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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 (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       longjmp -- non-local goto
SYNOPSIS
       #include <setjmp.h>
       void longjmp(jmp_buf env, int val);
DESCRIPTION
       The functionality described on this reference page is aligned with  the
       ISO C  standard.  Any  conflict between the requirements described here
       and the ISO C standard is unintentional. This  volume  of  POSIX.1-2008
       defers to the ISO C standard.
       The  longjmp() function shall restore the environment saved by the most
       recent invocation of setjmp() in the same process, with the correspond-
       ing  jmp_buf  argument.  If the most recent invocation of setjmp() with
       the corresponding jmp_buf occurred in another thread, or if there is no
       such  invocation,  or  if  the  function  containing  the invocation of
       setjmp() has terminated execution in the interim, or if the  invocation
       of  setjmp()  was within the scope of an identifier with variably modi-
       fied type and execution has left that scope in the interim, the  behav-
       ior  is  undefined.   It  is unspecified whether longjmp() restores the
       signal mask, leaves the signal mask unchanged, or restores  it  to  its
       value at the time setjmp() was called.
       All  accessible  objects  have  values, and all other components of the
       abstract machine have state (for example, floating-point  status  flags
       and  open  files), as of the time longjmp() was called, except that the
       values of objects of automatic storage duration are unspecified if they
       meet all the following conditions:
        *  They  are  local  to  the  function  containing  the  corresponding
           setjmp() invocation.
        *  They do not have volatile-qualified type.
        *  They are changed between  the  setjmp()  invocation  and  longjmp()
           call.
       As it bypasses the usual function call and return mechanisms, longjmp()
       shall execute correctly in contexts of interrupts, signals, and any  of
       their  associated  functions.  However,  if longjmp() is invoked from a
       nested signal handler (that is, from a function invoked as a result  of
       a signal raised during the handling of another signal), the behavior is
       undefined.
       The effect of a call to longjmp() where initialization of  the  jmp_buf
       structure was not performed in the calling thread is undefined.
RETURN VALUE
       After  longjmp()  is  completed,  program execution continues as if the
       corresponding invocation of setjmp() had just returned the value speci-
       fied by val.  The longjmp() function shall not cause setjmp() to return
       0; if val is 0, setjmp() shall return 1.
ERRORS
       No errors are defined.
       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       Applications whose behavior depends on the value  of  the  signal  mask
       should not use longjmp() and setjmp(), since their effect on the signal
       mask is unspecified,  but  should  instead  use  the  siglongjmp()  and
       sigsetjmp() functions (which can save and restore the signal mask under
       application control).
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       setjmp(), sigaction(), siglongjmp(), sigsetjmp()
       The Base Definitions volume of POSIX.1-2008, <setjmp.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) 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.unix.org/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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                          LONGJMP(3P)