text: // Copyright (c) 2012 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include "base/pickle.h"
  
  #include <stdlib.h>
  
  #include <algorithm>  // for max()
  
  //------------------------------------------------------------------------------
  
  using base::char16;
  using base::string16;
  
  // static
  const int Pickle::kPayloadUnit = 64;
  
  static const size_t kCapacityReadOnly = static_cast<size_t>(-1);
  
  PickleIterator::PickleIterator(const Pickle& pickle)
      : payload_(pickle.payload()),
        read_index_(0),
        end_index_(pickle.payload_size()) {
  }
  
  template <typename Type>
  inline bool PickleIterator::ReadBuiltinType(Type* result) {
    const char* read_from = GetReadPointerAndAdvance<Type>();
    if (!read_from)
      return false;
    if (sizeof(Type) > sizeof(uint32))
      memcpy(result, read_from, sizeof(*result));
    else
      *result = *reinterpret_cast<const Type*>(read_from);
    return true;
  }
  
  inline void PickleIterator::Advance(size_t size) {
    size_t aligned_size = AlignInt(size, sizeof(uint32_t));
    if (end_index_ - read_index_ < aligned_size) {
      read_index_ = end_index_;
    } else {
      read_index_ += aligned_size;
    }
  }
  
  template<typename Type>
  inline const char* PickleIterator::GetReadPointerAndAdvance() {
    if (sizeof(Type) > end_index_ - read_index_) {
      read_index_ = end_index_;
      return NULL;
    }
    const char* current_read_ptr = payload_ + read_index_;
    Advance(sizeof(Type));
    return current_read_ptr;
  }
  
  const char* PickleIterator::GetReadPointerAndAdvance(int num_bytes) {
    if (num_bytes < 0 ||
        end_index_ - read_index_ < static_cast<size_t>(num_bytes)) {
      read_index_ = end_index_;
      return NULL;
    }
    const char* current_read_ptr = payload_ + read_index_;
    Advance(num_bytes);
    return current_read_ptr;
  }
  
  inline const char* PickleIterator::GetReadPointerAndAdvance(
      int num_elements,
      size_t size_element) {
    // Check for int32 overflow.
    int64 num_bytes = static_cast<int64>(num_elements) * size_element;
    int num_bytes32 = static_cast<int>(num_bytes);
    if (num_bytes != static_cast<int64>(num_bytes32))
      return NULL;
    return GetReadPointerAndAdvance(num_bytes32);
  }
  
  bool PickleIterator::ReadBool(bool* result) {
    return ReadBuiltinType(result);
  }
  
  bool PickleIterator::ReadInt(int* result) {
    return ReadBuiltinType(result);
  }
  
  bool PickleIterator::ReadLong(long* result) {
    return ReadBuiltinType(result);
  }
  
  bool PickleIterator::ReadUInt16(uint16* result) {
    return ReadBuiltinType(result);
  }
  
  bool PickleIterator::ReadUInt32(uint32* result) {
    return ReadBuiltinType(result);
  }
  
  bool PickleIterator::ReadInt64(int64* result) {
    return ReadBuiltinType(result);
  }
  
  bool PickleIterator::ReadUInt64(uint64* result) {
    return ReadBuiltinType(result);
  }
  
  bool PickleIterator::ReadSizeT(size_t* result) {
    // Always read size_t as a 64-bit value to ensure compatibility between 32-bit
    // and 64-bit processes.
    uint64 result_uint64 = 0;
    bool success = ReadBuiltinType(&result_uint64);
    *result = static_cast<size_t>(result_uint64);
    // Fail if the cast above truncates the value.
    return success && (*result == result_uint64);
  }
  
  bool PickleIterator::ReadFloat(float* result) {
    // crbug.com/315213
    // The source data may not be properly aligned, and unaligned float reads
    // cause SIGBUS on some ARM platforms, so force using memcpy to copy the data
    // into the result.
    const char* read_from = GetReadPointerAndAdvance<float>();
    if (!read_from)
      return false;
    memcpy(result, read_from, sizeof(*result));
    return true;
  }
  
  bool PickleIterator::ReadDouble(double* result) {
    // crbug.com/315213
    // The source data may not be properly aligned, and unaligned double reads
    // cause SIGBUS on some ARM platforms, so force using memcpy to copy the data
    // into the result.
    const char* read_from = GetReadPointerAndAdvance<double>();
    if (!read_from)
      return false;
    memcpy(result, read_from, sizeof(*result));
    return true;
  }
  
  bool PickleIterator::ReadString(std::string* result) {
    int len;
    if (!ReadInt(&len))
      return false;
    const char* read_from = GetReadPointerAndAdvance(len);
    if (!read_from)
      return false;
  
    result->assign(read_from, len);
    return true;
  }
  
  bool PickleIterator::ReadWString(std::wstring* result) {
    int len;
    if (!ReadInt(&len))
      return false;
    const char* read_from = GetReadPointerAndAdvance(len, sizeof(wchar_t));
    if (!read_from)
      return false;
  
    result->assign(reinterpret_cast<const wchar_t*>(read_from), len);
    return true;
  }
  
  bool PickleIterator::ReadString16(string16* result) {
    int len;
    if (!ReadInt(&len))
      return false;
    const char* read_from = GetReadPointerAndAdvance(len, sizeof(char16));
    if (!read_from)
      return false;
  
    result->assign(reinterpret_cast<const char16*>(read_from), len);
    return true;
  }
  
  bool PickleIterator::ReadData(const char** data, int* length) {
    *length = 0;
    *data = 0;
  
    if (!ReadInt(length))
      return false;
  
    return ReadBytes(data, *length);
  }
  
  bool PickleIterator::ReadBytes(const char** data, int length) {
    const char* read_from = GetReadPointerAndAdvance(length);
    if (!read_from)
      return false;
    *data = read_from;
    return true;
  }
  
  // Payload is uint32 aligned.
  
  Pickle::Pickle()
      : header_(NULL),
        header_size_(sizeof(Header)),
        capacity_after_header_(0),
        write_offset_(0) {
    Resize(kPayloadUnit);
    header_->payload_size = 0;
  }
  
  Pickle::Pickle(int header_size)
      : header_(NULL),
        header_size_(AlignInt(header_size, sizeof(uint32))),
        capacity_after_header_(0),
        write_offset_(0) {
    DCHECK_GE(static_cast<size_t>(header_size), sizeof(Header));
    DCHECK_LE(header_size, kPayloadUnit);
    Resize(kPayloadUnit);
    header_->payload_size = 0;
  }
  
  Pickle::Pickle(const char* data, int data_len)
      : header_(reinterpret_cast<Header*>(const_cast<char*>(data))),
        header_size_(0),
        capacity_after_header_(kCapacityReadOnly),
        write_offset_(0) {
    if (data_len >= static_cast<int>(sizeof(Header)))
      header_size_ = data_len - header_->payload_size;
  
    if (header_size_ > static_cast<unsigned int>(data_len))
      header_size_ = 0;
  
    if (header_size_ != AlignInt(header_size_, sizeof(uint32)))
      header_size_ = 0;
  
    // If there is anything wrong with the data, we're not going to use it.
    if (!header_size_)
      header_ = NULL;
  }
  
  Pickle::Pickle(const Pickle& other)
      : header_(NULL),
        header_size_(other.header_size_),
        capacity_after_header_(0),
        write_offset_(other.write_offset_) {
    size_t payload_size = header_size_ + other.header_->payload_size;
    Resize(payload_size);
    memcpy(header_, other.header_, payload_size);
  }
  
  Pickle::~Pickle() {
    if (capacity_after_header_ != kCapacityReadOnly)
      free(header_);
  }
  
  Pickle& Pickle::operator=(const Pickle& other) {
    if (this == &other) {
      NOTREACHED();
      return *this;
    }
    if (capacity_after_header_ == kCapacityReadOnly) {
      header_ = NULL;
      capacity_after_header_ = 0;
    }
    if (header_size_ != other.header_size_) {
      free(header_);
      header_ = NULL;
      header_size_ = other.header_size_;
    }
    Resize(other.header_->payload_size);
    memcpy(header_, other.header_,
           other.header_size_ + other.header_->payload_size);
    write_offset_ = other.write_offset_;
    return *this;
  }
  
  bool Pickle::WriteString(const std::string& value) {
    if (!WriteInt(static_cast<int>(value.size())))
      return false;
  
    return WriteBytes(value.data(), static_cast<int>(value.size()));
  }
  
  bool Pickle::WriteWString(const std::wstring& value) {
    if (!WriteInt(static_cast<int>(value.size())))
      return false;
  
    return WriteBytes(value.data(),
                      static_cast<int>(value.size() * sizeof(wchar_t)));
  }
  
  bool Pickle::WriteString16(const string16& value) {
    if (!WriteInt(static_cast<int>(value.size())))
      return false;
  
    return WriteBytes(value.data(),
                      static_cast<int>(value.size()) * sizeof(char16));
  }
  
  bool Pickle::WriteData(const char* data, int length) {
    return length >= 0 && WriteInt(length) && WriteBytes(data, length);
  }
  
  bool Pickle::WriteBytes(const void* data, int length) {
    WriteBytesCommon(data, length);
    return true;
  }
  
  void Pickle::Reserve(size_t length) {
    size_t data_len = AlignInt(length, sizeof(uint32));
    DCHECK_GE(data_len, length);
  #ifdef ARCH_CPU_64_BITS
    DCHECK_LE(data_len, kuint32max);
  #endif
    DCHECK_LE(write_offset_, kuint32max - data_len);
    size_t new_size = write_offset_ + data_len;
    if (new_size > capacity_after_header_)
      Resize(capacity_after_header_ * 2 + new_size);
  }
  
  void Pickle::Resize(size_t new_capacity) {
    new_capacity = AlignInt(new_capacity, kPayloadUnit);
  
    CHECK_NE(capacity_after_header_, kCapacityReadOnly);
    void* p = realloc(header_, header_size_ + new_capacity);
    CHECK(p);
    header_ = reinterpret_cast<Header*>(p);
    capacity_after_header_ = new_capacity;
  }
  
  // static
  const char* Pickle::FindNext(size_t header_size,
                               const char* start,
                               const char* end) {
    DCHECK_EQ(header_size, AlignInt(header_size, sizeof(uint32)));
    DCHECK_LE(header_size, static_cast<size_t>(kPayloadUnit));
  
    size_t length = static_cast<size_t>(end - start);
    if (length < sizeof(Header))
      return NULL;
  
    const Header* hdr = reinterpret_cast<const Header*>(start);
    if (length < header_size || length - header_size < hdr->payload_size)
      return NULL;
    return start + header_size + hdr->payload_size;
  }
  
  template <size_t length> void Pickle::WriteBytesStatic(const void* data) {
    WriteBytesCommon(data, length);
  }
  
  template void Pickle::WriteBytesStatic<2>(const void* data);
  template void Pickle::WriteBytesStatic<4>(const void* data);
  template void Pickle::WriteBytesStatic<8>(const void* data);
  
  inline void Pickle::WriteBytesCommon(const void* data, size_t length) {
    DCHECK_NE(kCapacityReadOnly, capacity_after_header_)
        << "oops: pickle is readonly";
    size_t data_len = AlignInt(length, sizeof(uint32));
    DCHECK_GE(data_len, length);
  #ifdef ARCH_CPU_64_BITS
    DCHECK_LE(data_len, kuint32max);
  #endif
    DCHECK_LE(write_offset_, kuint32max - data_len);
    size_t new_size = write_offset_ + data_len;
    if (new_size > capacity_after_header_) {
      Resize(std::max(capacity_after_header_ * 2, new_size));
    }
  
    char* write = mutable_payload() + write_offset_;
    memcpy(write, data, length);
    memset(write + length, 0, data_len - length);
    header_->payload_size = static_cast<uint32>(new_size);
    write_offset_ = new_size;
  }
  