Bug 1667455 - Part 1: Define Services in all system globals. r=kmag

`Services` object is created in the loader's shared global, and it is defined
on all globals without OMIT_COMPONENTS_OBJECT.

Differential Revision: https://phabricator.services.mozilla.com/D150890

js/xpconnect/loader/mozJSModuleLoader.cpp

@@ -48,6 +48,7 @@
 #include "WrapperFactory.h"
 #include "JSMEnvironmentProxy.h"
 #include "ModuleEnvironmentProxy.h"
+#include "JSServices.h"
 
 #include "mozilla/scache/StartupCache.h"
 #include "mozilla/scache/StartupCacheUtils.h"
@@ -266,7 +267,8 @@ mozJSModuleLoader::mozJSModuleLoader()
       mFallbackImports(16),
       mLocations(16),
       mInitialized(false),
-      mLoaderGlobal(dom::RootingCx()) {
+      mLoaderGlobal(dom::RootingCx()),
+      mServicesObj(dom::RootingCx()) {
   MOZ_ASSERT(!sSelf, "mozJSModuleLoader should be a singleton");
 }
 
@@ -545,10 +547,18 @@ void mozJSModuleLoader::CreateLoaderGlobal(JSContext* aCx,
   // been defined so the JS debugger can tell what module the global is
   // for
   RootedObject global(aCx);
+
+#ifdef DEBUG
+  // See mozJSModuleLoader::DefineJSServices.
+  mIsInitializingLoaderGlobal = true;
+#endif
   nsresult rv = xpc::InitClassesWithNewWrappedGlobal(
       aCx, static_cast<nsIGlobalObject*>(backstagePass),
       nsContentUtils::GetSystemPrincipal(), xpc::DONT_FIRE_ONNEWGLOBALHOOK,
       options, &global);
+#ifdef DEBUG
+  mIsInitializingLoaderGlobal = false;
+#endif
   NS_ENSURE_SUCCESS_VOID(rv);
 
   NS_ENSURE_TRUE_VOID(global);
@@ -560,6 +570,14 @@ void mozJSModuleLoader::CreateLoaderGlobal(JSContext* aCx,
     return;
   }
 
+  if (!CreateJSServices(aCx)) {
+    return;
+  }
+
+  if (!DefineJSServices(aCx, global)) {
+    return;
+  }
+
   // Set the location information for the new global, so that tools like
   // about:memory may use that information
   xpc::SetLocationForGlobal(global, aLocation);
@@ -959,6 +977,7 @@ void mozJSModuleLoader::UnloadModules() {
     JS_SetAllNonReservedSlotsToUndefined(mLoaderGlobal);
     mLoaderGlobal = nullptr;
   }
+  mServicesObj = nullptr;
 
   mFallbackImports.Clear();
   mInProgressImports.Clear();
@@ -1637,6 +1656,41 @@ nsresult mozJSModuleLoader::Unload(const nsACString& aLocation) {
   return NS_OK;
 }
 
+bool mozJSModuleLoader::CreateJSServices(JSContext* aCx) {
+  JSObject* services = NewJSServices(aCx);
+  if (!services) {
+    return false;
+  }
+
+  mServicesObj = services;
+  return true;
+}
+
+bool mozJSModuleLoader::DefineJSServices(JSContext* aCx,
+                                         JS::Handle<JSObject*> aGlobal) {
+  if (!mServicesObj) {
+    // This function is called whenever creating a new global that needs
+    // `Services`, including the loader's shared global.
+    //
+    // This function is no-op if it's called during creating the loader's
+    // shared global.
+    //
+    // See also  CreateAndDefineJSServices.
+    MOZ_ASSERT(!mLoaderGlobal);
+    MOZ_ASSERT(mIsInitializingLoaderGlobal);
+    return true;
+  }
+
+  JS::Rooted<JS::Value> services(aCx, ObjectValue(*mServicesObj));
+  if (!JS_WrapValue(aCx, &services)) {
+    return false;
+  }
+
+  JS::Rooted<JS::PropertyKey> servicesId(
+      aCx, XPCJSContext::Get()->GetStringID(XPCJSContext::IDX_SERVICES));
+  return JS_DefinePropertyById(aCx, aGlobal, servicesId, services, 0);
+}
+
 size_t mozJSModuleLoader::ModuleEntry::SizeOfIncludingThis(
     MallocSizeOf aMallocSizeOf) const {
   size_t n = aMallocSizeOf(this);

js/xpconnect/loader/mozJSModuleLoader.h

@@ -104,6 +104,8 @@ class mozJSModuleLoader final : public nsIMemoryReporter {
 
   size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf);
 
+  bool DefineJSServices(JSContext* aCx, JS::Handle<JSObject*> aGlobal);
+
  protected:
   mozJSModuleLoader();
   ~mozJSModuleLoader();
@@ -118,6 +120,8 @@ class mozJSModuleLoader final : public nsIMemoryReporter {
   void CreateLoaderGlobal(JSContext* aCx, const nsACString& aLocation,
                           JS::MutableHandleObject aGlobal);
 
+  bool CreateJSServices(JSContext* aCx);
+
   JSObject* GetSharedGlobal(JSContext* aCx);
 
   static nsresult GetSourceFile(nsIURI* aResolvedURI, nsIFile** aSourceFileOut);
@@ -227,7 +231,11 @@ class mozJSModuleLoader final : public nsIMemoryReporter {
   nsClassHashtable<nsCStringHashKey, nsCString> mLocations;
 
   bool mInitialized;
+#ifdef DEBUG
+  bool mIsInitializingLoaderGlobal = false;
+#endif
   JS::PersistentRooted<JSObject*> mLoaderGlobal;
+  JS::PersistentRooted<JSObject*> mServicesObj;
 
   RefPtr<mozilla::loader::ComponentModuleLoader> mModuleLoader;
 };

js/xpconnect/src/XPCJSRuntime.cpp

@@ -103,6 +103,7 @@ const char* const XPCJSRuntime::mStrings[] = {
     "Ci",               // IDX_CI
     "Cr",               // IDX_CR
     "Cu",               // IDX_CU
+    "Services",         // IDX_SERVICES
     "wrappedJSObject",  // IDX_WRAPPED_JSOBJECT
     "prototype",        // IDX_PROTOTYPE
     "eval",             // IDX_EVAL

js/xpconnect/src/moz.build

@@ -6,6 +6,7 @@
 
 EXPORTS += [
     "BackstagePass.h",
+    "JSServices.h",
     "XPCJSMemoryReporter.h",
     "xpcObjectHelper.h",
     "xpcpublic.h",

js/xpconnect/src/nsXPConnect.cpp

@@ -26,6 +26,7 @@
 
 #include "WrapperFactory.h"
 #include "AccessCheck.h"
+#include "JSServices.h"
 
 #include "mozilla/BasePrincipal.h"
 #include "mozilla/dom/BindingUtils.h"
@@ -512,6 +513,10 @@ bool InitGlobalObject(JSContext* aJSContext, JS::Handle<JSObject*> aGlobal,
         !XPCNativeWrapper::AttachNewConstructorObject(aJSContext, aGlobal)) {
       return UnexpectedFailure(false);
     }
+
+    if (!mozJSModuleLoader::Get()->DefineJSServices(aJSContext, aGlobal)) {
+      return UnexpectedFailure(false);
+    }
   }
 
   if (!(aFlags & xpc::DONT_FIRE_ONNEWGLOBALHOOK)) {

js/xpconnect/src/xpcprivate.h

@@ -379,6 +379,7 @@ class XPCJSContext final : public mozilla::CycleCollectedJSContext,
     IDX_CI,
     IDX_CR,
     IDX_CU,
+    IDX_SERVICES,
     IDX_WRAPPED_JSOBJECT,
     IDX_PROTOTYPE,
     IDX_EVAL,