745272 - nsAudioAvailableEventManager.cpp:195:35: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Daniel Holbert [:dholbert]]

Filing bug on this build warning...
{
../../../mozilla/content/media/nsAudioAvailableEventManager.cpp: In member function ‘void nsAudioAvailableEventManager::QueueWrittenAudioData(AudioDataValue*, PRUint32, PRUint64)’:
../../../mozilla/content/media/nsAudioAvailableEventManager.cpp:195:35: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
}

...for this chunk of code...

> 149   PRUint32 audioDataLength = aAudioDataLength;
[...]
> 153   while (signalBufferTail <= audioDataLength) {
[...]
> 167     audioData += signalBufferTail;
> 168     audioDataLength -= signalBufferTail;
[...]
> 195     NS_ASSERTION(audioDataLength >= 0, "Past new signal data length.");
[...]
> 209   }

...which was added in bug 490705.

Note that audioDataLength is unsigned, so it's >= 0 by definition.

If we actually want to assert that it's not going to wrap around, we should assert _just before_ line 168 that we're not about to subtract a value larger than audioDataLength.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: fix

Comment 2

[Daniel Holbert [:dholbert]]

(this is a build warning from g++ 4.6.3, FWIW)

Comment 3

[David Humphrey (:humph)]

Comment on attachment 614866 [details] [diff] [review]
fix

Review of attachment 614866 [details] [diff] [review]:
-----------------------------------------------------------------

This looks good, thanks for catching it.  Since I'm not an owner/peer, I'm going to ask cpearce to look at this.

Comment 4

[Chris Pearce [:cpearce (Not reading bugmail)]]

Comment on attachment 614866 [details] [diff] [review]
fix

Review of attachment 614866 [details] [diff] [review]:
-----------------------------------------------------------------

Looks good.

Comment 5

[Daniel Holbert [:dholbert]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/cfcd178b2f5f

Comment 6

[Marco Bonardo [:mak]]

https://hg.mozilla.org/mozilla-central/rev/cfcd178b2f5f