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 .

IEEE/The Open Group                                   2003                                          SIGSETJMP(P)