dom/bindings/ErrorIPCUtils.h

   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 file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef IPC_ErrorIPCUtils_h
   8 #define IPC_ErrorIPCUtils_h
   9
  10 #include <utility>
  11
  12 #include "ipc/EnumSerializer.h"
  13 #include "ipc/IPCMessageUtils.h"
  14 #include "mozilla/Assertions.h"
  15 #include "mozilla/ErrorResult.h"
  16
  17 namespace IPC {
  18
  19 template <>
  20 struct ParamTraits<mozilla::dom::ErrNum>
  21     : public ContiguousEnumSerializer<
  22           mozilla::dom::ErrNum, mozilla::dom::ErrNum(0),
  23           mozilla::dom::ErrNum(mozilla::dom::Err_Limit)> {};
  24
  25 template <>
  26 struct ParamTraits<mozilla::ErrorResult> {
  27   typedef mozilla::ErrorResult paramType;
  28
  29   static void Write(MessageWriter* aWriter, const paramType& aParam) {
  30     // It should be the case that mMightHaveUnreportedJSException can only be
  31     // true when we're expecting a JS exception.  We cannot send such messages
  32     // over the IPC channel since there is no sane way of transferring the JS
  33     // value over to the other side.  Callers should never do that.
  34     MOZ_ASSERT_IF(aParam.IsJSException(),
  35                   aParam.mMightHaveUnreportedJSException);
  36     if (aParam.IsJSException()
  37 #ifdef DEBUG
  38         || aParam.mMightHaveUnreportedJSException
  39 #endif
  40     ) {
  41       MOZ_CRASH(
  42           "Cannot encode an ErrorResult representing a Javascript exception");
  43     }
  44
  45     WriteParam(aWriter, aParam.mResult);
  46     WriteParam(aWriter, aParam.IsErrorWithMessage());
  47     WriteParam(aWriter, aParam.IsDOMException());
  48     if (aParam.IsErrorWithMessage()) {
  49       aParam.SerializeMessage(aWriter);
  50     } else if (aParam.IsDOMException()) {
  51       aParam.SerializeDOMExceptionInfo(aWriter);
  52     }
  53   }
  54
  55   static void Write(MessageWriter* aWriter, paramType&& aParam) {
  56     Write(aWriter, static_cast<const paramType&>(aParam));
  57     aParam.SuppressException();
  58   }
  59
  60   static bool Read(MessageReader* aReader, paramType* aResult) {
  61     paramType readValue;
  62     if (!ReadParam(aReader, &readValue.mResult)) {
  63       return false;
  64     }
  65     bool hasMessage = false;
  66     if (!ReadParam(aReader, &hasMessage)) {
  67       return false;
  68     }
  69     bool hasDOMExceptionInfo = false;
  70     if (!ReadParam(aReader, &hasDOMExceptionInfo)) {
  71       return false;
  72     }
  73     if (hasMessage && hasDOMExceptionInfo) {
  74       // Shouldn't have both!
  75       return false;
  76     }
  77     if (hasMessage && !readValue.DeserializeMessage(aReader)) {
  78       return false;
  79     } else if (hasDOMExceptionInfo &&
  80                !readValue.DeserializeDOMExceptionInfo(aReader)) {
  81       return false;
  82     }
  83     *aResult = std::move(readValue);
  84     return true;
  85   }
  86 };
  87
  88 template <>
  89 struct ParamTraits<mozilla::CopyableErrorResult> {
  90   typedef mozilla::CopyableErrorResult paramType;
  91
  92   static void Write(MessageWriter* aWriter, const paramType& aParam) {
  93     ParamTraits<mozilla::ErrorResult>::Write(aWriter, aParam);
  94   }
  95
  96   static bool Read(MessageReader* aReader, paramType* aResult) {
  97     // We can't cast *aResult to ErrorResult&, so cheat and just cast
  98     // to ErrorResult*.
  99     return ParamTraits<mozilla::ErrorResult>::Read(
 100         aReader, reinterpret_cast<mozilla::ErrorResult*>(aResult));
 101   }
 102 };
 103
 104 }  // namespace IPC
 105
 106 #endif