The Tor Browser: dom/bindings/Exceptions.cpp@97036ab72558 (annotated)

dom/bindings/Exceptions.cpp@97036ab72558 (annotated)

dom/bindings/Exceptions.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "mozilla/dom/Exceptions.h"
 #include "js/GCAPI.h"
 #include "js/OldDebugAPI.h"
 #include "jsapi.h"
 #include "jsprf.h"
 #include "mozilla/CycleCollectedJSRuntime.h"
 #include "mozilla/dom/BindingUtils.h"
 #include "mozilla/dom/DOMException.h"
 #include "nsServiceManagerUtils.h"
 #include "nsThreadUtils.h"
 #include "XPCWrapper.h"
 #include "WorkerPrivate.h"
 #include "nsContentUtils.h"
 namespace {
 // We can't use nsContentUtils::IsCallerChrome because it might not exist in
 // xpcshell.
 bool
 IsCallerChrome()
 {
   nsCOMPtr<nsIScriptSecurityManager> secMan;
   secMan = XPCWrapper::GetSecurityManager();
   if (!secMan) {
     return false;
   }
   bool isChrome;
   return NS_SUCCEEDED(secMan->SubjectPrincipalIsSystem(&isChrome)) && isChrome;
 }
 } // anonymous namespace
 namespace mozilla {
 namespace dom {
 bool
 ThrowExceptionObject(JSContext* aCx, nsIException* aException)
 {
   // See if we really have an Exception.
   nsCOMPtr<Exception> exception = do_QueryInterface(aException);
   if (exception) {
     return ThrowExceptionObject(aCx, exception);
   }
   // We only have an nsIException (probably an XPCWrappedJS).  Fall back on old
   // wrapping.
   MOZ_ASSERT(NS_IsMainThread());
   JS::Rooted<JSObject*> glob(aCx, JS::CurrentGlobalOrNull(aCx));
   if (!glob) {
     // XXXbz Can this really be null here?
     return false;
   }
   JS::Rooted<JS::Value> val(aCx);
   if (!WrapObject(aCx, aException, &NS_GET_IID(nsIException), &val)) {
     return false;
   }
   JS_SetPendingException(aCx, val);
   return true;
 }
 bool
 ThrowExceptionObject(JSContext* aCx, Exception* aException)
 {
   JS::Rooted<JS::Value> thrown(aCx);
   // If we stored the original thrown JS value in the exception
   // (see XPCConvert::ConstructException) and we are in a web context
   // (i.e., not chrome), rethrow the original value. This only applies to JS
   // implemented components so we only need to check for this on the main
   // thread.
   if (NS_IsMainThread() && !IsCallerChrome() &&
       aException->StealJSVal(thrown.address())) {
     if (!JS_WrapValue(aCx, &thrown)) {
       return false;
     }
     JS_SetPendingException(aCx, thrown);
     return true;
   }
   JS::Rooted<JSObject*> glob(aCx, JS::CurrentGlobalOrNull(aCx));
   if (!glob) {
     // XXXbz Can this actually be null here?
     return false;
   }
   if (!WrapNewBindingObject(aCx, aException, &thrown)) {
     return false;
   }
   JS_SetPendingException(aCx, thrown);
   return true;
 }
 bool
 Throw(JSContext* aCx, nsresult aRv, const char* aMessage)
 {
   if (JS_IsExceptionPending(aCx)) {
     // Don't clobber the existing exception.
     return false;
   }
   CycleCollectedJSRuntime* runtime = CycleCollectedJSRuntime::Get();
   nsCOMPtr<nsIException> existingException = runtime->GetPendingException();
   if (existingException) {
     nsresult nr;
     if (NS_SUCCEEDED(existingException->GetResult(&nr)) &&
         aRv == nr) {
       // Reuse the existing exception.
       // Clear pending exception
       runtime->SetPendingException(nullptr);
       if (!ThrowExceptionObject(aCx, existingException)) {
         // If we weren't able to throw an exception we're
         // most likely out of memory
         JS_ReportOutOfMemory(aCx);
       }
       return false;
     }
   }
   nsRefPtr<Exception> finalException = CreateException(aCx, aRv, aMessage);
   MOZ_ASSERT(finalException);
   if (!ThrowExceptionObject(aCx, finalException)) {
     // If we weren't able to throw an exception we're
     // most likely out of memory
     JS_ReportOutOfMemory(aCx);
   }
   return false;
 }
 already_AddRefed<Exception>
 CreateException(JSContext* aCx, nsresult aRv, const char* aMessage)
 {
   // Do we use DOM exceptions for this error code?
   switch (NS_ERROR_GET_MODULE(aRv)) {
   case NS_ERROR_MODULE_DOM:
   case NS_ERROR_MODULE_SVG:
   case NS_ERROR_MODULE_DOM_XPATH:
   case NS_ERROR_MODULE_DOM_INDEXEDDB:
   case NS_ERROR_MODULE_DOM_FILEHANDLE:
     return DOMException::Create(aRv);
   default:
     break;
   }
   // If not, use the default.
   // aMessage can be null, so we can't use nsDependentCString on it.
   nsRefPtr<Exception> exception =
     new Exception(nsCString(aMessage), aRv,
                   EmptyCString(), nullptr, nullptr);
   return exception.forget();
 }
 already_AddRefed<nsIStackFrame>
 GetCurrentJSStack()
 {
   // is there a current context available?
   JSContext* cx = nullptr;
   if (NS_IsMainThread()) {
     // Note, in xpcshell nsContentUtils is never initialized, but we still need
     // to report exceptions.
     if (nsContentUtils::XPConnect()) {
       cx = nsContentUtils::XPConnect()->GetCurrentJSContext();
     } else {
       nsCOMPtr<nsIXPConnect> xpc = do_GetService(nsIXPConnect::GetCID());
       cx = xpc->GetCurrentJSContext();
     }
   } else {
     cx = workers::GetCurrentThreadJSContext();
   }
   if (!cx) {
     return nullptr;
   }
   nsCOMPtr<nsIStackFrame> stack = exceptions::CreateStack(cx);
   if (!stack) {
     return nullptr;
   }
   // peel off native frames...
   uint32_t language;
   nsCOMPtr<nsIStackFrame> caller;
   while (stack &&
          NS_SUCCEEDED(stack->GetLanguage(&language)) &&
          language != nsIProgrammingLanguage::JAVASCRIPT &&
          NS_SUCCEEDED(stack->GetCaller(getter_AddRefs(caller))) &&
          caller) {
     stack = caller;
   }
   return stack.forget();
 }
 namespace exceptions {
 class StackDescriptionOwner {
 public:
   StackDescriptionOwner(JS::StackDescription* aDescription)
     : mDescription(aDescription)
   {
     mozilla::HoldJSObjects(this);
   }
   ~StackDescriptionOwner()
   {
     // Make sure to set mDescription to null before calling DropJSObjects, since
     // in debug builds DropJSObjects try to trace us and we don't want to trace
     // a dead StackDescription.
     if (mDescription) {
       JS::FreeStackDescription(nullptr, mDescription);
       mDescription = nullptr;
     }
     mozilla::DropJSObjects(this);
   }
   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(StackDescriptionOwner)
   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_NATIVE_CLASS(StackDescriptionOwner)
   JS::FrameDescription& FrameAt(size_t aIndex)
   {
     MOZ_ASSERT(aIndex < mDescription->nframes);
     return mDescription->frames[aIndex];
   }
   unsigned NumFrames()
   {
     return mDescription->nframes;
   }
 private:
   JS::StackDescription* mDescription;
 };
 NS_IMPL_CYCLE_COLLECTION_ROOT_NATIVE(StackDescriptionOwner, AddRef)
 NS_IMPL_CYCLE_COLLECTION_UNROOT_NATIVE(StackDescriptionOwner, Release)
 NS_IMPL_CYCLE_COLLECTION_CLASS(StackDescriptionOwner)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(StackDescriptionOwner)
   if (tmp->mDescription) {
     JS::FreeStackDescription(nullptr, tmp->mDescription);
     tmp->mDescription = nullptr;
   }
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(StackDescriptionOwner)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(StackDescriptionOwner)
   JS::StackDescription* desc = tmp->mDescription;
   if (tmp->mDescription) {
     for (size_t i = 0; i < desc->nframes; ++i) {
       NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mDescription->frames[i].markedLocation1());
       NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mDescription->frames[i].markedLocation2());
     }
   }
 NS_IMPL_CYCLE_COLLECTION_TRACE_END
 class JSStackFrame : public nsIStackFrame
 {
 public:
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_CLASS(JSStackFrame)
   NS_DECL_NSISTACKFRAME
   // A null aStackDescription or an aIndex that's out of range for the
   // number of frames aStackDescription has will mean that the
   // JSStackFrame will never look at the stack description.  Instead,
   // it is expected to be initialized by the caller as needed.
   JSStackFrame(StackDescriptionOwner* aStackDescription, size_t aIndex);
   virtual ~JSStackFrame();
   static already_AddRefed<nsIStackFrame>
   CreateStack(JSContext* aCx, int32_t aMaxDepth = -1);
   static already_AddRefed<nsIStackFrame>
   CreateStackFrameLocation(uint32_t aLanguage,
                            const char* aFilename,
                            const char* aFunctionName,
                            int32_t aLineNumber,
                            nsIStackFrame* aCaller);
 private:
   bool IsJSFrame() const {
     return mLanguage == nsIProgrammingLanguage::JAVASCRIPT;
   }
   int32_t GetLineno();
   nsRefPtr<StackDescriptionOwner> mStackDescription;
   nsCOMPtr<nsIStackFrame> mCaller;
   // Cached values
   nsString mFilename;
   nsString mFunname;
   int32_t mLineno;
   uint32_t mLanguage;
   size_t mIndex;
   bool mFilenameInitialized;
   bool mFunnameInitialized;
   bool mLinenoInitialized;
   bool mCallerInitialized;
 };
 JSStackFrame::JSStackFrame(StackDescriptionOwner* aStackDescription,
                            size_t aIndex)
   : mLineno(0)
 {
   if (aStackDescription && aIndex < aStackDescription->NumFrames()) {
     mStackDescription = aStackDescription;
     mIndex = aIndex;
     mFilenameInitialized = false;
     mFunnameInitialized = false;
     mLinenoInitialized = false;
     mCallerInitialized = false;
     mLanguage = nsIProgrammingLanguage::JAVASCRIPT;
   } else {
     MOZ_ASSERT(!mStackDescription);
     mIndex = 0;
     mFilenameInitialized = true;
     mFunnameInitialized = true;
     mLinenoInitialized = true;
     mCallerInitialized = true;
     mLanguage = nsIProgrammingLanguage::UNKNOWN;
   }
 }
 JSStackFrame::~JSStackFrame()
 {
 }
 NS_IMPL_CYCLE_COLLECTION(JSStackFrame, mStackDescription, mCaller)
 NS_IMPL_CYCLE_COLLECTING_ADDREF(JSStackFrame)
 NS_IMPL_CYCLE_COLLECTING_RELEASE(JSStackFrame)
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(JSStackFrame)
   NS_INTERFACE_MAP_ENTRY(nsIStackFrame)
   NS_INTERFACE_MAP_ENTRY(nsISupports)
 NS_INTERFACE_MAP_END
 /* readonly attribute uint32_t language; */
 NS_IMETHODIMP JSStackFrame::GetLanguage(uint32_t* aLanguage)
 {
   *aLanguage = mLanguage;
   return NS_OK;
 }
 /* readonly attribute string languageName; */
 NS_IMETHODIMP JSStackFrame::GetLanguageName(nsACString& aLanguageName)
 {
   static const char js[] = "JavaScript";
   static const char cpp[] = "C++";
   if (IsJSFrame()) {
     aLanguageName.AssignASCII(js);
   } else {
     aLanguageName.AssignASCII(cpp);
   }
   return NS_OK;
 }
 /* readonly attribute AString filename; */
 NS_IMETHODIMP JSStackFrame::GetFilename(nsAString& aFilename)
 {
   if (!mFilenameInitialized) {
     JS::FrameDescription& desc = mStackDescription->FrameAt(mIndex);
     if (const char *filename = desc.filename()) {
       CopyUTF8toUTF16(filename, mFilename);
     }
     mFilenameInitialized = true;
   }
   // The filename must be set to null if empty.
   if (mFilename.IsEmpty()) {
     aFilename.SetIsVoid(true);
   } else {
     aFilename.Assign(mFilename);
   }
   return NS_OK;
 }
 /* readonly attribute AString name; */
 NS_IMETHODIMP JSStackFrame::GetName(nsAString& aFunction)
 {
   if (!mFunnameInitialized) {
     JS::FrameDescription& desc = mStackDescription->FrameAt(mIndex);
     if (JSFlatString *name = desc.funDisplayName()) {
       mFunname.Assign(JS_GetFlatStringChars(name),
                       // XXXbz Can't JS_GetStringLength on JSFlatString!
                       JS_GetStringLength(JS_FORGET_STRING_FLATNESS(name)));
     }
     mFunnameInitialized = true;
   }
   // The function name must be set to null if empty.
   if (mFunname.IsEmpty()) {
     aFunction.SetIsVoid(true);
   } else {
     aFunction.Assign(mFunname);
   }
   return NS_OK;
 }
 int32_t
 JSStackFrame::GetLineno()
 {
   if (!mLinenoInitialized) {
     JS::FrameDescription& desc = mStackDescription->FrameAt(mIndex);
     mLineno = desc.lineno();
     mLinenoInitialized = true;
   }
   return mLineno;
 }
 /* readonly attribute int32_t lineNumber; */
 NS_IMETHODIMP JSStackFrame::GetLineNumber(int32_t* aLineNumber)
 {
   *aLineNumber = GetLineno();
   return NS_OK;
 }
 /* readonly attribute AUTF8String sourceLine; */
 NS_IMETHODIMP JSStackFrame::GetSourceLine(nsACString& aSourceLine)
 {
   aSourceLine.Truncate();
   return NS_OK;
 }
 /* readonly attribute nsIStackFrame caller; */
 NS_IMETHODIMP JSStackFrame::GetCaller(nsIStackFrame** aCaller)
 {
   if (!mCallerInitialized) {
     mCaller = new JSStackFrame(mStackDescription, mIndex+1);
     mCallerInitialized = true;
   }
   NS_IF_ADDREF(*aCaller = mCaller);
   return NS_OK;
 }
 /* AUTF8String toString (); */
 NS_IMETHODIMP JSStackFrame::ToString(nsACString& _retval)
 {
   _retval.Truncate();
   const char* frametype = IsJSFrame() ? "JS" : "native";
   nsString filename;
   nsresult rv = GetFilename(filename);
   NS_ENSURE_SUCCESS(rv, rv);
   if (filename.IsEmpty()) {
     filename.AssignLiteral("<unknown filename>");
   }
   nsString funname;
   rv = GetName(funname);
   NS_ENSURE_SUCCESS(rv, rv);
   if (funname.IsEmpty()) {
     funname.AssignLiteral("<TOP_LEVEL>");
   }
   static const char format[] = "%s frame :: %s :: %s :: line %d";
   _retval.AppendPrintf(format, frametype,
                        NS_ConvertUTF16toUTF8(filename).get(),
                        NS_ConvertUTF16toUTF8(funname).get(),
                        GetLineno());
   return NS_OK;
 }
 /* static */ already_AddRefed<nsIStackFrame>
 JSStackFrame::CreateStack(JSContext* aCx, int32_t aMaxDepth)
 {
   static const unsigned MAX_FRAMES = 100;
   if (aMaxDepth < 0) {
     aMaxDepth = MAX_FRAMES;
   }
   JS::StackDescription* desc = JS::DescribeStack(aCx, aMaxDepth);
   if (!desc) {
     return nullptr;
   }
   nsRefPtr<StackDescriptionOwner> descOwner = new StackDescriptionOwner(desc);
   nsRefPtr<JSStackFrame> first = new JSStackFrame(descOwner, 0);
   return first.forget();
 }
 /* static */ already_AddRefed<nsIStackFrame>
 JSStackFrame::CreateStackFrameLocation(uint32_t aLanguage,
                                        const char* aFilename,
                                        const char* aFunctionName,
                                        int32_t aLineNumber,
                                        nsIStackFrame* aCaller)
 {
   nsRefPtr<JSStackFrame> self = new JSStackFrame(nullptr, 0);
   self->mLanguage = aLanguage;
   self->mLineno = aLineNumber;
   CopyUTF8toUTF16(aFilename, self->mFilename);
   CopyUTF8toUTF16(aFunctionName, self->mFunname);
   self->mCaller = aCaller;
   return self.forget();
 }
 already_AddRefed<nsIStackFrame>
 CreateStack(JSContext* aCx, int32_t aMaxDepth)
 {
   return JSStackFrame::CreateStack(aCx, aMaxDepth);
 }
 already_AddRefed<nsIStackFrame>
 CreateStackFrameLocation(uint32_t aLanguage,
                          const char* aFilename,
                          const char* aFunctionName,
                          int32_t aLineNumber,
                          nsIStackFrame* aCaller)
 {
   return JSStackFrame::CreateStackFrameLocation(aLanguage, aFilename,
                                                 aFunctionName, aLineNumber,
                                                 aCaller);
 }
 } // namespace exceptions
 } // namespace dom
 } // namespace mozilla

The Tor Browser / annotate

dom/bindings/Exceptions.cpp@97036ab72558 (annotated)

dom/bindings/Exceptions.cpp