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



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

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 .



IEEE/The Open Group                  2017                          _LONGJMP(3)
