chrome/browser/metrics/machine_id_provider_win.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/metrics/machine_id_provider.h"
   6
   7 #include <windows.h>
   8 #include <winioctl.h>
   9
  10 #include "base/base_paths.h"
  11 #include "base/files/file_path.h"
  12 #include "base/path_service.h"
  13 #include "base/win/scoped_handle.h"
  14 #include "content/public/browser/browser_thread.h"
  15
  16 namespace metrics {
  17
  18 MachineIdProvider::MachineIdProvider() {}
  19 MachineIdProvider::~MachineIdProvider() {}
  20
  21 // On windows, the machine id is based on the serial number of the drive Chrome
  22 // is running from.
  23 std::string MachineIdProvider::GetMachineId() {
  24   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
  25
  26   // Use the program's path to get the drive used for the machine id. This means
  27   // that whenever the underlying drive changes, it's considered a new machine.
  28   // This is fine as we do not support migrating Chrome installs to new drives.
  29   base::FilePath executable_path;
  30
  31   if (!PathService::Get(base::FILE_EXE, &executable_path)) {
  32     NOTREACHED();
  33     return std::string();
  34   }
  35
  36   std::vector<base::FilePath::StringType> path_components;
  37   executable_path.GetComponents(&path_components);
  38   if (path_components.empty()) {
  39     NOTREACHED();
  40     return std::string();
  41   }
  42   base::FilePath::StringType drive_name = L"\\\\.\\" + path_components[0];
  43
  44   base::win::ScopedHandle drive_handle(CreateFile(
  45       drive_name.c_str(),
  46       0,
  47       FILE_SHARE_READ | FILE_SHARE_WRITE,
  48       NULL,
  49       OPEN_EXISTING,
  50       0,
  51       NULL));
  52
  53   STORAGE_PROPERTY_QUERY query = {};
  54   query.PropertyId = StorageDeviceProperty;
  55   query.QueryType = PropertyStandardQuery;
  56
  57   // Perform an initial query to get the number of bytes being returned.
  58   DWORD bytes_returned;
  59   STORAGE_DESCRIPTOR_HEADER header = {};
  60   BOOL status = DeviceIoControl(drive_handle, IOCTL_STORAGE_QUERY_PROPERTY,
  61                                 &query, sizeof(STORAGE_PROPERTY_QUERY),
  62                                 &header, sizeof(STORAGE_DESCRIPTOR_HEADER),
  63                                 &bytes_returned, NULL);
  64
  65   if (!status)
  66     return std::string();
  67
  68   // Query for the actual serial number.
  69   std::vector<int8> output_buf(header.Size);
  70   status = DeviceIoControl(drive_handle, IOCTL_STORAGE_QUERY_PROPERTY,
  71                            &query, sizeof(STORAGE_PROPERTY_QUERY),
  72                            &output_buf[0], output_buf.size(),
  73                            &bytes_returned, NULL);
  74
  75   if (!status)
  76     return std::string();
  77
  78   const STORAGE_DEVICE_DESCRIPTOR* device_descriptor =
  79       reinterpret_cast<STORAGE_DEVICE_DESCRIPTOR*>(&output_buf[0]);
  80
  81   // The serial number is stored in the |output_buf| as a null-terminated
  82   // string starting at the specified offset.
  83   const DWORD offset = device_descriptor->SerialNumberOffset;
  84   if (offset >= output_buf.size())
  85     return std::string();
  86
  87   // Make sure that the null-terminator exists.
  88   const std::vector<int8>::iterator serial_number_begin =
  89       output_buf.begin() + offset;
  90   const std::vector<int8>::iterator null_location =
  91       std::find(serial_number_begin, output_buf.end(), '\0');
  92   if (null_location == output_buf.end())
  93     return std::string();
  94
  95   const char* serial_number =
  96       reinterpret_cast<const char*>(&output_buf[offset]);
  97
  98   return std::string(serial_number);
  99 }
 100
 101 // static
 102 MachineIdProvider* MachineIdProvider::CreateInstance() {
 103   return new MachineIdProvider();
 104 }
 105
 106 } //  namespace metrics