components/usb_service/usb_device_handle_impl.cc - platform/external/chromium_org - Git at Google

 // 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 "components/usb_service/usb_device_handle_impl.h"

 #include <algorithm>
 #include <vector>

 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
 #include "base/strings/string16.h"
 #include "base/synchronization/lock.h"
 #include "components/usb_service/usb_context.h"
 #include "components/usb_service/usb_device_impl.h"
 #include "components/usb_service/usb_error.h"
 #include "components/usb_service/usb_interface.h"
 #include "components/usb_service/usb_service.h"
 #include "content/public/browser/browser_thread.h"
 #include "third_party/libusb/src/libusb/libusb.h"

 using content::BrowserThread;

 namespace usb_service {

 typedef libusb_device* PlatformUsbDevice;

 void HandleTransferCompletion(usb_service::PlatformUsbTransferHandle transfer);

 namespace {

 static uint8 ConvertTransferDirection(const UsbEndpointDirection direction) {
   switch (direction) {
     case USB_DIRECTION_INBOUND:
       return LIBUSB_ENDPOINT_IN;
     case USB_DIRECTION_OUTBOUND:
       return LIBUSB_ENDPOINT_OUT;
     default:
       NOTREACHED();
       return LIBUSB_ENDPOINT_IN;
   }
 }

 static uint8 CreateRequestType(
     const UsbEndpointDirection direction,
     const UsbDeviceHandle::TransferRequestType request_type,
     const UsbDeviceHandle::TransferRecipient recipient) {
   uint8 result = ConvertTransferDirection(direction);

   switch (request_type) {
     case UsbDeviceHandle::STANDARD:
       result |= LIBUSB_REQUEST_TYPE_STANDARD;
       break;
     case UsbDeviceHandle::CLASS:
       result |= LIBUSB_REQUEST_TYPE_CLASS;
       break;
     case UsbDeviceHandle::VENDOR:
       result |= LIBUSB_REQUEST_TYPE_VENDOR;
       break;
     case UsbDeviceHandle::RESERVED:
       result |= LIBUSB_REQUEST_TYPE_RESERVED;
       break;
   }

   switch (recipient) {
     case UsbDeviceHandle::DEVICE:
       result |= LIBUSB_RECIPIENT_DEVICE;
       break;
     case UsbDeviceHandle::INTERFACE:
       result |= LIBUSB_RECIPIENT_INTERFACE;
       break;
     case UsbDeviceHandle::ENDPOINT:
       result |= LIBUSB_RECIPIENT_ENDPOINT;
       break;
     case UsbDeviceHandle::OTHER:
       result |= LIBUSB_RECIPIENT_OTHER;
       break;
   }

   return result;
 }

 static UsbTransferStatus ConvertTransferStatus(
     const libusb_transfer_status status) {
   switch (status) {
     case LIBUSB_TRANSFER_COMPLETED:
       return USB_TRANSFER_COMPLETED;
     case LIBUSB_TRANSFER_ERROR:
       return USB_TRANSFER_ERROR;
     case LIBUSB_TRANSFER_TIMED_OUT:
       return USB_TRANSFER_TIMEOUT;
     case LIBUSB_TRANSFER_STALL:
       return USB_TRANSFER_STALLED;
     case LIBUSB_TRANSFER_NO_DEVICE:
       return USB_TRANSFER_DISCONNECT;
     case LIBUSB_TRANSFER_OVERFLOW:
       return USB_TRANSFER_OVERFLOW;
     case LIBUSB_TRANSFER_CANCELLED:
       return USB_TRANSFER_CANCELLED;
     default:
       NOTREACHED();
       return USB_TRANSFER_ERROR;
   }
 }

 static void LIBUSB_CALL
 PlatformTransferCompletionCallback(PlatformUsbTransferHandle transfer) {
   BrowserThread::PostTask(BrowserThread::FILE,
                           FROM_HERE,
                           base::Bind(HandleTransferCompletion, transfer));
 }

 }  // namespace

 void HandleTransferCompletion(PlatformUsbTransferHandle transfer) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   UsbDeviceHandleImpl* const device_handle =
       reinterpret_cast<UsbDeviceHandleImpl*>(transfer->user_data);
   CHECK(device_handle) << "Device handle is closed before transfer finishes.";
   device_handle->TransferComplete(transfer);
   libusb_free_transfer(transfer);
 }

 class UsbDeviceHandleImpl::InterfaceClaimer
     : public base::RefCountedThreadSafe<UsbDeviceHandleImpl::InterfaceClaimer> {
  public:
   InterfaceClaimer(const scoped_refptr<UsbDeviceHandleImpl> handle,
                    const int interface_number);

   bool Claim() const;

   int alternate_setting() const { return alternate_setting_; }
   void set_alternate_setting(const int alternate_setting) {
     alternate_setting_ = alternate_setting;
   }

  private:
   friend class UsbDevice;
   friend class base::RefCountedThreadSafe<InterfaceClaimer>;
   ~InterfaceClaimer();

   const scoped_refptr<UsbDeviceHandleImpl> handle_;
   const int interface_number_;
   int alternate_setting_;

   DISALLOW_COPY_AND_ASSIGN(InterfaceClaimer);
 };

 UsbDeviceHandleImpl::InterfaceClaimer::InterfaceClaimer(
     const scoped_refptr<UsbDeviceHandleImpl> handle,
     const int interface_number)
     : handle_(handle),
       interface_number_(interface_number),
       alternate_setting_(0) {
 }

 UsbDeviceHandleImpl::InterfaceClaimer::~InterfaceClaimer() {
   libusb_release_interface(handle_->handle(), interface_number_);
 }

 bool UsbDeviceHandleImpl::InterfaceClaimer::Claim() const {
   const int rv = libusb_claim_interface(handle_->handle(), interface_number_);
   if (rv != LIBUSB_SUCCESS) {
     LOG(ERROR) << "Failed to claim interface: " << ConvertErrorToString(rv);
   }
   return rv == LIBUSB_SUCCESS;
 }

 struct UsbDeviceHandleImpl::Transfer {
   Transfer();
   ~Transfer();

   UsbTransferType transfer_type;
   scoped_refptr<net::IOBuffer> buffer;
   scoped_refptr<UsbDeviceHandleImpl::InterfaceClaimer> claimed_interface;
   scoped_refptr<base::MessageLoopProxy> message_loop_proxy;
   size_t length;
   UsbTransferCallback callback;
 };

 UsbDeviceHandleImpl::Transfer::Transfer()
     : transfer_type(USB_TRANSFER_CONTROL), length(0) {
 }

 UsbDeviceHandleImpl::Transfer::~Transfer() {
 }

 UsbDeviceHandleImpl::UsbDeviceHandleImpl(
     scoped_refptr<UsbContext> context,
     UsbDeviceImpl* device,
     PlatformUsbDeviceHandle handle,
     scoped_refptr<UsbConfigDescriptor> interfaces)
     : device_(device),
       handle_(handle),
       interfaces_(interfaces),
       context_(context) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(handle) << "Cannot create device with NULL handle.";
   DCHECK(interfaces_) << "Unabled to list interfaces";
 }

 UsbDeviceHandleImpl::~UsbDeviceHandleImpl() {
   DCHECK(thread_checker_.CalledOnValidThread());

   libusb_close(handle_);
   handle_ = NULL;
 }

 scoped_refptr<UsbDevice> UsbDeviceHandleImpl::GetDevice() const {
   return static_cast<UsbDevice*>(device_);
 }

 void UsbDeviceHandleImpl::Close() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (device_)
     device_->Close(this);
 }

 void UsbDeviceHandleImpl::TransferComplete(PlatformUsbTransferHandle handle) {
   DCHECK(ContainsKey(transfers_, handle)) << "Missing transfer completed";

   Transfer transfer = transfers_[handle];
   transfers_.erase(handle);

   DCHECK_GE(handle->actual_length, 0) << "Negative actual length received";
   size_t actual_length =
       static_cast<size_t>(std::max(handle->actual_length, 0));

   DCHECK(transfer.length >= actual_length)
       << "data too big for our buffer (libusb failure?)";

   scoped_refptr<net::IOBuffer> buffer = transfer.buffer;
   switch (transfer.transfer_type) {
     case USB_TRANSFER_CONTROL:
       // If the transfer is a control transfer we do not expose the control
       // setup header to the caller. This logic strips off the header if
       // present before invoking the callback provided with the transfer.
       if (actual_length > 0) {
         CHECK(transfer.length >= LIBUSB_CONTROL_SETUP_SIZE)
             << "buffer was not correctly set: too small for the control header";

         if (transfer.length >= (LIBUSB_CONTROL_SETUP_SIZE + actual_length)) {
           // If the payload is zero bytes long, pad out the allocated buffer
           // size to one byte so that an IOBuffer of that size can be allocated.
           scoped_refptr<net::IOBuffer> resized_buffer =
               new net::IOBuffer(static_cast<int>(
                   std::max(actual_length, static_cast<size_t>(1))));
           memcpy(resized_buffer->data(),
                  buffer->data() + LIBUSB_CONTROL_SETUP_SIZE,
                  actual_length);
           buffer = resized_buffer;
         }
       }
       break;

     case USB_TRANSFER_ISOCHRONOUS:
       // Isochronous replies might carry data in the different isoc packets even
       // if the transfer actual_data value is zero. Furthermore, not all of the
       // received packets might contain data, so we need to calculate how many
       // data bytes we are effectively providing and pack the results.
       if (actual_length == 0) {
         size_t packet_buffer_start = 0;
         for (int i = 0; i < handle->num_iso_packets; ++i) {
           PlatformUsbIsoPacketDescriptor packet = &handle->iso_packet_desc[i];
           if (packet->actual_length > 0) {
             // We don't need to copy as long as all packets until now provide
             // all the data the packet can hold.
             if (actual_length < packet_buffer_start) {
               CHECK(packet_buffer_start + packet->actual_length <=
                     transfer.length);
               memmove(buffer->data() + actual_length,
                       buffer->data() + packet_buffer_start,
                       packet->actual_length);
             }
             actual_length += packet->actual_length;
           }

           packet_buffer_start += packet->length;
         }
       }
       break;

     case USB_TRANSFER_BULK:
     case USB_TRANSFER_INTERRUPT:
       break;

     default:
       NOTREACHED() << "Invalid usb transfer type";
       break;
   }

   transfer.message_loop_proxy->PostTask(
       FROM_HERE,
       base::Bind(transfer.callback,
                  ConvertTransferStatus(handle->status),
                  buffer,
                  actual_length));

   // Must release interface first before actually delete this.
   transfer.claimed_interface = NULL;
 }

 bool UsbDeviceHandleImpl::ClaimInterface(const int interface_number) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!device_)
     return false;
   if (ContainsKey(claimed_interfaces_, interface_number))
     return true;

   scoped_refptr<InterfaceClaimer> claimer =
       new InterfaceClaimer(this, interface_number);

   if (claimer->Claim()) {
     claimed_interfaces_[interface_number] = claimer;
     RefreshEndpointMap();
     return true;
   }
   return false;
 }

 bool UsbDeviceHandleImpl::ReleaseInterface(const int interface_number) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!device_)
     return false;
   if (!ContainsKey(claimed_interfaces_, interface_number))
     return false;

   // Cancel all the transfers on that interface.
   InterfaceClaimer* interface_claimer =
       claimed_interfaces_[interface_number].get();
   for (TransferMap::iterator it = transfers_.begin(); it != transfers_.end();
        ++it) {
     if (it->second.claimed_interface.get() == interface_claimer)
       libusb_cancel_transfer(it->first);
   }
   claimed_interfaces_.erase(interface_number);

   RefreshEndpointMap();
   return true;
 }

 bool UsbDeviceHandleImpl::SetInterfaceAlternateSetting(
     const int interface_number,
     const int alternate_setting) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!device_)
     return false;
   if (!ContainsKey(claimed_interfaces_, interface_number))
     return false;
   const int rv = libusb_set_interface_alt_setting(
       handle_, interface_number, alternate_setting);
   if (rv == LIBUSB_SUCCESS) {
     claimed_interfaces_[interface_number]->set_alternate_setting(
         alternate_setting);
     RefreshEndpointMap();
   } else {
     LOG(ERROR) << "Failed to set interface (" << interface_number
         << ", " << alternate_setting << "): " << ConvertErrorToString(rv);
   }
   return rv == LIBUSB_SUCCESS;
 }

 bool UsbDeviceHandleImpl::ResetDevice() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!device_)
     return false;

   const int rv = libusb_reset_device(handle_);
   if (rv != LIBUSB_SUCCESS) {
     LOG(ERROR) << "Failed to reset device: " << ConvertErrorToString(rv);
   }
   return rv == LIBUSB_SUCCESS;
 }

 bool UsbDeviceHandleImpl::GetSerial(base::string16* serial) {
   DCHECK(thread_checker_.CalledOnValidThread());
   PlatformUsbDevice device = libusb_get_device(handle_);
   libusb_device_descriptor desc;

   const int rv = libusb_get_device_descriptor(device, &desc);
   if (rv != LIBUSB_SUCCESS) {
     LOG(ERROR) << "Failed to read device descriptor: "
         << ConvertErrorToString(rv);
     return false;
   }

   if (desc.iSerialNumber == 0)
     return false;

   // Getting supported language ID.
   uint16 langid[128] = {0};

   int size =
       libusb_get_string_descriptor(handle_,
                                    0,
                                    0,
                                    reinterpret_cast<unsigned char*>(&langid[0]),
                                    sizeof(langid));
   if (size < 0) {
     LOG(ERROR) << "Failed to get language IDs: "
         << ConvertErrorToString(size);
     return false;
   }

   int language_count = (size - 2) / 2;

   for (int i = 1; i <= language_count; ++i) {
     // Get the string using language ID.
     base::char16 text[256] = {0};
     size =
         libusb_get_string_descriptor(handle_,
                                      desc.iSerialNumber,
                                      langid[i],
                                      reinterpret_cast<unsigned char*>(&text[0]),
                                      sizeof(text));
     if (size < 0) {
       LOG(ERROR) << "Failed to get serial number (langid " << langid[i] << "): "
           << ConvertErrorToString(size);
       continue;
     }
     if (size <= 2)
       continue;
     if ((text[0] >> 8) != LIBUSB_DT_STRING)
       continue;
     if ((text[0] & 255) > size)
       continue;

     size = size / 2 - 1;
     *serial = base::string16(text + 1, size);
     return true;
   }
   return false;
 }

 void UsbDeviceHandleImpl::ControlTransfer(
     const UsbEndpointDirection direction,
     const TransferRequestType request_type,
     const TransferRecipient recipient,
     const uint8 request,
     const uint16 value,
     const uint16 index,
     net::IOBuffer* buffer,
     const size_t length,
     const unsigned int timeout,
     const UsbTransferCallback& callback) {
   if (!device_) {
     callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
     return;
   }

   const size_t resized_length = LIBUSB_CONTROL_SETUP_SIZE + length;
   scoped_refptr<net::IOBuffer> resized_buffer(
       new net::IOBufferWithSize(static_cast<int>(resized_length)));
   if (!resized_buffer) {
     callback.Run(USB_TRANSFER_ERROR, buffer, 0);
     return;
   }
   memcpy(resized_buffer->data() + LIBUSB_CONTROL_SETUP_SIZE,
          buffer->data(),
          static_cast<int>(length));

   PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(0);
   const uint8 converted_type =
       CreateRequestType(direction, request_type, recipient);
   libusb_fill_control_setup(reinterpret_cast<uint8*>(resized_buffer->data()),
                             converted_type,
                             request,
                             value,
                             index,
                             static_cast<int16>(length));
   libusb_fill_control_transfer(transfer,
                                handle_,
                                reinterpret_cast<uint8*>(resized_buffer->data()),
                                PlatformTransferCompletionCallback,
                                this,
                                timeout);

   BrowserThread::PostTask(BrowserThread::FILE,
                           FROM_HERE,
                           base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
                                      this,
                                      transfer,
                                      USB_TRANSFER_CONTROL,
                                      resized_buffer,
                                      resized_length,
                                      base::MessageLoopProxy::current(),
                                      callback));
 }

 void UsbDeviceHandleImpl::BulkTransfer(const UsbEndpointDirection direction,
                                        const uint8 endpoint,
                                        net::IOBuffer* buffer,
                                        const size_t length,
                                        const unsigned int timeout,
                                        const UsbTransferCallback& callback) {
   if (!device_) {
     callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
     return;
   }

   PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(0);
   const uint8 new_endpoint = ConvertTransferDirection(direction) | endpoint;
   libusb_fill_bulk_transfer(transfer,
                             handle_,
                             new_endpoint,
                             reinterpret_cast<uint8*>(buffer->data()),
                             static_cast<int>(length),
                             PlatformTransferCompletionCallback,
                             this,
                             timeout);

   BrowserThread::PostTask(BrowserThread::FILE,
                           FROM_HERE,
                           base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
                                      this,
                                      transfer,
                                      USB_TRANSFER_BULK,
                                      make_scoped_refptr(buffer),
                                      length,
                                      base::MessageLoopProxy::current(),
                                      callback));
 }

 void UsbDeviceHandleImpl::InterruptTransfer(
     const UsbEndpointDirection direction,
     const uint8 endpoint,
     net::IOBuffer* buffer,
     const size_t length,
     const unsigned int timeout,
     const UsbTransferCallback& callback) {
   if (!device_) {
     callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
     return;
   }

   PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(0);
   const uint8 new_endpoint = ConvertTransferDirection(direction) | endpoint;
   libusb_fill_interrupt_transfer(transfer,
                                  handle_,
                                  new_endpoint,
                                  reinterpret_cast<uint8*>(buffer->data()),
                                  static_cast<int>(length),
                                  PlatformTransferCompletionCallback,
                                  this,
                                  timeout);
   BrowserThread::PostTask(BrowserThread::FILE,
                           FROM_HERE,
                           base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
                                      this,
                                      transfer,
                                      USB_TRANSFER_INTERRUPT,
                                      make_scoped_refptr(buffer),
                                      length,
                                      base::MessageLoopProxy::current(),
                                      callback));
 }

 void UsbDeviceHandleImpl::IsochronousTransfer(
     const UsbEndpointDirection direction,
     const uint8 endpoint,
     net::IOBuffer* buffer,
     const size_t length,
     const unsigned int packets,
     const unsigned int packet_length,
     const unsigned int timeout,
     const UsbTransferCallback& callback) {
   if (!device_) {
     callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
     return;
   }

   const uint64 total_length = packets * packet_length;
   CHECK(packets <= length && total_length <= length)
       << "transfer length is too small";

   PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(packets);
   const uint8 new_endpoint = ConvertTransferDirection(direction) | endpoint;
   libusb_fill_iso_transfer(transfer,
                            handle_,
                            new_endpoint,
                            reinterpret_cast<uint8*>(buffer->data()),
                            static_cast<int>(length),
                            packets,
                            PlatformTransferCompletionCallback,
                            this,
                            timeout);
   libusb_set_iso_packet_lengths(transfer, packet_length);

   BrowserThread::PostTask(BrowserThread::FILE,
                           FROM_HERE,
                           base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
                                      this,
                                      transfer,
                                      USB_TRANSFER_ISOCHRONOUS,
                                      make_scoped_refptr(buffer),
                                      length,
                                      base::MessageLoopProxy::current(),
                                      callback));
 }

 void UsbDeviceHandleImpl::RefreshEndpointMap() {
   DCHECK(thread_checker_.CalledOnValidThread());
   endpoint_map_.clear();
   for (ClaimedInterfaceMap::iterator it = claimed_interfaces_.begin();
        it != claimed_interfaces_.end();
        ++it) {
     scoped_refptr<const UsbInterfaceAltSettingDescriptor> interface_desc =
         interfaces_->GetInterface(it->first)
             ->GetAltSetting(it->second->alternate_setting());
     for (size_t i = 0; i < interface_desc->GetNumEndpoints(); i++) {
       scoped_refptr<const UsbEndpointDescriptor> endpoint =
           interface_desc->GetEndpoint(i);
       endpoint_map_[endpoint->GetAddress()] = it->first;
     }
   }
 }

 scoped_refptr<UsbDeviceHandleImpl::InterfaceClaimer>
 UsbDeviceHandleImpl::GetClaimedInterfaceForEndpoint(unsigned char endpoint) {
   unsigned char address = endpoint & LIBUSB_ENDPOINT_ADDRESS_MASK;
   if (ContainsKey(endpoint_map_, address))
     return claimed_interfaces_[endpoint_map_[address]];
   return NULL;
 }

 void UsbDeviceHandleImpl::SubmitTransfer(
     PlatformUsbTransferHandle handle,
     UsbTransferType transfer_type,
     net::IOBuffer* buffer,
     const size_t length,
     scoped_refptr<base::MessageLoopProxy> message_loop_proxy,
     const UsbTransferCallback& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!device_) {
     message_loop_proxy->PostTask(
         FROM_HERE,
         base::Bind(
             callback, USB_TRANSFER_DISCONNECT, make_scoped_refptr(buffer), 0));
   }

   Transfer transfer;
   transfer.transfer_type = transfer_type;
   transfer.buffer = buffer;
   transfer.length = length;
   transfer.callback = callback;
   transfer.message_loop_proxy = message_loop_proxy;

   // It's OK for this method to return NULL. libusb_submit_transfer will fail if
   // it requires an interface we didn't claim.
   transfer.claimed_interface = GetClaimedInterfaceForEndpoint(handle->endpoint);

   const int rv = libusb_submit_transfer(handle);
   if (rv == LIBUSB_SUCCESS) {
     transfers_[handle] = transfer;
   } else {
     LOG(ERROR) << "Failed to submit transfer: " << ConvertErrorToString(rv);
     message_loop_proxy->PostTask(
         FROM_HERE,
         base::Bind(
             callback, USB_TRANSFER_ERROR, make_scoped_refptr(buffer), 0));
   }
 }

 void UsbDeviceHandleImpl::InternalClose() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!device_)
     return;

   // Cancel all the transfers.
   for (TransferMap::iterator it = transfers_.begin(); it != transfers_.end();
        ++it) {
     // The callback will be called some time later.
     libusb_cancel_transfer(it->first);
   }

   // Attempt-release all the interfaces.
   // It will be retained until the transfer cancellation is finished.
   claimed_interfaces_.clear();

   // Cannot close device handle here. Need to wait for libusb_cancel_transfer to
   // finish.
   device_ = NULL;
 }

 }  // namespace usb_service
	// 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 "components/usb_service/usb_device_handle_impl.h"

	#include <algorithm>
	#include <vector>

	#include "base/message_loop/message_loop.h"
	#include "base/stl_util.h"
	#include "base/strings/string16.h"
	#include "base/synchronization/lock.h"
	#include "components/usb_service/usb_context.h"
	#include "components/usb_service/usb_device_impl.h"
	#include "components/usb_service/usb_error.h"
	#include "components/usb_service/usb_interface.h"
	#include "components/usb_service/usb_service.h"
	#include "content/public/browser/browser_thread.h"
	#include "third_party/libusb/src/libusb/libusb.h"

	using content::BrowserThread;

	namespace usb_service {

	typedef libusb_device* PlatformUsbDevice;

	void HandleTransferCompletion(usb_service::PlatformUsbTransferHandle transfer);

	namespace {

	static uint8 ConvertTransferDirection(const UsbEndpointDirection direction) {
	switch (direction) {
	case USB_DIRECTION_INBOUND:
	return LIBUSB_ENDPOINT_IN;
	case USB_DIRECTION_OUTBOUND:
	return LIBUSB_ENDPOINT_OUT;
	default:
	NOTREACHED();
	return LIBUSB_ENDPOINT_IN;
	}
	}

	static uint8 CreateRequestType(
	const UsbEndpointDirection direction,
	const UsbDeviceHandle::TransferRequestType request_type,
	const UsbDeviceHandle::TransferRecipient recipient) {
	uint8 result = ConvertTransferDirection(direction);

	switch (request_type) {
	case UsbDeviceHandle::STANDARD:
	result \|= LIBUSB_REQUEST_TYPE_STANDARD;
	break;
	case UsbDeviceHandle::CLASS:
	result \|= LIBUSB_REQUEST_TYPE_CLASS;
	break;
	case UsbDeviceHandle::VENDOR:
	result \|= LIBUSB_REQUEST_TYPE_VENDOR;
	break;
	case UsbDeviceHandle::RESERVED:
	result \|= LIBUSB_REQUEST_TYPE_RESERVED;
	break;
	}

	switch (recipient) {
	case UsbDeviceHandle::DEVICE:
	result \|= LIBUSB_RECIPIENT_DEVICE;
	break;
	case UsbDeviceHandle::INTERFACE:
	result \|= LIBUSB_RECIPIENT_INTERFACE;
	break;
	case UsbDeviceHandle::ENDPOINT:
	result \|= LIBUSB_RECIPIENT_ENDPOINT;
	break;
	case UsbDeviceHandle::OTHER:
	result \|= LIBUSB_RECIPIENT_OTHER;
	break;
	}

	return result;
	}

	static UsbTransferStatus ConvertTransferStatus(
	const libusb_transfer_status status) {
	switch (status) {
	case LIBUSB_TRANSFER_COMPLETED:
	return USB_TRANSFER_COMPLETED;
	case LIBUSB_TRANSFER_ERROR:
	return USB_TRANSFER_ERROR;
	case LIBUSB_TRANSFER_TIMED_OUT:
	return USB_TRANSFER_TIMEOUT;
	case LIBUSB_TRANSFER_STALL:
	return USB_TRANSFER_STALLED;
	case LIBUSB_TRANSFER_NO_DEVICE:
	return USB_TRANSFER_DISCONNECT;
	case LIBUSB_TRANSFER_OVERFLOW:
	return USB_TRANSFER_OVERFLOW;
	case LIBUSB_TRANSFER_CANCELLED:
	return USB_TRANSFER_CANCELLED;
	default:
	NOTREACHED();
	return USB_TRANSFER_ERROR;
	}
	}

	static void LIBUSB_CALL
	PlatformTransferCompletionCallback(PlatformUsbTransferHandle transfer) {
	BrowserThread::PostTask(BrowserThread::FILE,
	FROM_HERE,
	base::Bind(HandleTransferCompletion, transfer));
	}

	} // namespace

	void HandleTransferCompletion(PlatformUsbTransferHandle transfer) {
	DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
	UsbDeviceHandleImpl* const device_handle =
	reinterpret_cast<UsbDeviceHandleImpl*>(transfer->user_data);
	CHECK(device_handle) << "Device handle is closed before transfer finishes.";
	device_handle->TransferComplete(transfer);
	libusb_free_transfer(transfer);
	}

	class UsbDeviceHandleImpl::InterfaceClaimer
	: public base::RefCountedThreadSafe<UsbDeviceHandleImpl::InterfaceClaimer> {
	public:
	InterfaceClaimer(const scoped_refptr<UsbDeviceHandleImpl> handle,
	const int interface_number);

	bool Claim() const;

	int alternate_setting() const { return alternate_setting_; }
	void set_alternate_setting(const int alternate_setting) {
	alternate_setting_ = alternate_setting;
	}

	private:
	friend class UsbDevice;
	friend class base::RefCountedThreadSafe<InterfaceClaimer>;
	~InterfaceClaimer();

	const scoped_refptr<UsbDeviceHandleImpl> handle_;
	const int interface_number_;
	int alternate_setting_;

	DISALLOW_COPY_AND_ASSIGN(InterfaceClaimer);
	};

	UsbDeviceHandleImpl::InterfaceClaimer::InterfaceClaimer(
	const scoped_refptr<UsbDeviceHandleImpl> handle,
	const int interface_number)
	: handle_(handle),
	interface_number_(interface_number),
	alternate_setting_(0) {
	}

	UsbDeviceHandleImpl::InterfaceClaimer::~InterfaceClaimer() {
	libusb_release_interface(handle_->handle(), interface_number_);
	}

	bool UsbDeviceHandleImpl::InterfaceClaimer::Claim() const {
	const int rv = libusb_claim_interface(handle_->handle(), interface_number_);
	if (rv != LIBUSB_SUCCESS) {
	LOG(ERROR) << "Failed to claim interface: " << ConvertErrorToString(rv);
	}
	return rv == LIBUSB_SUCCESS;
	}

	struct UsbDeviceHandleImpl::Transfer {
	Transfer();
	~Transfer();

	UsbTransferType transfer_type;
	scoped_refptr<net::IOBuffer> buffer;
	scoped_refptr<UsbDeviceHandleImpl::InterfaceClaimer> claimed_interface;
	scoped_refptr<base::MessageLoopProxy> message_loop_proxy;
	size_t length;
	UsbTransferCallback callback;
	};

	UsbDeviceHandleImpl::Transfer::Transfer()
	: transfer_type(USB_TRANSFER_CONTROL), length(0) {
	}

	UsbDeviceHandleImpl::Transfer::~Transfer() {
	}

	UsbDeviceHandleImpl::UsbDeviceHandleImpl(
	scoped_refptr<UsbContext> context,
	UsbDeviceImpl* device,
	PlatformUsbDeviceHandle handle,
	scoped_refptr<UsbConfigDescriptor> interfaces)
	: device_(device),
	handle_(handle),
	interfaces_(interfaces),
	context_(context) {
	DCHECK(thread_checker_.CalledOnValidThread());
	DCHECK(handle) << "Cannot create device with NULL handle.";
	DCHECK(interfaces_) << "Unabled to list interfaces";
	}

	UsbDeviceHandleImpl::~UsbDeviceHandleImpl() {
	DCHECK(thread_checker_.CalledOnValidThread());

	libusb_close(handle_);
	handle_ = NULL;
	}

	scoped_refptr<UsbDevice> UsbDeviceHandleImpl::GetDevice() const {
	return static_cast<UsbDevice*>(device_);
	}

	void UsbDeviceHandleImpl::Close() {
	DCHECK(thread_checker_.CalledOnValidThread());
	if (device_)
	device_->Close(this);
	}

	void UsbDeviceHandleImpl::TransferComplete(PlatformUsbTransferHandle handle) {
	DCHECK(ContainsKey(transfers_, handle)) << "Missing transfer completed";

	Transfer transfer = transfers_[handle];
	transfers_.erase(handle);

	DCHECK_GE(handle->actual_length, 0) << "Negative actual length received";
	size_t actual_length =
	static_cast<size_t>(std::max(handle->actual_length, 0));

	DCHECK(transfer.length >= actual_length)
	<< "data too big for our buffer (libusb failure?)";

	scoped_refptr<net::IOBuffer> buffer = transfer.buffer;
	switch (transfer.transfer_type) {
	case USB_TRANSFER_CONTROL:
	// If the transfer is a control transfer we do not expose the control
	// setup header to the caller. This logic strips off the header if
	// present before invoking the callback provided with the transfer.
	if (actual_length > 0) {
	CHECK(transfer.length >= LIBUSB_CONTROL_SETUP_SIZE)
	<< "buffer was not correctly set: too small for the control header";

	if (transfer.length >= (LIBUSB_CONTROL_SETUP_SIZE + actual_length)) {
	// If the payload is zero bytes long, pad out the allocated buffer
	// size to one byte so that an IOBuffer of that size can be allocated.
	scoped_refptr<net::IOBuffer> resized_buffer =
	new net::IOBuffer(static_cast<int>(
	std::max(actual_length, static_cast<size_t>(1))));
	memcpy(resized_buffer->data(),
	buffer->data() + LIBUSB_CONTROL_SETUP_SIZE,
	actual_length);
	buffer = resized_buffer;
	}
	}
	break;

	case USB_TRANSFER_ISOCHRONOUS:
	// Isochronous replies might carry data in the different isoc packets even
	// if the transfer actual_data value is zero. Furthermore, not all of the
	// received packets might contain data, so we need to calculate how many
	// data bytes we are effectively providing and pack the results.
	if (actual_length == 0) {
	size_t packet_buffer_start = 0;
	for (int i = 0; i < handle->num_iso_packets; ++i) {
	PlatformUsbIsoPacketDescriptor packet = &handle->iso_packet_desc[i];
	if (packet->actual_length > 0) {
	// We don't need to copy as long as all packets until now provide
	// all the data the packet can hold.
	if (actual_length < packet_buffer_start) {
	CHECK(packet_buffer_start + packet->actual_length <=
	transfer.length);
	memmove(buffer->data() + actual_length,
	buffer->data() + packet_buffer_start,
	packet->actual_length);
	}
	actual_length += packet->actual_length;
	}

	packet_buffer_start += packet->length;
	}
	}
	break;

	case USB_TRANSFER_BULK:
	case USB_TRANSFER_INTERRUPT:
	break;

	default:
	NOTREACHED() << "Invalid usb transfer type";
	break;
	}

	transfer.message_loop_proxy->PostTask(
	FROM_HERE,
	base::Bind(transfer.callback,
	ConvertTransferStatus(handle->status),
	buffer,
	actual_length));

	// Must release interface first before actually delete this.
	transfer.claimed_interface = NULL;
	}

	bool UsbDeviceHandleImpl::ClaimInterface(const int interface_number) {
	DCHECK(thread_checker_.CalledOnValidThread());
	if (!device_)
	return false;
	if (ContainsKey(claimed_interfaces_, interface_number))
	return true;

	scoped_refptr<InterfaceClaimer> claimer =
	new InterfaceClaimer(this, interface_number);

	if (claimer->Claim()) {
	claimed_interfaces_[interface_number] = claimer;
	RefreshEndpointMap();
	return true;
	}
	return false;
	}

	bool UsbDeviceHandleImpl::ReleaseInterface(const int interface_number) {
	DCHECK(thread_checker_.CalledOnValidThread());
	if (!device_)
	return false;
	if (!ContainsKey(claimed_interfaces_, interface_number))
	return false;

	// Cancel all the transfers on that interface.
	InterfaceClaimer* interface_claimer =
	claimed_interfaces_[interface_number].get();
	for (TransferMap::iterator it = transfers_.begin(); it != transfers_.end();
	++it) {
	if (it->second.claimed_interface.get() == interface_claimer)
	libusb_cancel_transfer(it->first);
	}
	claimed_interfaces_.erase(interface_number);

	RefreshEndpointMap();
	return true;
	}

	bool UsbDeviceHandleImpl::SetInterfaceAlternateSetting(
	const int interface_number,
	const int alternate_setting) {
	DCHECK(thread_checker_.CalledOnValidThread());
	if (!device_)
	return false;
	if (!ContainsKey(claimed_interfaces_, interface_number))
	return false;
	const int rv = libusb_set_interface_alt_setting(
	handle_, interface_number, alternate_setting);
	if (rv == LIBUSB_SUCCESS) {
	claimed_interfaces_[interface_number]->set_alternate_setting(
	alternate_setting);
	RefreshEndpointMap();
	} else {
	LOG(ERROR) << "Failed to set interface (" << interface_number
	<< ", " << alternate_setting << "): " << ConvertErrorToString(rv);
	}
	return rv == LIBUSB_SUCCESS;
	}

	bool UsbDeviceHandleImpl::ResetDevice() {
	DCHECK(thread_checker_.CalledOnValidThread());
	if (!device_)
	return false;

	const int rv = libusb_reset_device(handle_);
	if (rv != LIBUSB_SUCCESS) {
	LOG(ERROR) << "Failed to reset device: " << ConvertErrorToString(rv);
	}
	return rv == LIBUSB_SUCCESS;
	}

	bool UsbDeviceHandleImpl::GetSerial(base::string16* serial) {
	DCHECK(thread_checker_.CalledOnValidThread());
	PlatformUsbDevice device = libusb_get_device(handle_);
	libusb_device_descriptor desc;

	const int rv = libusb_get_device_descriptor(device, &desc);
	if (rv != LIBUSB_SUCCESS) {
	LOG(ERROR) << "Failed to read device descriptor: "
	<< ConvertErrorToString(rv);
	return false;
	}

	if (desc.iSerialNumber == 0)
	return false;

	// Getting supported language ID.
	uint16 langid[128] = {0};

	int size =
	libusb_get_string_descriptor(handle_,
	0,
	0,
	reinterpret_cast<unsigned char*>(&langid[0]),
	sizeof(langid));
	if (size < 0) {
	LOG(ERROR) << "Failed to get language IDs: "
	<< ConvertErrorToString(size);
	return false;
	}

	int language_count = (size - 2) / 2;

	for (int i = 1; i <= language_count; ++i) {
	// Get the string using language ID.
	base::char16 text[256] = {0};
	size =
	libusb_get_string_descriptor(handle_,
	desc.iSerialNumber,
	langid[i],
	reinterpret_cast<unsigned char*>(&text[0]),
	sizeof(text));
	if (size < 0) {
	LOG(ERROR) << "Failed to get serial number (langid " << langid[i] << "): "
	<< ConvertErrorToString(size);
	continue;
	}
	if (size <= 2)
	continue;
	if ((text[0] >> 8) != LIBUSB_DT_STRING)
	continue;
	if ((text[0] & 255) > size)
	continue;

	size = size / 2 - 1;
	*serial = base::string16(text + 1, size);
	return true;
	}
	return false;
	}

	void UsbDeviceHandleImpl::ControlTransfer(
	const UsbEndpointDirection direction,
	const TransferRequestType request_type,
	const TransferRecipient recipient,
	const uint8 request,
	const uint16 value,
	const uint16 index,
	net::IOBuffer* buffer,
	const size_t length,
	const unsigned int timeout,
	const UsbTransferCallback& callback) {
	if (!device_) {
	callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
	return;
	}

	const size_t resized_length = LIBUSB_CONTROL_SETUP_SIZE + length;
	scoped_refptr<net::IOBuffer> resized_buffer(
	new net::IOBufferWithSize(static_cast<int>(resized_length)));
	if (!resized_buffer) {
	callback.Run(USB_TRANSFER_ERROR, buffer, 0);
	return;
	}
	memcpy(resized_buffer->data() + LIBUSB_CONTROL_SETUP_SIZE,
	buffer->data(),
	static_cast<int>(length));

	PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(0);
	const uint8 converted_type =
	CreateRequestType(direction, request_type, recipient);
	libusb_fill_control_setup(reinterpret_cast<uint8*>(resized_buffer->data()),
	converted_type,
	request,
	value,
	index,
	static_cast<int16>(length));
	libusb_fill_control_transfer(transfer,
	handle_,
	reinterpret_cast<uint8*>(resized_buffer->data()),
	PlatformTransferCompletionCallback,
	this,
	timeout);

	BrowserThread::PostTask(BrowserThread::FILE,
	FROM_HERE,
	base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
	this,
	transfer,
	USB_TRANSFER_CONTROL,
	resized_buffer,
	resized_length,
	base::MessageLoopProxy::current(),
	callback));
	}

	void UsbDeviceHandleImpl::BulkTransfer(const UsbEndpointDirection direction,
	const uint8 endpoint,
	net::IOBuffer* buffer,
	const size_t length,
	const unsigned int timeout,
	const UsbTransferCallback& callback) {
	if (!device_) {
	callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
	return;
	}

	PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(0);
	const uint8 new_endpoint = ConvertTransferDirection(direction) \| endpoint;
	libusb_fill_bulk_transfer(transfer,
	handle_,
	new_endpoint,
	reinterpret_cast<uint8*>(buffer->data()),
	static_cast<int>(length),
	PlatformTransferCompletionCallback,
	this,
	timeout);

	BrowserThread::PostTask(BrowserThread::FILE,
	FROM_HERE,
	base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
	this,
	transfer,
	USB_TRANSFER_BULK,
	make_scoped_refptr(buffer),
	length,
	base::MessageLoopProxy::current(),
	callback));
	}

	void UsbDeviceHandleImpl::InterruptTransfer(
	const UsbEndpointDirection direction,
	const uint8 endpoint,
	net::IOBuffer* buffer,
	const size_t length,
	const unsigned int timeout,
	const UsbTransferCallback& callback) {
	if (!device_) {
	callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
	return;
	}

	PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(0);
	const uint8 new_endpoint = ConvertTransferDirection(direction) \| endpoint;
	libusb_fill_interrupt_transfer(transfer,
	handle_,
	new_endpoint,
	reinterpret_cast<uint8*>(buffer->data()),
	static_cast<int>(length),
	PlatformTransferCompletionCallback,
	this,
	timeout);
	BrowserThread::PostTask(BrowserThread::FILE,
	FROM_HERE,
	base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
	this,
	transfer,
	USB_TRANSFER_INTERRUPT,
	make_scoped_refptr(buffer),
	length,
	base::MessageLoopProxy::current(),
	callback));
	}

	void UsbDeviceHandleImpl::IsochronousTransfer(
	const UsbEndpointDirection direction,
	const uint8 endpoint,
	net::IOBuffer* buffer,
	const size_t length,
	const unsigned int packets,
	const unsigned int packet_length,
	const unsigned int timeout,
	const UsbTransferCallback& callback) {
	if (!device_) {
	callback.Run(USB_TRANSFER_DISCONNECT, buffer, 0);
	return;
	}

	const uint64 total_length = packets * packet_length;
	CHECK(packets <= length && total_length <= length)
	<< "transfer length is too small";

	PlatformUsbTransferHandle const transfer = libusb_alloc_transfer(packets);
	const uint8 new_endpoint = ConvertTransferDirection(direction) \| endpoint;
	libusb_fill_iso_transfer(transfer,
	handle_,
	new_endpoint,
	reinterpret_cast<uint8*>(buffer->data()),
	static_cast<int>(length),
	packets,
	PlatformTransferCompletionCallback,
	this,
	timeout);
	libusb_set_iso_packet_lengths(transfer, packet_length);

	BrowserThread::PostTask(BrowserThread::FILE,
	FROM_HERE,
	base::Bind(&UsbDeviceHandleImpl::SubmitTransfer,
	this,
	transfer,
	USB_TRANSFER_ISOCHRONOUS,
	make_scoped_refptr(buffer),
	length,
	base::MessageLoopProxy::current(),
	callback));
	}

	void UsbDeviceHandleImpl::RefreshEndpointMap() {
	DCHECK(thread_checker_.CalledOnValidThread());
	endpoint_map_.clear();
	for (ClaimedInterfaceMap::iterator it = claimed_interfaces_.begin();
	it != claimed_interfaces_.end();
	++it) {
	scoped_refptr<const UsbInterfaceAltSettingDescriptor> interface_desc =
	interfaces_->GetInterface(it->first)
	->GetAltSetting(it->second->alternate_setting());
	for (size_t i = 0; i < interface_desc->GetNumEndpoints(); i++) {
	scoped_refptr<const UsbEndpointDescriptor> endpoint =
	interface_desc->GetEndpoint(i);
	endpoint_map_[endpoint->GetAddress()] = it->first;
	}
	}
	}

	scoped_refptr<UsbDeviceHandleImpl::InterfaceClaimer>
	UsbDeviceHandleImpl::GetClaimedInterfaceForEndpoint(unsigned char endpoint) {
	unsigned char address = endpoint & LIBUSB_ENDPOINT_ADDRESS_MASK;
	if (ContainsKey(endpoint_map_, address))
	return claimed_interfaces_[endpoint_map_[address]];
	return NULL;
	}

	void UsbDeviceHandleImpl::SubmitTransfer(
	PlatformUsbTransferHandle handle,
	UsbTransferType transfer_type,
	net::IOBuffer* buffer,
	const size_t length,
	scoped_refptr<base::MessageLoopProxy> message_loop_proxy,
	const UsbTransferCallback& callback) {
	DCHECK(thread_checker_.CalledOnValidThread());
	if (!device_) {
	message_loop_proxy->PostTask(
	FROM_HERE,
	base::Bind(
	callback, USB_TRANSFER_DISCONNECT, make_scoped_refptr(buffer), 0));
	}

	Transfer transfer;
	transfer.transfer_type = transfer_type;
	transfer.buffer = buffer;
	transfer.length = length;
	transfer.callback = callback;
	transfer.message_loop_proxy = message_loop_proxy;

	// It's OK for this method to return NULL. libusb_submit_transfer will fail if
	// it requires an interface we didn't claim.
	transfer.claimed_interface = GetClaimedInterfaceForEndpoint(handle->endpoint);

	const int rv = libusb_submit_transfer(handle);
	if (rv == LIBUSB_SUCCESS) {
	transfers_[handle] = transfer;
	} else {
	LOG(ERROR) << "Failed to submit transfer: " << ConvertErrorToString(rv);
	message_loop_proxy->PostTask(
	FROM_HERE,
	base::Bind(
	callback, USB_TRANSFER_ERROR, make_scoped_refptr(buffer), 0));
	}
	}

	void UsbDeviceHandleImpl::InternalClose() {
	DCHECK(thread_checker_.CalledOnValidThread());
	if (!device_)
	return;

	// Cancel all the transfers.
	for (TransferMap::iterator it = transfers_.begin(); it != transfers_.end();
	++it) {
	// The callback will be called some time later.
	libusb_cancel_transfer(it->first);
	}

	// Attempt-release all the interfaces.
	// It will be retained until the transfer cancellation is finished.
	claimed_interfaces_.clear();

	// Cannot close device handle here. Need to wait for libusb_cancel_transfer to
	// finish.
	device_ = NULL;
	}

	} // namespace usb_service