device/usb/usb_descriptors.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 "device/usb/usb_descriptors.h"
   6
   7 #include <algorithm>
   8
   9 namespace device {
  10
  11 namespace {
  12 const uint8_t kStringDescriptorType = 0x03;
  13 }
  14
  15 UsbEndpointDescriptor::UsbEndpointDescriptor()
  16     : address(0),
  17       direction(USB_DIRECTION_INBOUND),
  18       maximum_packet_size(0),
  19       synchronization_type(USB_SYNCHRONIZATION_NONE),
  20       transfer_type(USB_TRANSFER_CONTROL),
  21       usage_type(USB_USAGE_DATA),
  22       polling_interval(0) {
  23 }
  24
  25 UsbEndpointDescriptor::~UsbEndpointDescriptor() {
  26 }
  27
  28 UsbInterfaceDescriptor::UsbInterfaceDescriptor()
  29     : interface_number(0),
  30       alternate_setting(0),
  31       interface_class(0),
  32       interface_subclass(0),
  33       interface_protocol(0) {
  34 }
  35
  36 UsbInterfaceDescriptor::~UsbInterfaceDescriptor() {
  37 }
  38
  39 UsbConfigDescriptor::UsbConfigDescriptor()
  40     : configuration_value(0),
  41       self_powered(false),
  42       remote_wakeup(false),
  43       maximum_power(0) {
  44 }
  45
  46 UsbConfigDescriptor::~UsbConfigDescriptor() {
  47 }
  48
  49 bool ParseUsbStringDescriptor(const std::vector<uint8_t>& descriptor,
  50                               base::string16* output) {
  51   if (descriptor.size() < 2 || descriptor[1] != kStringDescriptorType) {
  52     return false;
  53   }
  54   // Let the device return a buffer larger than the actual string but prefer the
  55   // length reported inside the descriptor.
  56   size_t length = descriptor[0];
  57   length = std::min(length, descriptor.size());
  58   if (length < 2) {
  59     return false;
  60   } else if (length == 2) {
  61     // Special case to avoid indexing beyond the end of |descriptor|.
  62     *output = base::string16();
  63   } else {
  64     *output = base::string16(
  65         reinterpret_cast<const base::char16*>(&descriptor[2]), length / 2 - 1);
  66   }
  67   return true;
  68 }
  69
  70 }  // namespace device