SETJMP

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);

DESCRIPTION

setjmp() and longjmp() 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(). The stack context will be invalidated if the function which called setjmp() returns. sigsetjmp() is similar to setjmp(). If savesigs is nonzero, the set of blocked signals is saved in env and will be restored if a siglongjmp() is later performed with this env.

RETURN VALUE

setjmp() and sigsetjmp() return 0 if returning directly, and non-zero when returning from longjmp() using the saved context.

CONFORMING TO

POSIX, ISO 9899 (C99)

NOTES

POSIX does not specify whether setjmp will save the signal context. (In SYSV it will not. In BSD4.3 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.