[Fontconfig] Re: Yet another easy to reproduce crash in fontconfig

[Mike FABIAN]

Mike FABIAN <mfabian at suse.de> さんは書きました:

> mfabian at magellan:~$ sudo rm /var/cache/fontconfig/*cache*
> mfabian at magellan:~$ rm .fonts.cache-2 
> mfabian at magellan:~$ fc-match sans
> arial.ttf: "Arial" "Regular"
> mfabian at magellan:~$ touch .fonts.conf
> mfabian at magellan:~$ fc-match sans
> セグメンテーション違反です (core dumped)
> mfabian at magellan:~$
>
> (gdb) bt
> #0  0x00002aaaab12c420 in strlen () from /lib64/libc.so.6
> #1  0x00002aaaaabd7075 in FcGlobalCacheReadDir () from /usr/lib64/libfontconfig.so.1

The attached patch seems to fix the problem for me.

Without that patch, directories which are subdirectories of
directories listed in the config files (/etc/fonts/fonts.conf etc)
were added too late to the list of font directories in "FcConfig
*config". For example, when FcDirScanConfig() was called with the
argument "/usr/share/fonts/bdf" the list of font directories in
config->fontDirs->strs still contained only the higher level
directory "/usr/share/fonts" because only that was listed in the
config files, not the "bdf" subdirectory.

FcDirScanConfig() then calls FcGlobalCacheReadDir() before
adding the subdirectory to the list, FcGlobalCacheReadDir()
calls FcConfigNormalizeFontDir(dir) which returns 0 because the directory
is not yet in the list and then it crashes in strlen(dir) of course.

To fix this, I moved the call to FcConfigAddFontDir (config, dir)
upwards in FcDirScanConfig() to add the directory *before*
FcGlobalCacheReadDir() is called.

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-- 
Mike FABIAN   <mfabian at suse.de>   http://www.suse.de/~mfabian
睡眠不足はいい仕事の敵だ。