2 * Internal header for libusb
3 * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
4 * Copyright (c) 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
33 #define DEVICE_DESC_LENGTH 18
35 #define USB_MAXENDPOINTS 32
36 #define USB_MAXINTERFACES 32
37 #define USB_MAXCONFIG 8
40 struct list_head *prev, *next;
43 /* Get an entry from the list
44 * ptr - the address of this list_head element in "type"
45 * type - the data type that contains "member"
46 * member - the list_head element in "type"
48 #define list_entry(ptr, type, member) \
49 ((type *)((uintptr_t)(ptr) - (uintptr_t)(&((type *)0L)->member)))
51 /* Get each entry from a list
52 * pos - A structure pointer has a "member" element
54 * member - the list_head element in "pos"
55 * type - the type of the first parameter
57 #define list_for_each_entry(pos, head, member, type) \
58 for (pos = list_entry((head)->next, type, member); \
59 &pos->member != (head); \
60 pos = list_entry(pos->member.next, type, member))
62 #define list_for_each_entry_safe(pos, n, head, member, type) \
63 for (pos = list_entry((head)->next, type, member), \
64 n = list_entry(pos->member.next, type, member); \
65 &pos->member != (head); \
66 pos = n, n = list_entry(n->member.next, type, member))
68 #define list_empty(entry) ((entry)->next == (entry))
70 static inline void list_init(struct list_head *entry)
72 entry->prev = entry->next = entry;
75 static inline void list_add(struct list_head *entry, struct list_head *head)
77 entry->next = head->next;
80 head->next->prev = entry;
84 static inline void list_add_tail(struct list_head *entry,
85 struct list_head *head)
88 entry->prev = head->prev;
90 head->prev->next = entry;
94 static inline void list_del(struct list_head *entry)
96 entry->next->prev = entry->prev;
97 entry->prev->next = entry->next;
100 #define container_of(ptr, type, member) ({ \
101 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
102 (type *)( (char *)__mptr - offsetof(type,member) );})
104 #define MIN(a, b) ((a) < (b) ? (a) : (b))
105 #define MAX(a, b) ((a) > (b) ? (a) : (b))
107 #define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
109 enum usbi_log_level {
116 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
117 const char *function, const char *format, ...);
119 #if !defined(_MSC_VER) || _MSC_VER > 1200
121 #ifdef ENABLE_LOGGING
122 #define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
124 #define _usbi_log(ctx, level, ...)
127 #ifdef ENABLE_DEBUG_LOGGING
128 #define usbi_dbg(...) _usbi_log(NULL, LOG_LEVEL_DEBUG, __VA_ARGS__)
130 #define usbi_dbg(...)
133 #define usbi_info(ctx, ...) _usbi_log(ctx, LOG_LEVEL_INFO, __VA_ARGS__)
134 #define usbi_warn(ctx, ...) _usbi_log(ctx, LOG_LEVEL_WARNING, __VA_ARGS__)
135 #define usbi_err(ctx, ...) _usbi_log(ctx, LOG_LEVEL_ERROR, __VA_ARGS__)
137 #else /* !defined(_MSC_VER) || _MSC_VER > 1200 */
139 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
140 const char *function, const char *format, va_list args);
142 #ifdef ENABLE_LOGGING
143 #define LOG_BODY(ctxt, level) \
146 va_start (args, format); \
147 usbi_log_v(ctxt, level, "", format, args); \
151 #define LOG_BODY(ctxt, level) { }
154 static inline void usbi_info(struct libusb_context *ctx, const char *format,
156 LOG_BODY(ctx,LOG_LEVEL_INFO)
157 static inline void usbi_warn(struct libusb_context *ctx, const char *format,
159 LOG_BODY(ctx,LOG_LEVEL_WARNING)
160 static inline void usbi_err( struct libusb_context *ctx, const char *format,
162 LOG_BODY(ctx,LOG_LEVEL_ERROR)
164 static inline void usbi_dbg(const char *format, ...)
165 #ifdef ENABLE_DEBUG_LOGGING
166 LOG_BODY(NULL,LOG_LEVEL_DEBUG)
171 #endif /* !defined(_MSC_VER) || _MSC_VER > 1200 */
173 #define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
174 #define DEVICE_CTX(dev) ((dev)->ctx)
175 #define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
176 #define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
177 #define ITRANSFER_CTX(transfer) \
178 (TRANSFER_CTX(__USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
180 /* Internal abstraction for thread synchronization */
181 #if defined(OS_LINUX) || defined(OS_DARWIN)
182 #include <os/threads_posix.h>
185 extern struct libusb_context *usbi_default_context;
187 struct libusb_context {
191 /* internal control pipe, used for interrupting event handling when
192 * something needs to modify poll fds. */
195 struct list_head usb_devs;
196 usbi_mutex_t usb_devs_lock;
198 /* A list of open handles. Backends are free to traverse this if required.
200 struct list_head open_devs;
201 usbi_mutex_t open_devs_lock;
203 /* this is a list of in-flight transfer handles, sorted by timeout
204 * expiration. URBs to timeout the soonest are placed at the beginning of
205 * the list, URBs that will time out later are placed after, and urbs with
206 * infinite timeout are always placed at the very end. */
207 struct list_head flying_transfers;
208 usbi_mutex_t flying_transfers_lock;
210 /* list of poll fds */
211 struct list_head pollfds;
212 usbi_mutex_t pollfds_lock;
214 /* a counter that is set when we want to interrupt event handling, in order
215 * to modify the poll fd set. and a lock to protect it. */
216 unsigned int pollfd_modify;
217 usbi_mutex_t pollfd_modify_lock;
219 /* user callbacks for pollfd changes */
220 libusb_pollfd_added_cb fd_added_cb;
221 libusb_pollfd_removed_cb fd_removed_cb;
222 void *fd_cb_user_data;
224 /* ensures that only one thread is handling events at any one time */
225 usbi_mutex_t events_lock;
227 /* used to see if there is an active thread doing event handling */
228 int event_handler_active;
230 /* used to wait for event completion in threads other than the one that is
232 usbi_mutex_t event_waiters_lock;
233 usbi_cond_t event_waiters_cond;
235 #ifdef USBI_TIMERFD_AVAILABLE
236 /* used for timeout handling, if supported by OS.
237 * this timerfd is maintained to trigger on the next pending timeout */
242 #ifdef USBI_TIMERFD_AVAILABLE
243 #define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
245 #define usbi_using_timerfd(ctx) (0)
248 struct libusb_device {
249 /* lock protects refcnt, everything else is finalized at initialization
254 struct libusb_context *ctx;
257 uint8_t device_address;
258 uint8_t num_configurations;
260 struct list_head list;
261 unsigned long session_data;
262 unsigned char os_priv[0];
265 struct libusb_device_handle {
266 /* lock protects claimed_interfaces */
268 unsigned long claimed_interfaces;
270 struct list_head list;
271 struct libusb_device *dev;
272 unsigned char os_priv[0];
275 #define USBI_TRANSFER_TIMED_OUT (1<<0)
278 USBI_CLOCK_MONOTONIC,
282 /* in-memory transfer layout:
284 * 1. struct usbi_transfer
285 * 2. struct libusb_transfer (which includes iso packets) [variable size]
286 * 3. os private data [variable size]
288 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
289 * appropriate number of bytes.
290 * the usbi_transfer includes the number of allocated packets, so you can
291 * determine the size of the transfer and hence the start and length of the
295 struct usbi_transfer {
297 struct list_head list;
298 struct timeval timeout;
302 /* this lock is held during libusb_submit_transfer() and
303 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
304 * cancellation, submission-during-cancellation, etc). the OS backend
305 * should also take this lock in the handle_events path, to prevent the user
306 * cancelling the transfer from another thread while you are processing
307 * its completion (presumably there would be races within your OS backend
308 * if this were possible). */
312 #define __USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
313 ((struct libusb_transfer *)(((unsigned char *)(transfer)) \
314 + sizeof(struct usbi_transfer)))
315 #define __LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
316 ((struct usbi_transfer *)(((unsigned char *)(transfer)) \
317 - sizeof(struct usbi_transfer)))
319 static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
321 return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
322 + sizeof(struct libusb_transfer)
323 + (transfer->num_iso_packets
324 * sizeof(struct libusb_iso_packet_descriptor));
329 /* All standard descriptors have these 2 fields in common */
330 struct usb_descriptor_header {
332 uint8_t bDescriptorType;
335 /* shared data and functions */
337 int usbi_io_init(struct libusb_context *ctx);
338 void usbi_io_exit(struct libusb_context *ctx);
340 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
341 unsigned long session_id);
342 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
343 unsigned long session_id);
344 int usbi_sanitize_device(struct libusb_device *dev);
345 void usbi_handle_disconnect(struct libusb_device_handle *handle);
347 int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
348 enum libusb_transfer_status status);
349 int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
351 int usbi_parse_descriptor(unsigned char *source, char *descriptor, void *dest,
353 int usbi_get_config_index_by_value(struct libusb_device *dev,
354 uint8_t bConfigurationValue, int *idx);
359 /* must come first */
360 struct libusb_pollfd pollfd;
362 struct list_head list;
365 int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
366 void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
368 /* device discovery */
370 /* we traverse usbfs without knowing how many devices we are going to find.
371 * so we create this discovered_devs model which is similar to a linked-list
372 * which grows when required. it can be freed once discovery has completed,
373 * eliminating the need for a list node in the libusb_device structure
375 struct discovered_devs {
378 struct libusb_device *devices[0];
381 struct discovered_devs *discovered_devs_append(
382 struct discovered_devs *discdevs, struct libusb_device *dev);
386 /* This is the interface that OS backends need to implement.
387 * All fields are mandatory, except ones explicitly noted as optional. */
388 struct usbi_os_backend {
389 /* A human-readable name for your backend, e.g. "Linux usbfs" */
392 /* Perform initialization of your backend. You might use this function
393 * to determine specific capabilities of the system, allocate required
394 * data structures for later, etc.
396 * This function is called when a libusb user initializes the library
399 * Return 0 on success, or a LIBUSB_ERROR code on failure.
401 int (*init)(struct libusb_context *ctx);
403 /* Deinitialization. Optional. This function should destroy anything
404 * that was set up by init.
406 * This function is called when the user deinitializes the library.
410 /* Enumerate all the USB devices on the system, returning them in a list
411 * of discovered devices.
413 * Your implementation should enumerate all devices on the system,
414 * regardless of whether they have been seen before or not.
416 * When you have found a device, compute a session ID for it. The session
417 * ID should uniquely represent that particular device for that particular
418 * connection session since boot (i.e. if you disconnect and reconnect a
419 * device immediately after, it should be assigned a different session ID).
420 * If your OS cannot provide a unique session ID as described above,
421 * presenting a session ID of (bus_number << 8 | device_address) should
422 * be sufficient. Bus numbers and device addresses wrap and get reused,
423 * but that is an unlikely case.
425 * After computing a session ID for a device, call
426 * usbi_get_device_by_session_id(). This function checks if libusb already
427 * knows about the device, and if so, it provides you with a libusb_device
430 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
431 * a new device structure for the device. Call usbi_alloc_device() to
432 * obtain a new libusb_device structure with reference count 1. Populate
433 * the bus_number and device_address attributes of the new device, and
434 * perform any other internal backend initialization you need to do. At
435 * this point, you should be ready to provide device descriptors and so
436 * on through the get_*_descriptor functions. Finally, call
437 * usbi_sanitize_device() to perform some final sanity checks on the
438 * device. Assuming all of the above succeeded, we can now continue.
439 * If any of the above failed, remember to unreference the device that
440 * was returned by usbi_alloc_device().
442 * At this stage we have a populated libusb_device structure (either one
443 * that was found earlier, or one that we have just allocated and
444 * populated). This can now be added to the discovered devices list
445 * using discovered_devs_append(). Note that discovered_devs_append()
446 * may reallocate the list, returning a new location for it, and also
447 * note that reallocation can fail. Your backend should handle these
448 * error conditions appropriately.
450 * This function should not generate any bus I/O and should not block.
451 * If I/O is required (e.g. reading the active configuration value), it is
452 * OK to ignore these suggestions :)
454 * This function is executed when the user wishes to retrieve a list
455 * of USB devices connected to the system.
457 * Return 0 on success, or a LIBUSB_ERROR code on failure.
459 int (*get_device_list)(struct libusb_context *ctx,
460 struct discovered_devs **discdevs);
462 /* Open a device for I/O and other USB operations. The device handle
463 * is preallocated for you, you can retrieve the device in question
464 * through handle->dev.
466 * Your backend should allocate any internal resources required for I/O
467 * and other operations so that those operations can happen (hopefully)
468 * without hiccup. This is also a good place to inform libusb that it
469 * should monitor certain file descriptors related to this device -
470 * see the usbi_add_pollfd() function.
472 * This function should not generate any bus I/O and should not block.
474 * This function is called when the user attempts to obtain a device
475 * handle for a device.
479 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
480 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
482 * - another LIBUSB_ERROR code on other failure
484 * Do not worry about freeing the handle on failed open, the upper layers
487 int (*open)(struct libusb_device_handle *handle);
489 /* Close a device such that the handle cannot be used again. Your backend
490 * should destroy any resources that were allocated in the open path.
491 * This may also be a good place to call usbi_remove_pollfd() to inform
492 * libusb of any file descriptors associated with this device that should
493 * no longer be monitored.
495 * This function is called when the user closes a device handle.
497 void (*close)(struct libusb_device_handle *handle);
499 /* Retrieve the device descriptor from a device.
501 * The descriptor should be retrieved from memory, NOT via bus I/O to the
502 * device. This means that you may have to cache it in a private structure
503 * during get_device_list enumeration. Alternatively, you may be able
504 * to retrieve it from a kernel interface (some Linux setups can do this)
505 * still without generating bus I/O.
507 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
508 * buffer, which is guaranteed to be big enough.
510 * This function is called when sanity-checking a device before adding
511 * it to the list of discovered devices, and also when the user requests
512 * to read the device descriptor.
514 * This function is expected to return the descriptor in bus-endian format
515 * (LE). If it returns the multi-byte values in host-endian format,
516 * set the host_endian output parameter to "1".
518 * Return 0 on success or a LIBUSB_ERROR code on failure.
520 int (*get_device_descriptor)(struct libusb_device *device,
521 unsigned char *buffer, int *host_endian);
523 /* Get the ACTIVE configuration descriptor for a device.
525 * The descriptor should be retrieved from memory, NOT via bus I/O to the
526 * device. This means that you may have to cache it in a private structure
527 * during get_device_list enumeration. You may also have to keep track
528 * of which configuration is active when the user changes it.
530 * This function is expected to write len bytes of data into buffer, which
531 * is guaranteed to be big enough. If you can only do a partial write,
532 * return an error code.
534 * This function is expected to return the descriptor in bus-endian format
535 * (LE). If it returns the multi-byte values in host-endian format,
536 * set the host_endian output parameter to "1".
540 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
541 * - another LIBUSB_ERROR code on other failure
543 int (*get_active_config_descriptor)(struct libusb_device *device,
544 unsigned char *buffer, size_t len, int *host_endian);
546 /* Get a specific configuration descriptor for a device.
548 * The descriptor should be retrieved from memory, NOT via bus I/O to the
549 * device. This means that you may have to cache it in a private structure
550 * during get_device_list enumeration.
552 * The requested descriptor is expressed as a zero-based index (i.e. 0
553 * indicates that we are requesting the first descriptor). The index does
554 * not (necessarily) equal the bConfigurationValue of the configuration
557 * This function is expected to write len bytes of data into buffer, which
558 * is guaranteed to be big enough. If you can only do a partial write,
559 * return an error code.
561 * This function is expected to return the descriptor in bus-endian format
562 * (LE). If it returns the multi-byte values in host-endian format,
563 * set the host_endian output parameter to "1".
565 * Return 0 on success or a LIBUSB_ERROR code on failure.
567 int (*get_config_descriptor)(struct libusb_device *device,
568 uint8_t config_index, unsigned char *buffer, size_t len,
571 /* Get the bConfigurationValue for the active configuration for a device.
572 * Optional. This should only be implemented if you can retrieve it from
573 * cache (don't generate I/O).
575 * If you cannot retrieve this from cache, either do not implement this
576 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
577 * libusb to retrieve the information through a standard control transfer.
579 * This function must be non-blocking.
582 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
584 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
586 * - another LIBUSB_ERROR code on other failure.
588 int (*get_configuration)(struct libusb_device_handle *handle, int *config);
590 /* Set the active configuration for a device.
592 * A configuration value of -1 should put the device in unconfigured state.
594 * This function can block.
598 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
599 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
600 * configuration cannot be changed)
601 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
603 * - another LIBUSB_ERROR code on other failure.
605 int (*set_configuration)(struct libusb_device_handle *handle, int config);
607 /* Claim an interface. When claimed, the application can then perform
608 * I/O to an interface's endpoints.
610 * This function should not generate any bus I/O and should not block.
611 * Interface claiming is a logical operation that simply ensures that
612 * no other drivers/applications are using the interface, and after
613 * claiming, no other drivers/applicatiosn can use the interface because
618 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
619 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
620 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
622 * - another LIBUSB_ERROR code on other failure
624 int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
626 /* Release a previously claimed interface.
628 * This function should also generate a SET_INTERFACE control request,
629 * resetting the alternate setting of that interface to 0. It's OK for
630 * this function to block as a result.
632 * You will only ever be asked to release an interface which was
633 * successfully claimed earlier.
637 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
639 * - another LIBUSB_ERROR code on other failure
641 int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
643 /* Set the alternate setting for an interface.
645 * You will only ever be asked to set the alternate setting for an
646 * interface which was successfully claimed earlier.
648 * It's OK for this function to block.
652 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
653 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
655 * - another LIBUSB_ERROR code on other failure
657 int (*set_interface_altsetting)(struct libusb_device_handle *handle,
658 int interface_number, int altsetting);
660 /* Clear a halt/stall condition on an endpoint.
662 * It's OK for this function to block.
666 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
667 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
669 * - another LIBUSB_ERROR code on other failure
671 int (*clear_halt)(struct libusb_device_handle *handle,
672 unsigned char endpoint);
674 /* Perform a USB port reset to reinitialize a device.
676 * If possible, the handle should still be usable after the reset
677 * completes, assuming that the device descriptors did not change during
678 * reset and all previous interface state can be restored.
680 * If something changes, or you cannot easily locate/verify the resetted
681 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
682 * to close the old handle and re-enumerate the device.
686 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
687 * has been disconnected since it was opened
688 * - another LIBUSB_ERROR code on other failure
690 int (*reset_device)(struct libusb_device_handle *handle);
692 /* Determine if a kernel driver is active on an interface. Optional.
694 * The presence of a kernel driver on an interface indicates that any
695 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
698 * - 0 if no driver is active
699 * - 1 if a driver is active
700 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
702 * - another LIBUSB_ERROR code on other failure
704 int (*kernel_driver_active)(struct libusb_device_handle *handle,
705 int interface_number);
707 /* Detach a kernel driver from an interface. Optional.
709 * After detaching a kernel driver, the interface should be available
714 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
715 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
716 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
718 * - another LIBUSB_ERROR code on other failure
720 int (*detach_kernel_driver)(struct libusb_device_handle *handle,
721 int interface_number);
723 /* Attach a kernel driver to an interface. Optional.
725 * Reattach a kernel driver to the device.
729 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
730 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
731 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
733 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
734 * preventing reattachment
735 * - another LIBUSB_ERROR code on other failure
737 int (*attach_kernel_driver)(struct libusb_device_handle *handle,
738 int interface_number);
740 /* Destroy a device. Optional.
742 * This function is called when the last reference to a device is
743 * destroyed. It should free any resources allocated in the get_device_list
746 void (*destroy_device)(struct libusb_device *dev);
748 /* Submit a transfer. Your implementation should take the transfer,
749 * morph it into whatever form your platform requires, and submit it
752 * This function must not block.
756 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
757 * - another LIBUSB_ERROR code on other failure
759 int (*submit_transfer)(struct usbi_transfer *itransfer);
761 /* Cancel a previously submitted transfer.
763 * This function must not block. The transfer cancellation must complete
764 * later, resulting in a call to usbi_handle_transfer_cancellation()
765 * from the context of handle_events.
767 int (*cancel_transfer)(struct usbi_transfer *itransfer);
769 /* Clear a transfer as if it has completed or cancelled, but do not
770 * report any completion/cancellation to the library. You should free
771 * all private data from the transfer as if you were just about to report
772 * completion or cancellation.
774 * This function might seem a bit out of place. It is used when libusb
775 * detects a disconnected device - it calls this function for all pending
776 * transfers before reporting completion (with the disconnect code) to
777 * the user. Maybe we can improve upon this internal interface in future.
779 void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
781 /* Handle any pending events. This involves monitoring any active
782 * transfers and processing their completion or cancellation.
784 * The function is passed an array of pollfd structures (size nfds)
785 * as a result of the poll() system call. The num_ready parameter
786 * indicates the number of file descriptors that have reported events
787 * (i.e. the poll() return value). This should be enough information
788 * for you to determine which actions need to be taken on the currently
791 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
792 * For completed transfers, call usbi_handle_transfer_completion().
793 * For control/bulk/interrupt transfers, populate the "transferred"
794 * element of the appropriate usbi_transfer structure before calling the
795 * above functions. For isochronous transfers, populate the status and
796 * transferred fields of the iso packet descriptors of the transfer.
798 * This function should also be able to detect disconnection of the
799 * device, reporting that situation with usbi_handle_disconnect().
801 * When processing an event related to a transfer, you probably want to
802 * take usbi_transfer.lock to prevent races. See the documentation for
803 * the usbi_transfer structure.
805 * Return 0 on success, or a LIBUSB_ERROR code on failure.
807 int (*handle_events)(struct libusb_context *ctx,
808 struct pollfd *fds, nfds_t nfds, int num_ready);
810 /* Get time from specified clock. At least two clocks must be implemented
811 by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
813 Description of clocks:
814 USBI_CLOCK_REALTIME : clock returns time since system epoch.
815 USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
818 int (*clock_gettime)(int clkid, struct timespec *tp);
820 #ifdef USBI_TIMERFD_AVAILABLE
821 /* clock ID of the clock that should be used for timerfd */
822 clockid_t (*get_timerfd_clockid)(void);
825 /* Number of bytes to reserve for per-device private backend data.
826 * This private data area is accessible through the "os_priv" field of
827 * struct libusb_device. */
828 size_t device_priv_size;
830 /* Number of bytes to reserve for per-handle private backend data.
831 * This private data area is accessible through the "os_priv" field of
832 * struct libusb_device. */
833 size_t device_handle_priv_size;
835 /* Number of bytes to reserve for per-transfer private backend data.
836 * This private data area is accessible by calling
837 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
839 size_t transfer_priv_size;
841 /* Mumber of additional bytes for os_priv for each iso packet.
842 * Can your backend use this? */
843 /* FIXME: linux can't use this any more. if other OS's cannot either,
844 * then remove this */
845 size_t add_iso_packet_size;
848 extern const struct usbi_os_backend * const usbi_backend;
850 extern const struct usbi_os_backend linux_usbfs_backend;
851 extern const struct usbi_os_backend darwin_backend;