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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 (consult 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  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 save-
       mask 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  restric-
       tions 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 exist-
       ing  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  consid-
       ered worthy of standardization.
FUTURE DIRECTIONS
       None.
SEE ALSO
       pthread_sigmask(), siglongjmp(), signal(), sigsuspend()
       The Base Definitions volume of POSIX.1-2008, <setjmp.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  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.unix.org/online.html .
       Any typographical or formatting errors that appear  in  this  page  are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors,  see  https://www.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                        SIGSETJMP(3P)