1731003 - RemoteAccessible shouldn't try to call methods on a COM proxy if the cache is enabled

Status: RESOLVED FIXED

(Core :: Disability Access APIs, defect)

Description

[James Teh [:Jamie]]

On Windows, the cache is all or nothing. When it's disabled, we get COM proxies from the content process and everything uses those. When the cache is enabled, we don't get COM proxies from the content process and we can only use the cache.

1. Currently, methods (Name, Description, etc.) in RemoteAccessible fall back to the COM proxy if mCachedFields is null.
2. But even when the cache is enabled, mCachedFields can be null if there were no cache-worthy fields for this Accessible.
3. In that case, we'll try to fall back to the COM proxy, which will end up returning the MsaaAccessible from our process.
4. We'll then call the COM method on that MsaaAccessible; get_accName, get_accDescription, etc.
5. Because the cache is enabled, that method will call RemoteAccessible::Name, RemoteAccessible::Description, etc., taking us back to point 1.
6. Infinite recursion ensues, culminating in a spectacular crash.

Instead, these RemoteAccessible methods should check whether the cache is enabled. If it is, they should use the RemoteAccessibleBase method (regardless of mCachedFields). If not, they should always use the COM proxy.

Comment 1

[James Teh [:Jamie]]

Attachment: Bug 1731003: RemoteAccessible: Don't try to use the COM proxy at all if the cache is enabled, even if mCachedFields is null.

If the cache is enabled, we don't have COM proxies from the content process.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c6968bdb0338
RemoteAccessible: Don't try to use the COM proxy at all if the cache is enabled, even if mCachedFields is null. r=eeejay

Comment 3

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/c6968bdb0338