sigsuspend(2) — Linux manual page

sigsuspend(2)              System Calls Manual             sigsuspend(2)

NAME

       sigsuspend, rt_sigsuspend - wait for a signal

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <signal.h>

       int sigsuspend(const sigset_t *mask);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       sigsuspend():
           _POSIX_C_SOURCE

DESCRIPTION

       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.

RETURN VALUE

       sigsuspend() always returns -1, with errno set to indicate the
       error (normally, EINTR).

ERRORS

       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).

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2001.

   C library/kernel differences
       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.

NOTES

       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.

SEE ALSO

       kill(2), pause(2), sigaction(2), signal(2), sigprocmask(2),
       sigwaitinfo(2), sigsetops(3), sigwait(3), signal(7)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                  sigsuspend(2)

Pages that refer to this page: pause(2), sigaction(2), signal(2), sigpending(2), sigprocmask(2), syscalls(2), sigpause(3), sigset(3), sigsetops(3), sigwait(3), signal(7), signal-safety(7), system_data_types(7)

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