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



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

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
       pthread__sigmask(), siglongjmp(), signal(), sigsuspend()

       The Base Definitions volume of POSIX.1-2017, <setjmp.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       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.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                         SIGSETJMP(3)
