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); |
![[Note]](../stylesheet/note.png) |
Note | ||
|---|---|---|---|
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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.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
|
|
Thread safety | MT-Safe |
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.