| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
LONGJMP(3) Linux Programmer's Manual LONGJMP(3)
longjmp, siglongjmp - nonlocal jump to a saved stack context
#include <setjmp.h>
void longjmp(jmp_buf env, int val);
void siglongjmp(sigjmp_buf env, int val);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
siglongjmp(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_C_SOURCE
longjmp() and setjmp(3) 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(3) with the corresponding env
argument. After longjmp() is completed, program execution continues as if the
corresponding call of setjmp(3) 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, and only if, the sigsetjmp(3) call that set this env used a nonzero
savesigs flag, siglongjmp() also restores the signal mask that was saved by
sigsetjmp(3).
These functions never return.
C89, C99, and POSIX.1-2001 specify longjmp(). POSIX.1-2001 specifies
siglongjmp().
POSIX does not specify whether longjmp() will restore the signal context (see
setjmp(3) for some more details). If you want to portably save and restore
signal masks, use sigsetjmp() and siglongjmp().
The values of automatic variables are unspecified after a call to longjmp() if
they meet all the following criteria:
o they are local to the function that made the corresponding setjmp(3) call;
o their values are changed between the calls to setjmp(3) and longjmp(); and
o they are not declared as volatile.
Analogous remarks apply for siglongjmp().
longjmp() and siglongjmp() make programs hard to understand and maintain. If
possible an alternative should be used.
setjmp(3), sigsetjmp(3)
This page is part of release 3.32 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/.
2009-01-13 LONGJMP(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface