core.c

最新的libusb库

			*config = tmp;
		} else {
			usbi_dbg("control failed, error %d", r);
		}
	}

	if (r == 0)
		usbi_dbg("active config %d", *config);

	return r;
}

/** \ingroup dev
 * Set the active configuration for a device.
 *
 * The operating system may or may not have already set an active
 * configuration on the device. It is up to your application to ensure the
 * correct configuration is selected before you attempt to claim interfaces
 * and perform other operations.
 * 
 * If you call this function on a device already configured with the selected
 * configuration, then this function will act as a lightweight device reset:
 * it will issue a SET_CONFIGURATION request using the current configuration,
 * causing most USB-related device state to be reset (altsetting reset to zero,
 * endpoint halts cleared, toggles reset).
 *
 * You cannot change/reset configuration if your application has claimed
 * interfaces - you should free them with libusb_release_interface() first.
 * You cannot change/reset configuration if other applications or drivers have
 * claimed interfaces.
 *
 * A configuration value of -1 will put the device in unconfigured state.
 * The USB specifications state that a configuration value of 0 does this,
 * however buggy devices exist which actually have a configuration 0.
 *
 * You should always use this function rather than formulating your own
 * SET_CONFIGURATION control request. This is because the underlying operating
 * system needs to know when such changes happen.
 *
 * This is a blocking function.
 *
 * \param dev a device handle
 * \param configuration the bConfigurationValue of the configuration you
 * wish to activate, or -1 if you wish to put the device in unconfigured state
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the requested configuration does not exist
 * \returns LIBUSB_ERROR_BUSY if interfaces are currently claimed
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_set_configuration(libusb_device_handle *dev,
	int configuration)
{
	usbi_dbg("configuration %d", configuration);
	return usbi_backend->set_configuration(dev, configuration);
}

/** \ingroup dev
 * Claim an interface on a given device handle. You must claim the interface
 * you wish to use before you can perform I/O on any of its endpoints.
 *
 * It is legal to attempt to claim an already-claimed interface, in which
 * case libusb just returns 0 without doing anything.
 *
 * Claiming of interfaces is a purely logical operation; it does not cause
 * any requests to be sent over the bus. Interface claiming is used to
 * instruct the underlying operating system that your application wishes
 * to take ownership of the interface.
 *
 * This is a non-blocking function.
 *
 * \param dev a device handle
 * \param interface_number the <tt>bInterfaceNumber</tt> of the interface you
 * wish to claim
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the requested interface does not exist
 * \returns LIBUSB_ERROR_BUSY if another program or driver has claimed the
 * interface
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns a LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_claim_interface(libusb_device_handle *dev,
	int interface_number)
{
	int r = 0;

	usbi_dbg("interface %d", interface_number);
	if (interface_number >= sizeof(dev->claimed_interfaces) * 8)
		return LIBUSB_ERROR_INVALID_PARAM;

	pthread_mutex_lock(&dev->lock);
	if (dev->claimed_interfaces & (1 << interface_number))
		goto out;

	r = usbi_backend->claim_interface(dev, interface_number);
	if (r == 0)
		dev->claimed_interfaces |= 1 << interface_number;

out:
	pthread_mutex_unlock(&dev->lock);
	return r;
}

/** \ingroup dev
 * Release an interface previously claimed with libusb_claim_interface(). You
 * should release all claimed interfaces before closing a device handle.
 *
 * This is a blocking function. A SET_INTERFACE control request will be sent
 * to the device, resetting interface state to the first alternate setting.
 *
 * \param dev a device handle
 * \param interface_number the <tt>bInterfaceNumber</tt> of the
 * previously-claimed interface
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_release_interface(libusb_device_handle *dev,
	int interface_number)
{
	int r;

	usbi_dbg("interface %d", interface_number);
	if (interface_number >= sizeof(dev->claimed_interfaces) * 8)
		return LIBUSB_ERROR_INVALID_PARAM;

	pthread_mutex_lock(&dev->lock);
	if (!(dev->claimed_interfaces & (1 << interface_number))) {
		r = LIBUSB_ERROR_NOT_FOUND;
		goto out;
	}

	r = usbi_backend->release_interface(dev, interface_number);
	if (r == 0)
		dev->claimed_interfaces &= ~(1 << interface_number);

out:
	pthread_mutex_unlock(&dev->lock);
	return r;
}

/** \ingroup dev
 * Activate an alternate setting for an interface. The interface must have
 * been previously claimed with libusb_claim_interface().
 *
 * You should always use this function rather than formulating your own
 * SET_INTERFACE control request. This is because the underlying operating
 * system needs to know when such changes happen.
 *
 * This is a blocking function.
 *
 * \param dev a device handle
 * \param interface_number the <tt>bInterfaceNumber</tt> of the
 * previously-claimed interface
 * \param alternate_setting the <tt>bAlternateSetting</tt> of the alternate
 * setting to activate
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed, or the
 * requested alternate setting does not exist
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_set_interface_alt_setting(libusb_device_handle *dev,
	int interface_number, int alternate_setting)
{
	usbi_dbg("interface %d altsetting %d",
		interface_number, alternate_setting);
	if (interface_number >= sizeof(dev->claimed_interfaces) * 8)
		return LIBUSB_ERROR_INVALID_PARAM;

	pthread_mutex_lock(&dev->lock);
	if (!(dev->claimed_interfaces & (1 << interface_number))) {
		pthread_mutex_unlock(&dev->lock);	
		return LIBUSB_ERROR_NOT_FOUND;
	}
	pthread_mutex_unlock(&dev->lock);

	return usbi_backend->set_interface_altsetting(dev, interface_number,
		alternate_setting);
}

/** \ingroup dev
 * Clear the halt/stall condition for an endpoint. Endpoints with halt status
 * are unable to receive or transmit data until the halt condition is stalled.
 *
 * You should cancel all pending transfers before attempting to clear the halt
 * condition.
 *
 * This is a blocking function.
 *
 * \param dev a device handle
 * \param endpoint the endpoint to clear halt status
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_clear_halt(libusb_device_handle *dev,
	unsigned char endpoint)
{
	usbi_dbg("endpoint %x", endpoint);
	return usbi_backend->clear_halt(dev, endpoint);
}

/** \ingroup dev
 * Perform a USB port reset to reinitialize a device. The system will attempt
 * to restore the previous configuration and alternate settings after the
 * reset has completed.
 *
 * If the reset fails, the descriptors change, or the previous state cannot be
 * restored, the device will appear to be disconnected and reconnected. This
 * means that the device handle is no longer valid (you should close it) and
 * rediscover the device. A return code of LIBUSB_ERROR_NOT_FOUND indicates
 * when this is the case.
 *
 * This is a blocking function which usually incurs a noticeable delay.
 *
 * \param dev a handle of the device to reset
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the
 * device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 */
API_EXPORTED int libusb_reset_device(libusb_device_handle *dev)
{
	usbi_dbg("");
	return usbi_backend->reset_device(dev);
}

/** \ingroup dev
 * Determine if a kernel driver is active on an interface. If a kernel driver
 * is active, you cannot claim the interface, and libusb will be unable to
 * perform I/O.
 *
 * \param dev a device handle
 * \param interface the interface to check
 * \returns 0 if no kernel driver is active
 * \returns 1 if a kernel driver is active
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 * \see libusb_detach_kernel_driver()
 */
API_EXPORTED int libusb_kernel_driver_active(libusb_device_handle *dev,
	int interface)
{
	usbi_dbg("interface %d", interface);
	if (usbi_backend->kernel_driver_active)
		return usbi_backend->kernel_driver_active(dev, interface);
	else
		return LIBUSB_ERROR_NOT_SUPPORTED;
}

/** \ingroup dev
 * Detach a kernel driver from an interface. If successful, you will then be
 * able to claim the interface and perform I/O.
 *
 * \param dev a device handle
 * \param interface the interface to detach the driver from
 * \returns 0 on success
 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
 * \returns another LIBUSB_ERROR code on other failure
 * \see libusb_kernel_driver_active()
 */
API_EXPORTED int libusb_detach_kernel_driver(libusb_device_handle *dev,
	int interface)
{
	usbi_dbg("interface %d", interface);
	if (usbi_backend->detach_kernel_driver)
		return usbi_backend->detach_kernel_driver(dev, interface);
	else
		return LIBUSB_ERROR_NOT_SUPPORTED;
}

/** \ingroup lib
 * Set message verbosity.
 *  - Level 0: no messages ever printed by the library (default)
 *  - Level 1: error messages are printed to stderr
 *  - Level 2: warning and error messages are printed to stderr
 *  - Level 3: informational messages are printed to stdout, warning and error
 *    messages are printed to stderr
 *
 * The default level is 0, which means no messages are ever printed. If you
 * choose to increase the message verbosity level, ensure that your
 * application does not close the stdout/stderr file descriptors.
 *
 * You are advised to set level 3. libusb is conservative with it's message
 * logging and most of the time, will only log messages that explain error
 * conditions and other oddities. This will help you debug your software.
 *
 * If the LIBUSB_DEBUG environment variable was set when libusb was
 * initialized, this function does nothing: the message verbosity is fixed
 * to the value in the environment variable.
 *
 * If libusb was compiled without any message logging, this function does
 * nothing: you'll never get any messages.
 *
 * If libusb was compiled with verbose debug message logging, this function
 * does nothing: you'll always get messages from all levels.
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param level debug level to set
 */
API_EXPORTED void libusb_set_debug(libusb_context *ctx, int level)
{
	USBI_GET_CONTEXT(ctx);
	if (!ctx->debug_fixed)
		ctx->debug = level;
}

/** \ingroup lib
 * Initialize libusb. This function must be called before calling any other
 * libusb function.
 * \param context Optional output location for context pointer.
 * Only valid on return code 0.
 * \returns 0 on success, or a LIBUSB_ERROR code on failure
 */
API_EXPORTED int libusb_init(libusb_context **context)
{
	char *dbg = getenv("LIBUSB_DEBUG");
	struct libusb_context *ctx = malloc(sizeof(*ctx));

	if (!ctx)
		return LIBUSB_ERROR_NO_MEM;
	memset(ctx, 0, sizeof(*ctx));

	if (dbg) {
		ctx->debug = atoi(dbg);
		if (ctx->debug)
			ctx->debug_fixed = 1;
	}

	usbi_dbg("");
	if (usbi_backend->init) {
		int r = usbi_backend->init(ctx);
		if (r) {
			free(ctx);
			return r;
		}
	}

	pthread_mutex_init(&ctx->usb_devs_lock, NULL);
	pthread_mutex_init(&ctx->open_devs_lock, NULL);
	list_init(&ctx->usb_devs);
	list_init(&ctx->open_devs);
	usbi_io_init(ctx);

	pthread_mutex_lock(&default_context_lock);
	if (!usbi_default_context) {
		usbi_dbg("created default context");
		usbi_default_context = ctx;
	}
	pthread_mutex_unlock(&default_context_lock);

	if (context)
		*context = ctx;
	return 0;
}

/** \ingroup lib
 * Deinitialize libusb. Should be called after closing all open devices and
 * before your application terminates.
 * \param ctx the context to deinitialize, or NULL for the default context
 */
API_EXPORTED void libusb_exit(struct libusb_context *ctx)
{
	USBI_GET_CONTEXT(ctx);
	usbi_dbg("");

	pthread_mutex_lock(&ctx->open_devs_lock);
	if (!list_empty(&ctx->open_devs)) {
		struct libusb_device_handle *devh;
		struct libusb_device_handle *tmp;

		usbi_dbg("naughty app left some devices open!");
		list_for_each_entry_safe(devh, tmp, &ctx->open_devs, list) {
			list_del(&devh->list);
			do_close(devh);
			free(devh);
		}
	}
	pthread_mutex_unlock(&ctx->open_devs_lock);

	if (usbi_backend->exit)
		usbi_backend->exit();
	
	pthread_mutex_lock(&default_context_lock);
	if (ctx == usbi_default_context) {
		usbi_dbg("freeing default context");
		usbi_default_context = NULL;
	}
	pthread_mutex_unlock(&default_context_lock);

	free(ctx);
}

void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
	const char *function, const char *format, ...)
{
	va_list args;
	FILE *stream = stdout;
	const char *prefix;

#ifndef ENABLE_DEBUG_LOGGING
	USBI_GET_CONTEXT(ctx);
	if (!ctx->debug)
		return;
	if (level == LOG_LEVEL_WARNING && ctx->debug < 2)
		return;
	if (level == LOG_LEVEL_INFO && ctx->debug < 3)
		return;
#endif

	switch (level) {
	case LOG_LEVEL_INFO:
		prefix = "info";
		break;
	case LOG_LEVEL_WARNING:
		stream = stderr;
		prefix = "warning";
		break;
	case LOG_LEVEL_ERROR:
		stream = stderr;
		prefix = "error";
		break;
	case LOG_LEVEL_DEBUG:
		stream = stderr;
		prefix = "debug";
		break;
	default:
		stream = stderr;
		prefix = "unknown";
		break;
	}

	fprintf(stream, "libusb:%s [%s] ", prefix, function);

	va_start (args, format);
	vfprintf(stream, format, args);
	va_end (args);

	fprintf(stream, "\n");
}