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 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
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/.