sigsuspend(2)



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

NAME
       sigsuspend, rt_sigsuspend - wait for a signal

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
       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 sig-
       nals in mask, has no effect on the process'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).

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

NOTES
       Normally, sigsuspend() is used in conjunction  with  sigprocmask(2)  in
       order  to prevent delivery of a signal during the execution of a criti-
       cal code section.  The caller first blocks the  signals  with  sigproc-
       mask(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 pur-
       pose.  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  sig-
       suspend()  wrapper  function hides these details from us, transparently
       calling rt_sigsuspend() when the kernel provides it.

SEE ALSO
       kill(2), pause(2), sigaction(2),  signal(2),  sigprocmask(2),  sigwait-
       info(2), sigsetops(3), sigwait(3), signal(7)

COLOPHON
       This  page  is  part of release 4.05 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/.

Linux                             2016-03-15                     SIGSUSPEND(2)

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