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 per-
       formed 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(3).

       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 3.53 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)