1440949 - Allow plain JS objects to require addon interposition

Status: RESOLVED FIXED

(Firefox :: Extension Compatibility, enhancement)

Description

[Brian Grinstead [:bgrins]]

For Bug 1392352, I'm planning to turn gBrowser into a plain JS object instead of a DOM node. So in order to apply TabBrowserElementInterposition we need to provide a way for the object to run interpositions as suggested in https://bugzilla.mozilla.org/show_bug.cgi?id=1392352#c77.

Comment 1

[Brian Grinstead [:bgrins]]

Attachment: Bug 1440949 - Allow plain JS objects to request addon interposition;

This is needed to allow interposition for gBrowser, which will change from a DOM node
into a plain JS object in Bug 1392352.  An object can set the `requiresAddonInterpositions`
property to enable this feature.

Review commit: https://reviewboard.mozilla.org/r/222980/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/222980/

Comment 2

[Kris Maglione [:kmag]]

Comment on attachment 8953781 [details]
Bug 1440949 - Allow plain JS objects to request addon interposition;

https://reviewboard.mozilla.org/r/222980/#review228898

Close. Just a couple of minor issues.

::: js/xpconnect/wrappers/AddonWrapper.cpp:45
(Diff revision 1)
>  
>  bool
> +RequiresInterpositions(JSContext* cx, HandleObject target)
> +{
> +    bool requiresAddonInterpositions;
> +    RootedObject unwrapped(cx, UncheckedUnwrap(target));

This is not especially cheap. Please just pass in the unwrapped object we already have rather than unwrapping again.

::: js/xpconnect/wrappers/AddonWrapper.cpp:48
(Diff revision 1)
> +{
> +    bool requiresAddonInterpositions;
> +    RootedObject unwrapped(cx, UncheckedUnwrap(target));
> +    JSAutoCompartment ac(cx, unwrapped);
> +
> +    if (!JS_HasOwnProperty(cx, unwrapped, "requiresAddonInterpositions", &requiresAddonInterpositions)) {

It probably doesn't matter much, but we should also check whether the property value is `true` rather than just that it exists. It would be strange/confusing to have `requiresAddonInterpositions: false` turn interpositions on.

Also, if this fails, we need to do `JS_ClearPendingException(cx)`, or we'll run into problems.

Comment 3

[Brian Grinstead [:bgrins]]

Comment on attachment 8953781 [details]
Bug 1440949 - Allow plain JS objects to request addon interposition;

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/222980/diff/1-2/

Comment 4

[Brian Grinstead [:bgrins]]

Thanks for the review, uploaded a new version. I'm not sure if the truthy testing is correct - I pulled this from some other code accessing JS_GetOwnPropertyDescriptor.

Comment 5

[Kris Maglione [:kmag]]

Comment on attachment 8953781 [details]
Bug 1440949 - Allow plain JS objects to request addon interposition;

https://reviewboard.mozilla.org/r/222980/#review229378

::: js/xpconnect/wrappers/AddonWrapper.cpp:42
(Diff revision 2)
>          return;
>      JS_ReportErrorUTF8(cx, msg, bytes.ptr());
>  }
>  
>  bool
> +RequiresInterpositions(JSContext* cx, RootedObject* unwrapped)

s/RootedObject\*/HandleObject/

::: js/xpconnect/wrappers/AddonWrapper.cpp:44
(Diff revision 2)
>  }
>  
>  bool
> +RequiresInterpositions(JSContext* cx, RootedObject* unwrapped)
> +{
> +    JS::Rooted<JS::PropertyDescriptor> desc(cx);

`Rooted<PropertyDescriptor>`

::: js/xpconnect/wrappers/AddonWrapper.cpp:52
(Diff revision 2)
> +    if (!JS_GetOwnPropertyDescriptor(cx, *unwrapped, "requiresAddonInterpositions", &desc)) {
> +        JS_ClearPendingException(cx);
> +        return false;
> +    }
> +
> +    return desc.object() && desc.value().isTrue();

s/object/hasValue/

Comment 6

[Brian Grinstead [:bgrins]]

Comment on attachment 8953781 [details]
Bug 1440949 - Allow plain JS objects to request addon interposition;

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/222980/diff/2-3/

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/eacdc0b781e2
Allow plain JS objects to request addon interposition;r=kmag

Comment 8

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/eacdc0b781e2