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authorJoel Sherrill <joel.sherrill@OARcorp.com>2011-01-10 16:14:07 +0000
committerJoel Sherrill <joel.sherrill@OARcorp.com>2011-01-10 16:14:07 +0000
commite7620cbd10065ee2dacb167bc3c2d0ddb9c5ad3f (patch)
tree2acd8930cd9a81f6e58bdb50cb5b67bc23f6a920
parent174ac5de2ed6a0a85560f514ce96dd61480a2f33 (diff)
downloadrtems-e7620cbd10065ee2dacb167bc3c2d0ddb9c5ad3f.tar.bz2
2011-01-10 Danila Bespalov <danila DOT bespalov AT gmail DOT com>
* posix_users/posix_users.texi, posix_users/signal.t: Review and improve as part of Google Code-In 2010.
-rw-r--r--doc/ChangeLog5
-rw-r--r--doc/posix_users/posix_users.texi10
-rw-r--r--doc/posix_users/signal.t263
3 files changed, 206 insertions, 72 deletions
diff --git a/doc/ChangeLog b/doc/ChangeLog
index ec47a37210..2ce05b74da 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,8 @@
+2011-01-10 Danila Bespalov <danila DOT bespalov AT gmail DOT com>
+
+ * posix_users/posix_users.texi, posix_users/signal.t: Review and
+ improve as part of Google Code-In 2010.
+
2011-01-02 Danila Bespalov <danila DOT bespalov AT gmail DOT com>
* started/buildc.t, started/buildrt.t, started/nt.t, started/require.t,
diff --git a/doc/posix_users/posix_users.texi b/doc/posix_users/posix_users.texi
index 3505105fd9..442b12e6ec 100644
--- a/doc/posix_users/posix_users.texi
+++ b/doc/posix_users/posix_users.texi
@@ -16,7 +16,7 @@
@c
@c
-@c Master file for the C User's Guide
+@c Master file for the POSIX API User's Guide
@c
@c Joel's Questions
@@ -43,7 +43,7 @@
@c in the infrastructure Florist support should be simple to add.
@set is-C
@clear is-Ada
-@set LANGUAGE C
+@set LANGUAGE C
@set STRUCTURE structure
@set ROUTINE function
@set OR |
@@ -63,7 +63,7 @@
@c @shorttitlepage RTEMS POSIX API User's Guide
@setchapternewpage odd
-@settitle RTEMS POSIX API User's Guide
+@settitle RTEMS POSIX API User's Guide
@titlepage
@finalout
@@ -139,8 +139,8 @@ This is the online version of the RTEMS POSIX API User's Guide
@end menu
@end ifinfo
-@c
-@c
+@c
+@c
@c Need to copy the emacs stuff and "trailer stuff" (index, toc) into here
@c
diff --git a/doc/posix_users/signal.t b/doc/posix_users/signal.t
index 933faa56c0..136843c5d7 100644
--- a/doc/posix_users/signal.t
+++ b/doc/posix_users/signal.t
@@ -56,8 +56,9 @@ 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.
+multiple occurrences of that signal are recorded as a
+single occurrence of that signal.
+@c 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
@@ -102,22 +103,22 @@ pending. The first thread to unblock the signal (@code{sigprocmask()} or
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 @code{sigset_t} -- that are used to
-provide arguments to the services that mask, unmask, and
+signal sets -- type @code{sigset_t} -- that are used to
+provide arguments to the services that mask, unmask, and
check on pending signals.
@subsection Blocking Until Signal Generation
A thread may block until receipt of a signal. The "sigwait"
-and "pause" families of services block until the requested
-signal is received or if using @code{sigtimedwait()} until the specified
+and "pause" families of functions block until the requested
+signal is received or if using @code{sigtimedwait()} until the specified
timeout period has elapsed.
@subsection 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
+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 @code{kill()} or at a thread by the service
@code{pthread_kill()}
@@ -150,6 +151,9 @@ int sigaddset(
@subheading STATUS CODES:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
@item EINVAL
Invalid argument passed.
@@ -158,11 +162,12 @@ Invalid argument passed.
@subheading DESCRIPTION:
-This function adds the @code{signo} to the specified signal @code{set}.
+This function adds the signal @code{signo} to the specified signal @code{set}.
@subheading NOTES:
-NONE
+The set must be initialized using either @code{sigemptyset} or @code{sigfillset}
+before using this function.
@c
@c
@@ -186,6 +191,9 @@ int sigdelset(
@subheading STATUS CODES:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
@item EINVAL
Invalid argument passed.
@@ -194,11 +202,13 @@ Invalid argument passed.
@subheading DESCRIPTION:
-This function deletes the @code{signo} to the specified signal @code{set}.
+This function deletes the signal specified by @code{signo} from the specified
+signal @code{set}.
@subheading NOTES:
-NONE
+The set must be initialized using either @code{sigemptyset} or @code{sigfillset}
+before using this function.
@c
@c
@@ -221,8 +231,10 @@ int sigfillset(
@subheading STATUS CODES:
-@table @b
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+@table @b
@item EINVAL
Invalid argument passed.
@@ -233,10 +245,6 @@ Invalid argument passed.
This function fills the specified signal @code{set} such that all
signals are set.
-@subheading NOTES:
-
-NONE
-
@c
@c
@c
@@ -259,6 +267,10 @@ int sigismember(
@subheading STATUS CODES:
+The function returns either 1 or 0 if completed successfully, otherwise it
+returns -1 and sets @code{errno} to indicate the error. @code{errno} may be set
+to:
+
@table @b
@item EINVAL
@@ -273,7 +285,8 @@ and 0 otherwise.
@subheading NOTES:
-NONE
+The set must be initialized using either @code{sigemptyset} or @code{sigfillset}
+before using this function.
@c
@c
@@ -296,8 +309,10 @@ int sigemptyset(
@subheading STATUS CODES:
-@table @b
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+@table @b
@item EINVAL
Invalid argument passed.
@@ -305,12 +320,7 @@ Invalid argument passed.
@subheading DESCRIPTION:
-This function fills the specified signal @code{set} such that all
-signals are cleared.
-
-@subheading NOTES:
-
-NONE
+This function initializes an empty signal set pointed to by @code{set}.
@c
@c
@@ -335,6 +345,9 @@ int sigaction(
@subheading STATUS CODES:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
@item EINVAL
Invalid argument passed.
@@ -346,10 +359,71 @@ Realtime Signals Extension option not supported.
@subheading DESCRIPTION:
-This function is used to change the action taken by a process on
-receipt of the specfic signal @code{sig}. The new action is
-specified by @code{act} and the previous action is returned
-via @code{oact}.
+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 @code{sigaction} has the following members:
+
+@table @code
+
+@item void(*)(int) sa_handler
+Pointer to a signal-catching function or one of the macros SIG_IGN or SIG_DFL.
+
+@item sigset_t sa_mask
+Additional set of signals to be blocked during execution of signal-catching function.
+
+@item int sa_flags
+Special flags to affect behavior of signal.
+
+@item void(*)(int, siginfo_t*, void*) sa_sigaction
+Alternative pointer to a signal-catching function.
+
+@end table
+
+@code{sa_handler} and @code{sa_sigaction} should never be used at the same time as their storage may overlap.
+
+If the @code{SA_SIGINFO} flag (see below) is set in @code{sa_flags}, the
+@code{sa_sigaction} field specifies a signal-catching function, otherwise
+@code{sa_handler} specifies the action to be associated with the signal, which
+may be a signal-catching function or one of the macros @code{SIG_IGN} or
+@code{SIG_DFN}.
+
+The following flags can be set in the @code{sa_flags} field:
+
+@table @code
+
+@c I found no evidence that other flags are used in the source code.
+@c I did a fulltext search in cpukit/posix/, maybe I looked in the wrong place?
+@item SA_SIGINFO
+If not set, the signal-catching function should be declared as @code{void
+func(int signo)} and the address of the function should be set in
+@code{sa_handler}. If set, the signal-catching function should be declared as
+@code{void func(int signo, siginfo_t* info, void* context)} and the address of
+the function should be set in @code{sa_sigaction}.
+
+@end table
+
+The prototype of the @code{siginfo_t} structure is the following:
+@example
+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 */
+@}
+@end example
@subheading NOTES:
@@ -377,6 +451,9 @@ int pthread_kill(
@subheading STATUS CODES:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
@item ESRCH
@@ -389,11 +466,11 @@ Invalid argument passed.
@subheading DESCRIPTION:
-This functions sends the specified signal @code{sig} to @code{thread}.
+This functions sends the specified signal @code{sig} to a thread referenced
+to by @code{thread}.
-@subheading NOTES:
+If the signal code is @code{0}, arguments are validated and no signal is sent.
-NONE
@c
@c
@@ -418,6 +495,9 @@ int sigprocmask(
@subheading STATUS CODES:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
@item EINVAL
@@ -447,13 +527,17 @@ The set of currently blocked signals is set to @code{set}.
@end table
-If @code{oset} is not @code{NULL}, then the set of blocked signals
-prior to this call is returned in @code{oset}.
+If @code{oset} is not @code{NULL}, then the set of blocked signals prior to
+this call is returned in @code{oset}. If @code{set} is @b{NULL}, no change is
+done, allowing to examine the set of currently blocked signals.
@subheading 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().
+
@c
@c
@c
@@ -476,7 +560,12 @@ int pthread_sigmask(
@end example
@subheading STATUS CODES:
+
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
+
@item EINVAL
Invalid argument passed.
@@ -503,8 +592,9 @@ The set of currently blocked signals is set to @code{set}.
@end table
-If @code{oset} is not @code{NULL}, then the set of blocked signals
-prior to this call is returned in @code{oset}.
+If @code{oset} is not @code{NULL}, then the set of blocked signals prior to
+this call is returned in @code{oset}. If @code{set} is @b{NULL}, no change is
+done, allowing to examine the set of currently blocked signals.
@subheading NOTES:
@@ -533,6 +623,10 @@ int kill(
@end example
@subheading STATUS CODES:
+
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
@item EINVAL
Invalid argument passed.
@@ -551,7 +645,8 @@ This function sends the signal @code{sig} to the process @code{pid}.
@subheading NOTES:
-NONE
+Since RTEMS is a single-process system, a signal can only be sent to the calling
+process (i.e. the current node).
@c
@c
@@ -574,8 +669,8 @@ int sigpending(
@subheading STATUS CODES:
-On error, this routine returns -1 and sets @code{errno} to one of
-the following:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
@table @b
@@ -590,10 +685,6 @@ 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 @code{set}.
-@subheading NOTES:
-
-NONE
-
@c
@c
@c
@@ -615,8 +706,8 @@ int sigsuspend(
@subheading STATUS CODES:
-On error, this routine returns -1 and sets @code{errno} to one of
-the following:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
@table @b
@@ -629,11 +720,7 @@ Signal interrupted this function.
This function temporarily replaces the signal mask for the process
with that specified by @code{sigmask} and blocks the calling thread
-until the signal is raised.
-
-@subheading NOTES:
-
-NONE
+until a signal is raised.
@c
@c
@@ -654,8 +741,8 @@ int pause( void );
@subheading STATUS CODES:
-On error, this routine returns -1 and sets @code{errno} to one of
-the following:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
@table @b
@@ -669,10 +756,6 @@ Signal interrupted this function.
This function causes the calling thread to be blocked until an
unblocked signal is received.
-@subheading NOTES:
-
-NONE
-
@c
@c
@c
@@ -694,7 +777,12 @@ int sigwait(
@end example
@subheading STATUS CODES:
+
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
+
@item EINVAL
Invalid argument passed.
@@ -709,11 +797,6 @@ This function selects a pending signal based on the set specified in
@code{set}, atomically clears it from the set of pending signals, and
returns the signal number for that signal in @code{sig}.
-
-@subheading NOTES:
-
-NONE
-
@c
@c
@c
@@ -735,7 +818,12 @@ int sigwaitinfo(
@end example
@subheading STATUS CODES:
+
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
+
@item EINTR
Signal interrupted this function.
@@ -747,9 +835,23 @@ This function selects a pending signal based on the set specified in
@code{set}, atomically clears it from the set of pending signals, and
returns information about that signal in @code{info}.
-@subheading NOTES:
-
-NONE
+The prototype of the @code{siginfo_t} structure is the following:
+@example
+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 */
+@}
+@end example
@c
@c
@@ -773,7 +875,12 @@ int sigtimedwait(
@end example
@subheading STATUS CODES:
+
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
+
@item EAGAIN
Timed out while waiting for the specified signal set.
@@ -792,6 +899,15 @@ This function selects a pending signal based on the set specified in
returns information about that signal in @code{info}. The calling thread
will block up to @code{timeout} waiting for the signal to arrive.
+The @code{timespec} structure is defined as follows:
+@example
+struct timespec
+@{
+ time_t tv_sec; /* Seconds */
+ long tv_nsec; /* Nanoseconds */
+@}
+@end example
+
@subheading NOTES:
If @code{timeout} is NULL, then the calling thread will wait forever for
@@ -820,6 +936,9 @@ int sigqueue(
@subheading STATUS CODES:
+The function returns 0 on success, otherwise it returns -1 and sets
+@code{errno} to indicate the error. @code{errno} may be set to:
+
@table @b
@item EAGAIN
@@ -845,9 +964,19 @@ The process pid does not exist.
This function sends the signal specified by @code{signo} to the
process @code{pid}
+The @code{sigval} union is specified as:
+@example
+union sigval
+@{
+ int sival_int; /* Integer signal value */
+ void* sival_ptr; /* Pointer signal value */
+@}
+@end example
+
@subheading NOTES:
-NONE
+Since RTEMS is a single-process system, a signal can only be sent to the calling
+process (i.e. the current node).
@c
@c
@@ -886,7 +1015,7 @@ be generated after the number of seconds specified by
@subheading NOTES:
Alarm requests do not queue. If @code{alarm} is called while
-a previous request is outstanding, the call will result in
+a previous request is outstanding, the call will result in
rescheduling the time at which the @code{SIGALRM} signal
will be generated.
@@ -936,7 +1065,7 @@ with a period in microseconds specified by @code{interval}.
@subheading NOTES:
Alarm requests do not queue. If @code{alarm} is called while
-a previous request is outstanding, the call will result in
+a previous request is outstanding, the call will result in
rescheduling the time at which the @code{SIGALRM} signal
will be generated.