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Re: [patch] manual/conf.texi, sync _POSIX_PATH_MAX with headervalue
- To: Mark Brown <broonie at sirena dot org dot uk>, GNU C Library <libc-alpha at sourceware dot cygnus dot com>
- Subject: Re: [patch] manual/conf.texi, sync _POSIX_PATH_MAX with headervalue
- From: Mark Brown <bmark at us dot ibm dot com>
- Date: Wed, 10 Jan 2001 10:50:40 -0600
Mark Brown wrote:
> On Mon, Jan 08, 2001 at 07:40:24PM -0500, Ben Collins wrote:
>
>> @comment POSIX.1
>> @item _POSIX_PATH_MAX
>> The most restrictive limit permitted by POSIX for the maximum number of
>> -bytes in a file name. The value of this constant is @code{255}.
>> +bytes in a file name. POSIX defines this to be no less than 255. In
>> +the GNU C library, the value of this constant is @code{256}.
>
> What prompted this patch was a bug report from me complaining that POSIX
> (or at least, SUS2) requires that _POSIX_PATH_MAX be exactly 255. The
> relevant ChangeLog entry that Ben dug out was:
>
> | 2000-04-30 Andreas Jaeger <aj@suse.de>
> |
> | * posix/bits/posix1_lim.h (_POSIX_PATH_MAX): Increase to 256 in
> | accordance with Austin Draft.
>
> which seems to indicate that this has been done in order to conform to
> an upcoming version of the standard, which isn't what the above patch
> says. I'm somewhat mystified as to why such a change would be made,
> though.
History:
The original POSIX spec (1003.1-1990) indicated that PATH_MAX did not
include the terminating NULL, and that _POSIX_PATH_MAX was 255. At the
time that XPG4 (the first widely-adopted XPG spec) was created, the
draft 1003.1a amendment made _POSIX_PATH_MAX be 256, a size which was
more in line with some existing industry practice. XPG4, after some
argument, allowed either size for the _POSIX_PATH_MAX variable. Future
Open Group specs (SUS v1 and v2) also allow both.
POSIX 1003.1-1996 did not increase this to 256, since 1003.1a was not
approved yet. The next revision of 1003.1 (the Austin Group project)
will incorporate 1003.1a, making _POSIX_PATH_MAX officially and finally
256.
--
Mark S. Brown bmark@us.ibm.com
Senior Technical Staff Member 512.838.3926 T/L678.3926
IBM RS/6000 AIX System Architecture Mark Brown/Austin/IBM
IBM Corporation, Austin, Texas