NAME
_longjmp _setjmp
— non-local goto
SYNOPSIS
void _longjmp(jmp_buf env, int val); int _setjmp(jmp_buf env);
DESCRIPTION
The _longjmp () and
_setjmp () functions shall be equivalent to
longjmp(3) and setjmp(3), respectively,
with the additional restriction that _longjmp () and
_setjmp () shall not manipulate the signal mask.
If _longjmp () is called even
though env was never
initialized by a call to _setjmp (), or when the
last such call was in a function that has since returned, the results are
undefined.
RETURN VALUE
Refer to longjmp(3) and setjmp(3).
ERRORS
No errors are defined.
EXAMPLES
None.
APPLICATION USAGE
If _longjmp () is executed and the
environment in which _setjmp () was executed no
longer exists, errors can occur. The conditions under which the environment
of the _setjmp () no longer exists include exiting
the function that contains the _setjmp () call, and
exiting an inner block with temporary storage. This condition might not be
detectable, in which case the _longjmp () occurs
and, if the environment no longer exists, the contents of the temporary
storage of an inner block are unpredictable. This condition might also cause
unexpected process termination. If the function has returned, the results
are undefined.
Passing longjmp(3) a pointer to a buffer not
created by setjmp(3), passing
_longjmp () a pointer to a buffer not created by
_setjmp (), passing siglongjmp(3)
a pointer to a buffer not created by sigsetjmp(3), or
passing any of these three functions a buffer that has been modified by the
user can cause all the problems listed above, and more.
The _longjmp () and
_setjmp () functions are included to support
programs written to historical system interfaces. New applications should
use siglongjmp(3) and sigsetjmp(3)
respectively.
RATIONALE
None.
FUTURE DIRECTIONS
The _longjmp () and
_setjmp () functions may be marked LEGACY in a
future version.
SEE ALSO
longjmp(3), setjmp(3), siglongjmp(3), sigsetjmp(3), the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <setjmp.h>
CHANGE HISTORY
First released in Issue 4, Version 2.
Issue 5
Moved from X/OPEN UNIX extension to BASE.
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