2 * Internal header for libusb
3 * Copyright © 2007-2009 Daniel Drake <dsd@gentoo.org>
4 * Copyright © 2001 Johannes Erdfelt <johannes@erdfelt.com>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
42 /* Inside the libusb code, mark all public functions as follows:
43 * return_type API_EXPORTED function_name(params) { ... }
44 * But if the function returns a pointer, mark it as follows:
45 * DEFAULT_VISIBILITY return_type * LIBUSB_CALL function_name(params) { ... }
46 * In the libusb public header, mark all declarations as:
47 * return_type LIBUSB_CALL function_name(params);
49 #define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
55 #define DEVICE_DESC_LENGTH 18
57 #define USB_MAXENDPOINTS 32
58 #define USB_MAXINTERFACES 32
59 #define USB_MAXCONFIG 8
61 /* Backend specific capabilities */
62 #define USBI_CAP_HAS_HID_ACCESS 0x00010000
63 #define USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER 0x00020000
65 /* Maximum number of bytes in a log line */
66 #define USBI_MAX_LOG_LEN 1024
67 /* Terminator for log lines */
68 #define USBI_LOG_LINE_END "\n"
70 /* The following is used to silence warnings for unused variables */
71 #define UNUSED(var) do { (void)(var); } while(0)
73 #if !defined(ARRAYSIZE)
74 #define ARRAYSIZE(array) (sizeof(array) / sizeof(array[0]))
78 struct list_head *prev, *next;
81 /* Get an entry from the list
82 * ptr - the address of this list_head element in "type"
83 * type - the data type that contains "member"
84 * member - the list_head element in "type"
86 #define list_entry(ptr, type, member) \
87 ((type *)((uintptr_t)(ptr) - (uintptr_t)offsetof(type, member)))
89 #define list_first_entry(ptr, type, member) \
90 list_entry((ptr)->next, type, member)
92 /* Get each entry from a list
93 * pos - A structure pointer has a "member" element
95 * member - the list_head element in "pos"
96 * type - the type of the first parameter
98 #define list_for_each_entry(pos, head, member, type) \
99 for (pos = list_entry((head)->next, type, member); \
100 &pos->member != (head); \
101 pos = list_entry(pos->member.next, type, member))
103 #define list_for_each_entry_safe(pos, n, head, member, type) \
104 for (pos = list_entry((head)->next, type, member), \
105 n = list_entry(pos->member.next, type, member); \
106 &pos->member != (head); \
107 pos = n, n = list_entry(n->member.next, type, member))
109 #define list_empty(entry) ((entry)->next == (entry))
111 static inline void list_init(struct list_head *entry)
113 entry->prev = entry->next = entry;
116 static inline void list_add(struct list_head *entry, struct list_head *head)
118 entry->next = head->next;
121 head->next->prev = entry;
125 static inline void list_add_tail(struct list_head *entry,
126 struct list_head *head)
129 entry->prev = head->prev;
131 head->prev->next = entry;
135 static inline void list_del(struct list_head *entry)
137 entry->next->prev = entry->prev;
138 entry->prev->next = entry->next;
139 entry->next = entry->prev = NULL;
142 static inline void *usbi_reallocf(void *ptr, size_t size)
144 void *ret = realloc(ptr, size);
150 #define container_of(ptr, type, member) ({ \
151 const typeof( ((type *)0)->member ) *mptr = (ptr); \
152 (type *)( (char *)mptr - offsetof(type,member) );})
155 #define MIN(a, b) ((a) < (b) ? (a) : (b))
158 #define MAX(a, b) ((a) > (b) ? (a) : (b))
161 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
163 #if defined(_WIN32) || defined(__CYGWIN__) || defined(_WIN32_WCE)
164 #define TIMEVAL_TV_SEC_TYPE long
166 #define TIMEVAL_TV_SEC_TYPE time_t
169 /* Some platforms don't have this define */
170 #ifndef TIMESPEC_TO_TIMEVAL
171 #define TIMESPEC_TO_TIMEVAL(tv, ts) \
173 (tv)->tv_sec = (TIMEVAL_TV_SEC_TYPE) (ts)->tv_sec; \
174 (tv)->tv_usec = (ts)->tv_nsec / 1000; \
178 void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
179 const char *function, const char *format, ...);
181 void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
182 const char *function, const char *format, va_list args);
184 #if !defined(_MSC_VER) || _MSC_VER >= 1400
186 #ifdef ENABLE_LOGGING
187 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
188 #define usbi_dbg(...) _usbi_log(NULL, LIBUSB_LOG_LEVEL_DEBUG, __VA_ARGS__)
190 #define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
191 #define usbi_dbg(...) do {} while(0)
194 #define usbi_info(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_INFO, __VA_ARGS__)
195 #define usbi_warn(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_WARNING, __VA_ARGS__)
196 #define usbi_err(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_ERROR, __VA_ARGS__)
198 #else /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
200 #ifdef ENABLE_LOGGING
201 #define LOG_BODY(ctxt, level) \
204 va_start(args, format); \
205 usbi_log_v(ctxt, level, "", format, args); \
209 #define LOG_BODY(ctxt, level) \
215 static inline void usbi_info(struct libusb_context *ctx, const char *format, ...)
216 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_INFO)
217 static inline void usbi_warn(struct libusb_context *ctx, const char *format, ...)
218 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_WARNING)
219 static inline void usbi_err(struct libusb_context *ctx, const char *format, ...)
220 LOG_BODY(ctx, LIBUSB_LOG_LEVEL_ERROR)
222 static inline void usbi_dbg(const char *format, ...)
223 LOG_BODY(NULL, LIBUSB_LOG_LEVEL_DEBUG)
225 #endif /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
227 #define USBI_GET_CONTEXT(ctx) \
230 (ctx) = usbi_default_context; \
233 #define DEVICE_CTX(dev) ((dev)->ctx)
234 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
235 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
236 #define ITRANSFER_CTX(transfer) \
237 (TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
239 #define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
240 #define IS_EPOUT(ep) (!IS_EPIN(ep))
241 #define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
242 #define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
244 /* Internal abstraction for thread synchronization */
245 #if defined(THREADS_POSIX)
246 #include "os/threads_posix.h"
247 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
248 #include "os/threads_windows.h"
251 extern struct libusb_context *usbi_default_context;
253 /* Forward declaration for use in context (fully defined inside poll abstraction) */
256 struct libusb_context {
260 /* internal event pipe, used for signalling occurrence of an internal event. */
263 struct list_head usb_devs;
264 usbi_mutex_t usb_devs_lock;
266 /* A list of open handles. Backends are free to traverse this if required.
268 struct list_head open_devs;
269 usbi_mutex_t open_devs_lock;
271 /* A list of registered hotplug callbacks */
272 struct list_head hotplug_cbs;
273 usbi_mutex_t hotplug_cbs_lock;
275 /* this is a list of in-flight transfer handles, sorted by timeout
276 * expiration. URBs to timeout the soonest are placed at the beginning of
277 * the list, URBs that will time out later are placed after, and urbs with
278 * infinite timeout are always placed at the very end. */
279 struct list_head flying_transfers;
280 /* Note paths taking both this and usbi_transfer->lock must always
281 * take this lock first */
282 usbi_mutex_t flying_transfers_lock;
284 /* user callbacks for pollfd changes */
285 libusb_pollfd_added_cb fd_added_cb;
286 libusb_pollfd_removed_cb fd_removed_cb;
287 void *fd_cb_user_data;
289 /* ensures that only one thread is handling events at any one time */
290 usbi_mutex_t events_lock;
292 /* used to see if there is an active thread doing event handling */
293 int event_handler_active;
295 /* A thread-local storage key to track which thread is performing event
297 usbi_tls_key_t event_handling_key;
299 /* used to wait for event completion in threads other than the one that is
301 usbi_mutex_t event_waiters_lock;
302 usbi_cond_t event_waiters_cond;
304 /* A lock to protect internal context event data. */
305 usbi_mutex_t event_data_lock;
307 /* A bitmask of flags that are set to indicate specific events that need to
308 * be handled. Protected by event_data_lock. */
309 unsigned int event_flags;
311 /* A counter that is set when we want to interrupt and prevent event handling,
312 * in order to safely close a device. Protected by event_data_lock. */
313 unsigned int device_close;
315 /* list and count of poll fds and an array of poll fd structures that is
316 * (re)allocated as necessary prior to polling. Protected by event_data_lock. */
317 struct list_head ipollfds;
318 struct pollfd *pollfds;
319 POLL_NFDS_TYPE pollfds_cnt;
321 /* A list of pending hotplug messages. Protected by event_data_lock. */
322 struct list_head hotplug_msgs;
324 /* A list of pending completed transfers. Protected by event_data_lock. */
325 struct list_head completed_transfers;
327 #ifdef USBI_TIMERFD_AVAILABLE
328 /* used for timeout handling, if supported by OS.
329 * this timerfd is maintained to trigger on the next pending timeout */
333 struct list_head list;
336 enum usbi_event_flags {
337 /* The list of pollfds has been modified */
338 USBI_EVENT_POLLFDS_MODIFIED = 1 << 0,
340 /* The user has interrupted the event handler */
341 USBI_EVENT_USER_INTERRUPT = 1 << 1,
344 /* Macros for managing event handling state */
345 #define usbi_handling_events(ctx) \
346 (usbi_tls_key_get((ctx)->event_handling_key) != NULL)
348 #define usbi_start_event_handling(ctx) \
349 usbi_tls_key_set((ctx)->event_handling_key, ctx)
351 #define usbi_end_event_handling(ctx) \
352 usbi_tls_key_set((ctx)->event_handling_key, NULL)
354 /* Update the following macro if new event sources are added */
355 #define usbi_pending_events(ctx) \
356 ((ctx)->event_flags || (ctx)->device_close \
357 || !list_empty(&(ctx)->hotplug_msgs) || !list_empty(&(ctx)->completed_transfers))
359 #ifdef USBI_TIMERFD_AVAILABLE
360 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
362 #define usbi_using_timerfd(ctx) (0)
365 struct libusb_device {
366 /* lock protects refcnt, everything else is finalized at initialization
371 struct libusb_context *ctx;
375 struct libusb_device* parent_dev;
376 uint8_t device_address;
377 uint8_t num_configurations;
378 enum libusb_speed speed;
380 struct list_head list;
381 unsigned long session_data;
383 struct libusb_device_descriptor device_descriptor;
386 unsigned char os_priv
387 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
388 [] /* valid C99 code */
390 [0] /* non-standard, but usually working code */
392 #if defined(OS_SUNOS)
393 __attribute__ ((aligned (8)));
399 struct libusb_device_handle {
400 /* lock protects claimed_interfaces */
402 unsigned long claimed_interfaces;
404 struct list_head list;
405 struct libusb_device *dev;
406 int auto_detach_kernel_driver;
407 unsigned char os_priv
408 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
409 [] /* valid C99 code */
411 [0] /* non-standard, but usually working code */
413 #if defined(OS_SUNOS)
414 __attribute__ ((aligned (8)));
421 USBI_CLOCK_MONOTONIC,
425 /* in-memory transfer layout:
427 * 1. struct usbi_transfer
428 * 2. struct libusb_transfer (which includes iso packets) [variable size]
429 * 3. os private data [variable size]
431 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
432 * appropriate number of bytes.
433 * the usbi_transfer includes the number of allocated packets, so you can
434 * determine the size of the transfer and hence the start and length of the
438 struct usbi_transfer {
440 struct list_head list;
441 struct list_head completed_list;
442 struct timeval timeout;
445 uint8_t state_flags; /* Protected by usbi_transfer->lock */
446 uint8_t timeout_flags; /* Protected by the flying_stransfers_lock */
448 /* this lock is held during libusb_submit_transfer() and
449 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
450 * cancellation, submission-during-cancellation, etc). the OS backend
451 * should also take this lock in the handle_events path, to prevent the user
452 * cancelling the transfer from another thread while you are processing
453 * its completion (presumably there would be races within your OS backend
454 * if this were possible).
455 * Note paths taking both this and the flying_transfers_lock must
456 * always take the flying_transfers_lock first */
460 enum usbi_transfer_state_flags {
461 /* Transfer successfully submitted by backend */
462 USBI_TRANSFER_IN_FLIGHT = 1 << 0,
464 /* Cancellation was requested via libusb_cancel_transfer() */
465 USBI_TRANSFER_CANCELLING = 1 << 1,
467 /* Operation on the transfer failed because the device disappeared */
468 USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 2,
471 enum usbi_transfer_timeout_flags {
472 /* Set by backend submit_transfer() if the OS handles timeout */
473 USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 0,
475 /* The transfer timeout has been handled */
476 USBI_TRANSFER_TIMEOUT_HANDLED = 1 << 1,
478 /* The transfer timeout was successfully processed */
479 USBI_TRANSFER_TIMED_OUT = 1 << 2,
482 #define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
483 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
484 + sizeof(struct usbi_transfer)))
485 #define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
486 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
487 - sizeof(struct usbi_transfer)))
489 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
491 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
492 + sizeof(struct libusb_transfer)
493 + (transfer->num_iso_packets
494 * sizeof(struct libusb_iso_packet_descriptor));
499 /* All standard descriptors have these 2 fields in common */
500 struct usb_descriptor_header {
502 uint8_t bDescriptorType;
505 /* shared data and functions */
507 int usbi_io_init(struct libusb_context *ctx);
508 void usbi_io_exit(struct libusb_context *ctx);
510 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
511 unsigned long session_id);
512 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
513 unsigned long session_id);
514 int usbi_sanitize_device(struct libusb_device *dev);
515 void usbi_handle_disconnect(struct libusb_device_handle *dev_handle);
517 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
518 enum libusb_transfer_status status);
519 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
520 void usbi_signal_transfer_completion(struct usbi_transfer *transfer);
522 int usbi_parse_descriptor(const unsigned char *source, const char *descriptor,
523 void *dest, int host_endian);
524 int usbi_device_cache_descriptor(libusb_device *dev);
525 int usbi_get_config_index_by_value(struct libusb_device *dev,
526 uint8_t bConfigurationValue, int *idx);
528 void usbi_connect_device (struct libusb_device *dev);
529 void usbi_disconnect_device (struct libusb_device *dev);
531 int usbi_signal_event(struct libusb_context *ctx);
532 int usbi_clear_event(struct libusb_context *ctx);
534 /* Internal abstraction for poll (needs struct usbi_transfer on Windows) */
535 #if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD) || defined(OS_NETBSD) ||\
536 defined(OS_HAIKU) || defined(OS_SUNOS)
538 #include "os/poll_posix.h"
539 #elif defined(OS_WINDOWS) || defined(OS_WINCE)
540 #include "os/poll_windows.h"
543 #if (defined(OS_WINDOWS) || defined(OS_WINCE)) && !defined(__GNUC__)
544 #define snprintf _snprintf
545 #define vsnprintf _vsnprintf
546 int usbi_gettimeofday(struct timeval *tp, void *tzp);
547 #define LIBUSB_GETTIMEOFDAY_WIN32
548 #define HAVE_USBI_GETTIMEOFDAY
550 #ifdef HAVE_GETTIMEOFDAY
551 #define usbi_gettimeofday(tv, tz) gettimeofday((tv), (tz))
552 #define HAVE_USBI_GETTIMEOFDAY
557 /* must come first */
558 struct libusb_pollfd pollfd;
560 struct list_head list;
563 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
564 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
566 /* device discovery */
568 /* we traverse usbfs without knowing how many devices we are going to find.
569 * so we create this discovered_devs model which is similar to a linked-list
570 * which grows when required. it can be freed once discovery has completed,
571 * eliminating the need for a list node in the libusb_device structure
573 struct discovered_devs {
576 struct libusb_device *devices
577 #if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
578 [] /* valid C99 code */
580 [0] /* non-standard, but usually working code */
585 struct discovered_devs *discovered_devs_append(
586 struct discovered_devs *discdevs, struct libusb_device *dev);
590 /* This is the interface that OS backends need to implement.
591 * All fields are mandatory, except ones explicitly noted as optional. */
592 struct usbi_os_backend {
593 /* A human-readable name for your backend, e.g. "Linux usbfs" */
596 /* Binary mask for backend specific capabilities */
599 /* Perform initialization of your backend. You might use this function
600 * to determine specific capabilities of the system, allocate required
601 * data structures for later, etc.
603 * This function is called when a libusb user initializes the library
606 * Return 0 on success, or a LIBUSB_ERROR code on failure.
608 int (*init)(struct libusb_context *ctx);
610 /* Deinitialization. Optional. This function should destroy anything
611 * that was set up by init.
613 * This function is called when the user deinitializes the library.
617 /* Enumerate all the USB devices on the system, returning them in a list
618 * of discovered devices.
620 * Your implementation should enumerate all devices on the system,
621 * regardless of whether they have been seen before or not.
623 * When you have found a device, compute a session ID for it. The session
624 * ID should uniquely represent that particular device for that particular
625 * connection session since boot (i.e. if you disconnect and reconnect a
626 * device immediately after, it should be assigned a different session ID).
627 * If your OS cannot provide a unique session ID as described above,
628 * presenting a session ID of (bus_number << 8 | device_address) should
629 * be sufficient. Bus numbers and device addresses wrap and get reused,
630 * but that is an unlikely case.
632 * After computing a session ID for a device, call
633 * usbi_get_device_by_session_id(). This function checks if libusb already
634 * knows about the device, and if so, it provides you with a reference
635 * to a libusb_device structure for it.
637 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
638 * a new device structure for the device. Call usbi_alloc_device() to
639 * obtain a new libusb_device structure with reference count 1. Populate
640 * the bus_number and device_address attributes of the new device, and
641 * perform any other internal backend initialization you need to do. At
642 * this point, you should be ready to provide device descriptors and so
643 * on through the get_*_descriptor functions. Finally, call
644 * usbi_sanitize_device() to perform some final sanity checks on the
645 * device. Assuming all of the above succeeded, we can now continue.
646 * If any of the above failed, remember to unreference the device that
647 * was returned by usbi_alloc_device().
649 * At this stage we have a populated libusb_device structure (either one
650 * that was found earlier, or one that we have just allocated and
651 * populated). This can now be added to the discovered devices list
652 * using discovered_devs_append(). Note that discovered_devs_append()
653 * may reallocate the list, returning a new location for it, and also
654 * note that reallocation can fail. Your backend should handle these
655 * error conditions appropriately.
657 * This function should not generate any bus I/O and should not block.
658 * If I/O is required (e.g. reading the active configuration value), it is
659 * OK to ignore these suggestions :)
661 * This function is executed when the user wishes to retrieve a list
662 * of USB devices connected to the system.
664 * If the backend has hotplug support, this function is not used!
666 * Return 0 on success, or a LIBUSB_ERROR code on failure.
668 int (*get_device_list)(struct libusb_context *ctx,
669 struct discovered_devs **discdevs);
671 /* Apps which were written before hotplug support, may listen for
672 * hotplug events on their own and call libusb_get_device_list on
673 * device addition. In this case libusb_get_device_list will likely
674 * return a list without the new device in there, as the hotplug
675 * event thread will still be busy enumerating the device, which may
676 * take a while, or may not even have seen the event yet.
678 * To avoid this libusb_get_device_list will call this optional
679 * function for backends with hotplug support before copying
680 * ctx->usb_devs to the user. In this function the backend should
681 * ensure any pending hotplug events are fully processed before
684 * Optional, should be implemented by backends with hotplug support.
686 void (*hotplug_poll)(void);
688 /* Open a device for I/O and other USB operations. The device handle
689 * is preallocated for you, you can retrieve the device in question
690 * through handle->dev.
692 * Your backend should allocate any internal resources required for I/O
693 * and other operations so that those operations can happen (hopefully)
694 * without hiccup. This is also a good place to inform libusb that it
695 * should monitor certain file descriptors related to this device -
696 * see the usbi_add_pollfd() function.
698 * This function should not generate any bus I/O and should not block.
700 * This function is called when the user attempts to obtain a device
701 * handle for a device.
705 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
706 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
708 * - another LIBUSB_ERROR code on other failure
710 * Do not worry about freeing the handle on failed open, the upper layers
713 int (*open)(struct libusb_device_handle *dev_handle);
715 /* Close a device such that the handle cannot be used again. Your backend
716 * should destroy any resources that were allocated in the open path.
717 * This may also be a good place to call usbi_remove_pollfd() to inform
718 * libusb of any file descriptors associated with this device that should
719 * no longer be monitored.
721 * This function is called when the user closes a device handle.
723 void (*close)(struct libusb_device_handle *dev_handle);
725 /* Retrieve the device descriptor from a device.
727 * The descriptor should be retrieved from memory, NOT via bus I/O to the
728 * device. This means that you may have to cache it in a private structure
729 * during get_device_list enumeration. Alternatively, you may be able
730 * to retrieve it from a kernel interface (some Linux setups can do this)
731 * still without generating bus I/O.
733 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
734 * buffer, which is guaranteed to be big enough.
736 * This function is called when sanity-checking a device before adding
737 * it to the list of discovered devices, and also when the user requests
738 * to read the device descriptor.
740 * This function is expected to return the descriptor in bus-endian format
741 * (LE). If it returns the multi-byte values in host-endian format,
742 * set the host_endian output parameter to "1".
744 * Return 0 on success or a LIBUSB_ERROR code on failure.
746 int (*get_device_descriptor)(struct libusb_device *device,
747 unsigned char *buffer, int *host_endian);
749 /* Get the ACTIVE configuration descriptor for a device.
751 * The descriptor should be retrieved from memory, NOT via bus I/O to the
752 * device. This means that you may have to cache it in a private structure
753 * during get_device_list enumeration. You may also have to keep track
754 * of which configuration is active when the user changes it.
756 * This function is expected to write len bytes of data into buffer, which
757 * is guaranteed to be big enough. If you can only do a partial write,
758 * return an error code.
760 * This function is expected to return the descriptor in bus-endian format
761 * (LE). If it returns the multi-byte values in host-endian format,
762 * set the host_endian output parameter to "1".
766 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
767 * - another LIBUSB_ERROR code on other failure
769 int (*get_active_config_descriptor)(struct libusb_device *device,
770 unsigned char *buffer, size_t len, int *host_endian);
772 /* Get a specific configuration descriptor for a device.
774 * The descriptor should be retrieved from memory, NOT via bus I/O to the
775 * device. This means that you may have to cache it in a private structure
776 * during get_device_list enumeration.
778 * The requested descriptor is expressed as a zero-based index (i.e. 0
779 * indicates that we are requesting the first descriptor). The index does
780 * not (necessarily) equal the bConfigurationValue of the configuration
783 * This function is expected to write len bytes of data into buffer, which
784 * is guaranteed to be big enough. If you can only do a partial write,
785 * return an error code.
787 * This function is expected to return the descriptor in bus-endian format
788 * (LE). If it returns the multi-byte values in host-endian format,
789 * set the host_endian output parameter to "1".
791 * Return the length read on success or a LIBUSB_ERROR code on failure.
793 int (*get_config_descriptor)(struct libusb_device *device,
794 uint8_t config_index, unsigned char *buffer, size_t len,
797 /* Like get_config_descriptor but then by bConfigurationValue instead
800 * Optional, if not present the core will call get_config_descriptor
801 * for all configs until it finds the desired bConfigurationValue.
803 * Returns a pointer to the raw-descriptor in *buffer, this memory
804 * is valid as long as device is valid.
806 * Returns the length of the returned raw-descriptor on success,
807 * or a LIBUSB_ERROR code on failure.
809 int (*get_config_descriptor_by_value)(struct libusb_device *device,
810 uint8_t bConfigurationValue, unsigned char **buffer,
813 /* Get the bConfigurationValue for the active configuration for a device.
814 * Optional. This should only be implemented if you can retrieve it from
815 * cache (don't generate I/O).
817 * If you cannot retrieve this from cache, either do not implement this
818 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
819 * libusb to retrieve the information through a standard control transfer.
821 * This function must be non-blocking.
824 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
826 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
828 * - another LIBUSB_ERROR code on other failure.
830 int (*get_configuration)(struct libusb_device_handle *dev_handle, int *config);
832 /* Set the active configuration for a device.
834 * A configuration value of -1 should put the device in unconfigured state.
836 * This function can block.
840 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
841 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
842 * configuration cannot be changed)
843 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
845 * - another LIBUSB_ERROR code on other failure.
847 int (*set_configuration)(struct libusb_device_handle *dev_handle, int config);
849 /* Claim an interface. When claimed, the application can then perform
850 * I/O to an interface's endpoints.
852 * This function should not generate any bus I/O and should not block.
853 * Interface claiming is a logical operation that simply ensures that
854 * no other drivers/applications are using the interface, and after
855 * claiming, no other drivers/applications can use the interface because
860 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
861 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
862 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
864 * - another LIBUSB_ERROR code on other failure
866 int (*claim_interface)(struct libusb_device_handle *dev_handle, int interface_number);
868 /* Release a previously claimed interface.
870 * This function should also generate a SET_INTERFACE control request,
871 * resetting the alternate setting of that interface to 0. It's OK for
872 * this function to block as a result.
874 * You will only ever be asked to release an interface which was
875 * successfully claimed earlier.
879 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
881 * - another LIBUSB_ERROR code on other failure
883 int (*release_interface)(struct libusb_device_handle *dev_handle, int interface_number);
885 /* Set the alternate setting for an interface.
887 * You will only ever be asked to set the alternate setting for an
888 * interface which was successfully claimed earlier.
890 * It's OK for this function to block.
894 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
895 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
897 * - another LIBUSB_ERROR code on other failure
899 int (*set_interface_altsetting)(struct libusb_device_handle *dev_handle,
900 int interface_number, int altsetting);
902 /* Clear a halt/stall condition on an endpoint.
904 * It's OK for this function to block.
908 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
909 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
911 * - another LIBUSB_ERROR code on other failure
913 int (*clear_halt)(struct libusb_device_handle *dev_handle,
914 unsigned char endpoint);
916 /* Perform a USB port reset to reinitialize a device.
918 * If possible, the device handle should still be usable after the reset
919 * completes, assuming that the device descriptors did not change during
920 * reset and all previous interface state can be restored.
922 * If something changes, or you cannot easily locate/verify the resetted
923 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
924 * to close the old handle and re-enumerate the device.
928 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
929 * has been disconnected since it was opened
930 * - another LIBUSB_ERROR code on other failure
932 int (*reset_device)(struct libusb_device_handle *dev_handle);
934 /* Alloc num_streams usb3 bulk streams on the passed in endpoints */
935 int (*alloc_streams)(struct libusb_device_handle *dev_handle,
936 uint32_t num_streams, unsigned char *endpoints, int num_endpoints);
938 /* Free usb3 bulk streams allocated with alloc_streams */
939 int (*free_streams)(struct libusb_device_handle *dev_handle,
940 unsigned char *endpoints, int num_endpoints);
942 /* Allocate persistent DMA memory for the given device, suitable for
943 * zerocopy. May return NULL on failure. Optional to implement.
945 unsigned char *(*dev_mem_alloc)(struct libusb_device_handle *handle,
948 /* Free memory allocated by dev_mem_alloc. */
949 int (*dev_mem_free)(struct libusb_device_handle *handle,
950 unsigned char *buffer, size_t len);
952 /* Determine if a kernel driver is active on an interface. Optional.
954 * The presence of a kernel driver on an interface indicates that any
955 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
958 * - 0 if no driver is active
959 * - 1 if a driver is active
960 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
962 * - another LIBUSB_ERROR code on other failure
964 int (*kernel_driver_active)(struct libusb_device_handle *dev_handle,
965 int interface_number);
967 /* Detach a kernel driver from an interface. Optional.
969 * After detaching a kernel driver, the interface should be available
974 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
975 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
976 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
978 * - another LIBUSB_ERROR code on other failure
980 int (*detach_kernel_driver)(struct libusb_device_handle *dev_handle,
981 int interface_number);
983 /* Attach a kernel driver to an interface. Optional.
985 * Reattach a kernel driver to the device.
989 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
990 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
991 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
993 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
994 * preventing reattachment
995 * - another LIBUSB_ERROR code on other failure
997 int (*attach_kernel_driver)(struct libusb_device_handle *dev_handle,
998 int interface_number);
1000 /* Destroy a device. Optional.
1002 * This function is called when the last reference to a device is
1003 * destroyed. It should free any resources allocated in the get_device_list
1006 void (*destroy_device)(struct libusb_device *dev);
1008 /* Submit a transfer. Your implementation should take the transfer,
1009 * morph it into whatever form your platform requires, and submit it
1012 * This function must not block.
1014 * This function gets called with the flying_transfers_lock locked!
1018 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1019 * - another LIBUSB_ERROR code on other failure
1021 int (*submit_transfer)(struct usbi_transfer *itransfer);
1023 /* Cancel a previously submitted transfer.
1025 * This function must not block. The transfer cancellation must complete
1026 * later, resulting in a call to usbi_handle_transfer_cancellation()
1027 * from the context of handle_events.
1029 int (*cancel_transfer)(struct usbi_transfer *itransfer);
1031 /* Clear a transfer as if it has completed or cancelled, but do not
1032 * report any completion/cancellation to the library. You should free
1033 * all private data from the transfer as if you were just about to report
1034 * completion or cancellation.
1036 * This function might seem a bit out of place. It is used when libusb
1037 * detects a disconnected device - it calls this function for all pending
1038 * transfers before reporting completion (with the disconnect code) to
1039 * the user. Maybe we can improve upon this internal interface in future.
1041 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
1043 /* Handle any pending events on file descriptors. Optional.
1045 * Provide this function when file descriptors directly indicate device
1046 * or transfer activity. If your backend does not have such file descriptors,
1047 * implement the handle_transfer_completion function below.
1049 * This involves monitoring any active transfers and processing their
1050 * completion or cancellation.
1052 * The function is passed an array of pollfd structures (size nfds)
1053 * as a result of the poll() system call. The num_ready parameter
1054 * indicates the number of file descriptors that have reported events
1055 * (i.e. the poll() return value). This should be enough information
1056 * for you to determine which actions need to be taken on the currently
1059 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
1060 * For completed transfers, call usbi_handle_transfer_completion().
1061 * For control/bulk/interrupt transfers, populate the "transferred"
1062 * element of the appropriate usbi_transfer structure before calling the
1063 * above functions. For isochronous transfers, populate the status and
1064 * transferred fields of the iso packet descriptors of the transfer.
1066 * This function should also be able to detect disconnection of the
1067 * device, reporting that situation with usbi_handle_disconnect().
1069 * When processing an event related to a transfer, you probably want to
1070 * take usbi_transfer.lock to prevent races. See the documentation for
1071 * the usbi_transfer structure.
1073 * Return 0 on success, or a LIBUSB_ERROR code on failure.
1075 int (*handle_events)(struct libusb_context *ctx,
1076 struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
1078 /* Handle transfer completion. Optional.
1080 * Provide this function when there are no file descriptors available
1081 * that directly indicate device or transfer activity. If your backend does
1082 * have such file descriptors, implement the handle_events function above.
1084 * Your backend must tell the library when a transfer has completed by
1085 * calling usbi_signal_transfer_completion(). You should store any private
1086 * information about the transfer and its completion status in the transfer's
1087 * private backend data.
1089 * During event handling, this function will be called on each transfer for
1090 * which usbi_signal_transfer_completion() was called.
1092 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
1093 * For completed transfers, call usbi_handle_transfer_completion().
1094 * For control/bulk/interrupt transfers, populate the "transferred"
1095 * element of the appropriate usbi_transfer structure before calling the
1096 * above functions. For isochronous transfers, populate the status and
1097 * transferred fields of the iso packet descriptors of the transfer.
1099 * Return 0 on success, or a LIBUSB_ERROR code on failure.
1101 int (*handle_transfer_completion)(struct usbi_transfer *itransfer);
1103 /* Get time from specified clock. At least two clocks must be implemented
1104 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
1106 Description of clocks:
1107 USBI_CLOCK_REALTIME : clock returns time since system epoch.
1108 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
1109 time (usually boot).
1111 int (*clock_gettime)(int clkid, struct timespec *tp);
1113 #ifdef USBI_TIMERFD_AVAILABLE
1114 /* clock ID of the clock that should be used for timerfd */
1115 clockid_t (*get_timerfd_clockid)(void);
1118 /* Number of bytes to reserve for per-device private backend data.
1119 * This private data area is accessible through the "os_priv" field of
1120 * struct libusb_device. */
1121 size_t device_priv_size;
1123 /* Number of bytes to reserve for per-handle private backend data.
1124 * This private data area is accessible through the "os_priv" field of
1125 * struct libusb_device. */
1126 size_t device_handle_priv_size;
1128 /* Number of bytes to reserve for per-transfer private backend data.
1129 * This private data area is accessible by calling
1130 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
1132 size_t transfer_priv_size;
1135 extern const struct usbi_os_backend * const usbi_backend;
1137 extern const struct usbi_os_backend linux_usbfs_backend;
1138 extern const struct usbi_os_backend darwin_backend;
1139 extern const struct usbi_os_backend openbsd_backend;
1140 extern const struct usbi_os_backend netbsd_backend;
1141 extern const struct usbi_os_backend windows_backend;
1142 extern const struct usbi_os_backend usbdk_backend;
1143 extern const struct usbi_os_backend wince_backend;
1144 extern const struct usbi_os_backend haiku_usb_raw_backend;
1145 extern const struct usbi_os_backend sunos_backend;
1147 extern struct list_head active_contexts_list;
1148 extern usbi_mutex_static_t active_contexts_lock;