1487159 - WebExtension API: downloads.download regression on Firefox developer edition

Status: RESOLVED INVALID

(Firefox :: Untriaged, defect)

Description

[Gildas Lormeau]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0
Build ID: 20180824192747

Steps to reproduce:

1 - Install SingleFile extension on Firefox developer edition from here: https://addons.mozilla.org/fr/firefox/addon/single-file
2 - Go to https://bugzilla.mozilla.org/ and click on the extension button



Actual results:

The download fails. If you uncheck "Misc > save pages in background" in the options page of SingleFile, the download does not fail. Unchecking this option allows downloading the page via a hidden link in the page itself instead of relying on the downloads.download API. This issue also exists on Firefox beta on Android. That's why you can uncheck the option on it.


Expected results:

The page should have been saved like on previous versions of Firefox

Comment 1

[Gildas Lormeau]

(In reply to Gildas Lormeau from comment #0)
> User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0)
> Gecko/20100101 Firefox/63.0
> Build ID: 20180824192747
> 
> Steps to reproduce:
> 
> 1 - Install SingleFile extension on Firefox developer edition from here:
> https://addons.mozilla.org/fr/firefox/addon/single-file
> 2 - Go to https://bugzilla.mozilla.org/ and click on the extension button
> 
> 
> 
> Actual results:
> 
> The download fails. If you uncheck "Misc > save pages in background" in the
> options page of SingleFile, the download does not fail. Unchecking this
> option allows downloading the page via a hidden link in the page itself
> instead of relying on the downloads.download API. This issue also exists on
> Firefox beta on Android. That's why you can uncheck the option on it.
> 
> 
> Expected results:
> 
> The page should have been saved like on previous versions of Firefox

Sorry, I meant "That's why you *cannot* uncheck the option on it."

Comment 2

[Gildas Lormeau]

I found the cause of the issue. SingleFile uses a Blob URI to download a page content. The problem is that the Blob URI is revoked with URL.revokeObjectURL just after browser.downloads.download is called. In Firefox 62 and Chrome, it is not a problem. Since Firefox 63, it looks like URL.revokeObjectURL must be called later. The issue is fixed by calling it into the browser.downloads.onChanged handler when the download state is complete.