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 .