SIGSETJMP
Section: POSIX Programmer's Manual (3P)
Updated: 2017
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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>
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 .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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