text: // 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_linux.h"
  
  #include <stdint.h>
  #include <utility>
  
  #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";
  
  }  // namespace
  
  // static
  scoped_ptr<SerialDeviceEnumerator> SerialDeviceEnumerator::Create() {
    return scoped_ptr<SerialDeviceEnumerator>(new SerialDeviceEnumeratorLinux());
  }
  
  SerialDeviceEnumeratorLinux::SerialDeviceEnumeratorLinux() {
    udev_.reset(udev_new());
  }
  
  SerialDeviceEnumeratorLinux::~SerialDeviceEnumeratorLinux() {}
  
  mojo::Array<serial::DeviceInfoPtr> SerialDeviceEnumeratorLinux::GetDevices() {
    mojo::Array<serial::DeviceInfoPtr> devices(0);
    ScopedUdevEnumeratePtr enumerate(udev_enumerate_new(udev_.get()));
    if (!enumerate) {
      LOG(ERROR) << "Serial device enumeration failed.";
      return devices;
    }
    if (udev_enumerate_add_match_subsystem(enumerate.get(), kSerialSubsystem)) {
      LOG(ERROR) << "Serial device enumeration failed.";
      return devices;
    }
    if (udev_enumerate_scan_devices(enumerate.get())) {
      LOG(ERROR) << "Serial device enumeration failed.";
      return devices;
    }
  
    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) {
        serial::DeviceInfoPtr info(serial::DeviceInfo::New());
        info->path = 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_t int_value;
        if (vendor_id && base::HexStringToUInt(vendor_id, &int_value)) {
          info->vendor_id = int_value;
          info->has_vendor_id = true;
        }
        if (product_id && base::HexStringToUInt(product_id, &int_value)) {
          info->product_id = int_value;
          info->has_product_id = true;
        }
        if (product_name)
          info->display_name = product_name;
        devices.push_back(std::move(info));
      }
    }
    return devices;
  }
  
  }  // namespace device
  