From f56f915374f8b8de0746a1e68e0cf61ad74f2d14 Mon Sep 17 00:00:00 2001
From: Bobby Holley <bobbyholley@gmail.com>
Date: Sun, 20 Apr 2014 11:48:13 -0700
Subject: [PATCH] Bug 993772 - Introduce a singleton compilation scope.
 r=mrbkap

---
 js/xpconnect/src/XPCJSRuntime.cpp | 32 +++++++++++++++++++++++++++++--
 js/xpconnect/src/nsXPConnect.cpp  |  2 +-
 js/xpconnect/src/xpcprivate.h     |  4 +++-
 js/xpconnect/src/xpcpublic.h      |  8 ++++++++
 4 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/js/xpconnect/src/XPCJSRuntime.cpp b/js/xpconnect/src/XPCJSRuntime.cpp
index 8a6cff93596..770d336b3a0 100644
--- a/js/xpconnect/src/XPCJSRuntime.cpp
+++ b/js/xpconnect/src/XPCJSRuntime.cpp
@@ -587,6 +587,14 @@ GetJunkScopeGlobal()
     return GetNativeForGlobal(junkScope);
 }
 
+JSObject *
+GetCompilationScope()
+{
+    XPCJSRuntime *self = nsXPConnect::GetRuntimeInstance();
+    NS_ENSURE_TRUE(self, nullptr);
+    return self->GetCompilationScope();
+}
+
 JSObject *
 GetSafeJSContextGlobal()
 {
@@ -3045,6 +3053,7 @@ XPCJSRuntime::XPCJSRuntime(nsXPConnect* aXPConnect)
    mObjectHolderRoots(nullptr),
    mWatchdogManager(new WatchdogManager(MOZ_THIS_IN_INITIALIZER_LIST())),
    mJunkScope(MOZ_THIS_IN_INITIALIZER_LIST()->Runtime(), nullptr),
+   mCompilationScope(MOZ_THIS_IN_INITIALIZER_LIST()->Runtime(), nullptr),
    mAsyncSnowWhiteFreer(new AsyncFreeSnowWhite())
 {
     DOM_InitInterfaces();
@@ -3476,7 +3485,7 @@ XPCJSRuntime::GetJunkScope()
     if (!mJunkScope) {
         AutoSafeJSContext cx;
         SandboxOptions options;
-        options.sandboxName.AssignASCII("XPConnect Junk Compartment");
+        options.sandboxName.AssignLiteral("XPConnect Junk Compartment");
         RootedValue v(cx);
         nsresult rv = CreateSandboxObject(cx, &v, nsContentUtils::GetSystemPrincipal(), options);
         NS_ENSURE_SUCCESS(rv, nullptr);
@@ -3486,8 +3495,27 @@ XPCJSRuntime::GetJunkScope()
     return mJunkScope;
 }
 
+JSObject *
+XPCJSRuntime::GetCompilationScope()
+{
+    if (!mCompilationScope) {
+        AutoSafeJSContext cx;
+        SandboxOptions options;
+        options.sandboxName.AssignLiteral("XPConnect Compilation Compartment");
+        options.invisibleToDebugger = true;
+        RootedValue v(cx);
+        nsresult rv = CreateSandboxObject(cx, &v, /* principal = */ nullptr, options);
+        NS_ENSURE_SUCCESS(rv, nullptr);
+
+        mCompilationScope = js::UncheckedUnwrap(&v.toObject());
+    }
+    return mCompilationScope;
+}
+
+
 void
-XPCJSRuntime::DeleteJunkScope()
+XPCJSRuntime::DeleteSingletonScopes()
 {
     mJunkScope = nullptr;
+    mCompilationScope = nullptr;
 }
diff --git a/js/xpconnect/src/nsXPConnect.cpp b/js/xpconnect/src/nsXPConnect.cpp
index e9e50bb7f90..b6f671a53de 100644
--- a/js/xpconnect/src/nsXPConnect.cpp
+++ b/js/xpconnect/src/nsXPConnect.cpp
@@ -88,7 +88,7 @@ nsXPConnect::nsXPConnect()
 
 nsXPConnect::~nsXPConnect()
 {
-    mRuntime->DeleteJunkScope();
+    mRuntime->DeleteSingletonScopes();
     mRuntime->DestroyJSContextStack();
 
     // In order to clean up everything properly, we need to GC twice: once now,
diff --git a/js/xpconnect/src/xpcprivate.h b/js/xpconnect/src/xpcprivate.h
index 54d1c8cc081..ef0696381e0 100644
--- a/js/xpconnect/src/xpcprivate.h
+++ b/js/xpconnect/src/xpcprivate.h
@@ -557,7 +557,8 @@ public:
     AutoMarkingPtr**  GetAutoRootsAdr() {return &mAutoRoots;}
 
     JSObject* GetJunkScope();
-    void DeleteJunkScope();
+    JSObject* GetCompilationScope();
+    void DeleteSingletonScopes();
 
     PRTime GetWatchdogTimestamp(WatchdogTimestampCategory aCategory);
     void OnAfterProcessNextEvent() { mSlowScriptCheckpoint = mozilla::TimeStamp(); }
@@ -598,6 +599,7 @@ private:
     nsRefPtr<WatchdogManager> mWatchdogManager;
     JS::GCSliceCallback mPrevGCSliceCallback;
     JS::PersistentRootedObject mJunkScope;
+    JS::PersistentRootedObject mCompilationScope;
     nsRefPtr<AsyncFreeSnowWhite> mAsyncSnowWhiteFreer;
 
     mozilla::TimeStamp mSlowScriptCheckpoint;
diff --git a/js/xpconnect/src/xpcpublic.h b/js/xpconnect/src/xpcpublic.h
index 14f51b4b44d..4a01a97ba78 100644
--- a/js/xpconnect/src/xpcpublic.h
+++ b/js/xpconnect/src/xpcpublic.h
@@ -435,6 +435,14 @@ GetJunkScope();
 nsIGlobalObject *
 GetJunkScopeGlobal();
 
+/**
+ * Shared compilation scope for XUL prototype documents and XBL
+ * precompilation. This compartment has a null principal. No code may run, and
+ * it is invisible to the debugger.
+ */
+JSObject *
+GetCompilationScope();
+
 /**
  * If |aObj| is a window, returns the associated nsGlobalWindow.
  * Otherwise, returns null.