Remove obsolete "in-tree" copy of libusb-1.0

1 files changed, 0 insertions, 872 deletions

diff --git a/include/libusb-1.0/os/libusbi.h b/include/libusb-1.0/os/libusbi.h
deleted file mode 100644
index 9b2fa70..0000000
--- a/include/libusb-1.0/os/libusbi.h
+++ /dev/null
@@ -1,872 +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>
-
-#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, ...)
-#endif
-
-#ifdef ENABLE_DEBUG_LOGGING
-#define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
-#else
-#define usbi_dbg(...)
-#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) { }
-#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 <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;
-
-        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];
-};
-
-#define USBI_TRANSFER_TIMED_OUT                         (1<<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;
-};
-
-#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, 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, nfds_t 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
-