SETJMP(3)                                           Linux Programmer's Manual                                          SETJMP(3)



NAME
       setjmp, sigsetjmp - save stack context for nonlocal goto

SYNOPSIS
       #include <setjmp.h>

       int setjmp(jmp_buf env);

       int sigsetjmp(sigjmp_buf env, int savesigs);

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

       setjmp(): see NOTES.
       sigsetjmp(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_C_SOURCE

DESCRIPTION
       setjmp() and longjmp(3) are useful for dealing with errors and interrupts encountered in a low-level subroutine of a pro-
       gram.  setjmp() saves the stack context/environment in env for later use by longjmp(3).  The stack context will be inval-
       idated if the function which called setjmp() returns.

       sigsetjmp()  is similar to setjmp().  If, and only if, savesigs is nonzero, the process's current signal mask is saved in
       env and will be restored if a siglongjmp(3) is later performed with this env.

RETURN VALUE
       setjmp() and sigsetjmp() return 0 if returning directly, and nonzero when  returning  from  longjmp(3)  or  siglongjmp(3)
       using the saved context.

CONFORMING TO
       C89, C99, and POSIX.1-2001 specify setjmp().  POSIX.1-2001 specifies sigsetjmp().

NOTES
       POSIX  does  not  specify  whether  setjmp() will save the signal mask.  In System V it will not.  In 4.3BSD it will, and
       there is a function _setjmp that will not.  By default, Linux/glibc follows the System V behavior, but the  BSD  behavior
       is  provided  if the _BSD_SOURCE feature test macro is defined and none of _POSIX_SOURCE, _POSIX_C_SOURCE, _XOPEN_SOURCE,
       _XOPEN_SOURCE_EXTENDED, _GNU_SOURCE, or _SVID_SOURCE is defined.

       If you want to portably save and restore signal masks, use sigsetjmp() and siglongjmp().

       setjmp() and sigsetjmp() make programs hard to understand and maintain.  If possible an alternative should be used.

SEE ALSO
       longjmp(3), siglongjmp(3)

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



                                                           2009-06-26                                                  SETJMP(3)