components/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 "components/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/threading/thread_restrictions.h"
  14 #include "base/win/scoped_handle.h"
  15
  16 namespace metrics {
  17
  18 MachineIdProvider::MachineIdProvider() {
  19 }
  20
  21 MachineIdProvider::~MachineIdProvider() {
  22 }
  23
  24 // On windows, the machine id is based on the serial number of the drive Chrome
  25 // is running from.
  26 std::string MachineIdProvider::GetMachineId() {
  27   base::ThreadRestrictions::AssertIOAllowed();
  28
  29   // Use the program's path to get the drive used for the machine id. This means
  30   // that whenever the underlying drive changes, it's considered a new machine.
  31   // This is fine as we do not support migrating Chrome installs to new drives.
  32   base::FilePath executable_path;
  33
  34   if (!PathService::Get(base::FILE_EXE, &executable_path)) {
  35     NOTREACHED();
  36     return std::string();
  37   }
  38
  39   std::vector<base::FilePath::StringType> path_components;
  40   executable_path.GetComponents(&path_components);
  41   if (path_components.empty()) {
  42     NOTREACHED();
  43     return std::string();
  44   }
  45   base::FilePath::StringType drive_name = L"\\\\.\\" + path_components[0];
  46
  47   base::win::ScopedHandle drive_handle(
  48       CreateFile(drive_name.c_str(),
  49                  0,
  50                  FILE_SHARE_READ | FILE_SHARE_WRITE,
  51                  NULL,
  52                  OPEN_EXISTING,
  53                  0,
  54                  NULL));
  55
  56   STORAGE_PROPERTY_QUERY query = {};
  57   query.PropertyId = StorageDeviceProperty;
  58   query.QueryType = PropertyStandardQuery;
  59
  60   // Perform an initial query to get the number of bytes being returned.
  61   DWORD bytes_returned;
  62   STORAGE_DESCRIPTOR_HEADER header = {};
  63   BOOL status = DeviceIoControl(drive_handle.Get(),
  64                                 IOCTL_STORAGE_QUERY_PROPERTY,
  65                                 &query,
  66                                 sizeof(STORAGE_PROPERTY_QUERY),
  67                                 &header,
  68                                 sizeof(STORAGE_DESCRIPTOR_HEADER),
  69                                 &bytes_returned,
  70                                 NULL);
  71
  72   if (!status)
  73     return std::string();
  74
  75   // Query for the actual serial number.
  76   std::vector<int8> output_buf(header.Size);
  77   status = DeviceIoControl(drive_handle.Get(),
  78                            IOCTL_STORAGE_QUERY_PROPERTY,
  79                            &query,
  80                            sizeof(STORAGE_PROPERTY_QUERY),
  81                            &output_buf[0],
  82                            output_buf.size(),
  83                            &bytes_returned,
  84                            NULL);
  85
  86   if (!status)
  87     return std::string();
  88
  89   const STORAGE_DEVICE_DESCRIPTOR* device_descriptor =
  90       reinterpret_cast<STORAGE_DEVICE_DESCRIPTOR*>(&output_buf[0]);
  91
  92   // The serial number is stored in the |output_buf| as a null-terminated
  93   // string starting at the specified offset.
  94   const DWORD offset = device_descriptor->SerialNumberOffset;
  95   if (offset >= output_buf.size())
  96     return std::string();
  97
  98   // Make sure that the null-terminator exists.
  99   const std::vector<int8>::iterator serial_number_begin =
 100       output_buf.begin() + offset;
 101   const std::vector<int8>::iterator null_location =
 102       std::find(serial_number_begin, output_buf.end(), '\0');
 103   if (null_location == output_buf.end())
 104     return std::string();
 105
 106   const char* serial_number =
 107       reinterpret_cast<const char*>(&output_buf[offset]);
 108
 109   return std::string(serial_number);
 110 }
 111
 112 // static
 113 MachineIdProvider* MachineIdProvider::CreateInstance() {
 114   return new MachineIdProvider();
 115 }
 116
 117 }  //  namespace metrics