SIGPENDING(2)             (2017-09-15)              SIGPENDING(2)

          sigpending, rt_sigpending - examine pending signals

          #include <signal.h>

          int sigpending(sigset_t *set);

     Feature Test Macro Requirements for glibc (see

          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.

               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

        C library/kernel differences
          The original Linux system call was named sigpending().  How-
          ever,  with  the addition of real-time signals in Linux 2.2,

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     SIGPENDING(2)             (2017-09-15)              SIGPENDING(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() wrap-
          per 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 cor-
          rectly returned.

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

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