sigsuspend, rt_sigsuspend - wait for a signal
#include <signal.h>
int sigsuspend(const sigset_t *mask);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
sigsuspend(): _POSIX_C_SOURCE
sigsuspend() temporarily replaces the signal mask of the calling thread
with the mask given by
mask and then suspends the thread until delivery
of a signal whose action is to invoke a signal handler or to terminate a
process.
If the signal terminates the process, then
sigsuspend() does not return.
If the signal is caught, then
sigsuspend() returns after the signal
handler returns, and the signal mask is restored to the state before the call
to
sigsuspend().
It is not possible to block
SIGKILL or
SIGSTOP; specifying these
signals in
mask, has no effect on the thread's signal mask.
sigsuspend() always returns -1, with
errno set to indicate the
error (normally,
EINTR).
- EFAULT
- mask points to memory which is not a valid part of the process
address space.
- EINTR
- The call was interrupted by a signal; signal(7).
POSIX.1-2001, POSIX.1-2008.
Normally,
sigsuspend() is used in conjunction with
sigprocmask(2)
in order to prevent delivery of a signal during the execution of a critical
code section. The caller first blocks the signals with
sigprocmask(2).
When the critical code has completed, the caller then waits for the signals by
calling
sigsuspend() with the signal mask that was returned by
sigprocmask(2) (in the
oldset argument).
See
sigsetops(3) for details on manipulating signal sets.
The original Linux system call was named
sigsuspend(). However, with the
addition of real-time signals in Linux 2.2, the fixed-size, 32-bit
sigset_t type supported by that system call was no longer fit for
purpose. Consequently, a new system call,
rt_sigsuspend(), 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
mask. This argument is currently required to have the
value
sizeof(sigset_t) (or the error
EINVAL results). The glibc
sigsuspend() wrapper function hides these details from us,
transparently calling
rt_sigsuspend() when the kernel provides it.
kill(2),
pause(2),
sigaction(2),
signal(2),
sigprocmask(2),
sigwaitinfo(2),
sigsetops(3),
sigwait(3),
signal(7)