1265317 - ”Unable to parse JSON data for extension storage” error for a webextension installation

Status: VERIFIED FIXED

(WebExtensions :: Untriaged, defect)

Description

[Vasilica Tamas, QA [:vtamas]]

[Note]
This is a follow-up bug for Bug 1197475

[Affected versions]:
Firefox 48.0a1 (2016-04-17)
Firefox 46.0b11 
Firefox 45.0.2

[Affected platforms]:
Windows 10 64-bit
Ubuntu 14.04 32-bit
Mac OS X 10.11

[Steps to reproduce]:
1.Launch Firefox with clean profile.
2.Create the xpinstall.signatures.dev-root pref in about:config and set it to true.
3.Install the following webextension:  https://addons.allizom.org/en-US/firefox/addon/testwebextension/?src=ss
4.Check the Browser Console.

[Expected Results]:
There are no errors thrown in Browser Console.

[Actual Results]:
The following JS error appears after installing the webextension: Unable to parse JSON data for extension storage. ExtensionStorage.jsm:49:0

[Additional notes]:
- I am marking Firefox 47.0a2 (2016-04-17) as unaffected because the webextension cannot be installed on this Firefox version.
- I was able to reproduce this issue down to Firefox 42.

Comment 1

[Kris Maglione [:kmag]]

I think this is a harmless error that just happens because we don't have a special case to handle when the file doesn't yet exist:

https://dxr.mozilla.org/mozilla-central/source/toolkit/components/extensions/ExtensionStorage.jsm#103

So we just need to check if OS.File.read throws an error because the file doesn't exist, and if so, treat it as success:

https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/OSFile.jsm/OS.File_for_the_main_thread#OS.File.read()

Comment 2

[Vikram]

Hi,

I am new here, If this bug is still open I would like to work on this.
I tried to reproduce the scenario. What I did:
I am using Mozilla VM, I executed following steps:
1. Build the source code.
2. Run the Nightly version of firefox
3. Followed steps to reproduce and got the error as mentioned.

I want to debug more. I used console.log() to check the path variable that is being passed in OS.File.read() and flow but did not get any sccusses.

Looking for help to debug and fix this issue.

Comment 3

[Vikram]

Also, As I am new I do not have much idea what code is done. It would be great if you could give some pointers.

Comment 4

[Kris Maglione [:kmag]]

`console.log` isn't available in this context. You can use Services.console.logStringMessage to log a message to the console, dump() to log a message to the standard output, or the browser debugger[1] if you need to debug browser code.


[1]: https://developer.mozilla.org/en-US/docs/Tools/Browser_Toolbox

Comment 5

[Martin Giger [:freaktechnik]]

Attachment: bug1265317-v1.patch

Fixes the error as suggested, by handling a missing file as success. After I applied this patch the error was gone.

Comment 6

[Kris Maglione [:kmag]]

Comment on attachment 8762899 [details] [diff] [review]
bug1265317-v1.patch

Review of attachment 8762899 [details] [diff] [review]:
-----------------------------------------------------------------

::: toolkit/components/extensions/ExtensionStorage.jsm
@@ +103,5 @@
>      let promise = OS.File.read(path);
>      promise = promise.then(array => {
>        return JSON.parse(decoder.decode(array));
> +    }, (error) => {
> +      if (error instanceof OS.File.Error && error.becauseNoSuchFile) {

We can add this check to the existing `.catch()` handler. And there's no need for the `instanceof OS.File.Error` check. Just checking the `becauseNoSuchFile` property is enough.

Comment 7

[Martin Giger [:freaktechnik]]

Attachment: bug1265317-v2.patch

Simplified the error handling as suggested.

Comment 8

[Kris Maglione [:kmag]]

Comment on attachment 8762907 [details] [diff] [review]
bug1265317-v2.patch

Review of attachment 8762907 [details] [diff] [review]:
-----------------------------------------------------------------

Looks good. Thanks!

Comment 9

[Martin Giger [:freaktechnik]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=4cec2c66eba0

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/369ea77ee0d9
Handle missing storage error as success. r=kmag

Comment 11

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/369ea77ee0d9

Comment 12

[Vasilica Tamas, QA [:vtamas]]

I was able to reproduce the initial issue on Firefox 48.0a1 (2016-04-18) under Windows 10 64-bit.

Verified as fixed on Firefox 50.01 (2016-06-26) under Windows 10 64-bit and Ubuntu 16.04 32-bit. The error is no longer thrown in Browser Console.