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   JSContext* cx = aGlobal.Context();
  34
  35   nsTArray<nsIID> ifaces;
  36
  37   JS::Rooted<JS::Value> iface(cx);
  38   for (uint32_t idx = 0; idx < aInterfaces.Length(); ++idx) {
  39     iface = aInterfaces[idx];
  40
  41     // Handle ID objects
  42     if (Maybe<nsID> id = xpc::JSValue2ID(cx, iface)) {
  43       ifaces.AppendElement(*id);
  44       continue;
  45     }
  46
  47     // Accept string valued names
  48     if (iface.isString()) {
  49       JS::UniqueChars name = JS_EncodeStringToLatin1(cx, iface.toString());
  50
  51       const nsXPTInterfaceInfo* iinfo = nsXPTInterfaceInfo::ByName(name.get());
  52       if (iinfo) {
  53         ifaces.AppendElement(iinfo->IID());
  54         continue;
  55       }
  56     }
  57
  58     // NOTE: We ignore unknown interfaces here because in some cases we try to
  59     // pass them in to support multiple platforms.
  60   }
  61
  62   MOZ_ASSERT(!ifaces.Contains(NS_GET_IID(nsISupports), CompareIIDs));
  63   ifaces.AppendElement(NS_GET_IID(nsISupports));
  64
  65   ifaces.Sort(CompareIIDs);
  66
  67   return new MozQueryInterface(std::move(ifaces));
  68 }
  69
  70 bool MozQueryInterface::QueriesTo(const nsIID& aIID) const {
  71   return mInterfaces.ContainsSorted(aIID, CompareIIDs);
  72 }
  73
  74 void MozQueryInterface::LegacyCall(JSContext* cx, JS::Handle<JS::Value> thisv,
  75                                    JS::Handle<JS::Value> aIID,
  76                                    JS::MutableHandle<JS::Value> aResult,
  77                                    ErrorResult& aRv) const {
  78   Maybe<nsID> id = xpc::JSValue2ID(cx, aIID);
  79   if (id && QueriesTo(*id)) {
  80     aResult.set(thisv);
  81   } else {
  82     aRv.Throw(NS_ERROR_NO_INTERFACE);
  83   }
  84 }
  85
  86 bool MozQueryInterface::WrapObject(JSContext* aCx,
  87                                    JS::Handle<JSObject*> aGivenProto,
  88                                    JS::MutableHandle<JSObject*> aReflector) {
  89   return MozQueryInterface_Binding::Wrap(aCx, this, aGivenProto, aReflector);
  90 }
  91
  92 }  // namespace mozilla::dom