icodec: correctly check avio_read return value

It can read less than the requested amount, in which case buf contains
uninitialized data, causing problems like segmentation faults later on.

Also make sure that image->size is positive, so that it can't match a
negative error code.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
(cherry picked from commit 89eb398c7fc4cb9a15e55bdf2ab6435b5332e377)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>

0 files changed, 0 insertions, 0 deletions