PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult 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 removed in a future version.

SEE ALSO

       longjmp(), setjmp(), siglongjmp(), sigsetjmp()

       The Base Definitions volume of POSIX.1‐2017, <setjmp.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1-2017,  Standard  for  Information Technology -- Portable Operating System Interface
       (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C)  2018  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 .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .