redhat man page for longjmp

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, int val);
       void siglongjmp(sigjmp_buf env, int val);

DESCRIPTION
       longjmp()  and  setjmp()  are  useful for dealing with errors and interrupts encountered in a low-level subroutine of a program.  longjmp()
       restores the environment saved by the last call of setjmp() with the corresponding env argument.  After	longjmp()  is  completed,  program
       execution continues as if 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 argument.  If the sigsetjmp() call that set this  env  used	a  nonzero
       savesigs flag, siglongjmp() also restores the set of blocked signals.

RETURN VALUE
       These functions never return.

CONFORMING TO
       POSIX

NOTES
       POSIX does not specify whether longjmp will restore the signal context.	If you want to save and restore signal masks, use siglongjmp.

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

SEE ALSO
       setjmp(3), sigsetjmp(3)

								    1997-03-02								LONGJMP(3)