core.c

最新的libusb库

		return NULL;

	r = pthread_mutex_init(&dev->lock, NULL);
	if (r)
		return NULL;

	dev->ctx = ctx;
	dev->refcnt = 1;
	dev->session_data = session_id;
	memset(&dev->os_priv, 0, priv_size);

	pthread_mutex_lock(&ctx->usb_devs_lock);
	list_add(&dev->list, &ctx->usb_devs);
	pthread_mutex_unlock(&ctx->usb_devs_lock);
	return dev;
}

/* Perform some final sanity checks on a newly discovered device. If this
 * function fails (negative return code), the device should not be added
 * to the discovered device list. */
int usbi_sanitize_device(struct libusb_device *dev)
{
	int r;
	unsigned char raw_desc[DEVICE_DESC_LENGTH];
	uint8_t num_configurations;
	int host_endian;

	r = usbi_backend->get_device_descriptor(dev, raw_desc, &host_endian);
	if (r < 0)
		return r;

	num_configurations = raw_desc[DEVICE_DESC_LENGTH - 1];
	if (num_configurations > USB_MAXCONFIG) {
		usbi_err(DEVICE_CTX(dev), "too many configurations");
		return LIBUSB_ERROR_IO;
	} else if (num_configurations < 1) {
		usbi_dbg("no configurations?");
		return LIBUSB_ERROR_IO;
	}

	dev->num_configurations = num_configurations;
	return 0;
}

/* Examine libusb's internal list of known devices, looking for one with
 * a specific session ID. Returns the matching device if it was found, and
 * NULL otherwise. */
struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
	unsigned long session_id)
{
	struct libusb_device *dev;
	struct libusb_device *ret = NULL;

	pthread_mutex_lock(&ctx->usb_devs_lock);
	list_for_each_entry(dev, &ctx->usb_devs, list)
		if (dev->session_data == session_id) {
			ret = dev;
			break;
		}
	pthread_mutex_unlock(&ctx->usb_devs_lock);

	return ret;
}

/** @ingroup dev
 * Returns a list of USB devices currently attached to the system. This is
 * your entry point into finding a USB device to operate.
 *
 * You are expected to unreference all the devices when you are done with
 * them, and then free the list with libusb_free_device_list(). Note that
 * libusb_free_device_list() can unref all the devices for you. Be careful
 * not to unreference a device you are about to open until after you have
 * opened it.
 *
 * This return value of this function indicates the number of devices in
 * the resultant list. The list is actually one element larger, as it is
 * NULL-terminated.
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param list output location for a list of devices. Must be later freed with
 * libusb_free_device_list().
 * \returns the number of devices in the outputted list, or LIBUSB_ERROR_NO_MEM
 * on memory allocation failure.
 */
API_EXPORTED ssize_t libusb_get_device_list(libusb_context *ctx,
	libusb_device ***list)
{
	struct discovered_devs *discdevs = discovered_devs_alloc();
	struct libusb_device **ret;
	int r = 0;
	size_t i;
	ssize_t len;
	USBI_GET_CONTEXT(ctx);
	usbi_dbg("");

	if (!discdevs)
		return LIBUSB_ERROR_NO_MEM;

	r = usbi_backend->get_device_list(ctx, &discdevs);
	if (r < 0) {
		len = r;
		goto out;
	}

	/* convert discovered_devs into a list */
	len = discdevs->len;
	ret = malloc(sizeof(void *) * (len + 1));
	if (!ret) {
		len = LIBUSB_ERROR_NO_MEM;
		goto out;
	}

	ret[len] = NULL;
	for (i = 0; i < len; i++) {
		struct libusb_device *dev = discdevs->devices[i];
		ret[i] = libusb_ref_device(dev);
	}
	*list = ret;

out:
	discovered_devs_free(discdevs);
	return len;
}

/** \ingroup dev
 * Frees a list of devices previously discovered using
 * libusb_get_device_list(). If the unref_devices parameter is set, the
 * reference count of each device in the list is decremented by 1.
 * \param list the list to free
 * \param unref_devices whether to unref the devices in the list
 */
API_EXPORTED void libusb_free_device_list(libusb_device **list,
	int unref_devices)
{
	if (!list)
		return;

	if (unref_devices) {
		int i = 0;
		struct libusb_device *dev;

		while ((dev = list[i++]) != NULL)
			libusb_unref_device(dev);
	}
	free(list);
}

/** \ingroup dev
 * Get the number of the bus that a device is connected to.
 * \param dev a device
 * \returns the bus number
 */
API_EXPORTED uint8_t libusb_get_bus_number(libusb_device *dev)
{
	return dev->bus_number;
}

/** \ingroup dev
 * Get the address of the device on the bus it is connected to.
 * \param dev a device
 * \returns the device address
 */
API_EXPORTED uint8_t libusb_get_device_address(libusb_device *dev)
{
	return dev->device_address;
}

/** \ingroup dev
 * Convenience function to retrieve the wMaxPacketSize value for a particular
 * endpoint in the active device configuration. This is useful for setting up
 * isochronous transfers.
 *
 * \param dev a device
 * \param endpoint address of the endpoint in question
 * \returns the wMaxPacketSize value
 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
 * \returns LIBUSB_ERROR_OTHER on other failure
 */
API_EXPORTED int libusb_get_max_packet_size(libusb_device *dev,
	unsigned char endpoint)
{
	int iface_idx;
	struct libusb_config_descriptor *config;
	int r;
	
	r = libusb_get_active_config_descriptor(dev, &config);
	if (r < 0) {
		usbi_err(DEVICE_CTX(dev),
			"could not retrieve active config descriptor");
		return LIBUSB_ERROR_OTHER;
	}

	r = LIBUSB_ERROR_NOT_FOUND;
	for (iface_idx = 0; iface_idx < config->bNumInterfaces; iface_idx++) {
		const struct libusb_interface *iface = &config->interface[iface_idx];
		int altsetting_idx;

		for (altsetting_idx = 0; altsetting_idx < iface->num_altsetting;
				altsetting_idx++) {
			const struct libusb_interface_descriptor *altsetting
				= &iface->altsetting[altsetting_idx];
			int ep_idx;

			for (ep_idx = 0; ep_idx < altsetting->bNumEndpoints; ep_idx++) {
				const struct libusb_endpoint_descriptor *ep =
					&altsetting->endpoint[ep_idx];
				if (ep->bEndpointAddress == endpoint) {
					r = ep->wMaxPacketSize;
					goto out;
				}
			}
		}
	}

out:
	libusb_free_config_descriptor(config);
	return r;
}

/** \ingroup dev
 * Increment the reference count of a device.
 * \param dev the device to reference
 * \returns the same device
 */
API_EXPORTED libusb_device *libusb_ref_device(libusb_device *dev)
{
	pthread_mutex_lock(&dev->lock);
	dev->refcnt++;
	pthread_mutex_unlock(&dev->lock);
	return dev;
}

/** \ingroup dev
 * Decrement the reference count of a device. If the decrement operation
 * causes the reference count to reach zero, the device shall be destroyed.
 * \param dev the device to unreference
 */
API_EXPORTED void libusb_unref_device(libusb_device *dev)
{
	int refcnt;

	if (!dev)
		return;

	pthread_mutex_lock(&dev->lock);
	refcnt = --dev->refcnt;
	pthread_mutex_unlock(&dev->lock);

	if (refcnt == 0) {
		usbi_dbg("destroy device %d.%d", dev->bus_number, dev->device_address);

		if (usbi_backend->destroy_device)
			usbi_backend->destroy_device(dev);

		pthread_mutex_lock(&dev->ctx->usb_devs_lock);
		list_del(&dev->list);
		pthread_mutex_unlock(&dev->ctx->usb_devs_lock);

		free(dev);
	}
}

/** \ingroup dev
 * Open a device and obtain a device handle. A handle allows you to perform
 * I/O on the device in question.
 *
 * Internally, this function adds a reference to the device and makes it
 * available to you through libusb_get_device(). This reference is removed
 * during libusb_close().
 *
 * This is a non-blocking function; no requests are sent over the bus.
 *
 * \param dev the device to open
 * \param handle output location for the returned device handle pointer. Only
 * populated when the return code is 0.
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NO_MEM on memory allocation failure
 * \returns LIBUSB_ERROR_ACCESS if the user has insufficient permissions
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_open(libusb_device *dev, libusb_device_handle **handle)
{
	struct libusb_device_handle *_handle;
	size_t priv_size = usbi_backend->device_handle_priv_size;
	int r;
	usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);

	_handle = malloc(sizeof(*_handle) + priv_size);
	if (!_handle)
		return LIBUSB_ERROR_NO_MEM;

	r = pthread_mutex_init(&_handle->lock, NULL);
	if (r)
		return LIBUSB_ERROR_OTHER;

	_handle->dev = libusb_ref_device(dev);
	_handle->claimed_interfaces = 0;
	memset(&_handle->os_priv, 0, priv_size);

	r = usbi_backend->open(_handle);
	if (r < 0) {
		libusb_unref_device(dev);
		free(_handle);
		return r;
	}

	pthread_mutex_lock(&dev->ctx->open_devs_lock);
	list_add(&_handle->list, &dev->ctx->open_devs);
	pthread_mutex_unlock(&dev->ctx->open_devs_lock);
	*handle = _handle;
	return 0;
}

/** \ingroup dev
 * Convenience function for finding a device with a particular
 * <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
 * for those scenarios where you are using libusb to knock up a quick test
 * application - it allows you to avoid calling libusb_get_device_list() and
 * worrying about traversing/freeing the list.
 *
 * This function has limitations and is hence not intended for use in real
 * applications: if multiple devices have the same IDs it will only
 * give you the first one, etc.
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param vendor_id the idVendor value to search for
 * \param product_id the idProduct value to search for
 * \returns a handle for the first found device, or NULL on error or if the
 * device could not be found. */
API_EXPORTED libusb_device_handle *libusb_open_device_with_vid_pid(
	libusb_context *ctx, uint16_t vendor_id, uint16_t product_id)
{
	struct libusb_device **devs;
	struct libusb_device *found = NULL;
	struct libusb_device *dev;
	struct libusb_device_handle *handle = NULL;
	size_t i = 0;
	int r;

	if (libusb_get_device_list(ctx, &devs) < 0)
		return NULL;

	while ((dev = devs[i++]) != NULL) {
		struct libusb_device_descriptor desc;
		r = libusb_get_device_descriptor(dev, &desc);
		if (r < 0)
			goto out;
		if (desc.idVendor == vendor_id && desc.idProduct == product_id) {
			found = dev;
			break;
		}
	}

	if (found) {
		r = libusb_open(found, &handle);
		if (r < 0)
			handle = NULL;
	}

out:
	libusb_free_device_list(devs, 1);
	return handle;
}

static void do_close(struct libusb_device_handle *dev_handle)
{
	usbi_backend->close(dev_handle);
	libusb_unref_device(dev_handle->dev);
}

/** \ingroup dev
 * Close a device handle. Should be called on all open handles before your
 * application exits.
 *
 * Internally, this function destroys the reference that was added by
 * libusb_open() on the given device.
 *
 * This is a non-blocking function; no requests are sent over the bus.
 *
 * \param dev_handle the handle to close
 */
API_EXPORTED void libusb_close(libusb_device_handle *dev_handle)
{
	if (!dev_handle)
		return;
	usbi_dbg("");

	pthread_mutex_lock(&HANDLE_CTX(dev_handle)->open_devs_lock);
	list_del(&dev_handle->list);
	pthread_mutex_unlock(&HANDLE_CTX(dev_handle)->open_devs_lock);

	do_close(dev_handle);
	free(dev_handle);
}

/** \ingroup dev
 * Get the underlying device for a handle. This function does not modify
 * the reference count of the returned device, so do not feel compelled to
 * unreference it when you are done.
 * \param dev_handle a device handle
 * \returns the underlying device
 */
API_EXPORTED libusb_device *libusb_get_device(libusb_device_handle *dev_handle)
{
	return dev_handle->dev;
}

/** \ingroup dev
 * Determine the bConfigurationValue of the currently active configuration.
 *
 * You could formulate your own control request to obtain this information,
 * but this function has the advantage that it may be able to retrieve the
 * information from operating system caches (no I/O involved).
 *
 * If the OS does not cache this information, then this function will block
 * while a control transfer is submitted to retrieve the information.
 *
 * This function will return a value of 0 in the <tt>config</tt> output
 * parameter if the device is in unconfigured state.
 *
 * \param dev a device handle
 * \param config output location for the bConfigurationValue of the active
 * configuration (only valid for return code 0)
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_get_configuration(libusb_device_handle *dev,
	int *config)
{
	int r = LIBUSB_ERROR_NOT_SUPPORTED;

	usbi_dbg("");
	if (usbi_backend->get_configuration)
		r = usbi_backend->get_configuration(dev, config);

	if (r == LIBUSB_ERROR_NOT_SUPPORTED) {
		uint8_t tmp = 0;
		usbi_dbg("falling back to control message");
		r = libusb_control_transfer(dev, LIBUSB_ENDPOINT_IN,
			LIBUSB_REQUEST_GET_CONFIGURATION, 0, 0, &tmp, 1, 1000);
		if (r == 0) {
			usbi_err(HANDLE_CTX(dev), "zero bytes returned in ctrl transfer?");
			r = LIBUSB_ERROR_IO;
		} else if (r == 1) {
			r = 0;