LONGJMP(3) Library functions LONGJMP(3)
NAME
longjmp, siglongjmp - non-local jump to a saved stack context
SYNOPSIS
#include <setjmp.h>
void longjmp(jmp_buf env(1,3), int val);
void siglongjmp(sigjmp_buf env(1,3), int val);
DESCRIPTION
longjmp() and setjmp() are useful for dealing with errors and inter-
rupts encountered in(1,8) a low-level subroutine of a program. longjmp()
restores the environment saved by the last call of setjmp() with the
corresponding env(1,3) argument. After longjmp() is completed, program exe-
cution continues as if(3,n) the corresponding call of setjmp() had just
returned the value val. longjmp() cannot cause 0 to be returned. If
longjmp is invoked with a second argument of 0, 1 will be returned
instead.
siglongjmp() is similar to longjmp() except for the type of its env(1,3)
argument. If the sigsetjmp() call that set(7,n,1 builtins) this env(1,3) used a nonzero
savesigs flag, siglongjmp() also restores the set(7,n,1 builtins) of blocked signals.
RETURN VALUE
These functions never return.
CONFORMING TO
POSIX
NOTES
POSIX does not specify whether longjmp will restore the signal(2,7) context.
If you want to save and restore signal(2,7) masks, use siglongjmp.
longjmp() and siglongjmp() make programs hard to understand and main-
tain. If possible an alternative should be used.
SEE ALSO
setjmp(3), sigsetjmp(3)
1997-03-02 LONGJMP(3)