120 lines
4.8 KiB
Groff
120 lines
4.8 KiB
Groff
|
.\" Copyright (c) 1998 HD Associates, Inc.
|
||
|
|
.\" All rights reserved.
|
||
|
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
||
|
|
.\" documentation and/or other materials provided with the distribution.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
||
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
.\" SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.\" $Id: posix4.9,v 1.8 1998/01/02 19:22:52 alex Exp $
|
||
|
|
.Dd March 1, 1998
|
||
|
|
.Dt POSIX.4 9
|
||
|
|
.Os FreeBSD 3.0
|
||
|
|
.Sh NAME
|
||
|
|
.Nm posix4
|
||
|
|
.Nd "POSIX.4 extensions"
|
||
|
|
.Sh DESCRIPTION
|
||
|
|
POSIX.4 adds real time extensions and some commonly used
|
||
|
|
Berkeley extensions to POSIX.1
|
||
|
|
This section contains information about the the
|
||
|
|
POSIX.4 extensions to the system.
|
||
|
|
.Sh STATUS
|
||
|
|
March 1, 1998 adds the header file changes to 3.0. There should be no
|
||
|
|
visible differences as long as _POSIX_VERSION is left at 199009L and
|
||
|
|
no one builds kernels with a POSIX4 option.
|
||
|
|
.Pp
|
||
|
|
If you are working with something defined in POSIX.4 then there is a good
|
||
|
|
chance we conflict. If you have the time then set
|
||
|
|
_POSIX_VERSION to 199309L in /etc/make.conf and see that your work
|
||
|
|
fits with mine.
|
||
|
|
.Pp
|
||
|
|
Since this only brings in the headers I'm only explaining the feature
|
||
|
|
test options.
|
||
|
|
.Sh SPECIFYING THE VERSION
|
||
|
|
There are three manifest constants that set the version and programming interface
|
||
|
|
for POSIX.4.
|
||
|
|
.Bd -literal -offset 0i
|
||
|
|
_POSIX_VERSION
|
||
|
|
.Ed
|
||
|
|
specifies the system for which the system is built. The default
|
||
|
|
is POSIX.1 and is 199009L. POSIX.4 is 199309L. This defines
|
||
|
|
the base features of the operating system.
|
||
|
|
.Bd -literal -offset 0i
|
||
|
|
_POSIX_SOURCE
|
||
|
|
.Ed
|
||
|
|
is a macro from POSIX.1 that can
|
||
|
|
be defined to specify that only POSIX and ANSI functionality should occur
|
||
|
|
in the name space.
|
||
|
|
.Bd -literal -offset 0i
|
||
|
|
_POSIX_C_SOURCE
|
||
|
|
.Ed
|
||
|
|
is a macro from POSIX.4 that can be defined to specify that only
|
||
|
|
POSIX and ANSI functionality from a specific POSIX version should occur
|
||
|
|
in the name space, i.e., if _POSIX_VERSION is 199309L (POSIX.4) but
|
||
|
|
_POSIX_C_SOURCE is 199009L (POSIX.1) then only POSIX.1 features should
|
||
|
|
appear.
|
||
|
|
.Sh PROPERLY HIDING EXTENSIONS
|
||
|
|
.Bd -literal -offset 0i
|
||
|
|
POSIX4_VISIBLE
|
||
|
|
.Ed
|
||
|
|
is a test macro that tries to sort out when extensions should be
|
||
|
|
visible.
|
||
|
|
.Pp
|
||
|
|
In normal C program development
|
||
|
|
only _POSIX_VERSION is set, permitting BSD extensions to
|
||
|
|
appear to the programs. However, when adding new functionality mandated
|
||
|
|
by POSIX.4, it
|
||
|
|
is important to satisfy the requirements added by the
|
||
|
|
new _POSIX_C_SOURCE macro. POSIX4_VISIBLE (not a standard feature test macro)
|
||
|
|
is defined in sys/unistd.h when the combination of _POSIX_VERSION,
|
||
|
|
_POSIX_SOURCE, and _POSIX_C_SOURCE indicate the extensions are in scope.
|
||
|
|
.Pp
|
||
|
|
Since for POSIX to work you must include <unistd.h> which ultimately
|
||
|
|
sets this up header files can always assume this is visible without
|
||
|
|
including anything.
|
||
|
|
.Pp
|
||
|
|
Some traditional BSD headers (e.g., mmap.h) are now specified in POSIX.4.
|
||
|
|
This means that functionality not present in POSIX.4 should now be
|
||
|
|
hidden by testing _POSIX_SOURCE or _POSIX_C_SOURCE. The safest thing
|
||
|
|
is to hide them when _POSIX_C_SOURCE is defined and less than 199309L.
|
||
|
|
Don't bracket the extensions with the POSIX.4 feature test macros.
|
||
|
|
For example, don't conditionalize new memory locking flags with
|
||
|
|
_POSIX_MEMLOCK. It will be too easy for conflicting implementations
|
||
|
|
that don't pay heed to the POSIX.4 flags to sneak into the system.
|
||
|
|
.Sh NON STANDARD TEST MACROS
|
||
|
|
.Bd -literal -offset 0i
|
||
|
|
POSIX4_INCLUDE_MAYBES
|
||
|
|
.Ed
|
||
|
|
requests that all header files that the POSIX.4 spec says a standard
|
||
|
|
header may include should be included. Normally no non-required
|
||
|
|
headers are included. Setting this pre-processor definition should
|
||
|
|
make any compliant program compile without issues of header file
|
||
|
|
inclusion.
|
||
|
|
.Bd -literal -offset 0i
|
||
|
|
POSIX4
|
||
|
|
.Ed
|
||
|
|
is a config option and (currently) a request to build POSIX.4 by
|
||
|
|
setting the _POSIX_VERSION to 199309L in sys/unistd.h.
|
||
|
|
.Sh SEE ALSO
|
||
|
|
.Sh HISTORY
|
||
|
|
The
|
||
|
|
.Nm posix4
|
||
|
|
section manual page appeared in
|
||
|
|
.Fx 3.0 .
|