1160801 - Assertion failure: false (MOZ_ASSERT_UNREACHABLE: Unexpected DisposalMethod) @ mozilla::image::FrameAnimator::DoBlend

Status: RESOLVED FIXED

(Core :: Graphics: ImageLib, defect)

Description

[Bob Clary [:bc] (inactive)]

Attachment: Crash report

1. http://ohnotheydidnt.livejournal.com/?skip=30
2. Assertion failure: false (MOZ_ASSERT_UNREACHABLE: Unexpected DisposalMethod)

Nightly OSX, Linux, Windows 7

Comment 1

[Seth Fowler [:seth] [:s2h]]

Thanks for reporting this! This is potentially serious...

Comment 2

[Seth Fowler [:seth] [:s2h]]

Attachment: Treat invalid GIF disposal methods as DisposalMethod::NOT_SPECIFIED

The GIF89a spec defines four disposal methods (see page 16):

http://www.w3.org/Graphics/GIF/spec-gif89a.txt

Disposal methods 0, 1, 2, and 3 are used. 4, 5, 6, and 7 are left undefined by
the spec. We treat 4 as 3, but we currently have no interpretation for 5, 6, or
7. There's no valid value in the DisposalMethod enumeration for these undefined
disposal methods, and that's what caused the assertion to fire.

This patch makes us treat methods 5, 6, and 7 as method 0
(DisposalMethod::NOT_SPECIFIED). This eliminates the assertion, and causes us to
render the GIF in question the same way that WebKit does.

I've also included regression tests, each of which tests correct handling for
one of the undefined disposal methods.

Comment 3

[Seth Fowler [:seth] [:s2h]]

Attachment: Treat invalid GIF disposal methods as DisposalMethod::NOT_SPECIFIED

Ack, left a print in the previous patch by mistake.

Comment 4

[Seth Fowler [:seth] [:s2h]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=1633bd39ba03

Comment 5

[Seth Fowler [:seth] [:s2h]]

Hmm, I can see this test becoming an intermittent orange. Unfortunately I don't think delaytest.html is reliable. =\

Perhaps I should just make these crashtests...

Comment 6

[Seth Fowler [:seth] [:s2h]]

Attachment: Treat invalid GIF disposal methods as DisposalMethod::NOT_SPECIFIED

Same C++ code, but switched the tests to just be crashtests.

Comment 7

[Seth Fowler [:seth] [:s2h]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=d62fe19e0726

Comment 8

[Seth Fowler [:seth] [:s2h]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/d15063ca7a45

Comment 9

[Seth Fowler [:seth] [:s2h]]

Thanks for the review! I went ahead and pushed since all seems well on try.

Comment 10

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/d15063ca7a45