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diff --git a/posix_users/posix_users_old_reference_only.rst b/posix_users/posix_users_old_reference_only.rst deleted file mode 100644 index 0ac495c..0000000 --- a/posix_users/posix_users_old_reference_only.rst +++ /dev/null @@ -1,11612 +0,0 @@ -.. comment SPDX-License-Identifier: CC-BY-SA-4.0 - -:orphan: - - - -.. COMMENT: %**end of header - -.. COMMENT: COPYRIGHT (c) 1989-2013. - -.. COMMENT: On-Line Applications Research Corporation (OAR). - -.. COMMENT: All rights reserved. - -.. COMMENT: Master file for the POSIX API User's Guide - -.. COMMENT: Joel's Questions - -.. COMMENT: 1. Why does paragraphindent only impact makeinfo? - -.. COMMENT: 2. Why does paragraphindent show up in HTML? - -.. COMMENT: COPYRIGHT (c) 1988-2002. - -.. COMMENT: On-Line Applications Research Corporation (OAR). - -.. COMMENT: All rights reserved. - -.. COMMENT: The following determines which set of the tables and figures we will use. - -.. COMMENT: We default to ASCII but if available TeX or HTML versions will - -.. COMMENT: be used instead. - -.. COMMENT: @clear use-html - -.. COMMENT: @clear use-tex - -.. COMMENT: The following variable says to use texinfo or html for the two column - -.. COMMENT: texinfo tables. For somethings the format does not look good in html. - -.. COMMENT: With our adjustment to the left column in TeX, it nearly always looks - -.. COMMENT: good printed. - -.. COMMENT: Custom whitespace adjustments. We could fiddle a bit more. - -.. COMMENT: variable substitution info: - -.. COMMENT: Note: At the moment we do not document the Ada interface but by building - -.. COMMENT: in the infrastructure Florist support should be simple to add. - -.. COMMENT: the language is @value{LANGUAGE} - -.. COMMENT: NOTE: don't use underscore in the name - -.. COMMENT: Title Page Stuff - -.. COMMENT: I don't really like having a short title page. -joel - -.. COMMENT: @shorttitlepage RTEMS POSIX API User's Guide - -============================ -RTEMS POSIX API User’s Guide -============================ - -.. COMMENT: COPYRIGHT (c) 1988-2015. - -.. COMMENT: On-Line Applications Research Corporation (OAR). - -.. COMMENT: All rights reserved. - -.. COMMENT: The following puts a space somewhere on an otherwise empty page so we - -.. COMMENT: can force the copyright description onto a left hand page. - -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. - -RTEMS POSIX API User’s Guide -############################ - -.. COMMENT: COPYRIGHT (c) 1989-2011. - -.. COMMENT: On-Line Applications Research Corporation (OAR). - -.. COMMENT: All rights reserved. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -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. - -Command and Variable Index -########################## - -.. COMMENT: There are currently no Command and Variable Index entries. - -Concept Index -############# - -.. COMMENT: There are currently no Concept Index entries. - |