973321 - "Assertion failure: border.Side(s) >= 0"

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Jesse Ruderman]

Attachment: testcase

Assertion failure: border.Side(s) >= 0, at layout/base/nsCSSRendering.cpp:3136

This assertion was added in bug 827227.

Comment 1

[Jesse Ruderman]

Attachment: stack

Comment 2

[William Chen [:wchen]]

Attachment: Prevent int overflow in border image width calculation.

This assertion is caused by NS_lround returning a negative value for very large double values.

value = coord.GetFactorValue() * borderWidths.Side(s);
...
border.Side(s) = NS_lround(value);
MOZ_ASSERT(border.Side(s) >= 0);

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 8377841 [details] [diff] [review]
Prevent int overflow in border image width calculation.

>-    border.Side(s) = NS_lround(value);
>+    // NSToCoordRoundWithClamp rounds towards infinity, but that's OK
>+    // because we expect value to be non-negative.
>+    MOZ_ASSERT(value >= 0);
>+    border.Side(s) = NSToCoordRoundWithClamp(value);

I tend to think the comment isn't needed, because NSToCoordRound* are what we use for coordinate rounding in layout; using something else (such as lround) should require an explanation.

r=dbaron, although I'm a little skeptical about the use of fatal assertions here

Comment 4

[William Chen [:wchen]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/dccc80373461

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/dccc80373461