sigpending, rt_sigpending - examine pending signals
#include <signal.h>
int sigpending(sigset_t *set);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
sigpending(): _POSIX_C_SOURCE
sigpending() 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 and -1 on error. In the event of an
error,
errno is set to indicate the cause.
- EFAULT
- set points to memory which is not a valid part of the process
address space.
POSIX.1-2001, POSIX.1-2008.
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).
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.
In versions of glibc up to and including 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)