Extracts more information from serial devices on Windows

device/serial/serial_device_enumerator_win.cc

 // Copyright 2014 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 "device/serial/serial_device_enumerator_win.h"
 
+// This has to be included before windows.h.
+#include "third_party/re2/re2/re2.h"
+
 #include <windows.h>
+#include <ntddser.h>
+#include <setupapi.h>
 
 #include "base/memory/scoped_ptr.h"
-#include "base/strings/string_util.h"
-#include "base/strings/stringprintf.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
-#include "base/win/registry.h"
 
 namespace device {
 
+namespace {
+
+// Searches the specified device info for a property with the specified key,
+// assigns the result to value, and returns whether the operation was
+// successful.
+bool GetProperty(HDEVINFO dev_info,
+                 SP_DEVINFO_DATA dev_info_data,
+                 const int key,
+                 std::string* value) {
+  // We don't know how much space the property's value will take up, so we call
+  // the property retrieval function once to fetch the size of the required
+  // value buffer, then again once we've allocated a sufficiently large buffer.
+  scoped_ptr<wchar_t[]> buffer;
+  DWORD buffer_size = 0;
+  while (!SetupDiGetDeviceRegistryProperty(dev_info, &dev_info_data, key, NULL,
+                                           (PBYTE)buffer.get(), buffer_size,

[Ken Rockot(use gerrit already), 2015/09/23 17:30:18]

buffer.get() is always nullptr here. Why not just use nullptr? Casting to PBYTE
should then be unnecessary too (and if not, please use static_cast instead of
C-style casts)

[charliea (OOO until 10-5), 2015/09/28 13:22:53]

Yea, the way that this was written with the while loop, it wasn't the clearest
what was happening. I uploaded a new patch that tries to clarify what I'm doing,
so PTAL.

Essentially, the first time through this loop, buffer is null and we expect to
receive an ERROR_INSUFFICIENT buffer, but the second time through, we pass in a
pointer to a sufficiently large buffer and the call should succeed. Just putting
NULL in the while loop condition would have meant that, in that second iteration
of the loop, we wouldn't have actually passed the buffer to the function, and
thus we wouldn't have pulled out the value we needed to.

Anyhow, all of this should hopefully be clearer in the new revision I uploaded.

+                                           &buffer_size)) {
+    if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
+      buffer.reset(new wchar_t[buffer_size]);
+    else
+      return false;
+  }
+
+  *value = base::WideToUTF8(buffer.get());
+  return true;
+}
+
+// Searches for the COM port in the device's friendly name, assigns its value to
+// com_port, and returns whether the operation was successful.
+bool GetCOMPort(const std::string friendly_name, std::string* com_port) {
+  return RE2::PartialMatch(friendly_name, ".* \\((COM[0-9]+)\\)", com_port);
+}
+
+// Searches for the display name in the device's friendly name, assigns its
+// value to display_name, and returns whether the operation was successful.
+bool GetDisplayName(const std::string friendly_name,
+                    std::string* display_name) {
+  return RE2::PartialMatch(friendly_name, "(.*) \\(COM[0-9]+\\)", display_name);
+}
+
+// Searches for the vendor ID in the device's hardware ID, assigns its value to
+// vendor_id, and returns whether the operation was successful.
+bool GetVendorID(const std::string hardware_id, uint32_t* vendor_id) {
+  std::string vendor_id_str;
+  return RE2::PartialMatch(hardware_id, "VID_([0-9]+)", &vendor_id_str) &&
+         base::HexStringToUInt(vendor_id_str, vendor_id);
+}
+
+// Searches for the product ID in the device's product ID, assigns its value to
+// product_id, and returns whether the operation was successful.
+bool GetProductID(const std::string hardware_id, uint32_t* product_id) {
+  std::string product_id_str;
+  return RE2::PartialMatch(hardware_id, "PID_([0-9]+)", &product_id_str) &&
+         base::HexStringToUInt(product_id_str, product_id);
+}
+
+}  // namespace
+
 // static
 scoped_ptr<SerialDeviceEnumerator> SerialDeviceEnumerator::Create() {
   return scoped_ptr<SerialDeviceEnumerator>(new SerialDeviceEnumeratorWin());
 }
 
 SerialDeviceEnumeratorWin::SerialDeviceEnumeratorWin() {}
 
 SerialDeviceEnumeratorWin::~SerialDeviceEnumeratorWin() {}
 
-// TODO(rockot): Query the system for more information than just device paths.
-// This may or may not require using a different strategy than scanning the
-// registry location below.
 mojo::Array<serial::DeviceInfoPtr> SerialDeviceEnumeratorWin::GetDevices() {
-  base::win::RegistryValueIterator iter_key(
-      HKEY_LOCAL_MACHINE, L"HARDWARE\\DEVICEMAP\\SERIALCOMM\\");
   mojo::Array<serial::DeviceInfoPtr> devices(0);
-  for (; iter_key.Valid(); ++iter_key) {
+
+  // Make a device interface query to find all serial devices.
+  HDEVINFO dev_info =
+      SetupDiGetClassDevs(&GUID_DEVINTERFACE_SERENUM_BUS_ENUMERATOR, 0, 0,
+                          DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
+  if (dev_info == INVALID_HANDLE_VALUE)
+    return devices.Pass();
+
+  SP_DEVINFO_DATA dev_info_data;
+  dev_info_data.cbSize = sizeof(SP_DEVINFO_DATA);
+  for (DWORD i = 0; SetupDiEnumDeviceInfo(dev_info, i, &dev_info_data); i++) {
+    std::string friendly_name, com_port;
+    // SPDRP_FRIENDLYNAME looks like "USB_SERIAL_PORT (COM3)".
+    if (!GetProperty(dev_info, dev_info_data, SPDRP_FRIENDLYNAME,
+                     &friendly_name) ||
+        !GetCOMPort(friendly_name, &com_port))
+      // In Windows, the COM port is the path used to uniquely identify the
+      // serial device. If the COM can't be found, ignore the device.
+      continue;
+
     serial::DeviceInfoPtr info(serial::DeviceInfo::New());
-    info->path = base::UTF16ToASCII(iter_key.Value());
+    info->path = com_port;
+
+    std::string display_name;
+    if (GetDisplayName(friendly_name, &display_name))
+      info->display_name = display_name;
+
+    std::string hardware_id;
+    // SPDRP_HARDWAREID looks like "FTDIBUS\COMPORT&VID_0403&PID_6001".
+    if (GetProperty(dev_info, dev_info_data, SPDRP_HARDWAREID, &hardware_id)) {
+      uint32_t vendor_id, product_id;
+      if (GetVendorID(hardware_id, &vendor_id)) {
+        info->has_vendor_id = true;
+        info->vendor_id = vendor_id;
+      }
+      if (GetProductID(hardware_id, &product_id)) {
+        info->has_product_id = true;
+        info->product_id = product_id;
+      }
+    }
+
     devices.push_back(info.Pass());
   }
+
+  SetupDiDestroyDeviceInfoList(dev_info);
   return devices.Pass();
 }
 
 }  // namespace device