1482215 - invisibleToDebugger should be a property of compartments, not realms

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement, P3)

Description

[Jim Blandy :jimb]

At the moment, the invisibleToDebugger flag is a property of individual realms, but this is very difficult to work with, as inter-realm edges are very common, meaning that Debugger operations that retrieve almost any value from the debuggee should be fallible.

Previously, the invisibleToDebugger flag was associated with compartments, so that only Debugger.Object.prototype.unwrap needed to be fallible in order to enforce it. We should move the flag back to compartments.

Fortunately, all uses of JS::RealmCreationOptions::setInvisibleToDebugger also request a fresh compartment, so this should not affect any users of the API.

Comment 1

[Jim Blandy :jimb]

jandem says that this should make it possible to remove the last use of JSObject::deprecatedRealm, found in Debugger. I've forgotten some of the details of this patch, but when I rebase it I'll make sure that removal makes sense, and include it in the patch.

Comment 2

[Jan de Mooij [:jandem]]

Please let me know if you can't get to this soon and I can do this.

Comment 3

[Jim Blandy :jimb]

I think I can get to this today.

Comment 4

[Jim Blandy :jimb]

Attachment: Bug 1482215: Make Debugger visibility per-Compartment, and ensure realms match their compartments. r?jorendorff

Comment 5

[Jim Blandy :jimb]

Try push:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=40a5949e94e139215137c54d9af73245f1cdfe6c

Comment 6

[Jim Blandy :jimb]

Attachment: Bug 1482215: Make Debugger visibility per-Compartment, and ensure realms match their compartments.

The final remaining code that assumes that every object is associated with a
global is in the Debugger API: Debugger.Object.prototype.unwrap consults the
unwrapped object's global to see whether it is about to reveal an object that it
must not.

This patch:

- adds an `invisibleToDebugger` flag to JS::Compartment, and sets it from the
  Realm options (since there is no API for creating compartments directly; only
  the act of creating a Realm can create a compartment to hold it);

- asserts that new realms added to a compartment have a compatible visibility; and

- has the shell primitive for creating realms throw an error in case of
  incompatibility, rather than crashing.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7e30c215f294
Make Debugger visibility per-Compartment, and ensure realms match their compartments. r=jorendorff

Comment 9

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/7e30c215f294