[Pixman] [PATCH] glyphs: Check the return code from _pixman_implementation_lookup_composite()

[Juan Francisco Cantero Hurtado]

On 01/13/13 02:35, Juan Francisco Cantero Hurtado wrote:
> On 01/12/13 12:40, Søren Sandmann wrote:
>> Chris Wilson <chris at chris-wilson.co.uk>
>> writes:
>>
>>> We can not rely on the value of func after
>>> _pixman_implementation_lookup_composite() as the sole means of
>>> identifying a bogus implementation as it is left uninitialized on the
>>> error path. Instead we need to check the explicit return value.
>>
>> _pixman_implementation_lookup_composite() is not supposed to fail ever
>> because eventually it will find general_composite_rectangle() which can
>> always be used. When it does fail, it is almost always because something
>> is broken with TLS support so that the fast path cache is messed up.
>
> OpenBSD and gcc 4.2 (the default compiler) don't support thread local
> storage.
>
>>
>> Juan, can you send config.log from when you compiled pixman, and also
>> let us know what the line
>>
>>      #define TLS ...
>>
>> in config.h says?
>
> /* The compiler supported TLS storage class */
> /* #undef TLS */
>
>
> http://juanfra.info/bugs-y-listas/cairo-racket-201301/config.log
>
> http://juanfra.info/bugs-y-listas/cairo-racket-201301/config.h

And here is the original thread in the cairo list:

http://thread.gmane.org/gmane.comp.lib.cairo/23503/focus=23509

>
>>
>>> Reported-by: Juan Francisco Cantero Hurtado
>>> <iam at juanfra.info>
>>> Signed-off-by: Chris Wilson
>>> <chris at chris-wilson.co.uk>
>>> ---
>>>   pixman/pixman-glyph.c |   30 +++++++++++++-----------------
>>>   1 file changed, 13 insertions(+), 17 deletions(-)
>>
>> Regarding the patch, if we want to make this more robust, I think a
>> better course of action would be to set func to NULL and call
>> _pixman_log_error() with some suitable message about TLS before
>> returning FALSE in _pixman_implementation_lookup_composite().
>>
>> Or alternatively, make it so that
>> _pixman_implementation_lookup_composite() definitely can't fall by
>> returning some dummy compositing function.
>>
>>
>> Soren
>>