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, Copyright (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.opengroup.org/unix/online.html .