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)