oracular (3) sigsetjmp.3posix.gz

Provided by: manpages-posix-dev_2017a-2_all bug

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 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>


       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 .