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); |
![[Note]](../stylesheet/note.png) |
Note | ||
|---|---|---|---|
|
DESCRIPTION
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 the sigsetjmp(3) call that set
this env used a
nonzero savesigs
flag, siglongjmp() also
restores the set of blocked signals.
NOTES
POSIX does not specify whether longjmp() will restore the signal context.
If you want to save and restore signal masks, use
siglongjmp().
The values of automatic variables are unspecified after a
call to longjmp() if they meet
all the following criteria:
Analogous remarks apply for siglongjmp().
longjmp() and siglongjmp() make programs hard to
understand and maintain. If possible an alternative should be
used.