Revert 129069 - Import libusb 1.0.9-rc3 into third_party.

third_party/libusb/libusb/libusbi.h

Index: third_party/libusb/libusb/libusbi.h
===================================================================
--- third_party/libusb/libusb/libusbi.h	(revision 129100)
+++ third_party/libusb/libusb/libusbi.h	(working copy)
@@ -1,889 +0,0 @@
-/*
- * Internal header for libusb
- * Copyright (C) 2007-2009 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
- */
-
-#ifndef LIBUSBI_H
-#define LIBUSBI_H
-
-#include <config.h>
-
-#include <stddef.h>
-#include <stdint.h>
-#include <time.h>
-#ifdef HAVE_POLL_H
-#include <poll.h>
-#endif
-
-#include <libusb.h>
-
-/* Inside the libusb code, mark all public functions as follows:
- *   return_type API_EXPORTED function_name(params) { ... }
- * But if the function returns a pointer, mark it as follows:
- *   DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
- * In the libusb public header, mark all declarations as:
- *   return_type LIBUSB_CALL function_name(params);
- */
-#define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
-
-#define DEVICE_DESC_LENGTH		18
-
-#define USB_MAXENDPOINTS	32
-#define USB_MAXINTERFACES	32
-#define USB_MAXCONFIG		8
-
-struct list_head {
-	struct list_head *prev, *next;
-};
-
-/* Get an entry from the list
- * 	ptr - the address of this list_head element in "type"
- * 	type - the data type that contains "member"
- * 	member - the list_head element in "type"
- */
-#define list_entry(ptr, type, member) \
-	((type *)((uintptr_t)(ptr) - (uintptr_t)(&((type *)0L)->member)))
-
-/* Get each entry from a list
- *	pos - A structure pointer has a "member" element
- *	head - list head
- *	member - the list_head element in "pos"
- *	type - the type of the first parameter
- */
-#define list_for_each_entry(pos, head, member, type)			\
-	for (pos = list_entry((head)->next, type, member);			\
-		 &pos->member != (head);								\
-		 pos = list_entry(pos->member.next, type, member))
-
-#define list_for_each_entry_safe(pos, n, head, member, type)	\
-	for (pos = list_entry((head)->next, type, member),			\
-		 n = list_entry(pos->member.next, type, member);		\
-		 &pos->member != (head);								\
-		 pos = n, n = list_entry(n->member.next, type, member))
-
-#define list_empty(entry) ((entry)->next == (entry))
-
-static inline void list_init(struct list_head *entry)
-{
-	entry->prev = entry->next = entry;
-}
-
-static inline void list_add(struct list_head *entry, struct list_head *head)
-{
-	entry->next = head->next;
-	entry->prev = head;
-
-	head->next->prev = entry;
-	head->next = entry;
-}
-
-static inline void list_add_tail(struct list_head *entry,
-	struct list_head *head)
-{
-	entry->next = head;
-	entry->prev = head->prev;
-
-	head->prev->next = entry;
-	head->prev = entry;
-}
-
-static inline void list_del(struct list_head *entry)
-{
-	entry->next->prev = entry->prev;
-	entry->prev->next = entry->next;
-}
-
-#define container_of(ptr, type, member) ({                      \
-        const typeof( ((type *)0)->member ) *mptr = (ptr);    \
-        (type *)( (char *)mptr - offsetof(type,member) );})
-
-#define MIN(a, b)	((a) < (b) ? (a) : (b))
-#define MAX(a, b)	((a) > (b) ? (a) : (b))
-
-#define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
-
-enum usbi_log_level {
-	LOG_LEVEL_DEBUG,
-	LOG_LEVEL_INFO,
-	LOG_LEVEL_WARNING,
-	LOG_LEVEL_ERROR,
-};
-
-void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
-	const char *function, const char *format, ...);
-
-#if !defined(_MSC_VER) || _MSC_VER > 1200
-
-#ifdef ENABLE_LOGGING
-#define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
-#else
-#define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
-#endif
-
-#ifdef ENABLE_DEBUG_LOGGING
-#define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
-#else
-#define usbi_dbg(...) do {} while(0)
-#endif
-
-#define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
-#define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
-#define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
-
-#else /* !defined(_MSC_VER) || _MSC_VER > 1200 */
-
-void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
-	const char *function, const char *format, va_list args);
-
-#ifdef ENABLE_LOGGING
-#define LOG_BODY(ctxt, level) \
-{                             \
-	va_list args;             \
-	va_start (args, format);  \
-	usbi_log_v(ctxt, level, "", format, args); \
-	va_end(args);             \
-}
-#else
-#define LOG_BODY(ctxt, level) do { (void)(ctxt); } while(0)
-#endif
-
-static inline void usbi_info(struct libusb_context *ctx, const char *format,
-	...)
-	LOG_BODY(ctx,LOG_LEVEL_INFO)
-static inline void usbi_warn(struct libusb_context *ctx, const char *format,
-	...)
-	LOG_BODY(ctx,LOG_LEVEL_WARNING)
-static inline void usbi_err( struct libusb_context *ctx, const char *format,
-	...)
-	LOG_BODY(ctx,LOG_LEVEL_ERROR)
-
-static inline void usbi_dbg(const char *format, ...)
-#ifdef ENABLE_DEBUG_LOGGING
-	LOG_BODY(NULL,LOG_LEVEL_DEBUG)
-#else
-{ }
-#endif
-
-#endif /* !defined(_MSC_VER) || _MSC_VER > 1200 */
-
-#define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
-#define DEVICE_CTX(dev) ((dev)->ctx)
-#define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
-#define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
-#define ITRANSFER_CTX(transfer) \
-	(TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
-
-/* Internal abstractions for thread synchronization and poll */
-#if defined(THREADS_POSIX)
-#include <os/threads_posix.h>
-#elif defined(OS_WINDOWS)
-#include <os/threads_windows.h>
-#endif
-
-#if defined(OS_LINUX) || defined(OS_DARWIN)
-#include <unistd.h>
-#include <os/poll_posix.h>
-#elif defined(OS_WINDOWS)
-#include <os/poll_windows.h>
-#endif
-
-extern struct libusb_context *usbi_default_context;
-
-struct libusb_context {
-	int debug;
-	int debug_fixed;
-
-	/* internal control pipe, used for interrupting event handling when
-	 * something needs to modify poll fds. */
-	int ctrl_pipe[2];
-
-	struct list_head usb_devs;
-	usbi_mutex_t usb_devs_lock;
-
-	/* A list of open handles. Backends are free to traverse this if required.
-	 */
-	struct list_head open_devs;
-	usbi_mutex_t open_devs_lock;
-
-	/* this is a list of in-flight transfer handles, sorted by timeout
-	 * expiration. URBs to timeout the soonest are placed at the beginning of
-	 * the list, URBs that will time out later are placed after, and urbs with
-	 * infinite timeout are always placed at the very end. */
-	struct list_head flying_transfers;
-	usbi_mutex_t flying_transfers_lock;
-
-	/* list of poll fds */
-	struct list_head pollfds;
-	usbi_mutex_t pollfds_lock;
-
-	/* a counter that is set when we want to interrupt event handling, in order
-	 * to modify the poll fd set. and a lock to protect it. */
-	unsigned int pollfd_modify;
-	usbi_mutex_t pollfd_modify_lock;
-
-	/* user callbacks for pollfd changes */
-	libusb_pollfd_added_cb fd_added_cb;
-	libusb_pollfd_removed_cb fd_removed_cb;
-	void *fd_cb_user_data;
-
-	/* ensures that only one thread is handling events at any one time */
-	usbi_mutex_t events_lock;
-
-	/* used to see if there is an active thread doing event handling */
-	int event_handler_active;
-
-	/* used to wait for event completion in threads other than the one that is
-	 * event handling */
-	usbi_mutex_t event_waiters_lock;
-	usbi_cond_t event_waiters_cond;
-
-#ifdef USBI_TIMERFD_AVAILABLE
-	/* used for timeout handling, if supported by OS.
-	 * this timerfd is maintained to trigger on the next pending timeout */
-	int timerfd;
-#endif
-};
-
-#ifdef USBI_TIMERFD_AVAILABLE
-#define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
-#else
-#define usbi_using_timerfd(ctx) (0)
-#endif
-
-struct libusb_device {
-	/* lock protects refcnt, everything else is finalized at initialization
-	 * time */
-	usbi_mutex_t lock;
-	int refcnt;
-
-	struct libusb_context *ctx;
-
-	uint8_t bus_number;
-	uint8_t device_address;
-	uint8_t num_configurations;
-	enum libusb_speed speed;
-
-	struct list_head list;
-	unsigned long session_data;
-	unsigned char os_priv[0];
-};
-
-struct libusb_device_handle {
-	/* lock protects claimed_interfaces */
-	usbi_mutex_t lock;
-	unsigned long claimed_interfaces;
-
-	struct list_head list;
-	struct libusb_device *dev;
-	unsigned char os_priv[0];
-};
-
-enum {
-  USBI_CLOCK_MONOTONIC,
-  USBI_CLOCK_REALTIME
-};
-
-/* in-memory transfer layout:
- *
- * 1. struct usbi_transfer
- * 2. struct libusb_transfer (which includes iso packets) [variable size]
- * 3. os private data [variable size]
- *
- * from a libusb_transfer, you can get the usbi_transfer by rewinding the
- * appropriate number of bytes.
- * the usbi_transfer includes the number of allocated packets, so you can
- * determine the size of the transfer and hence the start and length of the
- * OS-private data.
- */
-
-struct usbi_transfer {
-	int num_iso_packets;
-	struct list_head list;
-	struct timeval timeout;
-	int transferred;
-	uint8_t flags;
-
-	/* this lock is held during libusb_submit_transfer() and
-	 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
-	 * cancellation, submission-during-cancellation, etc). the OS backend
-	 * should also take this lock in the handle_events path, to prevent the user
-	 * cancelling the transfer from another thread while you are processing
-	 * its completion (presumably there would be races within your OS backend
-	 * if this were possible). */
-	usbi_mutex_t lock;
-};
-
-enum usbi_transfer_flags {
-	/* The transfer has timed out */
-	USBI_TRANSFER_TIMED_OUT = 1 << 0,
-
-	/* Set by backend submit_transfer() if the OS handles timeout */
-	USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
-
-	/* Cancellation was requested via libusb_cancel_transfer() */
-	USBI_TRANSFER_CANCELLING = 1 << 2,
-
-	/* Operation on the transfer failed because the device disappeared */
-	USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
-};
-
-#define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
-	((struct libusb_transfer *)(((unsigned char *)(transfer)) \
-		+ sizeof(struct usbi_transfer)))
-#define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
-	((struct usbi_transfer *)(((unsigned char *)(transfer)) \
-		- sizeof(struct usbi_transfer)))
-
-static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
-{
-	return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
-		+ sizeof(struct libusb_transfer)
-		+ (transfer->num_iso_packets
-			* sizeof(struct libusb_iso_packet_descriptor));
-}
-
-/* bus structures */
-
-/* All standard descriptors have these 2 fields in common */
-struct usb_descriptor_header {
-	uint8_t  bLength;
-	uint8_t  bDescriptorType;
-};
-
-/* shared data and functions */
-
-int usbi_io_init(struct libusb_context *ctx);
-void usbi_io_exit(struct libusb_context *ctx);
-
-struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
-	unsigned long session_id);
-struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
-	unsigned long session_id);
-int usbi_sanitize_device(struct libusb_device *dev);
-void usbi_handle_disconnect(struct libusb_device_handle *handle);
-
-int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
-	enum libusb_transfer_status status);
-int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
-
-int usbi_parse_descriptor(unsigned char *source, const char *descriptor,
-	void *dest, int host_endian);
-int usbi_get_config_index_by_value(struct libusb_device *dev,
-	uint8_t bConfigurationValue, int *idx);
-
-/* polling */
-
-struct usbi_pollfd {
-	/* must come first */
-	struct libusb_pollfd pollfd;
-
-	struct list_head list;
-};
-
-int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
-void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
-void usbi_fd_notification(struct libusb_context *ctx);
-
-/* device discovery */
-
-/* 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. */
-struct discovered_devs {
-	size_t len;
-	size_t capacity;
-	struct libusb_device *devices[0];
-};
-
-struct discovered_devs *discovered_devs_append(
-	struct discovered_devs *discdevs, struct libusb_device *dev);
-
-/* OS abstraction */
-
-/* This is the interface that OS backends need to implement.
- * All fields are mandatory, except ones explicitly noted as optional. */
-struct usbi_os_backend {
-	/* A human-readable name for your backend, e.g. "Linux usbfs" */
-	const char *name;
-
-	/* Perform initialization of your backend. You might use this function
-	 * to determine specific capabilities of the system, allocate required
-	 * data structures for later, etc.
-	 *
-	 * This function is called when a libusb user initializes the library
-	 * prior to use.
-	 *
-	 * Return 0 on success, or a LIBUSB_ERROR code on failure.
-	 */
-	int (*init)(struct libusb_context *ctx);
-
-	/* Deinitialization. Optional. This function should destroy anything
-	 * that was set up by init.
-	 *
-	 * This function is called when the user deinitializes the library.
-	 */
-	void (*exit)(void);
-
-	/* Enumerate all the USB devices on the system, returning them in a list
-	 * of discovered devices.
-	 *
-	 * Your implementation should enumerate all devices on the system,
-	 * regardless of whether they have been seen before or not.
-	 *
-	 * When you have found a device, compute a session ID for it. The session
-	 * ID should uniquely represent that particular device for that particular
-	 * connection session since boot (i.e. if you disconnect and reconnect a
-	 * device immediately after, it should be assigned a different session ID).
-	 * If your OS cannot provide a unique session ID as described above,
-	 * presenting a session ID of (bus_number << 8 | device_address) should
-	 * be sufficient. Bus numbers and device addresses wrap and get reused,
-	 * but that is an unlikely case.
-	 *
-	 * After computing a session ID for a device, call
-	 * usbi_get_device_by_session_id(). This function checks if libusb already
-	 * knows about the device, and if so, it provides you with a libusb_device
-	 * structure for it.
-	 *
-	 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
-	 * a new device structure for the device. Call usbi_alloc_device() to
-	 * obtain a new libusb_device structure with reference count 1. Populate
-	 * the bus_number and device_address attributes of the new device, and
-	 * perform any other internal backend initialization you need to do. At
-	 * this point, you should be ready to provide device descriptors and so
-	 * on through the get_*_descriptor functions. Finally, call
-	 * usbi_sanitize_device() to perform some final sanity checks on the
-	 * device. Assuming all of the above succeeded, we can now continue.
-	 * If any of the above failed, remember to unreference the device that
-	 * was returned by usbi_alloc_device().
-	 *
-	 * At this stage we have a populated libusb_device structure (either one
-	 * that was found earlier, or one that we have just allocated and
-	 * populated). This can now be added to the discovered devices list
-	 * using discovered_devs_append(). Note that discovered_devs_append()
-	 * may reallocate the list, returning a new location for it, and also
-	 * note that reallocation can fail. Your backend should handle these
-	 * error conditions appropriately.
-	 *
-	 * This function should not generate any bus I/O and should not block.
-	 * If I/O is required (e.g. reading the active configuration value), it is
-	 * OK to ignore these suggestions :)
-	 *
-	 * This function is executed when the user wishes to retrieve a list
-	 * of USB devices connected to the system.
-	 *
-	 * Return 0 on success, or a LIBUSB_ERROR code on failure.
-	 */
-	int (*get_device_list)(struct libusb_context *ctx,
-		struct discovered_devs **discdevs);
-
-	/* Open a device for I/O and other USB operations. The device handle
-	 * is preallocated for you, you can retrieve the device in question
-	 * through handle->dev.
-	 *
-	 * Your backend should allocate any internal resources required for I/O
-	 * and other operations so that those operations can happen (hopefully)
-	 * without hiccup. This is also a good place to inform libusb that it
-	 * should monitor certain file descriptors related to this device -
-	 * see the usbi_add_pollfd() function.
-	 *
-	 * This function should not generate any bus I/O and should not block.
-	 *
-	 * This function is called when the user attempts to obtain a device
-	 * handle for a device.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
-	 *   discovery
-	 * - another LIBUSB_ERROR code on other failure
-	 *
-	 * Do not worry about freeing the handle on failed open, the upper layers
-	 * do this for you.
-	 */
-	int (*open)(struct libusb_device_handle *handle);
-
-	/* Close a device such that the handle cannot be used again. Your backend
-	 * should destroy any resources that were allocated in the open path.
-	 * This may also be a good place to call usbi_remove_pollfd() to inform
-	 * libusb of any file descriptors associated with this device that should
-	 * no longer be monitored.
-	 *
-	 * This function is called when the user closes a device handle.
-	 */
-	void (*close)(struct libusb_device_handle *handle);
-
-	/* Retrieve the device descriptor from a device.
-	 *
-	 * The descriptor should be retrieved from memory, NOT via bus I/O to the
-	 * device. This means that you may have to cache it in a private structure
-	 * during get_device_list enumeration. Alternatively, you may be able
-	 * to retrieve it from a kernel interface (some Linux setups can do this)
-	 * still without generating bus I/O.
-	 *
-	 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
-	 * buffer, which is guaranteed to be big enough.
-	 *
-	 * This function is called when sanity-checking a device before adding
-	 * it to the list of discovered devices, and also when the user requests
-	 * to read the device descriptor.
-	 *
-	 * This function is expected to return the descriptor in bus-endian format
-	 * (LE). If it returns the multi-byte values in host-endian format,
-	 * set the host_endian output parameter to "1".
-	 *
-	 * Return 0 on success or a LIBUSB_ERROR code on failure.
-	 */
-	int (*get_device_descriptor)(struct libusb_device *device,
-		unsigned char *buffer, int *host_endian);
-
-	/* Get the ACTIVE configuration descriptor for a device.
-	 *
-	 * The descriptor should be retrieved from memory, NOT via bus I/O to the
-	 * device. This means that you may have to cache it in a private structure
-	 * during get_device_list enumeration. You may also have to keep track
-	 * of which configuration is active when the user changes it.
-	 *
-	 * This function is expected to write len bytes of data into buffer, which
-	 * is guaranteed to be big enough. If you can only do a partial write,
-	 * return an error code.
-	 *
-	 * This function is expected to return the descriptor in bus-endian format
-	 * (LE). If it returns the multi-byte values in host-endian format,
-	 * set the host_endian output parameter to "1".
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*get_active_config_descriptor)(struct libusb_device *device,
-		unsigned char *buffer, size_t len, int *host_endian);
-
-	/* Get a specific configuration descriptor for a device.
-	 *
-	 * The descriptor should be retrieved from memory, NOT via bus I/O to the
-	 * device. This means that you may have to cache it in a private structure
-	 * during get_device_list enumeration.
-	 *
-	 * The requested descriptor is expressed as a zero-based index (i.e. 0
-	 * indicates that we are requesting the first descriptor). The index does
-	 * not (necessarily) equal the bConfigurationValue of the configuration
-	 * being requested.
-	 *
-	 * This function is expected to write len bytes of data into buffer, which
-	 * is guaranteed to be big enough. If you can only do a partial write,
-	 * return an error code.
-	 *
-	 * This function is expected to return the descriptor in bus-endian format
-	 * (LE). If it returns the multi-byte values in host-endian format,
-	 * set the host_endian output parameter to "1".
-	 *
-	 * Return 0 on success or a LIBUSB_ERROR code on failure.
-	 */
-	int (*get_config_descriptor)(struct libusb_device *device,
-		uint8_t config_index, unsigned char *buffer, size_t len,
-		int *host_endian);
-
-	/* Get the bConfigurationValue for the active configuration for a device.
-	 * Optional. This should only be implemented if you can retrieve it from
-	 * cache (don't generate I/O).
-	 *
-	 * If you cannot retrieve this from cache, either do not implement this
-	 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
-	 * libusb to retrieve the information through a standard control transfer.
-	 *
-	 * This function must be non-blocking.
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
-	 *   blocking
-	 * - another LIBUSB_ERROR code on other failure.
-	 */
-	int (*get_configuration)(struct libusb_device_handle *handle, int *config);
-
-	/* Set the active configuration for a device.
-	 *
-	 * A configuration value of -1 should put the device in unconfigured state.
-	 *
-	 * This function can block.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
-	 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
-	 *   configuration cannot be changed)
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - another LIBUSB_ERROR code on other failure.
-	 */
-	int (*set_configuration)(struct libusb_device_handle *handle, int config);
-
-	/* Claim an interface. When claimed, the application can then perform
-	 * I/O to an interface's endpoints.
-	 *
-	 * This function should not generate any bus I/O and should not block.
-	 * Interface claiming is a logical operation that simply ensures that
-	 * no other drivers/applications are using the interface, and after
-	 * claiming, no other drivers/applicatiosn can use the interface because
-	 * we now "own" it.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
-	 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
-
-	/* Release a previously claimed interface.
-	 *
-	 * This function should also generate a SET_INTERFACE control request,
-	 * resetting the alternate setting of that interface to 0. It's OK for
-	 * this function to block as a result.
-	 *
-	 * You will only ever be asked to release an interface which was
-	 * successfully claimed earlier.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
-
-	/* Set the alternate setting for an interface.
-	 *
-	 * You will only ever be asked to set the alternate setting for an
-	 * interface which was successfully claimed earlier.
-	 *
-	 * It's OK for this function to block.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*set_interface_altsetting)(struct libusb_device_handle *handle,
-		int interface_number, int altsetting);
-
-	/* Clear a halt/stall condition on an endpoint.
-	 *
-	 * It's OK for this function to block.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*clear_halt)(struct libusb_device_handle *handle,
-		unsigned char endpoint);
-
-	/* Perform a USB port reset to reinitialize a device.
-	 *
-	 * If possible, the handle should still be usable after the reset
-	 * completes, assuming that the device descriptors did not change during
-	 * reset and all previous interface state can be restored.
-	 *
-	 * If something changes, or you cannot easily locate/verify the resetted
-	 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
-	 * to close the old handle and re-enumerate the device.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
-	 *   has been disconnected since it was opened
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*reset_device)(struct libusb_device_handle *handle);
-
-	/* Determine if a kernel driver is active on an interface. Optional.
-	 *
-	 * The presence of a kernel driver on an interface indicates that any
-	 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
-	 *
-	 * Return:
-	 * - 0 if no driver is active
-	 * - 1 if a driver is active
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*kernel_driver_active)(struct libusb_device_handle *handle,
-		int interface_number);
-
-	/* Detach a kernel driver from an interface. Optional.
-	 *
-	 * After detaching a kernel driver, the interface should be available
-	 * for claim.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
-	 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*detach_kernel_driver)(struct libusb_device_handle *handle,
-		int interface_number);
-
-	/* Attach a kernel driver to an interface. Optional.
-	 *
-	 * Reattach a kernel driver to the device.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
-	 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
-	 *   was opened
-	 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
-	 *   preventing reattachment
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*attach_kernel_driver)(struct libusb_device_handle *handle,
-		int interface_number);
-
-	/* Destroy a device. Optional.
-	 *
-	 * This function is called when the last reference to a device is
-	 * destroyed. It should free any resources allocated in the get_device_list
-	 * path.
-	 */
-	void (*destroy_device)(struct libusb_device *dev);
-
-	/* Submit a transfer. Your implementation should take the transfer,
-	 * morph it into whatever form your platform requires, and submit it
-	 * asynchronously.
-	 *
-	 * This function must not block.
-	 *
-	 * Return:
-	 * - 0 on success
-	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
-	 * - another LIBUSB_ERROR code on other failure
-	 */
-	int (*submit_transfer)(struct usbi_transfer *itransfer);
-
-	/* Cancel a previously submitted transfer.
-	 *
-	 * This function must not block. The transfer cancellation must complete
-	 * later, resulting in a call to usbi_handle_transfer_cancellation()
-	 * from the context of handle_events.
-	 */
-	int (*cancel_transfer)(struct usbi_transfer *itransfer);
-
-	/* Clear a transfer as if it has completed or cancelled, but do not
-	 * report any completion/cancellation to the library. You should free
-	 * all private data from the transfer as if you were just about to report
-	 * completion or cancellation.
-	 *
-	 * This function might seem a bit out of place. It is used when libusb
-	 * detects a disconnected device - it calls this function for all pending
-	 * transfers before reporting completion (with the disconnect code) to
-	 * the user. Maybe we can improve upon this internal interface in future.
-	 */
-	void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
-
-	/* Handle any pending events. This involves monitoring any active
-	 * transfers and processing their completion or cancellation.
-	 *
-	 * The function is passed an array of pollfd structures (size nfds)
-	 * as a result of the poll() system call. The num_ready parameter
-	 * indicates the number of file descriptors that have reported events
-	 * (i.e. the poll() return value). This should be enough information
-	 * for you to determine which actions need to be taken on the currently
-	 * active transfers.
-	 *
-	 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
-	 * For completed transfers, call usbi_handle_transfer_completion().
-	 * For control/bulk/interrupt transfers, populate the "transferred"
-	 * element of the appropriate usbi_transfer structure before calling the
-	 * above functions. For isochronous transfers, populate the status and
-	 * transferred fields of the iso packet descriptors of the transfer.
-	 *
-	 * This function should also be able to detect disconnection of the
-	 * device, reporting that situation with usbi_handle_disconnect().
-	 *
-	 * When processing an event related to a transfer, you probably want to
-	 * take usbi_transfer.lock to prevent races. See the documentation for
-	 * the usbi_transfer structure.
-	 *
-	 * Return 0 on success, or a LIBUSB_ERROR code on failure.
-	 */
-	int (*handle_events)(struct libusb_context *ctx,
-		struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
-
-	/* Get time from specified clock. At least two clocks must be implemented
-	   by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
-
-	   Description of clocks:
-	     USBI_CLOCK_REALTIME : clock returns time since system epoch.
-	     USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
-	                             time (usually boot).
-	 */
-	int (*clock_gettime)(int clkid, struct timespec *tp);
-
-#ifdef USBI_TIMERFD_AVAILABLE
-	/* clock ID of the clock that should be used for timerfd */
-	clockid_t (*get_timerfd_clockid)(void);
-#endif
-
-	/* Number of bytes to reserve for per-device private backend data.
-	 * This private data area is accessible through the "os_priv" field of
-	 * struct libusb_device. */
-	size_t device_priv_size;
-
-	/* Number of bytes to reserve for per-handle private backend data.
-	 * This private data area is accessible through the "os_priv" field of
-	 * struct libusb_device. */
-	size_t device_handle_priv_size;
-
-	/* Number of bytes to reserve for per-transfer private backend data.
-	 * This private data area is accessible by calling
-	 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
-	 */
-	size_t transfer_priv_size;
-
-	/* Mumber of additional bytes for os_priv for each iso packet.
-	 * Can your backend use this? */
-	/* FIXME: linux can't use this any more. if other OS's cannot either,
-	 * then remove this */
-	size_t add_iso_packet_size;
-};
-
-extern const struct usbi_os_backend * const usbi_backend;
-
-extern const struct usbi_os_backend linux_usbfs_backend;
-extern const struct usbi_os_backend darwin_backend;
-extern const struct usbi_os_backend windows_backend;
-
-#endif
-