sigsuspend(2) - Linux manual page (original) (raw)

sigsuspend(2) System Calls Manual sigsuspend(2)

NAME top

   sigsuspend, rt_sigsuspend - wait for a signal

LIBRARY top

   Standard C library (_libc_, _-lc_)

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
   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 top

   **sigsuspend**() always returns -1, with _[errno](../man3/errno.3.html)_ 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)](../man7/signal.7.html).

STANDARDS top

   POSIX.1-2008.

HISTORY top

   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 sigsett 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 sigsett type. The new system call takes a second argument, sizet sigsetsize, which specifies the size in bytes of the signal set in mask. This argument is currently required to have the value sizeof(sigsett) (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 top

   Normally, **sigsuspend**() is used in conjunction with [sigprocmask(2)](../man2/sigprocmask.2.html)
   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)](../man2/sigprocmask.2.html).  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)](../man2/sigprocmask.2.html) (in the _oldset_ argument).

   See [sigsetops(3)](../man3/sigsetops.3.html) for details on manipulating signal sets.

SEE ALSO top

   [kill(2)](../man2/kill.2.html), [pause(2)](../man2/pause.2.html), [sigaction(2)](../man2/sigaction.2.html), [signal(2)](../man2/signal.2.html), [sigprocmask(2)](../man2/sigprocmask.2.html),
   [sigwaitinfo(2)](../man2/sigwaitinfo.2.html), [sigsetops(3)](../man3/sigsetops.3.html), [sigwait(3)](../man3/sigwait.3.html), [signal(7)](../man7/signal.7.html)

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Linux man-pages 6.10 2024-07-23 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)