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       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 >= 1 || _XOPEN_SOURCE || _POSIX_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).

   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.


       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)


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