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image/gif: check rejection of this gif #3565

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gopherbot opened this issue Apr 24, 2012 · 10 comments
Closed

image/gif: check rejection of this gif #3565

gopherbot opened this issue Apr 24, 2012 · 10 comments

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@gopherbot
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@gopherbot gopherbot commented Apr 24, 2012

by kballard:

The attached GIF is rendered successfully by both Chrome and Firefox. It probably has
some sort of corruption though, because Safari and Preview render it as corrupt (though
it still does render). GraphicConverter also renders it as corrupt, though in a
different fashion.

However, Go doesn't render it at all. It just returns the error "lzw: invalid
code".

Mac OS X 10.7.3, go version go1.

Attachments:

  1. GGUVZ.gif (9997027 bytes)
@rsc
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@rsc rsc commented Apr 25, 2012

Comment 1:

This could be a feature.  Now that I've looked at it in Chrome, I can't unsee that gif.

Labels changed: added priority-later, removed priority-triage.

Owner changed to @nigeltao.

Status changed to Accepted.

@gopherbot
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@gopherbot gopherbot commented Apr 26, 2012

Comment 3 by kballard:

For the record, Safari/Preview on Mountain Lion render this GIF correctly now as well.
@rsc
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@rsc rsc commented Sep 12, 2012

Comment 4:

Labels changed: added go1.1maybe.

@rsc
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@rsc rsc commented Mar 12, 2013

Comment 5:

[The time for maybe has passed.]

Labels changed: removed go1.1maybe.

@gopherbot
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@gopherbot gopherbot commented Mar 13, 2013

Comment 6 by jeff.allen:

I looked into this a bit. I found that when the invalid code is found:
code 639
litwidth 8
width 12
clear 256
eof 257
hi 90
ovf 4096
last 98
Because 639 < 90 (d.hi), it fails. I'll trace through another gif decoder and try to
see what they do when receiving a code like this.
@gopherbot
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@gopherbot gopherbot commented Mar 13, 2013

Comment 7 by jeff.allen:

Another GIF that causes Go problems:
https://bug525326.bugzilla.mozilla.org/attachment.cgi?id=409291
Don't know if it is the same problem yet, if not, I'll file a new bug.
@gopherbot
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@gopherbot gopherbot commented Mar 13, 2013

Comment 8 by jeff.allen:

I suspect this code in Webkit shows the way to making Go's gif decoder more lenient:
http://trac.webkit.org/browser/trunk/Source/WebCore/platform/image-decoders/gif/GIFImageReader.cpp?rev=131831#L322
More later.
@gopherbot
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@gopherbot gopherbot commented Mar 14, 2013

Comment 9 by jeff.allen:

A fix for this would involve making compress/lzw tolerant of incorrectly encoded
streams. This seems like a bad idea in general. So a correct fix would need to add to
the API of compress/lzw a boolean for "tolerate errors?".
An API change to compress/lzw before Go 1.1 is not going to happen, so I think punting
on this is the right call.
The image in comment #7 is something else (issue #5050).
@gopherbot
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@gopherbot gopherbot commented Jul 4, 2013

Comment 10 by jeff.allen:

I think closing this as Won't Fix would be a good idea. Thanks.
@nigeltao
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@nigeltao nigeltao commented Jul 5, 2013

Comment 11:

Status changed to WorkingAsIntended.

@golang golang locked and limited conversation to collaborators Jun 24, 2016
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