sigpending(2)                 System Calls Manual                sigpending(2)

NAME
       sigpending, rt_sigpending - examine pending signals

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <signal.h>

       int sigpending(sigset_t *set);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sigpending():
           _POSIX_C_SOURCE

DESCRIPTION
       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.

RETURN VALUE
       sigpending() returns 0 on success.  On failure, -1 is returned and
       errno is set to indicate the error.

ERRORS
       EFAULT set points to memory which is not a valid part of the process
              address space.

STANDARDS
       POSIX.1-2008.

HISTORY
       POSIX.1-2001.

   C library/kernel differences
       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.

NOTES
       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).

BUGS
       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.

SEE ALSO
       kill(2), sigaction(2), signal(2), sigprocmask(2), sigsuspend(2),
       sigsetops(3), signal(7)

Linux man-pages 6.7               2023-10-31                     sigpending(2)