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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  significant 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
       corresponding 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 original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .