sigpending, rt_sigpending - examine pending signals
Standard C library (libc, -lc)
#include <signal.h>
int sigpending(sigset_t *set);Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
sigpending():
_POSIX_C_SOURCEsigpending() returns the set of signals that are
pending for delivery to the calling thread (i.e., the signals which have
been raised while blocked). The mask of pending signals is returned in
set.
sigpending() returns 0 on success. On failure, -1 is
returned and errno is set to indicate the error.
set points to memory which is not a valid part of the
process address space.
POSIX.1-2008.
POSIX.1-2001.
The original Linux system call was named
sigpending(). However, with the addition of real-time
signals in Linux 2.2, the fixed-size, 32-bit sigset_t argument
supported by that system call was no longer fit for purpose.
Consequently, a new system call, rt_sigpending(), was
added to support an enlarged sigset_t type. The new system call
takes a second argument, size_t sigsetsize, which specifies the
size in bytes of the signal set in set. The glibc
sigpending() wrapper function hides these details from
us, transparently calling rt_sigpending() when the
kernel provides it.
See sigsetops(3) for details on manipulating signal sets.
If a signal is both blocked and has a disposition of "ignored", it is
not added to the mask of pending signals when generated.
The set of signals that is pending for a thread is the union of the set of signals that is pending for that thread and the set of signals that is pending for the process as a whole; see signal(7).
A child created via fork(2) initially has an empty pending signal set; the pending signal set is preserved across an execve(2).
Up to and including glibc 2.2.1, there is a bug in the wrapper function for sigpending() which means that information about pending real-time signals is not correctly returned.
kill(2), sigaction(2), signal(2), sigprocmask(2), sigsuspend(2), sigsetops(3), signal(7)