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82df5a3cd4
Differential Revision: https://phabricator.services.mozilla.com/D19953 --HG-- extra : moz-landing-system : lando
102 lines
2.8 KiB
C++
102 lines
2.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* A type that can be sent without needing to make a copy during
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* serialization. In addition the receiver can take ownership of the
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* data to avoid having to make an additional copy. */
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#ifndef mozilla_ipc_ByteBuf_h
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#define mozilla_ipc_ByteBuf_h
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#include "ipc/IPCMessageUtils.h"
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namespace mozilla {
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namespace ipc {
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class ByteBuf final {
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friend struct IPC::ParamTraits<mozilla::ipc::ByteBuf>;
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public:
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bool Allocate(size_t aLength) {
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MOZ_ASSERT(mData == nullptr);
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mData = (uint8_t*)malloc(aLength);
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if (!mData) {
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return false;
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}
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mLen = aLength;
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mCapacity = aLength;
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return true;
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}
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ByteBuf() : mData(nullptr), mLen(0), mCapacity(0) {}
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ByteBuf(uint8_t* aData, size_t aLen, size_t aCapacity)
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: mData(aData), mLen(aLen), mCapacity(aCapacity) {}
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ByteBuf(const ByteBuf& aFrom) = delete;
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ByteBuf(ByteBuf&& aFrom)
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: mData(aFrom.mData), mLen(aFrom.mLen), mCapacity(aFrom.mCapacity) {
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aFrom.mData = nullptr;
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aFrom.mLen = 0;
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aFrom.mCapacity = 0;
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}
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ByteBuf& operator=(ByteBuf&& aFrom) {
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std::swap(mData, aFrom.mData);
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std::swap(mLen, aFrom.mLen);
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std::swap(mCapacity, aFrom.mCapacity);
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return *this;
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}
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~ByteBuf() { free(mData); }
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uint8_t* mData;
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size_t mLen;
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size_t mCapacity;
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};
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} // namespace ipc
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} // namespace mozilla
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namespace IPC {
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template <>
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struct ParamTraits<mozilla::ipc::ByteBuf> {
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typedef mozilla::ipc::ByteBuf paramType;
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// this is where we transfer the memory from the ByteBuf to IPDL, avoiding a
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// copy
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static void Write(Message* aMsg, paramType&& aParam) {
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WriteParam(aMsg, aParam.mLen);
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// hand over ownership of the buffer to the Message
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aMsg->WriteBytesZeroCopy(aParam.mData, aParam.mLen, aParam.mCapacity);
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aParam.mData = nullptr;
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aParam.mCapacity = 0;
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aParam.mLen = 0;
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}
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static bool Read(const Message* aMsg, PickleIterator* aIter,
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paramType* aResult) {
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// We make a copy from the BufferList so that we get a contigous result.
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// For users the can handle a non-contiguous result using ExtractBuffers
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// is an option, alternatively if the users don't need to take ownership of
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// the data they can use the removed FlattenBytes (bug 1297981)
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size_t length;
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return ReadParam(aMsg, aIter, &length) && aResult->Allocate(length) &&
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aMsg->ReadBytesInto(aIter, aResult->mData, length);
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}
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static void Log(const paramType& aParam, std::wstring* aLog) {
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aLog->append(L"(byte buf)");
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}
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};
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} // namespace IPC
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#endif // ifndef mozilla_ipc_Shmem_h
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