LONGJMP(3) manual page
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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(3)
and siglongjmp().
The values of automatic variables are unspecified after a call to longjmp()
if they meet all the following criteria:
- they are local to the function
that made the corresponding setjmp(3)
call;
- their values are changed between
the calls to setjmp(3)
and longjmp(); and
- 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
3.78 of the Linux man-pages project. A description of the project, information
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