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manual: Document more sigaction flags

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Adds documentation for three-argument handler

Adds remainder of the SA_* flags

Reviewed-by: Florian Weimer <fweimer@redhat.com>
This commit is contained in:
DJ Delorie 2024-12-10 17:07:21 -05:00
parent 50c35842df
commit 87cd94bba4
1 changed files with 39 additions and 0 deletions
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39
manual/signal.texi
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@ -1141,6 +1141,15 @@ This is used in the same way as the @var{action} argument to the
@code{signal} function. The value can be @code{SIG_DFL},
@code{SIG_IGN}, or a function pointer. @xref{Basic Signal Handling}.
@item void (*sa_sigaction) (int @var{signum}, siginfo_t *@var{info}, void *@var{ucontext})
This is an alternate to @code{sa_handler} that is used when the
@code{sa_flags} includes the @code{flag SA_SIGINFO}. Note that this
and @code{sa_handler} overlap; only ever set one at a time.
The contents of the @var{info} and @var{ucontext} structures are
kernel and architecture dependent. Please see
@manpageurl{sigaction,2} for details.
@item sigset_t sa_mask
This specifies a set of signals to be blocked while the handler runs.
Blocking is explained in @ref{Blocking for Handler}. Note that the
@ -1324,6 +1333,24 @@ delivered for both terminated children and stopped children.
Setting this flag for a signal other than @code{SIGCHLD} has no effect.
@end deftypevr
@deftypevr Macro int SA_NOCLDWAIT
This flag is meaningful only for the @code{SIGCHLD} signal. When the
flag is set, the terminated child will not wait for the parent to reap
it, or become a zombie if not reaped. The child will instead be
reaped by the kernel immediately on termination, similar to setting
SIGCHLD to SIG_IGN.
Setting this flag for a signal other than @code{SIGCHLD} has no effect.
@end deftypevr
@deftypevr Macro int SA_NODEFER
Normally a signal is added to the signal mask while running its own
handler; this negates that, so that the same signal can be received
while it's handler is running. Note that if the signal is included in
@code{sa_mask}, it is masked regardless of this flag. Only useful when
assigning a function as a signal handler.
@end deftypevr
@deftypevr Macro int SA_ONSTACK
@standards{BSD, signal.h}
If this flag is set for a particular signal number, the system uses the
@ -1332,6 +1359,12 @@ If a signal with this flag arrives and you have not set a signal stack,
the normal user stack is used instead, as if the flag had not been set.
@end deftypevr
@deftypevr Macro int SA_RESETHAND
Resets the handler for a signal to SIG_DFL, at the moment specified
handler function begins. I.e. the handler is called once, then the
action resets.
@end deftypevr
@deftypevr Macro int SA_RESTART
@standards{BSD, signal.h}
This flag controls what happens when a signal is delivered during
@ -1347,6 +1380,12 @@ clear, returning from a handler makes the function fail.
@xref{Interrupted Primitives}.
@end deftypevr
@deftypevr Macro int SA_SIGINFO
Indicates that the @code{sa_sigaction} three-argument form of the
handler should be used in setting up a handler instead of the
one-argument @code{sa_handler} form.
@end deftypevr
@node Initial Signal Actions
@subsection Initial Signal Actions
@cindex initial signal actions