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

NAME
       sigsetjmp - set jump point for a non-local goto

SYNOPSIS
       #include <setjmp.h>

       int sigsetjmp(sigjmp_buf env, int savemask);

DESCRIPTION
       The sigsetjmp() function shall be equivalent to the setjmp() function, except as follows:

	* References to setjmp() are equivalent to sigsetjmp().

	* References to longjmp() are equivalent to siglongjmp().

	* If the value of the savemask argument is not 0, sigsetjmp() shall also save the current
	  signal mask of the calling thread as part of the calling environment.

RETURN VALUE
       If the return is from a successful direct invocation, sigsetjmp() shall return 0.  If  the
       return is from a call to siglongjmp(), sigsetjmp() shall return a non-zero value.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The distinction between setjmp()/ longjmp() and sigsetjmp()/ siglongjmp() is only signifi-
       cant for programs which use sigaction(), sigprocmask(), or sigsuspend().

       Note that since this function is defined in terms of setjmp(), if savemask is zero, it  is
       unspecified whether the signal mask is saved.

RATIONALE
       The  ISO C  standard  specifies various restrictions on the usage of the setjmp() macro in
       order to permit implementors to recognize the name in the compiler and  not  implement  an
       actual function. These same restrictions apply to the sigsetjmp() macro.

       There are processors that cannot easily support these calls, but this was not considered a
       sufficient reason to exclude them.

       4.2 BSD, 4.3 BSD,  and  XSI-conformant  systems	provide  functions  named  _setjmp()  and
       _longjmp()  that,  together with setjmp() and longjmp(), provide the same functionality as
       sigsetjmp() and siglongjmp(). On those systems, setjmp() and longjmp()  save  and  restore
       signal  masks,  while _setjmp() and _longjmp() do not. On System V Release 3 and in corre-
       sponding issues of the SVID, setjmp() and longjmp() are explicitly defined not to save and
       restore	signal masks. In order to permit existing practice in both cases, the relation of
       setjmp() and longjmp() to signal masks is not specified, and a new  set	of  functions  is
       defined instead.

       The  longjmp()  and  siglongjmp()  functions operate as in the previous issue provided the
       matching setjmp() or sigsetjmp() has been performed in the same	thread.  Non-local  jumps
       into contexts saved by other threads would be at best a questionable practice and were not
       considered worthy of standardization.

FUTURE DIRECTIONS
       None.

SEE ALSO
       siglongjmp() , signal() , sigprocmask() , sigsuspend() , 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				     SIGSETJMP(P)
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