sigsuspend, rt_sigsuspend - wait for a signal
int sigsuspend(const sigset_t *mask);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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
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
sigsuspend() always returns -1, with errno set to indicate the
error (normally, EINTR).
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).
- mask points to memory which is not a valid part of the process
- The call was interrupted by a signal; signal(7).
See sigsetops(3) for details on manipulating signal
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.
This page is part of release 5.01 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/.