sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - POSIX signal set operations
#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
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.
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.
signum
is not a valid signal.
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value |
sigemptyset(), sigfillset(), sigaddset(), sigdelset(), sigismember(), sigisemptyset(), sigorset(), sigandset() |
Thread safety | MT-Safe |
POSIX.1-2001, POSIX.1-2008.
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. 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.
sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2)
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