SETJMP(3)

NAME
setjmp, sigsetjmp - save stack context for non-local 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)):

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 savesigs is non-zero, the set of blocked signals 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 non-zero when returning from longjmp(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 context. (In System V it will not. In 4.3BSD it will, and there is a function _setjmp that will not.) If you want to save signal masks, use sigsetjmp().

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

SEE ALSO
longjmp(3), siglongjmp(3)

COLOPHON
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