js/xpconnect/src/XPCWrappedNativeProto.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Shared proto object for XPCWrappedNative. */
   8
   9 #include "xpcprivate.h"
  10 #include "js/Object.h"  // JS::SetReservedSlot
  11 #include "pratom.h"
  12 #include "XPCMaps.h"
  13
  14 using namespace mozilla;
  15
  16 #ifdef DEBUG
  17 int32_t XPCWrappedNativeProto::gDEBUG_LiveProtoCount = 0;
  18 #endif
  19
  20 XPCWrappedNativeProto::XPCWrappedNativeProto(XPCWrappedNativeScope* Scope,
  21                                              nsIClassInfo* ClassInfo,
  22                                              RefPtr<XPCNativeSet>&& Set)
  23     : mScope(Scope),
  24       mJSProtoObject(nullptr),
  25       mClassInfo(ClassInfo),
  26       mSet(std::move(Set)) {
  27   // This native object lives as long as its associated JSObject - killed
  28   // by finalization of the JSObject (or explicitly if Init fails).
  29
  30   MOZ_COUNT_CTOR(XPCWrappedNativeProto);
  31   MOZ_ASSERT(mScope);
  32
  33 #ifdef DEBUG
  34   gDEBUG_LiveProtoCount++;
  35 #endif
  36 }
  37
  38 XPCWrappedNativeProto::~XPCWrappedNativeProto() {
  39   MOZ_ASSERT(!mJSProtoObject, "JSProtoObject still alive");
  40
  41   MOZ_COUNT_DTOR(XPCWrappedNativeProto);
  42
  43 #ifdef DEBUG
  44   gDEBUG_LiveProtoCount--;
  45 #endif
  46
  47   // Note that our weak ref to mScope is not to be trusted at this point.
  48
  49   XPCNativeSet::ClearCacheEntryForClassInfo(mClassInfo);
  50
  51   DeferredFinalize(mClassInfo.forget().take());
  52 }
  53
  54 bool XPCWrappedNativeProto::Init(JSContext* cx, nsIXPCScriptable* scriptable) {
  55   mScriptable = scriptable;
  56
  57   JS::RootedObject proto(cx, JS::GetRealmObjectPrototype(cx));
  58   mJSProtoObject = JS_NewObjectWithGivenProto(cx, &XPC_WN_Proto_JSClass, proto);
  59
  60   bool success = !!mJSProtoObject;
  61   if (success) {
  62     JS::SetReservedSlot(mJSProtoObject, ProtoSlot, JS::PrivateValue(this));
  63   }
  64
  65   return success;
  66 }
  67
  68 void XPCWrappedNativeProto::JSProtoObjectFinalized(JS::GCContext* gcx,
  69                                                    JSObject* obj) {
  70   MOZ_ASSERT(obj == mJSProtoObject, "huh?");
  71
  72 #ifdef DEBUG
  73   // Check that this object has already been swept from the map.
  74   ClassInfo2WrappedNativeProtoMap* map = GetScope()->GetWrappedNativeProtoMap();
  75   MOZ_ASSERT(map->Find(mClassInfo) != this);
  76 #endif
  77
  78   MOZ_ALWAYS_TRUE(GetRuntime()->GetDyingWrappedNativeProtos().append(this));
  79   mJSProtoObject = nullptr;
  80 }
  81
  82 void XPCWrappedNativeProto::JSProtoObjectMoved(JSObject* obj,
  83                                                const JSObject* old) {
  84   // Update without triggering barriers.
  85   MOZ_ASSERT(mJSProtoObject == old);
  86   mJSProtoObject.unbarrieredSet(obj);
  87 }
  88
  89 void XPCWrappedNativeProto::SystemIsBeingShutDown() {
  90   // Note that the instance might receive this call multiple times
  91   // as we walk to here from various places.
  92
  93   if (mJSProtoObject) {
  94     // short circuit future finalization
  95     JS::SetReservedSlot(mJSProtoObject, ProtoSlot, JS::UndefinedValue());
  96     mJSProtoObject = nullptr;
  97   }
  98 }
  99
 100 // static
 101 XPCWrappedNativeProto* XPCWrappedNativeProto::GetNewOrUsed(
 102     JSContext* cx, XPCWrappedNativeScope* scope, nsIClassInfo* classInfo,
 103     nsIXPCScriptable* scriptable) {
 104   MOZ_ASSERT(scope, "bad param");
 105   MOZ_ASSERT(classInfo, "bad param");
 106
 107   AutoMarkingWrappedNativeProtoPtr proto(cx);
 108   ClassInfo2WrappedNativeProtoMap* map = nullptr;
 109
 110   map = scope->GetWrappedNativeProtoMap();
 111   proto = map->Find(classInfo);
 112   if (proto) {
 113     return proto;
 114   }
 115
 116   RefPtr<XPCNativeSet> set = XPCNativeSet::GetNewOrUsed(cx, classInfo);
 117   if (!set) {
 118     return nullptr;
 119   }
 120
 121   proto = new XPCWrappedNativeProto(scope, classInfo, std::move(set));
 122
 123   if (!proto->Init(cx, scriptable)) {
 124     delete proto.get();
 125     return nullptr;
 126   }
 127
 128   map->Add(classInfo, proto);
 129
 130   return proto;
 131 }
 132
 133 void XPCWrappedNativeProto::DebugDump(int16_t depth) {
 134 #ifdef DEBUG
 135   depth--;
 136   XPC_LOG_ALWAYS(("XPCWrappedNativeProto @ %p", this));
 137   XPC_LOG_INDENT();
 138   XPC_LOG_ALWAYS(("gDEBUG_LiveProtoCount is %d", gDEBUG_LiveProtoCount));
 139   XPC_LOG_ALWAYS(("mScope @ %p", mScope));
 140   XPC_LOG_ALWAYS(("mJSProtoObject @ %p", mJSProtoObject.get()));
 141   XPC_LOG_ALWAYS(("mSet @ %p", mSet.get()));
 142   XPC_LOG_ALWAYS(("mScriptable @ %p", mScriptable.get()));
 143   if (depth && mScriptable) {
 144     XPC_LOG_INDENT();
 145     XPC_LOG_ALWAYS(("mFlags of %x", mScriptable->GetScriptableFlags()));
 146     XPC_LOG_ALWAYS(("mJSClass @ %p", mScriptable->GetJSClass()));
 147     XPC_LOG_OUTDENT();
 148   }
 149   XPC_LOG_OUTDENT();
 150 #endif
 151 }