1/*
2 * Internal header for libusbx
3 * Copyright © 2007-2009 Daniel Drake <dsd@gentoo.org>
4 * Copyright © 2001 Johannes Erdfelt <johannes@erdfelt.com>
5 *
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.
10 *
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.
15 *
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
19 */
20
21#ifndef LIBUSBI_H
22#define LIBUSBI_H
23
24#include "config.h"
25
26#include <stdlib.h>
27
28#include <stddef.h>
29#include <stdint.h>
30#include <time.h>
31#include <stdarg.h>
32#ifdef HAVE_POLL_H
33#include <poll.h>
34#endif
35
36#ifdef HAVE_MISSING_H
37#include "missing.h"
38#endif
39#include "libusb.h"
40#include "version.h"
41
42/* Inside the libusbx 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 libusbx public header, mark all declarations as:
47 *   return_type LIBUSB_CALL function_name(params);
48 */
49#define API_EXPORTED LIBUSB_CALL DEFAULT_VISIBILITY
50
51#define DEVICE_DESC_LENGTH		18
52
53#define USB_MAXENDPOINTS	32
54#define USB_MAXINTERFACES	32
55#define USB_MAXCONFIG		8
56
57/* Backend specific capabilities */
58#define USBI_CAP_HAS_HID_ACCESS					0x00010000
59#define USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER	0x00020000
60
61/* Maximum number of bytes in a log line */
62#define USBI_MAX_LOG_LEN	1024
63/* Terminator for log lines */
64#define USBI_LOG_LINE_END	"\n"
65
66/* The following is used to silence warnings for unused variables */
67#define UNUSED(var)			do { (void)(var); } while(0)
68
69#if !defined(ARRAYSIZE)
70#define ARRAYSIZE(array) (sizeof(array)/sizeof(array[0]))
71#endif
72
73struct list_head {
74	struct list_head *prev, *next;
75};
76
77/* Get an entry from the list
78 *  ptr - the address of this list_head element in "type"
79 *  type - the data type that contains "member"
80 *  member - the list_head element in "type"
81 */
82#define list_entry(ptr, type, member) \
83	((type *)((uintptr_t)(ptr) - (uintptr_t)offsetof(type, member)))
84
85/* Get each entry from a list
86 *  pos - A structure pointer has a "member" element
87 *  head - list head
88 *  member - the list_head element in "pos"
89 *  type - the type of the first parameter
90 */
91#define list_for_each_entry(pos, head, member, type)			\
92	for (pos = list_entry((head)->next, type, member);			\
93		 &pos->member != (head);								\
94		 pos = list_entry(pos->member.next, type, member))
95
96#define list_for_each_entry_safe(pos, n, head, member, type)	\
97	for (pos = list_entry((head)->next, type, member),			\
98		 n = list_entry(pos->member.next, type, member);		\
99		 &pos->member != (head);								\
100		 pos = n, n = list_entry(n->member.next, type, member))
101
102#define list_empty(entry) ((entry)->next == (entry))
103
104static inline void list_init(struct list_head *entry)
105{
106	entry->prev = entry->next = entry;
107}
108
109static inline void list_add(struct list_head *entry, struct list_head *head)
110{
111	entry->next = head->next;
112	entry->prev = head;
113
114	head->next->prev = entry;
115	head->next = entry;
116}
117
118static inline void list_add_tail(struct list_head *entry,
119	struct list_head *head)
120{
121	entry->next = head;
122	entry->prev = head->prev;
123
124	head->prev->next = entry;
125	head->prev = entry;
126}
127
128static inline void list_del(struct list_head *entry)
129{
130	entry->next->prev = entry->prev;
131	entry->prev->next = entry->next;
132	entry->next = entry->prev = NULL;
133}
134
135static inline void *usbi_reallocf(void *ptr, size_t size)
136{
137	void *ret = realloc(ptr, size);
138	if (!ret)
139		free(ptr);
140	return ret;
141}
142
143#define container_of(ptr, type, member) ({                      \
144        const typeof( ((type *)0)->member ) *mptr = (ptr);    \
145        (type *)( (char *)mptr - offsetof(type,member) );})
146
147#define MIN(a, b)	((a) < (b) ? (a) : (b))
148#define MAX(a, b)	((a) > (b) ? (a) : (b))
149
150#define TIMESPEC_IS_SET(ts) ((ts)->tv_sec != 0 || (ts)->tv_nsec != 0)
151
152void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
153	const char *function, const char *format, ...);
154
155void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
156	const char *function, const char *format, va_list args);
157
158#if !defined(_MSC_VER) || _MSC_VER >= 1400
159
160#ifdef ENABLE_LOGGING
161#define _usbi_log(ctx, level, ...) usbi_log(ctx, level, __FUNCTION__, __VA_ARGS__)
162#define usbi_dbg(...) _usbi_log(NULL, LIBUSB_LOG_LEVEL_DEBUG, __VA_ARGS__)
163#else
164#define _usbi_log(ctx, level, ...) do { (void)(ctx); } while(0)
165#define usbi_dbg(...) do {} while(0)
166#endif
167
168#define usbi_info(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_INFO, __VA_ARGS__)
169#define usbi_warn(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_WARNING, __VA_ARGS__)
170#define usbi_err(ctx, ...) _usbi_log(ctx, LIBUSB_LOG_LEVEL_ERROR, __VA_ARGS__)
171
172#else /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
173
174#ifdef ENABLE_LOGGING
175#define LOG_BODY(ctxt, level) \
176{                             \
177	va_list args;             \
178	va_start (args, format);  \
179	usbi_log_v(ctxt, level, "", format, args); \
180	va_end(args);             \
181}
182#else
183#define LOG_BODY(ctxt, level) do { (void)(ctxt); } while(0)
184#endif
185
186static inline void usbi_info(struct libusb_context *ctx, const char *format,
187	...)
188	LOG_BODY(ctx,LIBUSB_LOG_LEVEL_INFO)
189static inline void usbi_warn(struct libusb_context *ctx, const char *format,
190	...)
191	LOG_BODY(ctx,LIBUSB_LOG_LEVEL_WARNING)
192static inline void usbi_err( struct libusb_context *ctx, const char *format,
193	...)
194	LOG_BODY(ctx,LIBUSB_LOG_LEVEL_ERROR)
195
196static inline void usbi_dbg(const char *format, ...)
197	LOG_BODY(NULL,LIBUSB_LOG_LEVEL_DEBUG)
198
199#endif /* !defined(_MSC_VER) || _MSC_VER >= 1400 */
200
201#define USBI_GET_CONTEXT(ctx) if (!(ctx)) (ctx) = usbi_default_context
202#define DEVICE_CTX(dev) ((dev)->ctx)
203#define HANDLE_CTX(handle) (DEVICE_CTX((handle)->dev))
204#define TRANSFER_CTX(transfer) (HANDLE_CTX((transfer)->dev_handle))
205#define ITRANSFER_CTX(transfer) \
206	(TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer)))
207
208#define IS_EPIN(ep) (0 != ((ep) & LIBUSB_ENDPOINT_IN))
209#define IS_EPOUT(ep) (!IS_EPIN(ep))
210#define IS_XFERIN(xfer) (0 != ((xfer)->endpoint & LIBUSB_ENDPOINT_IN))
211#define IS_XFEROUT(xfer) (!IS_XFERIN(xfer))
212
213/* Internal abstraction for thread synchronization */
214#if defined(THREADS_POSIX)
215#include "os/threads_posix.h"
216#elif defined(OS_WINDOWS) || defined(OS_WINCE)
217#include <os/threads_windows.h>
218#endif
219
220extern struct libusb_context *usbi_default_context;
221
222struct libusb_context {
223	int debug;
224	int debug_fixed;
225
226	/* internal control pipe, used for interrupting event handling when
227	 * something needs to modify poll fds. */
228	int ctrl_pipe[2];
229
230	struct list_head usb_devs;
231	usbi_mutex_t usb_devs_lock;
232
233	/* A list of open handles. Backends are free to traverse this if required.
234	 */
235	struct list_head open_devs;
236	usbi_mutex_t open_devs_lock;
237
238	/* A list of registered hotplug callbacks */
239	struct list_head hotplug_cbs;
240	usbi_mutex_t hotplug_cbs_lock;
241	int hotplug_pipe[2];
242
243	/* this is a list of in-flight transfer handles, sorted by timeout
244	 * expiration. URBs to timeout the soonest are placed at the beginning of
245	 * the list, URBs that will time out later are placed after, and urbs with
246	 * infinite timeout are always placed at the very end. */
247	struct list_head flying_transfers;
248	usbi_mutex_t flying_transfers_lock;
249
250	/* list of poll fds */
251	struct list_head pollfds;
252	usbi_mutex_t pollfds_lock;
253
254	/* a counter that is set when we want to interrupt event handling, in order
255	 * to modify the poll fd set. and a lock to protect it. */
256	unsigned int pollfd_modify;
257	usbi_mutex_t pollfd_modify_lock;
258
259	/* user callbacks for pollfd changes */
260	libusb_pollfd_added_cb fd_added_cb;
261	libusb_pollfd_removed_cb fd_removed_cb;
262	void *fd_cb_user_data;
263
264	/* ensures that only one thread is handling events at any one time */
265	usbi_mutex_t events_lock;
266
267	/* used to see if there is an active thread doing event handling */
268	int event_handler_active;
269
270	/* used to wait for event completion in threads other than the one that is
271	 * event handling */
272	usbi_mutex_t event_waiters_lock;
273	usbi_cond_t event_waiters_cond;
274
275#ifdef USBI_TIMERFD_AVAILABLE
276	/* used for timeout handling, if supported by OS.
277	 * this timerfd is maintained to trigger on the next pending timeout */
278	int timerfd;
279#endif
280
281	struct list_head list;
282};
283
284#ifdef USBI_TIMERFD_AVAILABLE
285#define usbi_using_timerfd(ctx) ((ctx)->timerfd >= 0)
286#else
287#define usbi_using_timerfd(ctx) (0)
288#endif
289
290struct libusb_device {
291	/* lock protects refcnt, everything else is finalized at initialization
292	 * time */
293	usbi_mutex_t lock;
294	int refcnt;
295
296	struct libusb_context *ctx;
297
298	uint8_t bus_number;
299	uint8_t port_number;
300	struct libusb_device* parent_dev;
301	uint8_t device_address;
302	uint8_t num_configurations;
303	enum libusb_speed speed;
304
305	struct list_head list;
306	unsigned long session_data;
307
308	struct libusb_device_descriptor device_descriptor;
309	int attached;
310
311	unsigned char os_priv
312#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
313	[] /* valid C99 code */
314#else
315	[0] /* non-standard, but usually working code */
316#endif
317	;
318};
319
320struct libusb_device_handle {
321	/* lock protects claimed_interfaces */
322	usbi_mutex_t lock;
323	unsigned long claimed_interfaces;
324
325	struct list_head list;
326	struct libusb_device *dev;
327	int auto_detach_kernel_driver;
328	unsigned char os_priv
329#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
330	[] /* valid C99 code */
331#else
332	[0] /* non-standard, but usually working code */
333#endif
334	;
335};
336
337enum {
338  USBI_CLOCK_MONOTONIC,
339  USBI_CLOCK_REALTIME
340};
341
342/* in-memory transfer layout:
343 *
344 * 1. struct usbi_transfer
345 * 2. struct libusb_transfer (which includes iso packets) [variable size]
346 * 3. os private data [variable size]
347 *
348 * from a libusb_transfer, you can get the usbi_transfer by rewinding the
349 * appropriate number of bytes.
350 * the usbi_transfer includes the number of allocated packets, so you can
351 * determine the size of the transfer and hence the start and length of the
352 * OS-private data.
353 */
354
355struct usbi_transfer {
356	int num_iso_packets;
357	struct list_head list;
358	struct timeval timeout;
359	int transferred;
360	uint8_t flags;
361
362	/* this lock is held during libusb_submit_transfer() and
363	 * libusb_cancel_transfer() (allowing the OS backend to prevent duplicate
364	 * cancellation, submission-during-cancellation, etc). the OS backend
365	 * should also take this lock in the handle_events path, to prevent the user
366	 * cancelling the transfer from another thread while you are processing
367	 * its completion (presumably there would be races within your OS backend
368	 * if this were possible). */
369	usbi_mutex_t lock;
370};
371
372enum usbi_transfer_flags {
373	/* The transfer has timed out */
374	USBI_TRANSFER_TIMED_OUT = 1 << 0,
375
376	/* Set by backend submit_transfer() if the OS handles timeout */
377	USBI_TRANSFER_OS_HANDLES_TIMEOUT = 1 << 1,
378
379	/* Cancellation was requested via libusb_cancel_transfer() */
380	USBI_TRANSFER_CANCELLING = 1 << 2,
381
382	/* Operation on the transfer failed because the device disappeared */
383	USBI_TRANSFER_DEVICE_DISAPPEARED = 1 << 3,
384
385	/* Set by backend submit_transfer() if the fds in use have been updated */
386	USBI_TRANSFER_UPDATED_FDS = 1 << 4,
387};
388
389#define USBI_TRANSFER_TO_LIBUSB_TRANSFER(transfer) \
390	((struct libusb_transfer *)(((unsigned char *)(transfer)) \
391		+ sizeof(struct usbi_transfer)))
392#define LIBUSB_TRANSFER_TO_USBI_TRANSFER(transfer) \
393	((struct usbi_transfer *)(((unsigned char *)(transfer)) \
394		- sizeof(struct usbi_transfer)))
395
396static inline void *usbi_transfer_get_os_priv(struct usbi_transfer *transfer)
397{
398	return ((unsigned char *)transfer) + sizeof(struct usbi_transfer)
399		+ sizeof(struct libusb_transfer)
400		+ (transfer->num_iso_packets
401			* sizeof(struct libusb_iso_packet_descriptor));
402}
403
404/* bus structures */
405
406/* All standard descriptors have these 2 fields in common */
407struct usb_descriptor_header {
408	uint8_t  bLength;
409	uint8_t  bDescriptorType;
410};
411
412/* shared data and functions */
413
414int usbi_io_init(struct libusb_context *ctx);
415void usbi_io_exit(struct libusb_context *ctx);
416
417struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
418	unsigned long session_id);
419struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
420	unsigned long session_id);
421int usbi_sanitize_device(struct libusb_device *dev);
422void usbi_handle_disconnect(struct libusb_device_handle *handle);
423
424int usbi_handle_transfer_completion(struct usbi_transfer *itransfer,
425	enum libusb_transfer_status status);
426int usbi_handle_transfer_cancellation(struct usbi_transfer *transfer);
427
428int usbi_parse_descriptor(const unsigned char *source, const char *descriptor,
429	void *dest, int host_endian);
430int usbi_device_cache_descriptor(libusb_device *dev);
431int usbi_get_config_index_by_value(struct libusb_device *dev,
432	uint8_t bConfigurationValue, int *idx);
433
434void usbi_connect_device (struct libusb_device *dev);
435void usbi_disconnect_device (struct libusb_device *dev);
436
437/* Internal abstraction for poll (needs struct usbi_transfer on Windows) */
438#if defined(OS_LINUX) || defined(OS_DARWIN) || defined(OS_OPENBSD) || defined(OS_NETBSD)
439#include <unistd.h>
440#include "os/poll_posix.h"
441#elif defined(OS_WINDOWS) || defined(OS_WINCE)
442#include "os/poll_windows.h"
443#endif
444
445#if (defined(OS_WINDOWS) || defined(OS_WINCE)) && !defined(__GNUC__)
446#define snprintf _snprintf
447#define vsnprintf _vsnprintf
448int usbi_gettimeofday(struct timeval *tp, void *tzp);
449#define LIBUSB_GETTIMEOFDAY_WIN32
450#define HAVE_USBI_GETTIMEOFDAY
451#else
452#ifdef HAVE_GETTIMEOFDAY
453#define usbi_gettimeofday(tv, tz) gettimeofday((tv), (tz))
454#define HAVE_USBI_GETTIMEOFDAY
455#endif
456#endif
457
458struct usbi_pollfd {
459	/* must come first */
460	struct libusb_pollfd pollfd;
461
462	struct list_head list;
463};
464
465int usbi_add_pollfd(struct libusb_context *ctx, int fd, short events);
466void usbi_remove_pollfd(struct libusb_context *ctx, int fd);
467void usbi_fd_notification(struct libusb_context *ctx);
468
469/* device discovery */
470
471/* we traverse usbfs without knowing how many devices we are going to find.
472 * so we create this discovered_devs model which is similar to a linked-list
473 * which grows when required. it can be freed once discovery has completed,
474 * eliminating the need for a list node in the libusb_device structure
475 * itself. */
476struct discovered_devs {
477	size_t len;
478	size_t capacity;
479	struct libusb_device *devices
480#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
481	[] /* valid C99 code */
482#else
483	[0] /* non-standard, but usually working code */
484#endif
485	;
486};
487
488struct discovered_devs *discovered_devs_append(
489	struct discovered_devs *discdevs, struct libusb_device *dev);
490
491/* OS abstraction */
492
493/* This is the interface that OS backends need to implement.
494 * All fields are mandatory, except ones explicitly noted as optional. */
495struct usbi_os_backend {
496	/* A human-readable name for your backend, e.g. "Linux usbfs" */
497	const char *name;
498
499	/* Binary mask for backend specific capabilities */
500	uint32_t caps;
501
502	/* Perform initialization of your backend. You might use this function
503	 * to determine specific capabilities of the system, allocate required
504	 * data structures for later, etc.
505	 *
506	 * This function is called when a libusbx user initializes the library
507	 * prior to use.
508	 *
509	 * Return 0 on success, or a LIBUSB_ERROR code on failure.
510	 */
511	int (*init)(struct libusb_context *ctx);
512
513	/* Deinitialization. Optional. This function should destroy anything
514	 * that was set up by init.
515	 *
516	 * This function is called when the user deinitializes the library.
517	 */
518	void (*exit)(void);
519
520	/* Enumerate all the USB devices on the system, returning them in a list
521	 * of discovered devices.
522	 *
523	 * Your implementation should enumerate all devices on the system,
524	 * regardless of whether they have been seen before or not.
525	 *
526	 * When you have found a device, compute a session ID for it. The session
527	 * ID should uniquely represent that particular device for that particular
528	 * connection session since boot (i.e. if you disconnect and reconnect a
529	 * device immediately after, it should be assigned a different session ID).
530	 * If your OS cannot provide a unique session ID as described above,
531	 * presenting a session ID of (bus_number << 8 | device_address) should
532	 * be sufficient. Bus numbers and device addresses wrap and get reused,
533	 * but that is an unlikely case.
534	 *
535	 * After computing a session ID for a device, call
536	 * usbi_get_device_by_session_id(). This function checks if libusbx already
537	 * knows about the device, and if so, it provides you with a libusb_device
538	 * structure for it.
539	 *
540	 * If usbi_get_device_by_session_id() returns NULL, it is time to allocate
541	 * a new device structure for the device. Call usbi_alloc_device() to
542	 * obtain a new libusb_device structure with reference count 1. Populate
543	 * the bus_number and device_address attributes of the new device, and
544	 * perform any other internal backend initialization you need to do. At
545	 * this point, you should be ready to provide device descriptors and so
546	 * on through the get_*_descriptor functions. Finally, call
547	 * usbi_sanitize_device() to perform some final sanity checks on the
548	 * device. Assuming all of the above succeeded, we can now continue.
549	 * If any of the above failed, remember to unreference the device that
550	 * was returned by usbi_alloc_device().
551	 *
552	 * At this stage we have a populated libusb_device structure (either one
553	 * that was found earlier, or one that we have just allocated and
554	 * populated). This can now be added to the discovered devices list
555	 * using discovered_devs_append(). Note that discovered_devs_append()
556	 * may reallocate the list, returning a new location for it, and also
557	 * note that reallocation can fail. Your backend should handle these
558	 * error conditions appropriately.
559	 *
560	 * This function should not generate any bus I/O and should not block.
561	 * If I/O is required (e.g. reading the active configuration value), it is
562	 * OK to ignore these suggestions :)
563	 *
564	 * This function is executed when the user wishes to retrieve a list
565	 * of USB devices connected to the system.
566	 *
567	 * If the backend has hotplug support, this function is not used!
568	 *
569	 * Return 0 on success, or a LIBUSB_ERROR code on failure.
570	 */
571	int (*get_device_list)(struct libusb_context *ctx,
572		struct discovered_devs **discdevs);
573
574	/* Apps which were written before hotplug support, may listen for
575	 * hotplug events on their own and call libusb_get_device_list on
576	 * device addition. In this case libusb_get_device_list will likely
577	 * return a list without the new device in there, as the hotplug
578	 * event thread will still be busy enumerating the device, which may
579	 * take a while, or may not even have seen the event yet.
580	 *
581	 * To avoid this libusb_get_device_list will call this optional
582	 * function for backends with hotplug support before copying
583	 * ctx->usb_devs to the user. In this function the backend should
584	 * ensure any pending hotplug events are fully processed before
585	 * returning.
586	 *
587	 * Optional, should be implemented by backends with hotplug support.
588	 */
589	void (*hotplug_poll)(void);
590
591	/* Open a device for I/O and other USB operations. The device handle
592	 * is preallocated for you, you can retrieve the device in question
593	 * through handle->dev.
594	 *
595	 * Your backend should allocate any internal resources required for I/O
596	 * and other operations so that those operations can happen (hopefully)
597	 * without hiccup. This is also a good place to inform libusbx that it
598	 * should monitor certain file descriptors related to this device -
599	 * see the usbi_add_pollfd() function.
600	 *
601	 * This function should not generate any bus I/O and should not block.
602	 *
603	 * This function is called when the user attempts to obtain a device
604	 * handle for a device.
605	 *
606	 * Return:
607	 * - 0 on success
608	 * - LIBUSB_ERROR_ACCESS if the user has insufficient permissions
609	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since
610	 *   discovery
611	 * - another LIBUSB_ERROR code on other failure
612	 *
613	 * Do not worry about freeing the handle on failed open, the upper layers
614	 * do this for you.
615	 */
616	int (*open)(struct libusb_device_handle *handle);
617
618	/* Close a device such that the handle cannot be used again. Your backend
619	 * should destroy any resources that were allocated in the open path.
620	 * This may also be a good place to call usbi_remove_pollfd() to inform
621	 * libusbx of any file descriptors associated with this device that should
622	 * no longer be monitored.
623	 *
624	 * This function is called when the user closes a device handle.
625	 */
626	void (*close)(struct libusb_device_handle *handle);
627
628	/* Retrieve the device descriptor from a device.
629	 *
630	 * The descriptor should be retrieved from memory, NOT via bus I/O to the
631	 * device. This means that you may have to cache it in a private structure
632	 * during get_device_list enumeration. Alternatively, you may be able
633	 * to retrieve it from a kernel interface (some Linux setups can do this)
634	 * still without generating bus I/O.
635	 *
636	 * This function is expected to write DEVICE_DESC_LENGTH (18) bytes into
637	 * buffer, which is guaranteed to be big enough.
638	 *
639	 * This function is called when sanity-checking a device before adding
640	 * it to the list of discovered devices, and also when the user requests
641	 * to read the device descriptor.
642	 *
643	 * This function is expected to return the descriptor in bus-endian format
644	 * (LE). If it returns the multi-byte values in host-endian format,
645	 * set the host_endian output parameter to "1".
646	 *
647	 * Return 0 on success or a LIBUSB_ERROR code on failure.
648	 */
649	int (*get_device_descriptor)(struct libusb_device *device,
650		unsigned char *buffer, int *host_endian);
651
652	/* Get the ACTIVE configuration descriptor for a device.
653	 *
654	 * The descriptor should be retrieved from memory, NOT via bus I/O to the
655	 * device. This means that you may have to cache it in a private structure
656	 * during get_device_list enumeration. You may also have to keep track
657	 * of which configuration is active when the user changes it.
658	 *
659	 * This function is expected to write len bytes of data into buffer, which
660	 * is guaranteed to be big enough. If you can only do a partial write,
661	 * return an error code.
662	 *
663	 * This function is expected to return the descriptor in bus-endian format
664	 * (LE). If it returns the multi-byte values in host-endian format,
665	 * set the host_endian output parameter to "1".
666	 *
667	 * Return:
668	 * - 0 on success
669	 * - LIBUSB_ERROR_NOT_FOUND if the device is in unconfigured state
670	 * - another LIBUSB_ERROR code on other failure
671	 */
672	int (*get_active_config_descriptor)(struct libusb_device *device,
673		unsigned char *buffer, size_t len, int *host_endian);
674
675	/* Get a specific configuration descriptor for a device.
676	 *
677	 * The descriptor should be retrieved from memory, NOT via bus I/O to the
678	 * device. This means that you may have to cache it in a private structure
679	 * during get_device_list enumeration.
680	 *
681	 * The requested descriptor is expressed as a zero-based index (i.e. 0
682	 * indicates that we are requesting the first descriptor). The index does
683	 * not (necessarily) equal the bConfigurationValue of the configuration
684	 * being requested.
685	 *
686	 * This function is expected to write len bytes of data into buffer, which
687	 * is guaranteed to be big enough. If you can only do a partial write,
688	 * return an error code.
689	 *
690	 * This function is expected to return the descriptor in bus-endian format
691	 * (LE). If it returns the multi-byte values in host-endian format,
692	 * set the host_endian output parameter to "1".
693	 *
694	 * Return 0 on success or a LIBUSB_ERROR code on failure.
695	 */
696	int (*get_config_descriptor)(struct libusb_device *device,
697		uint8_t config_index, unsigned char *buffer, size_t len,
698		int *host_endian);
699
700	/* Like get_config_descriptor but then by bConfigurationValue instead
701	 * of by index.
702	 *
703	 * Optional, if not present the core will call get_config_descriptor
704	 * for all configs until it finds the desired bConfigurationValue.
705	 *
706	 * Returns a pointer to the raw-descriptor in *buffer, this memory
707	 * is valid as long as device is valid.
708	 *
709	 * Returns the length of the returned raw-descriptor on success,
710	 * or a LIBUSB_ERROR code on failure.
711	 */
712	int (*get_config_descriptor_by_value)(struct libusb_device *device,
713		uint8_t bConfigurationValue, unsigned char **buffer,
714		int *host_endian);
715
716	/* Get the bConfigurationValue for the active configuration for a device.
717	 * Optional. This should only be implemented if you can retrieve it from
718	 * cache (don't generate I/O).
719	 *
720	 * If you cannot retrieve this from cache, either do not implement this
721	 * function, or return LIBUSB_ERROR_NOT_SUPPORTED. This will cause
722	 * libusbx to retrieve the information through a standard control transfer.
723	 *
724	 * This function must be non-blocking.
725	 * Return:
726	 * - 0 on success
727	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
728	 *   was opened
729	 * - LIBUSB_ERROR_NOT_SUPPORTED if the value cannot be retrieved without
730	 *   blocking
731	 * - another LIBUSB_ERROR code on other failure.
732	 */
733	int (*get_configuration)(struct libusb_device_handle *handle, int *config);
734
735	/* Set the active configuration for a device.
736	 *
737	 * A configuration value of -1 should put the device in unconfigured state.
738	 *
739	 * This function can block.
740	 *
741	 * Return:
742	 * - 0 on success
743	 * - LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
744	 * - LIBUSB_ERROR_BUSY if interfaces are currently claimed (and hence
745	 *   configuration cannot be changed)
746	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
747	 *   was opened
748	 * - another LIBUSB_ERROR code on other failure.
749	 */
750	int (*set_configuration)(struct libusb_device_handle *handle, int config);
751
752	/* Claim an interface. When claimed, the application can then perform
753	 * I/O to an interface's endpoints.
754	 *
755	 * This function should not generate any bus I/O and should not block.
756	 * Interface claiming is a logical operation that simply ensures that
757	 * no other drivers/applications are using the interface, and after
758	 * claiming, no other drivers/applicatiosn can use the interface because
759	 * we now "own" it.
760	 *
761	 * Return:
762	 * - 0 on success
763	 * - LIBUSB_ERROR_NOT_FOUND if the interface does not exist
764	 * - LIBUSB_ERROR_BUSY if the interface is in use by another driver/app
765	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
766	 *   was opened
767	 * - another LIBUSB_ERROR code on other failure
768	 */
769	int (*claim_interface)(struct libusb_device_handle *handle, int interface_number);
770
771	/* Release a previously claimed interface.
772	 *
773	 * This function should also generate a SET_INTERFACE control request,
774	 * resetting the alternate setting of that interface to 0. It's OK for
775	 * this function to block as a result.
776	 *
777	 * You will only ever be asked to release an interface which was
778	 * successfully claimed earlier.
779	 *
780	 * Return:
781	 * - 0 on success
782	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
783	 *   was opened
784	 * - another LIBUSB_ERROR code on other failure
785	 */
786	int (*release_interface)(struct libusb_device_handle *handle, int interface_number);
787
788	/* Set the alternate setting for an interface.
789	 *
790	 * You will only ever be asked to set the alternate setting for an
791	 * interface which was successfully claimed earlier.
792	 *
793	 * It's OK for this function to block.
794	 *
795	 * Return:
796	 * - 0 on success
797	 * - LIBUSB_ERROR_NOT_FOUND if the alternate setting does not exist
798	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
799	 *   was opened
800	 * - another LIBUSB_ERROR code on other failure
801	 */
802	int (*set_interface_altsetting)(struct libusb_device_handle *handle,
803		int interface_number, int altsetting);
804
805	/* Clear a halt/stall condition on an endpoint.
806	 *
807	 * It's OK for this function to block.
808	 *
809	 * Return:
810	 * - 0 on success
811	 * - LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
812	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
813	 *   was opened
814	 * - another LIBUSB_ERROR code on other failure
815	 */
816	int (*clear_halt)(struct libusb_device_handle *handle,
817		unsigned char endpoint);
818
819	/* Perform a USB port reset to reinitialize a device.
820	 *
821	 * If possible, the handle should still be usable after the reset
822	 * completes, assuming that the device descriptors did not change during
823	 * reset and all previous interface state can be restored.
824	 *
825	 * If something changes, or you cannot easily locate/verify the resetted
826	 * device, return LIBUSB_ERROR_NOT_FOUND. This prompts the application
827	 * to close the old handle and re-enumerate the device.
828	 *
829	 * Return:
830	 * - 0 on success
831	 * - LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the device
832	 *   has been disconnected since it was opened
833	 * - another LIBUSB_ERROR code on other failure
834	 */
835	int (*reset_device)(struct libusb_device_handle *handle);
836
837	/* Determine if a kernel driver is active on an interface. Optional.
838	 *
839	 * The presence of a kernel driver on an interface indicates that any
840	 * calls to claim_interface would fail with the LIBUSB_ERROR_BUSY code.
841	 *
842	 * Return:
843	 * - 0 if no driver is active
844	 * - 1 if a driver is active
845	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
846	 *   was opened
847	 * - another LIBUSB_ERROR code on other failure
848	 */
849	int (*kernel_driver_active)(struct libusb_device_handle *handle,
850		int interface_number);
851
852	/* Detach a kernel driver from an interface. Optional.
853	 *
854	 * After detaching a kernel driver, the interface should be available
855	 * for claim.
856	 *
857	 * Return:
858	 * - 0 on success
859	 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
860	 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
861	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
862	 *   was opened
863	 * - another LIBUSB_ERROR code on other failure
864	 */
865	int (*detach_kernel_driver)(struct libusb_device_handle *handle,
866		int interface_number);
867
868	/* Attach a kernel driver to an interface. Optional.
869	 *
870	 * Reattach a kernel driver to the device.
871	 *
872	 * Return:
873	 * - 0 on success
874	 * - LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
875	 * - LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
876	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected since it
877	 *   was opened
878	 * - LIBUSB_ERROR_BUSY if a program or driver has claimed the interface,
879	 *   preventing reattachment
880	 * - another LIBUSB_ERROR code on other failure
881	 */
882	int (*attach_kernel_driver)(struct libusb_device_handle *handle,
883		int interface_number);
884
885	/* Destroy a device. Optional.
886	 *
887	 * This function is called when the last reference to a device is
888	 * destroyed. It should free any resources allocated in the get_device_list
889	 * path.
890	 */
891	void (*destroy_device)(struct libusb_device *dev);
892
893	/* Submit a transfer. Your implementation should take the transfer,
894	 * morph it into whatever form your platform requires, and submit it
895	 * asynchronously.
896	 *
897	 * This function must not block.
898	 *
899	 * This function gets called with the flying_transfers_lock locked!
900	 *
901	 * Return:
902	 * - 0 on success
903	 * - LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
904	 * - another LIBUSB_ERROR code on other failure
905	 */
906	int (*submit_transfer)(struct usbi_transfer *itransfer);
907
908	/* Cancel a previously submitted transfer.
909	 *
910	 * This function must not block. The transfer cancellation must complete
911	 * later, resulting in a call to usbi_handle_transfer_cancellation()
912	 * from the context of handle_events.
913	 */
914	int (*cancel_transfer)(struct usbi_transfer *itransfer);
915
916	/* Clear a transfer as if it has completed or cancelled, but do not
917	 * report any completion/cancellation to the library. You should free
918	 * all private data from the transfer as if you were just about to report
919	 * completion or cancellation.
920	 *
921	 * This function might seem a bit out of place. It is used when libusbx
922	 * detects a disconnected device - it calls this function for all pending
923	 * transfers before reporting completion (with the disconnect code) to
924	 * the user. Maybe we can improve upon this internal interface in future.
925	 */
926	void (*clear_transfer_priv)(struct usbi_transfer *itransfer);
927
928	/* Handle any pending events. This involves monitoring any active
929	 * transfers and processing their completion or cancellation.
930	 *
931	 * The function is passed an array of pollfd structures (size nfds)
932	 * as a result of the poll() system call. The num_ready parameter
933	 * indicates the number of file descriptors that have reported events
934	 * (i.e. the poll() return value). This should be enough information
935	 * for you to determine which actions need to be taken on the currently
936	 * active transfers.
937	 *
938	 * For any cancelled transfers, call usbi_handle_transfer_cancellation().
939	 * For completed transfers, call usbi_handle_transfer_completion().
940	 * For control/bulk/interrupt transfers, populate the "transferred"
941	 * element of the appropriate usbi_transfer structure before calling the
942	 * above functions. For isochronous transfers, populate the status and
943	 * transferred fields of the iso packet descriptors of the transfer.
944	 *
945	 * This function should also be able to detect disconnection of the
946	 * device, reporting that situation with usbi_handle_disconnect().
947	 *
948	 * When processing an event related to a transfer, you probably want to
949	 * take usbi_transfer.lock to prevent races. See the documentation for
950	 * the usbi_transfer structure.
951	 *
952	 * Return 0 on success, or a LIBUSB_ERROR code on failure.
953	 */
954	int (*handle_events)(struct libusb_context *ctx,
955		struct pollfd *fds, POLL_NFDS_TYPE nfds, int num_ready);
956
957	/* Get time from specified clock. At least two clocks must be implemented
958	   by the backend: USBI_CLOCK_REALTIME, and USBI_CLOCK_MONOTONIC.
959
960	   Description of clocks:
961	     USBI_CLOCK_REALTIME : clock returns time since system epoch.
962	     USBI_CLOCK_MONOTONIC: clock returns time since unspecified start
963	                             time (usually boot).
964	 */
965	int (*clock_gettime)(int clkid, struct timespec *tp);
966
967#ifdef USBI_TIMERFD_AVAILABLE
968	/* clock ID of the clock that should be used for timerfd */
969	clockid_t (*get_timerfd_clockid)(void);
970#endif
971
972	/* Number of bytes to reserve for per-device private backend data.
973	 * This private data area is accessible through the "os_priv" field of
974	 * struct libusb_device. */
975	size_t device_priv_size;
976
977	/* Number of bytes to reserve for per-handle private backend data.
978	 * This private data area is accessible through the "os_priv" field of
979	 * struct libusb_device. */
980	size_t device_handle_priv_size;
981
982	/* Number of bytes to reserve for per-transfer private backend data.
983	 * This private data area is accessible by calling
984	 * usbi_transfer_get_os_priv() on the appropriate usbi_transfer instance.
985	 */
986	size_t transfer_priv_size;
987
988	/* Mumber of additional bytes for os_priv for each iso packet.
989	 * Can your backend use this? */
990	/* FIXME: linux can't use this any more. if other OS's cannot either,
991	 * then remove this */
992	size_t add_iso_packet_size;
993};
994
995extern const struct usbi_os_backend * const usbi_backend;
996
997extern const struct usbi_os_backend linux_usbfs_backend;
998extern const struct usbi_os_backend darwin_backend;
999extern const struct usbi_os_backend openbsd_backend;
1000extern const struct usbi_os_backend netbsd_backend;
1001extern const struct usbi_os_backend windows_backend;
1002extern const struct usbi_os_backend wince_backend;
1003
1004extern struct list_head active_contexts_list;
1005extern usbi_mutex_static_t active_contexts_lock;
1006
1007#endif
1008