ``lstat`` - Gets file status + +- ``access`` - Check permissions for a file. + +- ``chmod`` - Changes file mode + +- ``fchmod`` - Changes permissions of a file + +- ``chown`` - Changes the owner and/ or group of a file + +- ``utime`` - Change access and/or modification times of an inode + +- ``ftruncate`` - Truncate a file to a specified length + +- ``truncate`` - Truncate a file to a specified length + +- ``pathconf`` - Gets configuration values for files + +- ``fpathconf`` - Get configuration values for files + +- ``mknod`` - Create a directory + +Background +========== + +Path Name Evaluation +-------------------- + +A pathname is a string that consists of no more than ``PATH_MAX`` +bytes, including the terminating null character. A pathname has an optional +beginning slash, followed by zero or more filenames separated by slashes. +If the pathname refers to a directory, it may also have one or more trailing +slashes. Multiple successive slahes are considered to be the same as +one slash. + +POSIX allows a pathname that begins with precisely two successive slashes to be +interpreted in an implementation-defined manner. RTEMS does not currently +recognize this as a special condition. Any number of successive +slashes is treated the same as a single slash. POSIX requires that +an implementation treat more than two leading slashes as a single slash. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the files and directories manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +opendir - Open a Directory +-------------------------- +.. index:: opendir +.. index:: open a directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <dirent.h> + int opendir( + const char \*dirname + ); + +**STATUS CODES:** + +*EACCES* + Search permission was denied on a component of the path + prefix of ``dirname``, or read permission is denied + +*EMFILE* + Too many file descriptors in use by process + +*ENFILE* + Too many files are currently open in the system. + +*ENOENT* + Directory does not exist, or ``name`` is an empty string. + +*ENOMEM* + Insufficient memory to complete the operation. + +*ENOTDIR* + ``name`` is not a directory. + +**DESCRIPTION:** + +This routine opens a directory stream corresponding to the +directory specified by the ``dirname`` argument. The +directory stream is positioned at the first entry. + +**NOTES:** + +The routine is implemented in Cygnus newlib. + +readdir - Reads a directory +--------------------------- +.. index:: readdir +.. index:: reads a directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <dirent.h> + int readdir( + DIR \*dirp + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor + +**DESCRIPTION:** + +The ``readdir()`` function returns a pointer to a structure ``dirent`` +representing the next directory entry from the directory stream pointed to +by ``dirp``. On end-of-file, NULL is returned. + +The ``readdir()`` function may (or may not) return entries for . or .. Your +program should tolerate reading dot and dot-dot but not require them. + +The data pointed to be ``readdir()`` may be overwritten by another call to``readdir()`` for the same directory stream. It will not be overwritten by +a call for another directory. + +**NOTES:** + +If ``ptr`` is not a pointer returned by ``malloc()``, ``calloc()``, or``realloc()`` or has been deallocated with ``free()`` or``realloc()``, the results are not portable and are probably disastrous. + +The routine is implemented in Cygnus newlib. + +rewinddir - Resets the readdir() pointer +---------------------------------------- +.. index:: rewinddir +.. index:: resets the readdir() pointer + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <dirent.h> + void rewinddir( + DIR \*dirp + ); + +**STATUS CODES:** + +No value is returned. + +**DESCRIPTION:** + +The ``rewinddir()`` function resets the position associated with +the directory stream pointed to by ``dirp``. It also causes the +directory stream to refer to the current state of the directory. + +**NOTES:** + +NONE + +If ``dirp`` is not a pointer by ``opendir()``, the results are +undefined. + +The routine is implemented in Cygnus newlib. + +scandir - Scan a directory for matching entries +----------------------------------------------- +.. index:: scandir +.. index:: scan a directory for matching entries + +**CALLING SEQUENCE:** + +.. code:: c + + #include <dirent.h> + int scandir( + const char \*dir, + struct dirent \***namelist, + int (\*select)(const struct dirent \*), + int (\*compar)(const struct dirent \**, const struct dirent \**) + ); + +**STATUS CODES:** + +*ENOMEM* + Insufficient memory to complete the operation. + +**DESCRIPTION:** + +The ``scandir()`` function scans the directory ``dir``, calling``select()`` on each directory entry. Entries for which ``select()`` +returns non-zero are stored in strings allocated via ``malloc()``, +sorted using ``qsort()`` with the comparison function ``compar()``, +and collected in array ``namelist`` which is allocated via ``malloc()``. +If ``select`` is NULL, all entries are selected. + +**NOTES:** + +The routine is implemented in Cygnus newlib. + +telldir - Return current location in directory stream +----------------------------------------------------- +.. index:: telldir +.. index:: return current location in directory stream + +**CALLING SEQUENCE:** + +.. code:: c + + #include <dirent.h> + off_t telldir( + DIR \*dir + ); + +**STATUS CODES:** + +*EBADF* + Invalid directory stream descriptor ``dir``. + +**DESCRIPTION:** + +The ``telldir()`` function returns the current location associated with the +directory stream ``dir``. + +**NOTES:** + +The routine is implemented in Cygnus newlib. + +closedir - Ends directory read operation +---------------------------------------- +.. index:: closedir +.. index:: ends directory read operation + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <dirent.h> + int closedir( + DIR \*dirp + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor + +**DESCRIPTION:** + +The directory stream associated with ``dirp`` is closed. +The value in ``dirp`` may not be usable after a call to``closedir()``. + +**NOTES:** + +NONE + +The argument to ``closedir()`` must be a pointer returned by``opendir()``. If it is not, the results are not portable and +most likely unpleasant. + +The routine is implemented in Cygnus newlib. + +chdir - Changes the current working directory +--------------------------------------------- +.. index:: chdir +.. index:: changes the current working directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int chdir( + const char \*path + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets ``errno`` to one of +the following: + +*EACCES* + Search permission is denied for a directory in a file’s path prefix. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is + in effect. + +*ENOENT* + A file or directory does not exist. + +*ENOTDIR* + A component of the specified pathname was not a directory when directory + was expected. + +**DESCRIPTION:** + +The ``chdir()`` function causes the directory named by ``path`` to +become the current working directory; that is, the starting point for +searches of pathnames not beginning with a slash. + +If ``chdir()`` detects an error, the current working directory is not +changed. + +**NOTES:** + +NONE + +fchdir - Changes the current working directory +---------------------------------------------- +.. index:: fchdir +.. index:: changes the current working directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int fchdir( + int fd + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets ``errno`` to one of +the following: + +*EACCES* + Search permission is denied for a directory in a file’s path prefix. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is + in effect. + +*ENOENT* + A file or directory does not exist. + +*ENOTDIR* + A component of the specified pathname was not a directory when directory + was expected. + +**DESCRIPTION:** + +The ``fchdir()`` function causes the directory named by ``fd`` to +become the current working directory; that is, the starting point for +searches of pathnames not beginning with a slash. + +If ``fchdir()`` detects an error, the current working directory is not +changed. + +**NOTES:** + +NONE + +getcwd - Gets current working directory +--------------------------------------- +.. index:: getcwd +.. index:: gets current working directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int getcwd( void ); + +**STATUS CODES:** + +*EINVAL* + Invalid argument + +*ERANGE* + Result is too large + +*EACCES* + Search permission is denied for a directory in a file’s path prefix. + +**DESCRIPTION:** + +The ``getcwd()`` function copies the absolute pathname of the current +working directory to the character array pointed to by ``buf``. The``size`` argument is the number of bytes available in ``buf`` + +**NOTES:** + +There is no way to determine the maximum string length that ``fetcwd()`` +may need to return. Applications should tolerate getting ``ERANGE`` +and allocate a larger buffer. + +It is possible for ``getcwd()`` to return EACCES if, say, ``login`` +puts the process into a directory without read access. + +The 1988 standard uses ``int`` instead of ``size_t`` for the second +parameter. + +open - Opens a file +------------------- +.. index:: open +.. index:: opens a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + #include <fcntl.h> + int open( + const char \*path, + int oflag, + mode_t mode + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix. + +*EEXIST* + The named file already exists. + +*EINTR* + Function was interrupted by a signal. + +*EISDIR* + Attempt to open a directory for writing or to rename a file to be a + directory. + +*EMFILE* + Too many file descriptors are in use by this process. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENFILE* + Too many files are currently open in the system. + +*ENOENT* + A file or directory does not exist. + +*ENOSPC* + No space left on disk. + +*ENOTDIR* + A component of the specified pathname was not a directory when a directory + was expected. + +*ENXIO* + No such device. This error may also occur when a device is not ready, for + example, a tape drive is off-line. + +*EROFS* + Read-only file system. + +**DESCRIPTION:** + +The ``open`` function establishes a connection between a file and a file +descriptor. The file descriptor is a small integer that is used by I/O +functions to reference the file. The ``path`` argument points to the +pathname for the file. + +The ``oflag`` argument is the bitwise inclusive OR of the values of +symbolic constants. The programmer must specify exactly one of the following +three symbols: + +*O_RDONLY* + Open for reading only. + +*O_WRONLY* + Open for writing only. + +*O_RDWR* + Open for reading and writing. + +Any combination of the following symbols may also be used. + +*O_APPEND* + Set the file offset to the end-of-file prior to each write. + +*O_CREAT* + If the file does not exist, allow it to be created. This flag indicates + that the ``mode`` argument is present in the call to ``open``. + +*O_EXCL* + This flag may be used only if O_CREAT is also set. It causes the call + to ``open`` to fail if the file already exists. + +*O_NOCTTY* + If ``path`` identifies a terminal, this flag prevents that teminal from + becoming the controlling terminal for thi9s process. See Chapter 8 for a + description of terminal I/O. + +*O_NONBLOCK* + Do no wait for the device or file to be ready or available. After the file + is open, the ``read`` and ``write`` calls return immediately. If the + process would be delayed in the read or write opermation, -1 is returned and``errno`` is set to ``EAGAIN`` instead of blocking the caller. + +*O_TRUNC* + This flag should be used only on ordinary files opened for writing. It + causes the file to be tuncated to zero length.. + +Upon successful completion, ``open`` returns a non-negative file +descriptor. + +**NOTES:** + +NONE + +creat - Create a new file or rewrite an existing one +---------------------------------------------------- +.. index:: creat +.. index:: create a new file or rewrite an existing one + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + #include <fcntl.h> + int creat( + const char \*path, + mode_t mode + ); + +**STATUS CODES:** + +*EEXIST* + ``path`` already exists and O_CREAT and O_EXCL were used. + +*EISDIR* + ``path`` refers to a directory and the access requested involved + writing + +*ETXTBSY* + ``path`` refers to an executable image which is currently being + executed and write access was requested + +*EFAULT* + ``path`` points outside your accessible address space + +*EACCES* + The requested access to the file is not allowed, or one of the + directories in ``path`` did not allow search (execute) permission. + +*ENAMETOOLONG* + ``path`` was too long. + +*ENOENT* + A directory component in ``path`` does not exist or is a dangling + symbolic link. + +*ENOTDIR* + A component used as a directory in ``path`` is not, in fact, a + directory. + +*EMFILE* + The process alreadyh has the maximum number of files open. + +*ENFILE* + The limit on the total number of files open on the system has been + reached. + +*ENOMEM* + Insufficient kernel memory was available. + +*EROFS* + ``path`` refers to a file on a read-only filesystem and write access + was requested + +**DESCRIPTION:** + +``creat`` attempts to create a file and return a file descriptor for +use in read, write, etc. + +**NOTES:** + +NONE + +The routine is implemented in Cygnus newlib. + +umask - Sets a file creation mask. +---------------------------------- +.. index:: umask +.. index:: sets a file creation mask. + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + mode_t umask( + mode_t cmask + ); + +**STATUS CODES:** + +**DESCRIPTION:** + +The ``umask()`` function sets the process file creation mask to ``cmask``. +The file creation mask is used during ``open()``, ``creat()``, ``mkdir()``,``mkfifo()`` calls to turn off permission bits in the ``mode`` argument. +Bit positions that are set in ``cmask`` are cleared in the mode of the +created file. + +**NOTES:** + +NONE + +The ``cmask`` argument should have only permission bits set. All other +bits should be zero. + +In a system which supports multiple processes, the file creation mask is inherited +across ``fork()`` and ``exec()`` calls. This makes it possible to alter the +default permission bits of created files. RTEMS does not support multiple processes +so this behavior is not possible. + +link - Creates a link to a file +------------------------------- +.. index:: link +.. index:: creates a link to a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int link( + const char \*existing, + const char \*new + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*EEXIST* + The named file already exists. + +*EMLINK* + The number of links would exceed ``LINK_MAX``. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENOENT* + A file or directory does not exist. + +*ENOSPC* + No space left on disk. + +*ENOTDIR* + A component of the specified pathname was not a directory when a directory + was expected. + +*EPERM* + Operation is not permitted. Process does not have the appropriate priviledges + or permissions to perform the requested operations. + +*EROFS* + Read-only file system. + +*EXDEV* + Attempt to link a file to another file system. + +**DESCRIPTION:** + +The ``link()`` function atomically creates a new link for an existing file +and increments the link count for the file. + +If the ``link()`` function fails, no directories are modified. + +The ``existing`` argument should not be a directory. + +The caller may (or may not) need permission to access the existing file. + +**NOTES:** + +NONE + +symlink - Creates a symbolic link to a file +------------------------------------------- +.. index:: symlink +.. index:: creates a symbolic link to a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int symlink( + const char \*topath, + const char \*frompath + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*EEXIST* + The named file already exists. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENOENT* + A file or directory does not exist. + +*ENOSPC* + No space left on disk. + +*ENOTDIR* + A component of the specified pathname was not a directory when a directory + was expected. + +*EPERM* + Operation is not permitted. Process does not have the appropriate priviledges + or permissions to perform the requested operations. + +*EROFS* + Read-only file system. + +**DESCRIPTION:** + +The ``symlink()`` function creates a symbolic link from the frombath to the +topath. The symbolic link will be interpreted at run-time. + +If the ``symlink()`` function fails, no directories are modified. + +The caller may (or may not) need permission to access the existing file. + +**NOTES:** + +NONE + +readlink - Obtain the name of a symbolic link destination +--------------------------------------------------------- +.. index:: readlink +.. index:: obtain the name of a symbolic link destination + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int readlink( + const char \*path, + char \*buf, + size_t bufsize + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENOENT* + A file or directory does not exist. + +*ENOTDIR* + A component of the prefix pathname was not a directory when a directory + was expected. + +*ELOOP* + Too many symbolic links were encountered in the pathname. + +*EINVAL* + The pathname does not refer to a symbolic link + +*EFAULT* + An invalid pointer was passed into the ``readlink()`` routine. + +**DESCRIPTION:** + +The ``readlink()`` function places the symbolic link destination into``buf`` argument and returns the number of characters copied. + +If the symbolic link destination is longer than bufsize characters the +name will be truncated. + +**NOTES:** + +NONE + +mkdir - Makes a directory +------------------------- +.. index:: mkdir +.. index:: makes a directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + int mkdir( + const char \*path, + mode_t mode + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*EEXIST* + The name file already exist. + +*EMLINK* + The number of links would exceed LINK_MAX + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENOENT* + A file or directory does not exist. + +*ENOSPC* + No space left on disk. + +*ENOTDIR* + A component of the specified pathname was not a directory when a directory + was expected. + +*EROFS* + Read-only file system. + +**DESCRIPTION:** + +The ``mkdir()`` function creates a new diectory named ``path``. The +permission bits (modified by the file creation mask) are set from ``mode``. +The owner and group IDs for the directory are set from the effective user ID +and group ID. + +The new directory may (or may not) contain entries for.. and .. but is otherwise +empty. + +**NOTES:** + +NONE + +mkfifo - Makes a FIFO special file +---------------------------------- +.. index:: mkfifo +.. index:: makes a fifo special file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + int mkfifo( + const char \*path, + mode_t mode + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*EEXIST* + The named file already exists. + +*ENOENT* + A file or directory does not exist. + +*ENOSPC* + No space left on disk. + +*ENOTDIR* + A component of the specified ``path`` was not a directory when a directory + was expected. + +*EROFS* + Read-only file system. + +**DESCRIPTION:** + +The ``mkfifo()`` function creates a new FIFO special file named ``path``. +The permission bits (modified by the file creation mask) are set from``mode``. The owner and group IDs for the FIFO are set from the efective +user ID and group ID. + +**NOTES:** + +NONE + +unlink - Removes a directory entry +---------------------------------- +.. index:: unlink +.. index:: removes a directory entry + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int unlink( + const char path + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*EBUSY* + The directory is in use. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENOENT* + A file or directory does not exist. + +*ENOTDIR* + A component of the specified ``path`` was not a directory when a directory + was expected. + +*EPERM* + Operation is not permitted. Process does not have the appropriate priviledges + or permissions to perform the requested operations. + +*EROFS* + Read-only file system. + +**DESCRIPTION:** + +The ``unlink`` function removes the link named by ``path`` and decrements the +link count of the file referenced by the link. When the link count goes to zero +and no process has the file open, the space occupied by the file is freed and the +file is no longer accessible. + +**NOTES:** + +NONE + +rmdir - Delete a directory +-------------------------- +.. index:: rmdir +.. index:: delete a directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int rmdir( + const char \*pathname + ); + +**STATUS CODES:** + +*EPERM* + The filesystem containing ``pathname`` does not support the removal + of directories. + +*EFAULT* + ``pathname`` points ouside your accessible address space. + +*EACCES* + Write access to the directory containing ``pathname`` was not + allowed for the process’s effective uid, or one of the directories in``pathname`` did not allow search (execute) permission. + +*EPERM* + The directory containing ``pathname`` has the stickybit (S_ISVTX) + set and the process’s effective uid is neither the uid of the file to + be delected nor that of the director containing it. + +*ENAMETOOLONG* + ``pathname`` was too long. + +*ENOENT* + A dirctory component in ``pathname`` does not exist or is a + dangling symbolic link. + +*ENOTDIR* + ``pathname``, or a component used as a directory in ``pathname``, + is not, in fact, a directory. + +*ENOTEMPTY* + ``pathname`` contains entries other than . and .. . + +*EBUSY* + ``pathname`` is the current working directory or root directory of + some process + +*EBUSY* + ``pathname`` is the current directory or root directory of some + process. + +*ENOMEM* + Insufficient kernel memory was available + +*EROGS* + ``pathname`` refers to a file on a read-only filesystem. + +*ELOOP* + ``pathname`` contains a reference to a circular symbolic link + +**DESCRIPTION:** + +``rmdir`` deletes a directory, which must be empty + +**NOTES:** + +NONE + +rename - Renames a file +----------------------- +.. index:: rename +.. index:: renames a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int rename( + const char \*old, + const char \*new + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix. + +*EBUSY* + The directory is in use. + +*EEXIST* + The named file already exists. + +*EINVAL* + Invalid argument. + +*EISDIR* + Attempt to open a directory for writing or to rename a file to be a + directory. + +*EMLINK* + The number of links would exceed LINK_MAX. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is + in effect. + +*ENOENT* + A file or directory does no exist. + +*ENOSPC* + No space left on disk. + +*ENOTDIR* + A component of the specified pathname was not a directory when a + directory was expected. + +*ENOTEMPTY* + Attempt to delete or rename a non-empty directory. + +*EROFS* + Read-only file system + +*EXDEV* + Attempt to link a file to another file system. + +**DESCRIPTION:** + +The ``rename()`` function causes the file known bo ``old`` to +now be known as ``new``. + +Ordinary files may be renamed to ordinary files, and directories may be +renamed to directories; however, files cannot be converted using``rename()``. The ``new`` pathname may not contain a path prefix +of ``old``. + +**NOTES:** + +If a file already exists by the name ``new``, it is removed. The``rename()`` function is atomic. If the ``rename()`` detects an +error, no files are removed. This guarantees that the``rename("x", "x")`` does not remove ``x``. + +You may not rename dot or dot-dot. + +The routine is implemented in Cygnus newlib using ``link()`` and``unlink()``. + +stat - Gets information about a file +------------------------------------ +.. index:: stat +.. index:: gets information about a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + int stat( + const char \*path, + struct stat \*buf + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix. + +*EBADF* + Invalid file descriptor. + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is + in effect. + +*ENOENT* + A file or directory does not exist. + +*ENOTDIR* + A component of the specified pathname was not a directory when a + directory was expected. + +**DESCRIPTION:** + +The ``path`` argument points to a pathname for a file. Read, write, or +execute permission for the file is not required, but all directories listed +in ``path`` must be searchable. The ``stat()`` function obtains +information about the named file and writes it to the area pointed to by``buf``. + +**NOTES:** + +NONE + +fstat - Gets file status +------------------------ +.. index:: fstat +.. index:: gets file status + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + int fstat( + int fildes, + struct stat \*buf + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor + +**DESCRIPTION:** + +The ``fstat()`` function obtains information about the file +associated with ``fildes`` and writes it to the area pointed +to by the ``buf`` argument. + +**NOTES:** + +If the filesystem object referred to by ``fildes`` is a +link, then the information returned in ``buf`` refers +to the destination of that link. This is in contrast to``lstat()`` which does not follow the link. + +lstat - Gets file status +------------------------ +.. index:: lstat +.. index:: gets file status + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + int lstat( + int fildes, + struct stat \*buf + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor + +**DESCRIPTION:** + +The ``lstat()`` function obtains information about the file +associated with ``fildes`` and writes it to the area pointed +to by the ``buf`` argument. + +**NOTES:** + +If the filesystem object referred to by ``fildes`` is a +link, then the information returned in ``buf`` refers +to the link itself. This is in contrast to ``fstat()`` +which follows the link. + +The ``lstat()`` routine is defined by BSD 4.3 and SVR4 +and not included in POSIX 1003.1b-1996. + +access - Check permissions for a file +------------------------------------- +.. index:: access +.. index:: check permissions for a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int access( + const char \*pathname, + int mode + ); + +**STATUS CODES:** + +*EACCES* + The requested access would be denied, either to the file itself or + one of the directories in ``pathname``. + +*EFAULT* + ``pathname`` points outside your accessible address space. + +*EINVAL* + ``Mode`` was incorrectly specified. + +*ENAMETOOLONG* + ``pathname`` is too long. + +*ENOENT* + A directory component in ``pathname`` would have been accessible but + does not exist or was a dangling symbolic link. + +*ENOTDIR* + A component used as a directory in ``pathname`` is not, in fact, + a directory. + +*ENOMEM* + Insufficient kernel memory was available. + +**DESCRIPTION:** + +``Access`` checks whether the process would be allowed to read, write or +test for existence of the file (or other file system object) whose name is``pathname``. If ``pathname`` is a symbolic link permissions of the +file referred by this symbolic link are tested. + +``Mode`` is a mask consisting of one or more of R_OK, W_OK, X_OK and F_OK. + +**NOTES:** + +NONE + +chmod - Changes file mode. +-------------------------- +.. index:: chmod +.. index:: changes file mode. + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + int chmod( + const char \*path, + mode_t mode + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENOENT* + A file or directory does not exist. + +*ENOTDIR* + A component of the specified pathname was not a directory when a directory + was expected. + +*EPERM* + Operation is not permitted. Process does not have the appropriate priviledges + or permissions to perform the requested operations. + +*EROFS* + Read-only file system. + +**DESCRIPTION:** + +Set the file permission bits, the set user ID bit, and the set group ID bit +for the file named by ``path`` to ``mode``. If the effective user ID +does not match the owner of the file and the calling process does not have +the appropriate privileges, ``chmod()`` returns -1 and sets ``errno`` to``EPERM``. + +**NOTES:** + +NONE + +fchmod - Changes permissions of a file +-------------------------------------- +.. index:: fchmod +.. index:: changes permissions of a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/stat.h> + int fchmod( + int fildes, + mode_t mode + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix. + +*EBADF* + The descriptor is not valid. + +*EFAULT* + ``path`` points outside your accessible address space. + +*EIO* + A low-level I/o error occurred while modifying the inode. + +*ELOOP* + ``path`` contains a circular reference + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is + in effect. + +*ENOENT* + A file or directory does no exist. + +*ENOMEM* + Insufficient kernel memory was avaliable. + +*ENOTDIR* + A component of the specified pathname was not a directory when a + directory was expected. + +*EPERM* + The effective UID does not match the owner of the file, and is not + zero + +*EROFS* + Read-only file system + +**DESCRIPTION:** + +The mode of the file given by ``path`` or referenced by``filedes`` is changed. + +**NOTES:** + +NONE + +getdents - Get directory entries +-------------------------------- +.. index:: getdents +.. index:: get directory entries + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + #include <linux/dirent.h> + #include <linux/unistd.h> + long getdents( + int dd_fd, + char \*dd_buf, + int dd_len + ); + +**STATUS CODES:** + +A successful call to ``getdents`` returns th the number of bytes read. +On end of directory, 0 is returned. When an error occurs, -1 is returned, +and ``errno`` is set appropriately. + +*EBADF* + Invalid file descriptor ``fd``. + +*EFAULT* + Argument points outside the calling process’s address space. + +*EINVAL* + Result buffer is too small. + +*ENOENT* + No such directory. + +*ENOTDIR* + File descriptor does not refer to a directory. + +**DESCRIPTION:** + +``getdents`` reads several ``dirent`` structures from the directory +pointed by ``fd`` into the memory area pointed to by ``dirp``. The +parameter ``count`` is the size of the memory area. + +**NOTES:** + +NONE + +chown - Changes the owner and/or group of a file. +------------------------------------------------- +.. index:: chown +.. index:: changes the owner and/or group of a file. + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <unistd.h> + int chown( + const char \*path, + uid_t owner, + gid_t group + ); + +**STATUS CODES:** + +*EACCES* + Search permission is denied for a directory in a file’s path prefix + +*EINVAL* + Invalid argument + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC is in + effect. + +*ENOENT* + A file or directory does not exist. + +*ENOTDIR* + A component of the specified pathname was not a directory when a directory + was expected. + +*EPERM* + Operation is not permitted. Process does not have the appropriate priviledges + or permissions to perform the requested operations. + +*EROFS* + Read-only file system. + +**DESCRIPTION:** + +The user ID and group ID of the file named by ``path`` are set to``owner`` and ``path``, respectively. + +For regular files, the set group ID (S_ISGID) and set user ID (S_ISUID) +bits are cleared. + +Some systems consider it a security violation to allow the owner of a file to +be changed, If users are billed for disk space usage, loaning a file to +another user could result in incorrect billing. The ``chown()`` function +may be restricted to privileged users for some or all files. The group ID can +still be changed to one of the supplementary group IDs. + +**NOTES:** + +This function may be restricted for some file. The ``pathconf`` function +can be used to test the ``_PC_CHOWN_RESTRICTED`` flag. + +utime - Change access and/or modification times of an inode +----------------------------------------------------------- +.. index:: utime +.. index:: change access and/or modification times of an inode + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + int utime( + const char \*filename, + struct utimbuf \*buf + ); + +**STATUS CODES:** + +*EACCES* + Permission to write the file is denied + +*ENOENT* + ``Filename`` does not exist + +**DESCRIPTION:** + +``Utime`` changes the access and modification times of the inode +specified by ``filename`` to the ``actime`` and ``modtime`` +fields of ``buf`` respectively. If ``buf`` is NULL, then the +access and modification times of the file are set to the current time. + +**NOTES:** + +NONE + +ftruncate - truncate a file to a specified length +------------------------------------------------- +.. index:: ftruncate +.. index:: truncate a file to a specified length + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int ftrunctate( + int fd, + size_t length + ); + +**STATUS CODES:** + +*ENOTDIR* + A component of the path prefix is not a directory. + +*EINVAL* + The pathname contains a character with the high-order bit set. + +*ENAMETOOLONG* + A component of a pathname exceeded 255 characters, or an entire + path name exceeded 1023 characters. + +*ENOENT* + The named file does not exist. + +*EACCES* + The named file is not writable by the user. + +*EACCES* + Search permission is denied for a component of the path prefix. + +*ELOOP* + Too many symbolic links were encountered in translating the + pathname + +*EISDIR* + The named file is a directory. + +*EROFS* + The named file resides on a read-only file system + +*ETXTBSY* + The file is a pure procedure (shared text) file that is being + executed + +*EIO* + An I/O error occurred updating the inode. + +*EFAULT* + ``Path`` points outside the process’s allocated address space. + +*EBADF* + The ``fd`` is not a valid descriptor. + +**DESCRIPTION:** + +``truncate()`` causes the file named by ``path`` or referenced by``fd`` to be truncated to at most ``length`` bytes in size. If the +file previously was larger than this size, the extra data is lost. With``ftruncate()``, the file must be open for writing. + +**NOTES:** + +NONE + +truncate - truncate a file to a specified length +------------------------------------------------ +.. index:: truncate +.. index:: truncate a file to a specified length + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int trunctate( + const char \*path, + size_t length + ); + +**STATUS CODES:** + +*ENOTDIR* + A component of the path prefix is not a directory. + +*EINVAL* + The pathname contains a character with the high-order bit set. + +*ENAMETOOLONG* + A component of a pathname exceeded 255 characters, or an entire + path name exceeded 1023 characters. + +*ENOENT* + The named file does not exist. + +*EACCES* + The named file is not writable by the user. + +*EACCES* + Search permission is denied for a component of the path prefix. + +*ELOOP* + Too many symbolic links were encountered in translating the + pathname + +*EISDIR* + The named file is a directory. + +*EROFS* + The named file resides on a read-only file system + +*ETXTBSY* + The file is a pure procedure (shared text) file that is being + executed + +*EIO* + An I/O error occurred updating the inode. + +*EFAULT* + ``Path`` points outside the process’s allocated address space. + +*EBADF* + The ``fd`` is not a valid descriptor. + +**DESCRIPTION:** + +``truncate()`` causes the file named by ``path`` or referenced by``fd`` to be truncated to at most ``length`` bytes in size. If the +file previously was larger than this size, the extra data is lost. With``ftruncate()``, the file must be open for writing. + +**NOTES:** + +NONE + +pathconf - Gets configuration values for files +---------------------------------------------- +.. index:: pathconf +.. index:: gets configuration values for files + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int pathconf( + const char \*path, + int name + ); + +**STATUS CODES:** + +*EINVAL* + Invalid argument + +*EACCES* + Permission to write the file is denied + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC + is in effect. + +*ENOENT* + A file or directory does not exist + +*ENOTDIR* + A component of the specified ``path`` was not a directory whan a + directory was expected. + +**DESCRIPTION:** + +``pathconf()`` gets a value for the configuration option ``name`` +for the open file descriptor ``filedes``. + +The possible values for ``name`` are: + +*_PC_LINK_MAX* + returns the maximum number of links to the file. If ``filedes`` or``path`` refer to a directory, then the value applies to the whole + directory. The corresponding macro is ``_POSIX_LINK_MAX``. + +*_PC_MAX_CANON* + returns the maximum length of a formatted input line, where ``filedes`` + or ``path`` must refer to a terminal. The corresponding macro is``_POSIX_MAX_CANON``. + +*_PC_MAX_INPUT* + returns the maximum length of an input line, where ``filedes`` or``path`` must refer to a terminal. The corresponding macro is``_POSIX_MAX_INPUT``. + +*_PC_NAME_MAX* + returns the maximum length of a filename in the directory ``path`` or``filedes``. The process is allowed to create. The corresponding macro + is ``_POSIX_NAME_MAX``. + +*_PC_PATH_MAX* + returns the maximum length of a relative pathname when ``path`` or``filedes`` is the current working directory. The corresponding macro + is ``_POSIX_PATH_MAX``. + +*_PC_PIPE_BUF* + returns the size of the pipe buffer, where ``filedes`` must refer to a + pipe or FIFO and ``path`` must refer to a FIFO. The corresponding macro + is ``_POSIX_PIPE_BUF``. + +*_PC_CHOWN_RESTRICTED* + returns nonzero if the chown(2) call may not be used on this file. If``filedes`` or ``path`` refer to a directory, then this applies to all + files in that directory. The corresponding macro is``_POSIX_CHOWN_RESTRICTED``. + +**NOTES:** + +Files with name lengths longer than the value returned for ``name`` equal``_PC_NAME_MAX`` may exist in the given directory. + +fpathconf - Gets configuration values for files +----------------------------------------------- +.. index:: fpathconf +.. index:: gets configuration values for files + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int fpathconf( + int filedes, + int name + ); + +**STATUS CODES:** + +*EINVAL* + Invalid argument + +*EACCES* + Permission to write the file is denied + +*ENAMETOOLONG* + Length of a filename string exceeds PATH_MAX and _POSIX_NO_TRUNC + is in effect. + +*ENOENT* + A file or directory does not exist + +*ENOTDIR* + A component of the specified ``path`` was not a directory whan a + directory was expected. + +**DESCRIPTION:** + +``pathconf()`` gets a value for the configuration option ``name`` +for the open file descriptor ``filedes``. + +The possible values for name are: + +*_PC_LINK_MAX* + returns the maximum number of links to the file. If ``filedes`` or``path`` refer to a directory, then the value applies to the whole + directory. The corresponding macro is _POSIX_LINK_MAX. + +*_PC_MAX_CANON* + returns the maximum length of a formatted input line, where ``filedes`` + or ``path`` must refer to a terminal. The corresponding macro is``_POSIX_MAX_CANON``. + +*_PC_MAX_INPUT* + returns the maximum length of an input line, where ``filedes`` or``path`` must refer to a terminal. The corresponding macro is``_POSIX_MAX_INPUT``. + +*_PC_NAME_MAX* + returns the maximum length of a filename in the directory ``path`` or``filedes``. The process is allowed to create. The corresponding macro + is ``_POSIX_NAME_MAX``. + +*_PC_PATH_MAX* + returns the maximum length of a relative pathname when ``path`` or``filedes`` is the current working directory. The corresponding macro + is ``_POSIX_PATH_MAX``. + +*_PC_PIPE_BUF* + returns the size of the pipe buffer, where ``filedes`` must refer to a + pipe or FIFO and ``path`` must refer to a FIFO. The corresponding macro + is ``_POSIX_PIPE_BUF``. + +*_PC_CHOWN_RESTRICTED* + returns nonzero if the ``chown()`` call may not be used on this file. If``filedes`` or ``path`` refer to a directory, then this applies to all + files in that directory. The corresponding macro is``_POSIX_CHOWN_RESTRICTED``. + +**NOTES:** + +NONE + +mknod - create a directory +-------------------------- +.. index:: mknod +.. index:: create a directory + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + #include <fcntl.h> + #include <sys/types.h> + #include <sys/stat.h> + long mknod( + const char \*pathname, + mode_t mode, + dev_t dev + ); + +**STATUS CODES:** + +``mknod`` returns zero on success, or -1 if an error occurred (in which case, +errno is set appropriately). + +*ENAMETOOLONG* + ``pathname`` was too long. + +*ENOENT* + A directory component in ``pathname`` does not exist or is a dangling symbolic + link. + +*ENOTDIR* + A component used in the directory ``pathname`` is not, in fact, a directory. + +*ENOMEM* + Insufficient kernel memory was available + +*EROFS* + ``pathname`` refers to a file on a read-only filesystem. + +*ELOOP* + ``pathname`` contains a reference to a circular symbolic link, ie a symbolic + link whose expansion contains a reference to itself. + +*ENOSPC* + The device containing ``pathname`` has no room for the new node. + +**DESCRIPTION:** + +``mknod`` attempts to create a filesystem node (file, device special file or +named pipe) named ``pathname``, specified by ``mode`` and ``dev``. + +``mode`` specifies both the permissions to use and the type of node to be created. + +It should be a combination (using bitwise OR) of one of the file types listed +below and the permissions for the new node. + +The permissions are modified by the process’s ``umask`` in the usual way: the +permissions of the created node are ``(mode & ~umask)``. + +The file type should be one of ``S_IFREG``, ``S_IFCHR``, ``S_IFBLK`` and``S_IFIFO`` to specify a normal file (which will be created empty), character +special file, block special file or FIFO (named pipe), respectively, or zero, which +will create a normal file. + +If the file type is ``S_IFCHR`` or ``S_IFBLK`` then ``dev`` specifies the major +and minor numbers of the newly created device special file; otherwise it is ignored. + +The newly created node will be owned by the effective uid of the process. If the +directory containing the node has the set group id bit set, or if the filesystem +is mounted with BSD group semantics, the new node will inherit the group ownership +from its parent directory; otherwise it will be owned by the effective gid of the +process. + +**NOTES:** + +NONE + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/index.rst b/posix_users/index.rst index b59b643..d375aaf 100644 --- a/posix_users/index.rst +++ b/posix_users/index.rst @@ -1 +1,70 @@ -.. include:: posix_users.rst +============================ +RTEMS POSIX API User’s Guide +============================ + +COPYRIGHT © 1988 - 2015. + +On-Line Applications Research Corporation (OAR). + +The authors have used their best efforts in preparing +this material. These efforts include the development, research, +and testing of the theories and programs to determine their +effectiveness. No warranty of any kind, expressed or implied, +with regard to the software or the material contained in this +document is provided. No liability arising out of the +application or use of any product described in this document is +assumed. The authors reserve the right to revise this material +and to make changes from time to time in the content hereof +without obligation to notify anyone of such revision or changes. + +The RTEMS Project is hosted at http://www.rtems.org. Any +inquiries concerning RTEMS, its related support components, or its +documentation should be directed to the Community Project hosted athttp://www.rtems.org. + +Any inquiries for commercial services including training, support, custom +development, application development assistance should be directed tohttp://www.rtems.com. + +.. COMMENT: This prevents a black box from being printed on "overflow" lines. + +.. COMMENT: The alternative is to rework a sentence to avoid this problem. + + +Table of Contents +----------------- + +.. toctree:: + + preface + + +.. toctree:: + :maxdepth: 3 + :numbered: + + process_creation_and_execution + signal + process_environment + files_and_directory + input_and_output + device_and_class_specific + language_specific_services + system_database + semaphore + mutex + condition_variable + memory_managment + scheduler + clock + timer + message_passing + thread + key + thread_cancellation + services_provided_by_c + services_provided_by_math + status_of_implementation + command + + +* :ref:`genindex` +* :ref:`search` diff --git a/posix_users/input_and_output.rst b/posix_users/input_and_output.rst new file mode 100644 index 0000000..8acb053 --- /dev/null +++ b/posix_users/input_and_output.rst @@ -0,0 +1,972 @@ +Input and Output Primitives Manager +################################### + +Introduction +============ + +The input and output primitives manager is ... + +The directives provided by the input and output primitives manager are: + +- ``pipe`` - Create an Inter-Process Channel + +- ``dup`` - Duplicates an open file descriptor + +- ``dup2`` - Duplicates an open file descriptor + +- ``close`` - Closes a file + +- ``read`` - Reads from a file + +- ``write`` - Writes to a file + +- ``fcntl`` - Manipulates an open file descriptor + +- ``lseek`` - Reposition read/write file offset + +- ``fsync`` - Synchronize file complete in-core state with that on disk + +- ``fdatasync`` - Synchronize file in-core data with that on disk + +- ``sync`` - Schedule file system updates + +- ``mount`` - Mount a file system + +- ``unmount`` - Unmount file systems + +- ``readv`` - Vectored read from a file + +- ``writev`` - Vectored write to a file + +- ``aio_read`` - Asynchronous Read + +- ``aio_write`` - Asynchronous Write + +- ``lio_listio`` - List Directed I/O + +- ``aio_error`` - Retrieve Error Status of Asynchronous I/O Operation + +- ``aio_return`` - Retrieve Return Status Asynchronous I/O Operation + +- ``aio_cancel`` - Cancel Asynchronous I/O Request + +- ``aio_suspend`` - Wait for Asynchronous I/O Request + +- ``aio_fsync`` - Asynchronous File Synchronization + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the input and output primitives manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +pipe - Create an Inter-Process Channel +-------------------------------------- +.. index:: pipe +.. index:: create an inter + +**CALLING SEQUENCE:** + +.. code:: c + + int pipe( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +dup - Duplicates an open file descriptor +---------------------------------------- +.. index:: dup +.. index:: duplicates an open file descriptor + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int dup( + int fildes + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor. + +*EINTR* + Function was interrupted by a signal. + +*EMFILE* + The process already has the maximum number of file descriptors open + and tried to open a new one. + +**DESCRIPTION:** + +The ``dup`` function returns the lowest numbered available file +descriptor. This new desciptor refers to the same open file as the +original descriptor and shares any locks. + +**NOTES:** + +NONE + +dup2 - Duplicates an open file descriptor +----------------------------------------- +.. index:: dup2 +.. index:: duplicates an open file descriptor + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int dup2( + int fildes, + int fildes2 + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor. + +*EINTR* + Function was interrupted by a signal. + +*EMFILE* + The process already has the maximum number of file descriptors open + and tried to open a new one. + +**DESCRIPTION:** + +``dup2`` creates a copy of the file descriptor ``oldfd``. + +The old and new descriptors may be used interchangeably. They share locks, file +position pointers and flags; for example, if the file position is modified by using``lseek`` on one of the descriptors, the position is also changed for the other. + +**NOTES:** + +NONE + +close - Closes a file +--------------------- +.. index:: close +.. index:: closes a file. + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int close( + int fildes + ); + +**STATUS CODES:** + +*EBADF* + Invalid file descriptor + +*EINTR* + Function was interrupted by a signal. + +**DESCRIPTION:** + +The ``close()`` function deallocates the file descriptor named by``fildes`` and makes it available for reuse. All outstanding +record locks owned by this process for the file are unlocked. + +**NOTES:** + +A signal can interrupt the ``close()`` function. In that case,``close()`` returns -1 with ``errno`` set to EINTR. The file +may or may not be closed. + +read - Reads from a file +------------------------ +.. index:: read +.. index:: reads from a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int read( + int fildes, + void \*buf, + unsigned int nbyte + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets ``errno`` to one of +the following: + +*EAGAIN* + The O_NONBLOCK flag is set for a file descriptor and the process + would be delayed in the I/O operation. + +*EBADF* + Invalid file descriptor + +*EINTR* + Function was interrupted by a signal. + +*EIO* + Input or output error + +*EINVAL* + Bad buffer pointer + +**DESCRIPTION:** + +The ``read()`` function reads ``nbyte`` bytes from the file +associated with ``fildes`` into the buffer pointed to by ``buf``. + +The ``read()`` function returns the number of bytes actually read +and placed in the buffer. This will be less than ``nbyte`` if: + +- The number of bytes left in the file is less than ``nbyte``. + +- The ``read()`` request was interrupted by a signal. + +- The file is a pipe or FIFO or special file with less than ``nbytes`` + immediately available for reading. + +When attempting to read from any empty pipe or FIFO: + +- If no process has the pipe open for writing, zero is returned to + indicate end-of-file. + +- If some process has the pipe open for writing and O_NONBLOCK is set, + -1 is returned and ``errno`` is set to EAGAIN. + +- If some process has the pipe open for writing and O_NONBLOCK is clear,``read()`` waits for some data to be written or the pipe to be closed. + +When attempting to read from a file other than a pipe or FIFO and no data +is available. + +- If O_NONBLOCK is set, -1 is returned and ``errno`` is set to EAGAIN. + +- If O_NONBLOCK is clear, ``read()`` waits for some data to become + available. + +- The O_NONBLOCK flag is ignored if data is available. + +**NOTES:** + +NONE + +write - Writes to a file +------------------------ +.. index:: write +.. index:: writes to a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + int write( + int fildes, + const void \*buf, + unsigned int nbytes + ); + +**STATUS CODES:** + +*EAGAIN* + The O_NONBLOCK flag is set for a file descriptor and the process + would be delayed in the I/O operation. + +*EBADF* + Invalid file descriptor + +*EFBIG* + An attempt was made to write to a file that exceeds the maximum file + size + +*EINTR* + The function was interrupted by a signal. + +*EIO* + Input or output error. + +*ENOSPC* + No space left on disk. + +*EPIPE* + Attempt to write to a pope or FIFO with no reader. + +*EINVAL* + Bad buffer pointer + +**DESCRIPTION:** + +The ``write()`` function writes ``nbyte`` from the array pointed +to by ``buf`` into the file associated with ``fildes``. + +If ``nybte`` is zero and the file is a regular file, the ``write()`` +function returns zero and has no other effect. If ``nbyte`` is zero +and the file is a special file, te results are not portable. + +The ``write()`` function returns the number of bytes written. This +number will be less than ``nbytes`` if there is an error. It will never +be greater than ``nbytes``. + +**NOTES:** + +NONE + +fcntl - Manipulates an open file descriptor +------------------------------------------- +.. index:: fcntl +.. index:: manipulates an open file descriptor + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <fcntl.h> + #include <unistd.h> + int fcntl( + int fildes, + int cmd + ); + +**STATUS CODES:** + +*EACCESS* + Search permission is denied for a direcotry in a file’s path + prefix. + +*EAGAIN* + The O_NONBLOCK flag is set for a file descriptor and the process + would be delayed in the I/O operation. + +*EBADF* + Invalid file descriptor + +*EDEADLK* + An ``fcntl`` with function F_SETLKW would cause a deadlock. + +*EINTR* + The functioin was interrupted by a signal. + +*EINVAL* + Invalid argument + +*EMFILE* + Too many file descriptor or in use by the process. + +*ENOLCK* + No locks available + +**DESCRIPTION:** + +``fcntl()`` performs one of various miscellaneous operations on``fd``. The operation in question is determined by ``cmd``: + +*F_DUPFD* + Makes ``arg`` be a copy of ``fd``, closing ``fd`` first if necessary. + The same functionality can be more easily achieved by using ``dup2()``. + The old and new descriptors may be used interchangeably. They share locks, + file position pointers and flags; for example, if the file position is + modified by using ``lseek()`` on one of the descriptors, the position is + also changed for the other. + The two descriptors do not share the close-on-exec flag, however. The + close-on-exec flag of the copy is off, meaning that it will be closed on + exec. + On success, the new descriptor is returned. + +*F_GETFD* + Read the close-on-exec flag. If the low-order bit is 0, the file will + remain open across exec, otherwise it will be closed. + +*F_SETFD* + Set the close-on-exec flag to the value specified by ``arg`` (only the least + significant bit is used). + +*F_GETFL* + Read the descriptor’s flags (all flags (as set by open()) are returned). + +*F_SETFL* + Set the descriptor’s flags to the value specified by ``arg``. Only``O_APPEND`` and ``O_NONBLOCK`` may be set. + The flags are shared between copies (made with ``dup()`` etc.) of the same + file descriptor. + The flags and their semantics are described in ``open()``. + +*F_GETLK, F_SETLK and F_SETLKW* + Manage discretionary file locks. The third argument ``arg`` is a pointer to a + struct flock (that may be overwritten by this call). + +*F_GETLK* + Return the flock structure that prevents us from obtaining the lock, or set the``l_type`` field of the lock to ``F_UNLCK`` if there is no obstruction. + +*F_SETLK* + The lock is set (when ``l_type`` is ``F_RDLCK`` or ``F_WRLCK``) or + cleared (when it is ``F_UNLCK``. If lock is held by someone else, this + call returns -1 and sets ``errno`` to EACCES or EAGAIN. + +*F_SETLKW* + Like ``F_SETLK``, but instead of returning an error we wait for the lock to + be released. + +*F_GETOWN* + Get the process ID (or process group) of the owner of a socket. + Process groups are returned as negative values. + +*F_SETOWN* + Set the process or process group that owns a socket. + For these commands, ownership means receiving ``SIGIO`` or ``SIGURG`` + signals. + Process groups are specified using negative values. + +**NOTES:** + +The errors returned by ``dup2`` are different from those returned by``F_DUPFD``. + +lseek - Reposition read/write file offset +----------------------------------------- +.. index:: lseek +.. index:: reposition read/write file offset + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <unistd.h> + int lseek( + int fildes, + off_t offset, + int whence + ); + +**STATUS CODES:** + +*EBADF* + ``fildes`` is not an open file descriptor. + +*ESPIPE* + ``fildes`` is associated with a pipe, socket or FIFO. + +*EINVAL* + ``whence`` is not a proper value. + +**DESCRIPTION:** + +The ``lseek`` function repositions the offset of the file descriptor``fildes`` to the argument offset according to the directive whence. +The argument ``fildes`` must be an open file descriptor. ``Lseek`` +repositions the file pointer fildes as follows: + +- If ``whence`` is SEEK_SET, the offset is set to ``offset`` bytes. + +- If ``whence`` is SEEK_CUR, the offset is set to its current location + plus offset bytes. + +- If ``whence`` is SEEK_END, the offset is set to the size of the + file plus ``offset`` bytes. + +The ``lseek`` function allows the file offset to be set beyond the end +of the existing end-of-file of the file. If data is later written at this +point, subsequent reads of the data in the gap return bytes of zeros +(until data is actually written into the gap). + +Some devices are incapable of seeking. The value of the pointer associated +with such a device is undefined. + +**NOTES:** + +NONE + +fsync - Synchronize file complete in-core state with that on disk +----------------------------------------------------------------- +.. index:: fsync +.. index:: synchronize file complete in + +**CALLING SEQUENCE:** + +.. code:: c + + int fsync( + int fd + ); + +**STATUS CODES:** + +On success, zero is returned. On error, -1 is returned, and ``errno`` +is set appropriately. + +*EBADF* + ``fd`` is not a valid descriptor open for writing + +*EINVAL* + ``fd`` is bound to a special file which does not support support synchronization + +*EROFS* + ``fd`` is bound to a special file which does not support support synchronization + +*EIO* + An error occurred during synchronization + +**DESCRIPTION:** + +``fsync`` copies all in-core parts of a file to disk. + +**NOTES:** + +NONE + +fdatasync - Synchronize file in-core data with that on disk +----------------------------------------------------------- +.. index:: fdatasync +.. index:: synchronize file in + +**CALLING SEQUENCE:** + +.. code:: c + + int fdatasync( + int fd + ); + +**STATUS CODES:** + +On success, zero is returned. On error, -1 is returned, and ``errno`` is +set appropriately. + +*EBADF* + ``fd`` is not a valid file descriptor open for writing. + +*EINVAL* + ``fd`` is bound to a special file which does not support synchronization. + +*EIO* + An error occurred during synchronization. + +*EROFS* + ``fd`` is bound to a special file which dows not support synchronization. + +**DESCRIPTION:** + +``fdatasync`` flushes all data buffers of a file to disk (before the system call +returns). It resembles ``fsync`` but is not required to update the metadata such +as access time. + +Applications that access databases or log files often write a tiny data fragment +(e.g., one line in a log file) and then call ``fsync`` immediately in order to +ensure that the written data is physically stored on the harddisk. Unfortunately, +fsync will always initiate two write operations: one for the newly written data and +another one in order to update the modification time stored in the inode. If the +modification time is not a part of the transaction concept ``fdatasync`` can be +used to avoid unnecessary inode disk write operations. + +**NOTES:** + +NONE + +sync - Schedule file system updates +----------------------------------- +.. index:: sync +.. index:: synchronize file systems + +**CALLING SEQUENCE:** + +.. code:: c + + void sync(void); + +**STATUS CODES:** + +NONE + +**DESCRIPTION:** + +The ``sync`` service causes all information in memory that updates +file systems to be scheduled for writing out to all file systems. + +**NOTES:** + +The writing of data to the file systems is only guaranteed to be +scheduled upon return. It is not necessarily complete upon return +from ``sync``. + +mount - Mount a file system +--------------------------- +.. index:: mount +.. index:: mount a file system + +**CALLING SEQUENCE:** + +.. code:: c + + #include <libio.h> + int mount( + rtems_filesystem_mount_table_entry_t \**mt_entry, + rtems_filesystem_operations_table \*fs_ops, + rtems_filesystem_options_t fsoptions, + char \*device, + char \*mount_point + ); + +**STATUS CODES:** + +*EXXX* + +**DESCRIPTION:** + +The ``mount`` routines mounts the filesystem class +which uses the filesystem operations specified by ``fs_ops`` +and ``fsoptions``. The filesystem is mounted at the directory``mount_point`` and the mode of the mounted filesystem is +specified by ``fsoptions``. If this filesystem class requires +a device, then the name of the device must be specified by ``device``. + +If this operation succeeds, the mount table entry for the mounted +filesystem is returned in ``mt_entry``. + +**NOTES:** + +NONE + +unmount - Unmount file systems +------------------------------ +.. index:: unmount +.. index:: unmount file systems + +**CALLING SEQUENCE:** + +.. code:: c + + #include <libio.h> + int unmount( + const char \*mount_path + ); + +**STATUS CODES:** + +*EXXX* + +**DESCRIPTION:** + +The ``unmount`` routine removes the attachment of the filesystem specified +by ``mount_path``. + +**NOTES:** + +NONE + +readv - Vectored read from a file +--------------------------------- +.. index:: readv +.. index:: vectored read from a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/uio.h> + ssize_t readv( + int fd, + const struct iovec \*iov, + int iovcnt + ); + +**STATUS CODES:** + +In addition to the errors detected by``Input and Output Primitives Manager read - Reads from a file, read()``, +this routine may return -1 and sets ``errno`` based upon the following +errors: + +*EINVAL* + The sum of the ``iov_len`` values in the iov array overflowed an``ssize_t``. + +*EINVAL* + The ``iovcnt`` argument was less than or equal to 0, or greater + than ``IOV_MAX``. + +**DESCRIPTION:** + +The ``readv()`` function is equivalent to ``read()`` +except as described here. The ``readv()`` function shall place +the input data into the ``iovcnt`` buffers specified by the +members of the ``iov`` array: ``iov[0], iov[1], ..., iov[iovcnt-1]``. + +Each ``iovec`` entry specifies the base address and length of an area +in memory where data should be placed. The ``readv()`` function +always fills an area completely before proceeding to the next. + +**NOTES:** + +NONE + +writev - Vectored write to a file +--------------------------------- +.. index:: writev +.. index:: vectored write to a file + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/uio.h> + ssize_t writev( + int fd, + const struct iovec \*iov, + int iovcnt + ); + +**STATUS CODES:** + +In addition to the errors detected by``Input and Output Primitives Manager write - Write to a file, write()``, +this routine may return -1 and sets ``errno`` based upon the following +errors: + +*EINVAL* + The sum of the ``iov_len`` values in the iov array overflowed an``ssize_t``. + +*EINVAL* + The ``iovcnt`` argument was less than or equal to 0, or greater + than ``IOV_MAX``. + +**DESCRIPTION:** + +The ``writev()`` function is equivalent to ``write()``, +except as noted here. The ``writev()`` function gathers output +data from the ``iovcnt`` buffers specified by the members of +the ``iov array``: ``iov[0], iov[1], ..., iov[iovcnt-1]``. +The ``iovcnt`` argument is valid if greater than 0 and less +than or equal to ``IOV_MAX``. + +Each ``iovec`` entry specifies the base address and length of +an area in memory from which data should be written. The ``writev()`` +function always writes a complete area before proceeding to the next. + +If ``fd`` refers to a regular file and all of the ``iov_len`` +members in the array pointed to by ``iov`` are 0, ``writev()`` +returns 0 and has no other effect. For other file types, the behavior +is unspecified by POSIX. + +**NOTES:** + +NONE + +aio_read - Asynchronous Read +---------------------------- +.. index:: aio_read +.. index:: asynchronous read + +**CALLING SEQUENCE:** + +.. code:: c + + int aio_read( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +aio_write - Asynchronous Write +------------------------------ +.. index:: aio_write +.. index:: asynchronous write + +**CALLING SEQUENCE:** + +.. code:: c + + int aio_write( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +lio_listio - List Directed I/O +------------------------------ +.. index:: lio_listio +.. index:: list directed i/o + +**CALLING SEQUENCE:** + +.. code:: c + + int lio_listio( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +aio_error - Retrieve Error Status of Asynchronous I/O Operation +--------------------------------------------------------------- +.. index:: aio_error +.. index:: retrieve error status of asynchronous i/o operation + +**CALLING SEQUENCE:** + +.. code:: c + + int aio_error( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +aio_return - Retrieve Return Status Asynchronous I/O Operation +-------------------------------------------------------------- +.. index:: aio_return +.. index:: retrieve return status asynchronous i/o operation + +**CALLING SEQUENCE:** + +.. code:: c + + int aio_return( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +aio_cancel - Cancel Asynchronous I/O Request +-------------------------------------------- +.. index:: aio_cancel +.. index:: cancel asynchronous i/o request + +**CALLING SEQUENCE:** + +.. code:: c + + int aio_cancel( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +aio_suspend - Wait for Asynchronous I/O Request +----------------------------------------------- +.. index:: aio_suspend +.. index:: wait for asynchronous i/o request + +**CALLING SEQUENCE:** + +.. code:: c + + int aio_suspend( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +aio_fsync - Asynchronous File Synchronization +--------------------------------------------- +.. index:: aio_fsync +.. index:: asynchronous file synchronization + +**CALLING SEQUENCE:** + +.. code:: c + + int aio_fsync( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +This routine is not currently supported by RTEMS but could be +in a future version. + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/key.rst b/posix_users/key.rst new file mode 100644 index 0000000..1ce6c2a --- /dev/null +++ b/posix_users/key.rst @@ -0,0 +1,195 @@ +Key Manager +########### + +Introduction +============ + +The key manager allows for the creation and deletion of Data keys +specific to threads. + +The directives provided by the key manager are: + +- ``pthread_key_create`` - Create Thread Specific Data Key + +- ``pthread_key_delete`` - Delete Thread Specific Data Key + +- ``pthread_setspecific`` - Set Thread Specific Key Value + +- ``pthread_getspecific`` - Get Thread Specific Key Value + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the key manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +pthread_key_create - Create Thread Specific Data Key +---------------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_key_create( + pthread_key_t \*key, + void (\*destructor)( void ) + ); + +**STATUS CODES:** + +*EAGAIN* + There were not enough resources available to create another key. + +*ENOMEM* + Insufficient memory exists to create the key. + +**DESCRIPTION** + +The pthread_key_create() function shall create a thread-specific data +key visible to all threads in the process. Key values provided by +pthread_key_create() are opaque objects used to locate thread-specific +data. Although the same key value may be used by different threads, the +values bound to the key by pthread_setspecific() are maintained on a +per-thread basis and persist for the life of the calling thread. + +Upon key creation, the value NULL shall be associated with the new key +in all active threads. Upon thread creation, the value NULL shall be +associated with all defined keys in the new thread. + +**NOTES** + +An optional destructor function may be associated with each key value. +At thread exit, if a key value has a non-NULL destructor pointer, and +the thread has a non-NULL value associated with that key, the value of +the key is set to NULL, and then the function pointed to is called with +the previously associated value as its sole argument. The order of +destructor calls is unspecified if more than one destructor exists for +a thread when it exits. + +pthread_key_delete - Delete Thread Specific Data Key +---------------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_key_delete( + pthread_key_t key); + +**STATUS CODES:** + +*EINVAL* + The key was invalid + +**DESCRIPTION:** + +The pthread_key_delete() function shall delete a thread-specific data key +previously returned by pthread_key_create(). The thread-specific data +values associated with key need not be NULL at the time pthread_key_delete() +is called. It is the responsibility of the application to free any +application storage or perform any cleanup actions for data structures related +to the deleted key or associated thread-specific data in any +threads; this cleanup can be done either before or after +pthread_key_delete() is called. Any attempt to use key following the call to +pthread_key_delete() results in undefined behavior. + +**NOTES:** + +The pthread_key_delete() function shall be callable from within +destructor functions. No destructor functions shall be invoked by +pthread_key_delete(). Any destructor function that may have been +associated with key shall no longer be called upon thread exit. + +pthread_setspecific - Set Thread Specific Key Value +--------------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_setspecific( + pthread_key_t key, + const void \*value + ); + +**STATUS CODES:** + +*EINVAL* + The specified key is invalid. + +**DESCRIPTION:** + +The pthread_setspecific() function shall associate a thread-specific value +with a key obtained via a previous call to pthread_key_create(). +Different threads may bind different values to the same key. These values +are typically pointers to blocks of dynamically allocated memory that +have been reserved for use by the calling thread. + +**NOTES:** + +The effect of calling pthread_setspecific() with a key value not obtained +from pthread_key_create() or after key has +been deleted with pthread_key_delete() is undefined. + +pthread_setspecific() may be called from a thread-specific data +destructor function. Calling pthread_setspecific() from a thread-specific +data destructor routine may result either in lost storage (after at least +PTHREAD_DESTRUCTOR_ITERATIONS attempts at destruction) or in an infinite loop. + +pthread_getspecific - Get Thread Specific Key Value +--------------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + void \*pthread_getspecific( + pthread_key_t key + ); + +**STATUS CODES:** + +*NULL* + There is no thread-specific data associated with the specified key. + +*non-NULL* + The data associated with the specified key. + +**DESCRIPTION:** + +The pthread_getspecific() function shall return the value currently bound to +the specified key on behalf of the calling thread. + +**NOTES:** + +The effect of calling pthread_getspecific() with a key value not obtained from +pthread_key_create() or after key has +been deleted with pthread_key_delete() is undefined. + +pthread_getspecific() may be called from a thread-specific data destructor +function. A call to pthread_getspecific() for the thread-specific data key +being destroyed shall return the value NULL, unless the value is changed +(after the destructor starts) by a call to pthread_setspecific(). + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/language_specific_services.rst b/posix_users/language_specific_services.rst new file mode 100644 index 0000000..be8c276 --- /dev/null +++ b/posix_users/language_specific_services.rst @@ -0,0 +1,518 @@ +Language-Specific Services for the C Programming Language Manager +################################################################# + +Introduction +============ + +The +language-specific services for the C programming language manager is ... + +The directives provided by the language-specific services for the C programming language manager are: + +- ``setlocale`` - Set the Current Locale + +- ``fileno`` - Obtain File Descriptor Number for this File + +- ``fdopen`` - Associate Stream with File Descriptor + +- ``flockfile`` - Acquire Ownership of File Stream + +- ``ftrylockfile`` - Poll to Acquire Ownership of File Stream + +- ``funlockfile`` - Release Ownership of File Stream + +- ``getc_unlocked`` - Get Character without Locking + +- ``getchar_unlocked`` - Get Character from stdin without Locking + +- ``putc_unlocked`` - Put Character without Locking + +- ``putchar_unlocked`` - Put Character to stdin without Locking + +- ``setjmp`` - Save Context for Non-Local Goto + +- ``longjmp`` - Non-Local Jump to a Saved Context + +- ``sigsetjmp`` - Save Context with Signal Status for Non-Local Goto + +- ``siglongjmp`` - Non-Local Jump with Signal Status to a Saved Context + +- ``tzset`` - Initialize Time Conversion Information + +- ``strtok_r`` - Reentrant Extract Token from String + +- ``asctime_r`` - Reentrant struct tm to ASCII Time Conversion + +- ``ctime_r`` - Reentrant time_t to ASCII Time Conversion + +- ``gmtime_r`` - Reentrant UTC Time Conversion + +- ``localtime_r`` - Reentrant Local Time Conversion + +- ``rand_r`` - Reentrant Random Number Generation + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the language-specific services for the C programming language manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +setlocale - Set the Current Locale +---------------------------------- +.. index:: setlocale +.. index:: set the current locale + +**CALLING SEQUENCE:** + +.. code:: c + + int setlocale( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +fileno - Obtain File Descriptor Number for this File +---------------------------------------------------- +.. index:: fileno +.. index:: obtain file descriptor number for this file + +**CALLING SEQUENCE:** + +.. code:: c + + int fileno( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +fdopen - Associate Stream with File Descriptor +---------------------------------------------- +.. index:: fdopen +.. index:: associate stream with file descriptor + +**CALLING SEQUENCE:** + +.. code:: c + + int fdopen( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +flockfile - Acquire Ownership of File Stream +-------------------------------------------- +.. index:: flockfile +.. index:: acquire ownership of file stream + +**CALLING SEQUENCE:** + +.. code:: c + + int flockfile( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +ftrylockfile - Poll to Acquire Ownership of File Stream +------------------------------------------------------- +.. index:: ftrylockfile +.. index:: poll to acquire ownership of file stream + +**CALLING SEQUENCE:** + +.. code:: c + + int ftrylockfile( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +funlockfile - Release Ownership of File Stream +---------------------------------------------- +.. index:: funlockfile +.. index:: release ownership of file stream + +**CALLING SEQUENCE:** + +.. code:: c + + int funlockfile( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getc_unlocked - Get Character without Locking +--------------------------------------------- +.. index:: getc_unlocked +.. index:: get character without locking + +**CALLING SEQUENCE:** + +.. code:: c + + int getc_unlocked( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getchar_unlocked - Get Character from stdin without Locking +----------------------------------------------------------- +.. index:: getchar_unlocked +.. index:: get character from stdin without locking + +**CALLING SEQUENCE:** + +.. code:: c + + int getchar_unlocked( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +putc_unlocked - Put Character without Locking +--------------------------------------------- +.. index:: putc_unlocked +.. index:: put character without locking + +**CALLING SEQUENCE:** + +.. code:: c + + int putc_unlocked( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +putchar_unlocked - Put Character to stdin without Locking +--------------------------------------------------------- +.. index:: putchar_unlocked +.. index:: put character to stdin without locking + +**CALLING SEQUENCE:** + +.. code:: c + + int putchar_unlocked( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +setjmp - Save Context for Non-Local Goto +---------------------------------------- +.. index:: setjmp +.. index:: save context for non + +**CALLING SEQUENCE:** + +.. code:: c + + int setjmp( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +longjmp - Non-Local Jump to a Saved Context +------------------------------------------- +.. index:: longjmp +.. index:: non + +**CALLING SEQUENCE:** + +.. code:: c + + int longjmp( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +sigsetjmp - Save Context with Signal Status for Non-Local Goto +-------------------------------------------------------------- +.. index:: sigsetjmp +.. index:: save context with signal status for non + +**CALLING SEQUENCE:** + +.. code:: c + + int sigsetjmp( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +siglongjmp - Non-Local Jump with Signal Status to a Saved Context +----------------------------------------------------------------- +.. index:: siglongjmp +.. index:: non + +**CALLING SEQUENCE:** + +.. code:: c + + int siglongjmp( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +tzset - Initialize Time Conversion Information +---------------------------------------------- +.. index:: tzset +.. index:: initialize time conversion information + +**CALLING SEQUENCE:** + +.. code:: c + + int tzset( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +strtok_r - Reentrant Extract Token from String +---------------------------------------------- +.. index:: strtok_r +.. index:: reentrant extract token from string + +**CALLING SEQUENCE:** + +.. code:: c + + int strtok_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +asctime_r - Reentrant struct tm to ASCII Time Conversion +-------------------------------------------------------- +.. index:: asctime_r +.. index:: reentrant struct tm to ascii time conversion + +**CALLING SEQUENCE:** + +.. code:: c + + int asctime_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +ctime_r - Reentrant time_t to ASCII Time Conversion +--------------------------------------------------- +.. index:: ctime_r +.. index:: reentrant time_t to ascii time conversion + +**CALLING SEQUENCE:** + +.. code:: c + + int ctime_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +gmtime_r - Reentrant UTC Time Conversion +---------------------------------------- +.. index:: gmtime_r +.. index:: reentrant utc time conversion + +**CALLING SEQUENCE:** + +.. code:: c + + int gmtime_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +localtime_r - Reentrant Local Time Conversion +--------------------------------------------- +.. index:: localtime_r +.. index:: reentrant local time conversion + +**CALLING SEQUENCE:** + +.. code:: c + + int localtime_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +rand_r - Reentrant Random Number Generation +------------------------------------------- +.. index:: rand_r +.. index:: reentrant random number generation + +**CALLING SEQUENCE:** + +.. code:: c + + int rand_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/memory_managment.rst b/posix_users/memory_managment.rst new file mode 100644 index 0000000..05bb99d --- /dev/null +++ b/posix_users/memory_managment.rst @@ -0,0 +1,265 @@ +Memory Management Manager +######################### + +Introduction +============ + +The +memory management manager is ... + +The directives provided by the memory management manager are: + +- ``mlockall`` - Lock the Address Space of a Process + +- ``munlockall`` - Unlock the Address Space of a Process + +- ``mlock`` - Lock a Range of the Process Address Space + +- ``munlock`` - Unlock a Range of the Process Address Space + +- ``mmap`` - Map Process Addresses to a Memory Object + +- ``munmap`` - Unmap Previously Mapped Addresses + +- ``mprotect`` - Change Memory Protection + +- ``msync`` - Memory Object Synchronization + +- ``shm_open`` - Open a Shared Memory Object + +- ``shm_unlink`` - Remove a Shared Memory Object + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the memory management manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +mlockall - Lock the Address Space of a Process +---------------------------------------------- +.. index:: mlockall +.. index:: lock the address space of a process + +**CALLING SEQUENCE:** + +.. code:: c + + int mlockall( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +munlockall - Unlock the Address Space of a Process +-------------------------------------------------- +.. index:: munlockall +.. index:: unlock the address space of a process + +**CALLING SEQUENCE:** + +.. code:: c + + int munlockall( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +mlock - Lock a Range of the Process Address Space +------------------------------------------------- +.. index:: mlock +.. index:: lock a range of the process address space + +**CALLING SEQUENCE:** + +.. code:: c + + int mlock( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +munlock - Unlock a Range of the Process Address Space +----------------------------------------------------- +.. index:: munlock +.. index:: unlock a range of the process address space + +**CALLING SEQUENCE:** + +.. code:: c + + int munlock( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +mmap - Map Process Addresses to a Memory Object +----------------------------------------------- +.. index:: mmap +.. index:: map process addresses to a memory object + +**CALLING SEQUENCE:** + +.. code:: c + + int mmap( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +munmap - Unmap Previously Mapped Addresses +------------------------------------------ +.. index:: munmap +.. index:: unmap previously mapped addresses + +**CALLING SEQUENCE:** + +.. code:: c + + int munmap( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +mprotect - Change Memory Protection +----------------------------------- +.. index:: mprotect +.. index:: change memory protection + +**CALLING SEQUENCE:** + +.. code:: c + + int mprotect( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +msync - Memory Object Synchronization +------------------------------------- +.. index:: msync +.. index:: memory object synchronization + +**CALLING SEQUENCE:** + +.. code:: c + + int msync( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +shm_open - Open a Shared Memory Object +-------------------------------------- +.. index:: shm_open +.. index:: open a shared memory object + +**CALLING SEQUENCE:** + +.. code:: c + + int shm_open( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +shm_unlink - Remove a Shared Memory Object +------------------------------------------ +.. index:: shm_unlink +.. index:: remove a shared memory object + +**CALLING SEQUENCE:** + +.. code:: c + + int shm_unlink( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/message_passing.rst b/posix_users/message_passing.rst new file mode 100644 index 0000000..6192587 --- /dev/null +++ b/posix_users/message_passing.rst @@ -0,0 +1,665 @@ +Message Passing Manager +####################### + +Introduction +============ + +The message passing manager is the means to provide communication and +synchronization capabilities using POSIX message queues. + +The directives provided by the message passing manager are: + +- ``mq_open`` - Open a Message Queue + +- ``mq_close`` - Close a Message Queue + +- ``mq_unlink`` - Remove a Message Queue + +- ``mq_send`` - Send a Message to a Message Queue + +- ``mq_receive`` - Receive a Message from a Message Queue + +- ``mq_notify`` - Notify Process that a Message is Available + +- ``mq_setattr`` - Set Message Queue Attributes + +- ``mq_getattr`` - Get Message Queue Attributes + +Background +========== + +Theory +------ + +Message queues are named objects that operate with readers and writers. +In addition, a message queue is a priority queue of discrete messages. +POSIX message queues offer a certain, basic amount of application access +to, and control over, the message queue geometry that can be changed. + +Messages +-------- + +A message is a variable length buffer where information can be stored to +support communication. The length of the message and the information +stored in that message are user-defined and can be actual data, +pointer(s), or empty. There is a maximum acceptable length for a message +that is associated with each message queue. + +Message Queues +-------------- + +Message queues are named objects similar to the pipes of POSIX. They are +a means of communicating data between multiple processes and for passing +messages among tasks and ISRs. Message queues can contain a variable +number of messages from 0 to an upper limit that is user defined. The +maximum length of the message can be set on a per message queue basis. +Normally messages are sent and received from the message queue in FIFO +order. However, messages can also be prioritized and a priority queue +established for the passing of messages. Synchronization is needed when a +task waits for a message to arrive at a queue. Also, a task may poll a +queue for the arrival of a message... index:: mqd_t + +The message queue descriptor ``mqd_t`` represents the message queue. It is +passed as an argument to all of the message queue functions. + +Building a Message Queue Attribute Set +-------------------------------------- + +The mq_attr structure is used to define the characteristics of the message +queue... index:: mq_attr + +.. code:: c + + typedef struct mq_attr{ + long mq_flags; + long mq_maxmsg; + long mq_msgsize; + long mq_curmsgs; + }; + +All of these attributes are set when the message queue is created using +mq_open. The mq_flags field is not used in the creation of a message +queue, it is only used by mq_setattr and mq_getattr. The structure +mq_attr is passed as an argument to mq_setattr and mq_getattr. + +The mq_flags contain information affecting the behavior of the message +queue. The O_NONBLOCK mq_flag is the only flag that is defined. In +mq_setattr, the mq_flag can be set to dynamically change the blocking and +non-blocking behavior of the message queue. If the non-block flag is set +then the message queue is non-blocking, and requests to send and receive +messages do not block waiting for resources. For a blocking message +queue, a request to send might have to wait for an empty message queue, +and a request to receive might have to wait for a message to arrive on the +queue. Both mq_maxmsg and mq_msgsize affect the sizing of the message +queue. mq_maxmsg specifies how many messages the queue can hold at any +one time. mq_msgsize specifies the size of any one message on the queue. +If either of these limits is exceeded, an error message results. + +Upon return from mq_getattr, the mq_curmsgs is set according to the +current state of the message queue. This specifies the number of messages +currently on the queue. + +Notification of a Message on the Queue +-------------------------------------- + +Every message queue has the ability to notify one (and only one) process +whenever the queue’s state changes from empty (0 messages) to nonempty. +This means that the process does not have to block or constantly poll +while it waits for a message. By calling mq_notify, you can attach a +notification request to a message queue. When a message is received by an +empty queue, if there are no processes blocked and waiting for the +message, then the queue notifies the requesting process of a message +arrival. There is only one signal sent by the message queue, after that +the notification request is de-registered and another process can attach +its notification request. After receipt of a notification, a process must +re-register if it wishes to be notified again. + +If there is a process blocked and waiting for the message, that process +gets the message, and notification is not sent. It is also possible for +another process to receive the message after the notification is sent but +before the notified process has sent its receive request. + +Only one process can have a notification request attached to a message +queue at any one time. If another process attempts to register a +notification request, it fails. You can de-register for a message queue +by passing a NULL to mq_notify, this removes any notification request +attached to the queue. Whenever the message queue is closed, all +notification attachments are removed. + +POSIX Interpretation Issues +--------------------------- + +There is one significant point of interpretation related to +the RTEMS implementation of POSIX message queues: + +*What happens to threads already blocked on a message queue when the +mode of that same message queue is changed from blocking to non-blocking?* + +The RTEMS POSIX implementation decided to unblock all waiting tasks +with an ``EAGAIN`` status just as if a non-blocking version of +the same operation had returned unsatisfied. This case is not +discussed in the POSIX standard and other implementations may have +chosen alternative behaviors. + +Operations +========== + +Opening or Creating a Message Queue +----------------------------------- + +If the message queue already exists, mq_open() opens it, if the message +queue does not exist, mq_open() creates it. When a message queue is +created, the geometry of the message queue is contained in the attribute +structure that is passed in as an argument. This includes mq_msgsize that +dictates the maximum size of a single message, and the mq_maxmsg that +dictates the maximum number of messages the queue can hold at one time. +The blocking or non-blocking behavior of the queue can also specified. + +Closing a Message Queue +----------------------- + +The mq_close() function is used to close the connection made to a message +queue that was made during mq_open. The message queue itself and the +messages on the queue are persistent and remain after the queue is closed. + +Removing a Message Queue +------------------------ + +The mq_unlink() function removes the named message queue. If the message +queue is not open when mq_unlink is called, then the queue is immediately +eliminated. Any messages that were on the queue are lost, and the queue +can not be opened again. If processes have the queue open when mq_unlink +is called, the removal of the queue is delayed until the last process +using the queue has finished. However, the name of the message queue is +removed so that no other process can open it. + +Sending a Message to a Message Queue +------------------------------------ + +The mq_send() function adds the message in priority order to the message +queue. Each message has an assigned a priority. The highest priority +message is be at the front of the queue. + +The maximum number of messages that a message queue may accept is +specified at creation by the mq_maxmsg field of the attribute structure. +If this amount is exceeded, the behavior of the process is determined +according to what oflag was used when the message queue was opened. If +the queue was opened with O_NONBLOCK flag set, the process does not block, +and an error is returned. If the O_NONBLOCK flag was not set, the process +does block and wait for space on the queue. + +Receiving a Message from a Message Queue +---------------------------------------- + +The mq_receive() function is used to receive the oldest of the highest +priority message(s) from the message queue specified by mqdes. The +messages are received in FIFO order within the priorities. The received +message’s priority is stored in the location referenced by the msg_prio. +If the msg_prio is a NULL, the priority is discarded. The message is +removed and stored in an area pointed to by msg_ptr whose length is of +msg_len. The msg_len must be at least equal to the mq_msgsize attribute +of the message queue. + +The blocking behavior of the message queue is set by O_NONBLOCK at mq_open +or by setting O_NONBLOCK in mq_flags in a call to mq_setattr. If this is +a blocking queue, the process does block and wait on an empty queue. If +this a non-blocking queue, the process does not block. Upon successful +completion, mq_receive returns the length of the selected message in bytes +and the message is removed from the queue. + +Notification of Receipt of a Message on an Empty Queue +------------------------------------------------------ + +The mq_notify() function registers the calling process to be notified of +message arrival at an empty message queue. Every message queue has the +ability to notify one (and only one) process whenever the queue’s state +changes from empty (0 messages) to nonempty. This means that the process +does not have to block or constantly poll while it waits for a message. +By calling mq_notify, a notification request is attached to a message +queue. When a message is received by an empty queue, if there are no +processes blocked and waiting for the message, then the queue notifies the +requesting process of a message arrival. There is only one signal sent by +the message queue, after that the notification request is de-registered +and another process can attach its notification request. After receipt of +a notification, a process must re-register if it wishes to be notified +again. + +If there is a process blocked and waiting for the message, that process +gets the message, and notification is not sent. Only one process can have +a notification request attached to a message queue at any one time. If +another process attempts to register a notification request, it fails. +You can de-register for a message queue by passing a NULL to mq_notify, +this removes any notification request attached to the queue. Whenever the +message queue is closed, all notification attachments are removed. + +Setting the Attributes of a Message Queue +----------------------------------------- + +The mq_setattr() function is used to set attributes associated with the +open message queue description referenced by the message queue descriptor +specified by mqdes. The \*omqstat represents the old or previous +attributes. If omqstat is non-NULL, the function mq_setattr() stores, in +the location referenced by omqstat, the previous message queue attributes +and the current queue status. These values are the same as would be +returned by a call to mq_getattr() at that point. + +There is only one mq_attr.mq_flag that can be altered by this call. This +is the flag that deals with the blocking and non-blocking behavior of the +message queue. If the flag is set then the message queue is non-blocking, +and requests to send or receive do not block while waiting for resources. +If the flag is not set, then message send and receive may involve waiting +for an empty queue or waiting for a message to arrive. + +Getting the Attributes of a Message Queue +----------------------------------------- + +The mq_getattr() function is used to get status information and attributes +of the message queue associated with the message queue descriptor. The +results are returned in the mq_attr structure referenced by the mqstat +argument. All of these attributes are set at create time, except the +blocking/non-blocking behavior of the message queue which can be +dynamically set by using mq_setattr. The attribute mq_curmsg is set to +reflect the number of messages on the queue at the time that mq_getattr +was called. + +Directives +========== + +This section details the message passing manager’s directives. A +subsection is dedicated to each of this manager’s directives and describes +the calling sequence, related constants, usage, and status codes. + +mq_open - Open a Message Queue +------------------------------ +.. index:: mq_open +.. index:: open a message queue + +**CALLING SEQUENCE:** + +.. code:: c + + #include <mqueue.h> + mqd_t mq_open( + const char \*name, + int oflag, + mode_t mode, + struct mq_attr \*attr + ); + +**STATUS CODES:** + +``EACCES`` - Either the message queue exists and the permissions +requested in oflags were denied, or the message does not exist and +permission to create one is denied. + +``EEXIST`` - You tried to create a message queue that already exists. + +``EINVAL`` - An inappropriate name was given for the message queue, or +the values of mq-maxmsg or mq_msgsize were less than 0. + +``ENOENT`` - The message queue does not exist, and you did not specify +to create it. + +``EINTR`` - The call to mq_open was interrupted by a signal. + +``EMFILE`` - The process has too many files or message queues open. +This is a process limit error. + +``ENFILE`` - The system has run out of resources to support more open +message queues. This is a system error. + +``ENAMETOOLONG`` - mq_name is too long. + +**DESCRIPTION:** + +The mq_open () function establishes the connection between a process and a +message queue with a message queue descriptor. If the message queue +already exists, mq_open opens it, if the message queue does not exist, +mq_open creates it. Message queues can have multiple senders and +receivers. If mq_open is successful, the function returns a message queue +descriptor. Otherwise, the function returns a -1 and sets ’errno’ to +indicate the error. + +The name of the message queue is used as an argument. For the best of +portability, the name of the message queue should begin with a "/" and no +other "/" should be in the name. Different systems interpret the name in +different ways. + +The oflags contain information on how the message is opened if the queue +already exists. This may be O_RDONLY for read only, O_WRONLY for write +only, of O_RDWR, for read and write. + +In addition, the oflags contain information needed in the creation of a +message queue. ``O_NONBLOCK`` - If the non-block flag is set then the +message queue is non-blocking, and requests to send and receive messages +do not block waiting for resources. If the flag is not set then the +message queue is blocking, and a request to send might have to wait for an +empty message queue. Similarly, a request to receive might have to wait +for a message to arrive on the queue. ``O_CREAT`` - This call specifies +that the call the mq_open is to create a new message queue. In this case +the mode and attribute arguments of the function call are utilized. The +message queue is created with a mode similar to the creation of a file, +read and write permission creator, group, and others. + +The geometry of the message queue is contained in the attribute structure. +This includes mq_msgsize that dictates the maximum size of a single +message, and the mq_maxmsg that dictates the maximum number of messages +the queue can hold at one time. If a NULL is used in the mq_attr +argument, then the message queue is created with implementation defined +defaults. ``O_EXCL`` - is always set if O_CREAT flag is set. If the +message queue already exists, O_EXCL causes an error message to be +returned, otherwise, the new message queue fails and appends to the +existing one. + +**NOTES:** + +The mq_open () function does not add or remove messages from the queue. +When a new message queue is being created, the mq_flag field of the +attribute structure is not used. + +mq_close - Close a Message Queue +-------------------------------- +.. index:: mq_close +.. index:: close a message queue + +**CALLING SEQUENCE:** + +.. code:: c + + #include <mqueue.h> + int mq_close( + mqd_t mqdes + ); + +**STATUS CODES:** + +``EINVAL`` - The descriptor does not represent a valid open message +queue + +**DESCRIPTION:** + +The mq_close function removes the association between the message queue +descriptor, mqdes, and its message queue. If mq_close() is successfully +completed, the function returns a value of zero; otherwise, the function +returns a value of -1 and sets errno to indicate the error. + +**NOTES:** + +If the process had successfully attached a notification request to the +message queue via mq_notify, this attachment is removed, and the message +queue is available for another process to attach for notification. +mq_close has no effect on the contents of the message queue, all the +messages that were in the queue remain in the queue. + +mq_unlink - Remove a Message Queue +---------------------------------- +.. index:: mq_unlink +.. index:: remove a message queue + +**CALLING SEQUENCE:** + +.. code:: c + + #include <mqueue.h> + int mq_unlink( + const char \*name + ); + +**STATUS CODES:** + +``EINVAL`` - The descriptor does not represent a valid message queue + +**DESCRIPTION:** + +The mq_unlink() function removes the named message queue. If the message +queue is not open when mq_unlink is called, then the queue is immediately +eliminated. Any messages that were on the queue are lost, and the queue +can not be opened again. If processes have the queue open when mq_unlink +is called, the removal of the queue is delayed until the last process +using the queue has finished. However, the name of the message queue is +removed so that no other process can open it. Upon successful completion, +the function returns a value of zero. Otherwise, the named message queue +is not changed by this function call, and the function returns a value of +-1 and sets errno to indicate the error. + +**NOTES:** + +Calls to mq_open() to re-create the message queue may fail until the +message queue is actually removed. However, the mq_unlink() call need not +block until all references have been closed; it may return immediately. + +mq_send - Send a Message to a Message Queue +------------------------------------------- +.. index:: mq_send +.. index:: send a message to a message queue + +**CALLING SEQUENCE:** + +.. code:: c + + #include<mqueue.h> + int mq_send( + mqd_t mqdes, + const char \*msg_ptr, + size_t msg_len, + unsigned int msg_prio + ); + +**STATUS CODES:** + +``EBADF`` - The descriptor does not represent a valid message queue, or the queue was opened for read only O_RDONLY``EINVAL`` - The value of msg_prio was greater than the MQ_PRIO_MAX.``EMSGSIZE`` - The msg_len is greater than the mq_msgsize attribute of the message queue``EAGAIN`` - The message queue is non-blocking, and there is no room on the queue for another message as specified by the mq_maxmsg.``EINTR`` - The message queue is blocking. While the process was waiting for free space on the queue, a signal arrived that interrupted the wait. + +**DESCRIPTION:** + +The mq_send() function adds the message pointed to by the argument msg_ptr +to the message queue specified by mqdes. Each message is assigned a +priority , from 0 to MQ_PRIO_MAX. MQ_PRIO_MAX is defined in <limits.h> and +must be at least 32. Messages are added to the queue in order of their +priority. The highest priority message is at the front of the queue. + +The maximum number of messages that a message queue may accept is +specified at creation by the mq_maxmsg field of the attribute structure. +If this amount is exceeded, the behavior of the process is determined +according to what oflag was used when the message queue was opened. If +the queue was opened with O_NONBLOCK flag set, then the EAGAIN error is +returned. If the O_NONBLOCK flag was not set, the process blocks and +waits for space on the queue, unless it is interrupted by a signal. + +Upon successful completion, the mq_send () function returns a value of +zero. Otherwise, no message is enqueued, the function returns -1, and +errno is set to indicate the error. + +**NOTES:** + +If the specified message queue is not full, mq_send inserts the message at +the position indicated by the msg_prio argument. + +mq_receive - Receive a Message from a Message Queue +--------------------------------------------------- +.. index:: mq_receive +.. index:: receive a message from a message queue + +**CALLING SEQUENCE:** + +.. code:: c + + #include <mqueue.h> + size_t mq_receive( + mqd_t mqdes, + char \*msg_ptr, + size_t msg_len, + unsigned int \*msg_prio + ); + +**STATUS CODES:** + +``EBADF`` - The descriptor does not represent a valid message queue, or the queue was opened for write only O_WRONLY``EMSGSIZE`` - The msg_len is less than the mq_msgsize attribute of the message queue``EAGAIN`` - The message queue is non-blocking, and the queue is empty``EINTR`` - The message queue is blocking. While the process was waiting for a message to arrive on the queue, a signal arrived that interrupted the wait. + +**DESCRIPTION:** + +The mq_receive function is used to receive the oldest of the highest +priority message(s) from the message queue specified by mqdes. The +messages are received in FIFO order within the priorities. The received +message’s priority is stored in the location referenced by the msg_prio. +If the msg_prio is a NULL, the priority is discarded. The message is +removed and stored in an area pointed to by msg_ptr whose length is of +msg_len. The msg_len must be at least equal to the mq_msgsize attribute +of the message queue. + +The blocking behavior of the message queue is set by O_NONBLOCK at mq_open +or by setting O_NONBLOCK in mq_flags in a call to mq_setattr. If this is +a blocking queue, the process blocks and waits on an empty queue. If this +a non-blocking queue, the process does not block. + +Upon successful completion, mq_receive returns the length of the selected +message in bytes and the message is removed from the queue. Otherwise, no +message is removed from the queue, the function returns a value of -1, and +sets errno to indicate the error. + +**NOTES:** + +If the size of the buffer in bytes, specified by the msg_len argument, is +less than the mq_msgsize attribute of the message queue, the function +fails and returns an error + +mq_notify - Notify Process that a Message is Available +------------------------------------------------------ +.. index:: mq_notify +.. index:: notify process that a message is available + +**CALLING SEQUENCE:** + +.. code:: c + + #include <mqueue.h> + int mq_notify( + mqd_t mqdes, + const struct sigevent \*notification + ); + +**STATUS CODES:** + +``EBADF`` - The descriptor does not refer to a valid message queue``EBUSY`` - A notification request is already attached to the queue + +**DESCRIPTION:** + +If the argument notification is not NULL, this function registers the +calling process to be notified of message arrival at an empty message +queue associated with the specified message queue descriptor, mqdes. + +Every message queue has the ability to notify one (and only one) process +whenever the queue’s state changes from empty (0 messages) to nonempty. +This means that the process does not have to block or constantly poll +while it waits for a message. By calling mq_notify, a notification +request is attached to a message queue. When a message is received by an +empty queue, if there are no processes blocked and waiting for the +message, then the queue notifies the requesting process of a message +arrival. There is only one signal sent by the message queue, after that +the notification request is de-registered and another process can attach +its notification request. After receipt of a notification, a process must +re-register if it wishes to be notified again. + +If there is a process blocked and waiting for the message, that process +gets the message, and notification is not be sent. Only one process can +have a notification request attached to a message queue at any one time. +If another process attempts to register a notification request, it fails. +You can de-register for a message queue by passing a NULL to mq_notify; +this removes any notification request attached to the queue. Whenever the +message queue is closed, all notification attachments are removed. + +Upon successful completion, mq_notify returns a value of zero; otherwise, +the function returns a value of -1 and sets errno to indicate the error. + +**NOTES:** + +It is possible for another process to receive the message after the notification is sent but before the notified process has sent its receive request. + +mq_setattr - Set Message Queue Attributes +----------------------------------------- +.. index:: mq_setattr +.. index:: set message queue attributes + +**CALLING SEQUENCE:** + +.. code:: c + + #include <mqueue.h> + int mq_setattr( + mqd_t mqdes, + const struct mq_attr \*mqstat, + struct mq_attr \*omqstat + ); + +**STATUS CODES:** + +``EBADF`` - The message queue descriptor does not refer to a valid, open queue.``EINVAL`` - The mq_flag value is invalid. + +**DESCRIPTION:** + +The mq_setattr function is used to set attributes associated with the open +message queue description referenced by the message queue descriptor +specified by mqdes. The \*omqstat represents the old or previous +attributes. If omqstat is non-NULL, the function mq_setattr() stores, in +the location referenced by omqstat, the previous message queue attributes +and the current queue status. These values are the same as would be +returned by a call to mq_getattr() at that point. + +There is only one mq_attr.mq_flag which can be altered by this call. +This is the flag that deals with the blocking and non-blocking behavior of +the message queue. If the flag is set then the message queue is +non-blocking, and requests to send or receive do not block while waiting +for resources. If the flag is not set, then message send and receive may +involve waiting for an empty queue or waiting for a message to arrive. + +Upon successful completion, the function returns a value of zero and the +attributes of the message queue have been changed as specified. +Otherwise, the message queue attributes is unchanged, and the function +returns a value of -1 and sets errno to indicate the error. + +**NOTES:** + +All other fields in the mq_attr are ignored by this call. + +mq_getattr - Get Message Queue Attributes +----------------------------------------- +.. index:: mq_getattr +.. index:: get message queue attributes + +**CALLING SEQUENCE:** + +.. code:: c + + #include <mqueue.h> + int mq_getattr( + mqd_t mqdes, + struct mq_attr \*mqstat + ); + +**STATUS CODES:** + +``EBADF`` - The message queue descriptor does not refer to a valid, +open message queue. + +**DESCRIPTION:** + +The mqdes argument specifies a message queue descriptor. The mq_getattr +function is used to get status information and attributes of the message +queue associated with the message queue descriptor. The results are +returned in the mq_attr structure referenced by the mqstat argument. All +of these attributes are set at create time, except the +blocking/non-blocking behavior of the message queue which can be +dynamically set by using mq_setattr. The attribute mq_curmsg is set to +reflect the number of messages on the queue at the time that mq_getattr +was called. + +Upon successful completion, the mq_getattr function returns zero. +Otherwise, the function returns -1 and sets errno to indicate the error. + +**NOTES:** + +.. COMMENT: COPYRIGHT (c) 1988-2014. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/mutex.rst b/posix_users/mutex.rst new file mode 100644 index 0000000..067f284 --- /dev/null +++ b/posix_users/mutex.rst @@ -0,0 +1,626 @@ +Mutex Manager +############# + +Introduction +============ + +The mutex manager implements the functionality required of the mutex +manager as defined by POSIX 1003.1b-1996. This standard requires that +a compliant operating system provide the facilties to ensure that +threads can operate with mutual exclusion from one another and +defines the API that must be provided. + +The services provided by the mutex manager are: + +- ``pthread_mutexattr_init`` - Initialize a Mutex Attribute Set + +- ``pthread_mutexattr_destroy`` - Destroy a Mutex Attribute Set + +- ``pthread_mutexattr_setprotocol`` - Set the Blocking Protocol + +- ``pthread_mutexattr_getprotocol`` - Get the Blocking Protocol + +- ``pthread_mutexattr_setprioceiling`` - Set the Priority Ceiling + +- ``pthread_mutexattr_getprioceiling`` - Get the Priority Ceiling + +- ``pthread_mutexattr_setpshared`` - Set the Visibility + +- ``pthread_mutexattr_getpshared`` - Get the Visibility + +- ``pthread_mutex_init`` - Initialize a Mutex + +- ``pthread_mutex_destroy`` - Destroy a Mutex + +- ``pthread_mutex_lock`` - Lock a Mutex + +- ``pthread_mutex_trylock`` - Poll to Lock a Mutex + +- ``pthread_mutex_timedlock`` - Lock a Mutex with Timeout + +- ``pthread_mutex_unlock`` - Unlock a Mutex + +- ``pthread_mutex_setprioceiling`` - Dynamically Set the Priority Ceiling + +- ``pthread_mutex_getprioceiling`` - Dynamically Get the Priority Ceiling + +Background +========== + +Mutex Attributes +---------------- + +Mutex attributes are utilized only at mutex creation time. A mutex +attribute structure may be initialized and passed as an argument to +the ``mutex_init`` routine. Note that the priority ceiling of +a mutex may be set at run-time. + +*blocking protcol* + is the XXX + +*priority ceiling* + is the XXX + +*pshared* + is the XXX + +PTHREAD_MUTEX_INITIALIZER +------------------------- + +This is a special value that a variable of type ``pthread_mutex_t`` +may be statically initialized to as shown below: +.. code:: c + + pthread_mutex_t my_mutex = PTHREAD_MUTEX_INITIALIZER; + +This indicates that ``my_mutex`` will be automatically initialized +by an implicit call to ``pthread_mutex_init`` the first time +the mutex is used. + +Note that the mutex will be initialized with default attributes. + +Operations +========== + +There is currently no text in this section. + +Services +======== + +This section details the mutex manager’s services. +A subsection is dedicated to each of this manager’s services +and describes the calling sequence, related constants, usage, +and status codes. + +pthread_mutexattr_init - Initialize a Mutex Attribute Set +--------------------------------------------------------- +.. index:: pthread_mutexattr_init +.. index:: initialize a mutex attribute set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_init( + pthread_mutexattr_t \*attr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_mutexattr_init`` routine initializes the mutex attributes +object specified by ``attr`` with the default value for all of the +individual attributes. + +**NOTES:** + +XXX insert list of default attributes here. + +pthread_mutexattr_destroy - Destroy a Mutex Attribute Set +--------------------------------------------------------- +.. index:: pthread_mutexattr_destroy +.. index:: destroy a mutex attribute set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_destroy( + pthread_mutexattr_t \*attr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +**DESCRIPTION:** + +The ``pthread_mutex_attr_destroy`` routine is used to destroy a mutex +attributes object. The behavior of using an attributes object after +it is destroyed is implementation dependent. + +**NOTES:** + +NONE + +pthread_mutexattr_setprotocol - Set the Blocking Protocol +--------------------------------------------------------- +.. index:: pthread_mutexattr_setprotocol +.. index:: set the blocking protocol + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_setprotocol( + pthread_mutexattr_t \*attr, + int protocol + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The protocol argument is invalid. + +**DESCRIPTION:** + +The ``pthread_mutexattr_setprotocol`` routine is used to set value of the``protocol`` attribute. This attribute controls the order in which +threads waiting on this mutex will receive it. + +The ``protocol`` can be one of the following: + +*``PTHREAD_PRIO_NONE``* + in which case blocking order is FIFO. + +*``PTHREAD_PRIO_INHERIT``* + in which case blocking order is priority with the priority inheritance + protocol in effect. + +*``PTHREAD_PRIO_PROTECT``* + in which case blocking order is priority with the priority ceiling + protocol in effect. + +**NOTES:** + +There is currently no way to get simple priority blocking ordering +with POSIX mutexes even though this could easily by supported by RTEMS. + +pthread_mutexattr_getprotocol - Get the Blocking Protocol +--------------------------------------------------------- +.. index:: pthread_mutexattr_getprotocol +.. index:: get the blocking protocol + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_getprotocol( + pthread_mutexattr_t \*attr, + int \*protocol + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The protocol pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_mutexattr_getprotocol`` routine is used to obtain +the value of the ``protocol`` attribute. This attribute controls +the order in which threads waiting on this mutex will receive it. + +**NOTES:** + +NONE + +pthread_mutexattr_setprioceiling - Set the Priority Ceiling +----------------------------------------------------------- +.. index:: pthread_mutexattr_setprioceiling +.. index:: set the priority ceiling + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_setprioceiling( + pthread_mutexattr_t \*attr, + int prioceiling + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The prioceiling argument is invalid. + +**DESCRIPTION:** + +The ``pthread_mutexattr_setprioceiling`` routine is used to set value of the``prioceiling`` attribute. This attribute specifies the priority that +is the ceiling for threads obtaining this mutex. Any task obtaining this +mutex may not be of greater priority that the ceiling. If it is of lower +priority, then its priority will be elevated to ``prioceiling``. + +**NOTES:** + +NONE + +pthread_mutexattr_getprioceiling - Get the Priority Ceiling +----------------------------------------------------------- +.. index:: pthread_mutexattr_getprioceiling +.. index:: get the priority ceiling + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_getprioceiling( + const pthread_mutexattr_t \*attr, + int \*prioceiling + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The prioceiling pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_mutexattr_getprioceiling`` routine is used to obtain the +value of the ``prioceiling`` attribute. This attribute specifies the +priority ceiling for this mutex. + +**NOTES:** + +NONE + +pthread_mutexattr_setpshared - Set the Visibility +------------------------------------------------- +.. index:: pthread_mutexattr_setpshared +.. index:: set the visibility + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_setpshared( + pthread_mutexattr_t \*attr, + int pshared + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The pshared argument is invalid. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutexattr_getpshared - Get the Visibility +------------------------------------------------- +.. index:: pthread_mutexattr_getpshared +.. index:: get the visibility + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutexattr_getpshared( + const pthread_mutexattr_t \*attr, + int \*pshared + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The pshared pointer argument is invalid. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_init - Initialize a Mutex +--------------------------------------- +.. index:: pthread_mutex_init +.. index:: initialize a mutex + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutex_init( + pthread_mutex_t \*mutex, + const pthread_mutexattr_t \*attr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The specified protocol is invalid. + +*EAGAIN* + The system lacked the necessary resources to initialize another mutex. + +*ENOMEM* + Insufficient memory exists to initialize the mutex. + +*EBUSY* + Attempted to reinialize the object reference by mutex, a previously + initialized, but not yet destroyed. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_destroy - Destroy a Mutex +--------------------------------------- +.. index:: pthread_mutex_destroy +.. index:: destroy a mutex + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutex_destroy( + pthread_mutex_t \*mutex + ); + +**STATUS CODES:** + +*EINVAL* + The specified mutex is invalid. + +*EBUSY* + Attempted to destroy the object reference by mutex, while it is locked or + referenced by another thread. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_lock - Lock a Mutex +--------------------------------- +.. index:: pthread_mutex_lock +.. index:: lock a mutex + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutex_lock( + pthread_mutex_t \*mutex + ); + +**STATUS CODES:** + +*EINVAL* + The specified mutex is invalid. + +*EINVAL* + The mutex has the protocol attribute of PTHREAD_PRIO_PROTECT and the + priority of the calling thread is higher than the current priority + ceiling. + +*EDEADLK* + The current thread already owns the mutex. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_trylock - Poll to Lock a Mutex +-------------------------------------------- +.. index:: pthread_mutex_trylock +.. index:: poll to lock a mutex + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutex_trylock( + pthread_mutex_t \*mutex + ); + +**STATUS CODES:** + +*EINVAL* + The specified mutex is invalid. + +*EINVAL* + The mutex has the protocol attribute of PTHREAD_PRIO_PROTECT and the + priority of the calling thread is higher than the current priority + ceiling. + +*EBUSY* + The mutex is already locked. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_timedlock - Lock a Mutex with Timeout +--------------------------------------------------- +.. index:: pthread_mutex_timedlock +.. index:: lock a mutex with timeout + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + #include <time.h> + int pthread_mutex_timedlock( + pthread_mutex_t \*mutex, + const struct timespec \*timeout + ); + +**STATUS CODES:** + +*EINVAL* + The specified mutex is invalid. + +*EINVAL* + The nanoseconds field of timeout is invalid. + +*EINVAL* + The mutex has the protocol attribute of PTHREAD_PRIO_PROTECT and the + priority of the calling thread is higher than the current priority + ceiling. + +*EDEADLK* + The current thread already owns the mutex. + +*ETIMEDOUT* + The calling thread was unable to obtain the mutex within the specified + timeout period. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_unlock - Unlock a Mutex +------------------------------------- +.. index:: pthread_mutex_unlock +.. index:: unlock a mutex + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutex_unlock( + pthread_mutex_t \*mutex + ); + +**STATUS CODES:** + +*EINVAL* + The specified mutex is invalid. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_setprioceiling - Dynamically Set the Priority Ceiling +------------------------------------------------------------------- +.. index:: pthread_mutex_setprioceiling +.. index:: dynamically set the priority ceiling + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutex_setprioceiling( + pthread_mutex_t \*mutex, + int prioceiling, + int \*oldceiling + ); + +**STATUS CODES:** + +*EINVAL* + The oldceiling pointer parameter is invalid. + +*EINVAL* + The prioceiling parameter is an invalid priority. + +*EINVAL* + The specified mutex is invalid. + +**DESCRIPTION:** + +**NOTES:** + +pthread_mutex_getprioceiling - Get the Current Priority Ceiling +--------------------------------------------------------------- +.. index:: pthread_mutex_getprioceiling +.. index:: get the current priority ceiling + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_mutex_getprioceiling( + pthread_mutex_t \*mutex, + int \*prioceiling + ); + +**STATUS CODES:** + +*EINVAL* + The prioceiling pointer parameter is invalid. + +*EINVAL* + The specified mutex is invalid. + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/preface.rst b/posix_users/preface.rst new file mode 100644 index 0000000..e8e71f3 --- /dev/null +++ b/posix_users/preface.rst @@ -0,0 +1,69 @@ +Preface +####### + +This is the User’s Guide for the POSIX API support +provided in RTEMS. + +The functionality described in this document is based +on the following standards: + +- POSIX 1003.1b-1993. + +- POSIX 1003.1h/D3. + +- Open Group Single UNIX Specification. + +Much of the POSIX API standard is actually implemented in the +Cygnus Newlib ANSI C Library. Please refer to documentation on +Newlib for more information on the functionality it supplies. + +This manual is still under construction and improvements +are welcomed from users. + +Acknowledgements +================ + +.. COMMENT: COPYRIGHT (c) 1988-2009. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + +.. COMMENT: The RTEMS Project has been granted permission from The Open Group + +.. COMMENT: IEEE to excerpt and use portions of the POSIX standards documents + +.. COMMENT: in the RTEMS POSIX API User's Guide and RTEMS Shell User's Guide. + +.. COMMENT: We have to include a specific acknowledgement paragraph in these + +.. COMMENT: documents (e.g. preface or copyright page) and another slightly + +.. COMMENT: different paragraph for each manual page that excerpts and uses + +.. COMMENT: text from the standards. + +.. COMMENT: This file should help ensure that the paragraphs are consistent + +.. COMMENT: and not duplicated + + The Institute of Electrical and Electronics Engineers, Inc and The + Open Group, have given us permission to reprint portions of their + documentation. + Portions of this text are reprinted and reproduced in electronic + form from IEEE Std 1003.1, 2004 Edition, Standard for Information + Technology â Operating System Interface (POSIX), The Open + Group Base Specifications Issue 6, Copyright © 2001-2004 by the + Institute of Electrical and Electronics Engineers, Inc and The + Open Group. In the event of any discrepancy between this version + and the original IEEE and The Open Group Standard, the original + IEEE and The Open Group Standard is the referee document. The + original Standard can be obtained online athttp://www.opengroup.org/unix/online.html. + This notice shall appear on any product containing this material. + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/process_creation_and_execution.rst b/posix_users/process_creation_and_execution.rst new file mode 100644 index 0000000..38f1ce1 --- /dev/null +++ b/posix_users/process_creation_and_execution.rst @@ -0,0 +1,374 @@ +Process Creation and Execution Manager +###################################### + +Introduction +============ + +The process creation and execution manager provides the +functionality associated with the creation and termination +of processes. + +The directives provided by the process creation and execution manager are: + +- ``fork`` - Create a Process + +- ``execl`` - Execute a File + +- ``execv`` - Execute a File + +- ``execle`` - Execute a File + +- ``execve`` - Execute a File + +- ``execlp`` - Execute a File + +- ``execvp`` - Execute a File + +- ``pthread_atfork`` - Register Fork Handlers + +- ``wait`` - Wait for Process Termination + +- ``waitpid`` - Wait for Process Termination + +- ``_exit`` - Terminate a Process + +Background +========== + +POSIX process functionality can not be completely +supported by RTEMS. This is because RTEMS provides no memory +protection and implements a *single process, multi-threaded +execution model*. In this light, RTEMS provides none of the +routines that are associated with the creation of new processes. +However, since the entire RTEMS application (e.g. executable) +is logically a single POSIX process, RTEMS is able to provide +implementations of many operations on processes. The rule of +thumb is that those routines provide a meaningful result. +For example, ``getpid()`` returns the node number. + +Operations +========== + +The only functionality method defined by this manager which is +supported by RTEMS is the ``_exit`` service. The +implementation of ``_exit`` shuts the application down and +is equivalent to invoking either ``exit`` or``rtems_shutdown_executive``. + +Directives +========== + +This section details the process creation and execution manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +fork - Create a Process +----------------------- +.. index:: fork +.. index:: create a process + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + int fork( void ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +execl - Execute a File +---------------------- +.. index:: execl +.. index:: execute a file + +**CALLING SEQUENCE:** + +.. code:: c + + int execl( + const char \*path, + const char \*arg, + ... + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +execv - Execute a File +---------------------- +.. index:: execv +.. index:: execute a file + +**CALLING SEQUENCE:** + +.. code:: c + + int execv( + const char \*path, + char const \*argv[], + ... + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +execle - Execute a File +----------------------- +.. index:: execle +.. index:: execute a file + +**CALLING SEQUENCE:** + +.. code:: c + + int execle( + const char \*path, + const char \*arg, + ... + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +execve - Execute a File +----------------------- +.. index:: execve +.. index:: execute a file + +**CALLING SEQUENCE:** + +.. code:: c + + int execve( + const char \*path, + char \*const argv[], + char \*const envp[] + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +execlp - Execute a File +----------------------- +.. index:: execlp +.. index:: execute a file + +**CALLING SEQUENCE:** + +.. code:: c + + int execlp( + const char \*file, + const char \*arg, + ... + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +execvp - Execute a File +----------------------- +.. index:: execvp +.. index:: execute a file + +**CALLING SEQUENCE:** + +.. code:: c + + int execvp( + const char \*file, + char \*const argv[] + ... + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +pthread_atfork - Register Fork Handlers +--------------------------------------- +.. index:: pthread_atfork +.. index:: register fork handlers + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + int pthread_atfork( + void (\*prepare)(void), + void (\*parent)(void), + void (\*child)(void) + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +wait - Wait for Process Termination +----------------------------------- +.. index:: wait +.. index:: wait for process termination + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <sys/wait.h> + int wait( + int \*stat_loc + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +waitpid - Wait for Process Termination +-------------------------------------- +.. index:: waitpid +.. index:: wait for process termination + +**CALLING SEQUENCE:** + +.. code:: c + + int wait( + pid_t pid, + int \*stat_loc, + int options + ); + +**STATUS CODES:** + +*ENOSYS* + This routine is not supported by RTEMS. + +**DESCRIPTION:** + +This routine is not supported by RTEMS. + +**NOTES:** + +NONE + +_exit - Terminate a Process +--------------------------- +.. index:: _exit +.. index:: terminate a process + +**CALLING SEQUENCE:** + +.. code:: c + + void _exit( + int status + ); + +**STATUS CODES:** + +NONE + +**DESCRIPTION:** + +The ``_exit()`` function terminates the calling process. + +**NOTES:** + +In RTEMS, a process is equivalent to the entire application on a single +processor. Invoking this service terminates the application. + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/process_environment.rst b/posix_users/process_environment.rst new file mode 100644 index 0000000..0deee9d --- /dev/null +++ b/posix_users/process_environment.rst @@ -0,0 +1,765 @@ +Process Environment Manager +########################### + +Introduction +============ + +The process environment manager is responsible for providing the +functions related to user and group Id management. + +The directives provided by the process environment manager are: + +- ``getpid`` - Get Process ID + +- ``getppid`` - Get Parent Process ID + +- ``getuid`` - Get User ID + +- ``geteuid`` - Get Effective User ID + +- ``getgid`` - Get Real Group ID + +- ``getegid`` - Get Effective Group ID + +- ``setuid`` - Set User ID + +- ``setgid`` - Set Group ID + +- ``getgroups`` - Get Supplementary Group IDs + +- ``getlogin`` - Get User Name + +- ``getlogin_r`` - Reentrant Get User Name + +- ``getpgrp`` - Get Process Group ID + +- ``setsid`` - Create Session and Set Process Group ID + +- ``setpgid`` - Set Process Group ID for Job Control + +- ``uname`` - Get System Name + +- ``times`` - Get Process Times + +- ``getenv`` - Get Environment Variables + +- ``setenv`` - Set Environment Variables + +- ``ctermid`` - Generate Terminal Pathname + +- ``ttyname`` - Determine Terminal Device Name + +- ``ttyname_r`` - Reentrant Determine Terminal Device Name + +- ``isatty`` - Determine if File Descriptor is Terminal + +- ``sysconf`` - Get Configurable System Variables + +Background +========== + +Users and Groups +---------------- + +RTEMS provides a single process, multi-threaded execution environment. +In this light, the notion of user and group is somewhat without meaning. +But RTEMS does provide services to provide a synthetic version of +user and group. By default, a single user and group is associated +with the application. Thus unless special actions are taken, +every thread in the application shares the same user and group Id. +The initial rationale for providing user and group Id functionality +in RTEMS was for the filesystem infrastructure to implement +file permission checks. The effective user/group Id capability +has since been used to implement permissions checking by +the ``ftpd`` server. + +In addition to the "real" user and group Ids, a process may +have an effective user/group Id. This allows a process to +function using a more limited permission set for certain operations. + +User and Group Names +-------------------- + +POSIX considers user and group Ids to be a unique integer that +may be associated with a name. This is usually accomplished +via a file named ``/etc/passwd`` for user Id mapping and``/etc/groups`` for group Id mapping. Again, although +RTEMS is effectively a single process and thus single user +system, it provides limited support for user and group +names. When configured with an appropriate filesystem, RTEMS +will access the appropriate files to map user and group Ids +to names. + +If these files do not exist, then RTEMS will synthesize +a minimal version so this family of services return without +error. It is important to remember that a design goal of +the RTEMS POSIX services is to provide useable and +meaningful results even though a full process model +is not available. + +Environment Variables +--------------------- + +POSIX allows for variables in the run-time environment. These are +name/value pairs that make be dynamically set and obtained by +programs. In a full POSIX environment with command line shell +and multiple processes, environment variables may be set in +one process – such as the shell – and inherited by child +processes. In RTEMS, there is only one process and thus +only one set of environment variables across all processes. + +Operations +========== + +Accessing User and Group Ids +---------------------------- + +The user Id associated with the current thread may be obtain +using the ``getuid()`` service. Similarly, the group Id +may be obtained using the ``getgid()`` service. + +Accessing Environment Variables +------------------------------- + +The value associated with an environment variable may be +obtained using the ``getenv()`` service and set using +the ``putenv()`` service. + +Directives +========== + +This section details the process environment manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +getpid - Get Process ID +----------------------- +.. index:: getpid +.. index:: get process id + +**CALLING SEQUENCE:** + +.. code:: c + + int getpid( void ); + +**STATUS CODES:** + +The process Id is returned. + +**DESCRIPTION:** + +This service returns the process Id. + +**NOTES:** + +NONE + +getppid - Get Parent Process ID +------------------------------- +.. index:: getppid +.. index:: get parent process id + +**CALLING SEQUENCE:** + +.. code:: c + + int getppid( void ); + +**STATUS CODES:** + +The parent process Id is returned. + +**DESCRIPTION:** + +This service returns the parent process Id. + +**NOTES:** + +NONE + +getuid - Get User ID +-------------------- +.. index:: getuid +.. index:: get user id + +**CALLING SEQUENCE:** + +.. code:: c + + int getuid( void ); + +**STATUS CODES:** + +The effective user Id is returned. + +**DESCRIPTION:** + +This service returns the effective user Id. + +**NOTES:** + +NONE + +geteuid - Get Effective User ID +------------------------------- +.. index:: geteuid +.. index:: get effective user id + +**CALLING SEQUENCE:** + +.. code:: c + + int geteuid( void ); + +**STATUS CODES:** + +The effective group Id is returned. + +**DESCRIPTION:** + +This service returns the effective group Id. + +**NOTES:** + +NONE + +getgid - Get Real Group ID +-------------------------- +.. index:: getgid +.. index:: get real group id + +**CALLING SEQUENCE:** + +.. code:: c + + int getgid( void ); + +**STATUS CODES:** + +The group Id is returned. + +**DESCRIPTION:** + +This service returns the group Id. + +**NOTES:** + +NONE + +getegid - Get Effective Group ID +-------------------------------- +.. index:: getegid +.. index:: get effective group id + +**CALLING SEQUENCE:** + +.. code:: c + + int getegid( void ); + +**STATUS CODES:** + +The effective group Id is returned. + +**DESCRIPTION:** + +This service returns the effective group Id. + +**NOTES:** + +NONE + +setuid - Set User ID +-------------------- +.. index:: setuid +.. index:: set user id + +**CALLING SEQUENCE:** + +.. code:: c + + int setuid( + uid_t uid + ); + +**STATUS CODES:** + +This service returns 0. + +**DESCRIPTION:** + +This service sets the user Id to ``uid``. + +**NOTES:** + +NONE + +setgid - Set Group ID +--------------------- +.. index:: setgid +.. index:: set group id + +**CALLING SEQUENCE:** + +.. code:: c + + int setgid( + gid_t gid + ); + +**STATUS CODES:** + +This service returns 0. + +**DESCRIPTION:** + +This service sets the group Id to ``gid``. + +**NOTES:** + +NONE + +getgroups - Get Supplementary Group IDs +--------------------------------------- +.. index:: getgroups +.. index:: get supplementary group ids + +**CALLING SEQUENCE:** + +.. code:: c + + int getgroups( + int gidsetsize, + gid_t grouplist[] + ); + +**STATUS CODES:** + +NA + +**DESCRIPTION:** + +This service is not implemented as RTEMS has no notion of +supplemental groups. + +**NOTES:** + +If supported, this routine would only be allowed for +the super-user. + +getlogin - Get User Name +------------------------ +.. index:: getlogin +.. index:: get user name + +**CALLING SEQUENCE:** + +.. code:: c + + char \*getlogin( void ); + +**STATUS CODES:** + +Returns a pointer to a string containing the name of the +current user. + +**DESCRIPTION:** + +This routine returns the name of the current user. + +**NOTES:** + +This routine is not reentrant and subsequent calls to``getlogin()`` will overwrite the same buffer. + +getlogin_r - Reentrant Get User Name +------------------------------------ +.. index:: getlogin_r +.. index:: reentrant get user name +.. index:: get user name, reentrant + +**CALLING SEQUENCE:** + +.. code:: c + + int getlogin_r( + char \*name, + size_t namesize + ); + +**STATUS CODES:** + +*EINVAL* + The arguments were invalid. + +**DESCRIPTION:** + +This is a reentrant version of the ``getlogin()`` service. The +caller specified their own buffer, ``name``, as well as the +length of this buffer, ``namesize``. + +**NOTES:** + +NONE + +getpgrp - Get Process Group ID +------------------------------ +.. index:: getpgrp +.. index:: get process group id + +**CALLING SEQUENCE:** + +.. code:: c + + pid_t getpgrp( void ); + +**STATUS CODES:** + +The procress group Id is returned. + +**DESCRIPTION:** + +This service returns the current progress group Id. + +**NOTES:** + +This routine is implemented in a somewhat meaningful +way for RTEMS but is truly not functional. + +setsid - Create Session and Set Process Group ID +------------------------------------------------ +.. index:: setsid +.. index:: create session and set process group id + +**CALLING SEQUENCE:** + +.. code:: c + + pid_t setsid( void ); + +**STATUS CODES:** + +*EPERM* + The application does not have permission to create a process group. + +**DESCRIPTION:** + +This routine always returns ``EPERM`` as RTEMS has no way +to create new processes and thus no way to create a new process +group. + +**NOTES:** + +NONE + +setpgid - Set Process Group ID for Job Control +---------------------------------------------- +.. index:: setpgid +.. index:: set process group id for job control + +**CALLING SEQUENCE:** + +.. code:: c + + int setpgid( + pid_t pid, + pid_t pgid + ); + +**STATUS CODES:** + +*ENOSYS* + The routine is not implemented. + +**DESCRIPTION:** + +This service is not implemented for RTEMS as process groups are not +supported. + +**NOTES:** + +NONE + +uname - Get System Name +----------------------- +.. index:: uname +.. index:: get system name + +**CALLING SEQUENCE:** + +.. code:: c + + int uname( + struct utsname \*name + ); + +**STATUS CODES:** + +*EPERM* + The provided structure pointer is invalid. + +**DESCRIPTION:** + +This service returns system information to the caller. It does this +by filling in the ``struct utsname`` format structure for the +caller. + +**NOTES:** + +The information provided includes the operating system (RTEMS in +all configurations), the node number, the release as the RTEMS +version, and the CPU family and model. The CPU model name +will indicate the multilib executive variant being used. + +times - Get process times +------------------------- +.. index:: times +.. index:: get process times + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/time.h> + clock_t times( + struct tms \*ptms + ); + +**STATUS CODES:** + +This routine returns the number of clock ticks that have elapsed +since the system was initialized (e.g. the application was +started). + +**DESCRIPTION:** + +``times`` stores the current process times in ``ptms``. The +format of ``struct tms`` is as defined in``<sys/times.h>``. RTEMS fills in the field ``tms_utime`` +with the number of ticks that the calling thread has executed +and the field ``tms_stime`` with the number of clock ticks +since system boot (also returned). All other fields in the``ptms`` are left zero. + +**NOTES:** + +RTEMS has no way to distinguish between user and system time +so this routine returns the most meaningful information +possible. + +getenv - Get Environment Variables +---------------------------------- +.. index:: getenv +.. index:: get environment variables + +**CALLING SEQUENCE:** + +.. code:: c + + char \*getenv( + const char \*name + ); + +**STATUS CODES:** + +*NULL* + when no match + +*pointer to value* + when successful + +**DESCRIPTION:** + +This service searches the set of environment variables for +a string that matches the specified ``name``. If found, +it returns the associated value. + +**NOTES:** + +The environment list consists of name value pairs that +are of the form *name = value*. + +setenv - Set Environment Variables +---------------------------------- +.. index:: setenv +.. index:: set environment variables + +**CALLING SEQUENCE:** + +.. code:: c + + int setenv( + const char \*name, + const char \*value, + int overwrite + ); + +**STATUS CODES:** + +Returns 0 if successful and -1 otherwise. + +**DESCRIPTION:** + +This service adds the variable ``name`` to the environment with``value``. If ``name`` is not already exist, then it is +created. If ``name`` exists and ``overwrite`` is zero, then +the previous value is not overwritten. + +**NOTES:** + +NONE + +ctermid - Generate Terminal Pathname +------------------------------------ +.. index:: ctermid +.. index:: generate terminal pathname + +**CALLING SEQUENCE:** + +.. code:: c + + char \*ctermid( + char \*s + ); + +**STATUS CODES:** + +Returns a pointer to a string indicating the pathname for the controlling +terminal. + +**DESCRIPTION:** + +This service returns the name of the terminal device associated with +this process. If ``s`` is NULL, then a pointer to a static buffer +is returned. Otherwise, ``s`` is assumed to have a buffer of +sufficient size to contain the name of the controlling terminal. + +**NOTES:** + +By default on RTEMS systems, the controlling terminal is ``/dev/console``. +Again this implementation is of limited meaning, but it provides +true and useful results which should be sufficient to ease porting +applications from a full POSIX implementation to the reduced +profile supported by RTEMS. + +ttyname - Determine Terminal Device Name +---------------------------------------- +.. index:: ttyname +.. index:: determine terminal device name + +**CALLING SEQUENCE:** + +.. code:: c + + char \*ttyname( + int fd + ); + +**STATUS CODES:** + +Pointer to a string containing the terminal device name or +NULL is returned on any error. + +**DESCRIPTION:** + +This service returns a pointer to the pathname of the terminal +device that is open on the file descriptor ``fd``. If``fd`` is not a valid descriptor for a terminal device, +then NULL is returned. + +**NOTES:** + +This routine uses a static buffer. + +ttyname_r - Reentrant Determine Terminal Device Name +---------------------------------------------------- +.. index:: ttyname_r +.. index:: reentrant determine terminal device name + +**CALLING SEQUENCE:** + +.. code:: c + + int ttyname_r( + int fd, + char \*name, + int namesize + ); + +**STATUS CODES:** + +This routine returns -1 and sets ``errno`` as follows: + +*EBADF* + If not a valid descriptor for a terminal device. + +*EINVAL* + If ``name`` is NULL or ``namesize`` are insufficient. + +**DESCRIPTION:** + +This service the pathname of the terminal device that is open +on the file descriptor ``fd``. + +**NOTES:** + +NONE + +isatty - Determine if File Descriptor is Terminal +------------------------------------------------- +.. index:: isatty +.. index:: determine if file descriptor is terminal + +**CALLING SEQUENCE:** + +.. code:: c + + int isatty( + int fd + ); + +**STATUS CODES:** + +Returns 1 if ``fd`` is a terminal device and 0 otherwise. + +**DESCRIPTION:** + +This service returns 1 if ``fd`` is an open file descriptor +connected to a terminal and 0 otherwise. + +**NOTES:** + +sysconf - Get Configurable System Variables +------------------------------------------- +.. index:: sysconf +.. index:: get configurable system variables + +**CALLING SEQUENCE:** + +.. code:: c + + long sysconf( + int name + ); + +**STATUS CODES:** + +The value returned is the actual value of the system resource. +If the requested configuration name is a feature flag, then +1 is returned if the available and 0 if it is not. On any +other error condition, -1 is returned. + +**DESCRIPTION:** + +This service is the mechanism by which an application determines +values for system limits or options at runtime. + +**NOTES:** + +Much of the information that may be obtained via ``sysconf`` +has equivalent macros in ``<unistd.h``. However, those +macros reflect conservative limits which may have been altered +by application configuration. + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/scheduler.rst b/posix_users/scheduler.rst new file mode 100644 index 0000000..6c115e4 --- /dev/null +++ b/posix_users/scheduler.rst @@ -0,0 +1,192 @@ +Scheduler Manager +################# + +Introduction +============ + +The scheduler manager ... + +The directives provided by the scheduler manager are: + +- ``sched_get_priority_min`` - Get Minimum Priority Value + +- ``sched_get_priority_max`` - Get Maximum Priority Value + +- ``sched_rr_get_interval`` - Get Timeslicing Quantum + +- ``sched_yield`` - Yield the Processor + +Background +========== + +Priority +-------- + +In the RTEMS implementation of the POSIX API, the priorities range from +the low priority of ``sched_get_priority_min()`` to the highest priority of``sched_get_priority_max()``. Numerically higher values represent higher +priorities. + +Scheduling Policies +------------------- + +The following scheduling policies are available: + +*SCHED_FIFO* + Priority-based, preemptive scheduling with no timeslicing. This is equivalent + to what is called "manual round-robin" scheduling. + +*SCHED_RR* + Priority-based, preemptive scheduling with timeslicing. Time quantums are + maintained on a per-thread basis and are not reset at each context switch. + Thus, a thread which is preempted and subsequently resumes execution will + attempt to complete the unused portion of its time quantum. + +*SCHED_OTHER* + Priority-based, preemptive scheduling with timeslicing. Time quantums are + maintained on a per-thread basis and are reset at each context switch. + +*SCHED_SPORADIC* + Priority-based, preemptive scheduling utilizing three additional parameters: + budget, replenishment period, and low priority. Under this policy, the + thread is allowed to execute for "budget" amount of time before its priority + is lowered to "low priority". At the end of each replenishment period, + the thread resumes its initial priority and has its budget replenished. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the scheduler manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +sched_get_priority_min - Get Minimum Priority Value +--------------------------------------------------- +.. index:: sched_get_priority_min +.. index:: get minimum priority value + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sched.h> + int sched_get_priority_min( + int policy + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets errno to one of the following: + +*EINVAL* + The indicated policy is invalid. + +**DESCRIPTION:** + +This routine return the minimum (numerically and logically lowest) priority +for the specified ``policy``. + +**NOTES:** + +NONE + +sched_get_priority_max - Get Maximum Priority Value +--------------------------------------------------- +.. index:: sched_get_priority_max +.. index:: get maximum priority value + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sched.h> + int sched_get_priority_max( + int policy + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets errno to one of the following: + +*EINVAL* + The indicated policy is invalid. + +**DESCRIPTION:** + +This routine return the maximum (numerically and logically highest) priority +for the specified ``policy``. + +**NOTES:** + +NONE + +sched_rr_get_interval - Get Timeslicing Quantum +----------------------------------------------- +.. index:: sched_rr_get_interval +.. index:: get timeslicing quantum + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sched.h> + int sched_rr_get_interval( + pid_t pid, + struct timespec \*interval + ); + +**STATUS CODES:** + +On error, this routine returns -1 and sets errno to one of the following: + +*ESRCH* + The indicated process id is invalid. + +*EINVAL* + The specified interval pointer parameter is invalid. + +**DESCRIPTION:** + +This routine returns the length of the timeslice quantum in the``interval`` parameter for the specified ``pid``. + +**NOTES:** + +The ``pid`` argument should be 0 to indicate the calling process. + +sched_yield - Yield the Processor +--------------------------------- +.. index:: sched_yield +.. index:: yield the processor + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sched.h> + int sched_yield( void ); + +**STATUS CODES:** + +This routine always returns zero to indicate success. + +**DESCRIPTION:** + +This call forces the calling thread to yield the processor to another +thread. Normally this is used to implement voluntary round-robin +task scheduling. + +**NOTES:** + +NONE + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/semaphore.rst b/posix_users/semaphore.rst new file mode 100644 index 0000000..eda5bcd --- /dev/null +++ b/posix_users/semaphore.rst @@ -0,0 +1,503 @@ +Semaphore Manager +################# + +Introduction +============ + +The semaphore manager provides functions to allocate, delete, and control +semaphores. This manager is based on the POSIX 1003.1 standard. + +The directives provided by the semaphore manager are: + +- ``sem_init`` - Initialize an unnamed semaphore + +- ``sem_destroy`` - Destroy an unnamed semaphore + +- ``sem_open`` - Open a named semaphore + +- ``sem_close`` - Close a named semaphore + +- ``sem_unlink`` - Remove a named semaphore + +- ``sem_wait`` - Lock a semaphore + +- ``sem_trywait`` - Lock a semaphore + +- ``sem_timedwait`` - Wait on a Semaphore for a Specified Time + +- ``sem_post`` - Unlock a semaphore + +- ``sem_getvalue`` - Get the value of a semeaphore + +Background +========== + +Theory +------ + +Semaphores are used for synchronization and mutual exclusion by indicating the +availability and number of resources. The task (the task which is returning +resources) notifying other tasks of an event increases the number of resources +held by the semaphore by one. The task (the task which will obtain resources) +waiting for the event decreases the number of resources held by the semaphore +by one. If the number of resources held by a semaphore is insufficient (namely +0), the task requiring resources will wait until the next time resources are +returned to the semaphore. If there is more than one task waiting for a +semaphore, the tasks will be placed in the queue. + +"sem_t" Structure +----------------- +.. index:: sem_t + +The ``sem_t`` structure is used to represent semaphores. It is passed as an +argument to the semaphore directives and is defined as follows: +.. code:: c + + typedef int sem_t; + +Building a Semaphore Attribute Set +---------------------------------- + +Operations +========== + +Using as a Binary Semaphore +--------------------------- + +Although POSIX supports mutexes, they are only visible between threads. To work +between processes, a binary semaphore must be used. + +Creating a semaphore with a limit on the count of 1 effectively restricts the +semaphore to being a binary semaphore. When the binary semaphore is available, +the count is 1. When the binary semaphore is unavailable, the count is 0. + +Since this does not result in a true binary semaphore, advanced binary features like the Priority Inheritance and Priority Ceiling Protocols are not available. + +There is currently no text in this section. + +Directives +========== + +This section details the semaphore manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +sem_init - Initialize an unnamed semaphore +------------------------------------------ +.. index:: sem_init +.. index:: initialize an unnamed semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_init( + sem_t \*sem, + int pshared, + unsigned int value + ); + +**STATUS CODES:** + +*EINVAL* + The value argument exceeds SEM_VALUE_MAX + +*ENOSPC* + A resource required to initialize the semaphore has been exhausted + The limit on semaphores (SEM_VALUE_MAX) has been reached + +*ENOSYS* + The function sem_init is not supported by this implementation + +*EPERM* + The process lacks appropriate privileges to initialize the semaphore + +**DESCRIPTION:** + +The sem_init function is used to initialize the unnamed semaphore referred to +by "sem". The value of the initialized semaphore is the parameter "value". The +semaphore remains valid until it is destroyed. + +ADD MORE HERE XXX + +**NOTES:** + +If the functions completes successfully, it shall return a value of zero. +Otherwise, it shall return a value of -1 and set "errno" to specify the error +that occurred. + +Multiprocessing is currently not supported in this implementation. + +sem_destroy - Destroy an unnamed semaphore +------------------------------------------ +.. index:: sem_destroy +.. index:: destroy an unnamed semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_destroy( + sem_t \*sem + ); + +**STATUS CODES:** + +*EINVAL* + The value argument exceeds SEM_VALUE_MAX + +*ENOSYS* + The function sem_init is not supported by this implementation + +*EBUSY* + There are currently processes blocked on the semaphore + +**DESCRIPTION:** + +The sem_destroy function is used to destroy an unnamed semaphore refered to by +"sem". sem_destroy can only be used on a semaphore that was created using +sem_init. + +**NOTES:** + +If the functions completes successfully, it shall return a value of zero. +Otherwise, it shall return a value of -1 and set "errno" to specify the error +that occurred. + +Multiprocessing is currently not supported in this implementation. + +sem_open - Open a named semaphore +--------------------------------- +.. index:: sem_open +.. index:: open a named semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_open( + const char \*name, + int oflag + ); + +**ARGUMENTS:** + +The following flag bit may be set in oflag: + +``O_CREAT`` - Creates the semaphore if it does not already exist. If O_CREAT +is set and the semaphore already exists then O_CREAT has no effect. Otherwise, +sem_open() creates a semaphore. The O_CREAT flag requires the third and fourth +argument: mode and value of type mode_t and unsigned int, respectively. + +``O_EXCL`` - If O_EXCL and O_CREAT are set, all call to sem_open() shall fail +if the semaphore name exists + +**STATUS CODES:** + +*EACCES* + Valid name specified but oflag permissions are denied, or the semaphore name + specified does not exist and permission to create the named semaphore is denied. + +*EEXIST* + O_CREAT and O_EXCL are set and the named semaphore already exists. + +*EINTR* + The sem_open() operation was interrupted by a signal. + +*EINVAL* + The sem_open() operation is not supported for the given name. + +*EMFILE* + Too many semaphore descriptors or file descriptors in use by this process. + +*ENAMETOOLONG* + The length of the name exceed PATH_MAX or name component is longer than NAME_MAX + while POSIX_NO_TRUNC is in effect. + +*ENOENT* + O_CREAT is not set and the named semaphore does not exist. + +*ENOSPC* + There is insufficient space for the creation of a new named semaphore. + +*ENOSYS* + The function sem_open() is not supported by this implementation. + +**DESCRIPTION:** + +The sem_open() function establishes a connection between a specified semaphore and +a process. After a call to sem_open with a specified semaphore name, a process +can reference to semaphore by the associated name using the address returned by +the call. The oflag arguments listed above control the state of the semaphore by +determining if the semaphore is created or accessed by a call to sem_open(). + +**NOTES:** + +sem_close - Close a named semaphore +----------------------------------- +.. index:: sem_close +.. index:: close a named semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_close( + sem_t \*sem_close + ); + +**STATUS CODES:** + +*EACCES* + The semaphore argument is not a valid semaphore descriptor. + +*ENOSYS* + The function sem_close is not supported by this implementation. + +**DESCRIPTION:** + +The sem_close() function is used to indicate that the calling process is finished +using the named semaphore indicated by sem. The function sem_close deallocates +any system resources that were previously allocated by a sem_open system call. If +sem_close() completes successfully it returns a 1, otherwise a value of -1 is +return and errno is set. + +**NOTES:** + +sem_unlink - Unlink a semaphore +------------------------------- +.. index:: sem_unlink +.. index:: unlink a semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_unlink( + const char \*name + ); + +**STATUS CODES:** + +*EACCESS* + Permission is denied to unlink a semaphore. + +*ENAMETOOLONG* + The length of the strong name exceed NAME_MAX while POSIX_NO_TRUNC is in effect. + +*ENOENT* + The name of the semaphore does not exist. + +*ENOSPC* + There is insufficient space for the creation of a new named semaphore. + +*ENOSYS* + The function sem_unlink is not supported by this implementation. + +**DESCRIPTION:** + +The sem_unlink() function shall remove the semaphore name by the string name. If +a process is currently accessing the name semaphore, the sem_unlink command has +no effect. If one or more processes have the semaphore open when the sem_unlink +function is called, the destruction of semaphores shall be postponed until all +reference to semaphore are destroyed by calls to sem_close, _exit(), or exec. +After all references have been destroyed, it returns immediately. + +If the termination is successful, the function shall return 0. Otherwise, a -1 +is returned and the errno is set. + +**NOTES:** + +sem_wait - Wait on a Semaphore +------------------------------ +.. index:: sem_wait +.. index:: wait on a semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_wait( + sem_t \*sem + ); + +**STATUS CODES:** + +*EINVAL* + The "sem" argument does not refer to a valid semaphore + +**DESCRIPTION:** + +This function attempts to lock a semaphore specified by ``sem``. If the +semaphore is available, then the semaphore is locked (i.e., the semaphore +value is decremented). If the semaphore is unavailable (i.e., the semaphore +value is zero), then the function will block until the semaphore becomes +available. It will then successfully lock the semaphore. The semaphore +remains locked until released by a ``sem_post()`` call. + +If the call is unsuccessful, then the function returns -1 and sets errno to the +appropriate error code. + +**NOTES:** + +Multiprocessing is not supported in this implementation. + +sem_trywait - Non-blocking Wait on a Semaphore +---------------------------------------------- +.. index:: sem_trywait +.. index:: non + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_trywait( + sem_t \*sem + ); + +**STATUS CODES:** + +*EAGAIN* + The semaphore is not available (i.e., the semaphore value is zero), so the + semaphore could not be locked. + +*EINVAL* + The ``sem`` argument does not refewr to a valid semaphore + +**DESCRIPTION:** + +This function attempts to lock a semaphore specified by ``sem``. If the +semaphore is available, then the semaphore is locked (i.e., the semaphore +value is decremented) and the function returns a value of 0. The semaphore +remains locked until released by a ``sem_post()`` call. If the semaphore +is unavailable (i.e., the semaphore value is zero), then the function will +return a value of -1 immediately and set ``errno`` to EAGAIN. + +If the call is unsuccessful, then the function returns -1 and sets``errno`` to the appropriate error code. + +**NOTES:** + +Multiprocessing is not supported in this implementation. + +sem_timedwait - Wait on a Semaphore for a Specified Time +-------------------------------------------------------- +.. index:: sem_timedwait +.. index:: wait on a semaphore for a specified time + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_timedwait( + sem_t \*sem, + const struct timespec \*abstime + ); + +**STATUS CODES:** + +*EAGAIN* + The semaphore is not available (i.e., the semaphore value is zero), so the + semaphore could not be locked. + +*EINVAL* + The ``sem`` argument does not refewr to a valid semaphore + +**DESCRIPTION:** + +This function attemtps to lock a semaphore specified by ``sem``, +and will wait for the semaphore until the absolute time specified by``abstime``. If the semaphore is available, then the semaphore is +locked (i.e., the semaphore value is decremented) and the function +returns a value of 0. The semaphore remains locked until released by +a ``sem_post()`` call. If the semaphore is unavailable, then the +function will wait for the semaphore to become available for the amount +of time specified by ``timeout``. + +If the semaphore does not become available within the interval specified by``timeout``, then the function returns -1 and sets ``errno`` to EAGAIN. +If any other error occurs, the function returns -1 and sets ``errno`` to +the appropriate error code. + +**NOTES:** + +Multiprocessing is not supported in this implementation. + +sem_post - Unlock a Semaphore +----------------------------- +.. index:: sem_post +.. index:: unlock a semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_post( + sem_t \*sem + ); + +**STATUS CODES:** + +*EINVAL* + The ``sem`` argument does not refer to a valid semaphore + +**DESCRIPTION:** + +This function attempts to release the semaphore specified by ``sem``. If +other tasks are waiting on the semaphore, then one of those tasks (which one +depends on the scheduler being used) is allowed to lock the semaphore and +return from its ``sem_wait()``, ``sem_trywait()``, or``sem_timedwait()`` call. If there are no other tasks waiting on the +semaphore, then the semaphore value is simply incremented. ``sem_post()`` +returns 0 upon successful completion. + +If an error occurs, the function returns -1 and sets ``errno`` to the +appropriate error code. + +**NOTES:** + +Multiprocessing is not supported in this implementation. + +sem_getvalue - Get the value of a semaphore +------------------------------------------- +.. index:: sem_getvalue +.. index:: get the value of a semaphore + +**CALLING SEQUENCE:** + +.. code:: c + + int sem_getvalue( + sem_t \*sem, + int \*sval + ); + +**STATUS CODES:** + +*EINVAL* + The "sem" argument does not refer to a valid semaphore + +*ENOSYS* + The function sem_getvalue is not supported by this implementation + +**DESCRIPTION:** + +The sem_getvalue functions sets the location referenced by the "sval" argument +to the value of the semaphore without affecting the state of the semaphore. The +updated value represents a semaphore value that occurred at some point during +the call, but is not necessarily the actual value of the semaphore when it +returns to the calling process. + +If "sem" is locked, the value returned by sem_getvalue will be zero or a +negative number whose absolute value is the number of processes waiting for the +semaphore at some point during the call. + +**NOTES:** + +If the functions completes successfully, it shall return a value of zero. +Otherwise, it shall return a value of -1 and set "errno" to specify the error +that occurred. + +.. COMMENT: COPYRIGHT (c) 1989-2008. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/services_provided_by_c.rst b/posix_users/services_provided_by_c.rst new file mode 100644 index 0000000..2389609 --- /dev/null +++ b/posix_users/services_provided_by_c.rst @@ -0,0 +1,433 @@ +Services Provided by C Library (libc) +##################################### + +Introduction +============ + +This section lists the routines that provided by the Newlib C Library. + +Standard Utility Functions (stdlib.h) +===================================== + +- ``abort`` - Abnormal termination of a program + +- ``abs`` - Integer absolute value (magnitude) + +- ``assert`` - Macro for Debugging Diagnostics + +- ``atexit`` - Request execution of functions at program exit + +- ``atof`` - String to double or float + +- ``atoi`` - String to integer + +- ``bsearch`` - Binary search + +- ``calloc`` - Allocate space for arrays + +- ``div`` - Divide two integers + +- ``ecvtbuf`` - Double or float to string of digits + +- ``ecvt`` - Double or float to string of digits (malloc result) + +- ``__env_lock`` - Lock environment list for getenv and setenv + +- ``gvcvt`` - Format double or float as string + +- ``exit`` - End program execution + +- ``getenv`` - Look up environment variable + +- ``labs`` - Long integer absolute value (magnitude) + +- ``ldiv`` - Divide two long integers + +- ``malloc`` - Allocate memory + +- ``realloc`` - Reallocate memory + +- ``free`` - Free previously allocated memory + +- ``mallinfo`` - Get information about allocated memory + +- ``__malloc_lock`` - Lock memory pool for malloc and free + +- ``mbstowcs`` - Minimal multibyte string to wide string converter + +- ``mblen`` - Minimal multibyte length + +- ``mbtowc`` - Minimal multibyte to wide character converter + +- ``qsort`` - Sort an array + +- ``rand`` - Pseudo-random numbers + +- ``strtod`` - String to double or float + +- ``strtol`` - String to long + +- ``strtoul`` - String to unsigned long + +- ``system`` - Execute command string + +- ``wcstombs`` - Minimal wide string to multibyte string converter + +- ``wctomb`` - Minimal wide character to multibyte converter + +Character Type Macros and Functions (ctype.h) +============================================= + +- ``isalnum`` - Alphanumeric character predicate + +- ``isalpha`` - Alphabetic character predicate + +- ``isascii`` - ASCII character predicate + +- ``iscntrl`` - Control character predicate + +- ``isdigit`` - Decimal digit predicate + +- ``islower`` - Lower-case character predicate + +- ``isprint`` - Printable character predicates (isprint, isgraph) + +- ``ispunct`` - Punctuation character predicate + +- ``isspace`` - Whitespace character predicate + +- ``isupper`` - Uppercase character predicate + +- ``isxdigit`` - Hexadecimal digit predicate + +- ``toascii`` - Force integers to ASCII range + +- ``tolower`` - Translate characters to lower case + +- ``toupper`` - Translate characters to upper case + +Input and Output (stdio.h) +========================== + +- ``clearerr`` - Clear file or stream error indicator + +- ``fclose`` - Close a file + +- ``feof`` - Test for end of file + +- ``ferror`` - Test whether read/write error has occurred + +- ``fflush`` - Flush buffered file output + +- ``fgetc`` - Get a character from a file or stream + +- ``fgetpos`` - Record position in a stream or file + +- ``fgets`` - Get character string from a file or stream + +- ``fiprintf`` - Write formatted output to file (integer only) + +- ``fopen`` - Open a file + +- ``fdopen`` - Turn an open file into a stream + +- ``fputc`` - Write a character on a stream or file + +- ``fputs`` - Write a character string in a file or stream + +- ``fread`` - Read array elements from a file + +- ``freopen`` - Open a file using an existing file descriptor + +- ``fseek`` - Set file position + +- ``fsetpos`` - Restore position of a stream or file + +- ``ftell`` - Return position in a stream or file + +- ``fwrite`` - Write array elements from memory to a file or stream + +- ``getc`` - Get a character from a file or stream (macro) + +- ``getchar`` - Get a character from standard input (macro) + +- ``gets`` - Get character string from standard input (obsolete) + +- ``iprintf`` - Write formatted output (integer only) + +- ``mktemp`` - Generate unused file name + +- ``perror`` - Print an error message on standard error + +- ``putc`` - Write a character on a stream or file (macro) + +- ``putchar`` - Write a character on standard output (macro) + +- ``puts`` - Write a character string on standard output + +- ``remove`` - Delete a file’s name + +- ``rename`` - Rename a file + +- ``rewind`` - Reinitialize a file or stream + +- ``setbuf`` - Specify full buffering for a file or stream + +- ``setvbuf`` - Specify buffering for a file or stream + +- ``siprintf`` - Write formatted output (integer only) + +- ``printf`` - Write formatted output + +- ``scanf`` - Scan and format input + +- ``tmpfile`` - Create a temporary file + +- ``tmpnam`` - Generate name for a temporary file + +- ``vprintf`` - Format variable argument list + +Strings and Memory (string.h) +============================= + +- ``bcmp`` - Compare two memory areas + +- ``bcopy`` - Copy memory regions + +- ``bzero`` - Initialize memory to zero + +- ``index`` - Search for character in string + +- ``memchr`` - Find character in memory + +- ``memcmp`` - Compare two memory areas + +- ``memcpy`` - Copy memory regions + +- ``memmove`` - Move possibly overlapping memory + +- ``memset`` - Set an area of memory + +- ``rindex`` - Reverse search for character in string + +- ``strcasecmp`` - Compare strings ignoring case + +- ``strcat`` - Concatenate strings + +- ``strchr`` - Search for character in string + +- ``strcmp`` - Character string compare + +- ``strcoll`` - Locale specific character string compare + +- ``strcpy`` - Copy string + +- ``strcspn`` - Count chars not in string + +- ``strerror`` - Convert error number to string + +- ``strlen`` - Character string length + +- ``strlwr`` - Convert string to lower case + +- ``strncasecmp`` - Compare strings ignoring case + +- ``strncat`` - Concatenate strings + +- ``strncmp`` - Character string compare + +- ``strncpy`` - Counted copy string + +- ``strpbrk`` - Find chars in string + +- ``strrchr`` - Reverse search for character in string + +- ``strspn`` - Find initial match + +- ``strstr`` - Find string segment + +- ``strtok`` - Get next token from a string + +- ``strupr`` - Convert string to upper case + +- ``strxfrm`` - Transform string + +Signal Handling (signal.h) +========================== + +- ``raise`` - Send a signal + +- ``signal`` - Specify handler subroutine for a signal + +Time Functions (time.h) +======================= + +- ``asctime`` - Format time as string + +- ``clock`` - Cumulative processor time + +- ``ctime`` - Convert time to local and format as string + +- ``difftime`` - Subtract two times + +- ``gmtime`` - Convert time to UTC (GMT) traditional representation + +- ``localtime`` - Convert time to local representation + +- ``mktime`` - Convert time to arithmetic representation + +- ``strftime`` - Flexible calendar time formatter + +- ``time`` - Get current calendar time (as single number) + +Locale (locale.h) +================= + +- ``setlocale`` - Select or query locale + +Reentrant Versions of Functions +=============================== + +- Equivalent for errno variable: + - ``errno_r`` - XXX + +- Locale functions: + - ``localeconv_r`` - XXX + - ``setlocale_r`` - XXX + +- Equivalents for stdio variables: + - ``stdin_r`` - XXX + - ``stdout_r`` - XXX + - ``stderr_r`` - XXX + +- Stdio functions: + - ``fdopen_r`` - XXX + - ``perror_r`` - XXX + - ``tempnam_r`` - XXX + - ``fopen_r`` - XXX + - ``putchar_r`` - XXX + - ``tmpnam_r`` - XXX + - ``getchar_r`` - XXX + - ``puts_r`` - XXX + - ``tmpfile_r`` - XXX + - ``gets_r`` - XXX + - ``remove_r`` - XXX + - ``vfprintf_r`` - XXX + - ``iprintf_r`` - XXX + - ``rename_r`` - XXX + - ``vsnprintf_r`` - XXX + - ``mkstemp_r`` - XXX + - ``snprintf_r`` - XXX + - ``vsprintf_r`` - XXX + - ``mktemp_t`` - XXX + - ``sprintf_r`` - XXX + +- Signal functions: + - ``init_signal_r`` - XXX + - ``signal_r`` - XXX + - ``kill_r`` - XXX + - ``_sigtramp_r`` - XXX + - ``raise_r`` - XXX + +- Stdlib functions: + - ``calloc_r`` - XXX + - ``mblen_r`` - XXX + - ``srand_r`` - XXX + - ``dtoa_r`` - XXX + - ``mbstowcs_r`` - XXX + - ``strtod_r`` - XXX + - ``free_r`` - XXX + - ``mbtowc_r`` - XXX + - ``strtol_r`` - XXX + - ``getenv_r`` - XXX + - ``memalign_r`` - XXX + - ``strtoul_r`` - XXX + - ``mallinfo_r`` - XXX + - ``mstats_r`` - XXX + - ``system_r`` - XXX + - ``malloc_r`` - XXX + - ``rand_r`` - XXX + - ``wcstombs_r`` - XXX + - ``malloc_r`` - XXX + - ``realloc_r`` - XXX + - ``wctomb_r`` - XXX + - ``malloc_stats_r`` - XXX + - ``setenv_r`` - XXX + +- String functions: + - ``strtok_r`` - XXX + +- System functions: + - ``close_r`` - XXX + - ``link_r`` - XXX + - ``unlink_r`` - XXX + - ``execve_r`` - XXX + - ``lseek_r`` - XXX + - ``wait_r`` - XXX + - ``fcntl_r`` - XXX + - ``open_r`` - XXX + - ``write_r`` - XXX + - ``fork_r`` - XXX + - ``read_r`` - XXX + - ``fstat_r`` - XXX + - ``sbrk_r`` - XXX + - ``gettimeofday_r`` - XXX + - ``stat_r`` - XXX + - ``getpid_r`` - XXX + - ``times_r`` - XXX + +- Time function: + - ``asctime_r`` - XXX + +Miscellaneous Macros and Functions +================================== + +- ``unctrl`` - Return printable representation of a character + +Variable Argument Lists +======================= + +- Stdarg (stdarg.h): + - ``va_start`` - XXX + - ``va_arg`` - XXX + - ``va_end`` - XXX + +- Vararg (varargs.h): + - ``va_alist`` - XXX + - ``va_start-trad`` - XXX + - ``va_arg-trad`` - XXX + - ``va_end-trad`` - XXX + +Reentrant System Calls +====================== + +- ``open_r`` - XXX + +- ``close_r`` - XXX + +- ``lseek_r`` - XXX + +- ``read_r`` - XXX + +- ``write_r`` - XXX + +- ``fork_r`` - XXX + +- ``wait_r`` - XXX + +- ``stat_r`` - XXX + +- ``fstat_r`` - XXX + +- ``link_r`` - XXX + +- ``unlink_r`` - XXX + +- ``sbrk_r`` - XXX + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/services_provided_by_math.rst b/posix_users/services_provided_by_math.rst new file mode 100644 index 0000000..d199469 --- /dev/null +++ b/posix_users/services_provided_by_math.rst @@ -0,0 +1,96 @@ +Services Provided by the Math Library (libm) +############################################ + +Introduction +============ + +This section lists the routines that provided by the Newlib Math Library +(libm). + +Standard Math Functions (math.h) +================================ + +- ``acos`` - Arccosine + +- ``acosh`` - Inverse hyperbolic cosine + +- ``asin`` - Arcsine + +- ``asinh`` - Inverse hyperbolic sine + +- ``atan`` - Arctangent + +- ``atan2`` - Arctangent of y/x + +- ``atanh`` - Inverse hyperbolic tangent + +- ``jN`` - Bessel functions (jN and yN) + +- ``cbrt`` - Cube root + +- ``copysign`` - Sign of Y and magnitude of X + +- ``cosh`` - Hyperbolic cosine + +- ``erf`` - Error function (erf and erfc) + +- ``exp`` - Exponential + +- ``expm1`` - Exponential of x and - 1 + +- ``fabs`` - Absolute value (magnitude) + +- ``floor`` - Floor and ceiling (floor and ceil) + +- ``fmod`` - Floating-point remainder (modulo) + +- ``frexp`` - Split floating-point number + +- ``gamma`` - Logarithmic gamma function + +- ``hypot`` - Distance from origin + +- ``ilogb`` - Get exponent + +- ``infinity`` - Floating infinity + +- ``isnan`` - Check type of number + +- ``ldexp`` - Load exponent + +- ``log`` - Natural logarithms + +- ``log10`` - Base 10 logarithms + +- ``log1p`` - Log of 1 + X + +- ``matherr`` - Modifiable math error handler + +- ``modf`` - Split fractional and integer parts + +- ``nan`` - Floating Not a Number + +- ``nextafter`` - Get next representable number + +- ``pow`` - X to the power Y + +- ``remainder`` - remainder of X divided by Y + +- ``scalbn`` - scalbn + +- ``sin`` - Sine or cosine (sin and cos) + +- ``sinh`` - Hyperbolic sine + +- ``sqrt`` - Positive square root + +- ``tan`` - Tangent + +- ``tanh`` - Hyperbolic tangent + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/signal.rst b/posix_users/signal.rst new file mode 100644 index 0000000..51b43ab --- /dev/null +++ b/posix_users/signal.rst @@ -0,0 +1,890 @@ +Signal Manager +############## + +Introduction +============ + +The signal manager provides the functionality associated with +the generation, delivery, and management of process-oriented +signals. + +The directives provided by the signal manager are: + +- ``sigaddset`` - Add a Signal to a Signal Set + +- ``sigdelset`` - Delete a Signal from a Signal Set + +- ``sigfillset`` - Fill a Signal Set + +- ``sigismember`` - Is Signal a Member of a Signal Set + +- ``sigemptyset`` - Empty a Signal Set + +- ``sigaction`` - Examine and Change Signal Action + +- ``pthread_kill`` - Send a Signal to a Thread + +- ``sigprocmask`` - Examine and Change Process Blocked Signals + +- ``pthread_sigmask`` - Examine and Change Thread Blocked Signals + +- ``kill`` - Send a Signal to a Process + +- ``sigpending`` - Examine Pending Signals + +- ``sigsuspend`` - Wait for a Signal + +- ``pause`` - Suspend Process Execution + +- ``sigwait`` - Synchronously Accept a Signal + +- ``sigwaitinfo`` - Synchronously Accept a Signal + +- ``sigtimedwait`` - Synchronously Accept a Signal with Timeout + +- ``sigqueue`` - Queue a Signal to a Process + +- ``alarm`` - Schedule Alarm + +- ``ualarm`` - Schedule Alarm in Microseconds + +Background +========== + +Signals +------- + +POSIX signals are an asynchronous event mechanism. Each process +and thread has a set of signals associated with it. Individual +signals may be enabled (e.g. unmasked) or blocked (e.g. ignored) +on both a per-thread and process level. Signals which are +enabled have a signal handler associated with them. When the +signal is generated and conditions are met, then the signal +handler is invoked in the proper process or thread context +asynchronous relative to the logical thread of execution. + +If a signal has been blocked when it is generated, then it +is queued and kept pending until the thread or process unblocks +the signal or explicitly checks for it. +Traditional, non-real-time POSIX signals do not queue. Thus +if a process or thread has blocked a particular signal, then +multiple occurrences of that signal are recorded as a +single occurrence of that signal. + +.. COMMENT: TODO: SIGRTMIN and SIGRTMAX ? + +One can check for the set of outstanding signals that have been +blocked. Services are provided to check for outstanding process +or thread directed signals. + +Signal Delivery +--------------- + +Signals which are directed at a thread are delivered to the specified thread. + +Signals which are directed at a process are delivered to a thread which +is selected based on the following algorithm: + +# If the action for this signal is currently ``SIG_IGN``, + then the signal is simply ignored. + +# If the currently executing thread has the signal unblocked, then + the signal is delivered to it. + +# If any threads are currently blocked waiting for this signal + (``sigwait()``), then the signal is delivered to the highest priority + thread waiting for this signal. + +# If any other threads are willing to accept delivery of the signal, then + the signal is delivered to the highest priority thread of this set. In the + event, multiple threads of the same priority are willing to accept this + signal, then priority is given first to ready threads, then to threads + blocked on calls which may be interrupted, and finally to threads blocked + on non-interruptible calls. + +# In the event the signal still can not be delivered, then it is left + pending. The first thread to unblock the signal (``sigprocmask()`` or``pthread_sigprocmask()``) or to wait for this signal + (``sigwait()``) will be the recipient of the signal. + +Operations +========== + +Signal Set Management +--------------------- + +Each process and each thread within that process has a set of +individual signals and handlers associated with it. Services +are provided to construct signal sets for the purposes of building +signal sets – type ``sigset_t`` – that are used to +provide arguments to the services that mask, unmask, and +check on pending signals. + +Blocking Until Signal Generation +-------------------------------- + +A thread may block until receipt of a signal. The "sigwait" +and "pause" families of functions block until the requested +signal is received or if using ``sigtimedwait()`` until the specified +timeout period has elapsed. + +Sending a Signal +---------------- + +This is accomplished +via one of a number of services that sends a signal to either a +process or thread. Signals may be directed at a process by +the service ``kill()`` or at a thread by the service``pthread_kill()`` + +Directives +========== + +This section details the signal manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +sigaddset - Add a Signal to a Signal Set +---------------------------------------- +.. index:: sigaddset +.. index:: add a signal to a signal set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigaddset( + sigset_t \*set, + int signo + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This function adds the signal ``signo`` to the specified signal ``set``. + +**NOTES:** + +The set must be initialized using either ``sigemptyset`` or ``sigfillset`` +before using this function. + +sigdelset - Delete a Signal from a Signal Set +--------------------------------------------- +.. index:: sigdelset +.. index:: delete a signal from a signal set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigdelset( + sigset_t \*set, + int signo + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This function deletes the signal specified by ``signo`` from the specified +signal ``set``. + +**NOTES:** + +The set must be initialized using either ``sigemptyset`` or ``sigfillset`` +before using this function. + +sigfillset - Fill a Signal Set +------------------------------ +.. index:: sigfillset +.. index:: fill a signal set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigfillset( + sigset_t \*set + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This function fills the specified signal ``set`` such that all +signals are set. + +sigismember - Is Signal a Member of a Signal Set +------------------------------------------------ +.. index:: sigismember +.. index:: is signal a member of a signal set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigismember( + const sigset_t \*set, + int signo + ); + +**STATUS CODES:** + +The function returns either 1 or 0 if completed successfully, otherwise it +returns -1 and sets ``errno`` to indicate the error. ``errno`` may be set +to: + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This function returns returns 1 if ``signo`` is a member of ``set`` +and 0 otherwise. + +**NOTES:** + +The set must be initialized using either ``sigemptyset`` or ``sigfillset`` +before using this function. + +sigemptyset - Empty a Signal Set +-------------------------------- +.. index:: sigemptyset +.. index:: empty a signal set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigemptyset( + sigset_t \*set + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This function initializes an empty signal set pointed to by ``set``. + +sigaction - Examine and Change Signal Action +-------------------------------------------- +.. index:: sigaction +.. index:: examine and change signal action + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigaction( + int sig, + const struct sigaction \*act, + struct sigaction \*oact + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +*ENOTSUP* + Realtime Signals Extension option not supported. + +**DESCRIPTION:** + +If the argument act is not a null pointer, it points to a structure specifying +the action to be associated with the specified signal. If the argument oact is +not a null pointer, the action previously associated with the signal is stored +in the location pointed to by the argument oact. If the argument act is a null +pointer, signal handling is unchanged; thus, the call can be used to enquire +about the current handling of a given signal. + +The structure ``sigaction`` has the following members: + +``void(\*)(int) sa_handler`` + Pointer to a signal-catching function or one of the macros SIG_IGN or SIG_DFL. + +``sigset_t sa_mask`` + Additional set of signals to be blocked during execution of signal-catching function. + +``int sa_flags`` + Special flags to affect behavior of signal. + +``void(\*)(int, siginfo_t*, void*) sa_sigaction`` + Alternative pointer to a signal-catching function. + +``sa_handler`` and ``sa_sigaction`` should never be used at the same time as their storage may overlap. + +If the ``SA_SIGINFO`` flag (see below) is set in ``sa_flags``, the``sa_sigaction`` field specifies a signal-catching function, otherwise``sa_handler`` specifies the action to be associated with the signal, which +may be a signal-catching function or one of the macros ``SIG_IGN`` or``SIG_DFN``. + +The following flags can be set in the ``sa_flags`` field: + +``SA_SIGINFO`` + If not set, the signal-catching function should be declared as ``void + func(int signo)`` and the address of the function should be set in``sa_handler``. If set, the signal-catching function should be declared as``void func(int signo, siginfo_t* info, void* context)`` and the address of + the function should be set in ``sa_sigaction``. + +The prototype of the ``siginfo_t`` structure is the following: +.. code:: c + + typedef struct + { + int si_signo; /* Signal number \*/ + int si_code; /* Cause of the signal \*/ + pid_t si_pid; /* Sending process ID \*/ + uid_t si_uid; /* Real user ID of sending process \*/ + void* si_addr; /* Address of faulting instruction \*/ + int si_status; /* Exit value or signal \*/ + union sigval + { + int sival_int; /* Integer signal value \*/ + void* sival_ptr; /* Pointer signal value \*/ + } si_value; /* Signal value \*/ + } + +**NOTES:** + +The signal number cannot be SIGKILL. + +pthread_kill - Send a Signal to a Thread +---------------------------------------- +.. index:: pthread_kill +.. index:: send a signal to a thread + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int pthread_kill( + pthread_t thread, + int sig + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*ESRCH* + The thread indicated by the parameter thread is invalid. + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This functions sends the specified signal ``sig`` to a thread referenced +to by ``thread``. + +If the signal code is ``0``, arguments are validated and no signal is sent. + +sigprocmask - Examine and Change Process Blocked Signals +-------------------------------------------------------- +.. index:: sigprocmask +.. index:: examine and change process blocked signals + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigprocmask( + int how, + const sigset_t \*set, + sigset_t \*oset + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This function is used to alter the set of currently blocked signals +on a process wide basis. A blocked signal will not be received by the +process. The behavior of this function is dependent on the value of``how`` which may be one of the following: + +``SIG_BLOCK`` + The set of blocked signals is set to the union of ``set`` and + those signals currently blocked. + +``SIG_UNBLOCK`` + The signals specific in ``set`` are removed from the currently + blocked set. + +``SIG_SETMASK`` + The set of currently blocked signals is set to ``set``. + +If ``oset`` is not ``NULL``, then the set of blocked signals prior to +this call is returned in ``oset``. If ``set`` is *NULL*, no change is +done, allowing to examine the set of currently blocked signals. + +**NOTES:** + +It is not an error to unblock a signal which is not blocked. + +In the current implementation of RTEMS POSIX API sigprocmask() is technically +mapped to pthread_sigmask(). + +pthread_sigmask - Examine and Change Thread Blocked Signals +----------------------------------------------------------- +.. index:: pthread_sigmask +.. index:: examine and change thread blocked signals + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int pthread_sigmask( + int how, + const sigset_t \*set, + sigset_t \*oset + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +This function is used to alter the set of currently blocked signals +for the calling thread. A blocked signal will not be received by the +process. The behavior of this function is dependent on the value of``how`` which may be one of the following: + +``SIG_BLOCK`` + The set of blocked signals is set to the union of ``set`` and + those signals currently blocked. + +``SIG_UNBLOCK`` + The signals specific in ``set`` are removed from the currently + blocked set. + +``SIG_SETMASK`` + The set of currently blocked signals is set to ``set``. + +If ``oset`` is not ``NULL``, then the set of blocked signals prior to +this call is returned in ``oset``. If ``set`` is *NULL*, no change is +done, allowing to examine the set of currently blocked signals. + +**NOTES:** + +It is not an error to unblock a signal which is not blocked. + +kill - Send a Signal to a Process +--------------------------------- +.. index:: kill +.. index:: send a signal to a process + +**CALLING SEQUENCE:** + +.. code:: c + + #include <sys/types.h> + #include <signal.h> + int kill( + pid_t pid, + int sig + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +*EPERM* + Process does not have permission to send the signal to any receiving process. + +*ESRCH* + The process indicated by the parameter pid is invalid. + +**DESCRIPTION:** + +This function sends the signal ``sig`` to the process ``pid``. + +**NOTES:** + +Since RTEMS is a single-process system, a signal can only be sent to the calling +process (i.e. the current node). + +sigpending - Examine Pending Signals +------------------------------------ +.. index:: sigpending +.. index:: examine pending signals + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigpending( + const sigset_t \*set + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EFAULT* + Invalid address for set. + +**DESCRIPTION:** + +This function allows the caller to examine the set of currently pending +signals. A pending signal is one which has been raised but is currently +blocked. The set of pending signals is returned in ``set``. + +sigsuspend - Wait for a Signal +------------------------------ +.. index:: sigsuspend +.. index:: wait for a signal + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigsuspend( + const sigset_t \*sigmask + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINTR* + Signal interrupted this function. + +**DESCRIPTION:** + +This function temporarily replaces the signal mask for the process +with that specified by ``sigmask`` and blocks the calling thread +until a signal is raised. + +pause - Suspend Process Execution +--------------------------------- +.. index:: pause +.. index:: suspend process execution + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int pause( void ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINTR* + Signal interrupted this function. + +**DESCRIPTION:** + +This function causes the calling thread to be blocked until an +unblocked signal is received. + +sigwait - Synchronously Accept a Signal +--------------------------------------- +.. index:: sigwait +.. index:: synchronously accept a signal + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigwait( + const sigset_t \*set, + int \*sig + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINVAL* + Invalid argument passed. + +*EINTR* + Signal interrupted this function. + +**DESCRIPTION:** + +This function selects a pending signal based on the set specified in``set``, atomically clears it from the set of pending signals, and +returns the signal number for that signal in ``sig``. + +sigwaitinfo - Synchronously Accept a Signal +------------------------------------------- +.. index:: sigwaitinfo +.. index:: synchronously accept a signal + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigwaitinfo( + const sigset_t \*set, + siginfo_t \*info + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EINTR* + Signal interrupted this function. + +**DESCRIPTION:** + +This function selects a pending signal based on the set specified in``set``, atomically clears it from the set of pending signals, and +returns information about that signal in ``info``. + +The prototype of the ``siginfo_t`` structure is the following: +.. code:: c + + typedef struct + { + int si_signo; /* Signal number \*/ + int si_code; /* Cause of the signal \*/ + pid_t si_pid; /* Sending process ID \*/ + uid_t si_uid; /* Real user ID of sending process \*/ + void* si_addr; /* Address of faulting instruction \*/ + int si_status; /* Exit value or signal \*/ + union sigval + { + int sival_int; /* Integer signal value \*/ + void* sival_ptr; /* Pointer signal value \*/ + } si_value; /* Signal value \*/ + } + +sigtimedwait - Synchronously Accept a Signal with Timeout +--------------------------------------------------------- +.. index:: sigtimedwait +.. index:: synchronously accept a signal with timeout + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigtimedwait( + const sigset_t \*set, + siginfo_t \*info, + const struct timespec \*timeout + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EAGAIN* + Timed out while waiting for the specified signal set. + +*EINVAL* + Nanoseconds field of the timeout argument is invalid. + +*EINTR* + Signal interrupted this function. + +**DESCRIPTION:** + +This function selects a pending signal based on the set specified in``set``, atomically clears it from the set of pending signals, and +returns information about that signal in ``info``. The calling thread +will block up to ``timeout`` waiting for the signal to arrive. + +The ``timespec`` structure is defined as follows: +.. code:: c + + struct timespec + { + time_t tv_sec; /* Seconds \*/ + long tv_nsec; /* Nanoseconds \*/ + } + +**NOTES:** + +If ``timeout`` is NULL, then the calling thread will wait forever for +the specified signal set. + +sigqueue - Queue a Signal to a Process +-------------------------------------- +.. index:: sigqueue +.. index:: queue a signal to a process + +**CALLING SEQUENCE:** + +.. code:: c + + #include <signal.h> + int sigqueue( + pid_t pid, + int signo, + const union sigval value + ); + +**STATUS CODES:** + +The function returns 0 on success, otherwise it returns -1 and sets``errno`` to indicate the error. ``errno`` may be set to: + +*EAGAIN* + No resources available to queue the signal. The process has already + queued SIGQUEUE_MAX signals that are still pending at the receiver + or the systemwide resource limit has been exceeded. + +*EINVAL* + The value of the signo argument is an invalid or unsupported signal + number. + +*EPERM* + The process does not have the appropriate privilege to send the signal + to the receiving process. + +*ESRCH* + The process pid does not exist. + +**DESCRIPTION:** + +This function sends the signal specified by ``signo`` to the +process ``pid`` + +The ``sigval`` union is specified as: +.. code:: c + + union sigval + { + int sival_int; /* Integer signal value \*/ + void* sival_ptr; /* Pointer signal value \*/ + } + +**NOTES:** + +Since RTEMS is a single-process system, a signal can only be sent to the calling +process (i.e. the current node). + +alarm - Schedule Alarm +---------------------- +.. index:: alarm +.. index:: schedule alarm + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + unsigned int alarm( + unsigned int seconds + ); + +**STATUS CODES:** + +This call always succeeds. + +If there was a previous ``alarm()`` request with time remaining, +then this routine returns the number of seconds until that outstanding +alarm would have fired. If no previous ``alarm()`` request was +outstanding, then zero is returned. + +**DESCRIPTION:** + +The ``alarm()`` service causes the ``SIGALRM`` signal to +be generated after the number of seconds specified by``seconds`` has elapsed. + +**NOTES:** + +Alarm requests do not queue. If ``alarm`` is called while +a previous request is outstanding, the call will result in +rescheduling the time at which the ``SIGALRM`` signal +will be generated. + +If the notification signal, ``SIGALRM``, is not caught or ignored, the +calling process is terminated. + +ualarm - Schedule Alarm in Microseconds +--------------------------------------- +.. index:: alarm +.. index:: microseonds alarm +.. index:: usecs alarm +.. index:: schedule alarm in microseonds + +**CALLING SEQUENCE:** + +.. code:: c + + #include <unistd.h> + useconds_t ualarm( + useconds_t useconds, + useconds_t interval + ); + +**STATUS CODES:** + +This call always succeeds. + +If there was a previous ``ualarm()`` request with time remaining, +then this routine returns the number of seconds until that outstanding +alarm would have fired. If no previous ``alarm()`` request was +outstanding, then zero is returned. + +**DESCRIPTION:** + +The ``ualarm()`` service causes the ``SIGALRM`` signal to +be generated after the number of microseconds specified by``useconds`` has elapsed. + +When ``interval`` is non-zero, repeated timeout notification occurs +with a period in microseconds specified by ``interval``. + +**NOTES:** + +Alarm requests do not queue. If ``alarm`` is called while +a previous request is outstanding, the call will result in +rescheduling the time at which the ``SIGALRM`` signal +will be generated. + +If the notification signal, ``SIGALRM``, is not caught or ignored, the +calling process is terminated. + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/status_of_implementation.rst b/posix_users/status_of_implementation.rst new file mode 100644 index 0000000..7f535f0 --- /dev/null +++ b/posix_users/status_of_implementation.rst @@ -0,0 +1,43 @@ +Status of Implementation +######################## + +This chapter provides an overview of the status of the implementation +of the POSIX API for RTEMS. The *POSIX 1003.1b Compliance Guide* +provides more detailed information regarding the implementation of +each of the numerous functions, constants, and macros specified by +the POSIX 1003.1b standard. + +RTEMS supports many of the process and user/group oriented services +in a "single user/single process" manner. This means that although +these services may be of limited usefulness or functionality, they +are provided and do work in a coherent manner. This is significant +when porting existing code from UNIX to RTEMS. + +- Implementation + - The current implementation of ``dup()`` is insufficient. + - FIFOs ``mkfifo()`` are not currently implemented. + - Asynchronous IO is not implemented. + - The ``flockfile()`` family is not implemented + - getc/putc unlocked family is not implemented + - Shared Memory is not implemented + - Mapped Memory is not implemented + + - NOTES: + + - For Shared Memory and Mapped Memory services, it is unclear what + level of support is appropriate and possible for RTEMS. + +- Functional Testing + - Tests for unimplemented services + +- Performance Testing + - There are no POSIX Performance Tests. + +- Documentation + + - Many of the service description pages are not complete in this + manual. These need to be completed and information added to the + background and operations sections. + + - Example programs (not just tests) would be very nice. + diff --git a/posix_users/system_database.rst b/posix_users/system_database.rst new file mode 100644 index 0000000..56505a5 --- /dev/null +++ b/posix_users/system_database.rst @@ -0,0 +1,219 @@ +System Databases Manager +######################## + +Introduction +============ + +The +system databases manager is ... + +The directives provided by the system databases manager are: + +- ``getgrgid`` - Get Group File Entry for ID + +- ``getgrgid_r`` - Reentrant Get Group File Entry + +- ``getgrnam`` - Get Group File Entry for Name + +- ``getgrnam_r`` - Reentrant Get Group File Entry for Name + +- ``getpwuid`` - Get Password File Entry for UID + +- ``getpwuid_r`` - Reentrant Get Password File Entry for UID + +- ``getpwnam`` - Get Password File Entry for Name + +- ``getpwnam_r`` - Reentrant Get Password File Entry for Name + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the system databases manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +getgrgid - Get Group File Entry for ID +-------------------------------------- +.. index:: getgrgid +.. index:: get group file entry for id + +**CALLING SEQUENCE:** + +.. code:: c + + int getgrgid( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getgrgid_r - Reentrant Get Group File Entry +------------------------------------------- +.. index:: getgrgid_r +.. index:: reentrant get group file entry + +**CALLING SEQUENCE:** + +.. code:: c + + int getgrgid_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getgrnam - Get Group File Entry for Name +---------------------------------------- +.. index:: getgrnam +.. index:: get group file entry for name + +**CALLING SEQUENCE:** + +.. code:: c + + int getgrnam( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getgrnam_r - Reentrant Get Group File Entry for Name +---------------------------------------------------- +.. index:: getgrnam_r +.. index:: reentrant get group file entry for name + +**CALLING SEQUENCE:** + +.. code:: c + + int getgrnam_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getpwuid - Get Password File Entry for UID +------------------------------------------ +.. index:: getpwuid +.. index:: get password file entry for uid + +**CALLING SEQUENCE:** + +.. code:: c + + int getpwuid( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getpwuid_r - Reentrant Get Password File Entry for UID +------------------------------------------------------ +.. index:: getpwuid_r +.. index:: reentrant get password file entry for uid + +**CALLING SEQUENCE:** + +.. code:: c + + int getpwuid_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getpwnam - Password File Entry for Name +--------------------------------------- +.. index:: getpwnam +.. index:: password file entry for name + +**CALLING SEQUENCE:** + +.. code:: c + + int getpwnam( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +getpwnam_r - Reentrant Get Password File Entry for Name +------------------------------------------------------- +.. index:: getpwnam_r +.. index:: reentrant get password file entry for name + +**CALLING SEQUENCE:** + +.. code:: c + + int getpwnam_r( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: COPYRIGHT(c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation(OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/thread.rst b/posix_users/thread.rst new file mode 100644 index 0000000..4bd80ed --- /dev/null +++ b/posix_users/thread.rst @@ -0,0 +1,1333 @@ +Thread Manager +############## + +Introduction +============ + +The thread manager implements the functionality required of the thread +manager as defined by POSIX 1003.1b. This standard requires that +a compliant operating system provide the facilties to manage multiple +threads of control and defines the API that must be provided. + +The services provided by the thread manager are: + +- ``pthread_attr_init`` - Initialize a Thread Attribute Set + +- ``pthread_attr_destroy`` - Destroy a Thread Attribute Set + +- ``pthread_attr_setdetachstate`` - Set Detach State + +- ``pthread_attr_getdetachstate`` - Get Detach State + +- ``pthread_attr_setstacksize`` - Set Thread Stack Size + +- ``pthread_attr_getstacksize`` - Get Thread Stack Size + +- ``pthread_attr_setstackaddr`` - Set Thread Stack Address + +- ``pthread_attr_getstackaddr`` - Get Thread Stack Address + +- ``pthread_attr_setscope`` - Set Thread Scheduling Scope + +- ``pthread_attr_getscope`` - Get Thread Scheduling Scope + +- ``pthread_attr_setinheritsched`` - Set Inherit Scheduler Flag + +- ``pthread_attr_getinheritsched`` - Get Inherit Scheduler Flag + +- ``pthread_attr_setschedpolicy`` - Set Scheduling Policy + +- ``pthread_attr_getschedpolicy`` - Get Scheduling Policy + +- ``pthread_attr_setschedparam`` - Set Scheduling Parameters + +- ``pthread_attr_getschedparam`` - Get Scheduling Parameters + +- ``pthread_attr_getaffinity_np`` - Get Thread Affinity Attribute + +- ``pthread_attr_setaffinity_np`` - Set Thread Affinity Attribute + +- ``pthread_create`` - Create a Thread + +- ``pthread_exit`` - Terminate the Current Thread + +- ``pthread_detach`` - Detach a Thread + +- ``pthread_getattr_np`` - Get Thread Attributes + +- ``pthread_join`` - Wait for Thread Termination + +- ``pthread_self`` - Get Thread ID + +- ``pthread_equal`` - Compare Thread IDs + +- ``pthread_once`` - Dynamic Package Initialization + +- ``pthread_setschedparam`` - Set Thread Scheduling Parameters + +- ``pthread_getschedparam`` - Get Thread Scheduling Parameters + +- ``pthread_getaffinity_np`` - Get Thread Affinity + +- ``pthread_setaffinity_np`` - Set Thread Affinity + +Background +========== + +Thread Attributes +----------------- + +Thread attributes are utilized only at thread creation time. A thread +attribute structure may be initialized and passed as an argument to +the ``pthread_create`` routine. + +*stack address* + is the address of the optionally user specified stack area for this thread. + If this value is NULL, then RTEMS allocates the memory for the thread stack + from the RTEMS Workspace Area. Otherwise, this is the user specified + address for the memory to be used for the thread’s stack. Each thread must + have a distinct stack area. Each processor family has different alignment + rules which should be followed. + +*stack size* + is the minimum desired size for this thread’s stack area. + If the size of this area as specified by the stack size attribute + is smaller than the minimum for this processor family and the stack + is not user specified, then RTEMS will automatically allocate a + stack of the minimum size for this processor family. + +*contention scope* + specifies the scheduling contention scope. RTEMS only supports the + PTHREAD_SCOPE_PROCESS scheduling contention scope. + +*scheduling inheritance* + specifies whether a user specified or the scheduling policy and + parameters of the currently executing thread are to be used. When + this is PTHREAD_INHERIT_SCHED, then the scheduling policy and + parameters of the currently executing thread are inherited by + the newly created thread. + +*scheduling policy and parameters* + specify the manner in which the thread will contend for the processor. + The scheduling parameters are interpreted based on the specified policy. + All policies utilize the thread priority parameter. + +Operations +========== + +There is currently no text in this section. + +Services +======== + +This section details the thread manager’s services. +A subsection is dedicated to each of this manager’s services +and describes the calling sequence, related constants, usage, +and status codes. + +pthread_attr_init - Initialize a Thread Attribute Set +----------------------------------------------------- +.. index:: pthread_attr_init +.. index:: initialize a thread attribute set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_init( + pthread_attr_t \*attr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_init`` routine initializes the thread attributes +object specified by ``attr`` with the default value for all of the +individual attributes. + +**NOTES:** + +The settings in the default attributes are implementation defined. For +RTEMS, the default attributes are as follows: + +- stackadr + is not set to indicate that RTEMS is to allocate the stack memory. + +- stacksize + is set to ``PTHREAD_MINIMUM_STACK_SIZE``. + +- contentionscope + is set to ``PTHREAD_SCOPE_PROCESS``. + +- inheritsched + is set to ``PTHREAD_INHERIT_SCHED`` to indicate that the created + thread inherits its scheduling attributes from its parent. + +- detachstate + is set to ``PTHREAD_CREATE_JOINABLE``. + +pthread_attr_destroy - Destroy a Thread Attribute Set +----------------------------------------------------- +.. index:: pthread_attr_destroy +.. index:: destroy a thread attribute set + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_destroy( + pthread_attr_t \*attr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +**DESCRIPTION:** + +The ``pthread_attr_destroy`` routine is used to destroy a thread +attributes object. The behavior of using an attributes object after +it is destroyed is implementation dependent. + +**NOTES:** + +NONE + +pthread_attr_setdetachstate - Set Detach State +---------------------------------------------- +.. index:: pthread_attr_setdetachstate +.. index:: set detach state + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_setdetachstate( + pthread_attr_t \*attr, + int detachstate + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The detachstate argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_setdetachstate`` routine is used to value of the``detachstate`` attribute. This attribute controls whether the +thread is created in a detached state. + +The ``detachstate`` can be either ``PTHREAD_CREATE_DETACHED`` or``PTHREAD_CREATE_JOINABLE``. The default value for all threads is``PTHREAD_CREATE_JOINABLE``. + +**NOTES:** + +If a thread is in a detached state, +then the use of the ID with the ``pthread_detach`` or``pthread_join`` routines is an error. + +pthread_attr_getdetachstate - Get Detach State +---------------------------------------------- +.. index:: pthread_attr_getdetachstate +.. index:: get detach state + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_getdetachstate( + const pthread_attr_t \*attr, + int \*detachstate + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The detatchstate pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_getdetachstate`` routine is used to obtain the +current value of the ``detachstate`` attribute as specified +by the ``attr`` thread attribute object. + +**NOTES:** + +NONE + +pthread_attr_setstacksize - Set Thread Stack Size +------------------------------------------------- +.. index:: pthread_attr_setstacksize +.. index:: set thread stack size + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_setstacksize( + pthread_attr_t \*attr, + size_t stacksize + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +**DESCRIPTION:** + +The ``pthread_attr_setstacksize`` routine is used to set the``stacksize`` attribute in the ``attr`` thread attribute +object. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_ATTR_STACKSIZE`` to indicate that this +routine is supported. + +If the specified stacksize is below the minimum required for this CPU +(``PTHREAD_STACK_MIN``, then the stacksize will be set to the minimum +for this CPU. + +pthread_attr_getstacksize - Get Thread Stack Size +------------------------------------------------- +.. index:: pthread_attr_getstacksize +.. index:: get thread stack size + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_getstacksize( + const pthread_attr_t \*attr, + size_t \*stacksize + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The stacksize pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_getstacksize`` routine is used to obtain the``stacksize`` attribute in the ``attr`` thread attribute +object. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_ATTR_STACKSIZE`` to indicate that this +routine is supported. + +pthread_attr_setstackaddr - Set Thread Stack Address +---------------------------------------------------- +.. index:: pthread_attr_setstackaddr +.. index:: set thread stack address + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_setstackaddr( + pthread_attr_t \*attr, + void \*stackaddr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +**DESCRIPTION:** + +The ``pthread_attr_setstackaddr`` routine is used to set the``stackaddr`` attribute in the ``attr`` thread attribute +object. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_ATTR_STACKADDR`` to indicate that this +routine is supported. + +It is imperative to the proper operation of the system that +each thread have sufficient stack space. + +pthread_attr_getstackaddr - Get Thread Stack Address +---------------------------------------------------- +.. index:: pthread_attr_getstackaddr +.. index:: get thread stack address + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_getstackaddr( + const pthread_attr_t \*attr, + void \**stackaddr + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The stackaddr pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_getstackaddr`` routine is used to obtain the``stackaddr`` attribute in the ``attr`` thread attribute +object. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_ATTR_STACKADDR`` to indicate that this +routine is supported. + +pthread_attr_setscope - Set Thread Scheduling Scope +--------------------------------------------------- +.. index:: pthread_attr_setscope +.. index:: set thread scheduling scope + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_setscope( + pthread_attr_t \*attr, + int contentionscope + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The contention scope specified is not valid. + +*ENOTSUP* + The contention scope specified (PTHREAD_SCOPE_SYSTEM) is not supported. + +**DESCRIPTION:** + +The ``pthread_attr_setscope`` routine is used to set the contention +scope field in the thread attribute object ``attr`` to the value +specified by ``contentionscope``. + +The ``contentionscope`` must be either ``PTHREAD_SCOPE_SYSTEM`` +to indicate that the thread is to be within system scheduling contention +or ``PTHREAD_SCOPE_PROCESS`` indicating that the thread is to be +within the process scheduling contention scope. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_getscope - Get Thread Scheduling Scope +--------------------------------------------------- +.. index:: pthread_attr_getscope +.. index:: get thread scheduling scope + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_getscope( + const pthread_attr_t \*attr, + int \*contentionscope + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The contentionscope pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_getscope`` routine is used to obtain the +value of the contention scope field in the thread attributes +object ``attr``. The current value is returned in``contentionscope``. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_setinheritsched - Set Inherit Scheduler Flag +--------------------------------------------------------- +.. index:: pthread_attr_setinheritsched +.. index:: set inherit scheduler flag + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_setinheritsched( + pthread_attr_t \*attr, + int inheritsched + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The specified scheduler inheritance argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_setinheritsched`` routine is used to set the +inherit scheduler field in the thread attribute object ``attr`` to +the value specified by ``inheritsched``. + +The ``contentionscope`` must be either ``PTHREAD_INHERIT_SCHED`` +to indicate that the thread is to inherit the scheduling policy +and parameters fromthe creating thread, or ``PTHREAD_EXPLICIT_SCHED`` +to indicate that the scheduling policy and parameters for this thread +are to be set from the corresponding values in the attributes object. +If ``contentionscope`` is ``PTHREAD_INHERIT_SCHED``, then the +scheduling attributes in the ``attr`` structure will be ignored +at thread creation time. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_getinheritsched - Get Inherit Scheduler Flag +--------------------------------------------------------- +.. index:: pthread_attr_getinheritsched +.. index:: get inherit scheduler flag + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_getinheritsched( + const pthread_attr_t \*attr, + int \*inheritsched + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The inheritsched pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_getinheritsched`` routine is used to +object the current value of the inherit scheduler field in +the thread attribute object ``attr``. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_setschedpolicy - Set Scheduling Policy +--------------------------------------------------- +.. index:: pthread_attr_setschedpolicy +.. index:: set scheduling policy + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_setschedpolicy( + pthread_attr_t \*attr, + int policy + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*ENOTSUP* + The specified scheduler policy argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_setschedpolicy`` routine is used to set the +scheduler policy field in the thread attribute object ``attr`` to +the value specified by ``policy``. + +Scheduling policies may be one of the following: + +- ``SCHED_DEFAULT`` + +- ``SCHED_FIFO`` + +- ``SCHED_RR`` + +- ``SCHED_SPORADIC`` + +- ``SCHED_OTHER`` + +The precise meaning of each of these is discussed elsewhere in this +manual. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_getschedpolicy - Get Scheduling Policy +--------------------------------------------------- +.. index:: pthread_attr_getschedpolicy +.. index:: get scheduling policy + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_getschedpolicy( + const pthread_attr_t \*attr, + int \*policy + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The specified scheduler policy argument pointer is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_getschedpolicy`` routine is used to obtain the +scheduler policy field from the thread attribute object ``attr``. +The value of this field is returned in ``policy``. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_setschedparam - Set Scheduling Parameters +------------------------------------------------------ +.. index:: pthread_attr_setschedparam +.. index:: set scheduling parameters + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_setschedparam( + pthread_attr_t \*attr, + const struct sched_param param + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The specified scheduler parameter argument is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_setschedparam`` routine is used to set the +scheduler parameters field in the thread attribute object ``attr`` to +the value specified by ``param``. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_getschedparam - Get Scheduling Parameters +------------------------------------------------------ +.. index:: pthread_attr_getschedparam +.. index:: get scheduling parameters + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_attr_getschedparam( + const pthread_attr_t \*attr, + struct sched_param \*param + ); + +**STATUS CODES:** + +*EINVAL* + The attribute pointer argument is invalid. + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The specified scheduler parameter argument pointer is invalid. + +**DESCRIPTION:** + +The ``pthread_attr_getschedparam`` routine is used to obtain the +scheduler parameters field from the thread attribute object ``attr``. +The value of this field is returned in ``param``. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_attr_getaffinity_np - Get Thread Affinity Attribute +----------------------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #define _GNU_SOURCE + #include <pthread.h> + int pthread_attr_getaffinity_np( + const pthread_attr_t \*attr, + size_t cpusetsize, + cpu_set_t \*cpuset + ); + +**STATUS CODES:** + +*EFAULT* + The attribute pointer argument is invalid. + +*EFAULT* + The cpuset pointer argument is invalid. + +*EINVAL* + The ``cpusetsize`` does not match the value of ``affinitysetsize`` + field in the thread attribute object. + +**DESCRIPTION:** + +The ``pthread_attr_getaffinity_np`` routine is used to obtain the``affinityset`` field from the thread attribute object ``attr``. +The value of this field is returned in ``cpuset``. + +**NOTES:** + +NONE + +pthread_attr_setaffinity_np - Set Thread Affinity Attribute +----------------------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #define _GNU_SOURCE + #include <pthread.h> + int pthread_attr_setaffinity_np( + pthread_attr_t \*attr, + size_t cpusetsize, + const cpu_set_t \*cpuset + ); + +**STATUS CODES:** + +*EFAULT* + The attribute pointer argument is invalid. + +*EFAULT* + The cpuset pointer argument is invalid. + +*EINVAL* + The ``cpusetsize`` does not match the value of ``affinitysetsize`` + field in the thread attribute object. + +*EINVAL* + The ``cpuset`` did not select a valid cpu. + +*EINVAL* + The ``cpuset`` selected a cpu that was invalid. + +**DESCRIPTION:** + +The ``pthread_attr_setaffinity_np`` routine is used to set the``affinityset`` field in the thread attribute object ``attr``. +The value of this field is returned in ``cpuset``. + +**NOTES:** + +NONE + +pthread_create - Create a Thread +-------------------------------- +.. index:: pthread_create +.. index:: create a thread + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_create( + pthread_t \*thread, + const pthread_attr_t \*attr, + void (\*start_routine)( void \*), + void \*arg + ); + +**STATUS CODES:** + +*EINVAL* + The attribute set is not initialized. + +*EINVAL* + The user specified a stack address and the size of the area was not + large enough to meet this processor’s minimum stack requirements. + +*EINVAL* + The specified scheduler inheritance policy was invalid. + +*ENOTSUP* + The specified contention scope was PTHREAD_SCOPE_PROCESS. + +*EINVAL* + The specified thread priority was invalid. + +*EINVAL* + The specified scheduling policy was invalid. + +*EINVAL* + The scheduling policy was SCHED_SPORADIC and the specified replenishment + period is less than the initial budget. + +*EINVAL* + The scheduling policy was SCHED_SPORADIC and the specified low priority + is invalid. + +*EAGAIN* + The system lacked the necessary resources to create another thread, or the + self imposed limit on the total number of threads in a process + PTHREAD_THREAD_MAX would be exceeded. + +*EINVAL* + Invalid argument passed. + +**DESCRIPTION:** + +The ``pthread_create`` routine is used to create a new thread with +the attributes specified by ``attr``. If the ``attr`` argument +is ``NULL``, then the default attribute set will be used. Modification +of the contents of ``attr`` after this thread is created does not +have an impact on this thread. + +The thread begins execution at the address specified by ``start_routine`` +with ``arg`` as its only argument. If ``start_routine`` returns, +then it is functionally equivalent to the thread executing the``pthread_exit`` service. + +Upon successful completion, the ID of the created thread is returned in the``thread`` argument. + +**NOTES:** + +There is no concept of a single main thread in RTEMS as there is in +a tradition UNIX system. POSIX requires that the implicit return of +the main thread results in the same effects as if there were a call +to ``exit``. This does not occur in RTEMS. + +The signal mask of the newly created thread is inherited from its +creator and the set of pending signals for this thread is empty. + +pthread_exit - Terminate the Current Thread +------------------------------------------- +.. index:: pthread_exit +.. index:: terminate the current thread + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + void pthread_exit( + void \*status + ); + +**STATUS CODES:** + +*NONE* + +**DESCRIPTION:** + +The ``pthread_exit`` routine is used to terminate the calling thread. +The ``status`` is made available to any successful join with the +terminating thread. + +When a thread returns from its start routine, it results in an +implicit call to the ``pthread_exit`` routine with the return +value of the function serving as the argument to ``pthread_exit``. + +**NOTES:** + +Any cancellation cleanup handlers that hace been pushed and not yet popped +shall be popped in reverse of the order that they were pushed. After +all cancellation cleanup handlers have been executed, if the +thread has any thread-specific data, destructors for that data will +be invoked. + +Thread termination does not release or free any application visible +resources including byt not limited to mutexes, file descriptors, allocated +memory, etc.. Similarly, exitting a thread does not result in any +process-oriented cleanup activity. + +There is no concept of a single main thread in RTEMS as there is in +a tradition UNIX system. POSIX requires that the implicit return of +the main thread results in the same effects as if there were a call +to ``exit``. This does not occur in RTEMS. + +All access to any automatic variables allocated by the threads is lost +when the thread exits. Thus references (i.e. pointers) to local variables +of a thread should not be used in a global manner without care. As +a specific example, a pointer to a local variable should NOT be used +as the return value. + +pthread_detach - Detach a Thread +-------------------------------- +.. index:: pthread_detach +.. index:: detach a thread + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_detach( + pthread_t thread + ); + +**STATUS CODES:** + +*ESRCH* + The thread specified is invalid. + +*EINVAL* + The thread specified is not a joinable thread. + +**DESCRIPTION:** + +The ``pthread_detach`` routine is used to to indicate that storage +for ``thread`` can be reclaimed when the thread terminates without +another thread joinging with it. + +**NOTES:** + +If any threads have previously joined with the specified thread, then they +will remain joined with that thread. Any subsequent calls to``pthread_join`` on the specified thread will fail. + +.. COMMENT: pthread_getattr_np + +pthread_getattr_np - Get Thread Attributes +------------------------------------------ +.. index:: pthread_getattr_np +.. index:: get thread attributes + +**CALLING SEQUENCE:** + +.. code:: c + + #define _GNU_SOURCE + #include <pthread.h> + int pthread_getattr_np( + pthread_t thread, + pthread_attr_t \*attr + ); + +**STATUS CODES:** + +*ESRCH* + The thread specified is invalid. + +*EINVAL* + The attribute pointer argument is invalid. + +**DESCRIPTION:** + +The ``pthread_getattr_np`` routine is used to obtain the +attributes associated with ``thread``. + +**NOTES:** + +Modification of the execution modes and priority through the Classic API +may result in a combination that is not representable in the POSIX API. + +pthread_join - Wait for Thread Termination +------------------------------------------ +.. index:: pthread_join +.. index:: wait for thread termination + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_join( + pthread_t thread, + void \**value_ptr + ); + +**STATUS CODES:** + +*ESRCH* + The thread specified is invalid. + +*EINVAL* + The thread specified is not a joinable thread. + +*EDEADLK* + A deadlock was detected or thread is the calling thread. + +**DESCRIPTION:** + +The ``pthread_join`` routine suspends execution of the calling thread +until ``thread`` terminates. If ``thread`` has already terminated, +then this routine returns immediately. The value returned by ``thread`` +(i.e. passed to ``pthread_exit`` is returned in ``value_ptr``. + +When this routine returns, then ``thread`` has been terminated. + +**NOTES:** + +The results of multiple simultaneous joins on the same thread is undefined. + +If any threads have previously joined with the specified thread, then they +will remain joined with that thread. Any subsequent calls to``pthread_join`` on the specified thread will fail. + +If value_ptr is NULL, then no value is returned. + +pthread_self - Get Thread ID +---------------------------- +.. index:: pthread_self +.. index:: get thread id + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + pthread_t pthread_self( void ); + +**STATUS CODES:** + +The value returned is the ID of the calling thread. + +**DESCRIPTION:** + +This routine returns the ID of the calling thread. + +**NOTES:** + +NONE + +pthread_equal - Compare Thread IDs +---------------------------------- +.. index:: pthread_equal +.. index:: compare thread ids + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_equal( + pthread_t t1, + pthread_t t2 + ); + +**STATUS CODES:** + +*zero* + The thread ids are not equal. + +*non-zero* + The thread ids are equal. + +**DESCRIPTION:** + +The ``pthread_equal`` routine is used to compare two thread +IDs and determine if they are equal. + +**NOTES:** + +The behavior is undefined if the thread IDs are not valid. + +pthread_once - Dynamic Package Initialization +--------------------------------------------- +.. index:: pthread_once +.. index:: dynamic package initialization + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + pthread_once_t once_control = PTHREAD_ONCE_INIT; + int pthread_once( + pthread_once_t \*once_control, + void (\*init_routine)(void) + ); + +**STATUS CODES:** + +NONE + +**DESCRIPTION:** + +The ``pthread_once`` routine is used to provide controlled initialization +of variables. The first call to ``pthread_once`` by any thread with the +same ``once_control`` will result in the ``init_routine`` being +invoked with no arguments. Subsequent calls to ``pthread_once`` with +the same ``once_control`` will have no effect. + +The ``init_routine`` is guaranteed to have run to completion when +this routine returns to the caller. + +**NOTES:** + +The behavior of ``pthread_once`` is undefined if ``once_control`` +is automatic storage (i.e. on a task stack) or is not initialized using``PTHREAD_ONCE_INIT``. + +pthread_setschedparam - Set Thread Scheduling Parameters +-------------------------------------------------------- +.. index:: pthread_setschedparam +.. index:: set thread scheduling parameters + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_setschedparam( + pthread_t thread, + int policy, + struct sched_param \*param + ); + +**STATUS CODES:** + +*EINVAL* + The scheduling parameters indicated by the parameter param is invalid. + +*EINVAL* + The value specified by policy is invalid. + +*EINVAL* + The scheduling policy was SCHED_SPORADIC and the specified replenishment + period is less than the initial budget. + +*EINVAL* + The scheduling policy was SCHED_SPORADIC and the specified low priority + is invalid. + +*ESRCH* + The thread indicated was invalid. + +**DESCRIPTION:** + +The ``pthread_setschedparam`` routine is used to set the +scheduler parameters currently associated with the thread specified +by ``thread`` to the policy specified by ``policy``. The +contents of ``param`` are interpreted based upon the ``policy`` +argument. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +pthread_getschedparam - Get Thread Scheduling Parameters +-------------------------------------------------------- +.. index:: pthread_getschedparam +.. index:: get thread scheduling parameters + +**CALLING SEQUENCE:** + +.. code:: c + + #include <pthread.h> + int pthread_getschedparam( + pthread_t thread, + int \*policy, + struct sched_param \*param + ); + +**STATUS CODES:** + +*EINVAL* + The policy pointer argument is invalid. + +*EINVAL* + The scheduling parameters pointer argument is invalid. + +*ESRCH* + The thread indicated by the parameter thread is invalid. + +**DESCRIPTION:** + +The ``pthread_getschedparam`` routine is used to obtain the +scheduler policy and parameters associated with ``thread``. +The current policy and associated parameters values returned in``policy`` and ``param``, respectively. + +**NOTES:** + +As required by POSIX, RTEMS defines the feature symbol``_POSIX_THREAD_PRIORITY_SCHEDULING`` to indicate that the +family of routines to which this routine belongs is supported. + +.. COMMENT: pthread_getaffinity_np + +pthread_getaffinity_np - Get Thread Affinity +-------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #define _GNU_SOURCE + #include <pthread.h> + int pthread_getaffinity_np( + const pthread_t id, + size_t cpusetsize, + cpu_set_t \*cpuset + ); + +**STATUS CODES:** + +*EFAULT* + The cpuset pointer argument is invalid. + +*EINVAL* + The ``cpusetsize`` does not match the value of ``affinitysetsize`` + field in the thread attribute object. + +**DESCRIPTION:** + +The ``pthread_getaffinity_np`` routine is used to obtain the``affinity.set`` field from the thread control object associated +with the ``id``. The value of this field is returned in ``cpuset``. + +**NOTES:** + +NONE + +.. COMMENT: pthread_setaffinity_np + +pthread_setaffinity_np - Set Thread Affinity +-------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #define _GNU_SOURCE + #include <pthread.h> + int pthread_setaffinity_np( + pthread_t id, + size_t cpusetsize, + const cpu_set_t \*cpuset + ); + +**STATUS CODES:** + +*EFAULT* + The cpuset pointer argument is invalid. + +*EINVAL* + The ``cpusetsize`` does not match the value of ``affinitysetsize`` + field in the thread attribute object. + +*EINVAL* + The ``cpuset`` did not select a valid cpu. + +*EINVAL* + The ``cpuset`` selected a cpu that was invalid. + +**DESCRIPTION:** + +The ``pthread_setaffinity_np`` routine is used to set the``affinityset`` field of the thread object ``id``. +The value of this field is returned in ``cpuset`` + +**NOTES:** + +NONE + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/thread_cancellation.rst b/posix_users/thread_cancellation.rst new file mode 100644 index 0000000..5c8aac3 --- /dev/null +++ b/posix_users/thread_cancellation.rst @@ -0,0 +1,173 @@ +Thread Cancellation Manager +########################### + +Introduction +============ + +The +thread cancellation manager is ... + +The directives provided by the thread cancellation manager are: + +- ``pthread_cancel`` - Cancel Execution of a Thread + +- ``pthread_setcancelstate`` - Set Cancelability State + +- ``pthread_setcanceltype`` - Set Cancelability Type + +- ``pthread_testcancel`` - Create Cancellation Point + +- ``pthread_cleanup_push`` - Establish Cancellation Handler + +- ``pthread_cleanup_pop`` - Remove Cancellation Handler + +Background +========== + +There is currently no text in this section. + +Operations +========== + +There is currently no text in this section. + +Directives +========== + +This section details the thread cancellation manager’s directives. +A subsection is dedicated to each of this manager’s directives +and describes the calling sequence, related constants, usage, +and status codes. + +pthread_cancel - Cancel Execution of a Thread +--------------------------------------------- +.. index:: pthread_cancel +.. index:: cancel execution of a thread + +**CALLING SEQUENCE:** + +.. code:: c + + int pthread_cancel( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +pthread_setcancelstate - Set Cancelability State +------------------------------------------------ +.. index:: pthread_setcancelstate +.. index:: set cancelability state + +**CALLING SEQUENCE:** + +.. code:: c + + int pthread_setcancelstate( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +pthread_setcanceltype - Set Cancelability Type +---------------------------------------------- +.. index:: pthread_setcanceltype +.. index:: set cancelability type + +**CALLING SEQUENCE:** + +.. code:: c + + int pthread_setcanceltype( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +pthread_testcancel - Create Cancellation Point +---------------------------------------------- +.. index:: pthread_testcancel +.. index:: create cancellation point + +**CALLING SEQUENCE:** + +.. code:: c + + int pthread_testcancel( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +pthread_cleanup_push - Establish Cancellation Handler +----------------------------------------------------- +.. index:: pthread_cleanup_push +.. index:: establish cancellation handler + +**CALLING SEQUENCE:** + +.. code:: c + + int pthread_cleanup_push( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +pthread_cleanup_pop - Remove Cancellation Handler +------------------------------------------------- +.. index:: pthread_cleanup_pop +.. index:: remove cancellation handler + +**CALLING SEQUENCE:** + +.. code:: c + + int pthread_cleanup_push( + ); + +**STATUS CODES:** + +*E* + The + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: COPYRIGHT (c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation (OAR). + +.. COMMENT: All rights reserved. + diff --git a/posix_users/timer.rst b/posix_users/timer.rst new file mode 100644 index 0000000..4adf320 --- /dev/null +++ b/posix_users/timer.rst @@ -0,0 +1,157 @@ +Timer Manager +############# + +Introduction +============ + +The timer manager is ... + +The services provided by the timer manager are: + +- ``timer_create`` - Create a Per-Process Timer + +- ``timer_delete`` - Delete a Per-Process Timer + +- ``timer_settime`` - Set Next Timer Expiration + +- ``timer_gettime`` - Get Time Remaining on Timer + +- ``timer_getoverrun`` - Get Timer Overrun Count + +Background +========== + +Operations +========== + +System Calls +============ + +This section details the timer manager’s services. +A subsection is dedicated to each of this manager’s services +and describes the calling sequence, related constants, usage, +and status codes. + +.. COMMENT: timer_create + +timer_create - Create a Per-Process Timer +----------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + #include <signal.h> + int timer_create( + clockid_t clock_id, + struct sigevent \*evp, + timer_t \*timerid + ); + +**STATUS CODES:** + +``EXXX`` - + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: timer_delete + +timer_delete - Delete a Per-Process Timer +----------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int timer_delete( + timer_t timerid + ); + +**STATUS CODES:** + +``EXXX`` - + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: timer_settime + +timer_settime - Set Next Timer Expiration +----------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int timer_settime( + timer_t timerid, + int flags, + const struct itimerspec \*value, + struct itimerspec \*ovalue + ); + +**STATUS CODES:** + +``EXXX`` - + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: timer_gettime + +timer_gettime - Get Time Remaining on Timer +------------------------------------------- + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int timer_gettime( + timer_t timerid, + struct itimerspec \*value + ); + +**STATUS CODES:** + +``EXXX`` - + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: timer_getoverrun + +timer_getoverrun - Get Timer Overrun Count +------------------------------------------ + +**CALLING SEQUENCE:** + +.. code:: c + + #include <time.h> + int timer_getoverrun( + timer_t timerid + ); + +**STATUS CODES:** + +``EXXX`` - + +**DESCRIPTION:** + +**NOTES:** + +.. COMMENT: COPYRIGHT(c) 1988-2002. + +.. COMMENT: On-Line Applications Research Corporation(OAR). + +.. COMMENT: All rights reserved. + |