rt_sigsuspend − wait for a signal
sigsuspend(const sigset_t *mask);
Macro Requirements for glibc (see
_POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE ||
temporarily replaces the signal mask of the calling process
with the mask given by mask and then suspends the
process 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
It is not
possible to block SIGKILL or SIGSTOP;
specifying these signals in mask, has no effect on
the process’s signal mask.
always returns −1, with errno set to indicate
the error (normally, EINTR).
mask points to memory
which is not a valid part of the process address space.
The call was interrupted by a signal.
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).
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.
pause(2), sigaction(2), signal(2),
sigsetops(3), sigwait(3), signal(7)
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