NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

SIGSUSPEND(2)             Linux Programmer's Manual            SIGSUSPEND(2)

NAME         top

       sigsuspend, rt_sigsuspend - wait for a signal

SYNOPSIS         top

       #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         top

       sigsuspend() 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 sigsuspend().

       It is not possible to block SIGKILL or SIGSTOP; specifying these
       signals in mask, has no effect on the process's signal mask.

RETURN VALUE         top

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

ERRORS         top

       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).

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008.

NOTES         top

       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.

   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.

SEE ALSO         top

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

COLOPHON         top

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Linux                            2016-03-15                    SIGSUSPEND(2)