text: // Copyright (c) 2009 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 <limits>
  #include <windows.h>
  
  #include "base/logging.h"
  #include "base/sys_info.h"
  #include "chrome/common/transport_dib.h"
  
  TransportDIB::TransportDIB() {
  }
  
  TransportDIB::~TransportDIB() {
  }
  
  TransportDIB::TransportDIB(HANDLE handle)
      : shared_memory_(handle, false /* read write */) {
  }
  
  // static
  TransportDIB* TransportDIB::Create(size_t size, uint32_t sequence_num) {
    size_t allocation_granularity = base::SysInfo::VMAllocationGranularity();
    size = size / allocation_granularity + 1;
    size = size * allocation_granularity;
  
    TransportDIB* dib = new TransportDIB;
  
    if (!dib->shared_memory_.Create("", false /* read write */,
                                    true /* open existing */, size)) {
      delete dib;
      return NULL;
    }
  
    dib->size_ = size;
    dib->sequence_num_ = sequence_num;
  
    return dib;
  }
  
  // static
  TransportDIB* TransportDIB::Map(TransportDIB::Handle handle) {
    TransportDIB* dib = new TransportDIB(handle);
    if (!dib->shared_memory_.Map(0 /* map whole shared memory segment */)) {
      LOG(ERROR) << "Failed to map transport DIB"
                 << " handle:" << handle
                 << " error:" << GetLastError();
      delete dib;
      return NULL;
    }
  
    // There doesn't seem to be any way to find the size of the shared memory
    // region! GetFileSize indicates that the handle is invalid. Thus, we
    // conservatively set the size to the maximum and hope that the renderer
    // isn't about to ask us to read off the end of the array.
    dib->size_ = std::numeric_limits<size_t>::max();
  
    return dib;
  }
  
  void* TransportDIB::memory() const {
    return shared_memory_.memory();
  }
  
  TransportDIB::Handle TransportDIB::handle() const {
    return shared_memory_.handle();
  }
  
  TransportDIB::Id TransportDIB::id() const {
    return Id(shared_memory_.handle(), sequence_num_);
  }
  