SIGSETJMP(P) POSIX Programmer's Manual SIGSETJMP(P)
sigsetjmp - set jump point for a non-local goto
int sigsetjmp(sigjmp_buf env, int savemask);
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.
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.
No errors are defined.
The following sections are informative.
The distinction between setjmp()/ longjmp() and sigsetjmp()/ siglongjmp() is only signifi-
cant 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.
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 corre-
sponding 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
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.
siglongjmp() , signal() , sigprocmask() , sigsuspend() , the Base Definitions volume of
IEEE Std 1003.1-2001, <setjmp.h>
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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 SIGSETJMP(P)