linux_usbfs.c

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		usbi_err(TRANSFER_CTX(transfer),
			"submiturb failed error %d errno=%d", r, errno);
		return LIBUSB_ERROR_IO;
	}
	return 0;
}

static int op_submit_transfer(struct usbi_transfer *itransfer)
{
	struct libusb_transfer *transfer =
		__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);

	switch (transfer->type) {
	case LIBUSB_TRANSFER_TYPE_CONTROL:
		return submit_control_transfer(itransfer);
	case LIBUSB_TRANSFER_TYPE_BULK:
		return submit_bulk_transfer(itransfer, USBFS_URB_TYPE_BULK);
	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
		return submit_bulk_transfer(itransfer, USBFS_URB_TYPE_INTERRUPT);
	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
		return submit_iso_transfer(itransfer);
	default:
		usbi_err(TRANSFER_CTX(transfer),
			"unknown endpoint type %d", transfer->type);
		return LIBUSB_ERROR_INVALID_PARAM;
	}
}

static int cancel_control_transfer(struct usbi_transfer *itransfer)
{
	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
	struct libusb_transfer *transfer =
		__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct linux_device_handle_priv *dpriv =
		__device_handle_priv(transfer->dev_handle);
	int r;

	tpriv->reap_action = CANCELLED;
	r = ioctl(dpriv->fd, IOCTL_USBFS_DISCARDURB, tpriv->urbs);
	if(r) {
		if (errno == EINVAL) {
			usbi_dbg("URB not found --> assuming ready to be reaped");
			return 0;
		} else {
			usbi_err(TRANSFER_CTX(transfer),
				"unrecognised DISCARD code %d", errno);
			return LIBUSB_ERROR_OTHER;
		}
	}

	return 0;
}

static void cancel_bulk_transfer(struct usbi_transfer *itransfer)
{
	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
	struct libusb_transfer *transfer =
		__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct linux_device_handle_priv *dpriv =
		__device_handle_priv(transfer->dev_handle);
	int i;

	tpriv->reap_action = CANCELLED;
	tpriv->awaiting_reap = 0;
	tpriv->awaiting_discard = 0;
	for (i = 0; i < tpriv->num_urbs; i++) {
		int tmp = ioctl(dpriv->fd, IOCTL_USBFS_DISCARDURB, &tpriv->urbs[i]);
		if (tmp == 0)
			tpriv->awaiting_discard++;
		else if (errno == EINVAL)
			tpriv->awaiting_reap++;
		else
			usbi_warn(TRANSFER_CTX(transfer),
				"unrecognised discard return %d", errno);
	}
}

static void cancel_iso_transfer(struct usbi_transfer *itransfer)
{
	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
	struct libusb_transfer *transfer =
		__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct linux_device_handle_priv *dpriv =
		__device_handle_priv(transfer->dev_handle);
	int i;

	tpriv->reap_action = CANCELLED;
	tpriv->awaiting_reap = 0;
	tpriv->awaiting_discard = 0;
	for (i = 0; i < tpriv->num_urbs; i++) {
		int tmp = ioctl(dpriv->fd, IOCTL_USBFS_DISCARDURB, tpriv->iso_urbs[i]);
		if (tmp == 0)
			tpriv->awaiting_discard++;
		else if (errno == EINVAL)
			tpriv->awaiting_reap++;
		else
			usbi_warn(TRANSFER_CTX(transfer),
				"unrecognised discard return %d", errno);
	}
}

static int op_cancel_transfer(struct usbi_transfer *itransfer)
{
	struct libusb_transfer *transfer =
		__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);

	switch (transfer->type) {
	case LIBUSB_TRANSFER_TYPE_CONTROL:
		return cancel_control_transfer(itransfer);
	case LIBUSB_TRANSFER_TYPE_BULK:
	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
		cancel_bulk_transfer(itransfer);
		return 0;
	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
		cancel_iso_transfer(itransfer);
		return 0;
	default:
		usbi_err(TRANSFER_CTX(transfer),
			"unknown endpoint type %d", transfer->type);
		return LIBUSB_ERROR_INVALID_PARAM;
	}
}

static void op_clear_transfer_priv(struct usbi_transfer *itransfer)
{
	struct libusb_transfer *transfer =
		__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);

	switch (transfer->type) {
	case LIBUSB_TRANSFER_TYPE_CONTROL:
	case LIBUSB_TRANSFER_TYPE_BULK:
	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
		free(tpriv->urbs);
		break;
	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
		free_iso_urbs(tpriv);
		break;
	default:
		usbi_err(TRANSFER_CTX(transfer),
			"unknown endpoint type %d", transfer->type);
	}
}

static int handle_bulk_completion(struct usbi_transfer *itransfer,
	struct usbfs_urb *urb)
{
	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
	int num_urbs = tpriv->num_urbs;
	int urb_idx = urb - tpriv->urbs;
	enum libusb_transfer_status status = LIBUSB_TRANSFER_COMPLETED;

	usbi_dbg("handling completion status %d of bulk urb %d/%d", urb->status,
		urb_idx + 1, num_urbs);

	if (urb->status == 0 ||
			(urb->status == -EOVERFLOW && urb->actual_length > 0))
		itransfer->transferred += urb->actual_length;

	if (tpriv->reap_action != NORMAL) {
		/* cancelled, submit_fail, or completed early */
		if (urb->status == -ENOENT) {
			usbi_dbg("CANCEL: detected a cancelled URB");
			if (tpriv->awaiting_discard == 0)
				usbi_err(ITRANSFER_CTX(itransfer),
					"CANCEL: cancelled URB but not awaiting discards?");
			else
				tpriv->awaiting_discard--;
		} else if (urb->status == 0) {
			usbi_dbg("CANCEL: detected a completed URB");

			/* FIXME we could solve this extreme corner case with a memmove
			 * or something */
			if (tpriv->reap_action == COMPLETED_EARLY)
				usbi_warn(ITRANSFER_CTX(itransfer), "SOME DATA LOST! "
					"(completed early but remaining urb completed)");

			if (tpriv->awaiting_reap == 0)
				usbi_err(ITRANSFER_CTX(itransfer),
					"CANCEL: completed URB not awaiting reap?");
			else
				tpriv->awaiting_reap--;
		} else if (urb->status == -EPIPE || urb->status == -EOVERFLOW) {
			if (tpriv->awaiting_reap == 0)
				usbi_err(ITRANSFER_CTX(itransfer),
					"CANCEL: completed URB not awaiting reap?");
			else
				tpriv->awaiting_reap--;
		} else {
			usbi_warn(ITRANSFER_CTX(itransfer),
				"unhandled CANCEL urb status %d", urb->status);
		}

		if (tpriv->awaiting_reap == 0 && tpriv->awaiting_discard == 0) {
			usbi_dbg("CANCEL: last URB handled, reporting");
			if (tpriv->reap_action == CANCELLED) {
				free(tpriv->urbs);
				usbi_handle_transfer_cancellation(itransfer);
				return 0;
			} else if (tpriv->reap_action == COMPLETED_EARLY) {
				goto out;
			} else {
				status = LIBUSB_TRANSFER_ERROR;
				goto out;
			}
		}
		return 0;
	}

	if (urb->status == -EPIPE) {
		usbi_dbg("detected endpoint stall");
		status = LIBUSB_TRANSFER_STALL;
		goto out;
	} else if (urb->status == -EOVERFLOW) {
		/* overflow can only ever occur in the last urb */
		usbi_dbg("overflow, actual_length=%d", urb->actual_length);
		status = LIBUSB_TRANSFER_OVERFLOW;
		goto out;
	} else if (urb->status != 0) {
		usbi_warn(ITRANSFER_CTX(itransfer),
			"unrecognised urb status %d", urb->status);
	}

	/* if we're the last urb or we got less data than requested then we're
	 * done */
	if (urb_idx == num_urbs - 1) {
		usbi_dbg("last URB in transfer --> complete!");
	} else if (urb->actual_length < urb->buffer_length) {
		struct libusb_transfer *transfer =
			__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
		struct linux_device_handle_priv *dpriv =
			__device_handle_priv(transfer->dev_handle);
		int i;

		usbi_dbg("short transfer %d/%d --> complete!", urb->actual_length,
			urb->buffer_length);

		/* we have to cancel the remaining urbs and wait for their completion
		 * before reporting results */
		tpriv->reap_action = COMPLETED_EARLY;
		for (i = urb_idx + 1; i < tpriv->num_urbs; i++) {
			int r = ioctl(dpriv->fd, IOCTL_USBFS_DISCARDURB, &tpriv->urbs[i]);
			if (r == 0)
				tpriv->awaiting_discard++;
			else if (errno == EINVAL)
				tpriv->awaiting_reap++;
			else
				usbi_warn(ITRANSFER_CTX(itransfer),
					"unrecognised discard return %d", errno);
		}
		return 0;
	} else {
		return 0;
	}

out:
	free(tpriv->urbs);
	usbi_handle_transfer_completion(itransfer, status);
	return 0;
}

static int handle_iso_completion(struct usbi_transfer *itransfer,
	struct usbfs_urb *urb)
{
	struct libusb_transfer *transfer =
		__USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
	int num_urbs = tpriv->num_urbs;
	int urb_idx = 0;
	int i;

	for (i = 0; i < num_urbs; i++) {
		if (urb == tpriv->iso_urbs[i]) {
			urb_idx = i + 1;
			break;
		}
	}
	if (urb_idx == 0) {
		usbi_err(TRANSFER_CTX(transfer), "could not locate urb!");
		return LIBUSB_ERROR_NOT_FOUND;
	}

	usbi_dbg("handling completion status %d of iso urb %d/%d", urb->status,
		urb_idx, num_urbs);

	if (urb->status == 0) {
		/* copy isochronous results back in */

		for (i = 0; i < urb->number_of_packets; i++) {
			struct usbfs_iso_packet_desc *urb_desc = &urb->iso_frame_desc[i];
			struct libusb_iso_packet_descriptor *lib_desc =
				&transfer->iso_packet_desc[tpriv->iso_packet_offset++];
			lib_desc->status = urb_desc->status;
			lib_desc->actual_length = urb_desc->actual_length;
		}
	}

	if (tpriv->reap_action != NORMAL) { /* cancelled or submit_fail */
		if (urb->status == -ENOENT) {
			usbi_dbg("CANCEL: detected a cancelled URB");
			if (tpriv->awaiting_discard == 0)
				usbi_err(TRANSFER_CTX(transfer),
					"CANCEL: cancelled URB but not awaiting discards?");
			else
				tpriv->awaiting_discard--;
		} else if (urb->status == 0) {
			usbi_dbg("CANCEL: detected a completed URB");
			if (tpriv->awaiting_reap == 0)
				usbi_err(TRANSFER_CTX(transfer),
					"CANCEL: completed URB not awaiting reap?");
			else
				tpriv->awaiting_reap--;
		} else {
			usbi_warn(TRANSFER_CTX(transfer),
				"unhandled CANCEL urb status %d", urb->status);
		}

		if (tpriv->awaiting_reap == 0 && tpriv->awaiting_discard == 0) {
			usbi_dbg("CANCEL: last URB handled, reporting");
			free_iso_urbs(tpriv);
			if (tpriv->reap_action == CANCELLED)
				usbi_handle_transfer_cancellation(itransfer);
			else
				usbi_handle_transfer_completion(itransfer,
					LIBUSB_TRANSFER_ERROR);
		}
		return 0;
	}

	if (urb->status != 0)
		usbi_warn(TRANSFER_CTX(transfer),
			"unrecognised urb status %d", urb->status);

	/* if we're the last urb or we got less data than requested then we're
	 * done */
	if (urb_idx == num_urbs) {
		usbi_dbg("last URB in transfer --> complete!");
		free_iso_urbs(tpriv);
		usbi_handle_transfer_completion(itransfer, LIBUSB_TRANSFER_COMPLETED);
	}

	return 0;
}

static int handle_control_completion(struct usbi_transfer *itransfer,
	struct usbfs_urb *urb)
{
	struct linux_transfer_priv *tpriv = usbi_transfer_get_os_priv(itransfer);
	int status;

	usbi_dbg("handling completion status %d", urb->status);

	if (urb->status == 0)
		itransfer->transferred += urb->actual_length;

	if (tpriv->reap_action == CANCELLED) {
		if (urb->status != 0 && urb->status != -ENOENT)
			usbi_warn(ITRANSFER_CTX(itransfer),
				"cancel: unrecognised urb status %d", urb->status);
		free(tpriv->urbs);
		usbi_handle_transfer_cancellation(itransfer);
		return 0;
	}

	if (urb->status == -EPIPE) {
		usbi_dbg("unsupported control request");
		status = LIBUSB_TRANSFER_STALL;
		goto out;
	} else if (urb->status != 0) {
		usbi_warn(ITRANSFER_CTX(itransfer),
			"unrecognised urb status %d", urb->status);
		status = LIBUSB_TRANSFER_ERROR;
		goto out;
	}

	itransfer->transferred = urb->actual_length;
	status = LIBUSB_TRANSFER_COMPLETED;
out:
	free(tpriv->urbs);
	usbi_handle_transfer_completion(itransfer, status);
	return 0;
}

static int reap_for_handle(struct libusb_device_handle *handle)
{
	struct linux_device_handle_priv *hpriv = __device_handle_priv(handle);
	int r;
	struct usbfs_urb *urb;
	struct usbi_transfer *itransfer;
	struct libusb_transfer *transfer;

	r = ioctl(hpriv->fd, IOCTL_USBFS_REAPURBNDELAY, &urb);
	if (r == -1 && errno == EAGAIN)
		return 1;
	if (r < 0) {
		if (errno == ENODEV)
			return LIBUSB_ERROR_NO_DEVICE;

		usbi_err(HANDLE_CTX(handle), "reap failed error %d errno=%d",
			r, errno);
		return LIBUSB_ERROR_IO;
	}

	itransfer = urb->usercontext;
	transfer = __USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);

	usbi_dbg("urb type=%d status=%d transferred=%d", urb->type, urb->status,
		urb->actual_length);

	switch (transfer->type) {
	case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
		return handle_iso_completion(itransfer, urb);
	case LIBUSB_TRANSFER_TYPE_BULK:
	case LIBUSB_TRANSFER_TYPE_INTERRUPT:
		return handle_bulk_completion(itransfer, urb);
	case LIBUSB_TRANSFER_TYPE_CONTROL:
		return handle_control_completion(itransfer, urb);
	default:
		usbi_err(HANDLE_CTX(handle), "unrecognised endpoint type %x",
			transfer->type);
		return LIBUSB_ERROR_OTHER;
	}
}

static int op_handle_events(struct libusb_context *ctx,
	struct pollfd *fds, nfds_t nfds, int num_ready)
{
	int r;
	int i = 0;

	pthread_mutex_lock(&ctx->open_devs_lock);
	for (i = 0; i < nfds && num_ready > 0; i++) {
		struct pollfd *pollfd = &fds[i];
		struct libusb_device_handle *handle;
		struct linux_device_handle_priv *hpriv = NULL;

		if (!pollfd->revents)
			continue;

		num_ready--;
		list_for_each_entry(handle, &ctx->open_devs, list) {
			hpriv =  __device_handle_priv(handle);
			if (hpriv->fd == pollfd->fd)
				break;
		}

		if (pollfd->revents & POLLERR) {
			usbi_remove_pollfd(HANDLE_CTX(handle), hpriv->fd);
			usbi_handle_disconnect(handle);
			continue;
		}

		r = reap_for_handle(handle);
		if (r == 1 || r == LIBUSB_ERROR_NO_DEVICE)
			continue;
		else if (r < 0)
			goto out;
	}

	r = 0;
out:
	pthread_mutex_unlock(&ctx->open_devs_lock);
	return r;
}

const struct usbi_os_backend linux_usbfs_backend = {
	.name = "Linux usbfs",
	.init = op_init,
	.exit = NULL,
	.get_device_list = op_get_device_list,
	.get_device_descriptor = op_get_device_descriptor,
	.get_active_config_descriptor = op_get_active_config_descriptor,
	.get_config_descriptor = op_get_config_descriptor,

	.open = op_open,
	.close = op_close,
	.get_configuration = op_get_configuration,
	.set_configuration = op_set_configuration,
	.claim_interface = op_claim_interface,
	.release_interface = op_release_interface,

	.set_interface_altsetting = op_set_interface,
	.clear_halt = op_clear_halt,
	.reset_device = op_reset_device,

	.kernel_driver_active = op_kernel_driver_active,
	.detach_kernel_driver = op_detach_kernel_driver,

	.destroy_device = op_destroy_device,

	.submit_transfer = op_submit_transfer,
	.cancel_transfer = op_cancel_transfer,
	.clear_transfer_priv = op_clear_transfer_priv,

	.handle_events = op_handle_events,

	.device_priv_size = sizeof(struct linux_device_priv),
	.device_handle_priv_size = sizeof(struct linux_device_handle_priv),
	.transfer_priv_size = sizeof(struct linux_transfer_priv),
	.add_iso_packet_size = 0,
};