_LONGJMP(3P)                                        POSIX Programmer's Manual                                       _LONGJMP(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

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 shall be equivalent to longjmp() and setjmp(), 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() and setjmp().

ERRORS
       No errors are defined.

       The following sections are informative.

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

RATIONALE
       None.

FUTURE DIRECTIONS
       The _longjmp() and _setjmp() functions may be marked LEGACY in a future version.

SEE ALSO
       longjmp(), setjmp(), siglongjmp(), sigsetjmp(), the Base Definitions volume of IEEE Std 1003.1-2001, <setjmp.h>

COPYRIGHT
       Portions  of  this  text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for
       Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6,  Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open  Group
       Standard   is   the   referee   document.   The   original   Standard   can   be   obtained  online  at  http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                  _LONGJMP(3P)