Use udev for serial device enumeration on Linux

device/serial/serial_device_enumerator_linux.cc

+// Copyright (c) 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_linux.h"
+
+#include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
+
+namespace device {
+
+namespace {
+
+const char kSerialSubsystem[] = "tty";
+
+const char kHostPathKey[] = "DEVNAME";
+const char kHostBusKey[] = "ID_BUS";
+const char kVendorIDKey[] = "ID_VENDOR_ID";
+const char kProductIDKey[] = "ID_MODEL_ID";
+const char kProductNameKey[] = "ID_MODEL";
+
+struct UdevEnumerateDeleter {
+  void operator()(udev_enumerate* enumerate) {
+    udev_enumerate_unref(enumerate);
+  }
+};
+
+struct UdevDeviceDeleter {
+  void operator()(udev_device* device) {
+    udev_device_unref(device);
+  }
+};
+
+typedef scoped_ptr<udev_enumerate, UdevEnumerateDeleter> ScopedUdevEnumeratePtr;
+typedef scoped_ptr<udev_device, UdevDeviceDeleter> ScopedUdevDevicePtr;
+
+}
+
+// static
+scoped_ptr<SerialDeviceEnumerator> SerialDeviceEnumerator::Create() {
+  return scoped_ptr<SerialDeviceEnumerator>(new SerialDeviceEnumeratorLinux());
+}
+
+SerialDeviceEnumeratorLinux::SerialDeviceEnumeratorLinux() {
+  udev_.reset(udev_new());
+}
+
+SerialDeviceEnumeratorLinux::~SerialDeviceEnumeratorLinux() {
+}
+
+void SerialDeviceEnumeratorLinux::GetDevices(
+    std::vector<SerialDeviceInfo>* devices) {
+  devices->clear();
+
+  ScopedUdevEnumeratePtr enumerate(udev_enumerate_new(udev_.get()));
+  if (!enumerate) {
+    LOG(ERROR) << "Serial device enumeration failed.";
+    return;
+  }
+  if (udev_enumerate_add_match_subsystem(enumerate.get(), kSerialSubsystem)) {
+    LOG(ERROR) << "Serial device enumeration failed.";
+    return;
+  }
+  if (udev_enumerate_scan_devices(enumerate.get())) {
+    LOG(ERROR) << "Serial device enumeration failed.";
+    return;
+  }
+
+  udev_list_entry* entry = udev_enumerate_get_list_entry(enumerate.get());
+  for (; entry != NULL; entry = udev_list_entry_get_next(entry)) {
+    ScopedUdevDevicePtr device(
+        udev_device_new_from_syspath(
+            udev_.get(), udev_list_entry_get_name(entry)));
+    // TODO(rockot): There may be a better way to filter serial devices here,
+    // but it's not clear what that would be. Udev will list lots of virtual
+    // devices with no real endpoint to back them anywhere. The presence of
+    // a bus identifier (e.g., "pci" or "usb") seems to be a good heuristic
+    // for detecting actual devices.
+    const char *path =
+        udev_device_get_property_value(device.get(), kHostPathKey);
+    const char *bus =
+        udev_device_get_property_value(device.get(), kHostBusKey);
+    if (path != NULL && bus != NULL) {
+      SerialDeviceInfo info;
+      info.path = std::string(path);
+
+      const char *vendor_id =
+          udev_device_get_property_value(device.get(), kVendorIDKey);
+      const char *product_id =
+          udev_device_get_property_value(device.get(), kProductIDKey);
+      const char *product_name =
+          udev_device_get_property_value(device.get(), kProductNameKey);
+
+      uint32 int_value;
+      if (vendor_id && base::HexStringToUInt(vendor_id, &int_value))
+        info.vendor_id = int_value;
+      if (product_id && base::HexStringToUInt(product_id, &int_value))
+        info.product_id = int_value;
+      if (product_name)
+        info.display_name = product_name;
+
+      devices->push_back(info);
+    }
+  }
+}
+
+void SerialDeviceEnumeratorLinux::UdevDeleter::operator()(udev* handle) {
+  udev_unref(handle);
+}
+
+}  // namespace device