* bug#8238: possibly uninitialized variable in gif_load
@ 2011-03-13 7:17 Paul Eggert
2011-03-13 10:27 ` Julien Danjou
0 siblings, 1 reply; 3+ messages in thread
From: Paul Eggert @ 2011-03-13 7:17 UTC (permalink / raw)
To: 8238; +Cc: Julien Danjou
I found this problem by code inspection.
The following code in the Emacs trunk src/image.c's gif_load
function is suspicious, because it uses a variable transparent_p
that appears to be uninitialized in some cases:
boolean transparent_p;
...
for (i = 0; i < gif->SavedImages[ino].ExtensionBlockCount; i++)
if ((gif->SavedImages[ino].ExtensionBlocks[i].Function
== GIF_LOCAL_DESCRIPTOR_EXTENSION)
&& gif->SavedImages[ino].ExtensionBlocks[i].ByteCount == 4
/* Transparency enabled? */
&& gif->SavedImages[ino].ExtensionBlocks[i].Bytes[0] & 1)
{
transparent_p = 1;
...
}
...
if (gif_color_map)
for (i = 0; i < gif_color_map->ColorCount; ++i)
{
if (transparent_p && transparency_color_index == i)
The code never sets transparent_p to any value other than 1,
but sometimes transparent_p appears to be uninitialized.
I'm filing a bug report so that someone who is more expert in this
code can take a look at it. In the meantime, I plan to work around
the problem by initializing the variable to 0.
I'm CC'ing this to Julien Danjou, who committed the code in question.
^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#8238: possibly uninitialized variable in gif_load
2011-03-13 7:17 bug#8238: possibly uninitialized variable in gif_load Paul Eggert
@ 2011-03-13 10:27 ` Julien Danjou
2011-03-13 17:43 ` Paul Eggert
0 siblings, 1 reply; 3+ messages in thread
From: Julien Danjou @ 2011-03-13 10:27 UTC (permalink / raw)
To: Paul Eggert; +Cc: bug-gnu-emacs
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On Sun, Mar 13 2011, Paul Eggert wrote:
> I'm filing a bug report so that someone who is more expert in this
> code can take a look at it. In the meantime, I plan to work around
> the problem by initializing the variable to 0.
Yeah, this should be the good fix AFAICS.
--
Julien Danjou
❱ http://julien.danjou.info
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^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#8238: possibly uninitialized variable in gif_load
2011-03-13 10:27 ` Julien Danjou
@ 2011-03-13 17:43 ` Paul Eggert
0 siblings, 0 replies; 3+ messages in thread
From: Paul Eggert @ 2011-03-13 17:43 UTC (permalink / raw)
To: Julien Danjou; +Cc: 8238-done
On 03/13/2011 03:27 AM, Julien Danjou wrote:
> Yeah, this should be the good fix AFAICS.
OK, thanks, I committed that as part of the merge to the
trunk in bzr 103644.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-03-13 7:17 bug#8238: possibly uninitialized variable in gif_load Paul Eggert
2011-03-13 10:27 ` Julien Danjou
2011-03-13 17:43 ` Paul Eggert
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