[poppler] A memory leak in GlobalParams::~GlobalParams()?

[mpsuzuki at hiroshima-u.ac.jp]

Hi,

On Wed, 20 Jan 2010 21:11:09 +0000
Albert Astals Cid <aacid at kde.org> wrote:
>A Divendres, 15 de gener de 2010, mpsuzuki at hiroshima-u.ac.jp va escriure:
>> I had ever reported a possibility of memory leak in
>> CairoFreeTypeFont::create(), then, I found another
>> possibility of memory leak in GlobalParams::~GlobalParams().
>
>I am not sure of that, FcConfigGetCurrent not always creates an object,

Oh, I'm sorry for missing the possibility that other
part of software has already initialized "_fcConfig"
and poppler just refers it via FcConfigGetCurrent().
Thank you very much.

>as it can return you an already existing object, so deleting
>on exit doesn't really seem wise as you could be removing
>the object from underneath the feet of whoever else created
>it (Qt, Pango, Cairo, etc)

I see. Checking fontconfig source, I found FcConfig
has a reference counter, and FcConfigDestroy() checks
it so that the client can prevent freeing the object
in use.

fontconfig/src/fccfg.c

    233 void
    234 FcConfigDestroy (FcConfig *config)
    235 {
    236     FcSetName   set;
    237     FcExprPage  *page;
    238 
    239     if (--config->ref > 0)
    240         return;
    241 
    242     if (config == _fcConfig)
    243         _fcConfig = 0;
    ...

However, FcConfigGetCurrent() does not increment the
reference counter when it returns existing object.
I will ask the correct procedure how to obtain FcConfig
and free it in fontconfig mail list.

>So as you're supposed to only create one GlobalParams per
>execution i don't think it's a problematic leak and will
>vote for leaving it as it is.

Do you think it's a leak but not so serious to apply
my wrong patch?  I understood my patch was wrong and
must be reworked. Anyway, I attached valgrind logs of
pdftotext, original one (LOG-20100121a.txt) and patched
one (LOG-20100121b.txt).

Regards,
mpsuzuki
-------------- next part --------------
A non-text attachment was scrubbed...
Name: LOG-20100121a.txt.bz2
Type: application/octet-stream
Size: 1319 bytes
Desc: not available
Url : http://lists.freedesktop.org/archives/poppler/attachments/20100121/985cb0e2/attachment-0002.obj 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: LOG-20100121b.txt.bz2
Type: application/octet-stream
Size: 619 bytes
Desc: not available
Url : http://lists.freedesktop.org/archives/poppler/attachments/20100121/985cb0e2/attachment-0003.obj