1 /* -*- Mode: C; indent-tabs-mode:t ; c-basic-offset:8 -*- */
3 * Core functions for libusbx
4 * Copyright © 2012-2013 Nathan Hjelm <hjelmn@cs.unm.edu>
5 * Copyright © 2007-2008 Daniel Drake <dsd@gentoo.org>
6 * Copyright © 2001 Johannes Erdfelt <johannes@erdfelt.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
30 #ifdef HAVE_SYS_TYPES_H
31 #include <sys/types.h>
33 #ifdef HAVE_SYS_TIME_H
41 const struct usbi_os_backend * const usbi_backend = &linux_usbfs_backend;
42 #elif defined(OS_DARWIN)
43 const struct usbi_os_backend * const usbi_backend = &darwin_backend;
44 #elif defined(OS_OPENBSD)
45 const struct usbi_os_backend * const usbi_backend = &openbsd_backend;
46 #elif defined(OS_WINDOWS)
47 const struct usbi_os_backend * const usbi_backend = &windows_backend;
48 #elif defined(OS_WINCE)
49 const struct usbi_os_backend * const usbi_backend = &wince_backend;
51 #error "Unsupported OS"
54 struct libusb_context *usbi_default_context = NULL;
55 const struct libusb_version libusb_version_internal =
56 { LIBUSB_MAJOR, LIBUSB_MINOR, LIBUSB_MICRO, LIBUSB_NANO,
57 LIBUSB_RC, "http://libusbx.org" };
58 static int default_context_refcnt = 0;
59 static usbi_mutex_static_t default_context_lock = USBI_MUTEX_INITIALIZER;
60 static struct timeval timestamp_origin = { 0, 0 };
62 usbi_mutex_static_t active_contexts_lock = USBI_MUTEX_INITIALIZER;
63 struct list_head active_contexts_list;
66 * \mainpage libusbx-1.0 API Reference
68 * \section intro Introduction
70 * libusbx is an open source library that allows you to communicate with USB
71 * devices from userspace. For more info, see the
72 * <a href="http://libusbx.org">libusbx homepage</a>.
74 * This documentation is aimed at application developers wishing to
75 * communicate with USB peripherals from their own software. After reviewing
76 * this documentation, feedback and questions can be sent to the
77 * <a href="http://mailing-list.libusbx.org">libusbx-devel mailing list</a>.
79 * This documentation assumes knowledge of how to operate USB devices from
80 * a software standpoint (descriptors, configurations, interfaces, endpoints,
81 * control/bulk/interrupt/isochronous transfers, etc). Full information
82 * can be found in the <a href="http://www.usb.org/developers/docs/">USB 3.0
83 * Specification</a> which is available for free download. You can probably
84 * find less verbose introductions by searching the web.
86 * \section features Library features
88 * - All transfer types supported (control/bulk/interrupt/isochronous)
89 * - 2 transfer interfaces:
90 * -# Synchronous (simple)
91 * -# Asynchronous (more complicated, but more powerful)
92 * - Thread safe (although the asynchronous interface means that you
93 * usually won't need to thread)
94 * - Lightweight with lean API
95 * - Compatible with libusb-0.1 through the libusb-compat-0.1 translation layer
96 * - Hotplug support (see \ref hotplug)
98 * \section gettingstarted Getting Started
100 * To begin reading the API documentation, start with the Modules page which
101 * links to the different categories of libusbx's functionality.
103 * One decision you will have to make is whether to use the synchronous
104 * or the asynchronous data transfer interface. The \ref io documentation
105 * provides some insight into this topic.
107 * Some example programs can be found in the libusbx source distribution under
108 * the "examples" subdirectory. The libusbx homepage includes a list of
109 * real-life project examples which use libusbx.
111 * \section errorhandling Error handling
113 * libusbx functions typically return 0 on success or a negative error code
114 * on failure. These negative error codes relate to LIBUSB_ERROR constants
115 * which are listed on the \ref misc "miscellaneous" documentation page.
117 * \section msglog Debug message logging
119 * libusbx uses stderr for all logging. By default, logging is set to NONE,
120 * which means that no output will be produced. However, unless the library
121 * has been compiled with logging disabled, then any application calls to
122 * libusb_set_debug(), or the setting of the environmental variable
123 * LIBUSB_DEBUG outside of the application, can result in logging being
124 * produced. Your application should therefore not close stderr, but instead
125 * direct it to the null device if its output is undesireable.
127 * The libusb_set_debug() function can be used to enable logging of certain
128 * messages. Under standard configuration, libusbx doesn't really log much
129 * so you are advised to use this function to enable all error/warning/
130 * informational messages. It will help debug problems with your software.
132 * The logged messages are unstructured. There is no one-to-one correspondence
133 * between messages being logged and success or failure return codes from
134 * libusbx functions. There is no format to the messages, so you should not
135 * try to capture or parse them. They are not and will not be localized.
136 * These messages are not intended to being passed to your application user;
137 * instead, you should interpret the error codes returned from libusbx functions
138 * and provide appropriate notification to the user. The messages are simply
139 * there to aid you as a programmer, and if you're confused because you're
140 * getting a strange error code from a libusbx function, enabling message
141 * logging may give you a suitable explanation.
143 * The LIBUSB_DEBUG environment variable can be used to enable message logging
144 * at run-time. This environment variable should be set to a log level number,
145 * which is interpreted the same as the libusb_set_debug() parameter. When this
146 * environment variable is set, the message logging verbosity level is fixed
147 * and libusb_set_debug() effectively does nothing.
149 * libusbx can be compiled without any logging functions, useful for embedded
150 * systems. In this case, libusb_set_debug() and the LIBUSB_DEBUG environment
151 * variable have no effects.
153 * libusbx can also be compiled with verbose debugging messages always. When
154 * the library is compiled in this way, all messages of all verbosities are
155 * always logged. libusb_set_debug() and the LIBUSB_DEBUG environment variable
158 * \section remarks Other remarks
160 * libusbx does have imperfections. The \ref caveats "caveats" page attempts
165 * \page caveats Caveats
167 * \section devresets Device resets
169 * The libusb_reset_device() function allows you to reset a device. If your
170 * program has to call such a function, it should obviously be aware that
171 * the reset will cause device state to change (e.g. register values may be
174 * The problem is that any other program could reset the device your program
175 * is working with, at any time. libusbx does not offer a mechanism to inform
176 * you when this has happened, so if someone else resets your device it will
177 * not be clear to your own program why the device state has changed.
179 * Ultimately, this is a limitation of writing drivers in userspace.
180 * Separation from the USB stack in the underlying kernel makes it difficult
181 * for the operating system to deliver such notifications to your program.
182 * The Linux kernel USB stack allows such reset notifications to be delivered
183 * to in-kernel USB drivers, but it is not clear how such notifications could
184 * be delivered to second-class drivers that live in userspace.
186 * \section blockonly Blocking-only functionality
188 * The functionality listed below is only available through synchronous,
189 * blocking functions. There are no asynchronous/non-blocking alternatives,
190 * and no clear ways of implementing these.
192 * - Configuration activation (libusb_set_configuration())
193 * - Interface/alternate setting activation (libusb_set_interface_alt_setting())
194 * - Releasing of interfaces (libusb_release_interface())
195 * - Clearing of halt/stall condition (libusb_clear_halt())
196 * - Device resets (libusb_reset_device())
198 * \section configsel Configuration selection and handling
200 * When libusbx presents a device handle to an application, there is a chance
201 * that the corresponding device may be in unconfigured state. For devices
202 * with multiple configurations, there is also a chance that the configuration
203 * currently selected is not the one that the application wants to use.
205 * The obvious solution is to add a call to libusb_set_configuration() early
206 * on during your device initialization routines, but there are caveats to
208 * -# If the device is already in the desired configuration, calling
209 * libusb_set_configuration() using the same configuration value will cause
210 * a lightweight device reset. This may not be desirable behaviour.
211 * -# libusbx will be unable to change configuration if the device is in
212 * another configuration and other programs or drivers have claimed
213 * interfaces under that configuration.
214 * -# In the case where the desired configuration is already active, libusbx
215 * may not even be able to perform a lightweight device reset. For example,
216 * take my USB keyboard with fingerprint reader: I'm interested in driving
217 * the fingerprint reader interface through libusbx, but the kernel's
218 * USB-HID driver will almost always have claimed the keyboard interface.
219 * Because the kernel has claimed an interface, it is not even possible to
220 * perform the lightweight device reset, so libusb_set_configuration() will
221 * fail. (Luckily the device in question only has a single configuration.)
223 * One solution to some of the above problems is to consider the currently
224 * active configuration. If the configuration we want is already active, then
225 * we don't have to select any configuration:
227 cfg = libusb_get_configuration(dev);
229 libusb_set_configuration(dev, desired);
232 * This is probably suitable for most scenarios, but is inherently racy:
233 * another application or driver may change the selected configuration
234 * <em>after</em> the libusb_get_configuration() call.
236 * Even in cases where libusb_set_configuration() succeeds, consider that other
237 * applications or drivers may change configuration after your application
238 * calls libusb_set_configuration().
240 * One possible way to lock your device into a specific configuration is as
242 * -# Set the desired configuration (or use the logic above to realise that
243 * it is already in the desired configuration)
244 * -# Claim the interface that you wish to use
245 * -# Check that the currently active configuration is the one that you want
248 * The above method works because once an interface is claimed, no application
249 * or driver is able to select another configuration.
251 * \section earlycomp Early transfer completion
253 * NOTE: This section is currently Linux-centric. I am not sure if any of these
254 * considerations apply to Darwin or other platforms.
256 * When a transfer completes early (i.e. when less data is received/sent in
257 * any one packet than the transfer buffer allows for) then libusbx is designed
258 * to terminate the transfer immediately, not transferring or receiving any
259 * more data unless other transfers have been queued by the user.
261 * On legacy platforms, libusbx is unable to do this in all situations. After
262 * the incomplete packet occurs, "surplus" data may be transferred. For recent
263 * versions of libusbx, this information is kept (the data length of the
264 * transfer is updated) and, for device-to-host transfers, any surplus data was
265 * added to the buffer. Still, this is not a nice solution because it loses the
266 * information about the end of the short packet, and the user probably wanted
267 * that surplus data to arrive in the next logical transfer.
270 * \section zlp Zero length packets
272 * - libusbx is able to send a packet of zero length to an endpoint simply by
273 * submitting a transfer of zero length.
274 * - The \ref libusb_transfer_flags::LIBUSB_TRANSFER_ADD_ZERO_PACKET
275 * "LIBUSB_TRANSFER_ADD_ZERO_PACKET" flag is currently only supported on Linux.
279 * \page contexts Contexts
281 * It is possible that libusbx may be used simultaneously from two independent
282 * libraries linked into the same executable. For example, if your application
283 * has a plugin-like system which allows the user to dynamically load a range
284 * of modules into your program, it is feasible that two independently
285 * developed modules may both use libusbx.
287 * libusbx is written to allow for these multiple user scenarios. The two
288 * "instances" of libusbx will not interfere: libusb_set_debug() calls
289 * from one user will not affect the same settings for other users, other
290 * users can continue using libusbx after one of them calls libusb_exit(), etc.
292 * This is made possible through libusbx's <em>context</em> concept. When you
293 * call libusb_init(), you are (optionally) given a context. You can then pass
294 * this context pointer back into future libusbx functions.
296 * In order to keep things simple for more simplistic applications, it is
297 * legal to pass NULL to all functions requiring a context pointer (as long as
298 * you're sure no other code will attempt to use libusbx from the same process).
299 * When you pass NULL, the default context will be used. The default context
300 * is created the first time a process calls libusb_init() when no other
301 * context is alive. Contexts are destroyed during libusb_exit().
303 * The default context is reference-counted and can be shared. That means that
304 * if libusb_init(NULL) is called twice within the same process, the two
305 * users end up sharing the same context. The deinitialization and freeing of
306 * the default context will only happen when the last user calls libusb_exit().
307 * In other words, the default context is created and initialized when its
308 * reference count goes from 0 to 1, and is deinitialized and destroyed when
309 * its reference count goes from 1 to 0.
311 * You may be wondering why only a subset of libusbx functions require a
312 * context pointer in their function definition. Internally, libusbx stores
313 * context pointers in other objects (e.g. libusb_device instances) and hence
314 * can infer the context from those objects.
318 * @defgroup lib Library initialization/deinitialization
319 * This page details how to initialize and deinitialize libusbx. Initialization
320 * must be performed before using any libusbx functionality, and similarly you
321 * must not call any libusbx functions after deinitialization.
325 * @defgroup dev Device handling and enumeration
326 * The functionality documented below is designed to help with the following
328 * - Enumerating the USB devices currently attached to the system
329 * - Choosing a device to operate from your software
330 * - Opening and closing the chosen device
332 * \section nutshell In a nutshell...
334 * The description below really makes things sound more complicated than they
335 * actually are. The following sequence of function calls will be suitable
336 * for almost all scenarios and does not require you to have such a deep
337 * understanding of the resource management issues:
340 libusb_device **list;
341 libusb_device *found = NULL;
342 ssize_t cnt = libusb_get_device_list(NULL, &list);
348 for (i = 0; i < cnt; i++) {
349 libusb_device *device = list[i];
350 if (is_interesting(device)) {
357 libusb_device_handle *handle;
359 err = libusb_open(found, &handle);
365 libusb_free_device_list(list, 1);
368 * The two important points:
369 * - You asked libusb_free_device_list() to unreference the devices (2nd
371 * - You opened the device before freeing the list and unreferencing the
374 * If you ended up with a handle, you can now proceed to perform I/O on the
377 * \section devshandles Devices and device handles
378 * libusbx has a concept of a USB device, represented by the
379 * \ref libusb_device opaque type. A device represents a USB device that
380 * is currently or was previously connected to the system. Using a reference
381 * to a device, you can determine certain information about the device (e.g.
382 * you can read the descriptor data).
384 * The libusb_get_device_list() function can be used to obtain a list of
385 * devices currently connected to the system. This is known as device
388 * Just because you have a reference to a device does not mean it is
389 * necessarily usable. The device may have been unplugged, you may not have
390 * permission to operate such device, or another program or driver may be
393 * When you've found a device that you'd like to operate, you must ask
394 * libusbx to open the device using the libusb_open() function. Assuming
395 * success, libusbx then returns you a <em>device handle</em>
396 * (a \ref libusb_device_handle pointer). All "real" I/O operations then
397 * operate on the handle rather than the original device pointer.
399 * \section devref Device discovery and reference counting
401 * Device discovery (i.e. calling libusb_get_device_list()) returns a
402 * freshly-allocated list of devices. The list itself must be freed when
403 * you are done with it. libusbx also needs to know when it is OK to free
404 * the contents of the list - the devices themselves.
406 * To handle these issues, libusbx provides you with two separate items:
407 * - A function to free the list itself
408 * - A reference counting system for the devices inside
410 * New devices presented by the libusb_get_device_list() function all have a
411 * reference count of 1. You can increase and decrease reference count using
412 * libusb_ref_device() and libusb_unref_device(). A device is destroyed when
413 * its reference count reaches 0.
415 * With the above information in mind, the process of opening a device can
416 * be viewed as follows:
417 * -# Discover devices using libusb_get_device_list().
418 * -# Choose the device that you want to operate, and call libusb_open().
419 * -# Unref all devices in the discovered device list.
420 * -# Free the discovered device list.
422 * The order is important - you must not unreference the device before
423 * attempting to open it, because unreferencing it may destroy the device.
425 * For convenience, the libusb_free_device_list() function includes a
426 * parameter to optionally unreference all the devices in the list before
427 * freeing the list itself. This combines steps 3 and 4 above.
429 * As an implementation detail, libusb_open() actually adds a reference to
430 * the device in question. This is because the device remains available
431 * through the handle via libusb_get_device(). The reference is deleted during
435 /** @defgroup misc Miscellaneous */
437 /* we traverse usbfs without knowing how many devices we are going to find.
438 * so we create this discovered_devs model which is similar to a linked-list
439 * which grows when required. it can be freed once discovery has completed,
440 * eliminating the need for a list node in the libusb_device structure
442 #define DISCOVERED_DEVICES_SIZE_STEP 8
444 static struct discovered_devs *discovered_devs_alloc(void)
446 struct discovered_devs *ret =
447 malloc(sizeof(*ret) + (sizeof(void *) * DISCOVERED_DEVICES_SIZE_STEP));
451 ret->capacity = DISCOVERED_DEVICES_SIZE_STEP;
456 /* append a device to the discovered devices collection. may realloc itself,
457 * returning new discdevs. returns NULL on realloc failure. */
458 struct discovered_devs *discovered_devs_append(
459 struct discovered_devs *discdevs, struct libusb_device *dev)
461 size_t len = discdevs->len;
464 /* if there is space, just append the device */
465 if (len < discdevs->capacity) {
466 discdevs->devices[len] = libusb_ref_device(dev);
471 /* exceeded capacity, need to grow */
472 usbi_dbg("need to increase capacity");
473 capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
474 discdevs = usbi_reallocf(discdevs,
475 sizeof(*discdevs) + (sizeof(void *) * capacity));
477 discdevs->capacity = capacity;
478 discdevs->devices[len] = libusb_ref_device(dev);
485 static void discovered_devs_free(struct discovered_devs *discdevs)
489 for (i = 0; i < discdevs->len; i++)
490 libusb_unref_device(discdevs->devices[i]);
495 /* Allocate a new device with a specific session ID. The returned device has
496 * a reference count of 1. */
497 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
498 unsigned long session_id)
500 size_t priv_size = usbi_backend->device_priv_size;
501 struct libusb_device *dev = calloc(1, sizeof(*dev) + priv_size);
507 r = usbi_mutex_init(&dev->lock, NULL);
515 dev->session_data = session_id;
516 dev->speed = LIBUSB_SPEED_UNKNOWN;
518 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
519 usbi_connect_device (dev);
525 void usbi_connect_device(struct libusb_device *dev)
527 libusb_hotplug_message message;
530 message.event = LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED;
531 message.device = dev;
534 usbi_mutex_lock(&dev->ctx->usb_devs_lock);
535 list_add(&dev->list, &dev->ctx->usb_devs);
536 usbi_mutex_unlock(&dev->ctx->usb_devs_lock);
538 /* Signal that an event has occurred for this device if we support hotplug AND
539 * the hotplug pipe is ready. This prevents an event from getting raised during
540 * initial enumeration. */
541 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG) && dev->ctx->hotplug_pipe[1] > 0) {
542 ret = usbi_write(dev->ctx->hotplug_pipe[1], &message, sizeof(message));
543 if (sizeof (message) != ret) {
544 usbi_err(DEVICE_CTX(dev), "error writing hotplug message");
549 void usbi_disconnect_device(struct libusb_device *dev)
551 libusb_hotplug_message message;
552 struct libusb_context *ctx = dev->ctx;
555 message.event = LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT;
556 message.device = dev;
557 usbi_mutex_lock(&dev->lock);
559 usbi_mutex_unlock(&dev->lock);
561 /* Signal that an event has occurred for this device if we support hotplug AND
562 * the hotplug pipe is ready. This prevents an event from getting raised during
563 * initial enumeration. libusb_handle_events will take care of dereferencing the
565 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG) && dev->ctx->hotplug_pipe[1] > 0) {
566 ret = usbi_write(dev->ctx->hotplug_pipe[1], &message, sizeof(message));
567 if (sizeof(message) != ret) {
568 usbi_err(DEVICE_CTX(dev), "error writing hotplug message");
572 usbi_mutex_lock(&ctx->usb_devs_lock);
573 list_del(&dev->list);
574 usbi_mutex_unlock(&ctx->usb_devs_lock);
577 /* Perform some final sanity checks on a newly discovered device. If this
578 * function fails (negative return code), the device should not be added
579 * to the discovered device list. */
580 int usbi_sanitize_device(struct libusb_device *dev)
583 uint8_t num_configurations;
585 r = usbi_device_cache_descriptor(dev);
589 num_configurations = dev->device_descriptor.bNumConfigurations;
590 if (num_configurations > USB_MAXCONFIG) {
591 usbi_err(DEVICE_CTX(dev), "too many configurations");
592 return LIBUSB_ERROR_IO;
593 } else if (0 == num_configurations)
594 usbi_dbg("zero configurations, maybe an unauthorized device");
596 dev->num_configurations = num_configurations;
600 /* Examine libusbx's internal list of known devices, looking for one with
601 * a specific session ID. Returns the matching device if it was found, and
603 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
604 unsigned long session_id)
606 struct libusb_device *dev;
607 struct libusb_device *ret = NULL;
609 usbi_mutex_lock(&ctx->usb_devs_lock);
610 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device)
611 if (dev->session_data == session_id) {
615 usbi_mutex_unlock(&ctx->usb_devs_lock);
621 * Returns a list of USB devices currently attached to the system. This is
622 * your entry point into finding a USB device to operate.
624 * You are expected to unreference all the devices when you are done with
625 * them, and then free the list with libusb_free_device_list(). Note that
626 * libusb_free_device_list() can unref all the devices for you. Be careful
627 * not to unreference a device you are about to open until after you have
630 * This return value of this function indicates the number of devices in
631 * the resultant list. The list is actually one element larger, as it is
634 * \param ctx the context to operate on, or NULL for the default context
635 * \param list output location for a list of devices. Must be later freed with
636 * libusb_free_device_list().
637 * \returns the number of devices in the outputted list, or any
638 * \ref libusb_error according to errors encountered by the backend.
640 ssize_t API_EXPORTED libusb_get_device_list(libusb_context *ctx,
641 libusb_device ***list)
643 struct discovered_devs *discdevs = discovered_devs_alloc();
644 struct libusb_device **ret;
647 USBI_GET_CONTEXT(ctx);
651 return LIBUSB_ERROR_NO_MEM;
653 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
654 /* backend provides hotplug support */
655 struct libusb_device *dev;
657 if (usbi_backend->hotplug_poll)
658 usbi_backend->hotplug_poll();
660 usbi_mutex_lock(&ctx->usb_devs_lock);
661 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device) {
662 discdevs = discovered_devs_append(discdevs, dev);
665 r = LIBUSB_ERROR_NO_MEM;
669 usbi_mutex_unlock(&ctx->usb_devs_lock);
671 /* backend does not provide hotplug support */
672 r = usbi_backend->get_device_list(ctx, &discdevs);
680 /* convert discovered_devs into a list */
682 ret = calloc(len + 1, sizeof(struct libusb_device *));
684 len = LIBUSB_ERROR_NO_MEM;
689 for (i = 0; i < len; i++) {
690 struct libusb_device *dev = discdevs->devices[i];
691 ret[i] = libusb_ref_device(dev);
696 discovered_devs_free(discdevs);
701 * Frees a list of devices previously discovered using
702 * libusb_get_device_list(). If the unref_devices parameter is set, the
703 * reference count of each device in the list is decremented by 1.
704 * \param list the list to free
705 * \param unref_devices whether to unref the devices in the list
707 void API_EXPORTED libusb_free_device_list(libusb_device **list,
715 struct libusb_device *dev;
717 while ((dev = list[i++]) != NULL)
718 libusb_unref_device(dev);
724 * Get the number of the bus that a device is connected to.
725 * \param dev a device
726 * \returns the bus number
728 uint8_t API_EXPORTED libusb_get_bus_number(libusb_device *dev)
730 return dev->bus_number;
734 * Get the number of the port that a device is connected to
735 * \param dev a device
736 * \returns the port number (0 if not available)
738 uint8_t API_EXPORTED libusb_get_port_number(libusb_device *dev)
740 return dev->port_number;
744 * Get the list of all port numbers from root for the specified device
746 * Since version 1.0.16, \ref LIBUSBX_API_VERSION >= 0x01000102
747 * \param dev a device
748 * \param port_numbers the array that should contain the port numbers
749 * \param port_numbers_len the maximum length of the array. As per the USB 3.0
750 * specs, the current maximum limit for the depth is 7.
751 * \returns the number of elements filled
752 * \returns LIBUSB_ERROR_OVERFLOW if the array is too small
754 int API_EXPORTED libusb_get_port_numbers(libusb_device *dev,
755 uint8_t* port_numbers, int port_numbers_len)
757 int i = port_numbers_len;
760 // HCDs can be listed as devices and would have port #0
761 // TODO: see how the other backends want to implement HCDs as parents
762 if (dev->port_number == 0)
766 usbi_warn(DEVICE_CTX(dev),
767 "port numbers array too small");
768 return LIBUSB_ERROR_OVERFLOW;
770 port_numbers[i] = dev->port_number;
771 dev = dev->parent_dev;
773 memmove(port_numbers, &port_numbers[i], port_numbers_len - i);
774 return port_numbers_len - i;
778 * Deprecated please use libusb_get_port_numbers instead.
780 int API_EXPORTED libusb_get_port_path(libusb_context *ctx, libusb_device *dev,
781 uint8_t* port_numbers, uint8_t port_numbers_len)
785 return libusb_get_port_numbers(dev, port_numbers, port_numbers_len);
789 * Get the the parent from the specified device [EXPERIMENTAL]
790 * \param dev a device
791 * \returns the device parent or NULL if not available
792 * You should issue a libusb_get_device_list() before calling this
793 * function and make sure that you only access the parent before issuing
794 * libusb_free_device_list(). The reason is that libusbx currently does
795 * not maintain a permanent list of device instances, and therefore can
796 * only guarantee that parents are fully instantiated within a
797 * libusb_get_device_list() - libusb_free_device_list() block.
800 libusb_device * LIBUSB_CALL libusb_get_parent(libusb_device *dev)
802 return dev->parent_dev;
806 * Get the address of the device on the bus it is connected to.
807 * \param dev a device
808 * \returns the device address
810 uint8_t API_EXPORTED libusb_get_device_address(libusb_device *dev)
812 return dev->device_address;
816 * Get the negotiated connection speed for a device.
817 * \param dev a device
818 * \returns a \ref libusb_speed code, where LIBUSB_SPEED_UNKNOWN means that
819 * the OS doesn't know or doesn't support returning the negotiated speed.
821 int API_EXPORTED libusb_get_device_speed(libusb_device *dev)
826 static const struct libusb_endpoint_descriptor *find_endpoint(
827 struct libusb_config_descriptor *config, unsigned char endpoint)
830 for (iface_idx = 0; iface_idx < config->bNumInterfaces; iface_idx++) {
831 const struct libusb_interface *iface = &config->interface[iface_idx];
834 for (altsetting_idx = 0; altsetting_idx < iface->num_altsetting;
836 const struct libusb_interface_descriptor *altsetting
837 = &iface->altsetting[altsetting_idx];
840 for (ep_idx = 0; ep_idx < altsetting->bNumEndpoints; ep_idx++) {
841 const struct libusb_endpoint_descriptor *ep =
842 &altsetting->endpoint[ep_idx];
843 if (ep->bEndpointAddress == endpoint)
852 * Convenience function to retrieve the wMaxPacketSize value for a particular
853 * endpoint in the active device configuration.
855 * This function was originally intended to be of assistance when setting up
856 * isochronous transfers, but a design mistake resulted in this function
857 * instead. It simply returns the wMaxPacketSize value without considering
858 * its contents. If you're dealing with isochronous transfers, you probably
859 * want libusb_get_max_iso_packet_size() instead.
861 * \param dev a device
862 * \param endpoint address of the endpoint in question
863 * \returns the wMaxPacketSize value
864 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
865 * \returns LIBUSB_ERROR_OTHER on other failure
867 int API_EXPORTED libusb_get_max_packet_size(libusb_device *dev,
868 unsigned char endpoint)
870 struct libusb_config_descriptor *config;
871 const struct libusb_endpoint_descriptor *ep;
874 r = libusb_get_active_config_descriptor(dev, &config);
876 usbi_err(DEVICE_CTX(dev),
877 "could not retrieve active config descriptor");
878 return LIBUSB_ERROR_OTHER;
881 ep = find_endpoint(config, endpoint);
883 return LIBUSB_ERROR_NOT_FOUND;
885 r = ep->wMaxPacketSize;
886 libusb_free_config_descriptor(config);
891 * Calculate the maximum packet size which a specific endpoint is capable is
892 * sending or receiving in the duration of 1 microframe
894 * Only the active configution is examined. The calculation is based on the
895 * wMaxPacketSize field in the endpoint descriptor as described in section
896 * 9.6.6 in the USB 2.0 specifications.
898 * If acting on an isochronous or interrupt endpoint, this function will
899 * multiply the value found in bits 0:10 by the number of transactions per
900 * microframe (determined by bits 11:12). Otherwise, this function just
901 * returns the numeric value found in bits 0:10.
903 * This function is useful for setting up isochronous transfers, for example
904 * you might pass the return value from this function to
905 * libusb_set_iso_packet_lengths() in order to set the length field of every
906 * isochronous packet in a transfer.
910 * \param dev a device
911 * \param endpoint address of the endpoint in question
912 * \returns the maximum packet size which can be sent/received on this endpoint
913 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
914 * \returns LIBUSB_ERROR_OTHER on other failure
916 int API_EXPORTED libusb_get_max_iso_packet_size(libusb_device *dev,
917 unsigned char endpoint)
919 struct libusb_config_descriptor *config;
920 const struct libusb_endpoint_descriptor *ep;
921 enum libusb_transfer_type ep_type;
925 r = libusb_get_active_config_descriptor(dev, &config);
927 usbi_err(DEVICE_CTX(dev),
928 "could not retrieve active config descriptor");
929 return LIBUSB_ERROR_OTHER;
932 ep = find_endpoint(config, endpoint);
934 return LIBUSB_ERROR_NOT_FOUND;
936 val = ep->wMaxPacketSize;
937 ep_type = (enum libusb_transfer_type) (ep->bmAttributes & 0x3);
938 libusb_free_config_descriptor(config);
941 if (ep_type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
942 || ep_type == LIBUSB_TRANSFER_TYPE_INTERRUPT)
943 r *= (1 + ((val >> 11) & 3));
948 * Increment the reference count of a device.
949 * \param dev the device to reference
950 * \returns the same device
953 libusb_device * LIBUSB_CALL libusb_ref_device(libusb_device *dev)
955 usbi_mutex_lock(&dev->lock);
957 usbi_mutex_unlock(&dev->lock);
962 * Decrement the reference count of a device. If the decrement operation
963 * causes the reference count to reach zero, the device shall be destroyed.
964 * \param dev the device to unreference
966 void API_EXPORTED libusb_unref_device(libusb_device *dev)
973 usbi_mutex_lock(&dev->lock);
974 refcnt = --dev->refcnt;
975 usbi_mutex_unlock(&dev->lock);
978 usbi_dbg("destroy device %d.%d", dev->bus_number, dev->device_address);
980 libusb_unref_device(dev->parent_dev);
982 if (usbi_backend->destroy_device)
983 usbi_backend->destroy_device(dev);
985 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
986 /* backend does not support hotplug */
987 usbi_disconnect_device(dev);
990 usbi_mutex_destroy(&dev->lock);
996 * Interrupt the iteration of the event handling thread, so that it picks
999 void usbi_fd_notification(struct libusb_context *ctx)
1001 unsigned char dummy = 1;
1007 /* record that we are messing with poll fds */
1008 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1009 ctx->pollfd_modify++;
1010 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1012 /* write some data on control pipe to interrupt event handlers */
1013 r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
1015 usbi_warn(ctx, "internal signalling write failed");
1016 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1017 ctx->pollfd_modify--;
1018 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1022 /* take event handling lock */
1023 libusb_lock_events(ctx);
1025 /* read the dummy data */
1026 r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
1028 usbi_warn(ctx, "internal signalling read failed");
1030 /* we're done with modifying poll fds */
1031 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1032 ctx->pollfd_modify--;
1033 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1035 /* Release event handling lock and wake up event waiters */
1036 libusb_unlock_events(ctx);
1040 * Open a device and obtain a device handle. A handle allows you to perform
1041 * I/O on the device in question.
1043 * Internally, this function adds a reference to the device and makes it
1044 * available to you through libusb_get_device(). This reference is removed
1045 * during libusb_close().
1047 * This is a non-blocking function; no requests are sent over the bus.
1049 * \param dev the device to open
1050 * \param handle output location for the returned device handle pointer. Only
1051 * populated when the return code is 0.
1052 * \returns 0 on success
1053 * \returns LIBUSB_ERROR_NO_MEM on memory allocation failure
1054 * \returns LIBUSB_ERROR_ACCESS if the user has insufficient permissions
1055 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1056 * \returns another LIBUSB_ERROR code on other failure
1058 int API_EXPORTED libusb_open(libusb_device *dev,
1059 libusb_device_handle **handle)
1061 struct libusb_context *ctx = DEVICE_CTX(dev);
1062 struct libusb_device_handle *_handle;
1063 size_t priv_size = usbi_backend->device_handle_priv_size;
1065 usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);
1067 if (!dev->attached) {
1068 return LIBUSB_ERROR_NO_DEVICE;
1071 _handle = malloc(sizeof(*_handle) + priv_size);
1073 return LIBUSB_ERROR_NO_MEM;
1075 r = usbi_mutex_init(&_handle->lock, NULL);
1078 return LIBUSB_ERROR_OTHER;
1081 _handle->dev = libusb_ref_device(dev);
1082 _handle->claimed_interfaces = 0;
1083 memset(&_handle->os_priv, 0, priv_size);
1085 r = usbi_backend->open(_handle);
1087 usbi_dbg("open %d.%d returns %d", dev->bus_number, dev->device_address, r);
1088 libusb_unref_device(dev);
1089 usbi_mutex_destroy(&_handle->lock);
1094 usbi_mutex_lock(&ctx->open_devs_lock);
1095 list_add(&_handle->list, &ctx->open_devs);
1096 usbi_mutex_unlock(&ctx->open_devs_lock);
1099 /* At this point, we want to interrupt any existing event handlers so
1100 * that they realise the addition of the new device's poll fd. One
1101 * example when this is desirable is if the user is running a separate
1102 * dedicated libusbx events handling thread, which is running with a long
1103 * or infinite timeout. We want to interrupt that iteration of the loop,
1104 * so that it picks up the new fd, and then continues. */
1105 usbi_fd_notification(ctx);
1111 * Convenience function for finding a device with a particular
1112 * <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
1113 * for those scenarios where you are using libusbx to knock up a quick test
1114 * application - it allows you to avoid calling libusb_get_device_list() and
1115 * worrying about traversing/freeing the list.
1117 * This function has limitations and is hence not intended for use in real
1118 * applications: if multiple devices have the same IDs it will only
1119 * give you the first one, etc.
1121 * \param ctx the context to operate on, or NULL for the default context
1122 * \param vendor_id the idVendor value to search for
1123 * \param product_id the idProduct value to search for
1124 * \returns a handle for the first found device, or NULL on error or if the
1125 * device could not be found. */
1127 libusb_device_handle * LIBUSB_CALL libusb_open_device_with_vid_pid(
1128 libusb_context *ctx, uint16_t vendor_id, uint16_t product_id)
1130 struct libusb_device **devs;
1131 struct libusb_device *found = NULL;
1132 struct libusb_device *dev;
1133 struct libusb_device_handle *handle = NULL;
1137 if (libusb_get_device_list(ctx, &devs) < 0)
1140 while ((dev = devs[i++]) != NULL) {
1141 struct libusb_device_descriptor desc;
1142 r = libusb_get_device_descriptor(dev, &desc);
1145 if (desc.idVendor == vendor_id && desc.idProduct == product_id) {
1152 r = libusb_open(found, &handle);
1158 libusb_free_device_list(devs, 1);
1162 static void do_close(struct libusb_context *ctx,
1163 struct libusb_device_handle *dev_handle)
1165 struct usbi_transfer *itransfer;
1166 struct usbi_transfer *tmp;
1168 libusb_lock_events(ctx);
1170 /* remove any transfers in flight that are for this device */
1171 usbi_mutex_lock(&ctx->flying_transfers_lock);
1173 /* safe iteration because transfers may be being deleted */
1174 list_for_each_entry_safe(itransfer, tmp, &ctx->flying_transfers, list, struct usbi_transfer) {
1175 struct libusb_transfer *transfer =
1176 USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
1178 if (transfer->dev_handle != dev_handle)
1181 if (!(itransfer->flags & USBI_TRANSFER_DEVICE_DISAPPEARED)) {
1182 usbi_err(ctx, "Device handle closed while transfer was still being processed, but the device is still connected as far as we know");
1184 if (itransfer->flags & USBI_TRANSFER_CANCELLING)
1185 usbi_warn(ctx, "A cancellation for an in-flight transfer hasn't completed but closing the device handle");
1187 usbi_err(ctx, "A cancellation hasn't even been scheduled on the transfer for which the device is closing");
1190 /* remove from the list of in-flight transfers and make sure
1191 * we don't accidentally use the device handle in the future
1192 * (or that such accesses will be easily caught and identified as a crash)
1194 usbi_mutex_lock(&itransfer->lock);
1195 list_del(&itransfer->list);
1196 transfer->dev_handle = NULL;
1197 usbi_mutex_unlock(&itransfer->lock);
1199 /* it is up to the user to free up the actual transfer struct. this is
1200 * just making sure that we don't attempt to process the transfer after
1201 * the device handle is invalid
1203 usbi_dbg("Removed transfer %p from the in-flight list because device handle %p closed",
1204 transfer, dev_handle);
1206 usbi_mutex_unlock(&ctx->flying_transfers_lock);
1208 libusb_unlock_events(ctx);
1210 usbi_mutex_lock(&ctx->open_devs_lock);
1211 list_del(&dev_handle->list);
1212 usbi_mutex_unlock(&ctx->open_devs_lock);
1214 usbi_backend->close(dev_handle);
1215 libusb_unref_device(dev_handle->dev);
1216 usbi_mutex_destroy(&dev_handle->lock);
1221 * Close a device handle. Should be called on all open handles before your
1222 * application exits.
1224 * Internally, this function destroys the reference that was added by
1225 * libusb_open() on the given device.
1227 * This is a non-blocking function; no requests are sent over the bus.
1229 * \param dev_handle the handle to close
1231 void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
1233 struct libusb_context *ctx;
1234 unsigned char dummy = 1;
1241 ctx = HANDLE_CTX(dev_handle);
1243 /* Similarly to libusb_open(), we want to interrupt all event handlers
1244 * at this point. More importantly, we want to perform the actual close of
1245 * the device while holding the event handling lock (preventing any other
1246 * thread from doing event handling) because we will be removing a file
1247 * descriptor from the polling loop. */
1249 /* record that we are messing with poll fds */
1250 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1251 ctx->pollfd_modify++;
1252 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1254 /* write some data on control pipe to interrupt event handlers */
1255 r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
1257 usbi_warn(ctx, "internal signalling write failed, closing anyway");
1258 do_close(ctx, dev_handle);
1259 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1260 ctx->pollfd_modify--;
1261 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1265 /* take event handling lock */
1266 libusb_lock_events(ctx);
1268 /* read the dummy data */
1269 r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
1271 usbi_warn(ctx, "internal signalling read failed, closing anyway");
1273 /* Close the device */
1274 do_close(ctx, dev_handle);
1276 /* we're done with modifying poll fds */
1277 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1278 ctx->pollfd_modify--;
1279 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1281 /* Release event handling lock and wake up event waiters */
1282 libusb_unlock_events(ctx);
1286 * Get the underlying device for a handle. This function does not modify
1287 * the reference count of the returned device, so do not feel compelled to
1288 * unreference it when you are done.
1289 * \param dev_handle a device handle
1290 * \returns the underlying device
1293 libusb_device * LIBUSB_CALL libusb_get_device(libusb_device_handle *dev_handle)
1295 return dev_handle->dev;
1299 * Determine the bConfigurationValue of the currently active configuration.
1301 * You could formulate your own control request to obtain this information,
1302 * but this function has the advantage that it may be able to retrieve the
1303 * information from operating system caches (no I/O involved).
1305 * If the OS does not cache this information, then this function will block
1306 * while a control transfer is submitted to retrieve the information.
1308 * This function will return a value of 0 in the <tt>config</tt> output
1309 * parameter if the device is in unconfigured state.
1311 * \param dev a device handle
1312 * \param config output location for the bConfigurationValue of the active
1313 * configuration (only valid for return code 0)
1314 * \returns 0 on success
1315 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1316 * \returns another LIBUSB_ERROR code on other failure
1318 int API_EXPORTED libusb_get_configuration(libusb_device_handle *dev,
1321 int r = LIBUSB_ERROR_NOT_SUPPORTED;
1324 if (usbi_backend->get_configuration)
1325 r = usbi_backend->get_configuration(dev, config);
1327 if (r == LIBUSB_ERROR_NOT_SUPPORTED) {
1329 usbi_dbg("falling back to control message");
1330 r = libusb_control_transfer(dev, LIBUSB_ENDPOINT_IN,
1331 LIBUSB_REQUEST_GET_CONFIGURATION, 0, 0, &tmp, 1, 1000);
1333 usbi_err(HANDLE_CTX(dev), "zero bytes returned in ctrl transfer?");
1334 r = LIBUSB_ERROR_IO;
1335 } else if (r == 1) {
1339 usbi_dbg("control failed, error %d", r);
1344 usbi_dbg("active config %d", *config);
1350 * Set the active configuration for a device.
1352 * The operating system may or may not have already set an active
1353 * configuration on the device. It is up to your application to ensure the
1354 * correct configuration is selected before you attempt to claim interfaces
1355 * and perform other operations.
1357 * If you call this function on a device already configured with the selected
1358 * configuration, then this function will act as a lightweight device reset:
1359 * it will issue a SET_CONFIGURATION request using the current configuration,
1360 * causing most USB-related device state to be reset (altsetting reset to zero,
1361 * endpoint halts cleared, toggles reset).
1363 * You cannot change/reset configuration if your application has claimed
1364 * interfaces - you should free them with libusb_release_interface() first.
1365 * You cannot change/reset configuration if other applications or drivers have
1366 * claimed interfaces.
1368 * A configuration value of -1 will put the device in unconfigured state.
1369 * The USB specifications state that a configuration value of 0 does this,
1370 * however buggy devices exist which actually have a configuration 0.
1372 * You should always use this function rather than formulating your own
1373 * SET_CONFIGURATION control request. This is because the underlying operating
1374 * system needs to know when such changes happen.
1376 * This is a blocking function.
1378 * \param dev a device handle
1379 * \param configuration the bConfigurationValue of the configuration you
1380 * wish to activate, or -1 if you wish to put the device in unconfigured state
1381 * \returns 0 on success
1382 * \returns LIBUSB_ERROR_NOT_FOUND if the requested configuration does not exist
1383 * \returns LIBUSB_ERROR_BUSY if interfaces are currently claimed
1384 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1385 * \returns another LIBUSB_ERROR code on other failure
1387 int API_EXPORTED libusb_set_configuration(libusb_device_handle *dev,
1390 usbi_dbg("configuration %d", configuration);
1391 return usbi_backend->set_configuration(dev, configuration);
1395 * Claim an interface on a given device handle. You must claim the interface
1396 * you wish to use before you can perform I/O on any of its endpoints.
1398 * It is legal to attempt to claim an already-claimed interface, in which
1399 * case libusbx just returns 0 without doing anything.
1401 * Claiming of interfaces is a purely logical operation; it does not cause
1402 * any requests to be sent over the bus. Interface claiming is used to
1403 * instruct the underlying operating system that your application wishes
1404 * to take ownership of the interface.
1406 * This is a non-blocking function.
1408 * \param dev a device handle
1409 * \param interface_number the <tt>bInterfaceNumber</tt> of the interface you
1411 * \returns 0 on success
1412 * \returns LIBUSB_ERROR_NOT_FOUND if the requested interface does not exist
1413 * \returns LIBUSB_ERROR_BUSY if another program or driver has claimed the
1415 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1416 * \returns a LIBUSB_ERROR code on other failure
1418 int API_EXPORTED libusb_claim_interface(libusb_device_handle *dev,
1419 int interface_number)
1423 usbi_dbg("interface %d", interface_number);
1424 if (interface_number >= USB_MAXINTERFACES)
1425 return LIBUSB_ERROR_INVALID_PARAM;
1427 if (!dev->dev->attached)
1428 return LIBUSB_ERROR_NO_DEVICE;
1430 usbi_mutex_lock(&dev->lock);
1431 if (dev->claimed_interfaces & (1 << interface_number))
1434 r = usbi_backend->claim_interface(dev, interface_number);
1436 dev->claimed_interfaces |= 1 << interface_number;
1439 usbi_mutex_unlock(&dev->lock);
1444 * Release an interface previously claimed with libusb_claim_interface(). You
1445 * should release all claimed interfaces before closing a device handle.
1447 * This is a blocking function. A SET_INTERFACE control request will be sent
1448 * to the device, resetting interface state to the first alternate setting.
1450 * \param dev a device handle
1451 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1452 * previously-claimed interface
1453 * \returns 0 on success
1454 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed
1455 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1456 * \returns another LIBUSB_ERROR code on other failure
1458 int API_EXPORTED libusb_release_interface(libusb_device_handle *dev,
1459 int interface_number)
1463 usbi_dbg("interface %d", interface_number);
1464 if (interface_number >= USB_MAXINTERFACES)
1465 return LIBUSB_ERROR_INVALID_PARAM;
1467 usbi_mutex_lock(&dev->lock);
1468 if (!(dev->claimed_interfaces & (1 << interface_number))) {
1469 r = LIBUSB_ERROR_NOT_FOUND;
1473 r = usbi_backend->release_interface(dev, interface_number);
1475 dev->claimed_interfaces &= ~(1 << interface_number);
1478 usbi_mutex_unlock(&dev->lock);
1483 * Activate an alternate setting for an interface. The interface must have
1484 * been previously claimed with libusb_claim_interface().
1486 * You should always use this function rather than formulating your own
1487 * SET_INTERFACE control request. This is because the underlying operating
1488 * system needs to know when such changes happen.
1490 * This is a blocking function.
1492 * \param dev a device handle
1493 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1494 * previously-claimed interface
1495 * \param alternate_setting the <tt>bAlternateSetting</tt> of the alternate
1496 * setting to activate
1497 * \returns 0 on success
1498 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed, or the
1499 * requested alternate setting does not exist
1500 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1501 * \returns another LIBUSB_ERROR code on other failure
1503 int API_EXPORTED libusb_set_interface_alt_setting(libusb_device_handle *dev,
1504 int interface_number, int alternate_setting)
1506 usbi_dbg("interface %d altsetting %d",
1507 interface_number, alternate_setting);
1508 if (interface_number >= USB_MAXINTERFACES)
1509 return LIBUSB_ERROR_INVALID_PARAM;
1511 usbi_mutex_lock(&dev->lock);
1512 if (!dev->dev->attached) {
1513 usbi_mutex_unlock(&dev->lock);
1514 return LIBUSB_ERROR_NO_DEVICE;
1517 if (!(dev->claimed_interfaces & (1 << interface_number))) {
1518 usbi_mutex_unlock(&dev->lock);
1519 return LIBUSB_ERROR_NOT_FOUND;
1521 usbi_mutex_unlock(&dev->lock);
1523 return usbi_backend->set_interface_altsetting(dev, interface_number,
1528 * Clear the halt/stall condition for an endpoint. Endpoints with halt status
1529 * are unable to receive or transmit data until the halt condition is stalled.
1531 * You should cancel all pending transfers before attempting to clear the halt
1534 * This is a blocking function.
1536 * \param dev a device handle
1537 * \param endpoint the endpoint to clear halt status
1538 * \returns 0 on success
1539 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
1540 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1541 * \returns another LIBUSB_ERROR code on other failure
1543 int API_EXPORTED libusb_clear_halt(libusb_device_handle *dev,
1544 unsigned char endpoint)
1546 usbi_dbg("endpoint %x", endpoint);
1547 if (!dev->dev->attached)
1548 return LIBUSB_ERROR_NO_DEVICE;
1550 return usbi_backend->clear_halt(dev, endpoint);
1554 * Perform a USB port reset to reinitialize a device. The system will attempt
1555 * to restore the previous configuration and alternate settings after the
1556 * reset has completed.
1558 * If the reset fails, the descriptors change, or the previous state cannot be
1559 * restored, the device will appear to be disconnected and reconnected. This
1560 * means that the device handle is no longer valid (you should close it) and
1561 * rediscover the device. A return code of LIBUSB_ERROR_NOT_FOUND indicates
1562 * when this is the case.
1564 * This is a blocking function which usually incurs a noticeable delay.
1566 * \param dev a handle of the device to reset
1567 * \returns 0 on success
1568 * \returns LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the
1569 * device has been disconnected
1570 * \returns another LIBUSB_ERROR code on other failure
1572 int API_EXPORTED libusb_reset_device(libusb_device_handle *dev)
1575 if (!dev->dev->attached)
1576 return LIBUSB_ERROR_NO_DEVICE;
1578 return usbi_backend->reset_device(dev);
1582 * Determine if a kernel driver is active on an interface. If a kernel driver
1583 * is active, you cannot claim the interface, and libusbx will be unable to
1586 * This functionality is not available on Windows.
1588 * \param dev a device handle
1589 * \param interface_number the interface to check
1590 * \returns 0 if no kernel driver is active
1591 * \returns 1 if a kernel driver is active
1592 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1593 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1595 * \returns another LIBUSB_ERROR code on other failure
1596 * \see libusb_detach_kernel_driver()
1598 int API_EXPORTED libusb_kernel_driver_active(libusb_device_handle *dev,
1599 int interface_number)
1601 usbi_dbg("interface %d", interface_number);
1603 if (!dev->dev->attached)
1604 return LIBUSB_ERROR_NO_DEVICE;
1606 if (usbi_backend->kernel_driver_active)
1607 return usbi_backend->kernel_driver_active(dev, interface_number);
1609 return LIBUSB_ERROR_NOT_SUPPORTED;
1613 * Detach a kernel driver from an interface. If successful, you will then be
1614 * able to claim the interface and perform I/O.
1616 * This functionality is not available on Darwin or Windows.
1618 * Note that libusbx itself also talks to the device through a special kernel
1619 * driver, if this driver is already attached to the device, this call will
1620 * not detach it and return LIBUSB_ERROR_NOT_FOUND.
1622 * \param dev a device handle
1623 * \param interface_number the interface to detach the driver from
1624 * \returns 0 on success
1625 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1626 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1627 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1628 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1630 * \returns another LIBUSB_ERROR code on other failure
1631 * \see libusb_kernel_driver_active()
1633 int API_EXPORTED libusb_detach_kernel_driver(libusb_device_handle *dev,
1634 int interface_number)
1636 usbi_dbg("interface %d", interface_number);
1638 if (!dev->dev->attached)
1639 return LIBUSB_ERROR_NO_DEVICE;
1641 if (usbi_backend->detach_kernel_driver)
1642 return usbi_backend->detach_kernel_driver(dev, interface_number);
1644 return LIBUSB_ERROR_NOT_SUPPORTED;
1648 * Re-attach an interface's kernel driver, which was previously detached
1649 * using libusb_detach_kernel_driver(). This call is only effective on
1650 * Linux and returns LIBUSB_ERROR_NOT_SUPPORTED on all other platforms.
1652 * This functionality is not available on Darwin or Windows.
1654 * \param dev a device handle
1655 * \param interface_number the interface to attach the driver from
1656 * \returns 0 on success
1657 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1658 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1659 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1660 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1662 * \returns LIBUSB_ERROR_BUSY if the driver cannot be attached because the
1663 * interface is claimed by a program or driver
1664 * \returns another LIBUSB_ERROR code on other failure
1665 * \see libusb_kernel_driver_active()
1667 int API_EXPORTED libusb_attach_kernel_driver(libusb_device_handle *dev,
1668 int interface_number)
1670 usbi_dbg("interface %d", interface_number);
1672 if (!dev->dev->attached)
1673 return LIBUSB_ERROR_NO_DEVICE;
1675 if (usbi_backend->attach_kernel_driver)
1676 return usbi_backend->attach_kernel_driver(dev, interface_number);
1678 return LIBUSB_ERROR_NOT_SUPPORTED;
1682 * Set log message verbosity.
1684 * The default level is LIBUSB_LOG_LEVEL_NONE, which means no messages are ever
1685 * printed. If you choose to increase the message verbosity level, ensure
1686 * that your application does not close the stdout/stderr file descriptors.
1688 * You are advised to use level LIBUSB_LOG_LEVEL_WARNING. libusbx is conservative
1689 * with its message logging and most of the time, will only log messages that
1690 * explain error conditions and other oddities. This will help you debug
1693 * If the LIBUSB_DEBUG environment variable was set when libusbx was
1694 * initialized, this function does nothing: the message verbosity is fixed
1695 * to the value in the environment variable.
1697 * If libusbx was compiled without any message logging, this function does
1698 * nothing: you'll never get any messages.
1700 * If libusbx was compiled with verbose debug message logging, this function
1701 * does nothing: you'll always get messages from all levels.
1703 * \param ctx the context to operate on, or NULL for the default context
1704 * \param level debug level to set
1706 void API_EXPORTED libusb_set_debug(libusb_context *ctx, int level)
1708 USBI_GET_CONTEXT(ctx);
1709 if (!ctx->debug_fixed)
1714 * Initialize libusb. This function must be called before calling any other
1717 * If you do not provide an output location for a context pointer, a default
1718 * context will be created. If there was already a default context, it will
1719 * be reused (and nothing will be initialized/reinitialized).
1721 * \param context Optional output location for context pointer.
1722 * Only valid on return code 0.
1723 * \returns 0 on success, or a LIBUSB_ERROR code on failure
1726 int API_EXPORTED libusb_init(libusb_context **context)
1728 struct libusb_device *dev, *next;
1729 char *dbg = getenv("LIBUSB_DEBUG");
1730 struct libusb_context *ctx;
1731 static int first_init = 1;
1734 usbi_mutex_static_lock(&default_context_lock);
1736 if (!timestamp_origin.tv_sec) {
1737 usbi_gettimeofday(×tamp_origin, NULL);
1740 if (!context && usbi_default_context) {
1741 usbi_dbg("reusing default context");
1742 default_context_refcnt++;
1743 usbi_mutex_static_unlock(&default_context_lock);
1747 ctx = calloc(1, sizeof(*ctx));
1749 r = LIBUSB_ERROR_NO_MEM;
1753 #ifdef ENABLE_DEBUG_LOGGING
1754 ctx->debug = LIBUSB_LOG_LEVEL_DEBUG;
1758 ctx->debug = atoi(dbg);
1760 ctx->debug_fixed = 1;
1763 /* default context should be initialized before calling usbi_dbg */
1764 if (!usbi_default_context) {
1765 usbi_default_context = ctx;
1766 default_context_refcnt++;
1767 usbi_dbg("created default context");
1770 usbi_dbg("libusbx v%d.%d.%d.%d", libusb_version_internal.major, libusb_version_internal.minor,
1771 libusb_version_internal.micro, libusb_version_internal.nano);
1773 usbi_mutex_init(&ctx->usb_devs_lock, NULL);
1774 usbi_mutex_init(&ctx->open_devs_lock, NULL);
1775 usbi_mutex_init(&ctx->hotplug_cbs_lock, NULL);
1776 list_init(&ctx->usb_devs);
1777 list_init(&ctx->open_devs);
1778 list_init(&ctx->hotplug_cbs);
1780 usbi_mutex_static_lock(&active_contexts_lock);
1783 list_init (&active_contexts_list);
1785 list_add (&ctx->list, &active_contexts_list);
1786 usbi_mutex_static_unlock(&active_contexts_lock);
1788 if (usbi_backend->init) {
1789 r = usbi_backend->init(ctx);
1794 r = usbi_io_init(ctx);
1796 goto err_backend_exit;
1798 usbi_mutex_static_unlock(&default_context_lock);
1806 if (usbi_backend->exit)
1807 usbi_backend->exit();
1809 if (ctx == usbi_default_context)
1810 usbi_default_context = NULL;
1812 usbi_mutex_destroy(&ctx->open_devs_lock);
1813 usbi_mutex_destroy(&ctx->usb_devs_lock);
1814 usbi_mutex_destroy(&ctx->hotplug_cbs_lock);
1816 usbi_mutex_static_lock(&active_contexts_lock);
1817 list_del (&ctx->list);
1818 usbi_mutex_static_unlock(&active_contexts_lock);
1820 usbi_mutex_lock(&ctx->usb_devs_lock);
1821 list_for_each_entry_safe(dev, next, &ctx->usb_devs, list, struct libusb_device) {
1822 list_del(&dev->list);
1823 libusb_unref_device(dev);
1825 usbi_mutex_unlock(&ctx->usb_devs_lock);
1829 usbi_mutex_static_unlock(&default_context_lock);
1834 * Deinitialize libusb. Should be called after closing all open devices and
1835 * before your application terminates.
1836 * \param ctx the context to deinitialize, or NULL for the default context
1838 void API_EXPORTED libusb_exit(struct libusb_context *ctx)
1840 struct libusb_device *dev, *next;
1843 USBI_GET_CONTEXT(ctx);
1845 /* if working with default context, only actually do the deinitialization
1846 * if we're the last user */
1847 usbi_mutex_static_lock(&default_context_lock);
1848 if (ctx == usbi_default_context) {
1849 if (--default_context_refcnt > 0) {
1850 usbi_dbg("not destroying default context");
1851 usbi_mutex_static_unlock(&default_context_lock);
1854 usbi_dbg("destroying default context");
1855 usbi_default_context = NULL;
1857 usbi_mutex_static_unlock(&default_context_lock);
1859 usbi_mutex_static_lock(&active_contexts_lock);
1860 list_del (&ctx->list);
1861 usbi_mutex_static_unlock(&active_contexts_lock);
1863 usbi_hotplug_deregister_all(ctx);
1865 usbi_mutex_lock(&ctx->usb_devs_lock);
1866 list_for_each_entry_safe(dev, next, &ctx->usb_devs, list, struct libusb_device) {
1867 list_del(&dev->list);
1868 libusb_unref_device(dev);
1870 usbi_mutex_unlock(&ctx->usb_devs_lock);
1872 /* a little sanity check. doesn't bother with open_devs locking because
1873 * unless there is an application bug, nobody will be accessing this. */
1874 if (!list_empty(&ctx->open_devs))
1875 usbi_warn(ctx, "application left some devices open");
1878 if (usbi_backend->exit)
1879 usbi_backend->exit();
1881 usbi_mutex_destroy(&ctx->open_devs_lock);
1882 usbi_mutex_destroy(&ctx->usb_devs_lock);
1883 usbi_mutex_destroy(&ctx->hotplug_cbs_lock);
1888 * Check at runtime if the loaded library has a given capability.
1889 * This call should be performed after \ref libusb_init(), to ensure the
1890 * backend has updated its capability set.
1892 * \param capability the \ref libusb_capability to check for
1893 * \returns nonzero if the running library has the capability, 0 otherwise
1895 int API_EXPORTED libusb_has_capability(uint32_t capability)
1897 switch (capability) {
1898 case LIBUSB_CAP_HAS_CAPABILITY:
1900 case LIBUSB_CAP_HAS_HOTPLUG:
1901 return !(usbi_backend->get_device_list);
1902 case LIBUSB_CAP_HAS_HID_ACCESS:
1903 return (usbi_backend->caps & USBI_CAP_HAS_HID_ACCESS);
1904 case LIBUSB_CAP_SUPPORTS_DETACH_KERNEL_DRIVER:
1905 return (usbi_backend->caps & USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER);
1910 /* this is defined in libusbi.h if needed */
1911 #ifdef LIBUSB_GETTIMEOFDAY_WIN32
1914 * Implementation according to:
1915 * The Open Group Base Specifications Issue 6
1916 * IEEE Std 1003.1, 2004 Edition
1920 * THIS SOFTWARE IS NOT COPYRIGHTED
1922 * This source code is offered for use in the public domain. You may
1923 * use, modify or distribute it freely.
1925 * This code is distributed in the hope that it will be useful but
1926 * WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
1927 * DISCLAIMED. This includes but is not limited to warranties of
1928 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
1931 * Danny Smith <dannysmith@users.sourceforge.net>
1934 /* Offset between 1/1/1601 and 1/1/1970 in 100 nanosec units */
1935 #define _W32_FT_OFFSET (116444736000000000)
1937 int usbi_gettimeofday(struct timeval *tp, void *tzp)
1940 unsigned __int64 ns100; /* Time since 1 Jan 1601, in 100ns units */
1946 #if defined(OS_WINCE)
1949 SystemTimeToFileTime(&st, &_now.ft);
1951 GetSystemTimeAsFileTime (&_now.ft);
1953 tp->tv_usec=(long)((_now.ns100 / 10) % 1000000 );
1954 tp->tv_sec= (long)((_now.ns100 - _W32_FT_OFFSET) / 10000000);
1956 /* Always return 0 as per Open Group Base Specifications Issue 6.
1957 Do not set errno on error. */
1962 void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
1963 const char *function, const char *format, va_list args)
1965 const char *prefix = "";
1968 static int has_debug_header_been_displayed = 0;
1970 #ifdef ENABLE_DEBUG_LOGGING
1974 USBI_GET_CONTEXT(ctx);
1977 global_debug = (ctx->debug == LIBUSB_LOG_LEVEL_DEBUG);
1980 if (level == LIBUSB_LOG_LEVEL_WARNING && ctx->debug < LIBUSB_LOG_LEVEL_WARNING)
1982 if (level == LIBUSB_LOG_LEVEL_INFO && ctx->debug < LIBUSB_LOG_LEVEL_INFO)
1984 if (level == LIBUSB_LOG_LEVEL_DEBUG && ctx->debug < LIBUSB_LOG_LEVEL_DEBUG)
1988 usbi_gettimeofday(&now, NULL);
1989 if ((global_debug) && (!has_debug_header_been_displayed)) {
1990 has_debug_header_been_displayed = 1;
1991 fprintf(stderr, "[timestamp] [threadID] facility level [function call] <message>\n");
1992 fprintf(stderr, "--------------------------------------------------------------------------------\n");
1994 if (now.tv_usec < timestamp_origin.tv_usec) {
1996 now.tv_usec += 1000000;
1998 now.tv_sec -= timestamp_origin.tv_sec;
1999 now.tv_usec -= timestamp_origin.tv_usec;
2002 case LIBUSB_LOG_LEVEL_INFO:
2005 case LIBUSB_LOG_LEVEL_WARNING:
2008 case LIBUSB_LOG_LEVEL_ERROR:
2011 case LIBUSB_LOG_LEVEL_DEBUG:
2014 case LIBUSB_LOG_LEVEL_NONE:
2022 fprintf(stderr, "[%2d.%06d] [%08x] libusbx: %s [%s] ",
2023 (int)now.tv_sec, (int)now.tv_usec, usbi_get_tid(), prefix, function);
2025 fprintf(stderr, "libusbx: %s [%s] ", prefix, function);
2028 vfprintf(stderr, format, args);
2030 fprintf(stderr, "\n");
2033 void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
2034 const char *function, const char *format, ...)
2038 va_start (args, format);
2039 usbi_log_v(ctx, level, function, format, args);
2044 * Returns a constant NULL-terminated string with the ASCII name of a libusbx
2045 * error or transfer status code. The caller must not free() the returned
2048 * \param error_code The \ref libusb_error or libusb_transfer_status code to
2049 * return the name of.
2050 * \returns The error name, or the string **UNKNOWN** if the value of
2051 * error_code is not a known error / status code.
2053 DEFAULT_VISIBILITY const char * LIBUSB_CALL libusb_error_name(int error_code)
2055 switch (error_code) {
2056 case LIBUSB_ERROR_IO:
2057 return "LIBUSB_ERROR_IO";
2058 case LIBUSB_ERROR_INVALID_PARAM:
2059 return "LIBUSB_ERROR_INVALID_PARAM";
2060 case LIBUSB_ERROR_ACCESS:
2061 return "LIBUSB_ERROR_ACCESS";
2062 case LIBUSB_ERROR_NO_DEVICE:
2063 return "LIBUSB_ERROR_NO_DEVICE";
2064 case LIBUSB_ERROR_NOT_FOUND:
2065 return "LIBUSB_ERROR_NOT_FOUND";
2066 case LIBUSB_ERROR_BUSY:
2067 return "LIBUSB_ERROR_BUSY";
2068 case LIBUSB_ERROR_TIMEOUT:
2069 return "LIBUSB_ERROR_TIMEOUT";
2070 case LIBUSB_ERROR_OVERFLOW:
2071 return "LIBUSB_ERROR_OVERFLOW";
2072 case LIBUSB_ERROR_PIPE:
2073 return "LIBUSB_ERROR_PIPE";
2074 case LIBUSB_ERROR_INTERRUPTED:
2075 return "LIBUSB_ERROR_INTERRUPTED";
2076 case LIBUSB_ERROR_NO_MEM:
2077 return "LIBUSB_ERROR_NO_MEM";
2078 case LIBUSB_ERROR_NOT_SUPPORTED:
2079 return "LIBUSB_ERROR_NOT_SUPPORTED";
2080 case LIBUSB_ERROR_OTHER:
2081 return "LIBUSB_ERROR_OTHER";
2083 case LIBUSB_TRANSFER_ERROR:
2084 return "LIBUSB_TRANSFER_ERROR";
2085 case LIBUSB_TRANSFER_TIMED_OUT:
2086 return "LIBUSB_TRANSFER_TIMED_OUT";
2087 case LIBUSB_TRANSFER_CANCELLED:
2088 return "LIBUSB_TRANSFER_CANCELLED";
2089 case LIBUSB_TRANSFER_STALL:
2090 return "LIBUSB_TRANSFER_STALL";
2091 case LIBUSB_TRANSFER_NO_DEVICE:
2092 return "LIBUSB_TRANSFER_NO_DEVICE";
2093 case LIBUSB_TRANSFER_OVERFLOW:
2094 return "LIBUSB_TRANSFER_OVERFLOW";
2097 return "LIBUSB_SUCCESS / LIBUSB_TRANSFER_COMPLETED";
2099 return "**UNKNOWN**";
2104 * Returns a pointer to const struct libusb_version with the version
2105 * (major, minor, micro, nano and rc) of the running library.
2108 const struct libusb_version * LIBUSB_CALL libusb_get_version(void)
2110 return &libusb_version_internal;