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 program.  setjmp()
       saves the stack context/environment in env for later use by longjmp(3).	The stack context will be invalidated 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  con-
       text.

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 3.27 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)