js/xpconnect/src/XPCCallContext.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 /* Call context. */
   8
   9 #include "xpcprivate.h"
  10 #include "jsfriendapi.h"
  11 #include "js/Object.h"  // JS::GetClass, JS::GetReservedSlot
  12 #include "js/Wrapper.h"
  13 #include "nsContentUtils.h"
  14
  15 using namespace mozilla;
  16 using namespace xpc;
  17 using namespace JS;
  18
  19 static inline bool IsTearoffClass(const JSClass* clazz) {
  20   return clazz == &XPC_WN_Tearoff_JSClass;
  21 }
  22
  23 XPCCallContext::XPCCallContext(
  24     JSContext* cx, HandleObject obj /* = nullptr               */,
  25     HandleObject funobj /* = nullptr               */,
  26     HandleId name /* = JSID_VOID             */, unsigned argc /* = NO_ARGS */,
  27     Value* argv /* = nullptr */, Value* rval /* = nullptr               */)
  28     : mState(INIT_FAILED),
  29       mXPC(nsXPConnect::XPConnect()),
  30       mXPCJSContext(nullptr),
  31       mJSContext(cx),
  32       mWrapper(nullptr),
  33       mTearOff(nullptr),
  34       mMember(nullptr),
  35       mName(cx),
  36       mStaticMemberIsLocal(false),
  37       mArgc(0),
  38       mArgv(nullptr),
  39       mRetVal(nullptr) {
  40   MOZ_ASSERT(cx);
  41   MOZ_ASSERT(cx == nsContentUtils::GetCurrentJSContext());
  42
  43   if (!mXPC) {
  44     return;
  45   }
  46
  47   mXPCJSContext = XPCJSContext::Get();
  48
  49   // hook into call context chain.
  50   mPrevCallContext = mXPCJSContext->SetCallContext(this);
  51
  52   mState = HAVE_CONTEXT;
  53
  54   if (!obj) {
  55     return;
  56   }
  57
  58   mMethodIndex = 0xDEAD;
  59
  60   mState = HAVE_OBJECT;
  61
  62   mTearOff = nullptr;
  63
  64   JSObject* unwrapped =
  65       js::CheckedUnwrapDynamic(obj, cx, /* stopAtWindowProxy = */ false);
  66   if (!unwrapped) {
  67     JS_ReportErrorASCII(mJSContext,
  68                         "Permission denied to call method on |this|");
  69     mState = INIT_FAILED;
  70     return;
  71   }
  72   const JSClass* clasp = JS::GetClass(unwrapped);
  73   if (clasp->isWrappedNative()) {
  74     mWrapper = XPCWrappedNative::Get(unwrapped);
  75   } else if (IsTearoffClass(clasp)) {
  76     mTearOff = XPCWrappedNativeTearOff::Get(unwrapped);
  77     mWrapper = XPCWrappedNative::Get(
  78         &JS::GetReservedSlot(unwrapped, XPCWrappedNativeTearOff::FlatObjectSlot)
  79              .toObject());
  80   }
  81   if (mWrapper && !mTearOff) {
  82     mScriptable = mWrapper->GetScriptable();
  83   }
  84
  85   if (!name.isVoid()) {
  86     SetName(name);
  87   }
  88
  89   if (argc != NO_ARGS) {
  90     SetArgsAndResultPtr(argc, argv, rval);
  91   }
  92
  93   CHECK_STATE(HAVE_OBJECT);
  94 }
  95
  96 void XPCCallContext::SetName(jsid name) {
  97   CHECK_STATE(HAVE_OBJECT);
  98
  99   mName = name;
 100
 101   if (mTearOff) {
 102     mSet = nullptr;
 103     mInterface = mTearOff->GetInterface();
 104     mMember = mInterface->FindMember(mName);
 105     mStaticMemberIsLocal = true;
 106     if (mMember && !mMember->IsConstant()) {
 107       mMethodIndex = mMember->GetIndex();
 108     }
 109   } else {
 110     mSet = mWrapper ? mWrapper->GetSet() : nullptr;
 111
 112     if (mSet &&
 113         mSet->FindMember(
 114             mName, &mMember, &mInterface,
 115             mWrapper->HasProto() ? mWrapper->GetProto()->GetSet() : nullptr,
 116             &mStaticMemberIsLocal)) {
 117       if (mMember && !mMember->IsConstant()) {
 118         mMethodIndex = mMember->GetIndex();
 119       }
 120     } else {
 121       mMember = nullptr;
 122       mInterface = nullptr;
 123       mStaticMemberIsLocal = false;
 124     }
 125   }
 126
 127   mState = HAVE_NAME;
 128 }
 129
 130 void XPCCallContext::SetCallInfo(XPCNativeInterface* iface,
 131                                  XPCNativeMember* member, bool isSetter) {
 132   CHECK_STATE(HAVE_CONTEXT);
 133
 134   // We are going straight to the method info and need not do a lookup
 135   // by id.
 136
 137   // don't be tricked if method is called with wrong 'this'
 138   if (mTearOff && mTearOff->GetInterface() != iface) {
 139     mTearOff = nullptr;
 140   }
 141
 142   mSet = nullptr;
 143   mInterface = iface;
 144   mMember = member;
 145   mMethodIndex = mMember->GetIndex() + (isSetter ? 1 : 0);
 146   mName = mMember->GetName();
 147
 148   if (mState < HAVE_NAME) {
 149     mState = HAVE_NAME;
 150   }
 151 }
 152
 153 void XPCCallContext::SetArgsAndResultPtr(unsigned argc, Value* argv,
 154                                          Value* rval) {
 155   CHECK_STATE(HAVE_OBJECT);
 156
 157   if (mState < HAVE_NAME) {
 158     mSet = nullptr;
 159     mInterface = nullptr;
 160     mMember = nullptr;
 161     mStaticMemberIsLocal = false;
 162   }
 163
 164   mArgc = argc;
 165   mArgv = argv;
 166   mRetVal = rval;
 167
 168   mState = HAVE_ARGS;
 169 }
 170
 171 nsresult XPCCallContext::CanCallNow() {
 172   nsresult rv;
 173
 174   if (!HasInterfaceAndMember()) {
 175     return NS_ERROR_UNEXPECTED;
 176   }
 177   if (mState < HAVE_ARGS) {
 178     return NS_ERROR_UNEXPECTED;
 179   }
 180
 181   if (!mTearOff) {
 182     mTearOff = mWrapper->FindTearOff(mJSContext, mInterface, false, &rv);
 183     if (!mTearOff || mTearOff->GetInterface() != mInterface) {
 184       mTearOff = nullptr;
 185       return NS_FAILED(rv) ? rv : NS_ERROR_UNEXPECTED;
 186     }
 187   }
 188
 189   // Refresh in case FindTearOff extended the set
 190   mSet = mWrapper->GetSet();
 191
 192   mState = READY_TO_CALL;
 193   return NS_OK;
 194 }
 195
 196 void XPCCallContext::SystemIsBeingShutDown() {
 197   // XXX This is pretty questionable since the per thread cleanup stuff
 198   // can be making this call on one thread for call contexts on another
 199   // thread.
 200   NS_WARNING(
 201       "Shutting Down XPConnect even through there is a live XPCCallContext");
 202   mXPCJSContext = nullptr;
 203   mState = SYSTEM_SHUTDOWN;
 204   mSet = nullptr;
 205   mInterface = nullptr;
 206
 207   if (mPrevCallContext) {
 208     mPrevCallContext->SystemIsBeingShutDown();
 209   }
 210 }
 211
 212 XPCCallContext::~XPCCallContext() {
 213   if (mXPCJSContext) {
 214     DebugOnly<XPCCallContext*> old =
 215         mXPCJSContext->SetCallContext(mPrevCallContext);
 216     MOZ_ASSERT(old == this, "bad pop from per thread data");
 217   }
 218 }