SIGSETJMP(3P)                                       POSIX Programmer's Manual                                      SIGSETJMP(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

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  sig-
       longjmp(), 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  correspond-
       ing  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  question-
       able 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,  Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                 SIGSETJMP(3P)