[Fontconfig] How necessary is 'scandir'?

[Akira TAGOH]

the background is, we've added -Werror to address the build issue on older
glibc against posix_fadvise()[1]. the error stopped on scandir() check was
a side-effect coming from it. maybe it was wrong way. though I had no idea
to address it other than that way.

let me take a look again and think more.

[1] https://bugs.freedesktop.org/show_bug.cgi?id=52573

On Sun, Feb 15, 2015 at 10:01 PM, Raimund Steger <rs at mytum.de> wrote:

> On 02/12/15 03:59, Akira TAGOH wrote:
>
>> If the own scandir works on the platforms where don't have POSIX version
>> of scandir, we could drop that check. if anyone confirm, that would be
>> appreciated.
>>
>
> The question is, for what cases would we need our own scandir. Because:
>
> (1) On Win32, FcDirChecksum isn't used (we use FcStat/GetFileAttributesEx
> only)
>
> (2) On all platforms we supported before 38ab7ab2fbd83c0c62e4b78302b5fe89da0cb79e
> (where the configure check was introduced), scandir *is* available. Either
> the POSIX one (in the sense of [1]) which uses dirent comparators or the
> one that uses void* [2].
>
> Because of that, we wouldn't need to specifically test for [1] and could
> just assume it's there, avoiding clashes with UNIX compilers that can't
> execute our test because of -Werror.
>
> Now what about platforms where there is indeed neither GetFileAttributesEx
> nor any version of scandir? I admit that these were probably supported
> before 0ac6c98294d666762960824d39329459b22b48b7 (
> https://bugs.freedesktop.org/show_bug.cgi?id=25535) and aren't now. If we
> wanted to support those, then yes, we would need to check for both scandir
> versions, although the check for the POSIX variant could be a simple
> fallback that doesn't need -Werror. And even then, we could probably simply
> ignore the result of FcIsFsMtimeBroken as the change addressed FAT file
> systems on UNIX/Linux only. I mean, the set of UNIX/Linux systems that
> don't have scandir and at the same time use a font directory on FAT is
> probably rather small...
>
> Raimund
>
>
> [1] http://pubs.opengroup.org/onlinepubs/9699919799/
> functions/alphasort.html
> [2] http://netbsd.gw.com/cgi-bin/man-cgi?scandir+3+NetBSD-current
>
>
>
>
>
>
>  On Thu, Feb 12, 2015 at 7:55 AM, Raimund Steger <rs at mytum.de
>> <mailto:rs at mytum.de>> wrote:
>>
>>     On 02/11/15 19:40, Michael Felt wrote:
>>
>>         Yes, xlC, and I was hoping it was just a stray gcc flag.
>>
>>
>>     If that's indeed the reason, you can:
>>
>>     (0) To confirm whether it is, replace WERROR_CFLAGS="-Werror" with
>>     WERROR_CFLAGS="" in configure.ac <http://configure.ac>, run
>>     autoconf, configure etc.
>>
>>     If that works:
>>
>>     (1) find an equivalent flag for XL C and create a patch, just like
>>     the one for SunPRO [1]. If I understand the documentation right [2],
>>     this could be "-qmaxerr=1:w" (increase the number 1 if some
>>     'statement not reached' stuff gets in your way), but it's difficult
>>     to say without an actual installation to test.
>>
>>     (2) create a patch similar to (1), but set WERROR_CFLAGS="" or
>>     disable the scandir check altogether when compiling with XL C. I
>>     believe before [3] there wasn't even a scandir check, and the change
>>     was only to silence warnings on NetBSD if I read the commit right. I
>>     doubt you will have any problem on AIX.
>>
>>     Actually I'm still somewhat unhappy that configure wants to
>>     acknowledge the POSIX version of scandir specially when only
>>     recognizing the NetBSD version would probably have sufficed ...
>>     would have saved us a lot of if's, maybe even the one for $os_win32.
>>
>>     But I'll shut my mouth again.
>>
>>     -Raimund
>>
>>
>>
>>     [1]
>>     http://cgit.freedesktop.org/__fontconfig/commit/?id=__
>> 694368667a15341ea30b37a36e9540__e6b1492680
>>     <http://cgit.freedesktop.org/fontconfig/commit/?id=
>> 694368667a15341ea30b37a36e9540e6b1492680>
>>     [2]
>>     http://www-01.ibm.com/support/__knowledgecenter/SSGH2K_13.1.
>> 0/__com.ibm.xlc131.aix.doc/__compiler_ref/opt_maxerr.html?__lang=en
>>     <http://www-01.ibm.com/support/knowledgecenter/
>> SSGH2K_13.1.0/com.ibm.xlc131.aix.doc/compiler_ref/opt_maxerr.html?lang=en
>> >
>>     [3]
>>     http://cgit.freedesktop.org/__fontconfig/commit/?id=__
>> 38ab7ab2fbd83c0c62e4b78302b5fe__89da0cb79e
>>     <http://cgit.freedesktop.org/fontconfig/commit/?id=
>> 38ab7ab2fbd83c0c62e4b78302b5fe89da0cb79e>
>>
>>
>>
>>
>>
>>
>> --
>> Akira TAGOH
>>
>
>
> --
> Worringer Str 31 Duesseldorf 40211 DE  home: <rs at mytum.de>
> +49-179-2981632 icq 16845346           work: <rs at interface-ag.de>
>



-- 
Akira TAGOH
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