sigemptyset(3)

NAME

   sigemptyset,  sigfillset,  sigaddset,  sigdelset,  sigismember  - POSIX
   signal set operations

SYNOPSIS

   #include <signal.h>

   int sigemptyset(sigset_t *set);

   int sigfillset(sigset_t *set);

   int sigaddset(sigset_t *set, int signum);

   int sigdelset(sigset_t *set, int signum);

   int sigismember(const sigset_t *set, int signum);

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

   sigemptyset(), sigfillset(), sigaddset(), sigdelset(), sigismember():
       _POSIX_C_SOURCE

DESCRIPTION

   These functions allow the manipulation of POSIX signal sets.

   sigemptyset() initializes the signal set given by set  to  empty,  with
   all signals excluded from the set.

   sigfillset() initializes set to full, including all signals.

   sigaddset()  and  sigdelset() add and delete respectively signal signum
   from set.

   sigismember() tests whether signum is a member of set.

   Objects of type sigset_t must  be  initialized  by  a  call  to  either
   sigemptyset()  or  sigfillset()  before  being  passed to the functions
   sigaddset(), sigdelset() and  sigismember()  or  the  additional  glibc
   functions    described   below   (sigisemptyset(),   sigandset(),   and
   sigorset()).  The results are undefined if this is not done.

RETURN VALUE

   sigemptyset(), sigfillset(), sigaddset(), and sigdelset() return  0  on
   success and -1 on error.

   sigismember()  returns  1  if signum is a member of set, 0 if signum is
   not a member, and -1 on error.

   On error, these functions set errno to indicate the cause of the error.

ERRORS

   EINVAL sig is not a valid signal.

ATTRIBUTES

   For  an  explanation  of  the  terms  used   in   this   section,   see
   attributes(7).

   ┌────────────────────────────────┬───────────────┬─────────┐
   │Interface                       │ Attribute     │ Value   │
   ├────────────────────────────────┼───────────────┼─────────┤
   │sigemptyset(), sigfillset(),    │ Thread safety │ MT-Safe │
   │sigaddset(), sigdelset(),       │               │         │
   │sigismember(), sigisemptyset(), │               │         │
   │sigorset(), sigandset()         │               │         │
   └────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

   POSIX.1-2001, POSIX.1-2008.

NOTES

   When creating a filled signal set, the glibc sigfillset() function does
   not include the two real-time  signals  used  internally  by  the  NPTL
   threading implementation.  See nptl(7) for details.

   Glibc extensions
   If  the  _GNU_SOURCE  feature  test  macro  is defined, then <signal.h>
   exposes three other functions for manipulating signal sets:

   int sigisemptyset(const sigset_t *set);
   int sigorset(sigset_t *dest, const sigset_t *left,
                 const sigset_t *right);
   int sigandset(sigset_t *dest, const sigset_t *left,
                 const sigset_t *right);

   sigisemptyset() returns 1 if set contains no signals, and 0 otherwise.

   sigorset() places the union  of  the  sets  left  and  right  in  dest.
   sigandset() places the intersection of the sets left and right in dest.
   Both functions return 0 on success, and -1 on failure.

   These functions are nonstandard (a few other  systems  provide  similar
   functions) and their use should be avoided in portable applications.

SEE ALSO

   sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2)

COLOPHON

   This  page  is  part of release 4.09 of the Linux man-pages project.  A
   description of the project, information about reporting bugs,  and  the
   latest     version     of     this    page,    can    be    found    at
   https://www.kernel.org/doc/man-pages/.

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