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

[Juan Francisco Cantero Hurtado]

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

>
>> 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
>