From e0d786d901a88c3b270be3f242279b0490fb091c Mon Sep 17 00:00:00 2001
From: Bobby Holley <bobbyholley@gmail.com>
Date: Wed, 4 Sep 2013 14:06:55 -0700
Subject: [PATCH] Bug 899367 - Add an API to opt out of default compartment
 objects. r=luke

We need this explicit API because otherwise the default compartment object will
get set implicitly during the first call to InitClasses.
---
 js/src/jsapi.h            |  6 +++++-
 js/src/jscntxt.h          |  5 ++++-
 js/src/jscntxtinlines.h   |  6 +++++-
 js/src/vm/SelfHosting.cpp | 12 +++++++++---
 4 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index d3229ed00f4..ba2bdf71cb7 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -1526,7 +1526,11 @@ JS_StringToVersion(const char *string);
 
 /* JS_BIT(10) is currently unused. */
 
-/* JS_BIT(11) is currently unused. */
+#define JSOPTION_NO_DEFAULT_COMPARTMENT_OBJECT JS_BIT(11)     /* This JSContext does not use a
+                                                                 default compartment object. Such
+                                                                 an object will not be set implicitly,
+                                                                 and attempts to get or set it will
+                                                                 assert. */
 
 #define JSOPTION_NO_SCRIPT_RVAL JS_BIT(12)      /* A promise to the compiler
                                                    that a null rval out-param
diff --git a/js/src/jscntxt.h b/js/src/jscntxt.h
index 9344245a6d7..9ef434396d9 100644
--- a/js/src/jscntxt.h
+++ b/js/src/jscntxt.h
@@ -449,7 +449,10 @@ struct JSContext : public js::ExclusiveContext,
   public:
     inline void setDefaultCompartmentObject(JSObject *obj);
     inline void setDefaultCompartmentObjectIfUnset(JSObject *obj);
-    JSObject *maybeDefaultCompartmentObject() const { return defaultCompartmentObject_; }
+    JSObject *maybeDefaultCompartmentObject() const {
+        JS_ASSERT(!hasOption(JSOPTION_NO_DEFAULT_COMPARTMENT_OBJECT));
+        return defaultCompartmentObject_;
+    }
 
     /* Wrap cx->exception for the current compartment. */
     void wrapPendingException();
diff --git a/js/src/jscntxtinlines.h b/js/src/jscntxtinlines.h
index c1c6cc3c97e..466cb1b4cfc 100644
--- a/js/src/jscntxtinlines.h
+++ b/js/src/jscntxtinlines.h
@@ -438,14 +438,18 @@ JSContext::setPendingException(js::Value v) {
 inline void
 JSContext::setDefaultCompartmentObject(JSObject *obj)
 {
+    JS_ASSERT(!hasOption(JSOPTION_NO_DEFAULT_COMPARTMENT_OBJECT));
     defaultCompartmentObject_ = obj;
 }
 
 inline void
 JSContext::setDefaultCompartmentObjectIfUnset(JSObject *obj)
 {
-    if (!defaultCompartmentObject_)
+    if (!hasOption(JSOPTION_NO_DEFAULT_COMPARTMENT_OBJECT) &&
+        !defaultCompartmentObject_)
+    {
         setDefaultCompartmentObject(obj);
+    }
 }
 
 inline void
diff --git a/js/src/vm/SelfHosting.cpp b/js/src/vm/SelfHosting.cpp
index a8590b2c9ad..2a6471fb1cd 100644
--- a/js/src/vm/SelfHosting.cpp
+++ b/js/src/vm/SelfHosting.cpp
@@ -682,12 +682,17 @@ bool
 JSRuntime::initSelfHosting(JSContext *cx)
 {
     JS_ASSERT(!selfHostingGlobal_);
-    RootedObject savedGlobal(cx, js::DefaultObjectForContextOrNull(cx));
+
+    bool receivesDefaultObject = !cx->hasOption(JSOPTION_NO_DEFAULT_COMPARTMENT_OBJECT);
+    RootedObject savedGlobal(cx, receivesDefaultObject
+                                 ? js::DefaultObjectForContextOrNull(cx)
+                                 : NULL);
     if (!(selfHostingGlobal_ = JS_NewGlobalObject(cx, &self_hosting_global_class,
                                                   NULL, JS::DontFireOnNewGlobalHook)))
         return false;
     JSAutoCompartment ac(cx, selfHostingGlobal_);
-    js::SetDefaultObjectForContext(cx, selfHostingGlobal_);
+    if (receivesDefaultObject)
+        js::SetDefaultObjectForContext(cx, selfHostingGlobal_);
     Rooted<GlobalObject*> shg(cx, &selfHostingGlobal_->as<GlobalObject>());
     /*
      * During initialization of standard classes for the self-hosting global,
@@ -756,7 +761,8 @@ JSRuntime::initSelfHosting(JSContext *cx)
         ok = Evaluate(cx, shg, options, src, srcLen, &rv);
     }
     JS_SetErrorReporter(cx, oldReporter);
-    js::SetDefaultObjectForContext(cx, savedGlobal);
+    if (receivesDefaultObject)
+        js::SetDefaultObjectForContext(cx, savedGlobal);
     return ok;
 }