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2011-01-10 Danila Bespalov <danila DOT bespalov AT gmail DOT com>

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* posix_users/posix_users.texi, posix_users/signal.t: Review and
	improve as part of Google Code-In 2010.
This commit is contained in:
Joel Sherrill
2011-01-10 16:14:07 +00:00
parent 174ac5de2e
commit e7620cbd10
3 changed files with 206 additions and 72 deletions
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5
doc/ChangeLog
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@@ -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,

10
doc/posix_users/posix_users.texi
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@@ -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

263
doc/posix_users/signal.t
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@@ -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.