dom/bindings/nsScriptErrorWithStack.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 /*
   8  * nsScriptErrorWithStack implementation.
   9  * a main-thread-only, cycle-collected subclass of nsScriptErrorBase
  10  * that can store a SavedFrame stack trace object.
  11  */
  12
  13 #include "nsScriptError.h"
  14 #include "MainThreadUtils.h"
  15 #include "mozilla/Assertions.h"
  16 #include "mozilla/HoldDropJSObjects.h"
  17 #include "mozilla/dom/ScriptSettings.h"
  18 #include "js/Wrapper.h"
  19 #include "nsCycleCollectionParticipant.h"
  20 #include "nsGlobalWindowInner.h"
  21 #include "nsJSUtils.h"
  22
  23 using namespace mozilla::dom;
  24
  25 namespace {
  26
  27 static nsCString FormatStackString(JSContext* cx, JSPrincipals* aPrincipals,
  28                                    JS::Handle<JSObject*> aStack) {
  29   JS::Rooted<JSString*> formattedStack(cx);
  30   if (!JS::BuildStackString(cx, aPrincipals, aStack, &formattedStack)) {
  31     return nsCString();
  32   }
  33
  34   nsAutoJSString stackJSString;
  35   if (!stackJSString.init(cx, formattedStack)) {
  36     return nsCString();
  37   }
  38
  39   return NS_ConvertUTF16toUTF8(stackJSString.get());
  40 }
  41
  42 }  // namespace
  43
  44 NS_IMPL_CYCLE_COLLECTION_CLASS(nsScriptErrorWithStack)
  45
  46 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsScriptErrorWithStack)
  47   tmp->mException.setUndefined();
  48   tmp->mStack = nullptr;
  49   tmp->mStackGlobal = nullptr;
  50 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
  51
  52 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsScriptErrorWithStack)
  53 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
  54
  55 NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(nsScriptErrorWithStack)
  56   NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mException)
  57   NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mStack)
  58   NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mStackGlobal)
  59 NS_IMPL_CYCLE_COLLECTION_TRACE_END
  60
  61 NS_IMPL_CYCLE_COLLECTING_ADDREF(nsScriptErrorWithStack)
  62 NS_IMPL_CYCLE_COLLECTING_RELEASE(nsScriptErrorWithStack)
  63
  64 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsScriptErrorWithStack)
  65   NS_INTERFACE_MAP_ENTRY(nsISupports)
  66   NS_INTERFACE_MAP_ENTRY(nsIConsoleMessage)
  67   NS_INTERFACE_MAP_ENTRY(nsIScriptError)
  68 NS_INTERFACE_MAP_END
  69
  70 nsScriptErrorWithStack::nsScriptErrorWithStack(
  71     JS::Handle<mozilla::Maybe<JS::Value>> aException,
  72     JS::Handle<JSObject*> aStack, JS::Handle<JSObject*> aStackGlobal)
  73     : mStack(aStack), mStackGlobal(aStackGlobal) {
  74   MOZ_ASSERT(NS_IsMainThread(), "You can't use this class on workers.");
  75
  76   if (aException.isSome()) {
  77     mHasException = true;
  78     mException.set(*aException);
  79   } else {
  80     mHasException = false;
  81     mException.setUndefined();
  82   }
  83
  84   if (mStack) {
  85     MOZ_ASSERT(JS_IsGlobalObject(mStackGlobal));
  86     js::AssertSameCompartment(mStack, mStackGlobal);
  87   } else {
  88     MOZ_ASSERT(!mStackGlobal);
  89   }
  90
  91   mozilla::HoldJSObjects(this);
  92 }
  93
  94 nsScriptErrorWithStack::~nsScriptErrorWithStack() {
  95   mozilla::DropJSObjects(this);
  96 }
  97
  98 NS_IMETHODIMP
  99 nsScriptErrorWithStack::GetHasException(bool* aHasException) {
 100   *aHasException = mHasException;
 101   return NS_OK;
 102 }
 103
 104 NS_IMETHODIMP
 105 nsScriptErrorWithStack::GetException(JS::MutableHandle<JS::Value> aException) {
 106   aException.set(mException);
 107   return NS_OK;
 108 }
 109
 110 NS_IMETHODIMP
 111 nsScriptErrorWithStack::GetStack(JS::MutableHandle<JS::Value> aStack) {
 112   aStack.setObjectOrNull(mStack);
 113   return NS_OK;
 114 }
 115
 116 NS_IMETHODIMP
 117 nsScriptErrorWithStack::GetStackGlobal(
 118     JS::MutableHandle<JS::Value> aStackGlobal) {
 119   aStackGlobal.setObjectOrNull(mStackGlobal);
 120   return NS_OK;
 121 }
 122
 123 NS_IMETHODIMP
 124 nsScriptErrorWithStack::ToString(nsACString& /*UTF8*/ aResult) {
 125   MOZ_ASSERT(NS_IsMainThread());
 126
 127   nsCString message;
 128   nsresult rv = nsScriptErrorBase::ToString(message);
 129   NS_ENSURE_SUCCESS(rv, rv);
 130
 131   if (!mStack) {
 132     aResult.Assign(message);
 133     return NS_OK;
 134   }
 135
 136   AutoJSAPI jsapi;
 137   if (!jsapi.Init(mStackGlobal)) {
 138     return NS_ERROR_FAILURE;
 139   }
 140
 141   JSPrincipals* principals =
 142       JS::GetRealmPrincipals(js::GetNonCCWObjectRealm(mStackGlobal));
 143
 144   JSContext* cx = jsapi.cx();
 145   JS::Rooted<JSObject*> stack(cx, mStack);
 146   nsCString stackString = FormatStackString(cx, principals, stack);
 147   nsCString combined = message + "\n"_ns + stackString;
 148   aResult.Assign(combined);
 149
 150   return NS_OK;
 151 }
 152
 153 static bool IsObjectGlobalDying(JSObject* aObj) {
 154   // CCWs are not associated with a single global
 155   if (js::IsCrossCompartmentWrapper(aObj)) {
 156     return false;
 157   }
 158
 159   nsGlobalWindowInner* win = xpc::WindowGlobalOrNull(aObj);
 160   return win && win->IsDying();
 161 }
 162
 163 already_AddRefed<nsScriptErrorBase> CreateScriptError(
 164     nsGlobalWindowInner* win, JS::Handle<mozilla::Maybe<JS::Value>> aException,
 165     JS::Handle<JSObject*> aStack, JS::Handle<JSObject*> aStackGlobal) {
 166   bool createWithStack = true;
 167   if (aException.isNothing() && !aStack) {
 168     // Neither stack nor exception, do not need nsScriptErrorWithStack.
 169     createWithStack = false;
 170   } else if (win && (win->IsDying() || !win->WindowID())) {
 171     // The window is already dying or we don't have a WindowID,
 172     // this means nsConsoleService::ClearMessagesForWindowID
 173     // would be unable to cleanup this error.
 174     createWithStack = false;
 175   } else if ((aStackGlobal && IsObjectGlobalDying(aStackGlobal)) ||
 176              (aException.isSome() && aException.value().isObject() &&
 177               IsObjectGlobalDying(&aException.value().toObject()))) {
 178     // Prevent leaks by not creating references to already dying globals.
 179     createWithStack = false;
 180   }
 181
 182   if (!createWithStack) {
 183     RefPtr<nsScriptErrorBase> error = new nsScriptError();
 184     return error.forget();
 185   }
 186
 187   RefPtr<nsScriptErrorBase> error =
 188       new nsScriptErrorWithStack(aException, aStack, aStackGlobal);
 189   return error.forget();
 190 }