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LONGJMP(P)			    POSIX Programmer's Manual			       LONGJMP(P)

NAME
       longjmp - non-local goto

SYNOPSIS
       #include <setjmp.h>

       void longjmp(jmp_buf env, int val);

DESCRIPTION
       The  longjmp()  function shall restore the environment saved by the most recent invocation
       of setjmp() in the same thread, with the corresponding jmp_buf argument. 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 modified type and execution has left that scope in the interim,
       the behavior 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  unspeci-
       fied 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 cor-
       rectly 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  unde-
       fined.

       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  invoca-
       tion  of  setjmp()  had	just  returned the value specified 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
       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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				       LONGJMP(P)
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