dom/base/MozQueryInterface.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 #include "ChromeUtils.h"
   8 #include "MozQueryInterface.h"
   9 #include "xptinfo.h"
  10
  11 #include <string.h>
  12
  13 #include "jsapi.h"
  14
  15 #include "mozilla/ErrorResult.h"
  16 #include "xpcpublic.h"
  17
  18 namespace mozilla::dom {
  19
  20 constexpr size_t IID_SIZE = sizeof(nsIID);
  21
  22 static_assert(
  23     IID_SIZE == 16,
  24     "Size of nsID struct changed. Please ensure this code is still valid.");
  25
  26 static int CompareIIDs(const nsIID& aA, const nsIID& aB) {
  27   return memcmp((void*)&aA.m0, (void*)&aB.m0, IID_SIZE);
  28 }
  29
  30 /* static */
  31 MozQueryInterface* ChromeUtils::GenerateQI(
  32     const GlobalObject& aGlobal, const Sequence<JS::Value>& aInterfaces,
  33     ErrorResult& aRv) {
  34   JSContext* cx = aGlobal.Context();
  35
  36   nsTArray<nsIID> ifaces;
  37
  38   JS::RootedValue iface(cx);
  39   for (uint32_t idx = 0; idx < aInterfaces.Length(); ++idx) {
  40     iface = aInterfaces[idx];
  41
  42     // Handle ID objects
  43     if (Maybe<nsID> id = xpc::JSValue2ID(cx, iface)) {
  44       ifaces.AppendElement(*id);
  45       continue;
  46     }
  47
  48     // Accept string valued names
  49     if (iface.isString()) {
  50       JS::UniqueChars name = JS_EncodeStringToLatin1(cx, iface.toString());
  51
  52       const nsXPTInterfaceInfo* iinfo = nsXPTInterfaceInfo::ByName(name.get());
  53       if (iinfo) {
  54         ifaces.AppendElement(iinfo->IID());
  55         continue;
  56       }
  57     }
  58
  59     // NOTE: We ignore unknown interfaces here because in some cases we try to
  60     // pass them in to support multiple platforms.
  61   }
  62
  63   MOZ_ASSERT(!ifaces.Contains(NS_GET_IID(nsISupports), CompareIIDs));
  64   ifaces.AppendElement(NS_GET_IID(nsISupports));
  65
  66   ifaces.Sort(CompareIIDs);
  67
  68   return new MozQueryInterface(std::move(ifaces));
  69 }
  70
  71 bool MozQueryInterface::QueriesTo(const nsIID& aIID) const {
  72   return mInterfaces.ContainsSorted(aIID, CompareIIDs);
  73 }
  74
  75 void MozQueryInterface::LegacyCall(JSContext* cx, JS::Handle<JS::Value> thisv,
  76                                    JS::Handle<JS::Value> aIID,
  77                                    JS::MutableHandle<JS::Value> aResult,
  78                                    ErrorResult& aRv) const {
  79   Maybe<nsID> id = xpc::JSValue2ID(cx, aIID);
  80   if (id && QueriesTo(*id)) {
  81     aResult.set(thisv);
  82   } else {
  83     aRv.Throw(NS_ERROR_NO_INTERFACE);
  84   }
  85 }
  86
  87 bool MozQueryInterface::WrapObject(JSContext* aCx,
  88                                    JS::Handle<JSObject*> aGivenProto,
  89                                    JS::MutableHandle<JSObject*> aReflector) {
  90   return MozQueryInterface_Binding::Wrap(aCx, this, aGivenProto, aReflector);
  91 }
  92
  93 }  // namespace mozilla::dom