When ImageConversion is asked to scale or crop a corrupted image it
causes unexpected errors. I debugged this with an older version of
ImageConversion but looking at the latest code it seems that it may
still be there. If this has been fixed already please excuse me.
Some jpg images
have a small amount of corruption or extra bytes which most viewers
ignore. When one of these slightly corrupted images is converted
through GD, specifically through imagecreatefromjpeg(), it would
normally throw a warning and return false.
However in ez's ImageConversion code this error is suppressed. line 77 of
gd_base.php:
if ( !ezcBaseFeatures::hasFunction( $loadFunction ) || ( $handle =
@$loadFunction( $file ) ) === '' )
{
throw new ezcImageFileNotProcessableException( $file, "File could not be
opened using $loadFunction." );
}
(where $loadFunction is 'imagecreatefromjpeg' in this case)
So
no errors will be logged. $handle gets set to FALSE and since the code
is only checking if it's equal to '', it does not enter the if
statement. No exceptions are fired at this point, even though it has
failed, and 'resource' is set to FALSE. The next time
getReferenceData() is called looking for 'resource' it will fail with
an exception message like:
"No valid reference found for action. No resource found for the active
reference"
Which
is not a very useful error message since the cause is a corrupted jpeg.
I would suggest that the code be changed to something more like:
$handle = @$loadFunction( $file );
if ( !ezcBaseFeatures::hasFunction( $loadFunction ) || !$handle || $handle ===
'' )
{
throw new ezcImageFileNotProcessableException( $file, "File could not be
opened using $loadFunction." );
}
Or
it could even be more specific with additional 'if's. I've also noticed
that this seems to create left over tmp image files, so perhaps close()
is not being called in this error condition, but I haven't looked into that yet.
As a side note, this failure mode can also be obviated by using:
ini_set("gd.jpeg_ignore_warning", true);
Thanks. Let me know if you need a corrupted jpeg to test with.
-graham
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