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_LONGJMP(3C) Standard C Library Functions _LONGJMP(3C)

NAME

_longjmp, _setjmp - non-local goto

SYNOPSIS

#include <setjmp.h>

void _longjmp(jmp_buf env, int val);

int _setjmp(jmp_buf env);

DESCRIPTION

The _longjmp() and _setjmp() functions are identical to longjmp(3C) and
setjmp(3C), respectively, with the additional restriction that _longjmp()
and _setjmp() do 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 VALUES

Refer to longjmp(3C) and setjmp(3C).

ERRORS

No errors are defined.

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() a pointer to a buffer not created by setjmp(), passing
_longjmp() a pointer to a buffer not created by _setjmp(), passing
siglongjmp(3C) a pointer to a buffer not created by sigsetjmp(3C) 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(3C) and sigsetjmp(3C) respectively.

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