There's no reason to do this any different than we do for XOWs and such. The
only thing this might conceivably support would be certain chrome XPWNs-as-COWs.
But that would require that they forced a parent in precreate without being
flagged as DOM objects in classinfo. And it's not clear why we'd want to support
that. And we're generally moving away from COWs anyway.
The naming scheme for Xray typedefs is the concatenation of the tuple:
({SC,}, {Security,Permissive}, Xray, {XPCWN,DOM}). This is admittedly a bit
much, but I think it's still better than explicitly doing the "typdef Foo Xray"
everywhere. Moreover, once the new DOM bindings are done, the last component
in the tuple will go away.
Switch from using the interface objects from the Xrays compartment to wrapping
interface objects and interface prototype objects in Xrays. Make dom binding
Xrays deal with both instance objects and interface and interface prototype
objects.
This change means we no longer have to keep around a set of XPConnect compartments.
We keep the compartment private around for non-xpconnecty stuff like about:memory
instrumentation that needs to happen on non-xpconnect compartments.
We don't currently have a good way of selecting the traits used by a given Xray
wrapper. This lets us do that.
Note: We add a call to js::UnwrapObject to GetXrayType while hoisting it. When
it was used only in WrapperFactory, this was unnecessary, because |obj| was
always unwrapped. But for our new purposes, it might not be. Aside from that,
there are no changes to the function.
With this patch, all holders are created lazily. There are two common accessors,
getHolder() and ensureHolder(). The former returns null if no holder exists, the
latter lazily creates the holder if it doesn't exist. It does this by calling into
a virtual trap on XrayTraits, which lets the appropriate Xray type do its thing.
We currently set this for system globals and anything whose parent
chain leads to a system global. Maybe this was relevant before, but
with CPG this is just equivalent to asking whether the object is in
a system compartment. And the only place where we _check_ this bit
is immediately after checking for a system compartment, in
WrapperFactory. So AFAICT this can go away entirely.
We currently set this for system globals and anything whose parent
chain leads to a system global. Maybe this was relevant before, but
with CPG this is just equivalent to asking whether the object is in
a system compartment. And the only place where we _check_ this bit
is immediately after checking for a system compartment, in
WrapperFactory. So AFAICT this can go away entirely.
This can happen if chrome sets its proto to a content object from a different scope
than the one doing the wrapping. In this case, the prototype chain looks like this:
chromeobj => CCW(examplecom_obj) => CCW(examplecom_scope.Object.prototype)
When wrapping chromeobj for exampleorg_scope, things will look like this:
COW(chromeobj) => CCW(examplecom_obj) => CCW(examplecom_scope.Object.prototype)
Note that we don't remap the proto of CCW(examplecom_scope) to
exampleorg_scope.Object.prototype, because the proto remapping only happens when
the object we're wrapping is chrome. There's no reason it has to be this way, but
even if we changed it we still wouldn't get the nice remapped lookup behavior to
exampleorg_scope.Object.prototype, because the proxy handler for CCW(examplecom_obj)
isn't a ChromeObjectWrapper, and thus doesn't know how to to the prototype bouncing
correctly.
Anyway, I suspect this case isn't worth worrying about as long as we don't crash.
