Revert 129069 - Import libusb 1.0.9-rc3 into third_party.

third_party/libusb/libusb/core.c

Index: third_party/libusb/libusb/core.c
===================================================================
--- third_party/libusb/libusb/core.c	(revision 129100)
+++ third_party/libusb/libusb/core.c	(working copy)
@@ -1,1781 +0,0 @@
-/*
- * Core functions for libusb
- * Copyright (C) 2007-2008 Daniel Drake <dsd@gentoo.org>
- * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <config.h>
-
-#include <errno.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/types.h>
-
-#include "libusbi.h"
-
-#if defined(OS_LINUX)
-const struct usbi_os_backend * const usbi_backend = &linux_usbfs_backend;
-#elif defined(OS_DARWIN)
-const struct usbi_os_backend * const usbi_backend = &darwin_backend;
-#elif defined(OS_WINDOWS)
-const struct usbi_os_backend * const usbi_backend = &windows_backend;
-#else
-#error "Unsupported OS"
-#endif
-
-struct libusb_context *usbi_default_context = NULL;
-static int default_context_refcnt = 0;
-static usbi_mutex_static_t default_context_lock = USBI_MUTEX_INITIALIZER;
-
-/**
- * \mainpage libusb-1.0 API Reference
- *
- * \section intro Introduction
- *
- * libusb is an open source library that allows you to communicate with USB
- * devices from userspace. For more info, see the
- * <a href="http://libusb.sourceforge.net">libusb homepage</a>.
- *
- * This documentation is aimed at application developers wishing to
- * communicate with USB peripherals from their own software. After reviewing
- * this documentation, feedback and questions can be sent to the
- * <a href="http://sourceforge.net/mail/?group_id=1674">libusb-devel mailing
- * list</a>.
- *
- * This documentation assumes knowledge of how to operate USB devices from
- * a software standpoint (descriptors, configurations, interfaces, endpoints,
- * control/bulk/interrupt/isochronous transfers, etc). Full information
- * can be found in the <a href="http://www.usb.org/developers/docs/">USB 2.0
- * Specification</a> which is available for free download. You can probably
- * find less verbose introductions by searching the web.
- *
- * \section features Library features
- *
- * - All transfer types supported (control/bulk/interrupt/isochronous)
- * - 2 transfer interfaces:
- *    -# Synchronous (simple)
- *    -# Asynchronous (more complicated, but more powerful)
- * - Thread safe (although the asynchronous interface means that you
- *   usually won't need to thread)
- * - Lightweight with lean API
- * - Compatible with libusb-0.1 through the libusb-compat-0.1 translation layer
- *
- * \section gettingstarted Getting Started
- *
- * To begin reading the API documentation, start with the Modules page which
- * links to the different categories of libusb's functionality.
- *
- * One decision you will have to make is whether to use the synchronous
- * or the asynchronous data transfer interface. The \ref io documentation
- * provides some insight into this topic.
- *
- * Some example programs can be found in the libusb source distribution under
- * the "examples" subdirectory. The libusb homepage includes a list of
- * real-life project examples which use libusb.
- *
- * \section errorhandling Error handling
- *
- * libusb functions typically return 0 on success or a negative error code
- * on failure. These negative error codes relate to LIBUSB_ERROR constants
- * which are listed on the \ref misc "miscellaneous" documentation page.
- *
- * \section msglog Debug message logging
- *
- * libusb does not log any messages by default. Your application is therefore
- * free to close stdout/stderr and those descriptors may be reused without
- * worry.
- *
- * The libusb_set_debug() function can be used to enable stdout/stderr logging
- * of certain messages. Under standard configuration, libusb doesn't really
- * log much at all, so you are advised to use this function to enable all
- * error/warning/informational messages. It will help you debug problems with
- * your software.
- *
- * The logged messages are unstructured. There is no one-to-one correspondence
- * between messages being logged and success or failure return codes from
- * libusb functions. There is no format to the messages, so you should not
- * try to capture or parse them. They are not and will not be localized.
- * These messages are not suitable for being passed to your application user;
- * instead, you should interpret the error codes returned from libusb functions
- * and provide appropriate notification to the user. The messages are simply
- * there to aid you as a programmer, and if you're confused because you're
- * getting a strange error code from a libusb function, enabling message
- * logging may give you a suitable explanation.
- *
- * The LIBUSB_DEBUG environment variable can be used to enable message logging
- * at run-time. This environment variable should be set to a number, which is
- * interpreted the same as the libusb_set_debug() parameter. When this
- * environment variable is set, the message logging verbosity level is fixed
- * and libusb_set_debug() effectively does nothing.
- *
- * libusb can be compiled without any logging functions, useful for embedded
- * systems. In this case, libusb_set_debug() and the LIBUSB_DEBUG environment
- * variable have no effects.
- *
- * libusb can also be compiled with verbose debugging messages. When the
- * library is compiled in this way, all messages of all verbosities are always
- * logged.  libusb_set_debug() and the LIBUSB_DEBUG environment variable have
- * no effects.
- *
- * \section remarks Other remarks
- *
- * libusb does have imperfections. The \ref caveats "caveats" page attempts
- * to document these.
- */
-
-/**
- * \page caveats Caveats
- *
- * \section devresets Device resets
- *
- * The libusb_reset_device() function allows you to reset a device. If your
- * program has to call such a function, it should obviously be aware that
- * the reset will cause device state to change (e.g. register values may be
- * reset).
- *
- * The problem is that any other program could reset the device your program
- * is working with, at any time. libusb does not offer a mechanism to inform
- * you when this has happened, so if someone else resets your device it will
- * not be clear to your own program why the device state has changed.
- *
- * Ultimately, this is a limitation of writing drivers in userspace.
- * Separation from the USB stack in the underlying kernel makes it difficult
- * for the operating system to deliver such notifications to your program.
- * The Linux kernel USB stack allows such reset notifications to be delivered
- * to in-kernel USB drivers, but it is not clear how such notifications could
- * be delivered to second-class drivers that live in userspace.
- *
- * \section blockonly Blocking-only functionality
- *
- * The functionality listed below is only available through synchronous,
- * blocking functions. There are no asynchronous/non-blocking alternatives,
- * and no clear ways of implementing these.
- *
- * - Configuration activation (libusb_set_configuration())
- * - Interface/alternate setting activation (libusb_set_interface_alt_setting())
- * - Releasing of interfaces (libusb_release_interface())
- * - Clearing of halt/stall condition (libusb_clear_halt())
- * - Device resets (libusb_reset_device())
- *
- * \section nohotplug No hotplugging
- *
- * libusb-1.0 lacks functionality for providing notifications of when devices
- * are added or removed. This functionality is planned to be implemented
- * for libusb-1.1.
- *
- * That said, there is basic disconnection handling for open device handles:
- *  - If there are ongoing transfers, libusb's handle_events loop will detect
- *    disconnections and complete ongoing transfers with the
- *    LIBUSB_TRANSFER_NO_DEVICE status code.
- *  - Many functions such as libusb_set_configuration() return the special
- *    LIBUSB_ERROR_NO_DEVICE error code when the device has been disconnected.
- *
- * \section configsel Configuration selection and handling
- *
- * When libusb presents a device handle to an application, there is a chance
- * that the corresponding device may be in unconfigured state. For devices
- * with multiple configurations, there is also a chance that the configuration
- * currently selected is not the one that the application wants to use.
- *
- * The obvious solution is to add a call to libusb_set_configuration() early
- * on during your device initialization routines, but there are caveats to
- * be aware of:
- * -# If the device is already in the desired configuration, calling
- *    libusb_set_configuration() using the same configuration value will cause
- *    a lightweight device reset. This may not be desirable behaviour.
- * -# libusb will be unable to change configuration if the device is in
- *    another configuration and other programs or drivers have claimed
- *    interfaces under that configuration.
- * -# In the case where the desired configuration is already active, libusb
- *    may not even be able to perform a lightweight device reset. For example,
- *    take my USB keyboard with fingerprint reader: I'm interested in driving
- *    the fingerprint reader interface through libusb, but the kernel's
- *    USB-HID driver will almost always have claimed the keyboard interface.
- *    Because the kernel has claimed an interface, it is not even possible to
- *    perform the lightweight device reset, so libusb_set_configuration() will
- *    fail. (Luckily the device in question only has a single configuration.)
- *
- * One solution to some of the above problems is to consider the currently
- * active configuration. If the configuration we want is already active, then
- * we don't have to select any configuration:
-\code
-cfg = libusb_get_configuration(dev);
-if (cfg != desired)
-	libusb_set_configuration(dev, desired);
-\endcode
- *
- * This is probably suitable for most scenarios, but is inherently racy:
- * another application or driver may change the selected configuration
- * <em>after</em> the libusb_get_configuration() call.
- *
- * Even in cases where libusb_set_configuration() succeeds, consider that other
- * applications or drivers may change configuration after your application
- * calls libusb_set_configuration().
- *
- * One possible way to lock your device into a specific configuration is as
- * follows:
- * -# Set the desired configuration (or use the logic above to realise that
- *    it is already in the desired configuration)
- * -# Claim the interface that you wish to use
- * -# Check that the currently active configuration is the one that you want
- *    to use.
- *
- * The above method works because once an interface is claimed, no application
- * or driver is able to select another configuration.
- *
- * \section earlycomp Early transfer completion
- *
- * NOTE: This section is currently Linux-centric. I am not sure if any of these
- * considerations apply to Darwin or other platforms.
- *
- * When a transfer completes early (i.e. when less data is received/sent in
- * any one packet than the transfer buffer allows for) then libusb is designed
- * to terminate the transfer immediately, not transferring or receiving any
- * more data unless other transfers have been queued by the user.
- *
- * On legacy platforms, libusb is unable to do this in all situations. After
- * the incomplete packet occurs, "surplus" data may be transferred. Prior to
- * libusb v1.0.2, this information was lost (and for device-to-host transfers,
- * the corresponding data was discarded). As of libusb v1.0.3, this information
- * is kept (the data length of the transfer is updated) and, for device-to-host
- * transfers, any surplus data was added to the buffer. Still, this is not
- * a nice solution because it loses the information about the end of the short
- * packet, and the user probably wanted that surplus data to arrive in the next
- * logical transfer.
- *
- * A previous workaround was to only ever submit transfers of size 16kb or
- * less.
- *
- * As of libusb v1.0.4 and Linux v2.6.32, this is fixed. A technical
- * explanation of this issue follows.
- *
- * When you ask libusb to submit a bulk transfer larger than 16kb in size,
- * libusb breaks it up into a number of smaller subtransfers. This is because
- * the usbfs kernel interface only accepts transfers of up to 16kb in size.
- * The subtransfers are submitted all at once so that the kernel can queue
- * them at the hardware level, therefore maximizing bus throughput.
- *
- * On legacy platforms, this caused problems when transfers completed early.
- * Upon this event, the kernel would terminate all further packets in that
- * subtransfer (but not any following ones). libusb would note this event and
- * immediately cancel any following subtransfers that had been queued,
- * but often libusb was not fast enough, and the following subtransfers had
- * started before libusb got around to cancelling them.
- *
- * Thanks to an API extension to usbfs, this is fixed with recent kernel and
- * libusb releases. The solution was to allow libusb to communicate to the
- * kernel where boundaries occur between logical libusb-level transfers. When
- * a short transfer (or other error) occurs, the kernel will cancel all the
- * subtransfers until the boundary without allowing those transfers to start.
- */
-
-/**
- * \page contexts Contexts
- *
- * It is possible that libusb may be used simultaneously from two independent
- * libraries linked into the same executable. For example, if your application
- * has a plugin-like system which allows the user to dynamically load a range
- * of modules into your program, it is feasible that two independently
- * developed modules may both use libusb.
- *
- * libusb is written to allow for these multiple user scenarios. The two
- * "instances" of libusb will not interfere: libusb_set_debug() calls
- * from one user will not affect the same settings for other users, other
- * users can continue using libusb after one of them calls libusb_exit(), etc.
- *
- * This is made possible through libusb's <em>context</em> concept. When you
- * call libusb_init(), you are (optionally) given a context. You can then pass
- * this context pointer back into future libusb functions.
- *
- * In order to keep things simple for more simplistic applications, it is
- * legal to pass NULL to all functions requiring a context pointer (as long as
- * you're sure no other code will attempt to use libusb from the same process).
- * When you pass NULL, the default context will be used. The default context
- * is created the first time a process calls libusb_init() when no other
- * context is alive. Contexts are destroyed during libusb_exit().
- *
- * The default context is reference-counted and can be shared. That means that
- * if libusb_init(NULL) is called twice within the same process, the two
- * users end up sharing the same context. The deinitialization and freeing of
- * the default context will only happen when the last user calls libusb_exit().
- * In other words, the default context is created and initialized when its
- * reference count goes from 0 to 1, and is deinitialized and destroyed when
- * its reference count goes from 1 to 0.
- *
- * You may be wondering why only a subset of libusb functions require a
- * context pointer in their function definition. Internally, libusb stores
- * context pointers in other objects (e.g. libusb_device instances) and hence
- * can infer the context from those objects.
- */
-
-/**
- * @defgroup lib Library initialization/deinitialization
- * This page details how to initialize and deinitialize libusb. Initialization
- * must be performed before using any libusb functionality, and similarly you
- * must not call any libusb functions after deinitialization.
- */
-
-/**
- * @defgroup dev Device handling and enumeration
- * The functionality documented below is designed to help with the following
- * operations:
- * - Enumerating the USB devices currently attached to the system
- * - Choosing a device to operate from your software
- * - Opening and closing the chosen device
- *
- * \section nutshell In a nutshell...
- *
- * The description below really makes things sound more complicated than they
- * actually are. The following sequence of function calls will be suitable
- * for almost all scenarios and does not require you to have such a deep
- * understanding of the resource management issues:
- * \code
-// discover devices
-libusb_device **list;
-libusb_device *found = NULL;
-ssize_t cnt = libusb_get_device_list(NULL, &list);
-ssize_t i = 0;
-int err = 0;
-if (cnt < 0)
-	error();
-
-for (i = 0; i < cnt; i++) {
-	libusb_device *device = list[i];
-	if (is_interesting(device)) {
-		found = device;
-		break;
-	}
-}
-
-if (found) {
-	libusb_device_handle *handle;
-
-	err = libusb_open(found, &handle);
-	if (err)
-		error();
-	// etc
-}
-
-libusb_free_device_list(list, 1);
-\endcode
- *
- * The two important points:
- * - You asked libusb_free_device_list() to unreference the devices (2nd
- *   parameter)
- * - You opened the device before freeing the list and unreferencing the
- *   devices
- *
- * If you ended up with a handle, you can now proceed to perform I/O on the
- * device.
- *
- * \section devshandles Devices and device handles
- * libusb has a concept of a USB device, represented by the
- * \ref libusb_device opaque type. A device represents a USB device that
- * is currently or was previously connected to the system. Using a reference
- * to a device, you can determine certain information about the device (e.g.
- * you can read the descriptor data).
- *
- * The libusb_get_device_list() function can be used to obtain a list of
- * devices currently connected to the system. This is known as device
- * discovery.
- *
- * Just because you have a reference to a device does not mean it is
- * necessarily usable. The device may have been unplugged, you may not have
- * permission to operate such device, or another program or driver may be
- * using the device.
- *
- * When you've found a device that you'd like to operate, you must ask
- * libusb to open the device using the libusb_open() function. Assuming
- * success, libusb then returns you a <em>device handle</em>
- * (a \ref libusb_device_handle pointer). All "real" I/O operations then
- * operate on the handle rather than the original device pointer.
- *
- * \section devref Device discovery and reference counting
- *
- * Device discovery (i.e. calling libusb_get_device_list()) returns a
- * freshly-allocated list of devices. The list itself must be freed when
- * you are done with it. libusb also needs to know when it is OK to free
- * the contents of the list - the devices themselves.
- *
- * To handle these issues, libusb provides you with two separate items:
- * - A function to free the list itself
- * - A reference counting system for the devices inside
- *
- * New devices presented by the libusb_get_device_list() function all have a
- * reference count of 1. You can increase and decrease reference count using
- * libusb_ref_device() and libusb_unref_device(). A device is destroyed when
- * its reference count reaches 0.
- *
- * With the above information in mind, the process of opening a device can
- * be viewed as follows:
- * -# Discover devices using libusb_get_device_list().
- * -# Choose the device that you want to operate, and call libusb_open().
- * -# Unref all devices in the discovered device list.
- * -# Free the discovered device list.
- *
- * The order is important - you must not unreference the device before
- * attempting to open it, because unreferencing it may destroy the device.
- *
- * For convenience, the libusb_free_device_list() function includes a
- * parameter to optionally unreference all the devices in the list before
- * freeing the list itself. This combines steps 3 and 4 above.
- *
- * As an implementation detail, libusb_open() actually adds a reference to
- * the device in question. This is because the device remains available
- * through the handle via libusb_get_device(). The reference is deleted during
- * libusb_close().
- */
-
-/** @defgroup misc Miscellaneous */
-
-/* we traverse usbfs without knowing how many devices we are going to find.
- * so we create this discovered_devs model which is similar to a linked-list
- * which grows when required. it can be freed once discovery has completed,
- * eliminating the need for a list node in the libusb_device structure
- * itself. */
-#define DISCOVERED_DEVICES_SIZE_STEP 8
-
-static struct discovered_devs *discovered_devs_alloc(void)
-{
-	struct discovered_devs *ret =
-		malloc(sizeof(*ret) + (sizeof(void *) * DISCOVERED_DEVICES_SIZE_STEP));
-
-	if (ret) {
-		ret->len = 0;
-		ret->capacity = DISCOVERED_DEVICES_SIZE_STEP;
-	}
-	return ret;
-}
-
-/* append a device to the discovered devices collection. may realloc itself,
- * returning new discdevs. returns NULL on realloc failure. */
-struct discovered_devs *discovered_devs_append(
-	struct discovered_devs *discdevs, struct libusb_device *dev)
-{
-	size_t len = discdevs->len;
-	size_t capacity;
-
-	/* if there is space, just append the device */
-	if (len < discdevs->capacity) {
-		discdevs->devices[len] = libusb_ref_device(dev);
-		discdevs->len++;
-		return discdevs;
-	}
-
-	/* exceeded capacity, need to grow */
-	usbi_dbg("need to increase capacity");
-	capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
-	discdevs = realloc(discdevs,
-		sizeof(*discdevs) + (sizeof(void *) * capacity));
-	if (discdevs) {
-		discdevs->capacity = capacity;
-		discdevs->devices[len] = libusb_ref_device(dev);
-		discdevs->len++;
-	}
-
-	return discdevs;
-}
-
-static void discovered_devs_free(struct discovered_devs *discdevs)
-{
-	size_t i;
-
-	for (i = 0; i < discdevs->len; i++)
-		libusb_unref_device(discdevs->devices[i]);
-
-	free(discdevs);
-}
-
-/* Allocate a new device with a specific session ID. The returned device has
- * a reference count of 1. */
-struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
-	unsigned long session_id)
-{
-	size_t priv_size = usbi_backend->device_priv_size;
-	struct libusb_device *dev = calloc(1, sizeof(*dev) + priv_size);
-	int r;
-
-	if (!dev)
-		return NULL;
-
-	r = usbi_mutex_init(&dev->lock, NULL);
-	if (r) {
-		free(dev);
-		return NULL;
-	}
-
-	dev->ctx = ctx;
-	dev->refcnt = 1;
-	dev->session_data = session_id;
-	dev->speed = LIBUSB_SPEED_UNKNOWN;
-	memset(&dev->os_priv, 0, priv_size);
-
-	usbi_mutex_lock(&ctx->usb_devs_lock);
-	list_add(&dev->list, &ctx->usb_devs);
-	usbi_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 (0 == num_configurations)
-		usbi_dbg("zero configurations, maybe an unauthorized device");
-
-	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;
-
-	usbi_mutex_lock(&ctx->usb_devs_lock);
-	list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device)
-		if (dev->session_data == session_id) {
-			ret = dev;
-			break;
-		}
-	usbi_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 any
- * \ref libusb_error according to errors encountered by the backend.
- */
-ssize_t API_EXPORTED libusb_get_device_list(libusb_context *ctx,
-	libusb_device ***list)
-{
-	struct discovered_devs *discdevs = discovered_devs_alloc();
-	struct libusb_device **ret;
-	int r = 0;
-	ssize_t i, 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
- */
-void API_EXPORTED 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
- */
-uint8_t API_EXPORTED 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
- */
-uint8_t API_EXPORTED libusb_get_device_address(libusb_device *dev)
-{
-	return dev->device_address;
-}
-
-/** \ingroup dev
- * Get the negotiated connection speed for a device.
- * \param dev a device
- * \returns a \ref libusb_speed code, where LIBUSB_SPEED_UNKNOWN means that
- * the OS doesn't know or doesn't support returning the negotiated speed.
- */
-int API_EXPORTED libusb_get_device_speed(libusb_device *dev)
-{
-	return dev->speed;
-}
-
-static const struct libusb_endpoint_descriptor *find_endpoint(
-	struct libusb_config_descriptor *config, unsigned char endpoint)
-{
-	int iface_idx;
-	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)
-					return ep;
-			}
-		}
-	}
-	return NULL;
-}
-
-/** \ingroup dev
- * Convenience function to retrieve the wMaxPacketSize value for a particular
- * endpoint in the active device configuration.
- *
- * This function was originally intended to be of assistance when setting up
- * isochronous transfers, but a design mistake resulted in this function
- * instead. It simply returns the wMaxPacketSize value without considering
- * its contents. If you're dealing with isochronous transfers, you probably
- * want libusb_get_max_iso_packet_size() instead.
- *
- * \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
- */
-int API_EXPORTED libusb_get_max_packet_size(libusb_device *dev,
-	unsigned char endpoint)
-{
-	struct libusb_config_descriptor *config;
-	const struct libusb_endpoint_descriptor *ep;
-	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;
-	}
-
-	ep = find_endpoint(config, endpoint);
-	if (!ep)
-		return LIBUSB_ERROR_NOT_FOUND;
-
-	r = ep->wMaxPacketSize;
-	libusb_free_config_descriptor(config);
-	return r;
-}
-
-/** \ingroup dev
- * Calculate the maximum packet size which a specific endpoint is capable is
- * sending or receiving in the duration of 1 microframe
- *
- * Only the active configution is examined. The calculation is based on the
- * wMaxPacketSize field in the endpoint descriptor as described in section
- * 9.6.6 in the USB 2.0 specifications.
- *
- * If acting on an isochronous or interrupt endpoint, this function will
- * multiply the value found in bits 0:10 by the number of transactions per
- * microframe (determined by bits 11:12). Otherwise, this function just
- * returns the numeric value found in bits 0:10.
- *
- * This function is useful for setting up isochronous transfers, for example
- * you might pass the return value from this function to
- * libusb_set_iso_packet_lengths() in order to set the length field of every
- * isochronous packet in a transfer.
- *
- * Since v1.0.3.
- *
- * \param dev a device
- * \param endpoint address of the endpoint in question
- * \returns the maximum packet size which can be sent/received on this endpoint
- * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
- * \returns LIBUSB_ERROR_OTHER on other failure
- */
-int API_EXPORTED libusb_get_max_iso_packet_size(libusb_device *dev,
-	unsigned char endpoint)
-{
-	struct libusb_config_descriptor *config;
-	const struct libusb_endpoint_descriptor *ep;
-	enum libusb_transfer_type ep_type;
-	uint16_t val;
-	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;
-	}
-
-	ep = find_endpoint(config, endpoint);
-	if (!ep)
-		return LIBUSB_ERROR_NOT_FOUND;
-
-	val = ep->wMaxPacketSize;
-	ep_type = ep->bmAttributes & 0x3;
-	libusb_free_config_descriptor(config);
-
-	r = val & 0x07ff;
-	if (ep_type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
-			|| ep_type == LIBUSB_TRANSFER_TYPE_INTERRUPT)
-		r *= (1 + ((val >> 11) & 3));
-	return r;
-}
-
-/** \ingroup dev
- * Increment the reference count of a device.
- * \param dev the device to reference
- * \returns the same device
- */
-DEFAULT_VISIBILITY
-libusb_device * LIBUSB_CALL libusb_ref_device(libusb_device *dev)
-{
-	usbi_mutex_lock(&dev->lock);
-	dev->refcnt++;
-	usbi_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
- */
-void API_EXPORTED libusb_unref_device(libusb_device *dev)
-{
-	int refcnt;
-
-	if (!dev)
-		return;
-
-	usbi_mutex_lock(&dev->lock);
-	refcnt = --dev->refcnt;
-	usbi_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);
-
-		usbi_mutex_lock(&dev->ctx->usb_devs_lock);
-		list_del(&dev->list);
-		usbi_mutex_unlock(&dev->ctx->usb_devs_lock);
-
-		usbi_mutex_destroy(&dev->lock);
-		free(dev);
-	}
-}
-
-/*
- * Interrupt the iteration of the event handling thread, so that it picks
- * up the new fd.
- */
-void usbi_fd_notification(struct libusb_context *ctx)
-{
-	unsigned char dummy = 1;
-	ssize_t r;
-
-	if (ctx == NULL)
-		return;
-
-	/* record that we are messing with poll fds */
-	usbi_mutex_lock(&ctx->pollfd_modify_lock);
-	ctx->pollfd_modify++;
-	usbi_mutex_unlock(&ctx->pollfd_modify_lock);
-
-	/* write some data on control pipe to interrupt event handlers */
-	r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
-	if (r <= 0) {
-		usbi_warn(ctx, "internal signalling write failed");
-		usbi_mutex_lock(&ctx->pollfd_modify_lock);
-		ctx->pollfd_modify--;
-		usbi_mutex_unlock(&ctx->pollfd_modify_lock);
-		return;
-	}
-
-	/* take event handling lock */
-	libusb_lock_events(ctx);
-
-	/* read the dummy data */
-	r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
-	if (r <= 0)
-		usbi_warn(ctx, "internal signalling read failed");
-
-	/* we're done with modifying poll fds */
-	usbi_mutex_lock(&ctx->pollfd_modify_lock);
-	ctx->pollfd_modify--;
-	usbi_mutex_unlock(&ctx->pollfd_modify_lock);
-
-	/* Release event handling lock and wake up event waiters */
-	libusb_unlock_events(ctx);
-}
-
-/** \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
- */
-int API_EXPORTED libusb_open(libusb_device *dev,
-	libusb_device_handle **handle)
-{
-	struct libusb_context *ctx = DEVICE_CTX(dev);
-	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 = usbi_mutex_init(&_handle->lock, NULL);
-	if (r) {
-		free(_handle);
-		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) {
-		usbi_dbg("open %d.%d returns %d", dev->bus_number, dev->device_address, r);
-		libusb_unref_device(dev);
-		usbi_mutex_destroy(&_handle->lock);
-		free(_handle);
-		return r;
-	}
-
-	usbi_mutex_lock(&ctx->open_devs_lock);
-	list_add(&_handle->list, &ctx->open_devs);
-	usbi_mutex_unlock(&ctx->open_devs_lock);
-	*handle = _handle;
-
-	/* At this point, we want to interrupt any existing event handlers so
-	 * that they realise the addition of the new device's poll fd. One
-	 * example when this is desirable is if the user is running a separate
-	 * dedicated libusb events handling thread, which is running with a long
-	 * or infinite timeout. We want to interrupt that iteration of the loop,
-	 * so that it picks up the new fd, and then continues. */
-	usbi_fd_notification(ctx);
-
-	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. */
-DEFAULT_VISIBILITY
-libusb_device_handle * LIBUSB_CALL 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_context *ctx,
-	struct libusb_device_handle *dev_handle)
-{
-	struct usbi_transfer *itransfer;
-	struct usbi_transfer *tmp;
-
-	libusb_lock_events(ctx);
-
-	/* remove any transfers in flight that are for this device */
-	usbi_mutex_lock(&ctx->flying_transfers_lock);
-
-	/* safe iteration because transfers may be being deleted */
-	list_for_each_entry_safe(itransfer, tmp, &ctx->flying_transfers, list, struct usbi_transfer) {
-		struct libusb_transfer *transfer =
-		        USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-
-		if (transfer->dev_handle != dev_handle)
-			continue;
-
-		if (!(itransfer->flags & USBI_TRANSFER_DEVICE_DISAPPEARED)) {
-			usbi_err(ctx, "Device handle closed while transfer was still being processed, but the device is still connected as far as we know");
-
-			if (itransfer->flags & USBI_TRANSFER_CANCELLING)
-				usbi_warn(ctx, "A cancellation for an in-flight transfer hasn't completed but closing the device handle");
-			else
-				usbi_err(ctx, "A cancellation hasn't even been scheduled on the transfer for which the device is closing");
-		}
-
-		/* remove from the list of in-flight transfers and make sure
-		 * we don't accidentally use the device handle in the future
-		 * (or that such accesses will be easily caught and identified as a crash)
-		 */
-		usbi_mutex_lock(&itransfer->lock);
-		list_del(&itransfer->list);
-		transfer->dev_handle = NULL;
-		usbi_mutex_unlock(&itransfer->lock);
-
-		/* it is up to the user to free up the actual transfer struct.  this is
-		 * just making sure that we don't attempt to process the transfer after
-		 * the device handle is invalid
-		 */
-		usbi_dbg("Removed transfer %p from the in-flight list because device handle %p closed",
-			 transfer, dev_handle);
-	}
-	usbi_mutex_unlock(&ctx->flying_transfers_lock);
-
-	libusb_unlock_events(ctx);
-
-	usbi_mutex_lock(&ctx->open_devs_lock);
-	list_del(&dev_handle->list);
-	usbi_mutex_unlock(&ctx->open_devs_lock);
-
-	usbi_backend->close(dev_handle);
-	libusb_unref_device(dev_handle->dev);
-	usbi_mutex_destroy(&dev_handle->lock);
-	free(dev_handle);
-}
-
-/** \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
- */
-void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
-{
-	struct libusb_context *ctx;
-	unsigned char dummy = 1;
-	ssize_t r;
-
-	if (!dev_handle)
-		return;
-	usbi_dbg("");
-
-	ctx = HANDLE_CTX(dev_handle);
-
-	/* Similarly to libusb_open(), we want to interrupt all event handlers
-	 * at this point. More importantly, we want to perform the actual close of
-	 * the device while holding the event handling lock (preventing any other
-	 * thread from doing event handling) because we will be removing a file
-	 * descriptor from the polling loop. */
-
-	/* record that we are messing with poll fds */
-	usbi_mutex_lock(&ctx->pollfd_modify_lock);
-	ctx->pollfd_modify++;
-	usbi_mutex_unlock(&ctx->pollfd_modify_lock);
-
-	/* write some data on control pipe to interrupt event handlers */
-	r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
-	if (r <= 0) {
-		usbi_warn(ctx, "internal signalling write failed, closing anyway");
-		do_close(ctx, dev_handle);
-		usbi_mutex_lock(&ctx->pollfd_modify_lock);
-		ctx->pollfd_modify--;
-		usbi_mutex_unlock(&ctx->pollfd_modify_lock);
-		return;
-	}
-
-	/* take event handling lock */
-	libusb_lock_events(ctx);
-
-	/* read the dummy data */
-	r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
-	if (r <= 0)
-		usbi_warn(ctx, "internal signalling read failed, closing anyway");
-
-	/* Close the device */
-	do_close(ctx, dev_handle);
-
-	/* we're done with modifying poll fds */
-	usbi_mutex_lock(&ctx->pollfd_modify_lock);
-	ctx->pollfd_modify--;
-	usbi_mutex_unlock(&ctx->pollfd_modify_lock);
-
-	/* Release event handling lock and wake up event waiters */
-	libusb_unlock_events(ctx);
-}
-
-/** \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
- */
-DEFAULT_VISIBILITY
-libusb_device * LIBUSB_CALL 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
- */
-int API_EXPORTED 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;
-			*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
- */
-int API_EXPORTED 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
- */
-int API_EXPORTED libusb_claim_interface(libusb_device_handle *dev,
-	int interface_number)
-{
-	int r = 0;
-
-	usbi_dbg("interface %d", interface_number);
-	if (interface_number >= USB_MAXINTERFACES)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
-	usbi_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:
-	usbi_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
- */
-int API_EXPORTED libusb_release_interface(libusb_device_handle *dev,
-	int interface_number)
-{
-	int r;
-
-	usbi_dbg("interface %d", interface_number);
-	if (interface_number >= USB_MAXINTERFACES)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
-	usbi_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:
-	usbi_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
- */
-int API_EXPORTED 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 >= USB_MAXINTERFACES)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
-	usbi_mutex_lock(&dev->lock);
-	if (!(dev->claimed_interfaces & (1 << interface_number))) {
-		usbi_mutex_unlock(&dev->lock);
-		return LIBUSB_ERROR_NOT_FOUND;
-	}
-	usbi_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
- */
-int API_EXPORTED 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
- */
-int API_EXPORTED 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.
- *
- * This functionality is not available on Windows.
- *
- * \param dev a device handle
- * \param interface_number 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 LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
- * is not available
- * \returns another LIBUSB_ERROR code on other failure
- * \see libusb_detach_kernel_driver()
- */
-int API_EXPORTED libusb_kernel_driver_active(libusb_device_handle *dev,
-	int interface_number)
-{
-	usbi_dbg("interface %d", interface_number);
-	if (usbi_backend->kernel_driver_active)
-		return usbi_backend->kernel_driver_active(dev, interface_number);
-	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.
- *
- * This functionality is not available on Darwin or Windows.
- *
- * \param dev a device handle
- * \param interface_number 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 LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
- * is not available
- * \returns another LIBUSB_ERROR code on other failure
- * \see libusb_kernel_driver_active()
- */
-int API_EXPORTED libusb_detach_kernel_driver(libusb_device_handle *dev,
-	int interface_number)
-{
-	usbi_dbg("interface %d", interface_number);
-	if (usbi_backend->detach_kernel_driver)
-		return usbi_backend->detach_kernel_driver(dev, interface_number);
-	else
-		return LIBUSB_ERROR_NOT_SUPPORTED;
-}
-
-/** \ingroup dev
- * Re-attach an interface's kernel driver, which was previously detached
- * using libusb_detach_kernel_driver(). This call is only effective on
- * Linux and returns LIBUSB_ERROR_NOT_SUPPORTED on all other platforms.
- *
- * This functionality is not available on Darwin or Windows.
- *
- * \param dev a device handle
- * \param interface_number the interface to attach 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 LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
- * is not available
- * \returns LIBUSB_ERROR_BUSY if the driver cannot be attached because the
- * interface is claimed by a program or driver
- * \returns another LIBUSB_ERROR code on other failure
- * \see libusb_kernel_driver_active()
- */
-int API_EXPORTED libusb_attach_kernel_driver(libusb_device_handle *dev,
-	int interface_number)
-{
-	usbi_dbg("interface %d", interface_number);
-	if (usbi_backend->attach_kernel_driver)
-		return usbi_backend->attach_kernel_driver(dev, interface_number);
-	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 its 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
- */
-void API_EXPORTED 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.
- *
- * If you do not provide an output location for a context pointer, a default
- * context will be created. If there was already a default context, it will
- * be reused (and nothing will be initialized/reinitialized).
- *
- * \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
- * \see contexts
- */
-int API_EXPORTED libusb_init(libusb_context **context)
-{
-	char *dbg = getenv("LIBUSB_DEBUG");
-	struct libusb_context *ctx;
-	int r;
-
-	usbi_mutex_static_lock(&default_context_lock);
-	if (!context && usbi_default_context) {
-		r = 0;
-		usbi_dbg("reusing default context");
-		default_context_refcnt++;
-		usbi_mutex_static_unlock(&default_context_lock);
-		return 0;
-	}
-
-	ctx = malloc(sizeof(*ctx));
-	if (!ctx) {
-		r = LIBUSB_ERROR_NO_MEM;
-		goto err_unlock;
-	}
-	memset(ctx, 0, sizeof(*ctx));
-
-	if (dbg) {
-		ctx->debug = atoi(dbg);
-		if (ctx->debug)
-			ctx->debug_fixed = 1;
-	}
-
-	usbi_dbg("");
-
-	if (usbi_backend->init) {
-		r = usbi_backend->init(ctx);
-		if (r)
-			goto err_free_ctx;
-	}
-
-	usbi_mutex_init(&ctx->usb_devs_lock, NULL);
-	usbi_mutex_init(&ctx->open_devs_lock, NULL);
-	list_init(&ctx->usb_devs);
-	list_init(&ctx->open_devs);
-
-	r = usbi_io_init(ctx);
-	if (r < 0) {
-		if (usbi_backend->exit)
-			usbi_backend->exit();
-		goto err_destroy_mutex;
-	}
-
-	if (context) {
-		*context = ctx;
-	} else if (!usbi_default_context) {
-		usbi_dbg("created default context");
-		usbi_default_context = ctx;
-		default_context_refcnt++;
-	}
-	usbi_mutex_static_unlock(&default_context_lock);
-
-	return 0;
-
-err_destroy_mutex:
-	usbi_mutex_destroy(&ctx->open_devs_lock);
-	usbi_mutex_destroy(&ctx->usb_devs_lock);
-err_free_ctx:
-	free(ctx);
-err_unlock:
-	usbi_mutex_static_unlock(&default_context_lock);
-	return r;
-}
-
-/** \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
- */
-void API_EXPORTED libusb_exit(struct libusb_context *ctx)
-{
-	usbi_dbg("");
-	USBI_GET_CONTEXT(ctx);
-
-	/* if working with default context, only actually do the deinitialization
-	 * if we're the last user */
-	if (ctx == usbi_default_context) {
-		usbi_mutex_static_lock(&default_context_lock);
-		if (--default_context_refcnt > 0) {
-			usbi_dbg("not destroying default context");
-			usbi_mutex_static_unlock(&default_context_lock);
-			return;
-		}
-		usbi_dbg("destroying default context");
-		usbi_default_context = NULL;
-		usbi_mutex_static_unlock(&default_context_lock);
-	}
-
-	/* a little sanity check. doesn't bother with open_devs locking because
-	 * unless there is an application bug, nobody will be accessing this. */
-	if (!list_empty(&ctx->open_devs))
-		usbi_warn(ctx, "application left some devices open");
-
-	usbi_io_exit(ctx);
-	if (usbi_backend->exit)
-		usbi_backend->exit();
-
-	usbi_mutex_destroy(&ctx->open_devs_lock);
-	usbi_mutex_destroy(&ctx->usb_devs_lock);
-	free(ctx);
-}
-
-/** \ingroup misc
- * Check if the running library has a given capability.
- *
- * \param capability the \ref libusb_capability to check for
- * \returns 1 if the running library has the capability, 0 otherwise
- */
-int API_EXPORTED libusb_has_capability(uint32_t capability)
-{
-	switch (capability) {
-	case LIBUSB_CAN_GET_DEVICE_SPEED:
-		return 1;
-	default:
-		break;
-	}
-	return 0;
-}
-
-void usbi_log_v(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);
-
-	vfprintf(stream, format, args);
-
-	fprintf(stream, "\n");
-}
-
-void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
-	const char *function, const char *format, ...)
-{
-	va_list args;
-
-	va_start (args, format);
-	usbi_log_v(ctx, level, function, format, args);
-	va_end (args);
-}
-
-/** \ingroup misc
- * Returns a constant NULL-terminated string with the ASCII name of a libusb
- * error code. The caller must not free() the returned string.
- *
- * \param error_code The \ref libusb_error code to return the name of.
- * \returns The error name, or the string **UNKNOWN** if the value of
- * error_code is not a known error code.
- */
-DEFAULT_VISIBILITY const char * LIBUSB_CALL libusb_error_name(int error_code)
-{
-	enum libusb_error error = error_code;
-	switch (error) {
-	case LIBUSB_SUCCESS:
-		return "LIBUSB_SUCCESS";
-	case LIBUSB_ERROR_IO:
-		return "LIBUSB_ERROR_IO";
-	case LIBUSB_ERROR_INVALID_PARAM:
-		return "LIBUSB_ERROR_INVALID_PARAM";
-	case LIBUSB_ERROR_ACCESS:
-		return "LIBUSB_ERROR_ACCESS";
-	case LIBUSB_ERROR_NO_DEVICE:
-		return "LIBUSB_ERROR_NO_DEVICE";
-	case LIBUSB_ERROR_NOT_FOUND:
-		return "LIBUSB_ERROR_NOT_FOUND";
-	case LIBUSB_ERROR_BUSY:
-		return "LIBUSB_ERROR_BUSY";
-	case LIBUSB_ERROR_TIMEOUT:
-		return "LIBUSB_ERROR_TIMEOUT";
-	case LIBUSB_ERROR_OVERFLOW:
-		return "LIBUSB_ERROR_OVERFLOW";
-	case LIBUSB_ERROR_PIPE:
-		return "LIBUSB_ERROR_PIPE";
-	case LIBUSB_ERROR_INTERRUPTED:
-		return "LIBUSB_ERROR_INTERRUPTED";
-	case LIBUSB_ERROR_NO_MEM:
-		return "LIBUSB_ERROR_NO_MEM";
-	case LIBUSB_ERROR_NOT_SUPPORTED:
-		return "LIBUSB_ERROR_NOT_SUPPORTED";
-	case LIBUSB_ERROR_OTHER:
-		return "LIBUSB_ERROR_OTHER";
-	}
-	return "**UNKNOWN**";
-}