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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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