The Tor Browser: dom/bindings/ErrorResult.h@97036ab72558 (annotated)

dom/bindings/ErrorResult.h@97036ab72558 (annotated)

dom/bindings/ErrorResult.h

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 -*-*/
 /* vim: set ts=2 sw=2 et tw=79: */
 /* 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/. */
 /**
  * A struct for tracking exceptions that need to be thrown to JS.
  */
 #ifndef mozilla_ErrorResult_h
 #define mozilla_ErrorResult_h
 #include <stdarg.h>
 #include "js/Value.h"
 #include "nscore.h"
 #include "nsStringGlue.h"
 #include "mozilla/Assertions.h"
 namespace mozilla {
 namespace dom {
 enum ErrNum {
 #define MSG_DEF(_name, _argc, _str) \
   _name,
 #include "mozilla/dom/Errors.msg"
 #undef MSG_DEF
   Err_Limit
 };
 bool
 ThrowErrorMessage(JSContext* aCx, const ErrNum aErrorNumber, ...);
 } // namespace dom
 class ErrorResult {
 public:
   ErrorResult() {
     mResult = NS_OK;
 #ifdef DEBUG
     // ErrorResult is extremely performance-sensitive code, where literally
     // every machine instruction matters. Initialize mMessage only to suppress
     // a debug-only warning from gcc 4.6.
     mMessage = nullptr;
     mMightHaveUnreportedJSException = false;
 #endif
   }
 #ifdef DEBUG
   ~ErrorResult() {
     MOZ_ASSERT_IF(IsTypeError(), !mMessage);
     MOZ_ASSERT(!mMightHaveUnreportedJSException);
   }
 #endif
   void Throw(nsresult rv) {
     MOZ_ASSERT(NS_FAILED(rv), "Please don't try throwing success");
     MOZ_ASSERT(rv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");
     MOZ_ASSERT(!IsTypeError(), "Don't overwite TypeError");
     MOZ_ASSERT(rv != NS_ERROR_DOM_JS_EXCEPTION, "Use ThrowJSException()");
     MOZ_ASSERT(!IsJSException(), "Don't overwrite JS exceptions");
     MOZ_ASSERT(rv != NS_ERROR_XPC_NOT_ENOUGH_ARGS, "Use ThrowNotEnoughArgsError()");
     MOZ_ASSERT(!IsNotEnoughArgsError(), "Don't overwrite not enough args error");
     mResult = rv;
   }
   void ThrowTypeError(const dom::ErrNum errorNumber, ...);
   void ReportTypeError(JSContext* cx);
   void ClearMessage();
   bool IsTypeError() const { return ErrorCode() == NS_ERROR_TYPE_ERR; }
   // Facilities for throwing a preexisting JS exception value via this
   // ErrorResult.  The contract is that any code which might end up calling
   // ThrowJSException() must call MightThrowJSException() even if no exception
   // is being thrown.  Code that would call ReportJSException* or
   // StealJSException as needed must first call WouldReportJSException even if
   // this ErrorResult has not failed.
   //
   // The exn argument to ThrowJSException can be in any compartment.  It does
   // not have to be in the compartment of cx.  If someone later uses it, they
   // will wrap it into whatever compartment they're working in, as needed.
   void ThrowJSException(JSContext* cx, JS::Handle<JS::Value> exn);
   void ReportJSException(JSContext* cx);
   // Used to implement throwing exceptions from the JS implementation of
   // bindings to callers of the binding.
   void ReportJSExceptionFromJSImplementation(JSContext* aCx);
   bool IsJSException() const { return ErrorCode() == NS_ERROR_DOM_JS_EXCEPTION; }
   void ThrowNotEnoughArgsError() { mResult = NS_ERROR_XPC_NOT_ENOUGH_ARGS; }
   void ReportNotEnoughArgsError(JSContext* cx,
                                 const char* ifaceName,
                                 const char* memberName);
   bool IsNotEnoughArgsError() const { return ErrorCode() == NS_ERROR_XPC_NOT_ENOUGH_ARGS; }
   // StealJSException steals the JS Exception from the object. This method must
   // be called only if IsJSException() returns true. This method also resets the
   // ErrorCode() to NS_OK.
   void StealJSException(JSContext* cx, JS::MutableHandle<JS::Value> value);
   void MOZ_ALWAYS_INLINE MightThrowJSException()
   {
 #ifdef DEBUG
     mMightHaveUnreportedJSException = true;
 #endif
   }
   void MOZ_ALWAYS_INLINE WouldReportJSException()
   {
 #ifdef DEBUG
     mMightHaveUnreportedJSException = false;
 #endif
   }
   // In the future, we can add overloads of Throw that take more
   // interesting things, like strings or DOM exception types or
   // something if desired.
   // Backwards-compat to make conversion simpler.  We don't call
   // Throw() here because people can easily pass success codes to
   // this.
   void operator=(nsresult rv) {
     MOZ_ASSERT(rv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");
     MOZ_ASSERT(!IsTypeError(), "Don't overwite TypeError");
     MOZ_ASSERT(rv != NS_ERROR_DOM_JS_EXCEPTION, "Use ThrowJSException()");
     MOZ_ASSERT(!IsJSException(), "Don't overwrite JS exceptions");
     MOZ_ASSERT(rv != NS_ERROR_XPC_NOT_ENOUGH_ARGS, "Use ThrowNotEnoughArgsError()");
     MOZ_ASSERT(!IsNotEnoughArgsError(), "Don't overwrite not enough args error");
     mResult = rv;
   }
   bool Failed() const {
     return NS_FAILED(mResult);
   }
   nsresult ErrorCode() const {
     return mResult;
   }
 private:
   nsresult mResult;
   struct Message;
   // mMessage is set by ThrowTypeError and cleared (and deallocatd) by
   // ReportTypeError.
   // mJSException is set (and rooted) by ThrowJSException and unrooted
   // by ReportJSException.
   union {
     Message* mMessage; // valid when IsTypeError()
     JS::Value mJSException; // valid when IsJSException()
   };
 #ifdef DEBUG
   // Used to keep track of codepaths that might throw JS exceptions,
   // for assertion purposes.
   bool mMightHaveUnreportedJSException;
 #endif
   // Not to be implemented, to make sure people always pass this by
   // reference, not by value.
   ErrorResult(const ErrorResult&) MOZ_DELETE;
 };
 /******************************************************************************
  ** Macros for checking results
  ******************************************************************************/
 #define ENSURE_SUCCESS(res, ret)                                          \
   do {                                                                    \
     if (res.Failed()) {                                                   \
       nsCString msg;                                                      \
       msg.AppendPrintf("ENSURE_SUCCESS(%s, %s) failed with "              \
                        "result 0x%X", #res, #ret, res.ErrorCode());       \
       NS_WARNING(msg.get());                                              \
       return ret;                                                         \
     }                                                                     \
   } while(0)
 #define ENSURE_SUCCESS_VOID(res)                                          \
   do {                                                                    \
     if (res.Failed()) {                                                   \
       nsCString msg;                                                      \
       msg.AppendPrintf("ENSURE_SUCCESS_VOID(%s) failed with "             \
                        "result 0x%X", #res, res.ErrorCode());             \
       NS_WARNING(msg.get());                                              \
       return;                                                             \
     }                                                                     \
   } while(0)
 } // namespace mozilla
 #endif /* mozilla_ErrorResult_h */

The Tor Browser / annotate

dom/bindings/ErrorResult.h@97036ab72558 (annotated)

dom/bindings/ErrorResult.h