1 // Copyright 2014 The Chromium Authors
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
9 #include <stdint.h>
10 #include <winioctl.h>
11
12 #include "base/base_paths.h"
13 #include "base/files/file_path.h"
14 #include "base/notreached.h"
15 #include "base/path_service.h"
16 #include "base/threading/scoped_blocking_call.h"
17 #include "base/win/scoped_handle.h"
18
19 namespace metrics {
20
21 // static
HasId()22 bool MachineIdProvider::HasId() {
23 return true;
24 }
25
26 // On windows, the machine id is based on the serial number of the drive Chrome
27 // is running from.
28 // static
GetMachineId()29 std::string MachineIdProvider::GetMachineId() {
30 base::ScopedBlockingCall scoped_blocking_call(FROM_HERE,
31 base::BlockingType::MAY_BLOCK);
32
33 // Use the program's path to get the drive used for the machine id. This means
34 // that whenever the underlying drive changes, it's considered a new machine.
35 // This is fine as we do not support migrating Chrome installs to new drives.
36 base::FilePath executable_path;
37
38 CHECK(base::PathService::Get(base::FILE_EXE, &executable_path));
39
40 std::vector<base::FilePath::StringType> path_components =
41 executable_path.GetComponents();
42 CHECK(!path_components.empty());
43 base::FilePath::StringType drive_name = L"\\\\.\\" + path_components[0];
44
45 base::win::ScopedHandle drive_handle(
46 CreateFile(drive_name.c_str(), 0, FILE_SHARE_READ | FILE_SHARE_WRITE,
47 nullptr, OPEN_EXISTING, 0, nullptr));
48
49 STORAGE_PROPERTY_QUERY query = {};
50 query.PropertyId = StorageDeviceProperty;
51 query.QueryType = PropertyStandardQuery;
52
53 // Perform an initial query to get the number of bytes being returned.
54 DWORD bytes_returned;
55 STORAGE_DESCRIPTOR_HEADER header = {};
56 BOOL status = DeviceIoControl(
57 drive_handle.Get(), IOCTL_STORAGE_QUERY_PROPERTY, &query,
58 sizeof(STORAGE_PROPERTY_QUERY), &header,
59 sizeof(STORAGE_DESCRIPTOR_HEADER), &bytes_returned, nullptr);
60
61 if (!status)
62 return std::string();
63
64 // Query for the actual serial number.
65 std::vector<int8_t> output_buf(header.Size);
66 status =
67 DeviceIoControl(drive_handle.Get(), IOCTL_STORAGE_QUERY_PROPERTY, &query,
68 sizeof(STORAGE_PROPERTY_QUERY), &output_buf[0],
69 output_buf.size(), &bytes_returned, nullptr);
70
71 if (!status)
72 return std::string();
73
74 const STORAGE_DEVICE_DESCRIPTOR* device_descriptor =
75 reinterpret_cast<STORAGE_DEVICE_DESCRIPTOR*>(&output_buf[0]);
76
77 // The serial number is stored in the |output_buf| as a null-terminated
78 // string starting at the specified offset.
79 const DWORD offset = device_descriptor->SerialNumberOffset;
80 if (offset >= output_buf.size())
81 return std::string();
82
83 // Make sure that the null-terminator exists.
84 const std::vector<int8_t>::iterator serial_number_begin =
85 output_buf.begin() + offset;
86 const std::vector<int8_t>::iterator null_location =
87 std::find(serial_number_begin, output_buf.end(), '\0');
88 if (null_location == output_buf.end())
89 return std::string();
90
91 const char* serial_number =
92 reinterpret_cast<const char*>(&output_buf[offset]);
93
94 return std::string(serial_number);
95 }
96 } // namespace metrics
97