1 /* -*- Mode: C; indent-tabs-mode:t ; c-basic-offset:8 -*- */
3 * Core functions for libusb
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 #include <android/log.h>
48 const struct usbi_os_backend * const usbi_backend = &linux_usbfs_backend;
49 #elif defined(OS_DARWIN)
50 const struct usbi_os_backend * const usbi_backend = &darwin_backend;
51 #elif defined(OS_OPENBSD)
52 const struct usbi_os_backend * const usbi_backend = &openbsd_backend;
53 #elif defined(OS_NETBSD)
54 const struct usbi_os_backend * const usbi_backend = &netbsd_backend;
55 #elif defined(OS_WINDOWS)
56 const struct usbi_os_backend * const usbi_backend = &windows_backend;
57 #elif defined(OS_WINCE)
58 const struct usbi_os_backend * const usbi_backend = &wince_backend;
60 #error "Unsupported OS"
63 struct libusb_context *usbi_default_context = NULL;
64 static const struct libusb_version libusb_version_internal =
65 { LIBUSB_MAJOR, LIBUSB_MINOR, LIBUSB_MICRO, LIBUSB_NANO,
66 LIBUSB_RC, "http://libusb.info" };
67 static int default_context_refcnt = 0;
68 static usbi_mutex_static_t default_context_lock = USBI_MUTEX_INITIALIZER;
69 static struct timeval timestamp_origin = { 0, 0 };
71 usbi_mutex_static_t active_contexts_lock = USBI_MUTEX_INITIALIZER;
72 struct list_head active_contexts_list;
75 * \mainpage libusb-1.0 API Reference
77 * \section intro Introduction
79 * libusb is an open source library that allows you to communicate with USB
80 * devices from userspace. For more info, see the
81 * <a href="http://libusb.info">libusb homepage</a>.
83 * This documentation is aimed at application developers wishing to
84 * communicate with USB peripherals from their own software. After reviewing
85 * this documentation, feedback and questions can be sent to the
86 * <a href="http://mailing-list.libusb.info">libusb-devel mailing list</a>.
88 * This documentation assumes knowledge of how to operate USB devices from
89 * a software standpoint (descriptors, configurations, interfaces, endpoints,
90 * control/bulk/interrupt/isochronous transfers, etc). Full information
91 * can be found in the <a href="http://www.usb.org/developers/docs/">USB 3.0
92 * Specification</a> which is available for free download. You can probably
93 * find less verbose introductions by searching the web.
95 * \section features Library features
97 * - All transfer types supported (control/bulk/interrupt/isochronous)
98 * - 2 transfer interfaces:
99 * -# Synchronous (simple)
100 * -# Asynchronous (more complicated, but more powerful)
101 * - Thread safe (although the asynchronous interface means that you
102 * usually won't need to thread)
103 * - Lightweight with lean API
104 * - Compatible with libusb-0.1 through the libusb-compat-0.1 translation layer
105 * - Hotplug support (on some platforms). See \ref hotplug.
107 * \section gettingstarted Getting Started
109 * To begin reading the API documentation, start with the Modules page which
110 * links to the different categories of libusb's functionality.
112 * One decision you will have to make is whether to use the synchronous
113 * or the asynchronous data transfer interface. The \ref io documentation
114 * provides some insight into this topic.
116 * Some example programs can be found in the libusb source distribution under
117 * the "examples" subdirectory. The libusb homepage includes a list of
118 * real-life project examples which use libusb.
120 * \section errorhandling Error handling
122 * libusb functions typically return 0 on success or a negative error code
123 * on failure. These negative error codes relate to LIBUSB_ERROR constants
124 * which are listed on the \ref misc "miscellaneous" documentation page.
126 * \section msglog Debug message logging
128 * libusb uses stderr for all logging. By default, logging is set to NONE,
129 * which means that no output will be produced. However, unless the library
130 * has been compiled with logging disabled, then any application calls to
131 * libusb_set_debug(), or the setting of the environmental variable
132 * LIBUSB_DEBUG outside of the application, can result in logging being
133 * produced. Your application should therefore not close stderr, but instead
134 * direct it to the null device if its output is undesireable.
136 * The libusb_set_debug() function can be used to enable logging of certain
137 * messages. Under standard configuration, libusb doesn't really log much
138 * so you are advised to use this function to enable all error/warning/
139 * informational messages. It will help debug problems with your software.
141 * The logged messages are unstructured. There is no one-to-one correspondence
142 * between messages being logged and success or failure return codes from
143 * libusb functions. There is no format to the messages, so you should not
144 * try to capture or parse them. They are not and will not be localized.
145 * These messages are not intended to being passed to your application user;
146 * instead, you should interpret the error codes returned from libusb functions
147 * and provide appropriate notification to the user. The messages are simply
148 * there to aid you as a programmer, and if you're confused because you're
149 * getting a strange error code from a libusb function, enabling message
150 * logging may give you a suitable explanation.
152 * The LIBUSB_DEBUG environment variable can be used to enable message logging
153 * at run-time. This environment variable should be set to a log level number,
154 * which is interpreted the same as the libusb_set_debug() parameter. When this
155 * environment variable is set, the message logging verbosity level is fixed
156 * and libusb_set_debug() effectively does nothing.
158 * libusb can be compiled without any logging functions, useful for embedded
159 * systems. In this case, libusb_set_debug() and the LIBUSB_DEBUG environment
160 * variable have no effects.
162 * libusb can also be compiled with verbose debugging messages always. When
163 * the library is compiled in this way, all messages of all verbosities are
164 * always logged. libusb_set_debug() and the LIBUSB_DEBUG environment variable
167 * \section remarks Other remarks
169 * libusb does have imperfections. The \ref caveats "caveats" page attempts
174 * \page caveats Caveats
176 * \section devresets Device resets
178 * The libusb_reset_device() function allows you to reset a device. If your
179 * program has to call such a function, it should obviously be aware that
180 * the reset will cause device state to change (e.g. register values may be
183 * The problem is that any other program could reset the device your program
184 * is working with, at any time. libusb does not offer a mechanism to inform
185 * you when this has happened, so if someone else resets your device it will
186 * not be clear to your own program why the device state has changed.
188 * Ultimately, this is a limitation of writing drivers in userspace.
189 * Separation from the USB stack in the underlying kernel makes it difficult
190 * for the operating system to deliver such notifications to your program.
191 * The Linux kernel USB stack allows such reset notifications to be delivered
192 * to in-kernel USB drivers, but it is not clear how such notifications could
193 * be delivered to second-class drivers that live in userspace.
195 * \section blockonly Blocking-only functionality
197 * The functionality listed below is only available through synchronous,
198 * blocking functions. There are no asynchronous/non-blocking alternatives,
199 * and no clear ways of implementing these.
201 * - Configuration activation (libusb_set_configuration())
202 * - Interface/alternate setting activation (libusb_set_interface_alt_setting())
203 * - Releasing of interfaces (libusb_release_interface())
204 * - Clearing of halt/stall condition (libusb_clear_halt())
205 * - Device resets (libusb_reset_device())
207 * \section configsel Configuration selection and handling
209 * When libusb presents a device handle to an application, there is a chance
210 * that the corresponding device may be in unconfigured state. For devices
211 * with multiple configurations, there is also a chance that the configuration
212 * currently selected is not the one that the application wants to use.
214 * The obvious solution is to add a call to libusb_set_configuration() early
215 * on during your device initialization routines, but there are caveats to
217 * -# If the device is already in the desired configuration, calling
218 * libusb_set_configuration() using the same configuration value will cause
219 * a lightweight device reset. This may not be desirable behaviour.
220 * -# libusb will be unable to change configuration if the device is in
221 * another configuration and other programs or drivers have claimed
222 * interfaces under that configuration.
223 * -# In the case where the desired configuration is already active, libusb
224 * may not even be able to perform a lightweight device reset. For example,
225 * take my USB keyboard with fingerprint reader: I'm interested in driving
226 * the fingerprint reader interface through libusb, but the kernel's
227 * USB-HID driver will almost always have claimed the keyboard interface.
228 * Because the kernel has claimed an interface, it is not even possible to
229 * perform the lightweight device reset, so libusb_set_configuration() will
230 * fail. (Luckily the device in question only has a single configuration.)
232 * One solution to some of the above problems is to consider the currently
233 * active configuration. If the configuration we want is already active, then
234 * we don't have to select any configuration:
236 cfg = libusb_get_configuration(dev);
238 libusb_set_configuration(dev, desired);
241 * This is probably suitable for most scenarios, but is inherently racy:
242 * another application or driver may change the selected configuration
243 * <em>after</em> the libusb_get_configuration() call.
245 * Even in cases where libusb_set_configuration() succeeds, consider that other
246 * applications or drivers may change configuration after your application
247 * calls libusb_set_configuration().
249 * One possible way to lock your device into a specific configuration is as
251 * -# Set the desired configuration (or use the logic above to realise that
252 * it is already in the desired configuration)
253 * -# Claim the interface that you wish to use
254 * -# Check that the currently active configuration is the one that you want
257 * The above method works because once an interface is claimed, no application
258 * or driver is able to select another configuration.
260 * \section earlycomp Early transfer completion
262 * NOTE: This section is currently Linux-centric. I am not sure if any of these
263 * considerations apply to Darwin or other platforms.
265 * When a transfer completes early (i.e. when less data is received/sent in
266 * any one packet than the transfer buffer allows for) then libusb is designed
267 * to terminate the transfer immediately, not transferring or receiving any
268 * more data unless other transfers have been queued by the user.
270 * On legacy platforms, libusb is unable to do this in all situations. After
271 * the incomplete packet occurs, "surplus" data may be transferred. For recent
272 * versions of libusb, this information is kept (the data length of the
273 * transfer is updated) and, for device-to-host transfers, any surplus data was
274 * added to the buffer. Still, this is not a nice solution because it loses the
275 * information about the end of the short packet, and the user probably wanted
276 * that surplus data to arrive in the next logical transfer.
279 * \section zlp Zero length packets
281 * - libusb is able to send a packet of zero length to an endpoint simply by
282 * submitting a transfer of zero length.
283 * - The \ref libusb_transfer_flags::LIBUSB_TRANSFER_ADD_ZERO_PACKET
284 * "LIBUSB_TRANSFER_ADD_ZERO_PACKET" flag is currently only supported on Linux.
288 * \page contexts Contexts
290 * It is possible that libusb may be used simultaneously from two independent
291 * libraries linked into the same executable. For example, if your application
292 * has a plugin-like system which allows the user to dynamically load a range
293 * of modules into your program, it is feasible that two independently
294 * developed modules may both use libusb.
296 * libusb is written to allow for these multiple user scenarios. The two
297 * "instances" of libusb will not interfere: libusb_set_debug() calls
298 * from one user will not affect the same settings for other users, other
299 * users can continue using libusb after one of them calls libusb_exit(), etc.
301 * This is made possible through libusb's <em>context</em> concept. When you
302 * call libusb_init(), you are (optionally) given a context. You can then pass
303 * this context pointer back into future libusb functions.
305 * In order to keep things simple for more simplistic applications, it is
306 * legal to pass NULL to all functions requiring a context pointer (as long as
307 * you're sure no other code will attempt to use libusb from the same process).
308 * When you pass NULL, the default context will be used. The default context
309 * is created the first time a process calls libusb_init() when no other
310 * context is alive. Contexts are destroyed during libusb_exit().
312 * The default context is reference-counted and can be shared. That means that
313 * if libusb_init(NULL) is called twice within the same process, the two
314 * users end up sharing the same context. The deinitialization and freeing of
315 * the default context will only happen when the last user calls libusb_exit().
316 * In other words, the default context is created and initialized when its
317 * reference count goes from 0 to 1, and is deinitialized and destroyed when
318 * its reference count goes from 1 to 0.
320 * You may be wondering why only a subset of libusb functions require a
321 * context pointer in their function definition. Internally, libusb stores
322 * context pointers in other objects (e.g. libusb_device instances) and hence
323 * can infer the context from those objects.
327 * @defgroup lib Library initialization/deinitialization
328 * This page details how to initialize and deinitialize libusb. Initialization
329 * must be performed before using any libusb functionality, and similarly you
330 * must not call any libusb functions after deinitialization.
334 * @defgroup dev Device handling and enumeration
335 * The functionality documented below is designed to help with the following
337 * - Enumerating the USB devices currently attached to the system
338 * - Choosing a device to operate from your software
339 * - Opening and closing the chosen device
341 * \section nutshell In a nutshell...
343 * The description below really makes things sound more complicated than they
344 * actually are. The following sequence of function calls will be suitable
345 * for almost all scenarios and does not require you to have such a deep
346 * understanding of the resource management issues:
349 libusb_device **list;
350 libusb_device *found = NULL;
351 ssize_t cnt = libusb_get_device_list(NULL, &list);
357 for (i = 0; i < cnt; i++) {
358 libusb_device *device = list[i];
359 if (is_interesting(device)) {
366 libusb_device_handle *handle;
368 err = libusb_open(found, &handle);
374 libusb_free_device_list(list, 1);
377 * The two important points:
378 * - You asked libusb_free_device_list() to unreference the devices (2nd
380 * - You opened the device before freeing the list and unreferencing the
383 * If you ended up with a handle, you can now proceed to perform I/O on the
386 * \section devshandles Devices and device handles
387 * libusb has a concept of a USB device, represented by the
388 * \ref libusb_device opaque type. A device represents a USB device that
389 * is currently or was previously connected to the system. Using a reference
390 * to a device, you can determine certain information about the device (e.g.
391 * you can read the descriptor data).
393 * The libusb_get_device_list() function can be used to obtain a list of
394 * devices currently connected to the system. This is known as device
397 * Just because you have a reference to a device does not mean it is
398 * necessarily usable. The device may have been unplugged, you may not have
399 * permission to operate such device, or another program or driver may be
402 * When you've found a device that you'd like to operate, you must ask
403 * libusb to open the device using the libusb_open() function. Assuming
404 * success, libusb then returns you a <em>device handle</em>
405 * (a \ref libusb_device_handle pointer). All "real" I/O operations then
406 * operate on the handle rather than the original device pointer.
408 * \section devref Device discovery and reference counting
410 * Device discovery (i.e. calling libusb_get_device_list()) returns a
411 * freshly-allocated list of devices. The list itself must be freed when
412 * you are done with it. libusb also needs to know when it is OK to free
413 * the contents of the list - the devices themselves.
415 * To handle these issues, libusb provides you with two separate items:
416 * - A function to free the list itself
417 * - A reference counting system for the devices inside
419 * New devices presented by the libusb_get_device_list() function all have a
420 * reference count of 1. You can increase and decrease reference count using
421 * libusb_ref_device() and libusb_unref_device(). A device is destroyed when
422 * its reference count reaches 0.
424 * With the above information in mind, the process of opening a device can
425 * be viewed as follows:
426 * -# Discover devices using libusb_get_device_list().
427 * -# Choose the device that you want to operate, and call libusb_open().
428 * -# Unref all devices in the discovered device list.
429 * -# Free the discovered device list.
431 * The order is important - you must not unreference the device before
432 * attempting to open it, because unreferencing it may destroy the device.
434 * For convenience, the libusb_free_device_list() function includes a
435 * parameter to optionally unreference all the devices in the list before
436 * freeing the list itself. This combines steps 3 and 4 above.
438 * As an implementation detail, libusb_open() actually adds a reference to
439 * the device in question. This is because the device remains available
440 * through the handle via libusb_get_device(). The reference is deleted during
444 /** @defgroup misc Miscellaneous */
446 /* we traverse usbfs without knowing how many devices we are going to find.
447 * so we create this discovered_devs model which is similar to a linked-list
448 * which grows when required. it can be freed once discovery has completed,
449 * eliminating the need for a list node in the libusb_device structure
451 #define DISCOVERED_DEVICES_SIZE_STEP 8
453 static struct discovered_devs *discovered_devs_alloc(void)
455 struct discovered_devs *ret =
456 malloc(sizeof(*ret) + (sizeof(void *) * DISCOVERED_DEVICES_SIZE_STEP));
460 ret->capacity = DISCOVERED_DEVICES_SIZE_STEP;
465 /* append a device to the discovered devices collection. may realloc itself,
466 * returning new discdevs. returns NULL on realloc failure. */
467 struct discovered_devs *discovered_devs_append(
468 struct discovered_devs *discdevs, struct libusb_device *dev)
470 size_t len = discdevs->len;
473 /* if there is space, just append the device */
474 if (len < discdevs->capacity) {
475 discdevs->devices[len] = libusb_ref_device(dev);
480 /* exceeded capacity, need to grow */
481 usbi_dbg("need to increase capacity");
482 capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
483 discdevs = usbi_reallocf(discdevs,
484 sizeof(*discdevs) + (sizeof(void *) * capacity));
486 discdevs->capacity = capacity;
487 discdevs->devices[len] = libusb_ref_device(dev);
494 static void discovered_devs_free(struct discovered_devs *discdevs)
498 for (i = 0; i < discdevs->len; i++)
499 libusb_unref_device(discdevs->devices[i]);
504 /* Allocate a new device with a specific session ID. The returned device has
505 * a reference count of 1. */
506 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
507 unsigned long session_id)
509 size_t priv_size = usbi_backend->device_priv_size;
510 struct libusb_device *dev = calloc(1, sizeof(*dev) + priv_size);
516 r = usbi_mutex_init(&dev->lock, NULL);
524 dev->session_data = session_id;
525 dev->speed = LIBUSB_SPEED_UNKNOWN;
527 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
528 usbi_connect_device (dev);
534 void usbi_connect_device(struct libusb_device *dev)
536 libusb_hotplug_message message;
539 memset(&message, 0, sizeof(message));
540 message.event = LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED;
541 message.device = dev;
544 usbi_mutex_lock(&dev->ctx->usb_devs_lock);
545 list_add(&dev->list, &dev->ctx->usb_devs);
546 usbi_mutex_unlock(&dev->ctx->usb_devs_lock);
548 /* Signal that an event has occurred for this device if we support hotplug AND
549 * the hotplug pipe is ready. This prevents an event from getting raised during
550 * initial enumeration. */
551 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG) && dev->ctx->hotplug_pipe[1] > 0) {
552 ret = usbi_write(dev->ctx->hotplug_pipe[1], &message, sizeof(message));
553 if (sizeof (message) != ret) {
554 usbi_err(DEVICE_CTX(dev), "error writing hotplug message");
559 void usbi_disconnect_device(struct libusb_device *dev)
561 libusb_hotplug_message message;
562 struct libusb_context *ctx = dev->ctx;
565 memset(&message, 0, sizeof(message));
566 message.event = LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT;
567 message.device = dev;
568 usbi_mutex_lock(&dev->lock);
570 usbi_mutex_unlock(&dev->lock);
572 usbi_mutex_lock(&ctx->usb_devs_lock);
573 list_del(&dev->list);
574 usbi_mutex_unlock(&ctx->usb_devs_lock);
576 /* Signal that an event has occurred for this device if we support hotplug AND
577 * the hotplug pipe is ready. This prevents an event from getting raised during
578 * initial enumeration. libusb_handle_events will take care of dereferencing the
580 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG) && dev->ctx->hotplug_pipe[1] > 0) {
581 ret = usbi_write(dev->ctx->hotplug_pipe[1], &message, sizeof(message));
582 if (sizeof(message) != ret) {
583 usbi_err(DEVICE_CTX(dev), "error writing hotplug message");
588 /* Perform some final sanity checks on a newly discovered device. If this
589 * function fails (negative return code), the device should not be added
590 * to the discovered device list. */
591 int usbi_sanitize_device(struct libusb_device *dev)
594 uint8_t num_configurations;
596 r = usbi_device_cache_descriptor(dev);
600 num_configurations = dev->device_descriptor.bNumConfigurations;
601 if (num_configurations > USB_MAXCONFIG) {
602 usbi_err(DEVICE_CTX(dev), "too many configurations");
603 return LIBUSB_ERROR_IO;
604 } else if (0 == num_configurations)
605 usbi_dbg("zero configurations, maybe an unauthorized device");
607 dev->num_configurations = num_configurations;
611 /* Examine libusb's internal list of known devices, looking for one with
612 * a specific session ID. Returns the matching device if it was found, and
614 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
615 unsigned long session_id)
617 struct libusb_device *dev;
618 struct libusb_device *ret = NULL;
620 usbi_mutex_lock(&ctx->usb_devs_lock);
621 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device)
622 if (dev->session_data == session_id) {
623 ret = libusb_ref_device(dev);
626 usbi_mutex_unlock(&ctx->usb_devs_lock);
632 * Returns a list of USB devices currently attached to the system. This is
633 * your entry point into finding a USB device to operate.
635 * You are expected to unreference all the devices when you are done with
636 * them, and then free the list with libusb_free_device_list(). Note that
637 * libusb_free_device_list() can unref all the devices for you. Be careful
638 * not to unreference a device you are about to open until after you have
641 * This return value of this function indicates the number of devices in
642 * the resultant list. The list is actually one element larger, as it is
645 * \param ctx the context to operate on, or NULL for the default context
646 * \param list output location for a list of devices. Must be later freed with
647 * libusb_free_device_list().
648 * \returns the number of devices in the outputted list, or any
649 * \ref libusb_error according to errors encountered by the backend.
651 ssize_t API_EXPORTED libusb_get_device_list(libusb_context *ctx,
652 libusb_device ***list)
654 struct discovered_devs *discdevs = discovered_devs_alloc();
655 struct libusb_device **ret;
658 USBI_GET_CONTEXT(ctx);
662 return LIBUSB_ERROR_NO_MEM;
664 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
665 /* backend provides hotplug support */
666 struct libusb_device *dev;
668 if (usbi_backend->hotplug_poll)
669 usbi_backend->hotplug_poll();
671 usbi_mutex_lock(&ctx->usb_devs_lock);
672 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device) {
673 discdevs = discovered_devs_append(discdevs, dev);
676 r = LIBUSB_ERROR_NO_MEM;
680 usbi_mutex_unlock(&ctx->usb_devs_lock);
682 /* backend does not provide hotplug support */
683 r = usbi_backend->get_device_list(ctx, &discdevs);
691 /* convert discovered_devs into a list */
693 ret = calloc(len + 1, sizeof(struct libusb_device *));
695 len = LIBUSB_ERROR_NO_MEM;
700 for (i = 0; i < len; i++) {
701 struct libusb_device *dev = discdevs->devices[i];
702 ret[i] = libusb_ref_device(dev);
707 discovered_devs_free(discdevs);
712 * Frees a list of devices previously discovered using
713 * libusb_get_device_list(). If the unref_devices parameter is set, the
714 * reference count of each device in the list is decremented by 1.
715 * \param list the list to free
716 * \param unref_devices whether to unref the devices in the list
718 void API_EXPORTED libusb_free_device_list(libusb_device **list,
726 struct libusb_device *dev;
728 while ((dev = list[i++]) != NULL)
729 libusb_unref_device(dev);
735 * Get the number of the bus that a device is connected to.
736 * \param dev a device
737 * \returns the bus number
739 uint8_t API_EXPORTED libusb_get_bus_number(libusb_device *dev)
741 return dev->bus_number;
745 * Get the number of the port that a device is connected to.
746 * Unless the OS does something funky, or you are hot-plugging USB extension cards,
747 * the port number returned by this call is usually guaranteed to be uniquely tied
748 * to a physical port, meaning that different devices plugged on the same physical
749 * port should return the same port number.
751 * But outside of this, there is no guarantee that the port number returned by this
752 * call will remain the same, or even match the order in which ports have been
753 * numbered by the HUB/HCD manufacturer.
755 * \param dev a device
756 * \returns the port number (0 if not available)
758 uint8_t API_EXPORTED libusb_get_port_number(libusb_device *dev)
760 return dev->port_number;
764 * Get the list of all port numbers from root for the specified device
766 * Since version 1.0.16, \ref LIBUSB_API_VERSION >= 0x01000102
767 * \param dev a device
768 * \param port_numbers the array that should contain the port numbers
769 * \param port_numbers_len the maximum length of the array. As per the USB 3.0
770 * specs, the current maximum limit for the depth is 7.
771 * \returns the number of elements filled
772 * \returns LIBUSB_ERROR_OVERFLOW if the array is too small
774 int API_EXPORTED libusb_get_port_numbers(libusb_device *dev,
775 uint8_t* port_numbers, int port_numbers_len)
777 int i = port_numbers_len;
778 struct libusb_context *ctx = DEVICE_CTX(dev);
780 if (port_numbers_len <= 0)
781 return LIBUSB_ERROR_INVALID_PARAM;
783 // HCDs can be listed as devices with port #0
784 while((dev) && (dev->port_number != 0)) {
786 usbi_warn(ctx, "port numbers array is too small");
787 return LIBUSB_ERROR_OVERFLOW;
789 port_numbers[i] = dev->port_number;
790 dev = dev->parent_dev;
792 if (i < port_numbers_len)
793 memmove(port_numbers, &port_numbers[i], port_numbers_len - i);
794 return port_numbers_len - i;
798 * Deprecated please use libusb_get_port_numbers instead.
800 int API_EXPORTED libusb_get_port_path(libusb_context *ctx, libusb_device *dev,
801 uint8_t* port_numbers, uint8_t port_numbers_len)
805 return libusb_get_port_numbers(dev, port_numbers, port_numbers_len);
809 * Get the the parent from the specified device.
810 * \param dev a device
811 * \returns the device parent or NULL if not available
812 * You should issue a \ref libusb_get_device_list() before calling this
813 * function and make sure that you only access the parent before issuing
814 * \ref libusb_free_device_list(). The reason is that libusb currently does
815 * not maintain a permanent list of device instances, and therefore can
816 * only guarantee that parents are fully instantiated within a
817 * libusb_get_device_list() - libusb_free_device_list() block.
820 libusb_device * LIBUSB_CALL libusb_get_parent(libusb_device *dev)
822 return dev->parent_dev;
826 * Get the address of the device on the bus it is connected to.
827 * \param dev a device
828 * \returns the device address
830 uint8_t API_EXPORTED libusb_get_device_address(libusb_device *dev)
832 return dev->device_address;
836 * Get the negotiated connection speed for a device.
837 * \param dev a device
838 * \returns a \ref libusb_speed code, where LIBUSB_SPEED_UNKNOWN means that
839 * the OS doesn't know or doesn't support returning the negotiated speed.
841 int API_EXPORTED libusb_get_device_speed(libusb_device *dev)
846 static const struct libusb_endpoint_descriptor *find_endpoint(
847 struct libusb_config_descriptor *config, unsigned char endpoint)
850 for (iface_idx = 0; iface_idx < config->bNumInterfaces; iface_idx++) {
851 const struct libusb_interface *iface = &config->interface[iface_idx];
854 for (altsetting_idx = 0; altsetting_idx < iface->num_altsetting;
856 const struct libusb_interface_descriptor *altsetting
857 = &iface->altsetting[altsetting_idx];
860 for (ep_idx = 0; ep_idx < altsetting->bNumEndpoints; ep_idx++) {
861 const struct libusb_endpoint_descriptor *ep =
862 &altsetting->endpoint[ep_idx];
863 if (ep->bEndpointAddress == endpoint)
872 * Convenience function to retrieve the wMaxPacketSize value for a particular
873 * endpoint in the active device configuration.
875 * This function was originally intended to be of assistance when setting up
876 * isochronous transfers, but a design mistake resulted in this function
877 * instead. It simply returns the wMaxPacketSize value without considering
878 * its contents. If you're dealing with isochronous transfers, you probably
879 * want libusb_get_max_iso_packet_size() instead.
881 * \param dev a device
882 * \param endpoint address of the endpoint in question
883 * \returns the wMaxPacketSize value
884 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
885 * \returns LIBUSB_ERROR_OTHER on other failure
887 int API_EXPORTED libusb_get_max_packet_size(libusb_device *dev,
888 unsigned char endpoint)
890 struct libusb_config_descriptor *config;
891 const struct libusb_endpoint_descriptor *ep;
894 r = libusb_get_active_config_descriptor(dev, &config);
896 usbi_err(DEVICE_CTX(dev),
897 "could not retrieve active config descriptor");
898 return LIBUSB_ERROR_OTHER;
901 ep = find_endpoint(config, endpoint);
903 r = LIBUSB_ERROR_NOT_FOUND;
907 r = ep->wMaxPacketSize;
910 libusb_free_config_descriptor(config);
915 * Calculate the maximum packet size which a specific endpoint is capable is
916 * sending or receiving in the duration of 1 microframe
918 * Only the active configuration is examined. The calculation is based on the
919 * wMaxPacketSize field in the endpoint descriptor as described in section
920 * 9.6.6 in the USB 2.0 specifications.
922 * If acting on an isochronous or interrupt endpoint, this function will
923 * multiply the value found in bits 0:10 by the number of transactions per
924 * microframe (determined by bits 11:12). Otherwise, this function just
925 * returns the numeric value found in bits 0:10.
927 * This function is useful for setting up isochronous transfers, for example
928 * you might pass the return value from this function to
929 * libusb_set_iso_packet_lengths() in order to set the length field of every
930 * isochronous packet in a transfer.
934 * \param dev a device
935 * \param endpoint address of the endpoint in question
936 * \returns the maximum packet size which can be sent/received on this endpoint
937 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
938 * \returns LIBUSB_ERROR_OTHER on other failure
940 int API_EXPORTED libusb_get_max_iso_packet_size(libusb_device *dev,
941 unsigned char endpoint)
943 struct libusb_config_descriptor *config;
944 const struct libusb_endpoint_descriptor *ep;
945 enum libusb_transfer_type ep_type;
949 r = libusb_get_active_config_descriptor(dev, &config);
951 usbi_err(DEVICE_CTX(dev),
952 "could not retrieve active config descriptor");
953 return LIBUSB_ERROR_OTHER;
956 ep = find_endpoint(config, endpoint);
958 r = LIBUSB_ERROR_NOT_FOUND;
962 val = ep->wMaxPacketSize;
963 ep_type = (enum libusb_transfer_type) (ep->bmAttributes & 0x3);
966 if (ep_type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
967 || ep_type == LIBUSB_TRANSFER_TYPE_INTERRUPT)
968 r *= (1 + ((val >> 11) & 3));
971 libusb_free_config_descriptor(config);
976 * Increment the reference count of a device.
977 * \param dev the device to reference
978 * \returns the same device
981 libusb_device * LIBUSB_CALL libusb_ref_device(libusb_device *dev)
983 usbi_mutex_lock(&dev->lock);
985 usbi_mutex_unlock(&dev->lock);
990 * Decrement the reference count of a device. If the decrement operation
991 * causes the reference count to reach zero, the device shall be destroyed.
992 * \param dev the device to unreference
994 void API_EXPORTED libusb_unref_device(libusb_device *dev)
1001 usbi_mutex_lock(&dev->lock);
1002 refcnt = --dev->refcnt;
1003 usbi_mutex_unlock(&dev->lock);
1006 usbi_dbg("destroy device %d.%d", dev->bus_number, dev->device_address);
1008 libusb_unref_device(dev->parent_dev);
1010 if (usbi_backend->destroy_device)
1011 usbi_backend->destroy_device(dev);
1013 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
1014 /* backend does not support hotplug */
1015 usbi_disconnect_device(dev);
1018 usbi_mutex_destroy(&dev->lock);
1024 * Interrupt the iteration of the event handling thread, so that it picks
1027 void usbi_fd_notification(struct libusb_context *ctx)
1029 unsigned char dummy = 1;
1035 /* record that we are messing with poll fds */
1036 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1037 ctx->pollfd_modify++;
1038 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1040 /* write some data on control pipe to interrupt event handlers */
1041 r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
1043 usbi_warn(ctx, "internal signalling write failed");
1044 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1045 ctx->pollfd_modify--;
1046 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1050 /* take event handling lock */
1051 libusb_lock_events(ctx);
1053 /* read the dummy data */
1054 r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
1056 usbi_warn(ctx, "internal signalling read failed");
1058 /* we're done with modifying poll fds */
1059 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1060 ctx->pollfd_modify--;
1061 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1063 /* Release event handling lock and wake up event waiters */
1064 libusb_unlock_events(ctx);
1068 * Open a device and obtain a device handle. A handle allows you to perform
1069 * I/O on the device in question.
1071 * Internally, this function adds a reference to the device and makes it
1072 * available to you through libusb_get_device(). This reference is removed
1073 * during libusb_close().
1075 * This is a non-blocking function; no requests are sent over the bus.
1077 * \param dev the device to open
1078 * \param handle output location for the returned device handle pointer. Only
1079 * populated when the return code is 0.
1080 * \returns 0 on success
1081 * \returns LIBUSB_ERROR_NO_MEM on memory allocation failure
1082 * \returns LIBUSB_ERROR_ACCESS if the user has insufficient permissions
1083 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1084 * \returns another LIBUSB_ERROR code on other failure
1086 int API_EXPORTED libusb_open(libusb_device *dev,
1087 libusb_device_handle **handle)
1089 struct libusb_context *ctx = DEVICE_CTX(dev);
1090 struct libusb_device_handle *_handle;
1091 size_t priv_size = usbi_backend->device_handle_priv_size;
1093 usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);
1095 if (!dev->attached) {
1096 return LIBUSB_ERROR_NO_DEVICE;
1099 _handle = malloc(sizeof(*_handle) + priv_size);
1101 return LIBUSB_ERROR_NO_MEM;
1103 r = usbi_mutex_init(&_handle->lock, NULL);
1106 return LIBUSB_ERROR_OTHER;
1109 _handle->dev = libusb_ref_device(dev);
1110 _handle->auto_detach_kernel_driver = 0;
1111 _handle->claimed_interfaces = 0;
1112 memset(&_handle->os_priv, 0, priv_size);
1114 r = usbi_backend->open(_handle);
1116 usbi_dbg("open %d.%d returns %d", dev->bus_number, dev->device_address, r);
1117 libusb_unref_device(dev);
1118 usbi_mutex_destroy(&_handle->lock);
1123 usbi_mutex_lock(&ctx->open_devs_lock);
1124 list_add(&_handle->list, &ctx->open_devs);
1125 usbi_mutex_unlock(&ctx->open_devs_lock);
1128 /* At this point, we want to interrupt any existing event handlers so
1129 * that they realise the addition of the new device's poll fd. One
1130 * example when this is desirable is if the user is running a separate
1131 * dedicated libusb events handling thread, which is running with a long
1132 * or infinite timeout. We want to interrupt that iteration of the loop,
1133 * so that it picks up the new fd, and then continues. */
1134 usbi_fd_notification(ctx);
1140 * Convenience function for finding a device with a particular
1141 * <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
1142 * for those scenarios where you are using libusb to knock up a quick test
1143 * application - it allows you to avoid calling libusb_get_device_list() and
1144 * worrying about traversing/freeing the list.
1146 * This function has limitations and is hence not intended for use in real
1147 * applications: if multiple devices have the same IDs it will only
1148 * give you the first one, etc.
1150 * \param ctx the context to operate on, or NULL for the default context
1151 * \param vendor_id the idVendor value to search for
1152 * \param product_id the idProduct value to search for
1153 * \returns a handle for the first found device, or NULL on error or if the
1154 * device could not be found. */
1156 libusb_device_handle * LIBUSB_CALL libusb_open_device_with_vid_pid(
1157 libusb_context *ctx, uint16_t vendor_id, uint16_t product_id)
1159 struct libusb_device **devs;
1160 struct libusb_device *found = NULL;
1161 struct libusb_device *dev;
1162 struct libusb_device_handle *handle = NULL;
1166 if (libusb_get_device_list(ctx, &devs) < 0)
1169 while ((dev = devs[i++]) != NULL) {
1170 struct libusb_device_descriptor desc;
1171 r = libusb_get_device_descriptor(dev, &desc);
1174 if (desc.idVendor == vendor_id && desc.idProduct == product_id) {
1181 r = libusb_open(found, &handle);
1187 libusb_free_device_list(devs, 1);
1191 static void do_close(struct libusb_context *ctx,
1192 struct libusb_device_handle *dev_handle)
1194 struct usbi_transfer *itransfer;
1195 struct usbi_transfer *tmp;
1197 libusb_lock_events(ctx);
1199 /* remove any transfers in flight that are for this device */
1200 usbi_mutex_lock(&ctx->flying_transfers_lock);
1202 /* safe iteration because transfers may be being deleted */
1203 list_for_each_entry_safe(itransfer, tmp, &ctx->flying_transfers, list, struct usbi_transfer) {
1204 struct libusb_transfer *transfer =
1205 USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
1207 if (transfer->dev_handle != dev_handle)
1210 if (!(itransfer->flags & USBI_TRANSFER_DEVICE_DISAPPEARED)) {
1211 usbi_err(ctx, "Device handle closed while transfer was still being processed, but the device is still connected as far as we know");
1213 if (itransfer->flags & USBI_TRANSFER_CANCELLING)
1214 usbi_warn(ctx, "A cancellation for an in-flight transfer hasn't completed but closing the device handle");
1216 usbi_err(ctx, "A cancellation hasn't even been scheduled on the transfer for which the device is closing");
1219 /* remove from the list of in-flight transfers and make sure
1220 * we don't accidentally use the device handle in the future
1221 * (or that such accesses will be easily caught and identified as a crash)
1223 usbi_mutex_lock(&itransfer->lock);
1224 list_del(&itransfer->list);
1225 transfer->dev_handle = NULL;
1226 usbi_mutex_unlock(&itransfer->lock);
1228 /* it is up to the user to free up the actual transfer struct. this is
1229 * just making sure that we don't attempt to process the transfer after
1230 * the device handle is invalid
1232 usbi_dbg("Removed transfer %p from the in-flight list because device handle %p closed",
1233 transfer, dev_handle);
1235 usbi_mutex_unlock(&ctx->flying_transfers_lock);
1237 libusb_unlock_events(ctx);
1239 usbi_mutex_lock(&ctx->open_devs_lock);
1240 list_del(&dev_handle->list);
1241 usbi_mutex_unlock(&ctx->open_devs_lock);
1243 usbi_backend->close(dev_handle);
1244 libusb_unref_device(dev_handle->dev);
1245 usbi_mutex_destroy(&dev_handle->lock);
1250 * Close a device handle. Should be called on all open handles before your
1251 * application exits.
1253 * Internally, this function destroys the reference that was added by
1254 * libusb_open() on the given device.
1256 * This is a non-blocking function; no requests are sent over the bus.
1258 * \param dev_handle the handle to close
1260 void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
1262 struct libusb_context *ctx;
1263 unsigned char dummy = 1;
1270 ctx = HANDLE_CTX(dev_handle);
1272 /* Similarly to libusb_open(), we want to interrupt all event handlers
1273 * at this point. More importantly, we want to perform the actual close of
1274 * the device while holding the event handling lock (preventing any other
1275 * thread from doing event handling) because we will be removing a file
1276 * descriptor from the polling loop. */
1278 /* record that we are messing with poll fds */
1279 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1280 ctx->pollfd_modify++;
1281 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1283 /* write some data on control pipe to interrupt event handlers */
1284 r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
1286 usbi_warn(ctx, "internal signalling write failed, closing anyway");
1287 do_close(ctx, dev_handle);
1288 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1289 ctx->pollfd_modify--;
1290 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1294 /* take event handling lock */
1295 libusb_lock_events(ctx);
1297 /* read the dummy data */
1298 r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
1300 usbi_warn(ctx, "internal signalling read failed, closing anyway");
1302 /* Close the device */
1303 do_close(ctx, dev_handle);
1305 /* we're done with modifying poll fds */
1306 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1307 ctx->pollfd_modify--;
1308 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1310 /* Release event handling lock and wake up event waiters */
1311 libusb_unlock_events(ctx);
1315 * Get the underlying device for a handle. This function does not modify
1316 * the reference count of the returned device, so do not feel compelled to
1317 * unreference it when you are done.
1318 * \param dev_handle a device handle
1319 * \returns the underlying device
1322 libusb_device * LIBUSB_CALL libusb_get_device(libusb_device_handle *dev_handle)
1324 return dev_handle->dev;
1328 * Determine the bConfigurationValue of the currently active configuration.
1330 * You could formulate your own control request to obtain this information,
1331 * but this function has the advantage that it may be able to retrieve the
1332 * information from operating system caches (no I/O involved).
1334 * If the OS does not cache this information, then this function will block
1335 * while a control transfer is submitted to retrieve the information.
1337 * This function will return a value of 0 in the <tt>config</tt> output
1338 * parameter if the device is in unconfigured state.
1340 * \param dev a device handle
1341 * \param config output location for the bConfigurationValue of the active
1342 * configuration (only valid for return code 0)
1343 * \returns 0 on success
1344 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1345 * \returns another LIBUSB_ERROR code on other failure
1347 int API_EXPORTED libusb_get_configuration(libusb_device_handle *dev,
1350 int r = LIBUSB_ERROR_NOT_SUPPORTED;
1353 if (usbi_backend->get_configuration)
1354 r = usbi_backend->get_configuration(dev, config);
1356 if (r == LIBUSB_ERROR_NOT_SUPPORTED) {
1358 usbi_dbg("falling back to control message");
1359 r = libusb_control_transfer(dev, LIBUSB_ENDPOINT_IN,
1360 LIBUSB_REQUEST_GET_CONFIGURATION, 0, 0, &tmp, 1, 1000);
1362 usbi_err(HANDLE_CTX(dev), "zero bytes returned in ctrl transfer?");
1363 r = LIBUSB_ERROR_IO;
1364 } else if (r == 1) {
1368 usbi_dbg("control failed, error %d", r);
1373 usbi_dbg("active config %d", *config);
1379 * Set the active configuration for a device.
1381 * The operating system may or may not have already set an active
1382 * configuration on the device. It is up to your application to ensure the
1383 * correct configuration is selected before you attempt to claim interfaces
1384 * and perform other operations.
1386 * If you call this function on a device already configured with the selected
1387 * configuration, then this function will act as a lightweight device reset:
1388 * it will issue a SET_CONFIGURATION request using the current configuration,
1389 * causing most USB-related device state to be reset (altsetting reset to zero,
1390 * endpoint halts cleared, toggles reset).
1392 * You cannot change/reset configuration if your application has claimed
1393 * interfaces. It is advised to set the desired configuration before claiming
1396 * Alternatively you can call libusb_release_interface() first. Note if you
1397 * do things this way you must ensure that auto_detach_kernel_driver for
1398 * <tt>dev</tt> is 0, otherwise the kernel driver will be re-attached when you
1399 * release the interface(s).
1401 * You cannot change/reset configuration if other applications or drivers have
1402 * claimed interfaces.
1404 * A configuration value of -1 will put the device in unconfigured state.
1405 * The USB specifications state that a configuration value of 0 does this,
1406 * however buggy devices exist which actually have a configuration 0.
1408 * You should always use this function rather than formulating your own
1409 * SET_CONFIGURATION control request. This is because the underlying operating
1410 * system needs to know when such changes happen.
1412 * This is a blocking function.
1414 * \param dev a device handle
1415 * \param configuration the bConfigurationValue of the configuration you
1416 * wish to activate, or -1 if you wish to put the device in unconfigured state
1417 * \returns 0 on success
1418 * \returns LIBUSB_ERROR_NOT_FOUND if the requested configuration does not exist
1419 * \returns LIBUSB_ERROR_BUSY if interfaces are currently claimed
1420 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1421 * \returns another LIBUSB_ERROR code on other failure
1422 * \see libusb_set_auto_detach_kernel_driver()
1424 int API_EXPORTED libusb_set_configuration(libusb_device_handle *dev,
1427 usbi_dbg("configuration %d", configuration);
1428 return usbi_backend->set_configuration(dev, configuration);
1432 * Claim an interface on a given device handle. You must claim the interface
1433 * you wish to use before you can perform I/O on any of its endpoints.
1435 * It is legal to attempt to claim an already-claimed interface, in which
1436 * case libusb just returns 0 without doing anything.
1438 * If auto_detach_kernel_driver is set to 1 for <tt>dev</tt>, the kernel driver
1439 * will be detached if necessary, on failure the detach error is returned.
1441 * Claiming of interfaces is a purely logical operation; it does not cause
1442 * any requests to be sent over the bus. Interface claiming is used to
1443 * instruct the underlying operating system that your application wishes
1444 * to take ownership of the interface.
1446 * This is a non-blocking function.
1448 * \param dev a device handle
1449 * \param interface_number the <tt>bInterfaceNumber</tt> of the interface you
1451 * \returns 0 on success
1452 * \returns LIBUSB_ERROR_NOT_FOUND if the requested interface does not exist
1453 * \returns LIBUSB_ERROR_BUSY if another program or driver has claimed the
1455 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1456 * \returns a LIBUSB_ERROR code on other failure
1457 * \see libusb_set_auto_detach_kernel_driver()
1459 int API_EXPORTED libusb_claim_interface(libusb_device_handle *dev,
1460 int interface_number)
1464 usbi_dbg("interface %d", interface_number);
1465 if (interface_number >= USB_MAXINTERFACES)
1466 return LIBUSB_ERROR_INVALID_PARAM;
1468 if (!dev->dev->attached)
1469 return LIBUSB_ERROR_NO_DEVICE;
1471 usbi_mutex_lock(&dev->lock);
1472 if (dev->claimed_interfaces & (1 << interface_number))
1475 r = usbi_backend->claim_interface(dev, interface_number);
1477 dev->claimed_interfaces |= 1 << interface_number;
1480 usbi_mutex_unlock(&dev->lock);
1485 * Release an interface previously claimed with libusb_claim_interface(). You
1486 * should release all claimed interfaces before closing a device handle.
1488 * This is a blocking function. A SET_INTERFACE control request will be sent
1489 * to the device, resetting interface state to the first alternate setting.
1491 * If auto_detach_kernel_driver is set to 1 for <tt>dev</tt>, the kernel
1492 * driver will be re-attached after releasing the interface.
1494 * \param dev a device handle
1495 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1496 * previously-claimed interface
1497 * \returns 0 on success
1498 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed
1499 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1500 * \returns another LIBUSB_ERROR code on other failure
1501 * \see libusb_set_auto_detach_kernel_driver()
1503 int API_EXPORTED libusb_release_interface(libusb_device_handle *dev,
1504 int interface_number)
1508 usbi_dbg("interface %d", interface_number);
1509 if (interface_number >= USB_MAXINTERFACES)
1510 return LIBUSB_ERROR_INVALID_PARAM;
1512 usbi_mutex_lock(&dev->lock);
1513 if (!(dev->claimed_interfaces & (1 << interface_number))) {
1514 r = LIBUSB_ERROR_NOT_FOUND;
1518 r = usbi_backend->release_interface(dev, interface_number);
1520 dev->claimed_interfaces &= ~(1 << interface_number);
1523 usbi_mutex_unlock(&dev->lock);
1528 * Activate an alternate setting for an interface. The interface must have
1529 * been previously claimed with libusb_claim_interface().
1531 * You should always use this function rather than formulating your own
1532 * SET_INTERFACE control request. This is because the underlying operating
1533 * system needs to know when such changes happen.
1535 * This is a blocking function.
1537 * \param dev a device handle
1538 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1539 * previously-claimed interface
1540 * \param alternate_setting the <tt>bAlternateSetting</tt> of the alternate
1541 * setting to activate
1542 * \returns 0 on success
1543 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed, or the
1544 * requested alternate setting does not exist
1545 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1546 * \returns another LIBUSB_ERROR code on other failure
1548 int API_EXPORTED libusb_set_interface_alt_setting(libusb_device_handle *dev,
1549 int interface_number, int alternate_setting)
1551 usbi_dbg("interface %d altsetting %d",
1552 interface_number, alternate_setting);
1553 if (interface_number >= USB_MAXINTERFACES)
1554 return LIBUSB_ERROR_INVALID_PARAM;
1556 usbi_mutex_lock(&dev->lock);
1557 if (!dev->dev->attached) {
1558 usbi_mutex_unlock(&dev->lock);
1559 return LIBUSB_ERROR_NO_DEVICE;
1562 if (!(dev->claimed_interfaces & (1 << interface_number))) {
1563 usbi_mutex_unlock(&dev->lock);
1564 return LIBUSB_ERROR_NOT_FOUND;
1566 usbi_mutex_unlock(&dev->lock);
1568 return usbi_backend->set_interface_altsetting(dev, interface_number,
1573 * Clear the halt/stall condition for an endpoint. Endpoints with halt status
1574 * are unable to receive or transmit data until the halt condition is stalled.
1576 * You should cancel all pending transfers before attempting to clear the halt
1579 * This is a blocking function.
1581 * \param dev a device handle
1582 * \param endpoint the endpoint to clear halt status
1583 * \returns 0 on success
1584 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
1585 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1586 * \returns another LIBUSB_ERROR code on other failure
1588 int API_EXPORTED libusb_clear_halt(libusb_device_handle *dev,
1589 unsigned char endpoint)
1591 usbi_dbg("endpoint %x", endpoint);
1592 if (!dev->dev->attached)
1593 return LIBUSB_ERROR_NO_DEVICE;
1595 return usbi_backend->clear_halt(dev, endpoint);
1599 * Perform a USB port reset to reinitialize a device. The system will attempt
1600 * to restore the previous configuration and alternate settings after the
1601 * reset has completed.
1603 * If the reset fails, the descriptors change, or the previous state cannot be
1604 * restored, the device will appear to be disconnected and reconnected. This
1605 * means that the device handle is no longer valid (you should close it) and
1606 * rediscover the device. A return code of LIBUSB_ERROR_NOT_FOUND indicates
1607 * when this is the case.
1609 * This is a blocking function which usually incurs a noticeable delay.
1611 * \param dev a handle of the device to reset
1612 * \returns 0 on success
1613 * \returns LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the
1614 * device has been disconnected
1615 * \returns another LIBUSB_ERROR code on other failure
1617 int API_EXPORTED libusb_reset_device(libusb_device_handle *dev)
1620 if (!dev->dev->attached)
1621 return LIBUSB_ERROR_NO_DEVICE;
1623 return usbi_backend->reset_device(dev);
1626 /** \ingroup asyncio
1627 * Allocate up to num_streams usb bulk streams on the specified endpoints. This
1628 * function takes an array of endpoints rather then a single endpoint because
1629 * some protocols require that endpoints are setup with similar stream ids.
1630 * All endpoints passed in must belong to the same interface.
1632 * Note this function may return less streams then requested. Also note that the
1633 * same number of streams are allocated for each endpoint in the endpoint array.
1635 * Stream id 0 is reserved, and should not be used to communicate with devices.
1636 * If libusb_alloc_streams() returns with a value of N, you may use stream ids
1639 * Since version 1.0.19, \ref LIBUSB_API_VERSION >= 0x01000103
1641 * \param dev a device handle
1642 * \param num_streams number of streams to try to allocate
1643 * \param endpoints array of endpoints to allocate streams on
1644 * \param num_endpoints length of the endpoints array
1645 * \returns number of streams allocated, or a LIBUSB_ERROR code on failure
1647 int API_EXPORTED libusb_alloc_streams(libusb_device_handle *dev,
1648 uint32_t num_streams, unsigned char *endpoints, int num_endpoints)
1650 usbi_dbg("streams %u eps %d", (unsigned) num_streams, num_endpoints);
1652 if (!dev->dev->attached)
1653 return LIBUSB_ERROR_NO_DEVICE;
1655 if (usbi_backend->alloc_streams)
1656 return usbi_backend->alloc_streams(dev, num_streams, endpoints,
1659 return LIBUSB_ERROR_NOT_SUPPORTED;
1662 /** \ingroup asyncio
1663 * Free usb bulk streams allocated with libusb_alloc_streams().
1665 * Note streams are automatically free-ed when releasing an interface.
1667 * Since version 1.0.19, \ref LIBUSB_API_VERSION >= 0x01000103
1669 * \param dev a device handle
1670 * \param endpoints array of endpoints to free streams on
1671 * \param num_endpoints length of the endpoints array
1672 * \returns LIBUSB_SUCCESS, or a LIBUSB_ERROR code on failure
1674 int API_EXPORTED libusb_free_streams(libusb_device_handle *dev,
1675 unsigned char *endpoints, int num_endpoints)
1677 usbi_dbg("eps %d", num_endpoints);
1679 if (!dev->dev->attached)
1680 return LIBUSB_ERROR_NO_DEVICE;
1682 if (usbi_backend->free_streams)
1683 return usbi_backend->free_streams(dev, endpoints,
1686 return LIBUSB_ERROR_NOT_SUPPORTED;
1690 * Determine if a kernel driver is active on an interface. If a kernel driver
1691 * is active, you cannot claim the interface, and libusb will be unable to
1694 * This functionality is not available on Windows.
1696 * \param dev a device handle
1697 * \param interface_number the interface to check
1698 * \returns 0 if no kernel driver is active
1699 * \returns 1 if a kernel driver is active
1700 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1701 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1703 * \returns another LIBUSB_ERROR code on other failure
1704 * \see libusb_detach_kernel_driver()
1706 int API_EXPORTED libusb_kernel_driver_active(libusb_device_handle *dev,
1707 int interface_number)
1709 usbi_dbg("interface %d", interface_number);
1711 if (!dev->dev->attached)
1712 return LIBUSB_ERROR_NO_DEVICE;
1714 if (usbi_backend->kernel_driver_active)
1715 return usbi_backend->kernel_driver_active(dev, interface_number);
1717 return LIBUSB_ERROR_NOT_SUPPORTED;
1721 * Detach a kernel driver from an interface. If successful, you will then be
1722 * able to claim the interface and perform I/O.
1724 * This functionality is not available on Darwin or Windows.
1726 * Note that libusb itself also talks to the device through a special kernel
1727 * driver, if this driver is already attached to the device, this call will
1728 * not detach it and return LIBUSB_ERROR_NOT_FOUND.
1730 * \param dev a device handle
1731 * \param interface_number the interface to detach the driver from
1732 * \returns 0 on success
1733 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1734 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1735 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1736 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1738 * \returns another LIBUSB_ERROR code on other failure
1739 * \see libusb_kernel_driver_active()
1741 int API_EXPORTED libusb_detach_kernel_driver(libusb_device_handle *dev,
1742 int interface_number)
1744 usbi_dbg("interface %d", interface_number);
1746 if (!dev->dev->attached)
1747 return LIBUSB_ERROR_NO_DEVICE;
1749 if (usbi_backend->detach_kernel_driver)
1750 return usbi_backend->detach_kernel_driver(dev, interface_number);
1752 return LIBUSB_ERROR_NOT_SUPPORTED;
1756 * Re-attach an interface's kernel driver, which was previously detached
1757 * using libusb_detach_kernel_driver(). This call is only effective on
1758 * Linux and returns LIBUSB_ERROR_NOT_SUPPORTED on all other platforms.
1760 * This functionality is not available on Darwin or Windows.
1762 * \param dev a device handle
1763 * \param interface_number the interface to attach the driver from
1764 * \returns 0 on success
1765 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1766 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1767 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1768 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1770 * \returns LIBUSB_ERROR_BUSY if the driver cannot be attached because the
1771 * interface is claimed by a program or driver
1772 * \returns another LIBUSB_ERROR code on other failure
1773 * \see libusb_kernel_driver_active()
1775 int API_EXPORTED libusb_attach_kernel_driver(libusb_device_handle *dev,
1776 int interface_number)
1778 usbi_dbg("interface %d", interface_number);
1780 if (!dev->dev->attached)
1781 return LIBUSB_ERROR_NO_DEVICE;
1783 if (usbi_backend->attach_kernel_driver)
1784 return usbi_backend->attach_kernel_driver(dev, interface_number);
1786 return LIBUSB_ERROR_NOT_SUPPORTED;
1790 * Enable/disable libusb's automatic kernel driver detachment. When this is
1791 * enabled libusb will automatically detach the kernel driver on an interface
1792 * when claiming the interface, and attach it when releasing the interface.
1794 * Automatic kernel driver detachment is disabled on newly opened device
1795 * handles by default.
1797 * On platforms which do not have LIBUSB_CAP_SUPPORTS_DETACH_KERNEL_DRIVER
1798 * this function will return LIBUSB_ERROR_NOT_SUPPORTED, and libusb will
1799 * continue as if this function was never called.
1801 * \param dev a device handle
1802 * \param enable whether to enable or disable auto kernel driver detachment
1804 * \returns LIBUSB_SUCCESS on success
1805 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1807 * \see libusb_claim_interface()
1808 * \see libusb_release_interface()
1809 * \see libusb_set_configuration()
1811 int API_EXPORTED libusb_set_auto_detach_kernel_driver(
1812 libusb_device_handle *dev, int enable)
1814 if (!(usbi_backend->caps & USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER))
1815 return LIBUSB_ERROR_NOT_SUPPORTED;
1817 dev->auto_detach_kernel_driver = enable;
1818 return LIBUSB_SUCCESS;
1822 * Set log message verbosity.
1824 * The default level is LIBUSB_LOG_LEVEL_NONE, which means no messages are ever
1825 * printed. If you choose to increase the message verbosity level, ensure
1826 * that your application does not close the stdout/stderr file descriptors.
1828 * You are advised to use level LIBUSB_LOG_LEVEL_WARNING. libusb is conservative
1829 * with its message logging and most of the time, will only log messages that
1830 * explain error conditions and other oddities. This will help you debug
1833 * If the LIBUSB_DEBUG environment variable was set when libusb was
1834 * initialized, this function does nothing: the message verbosity is fixed
1835 * to the value in the environment variable.
1837 * If libusb was compiled without any message logging, this function does
1838 * nothing: you'll never get any messages.
1840 * If libusb was compiled with verbose debug message logging, this function
1841 * does nothing: you'll always get messages from all levels.
1843 * \param ctx the context to operate on, or NULL for the default context
1844 * \param level debug level to set
1846 void API_EXPORTED libusb_set_debug(libusb_context *ctx, int level)
1848 USBI_GET_CONTEXT(ctx);
1849 if (!ctx->debug_fixed)
1854 * Initialize libusb. This function must be called before calling any other
1857 * If you do not provide an output location for a context pointer, a default
1858 * context will be created. If there was already a default context, it will
1859 * be reused (and nothing will be initialized/reinitialized).
1861 * \param context Optional output location for context pointer.
1862 * Only valid on return code 0.
1863 * \returns 0 on success, or a LIBUSB_ERROR code on failure
1866 int API_EXPORTED libusb_init(libusb_context **context)
1868 struct libusb_device *dev, *next;
1869 char *dbg = getenv("LIBUSB_DEBUG");
1870 struct libusb_context *ctx;
1871 static int first_init = 1;
1874 usbi_mutex_static_lock(&default_context_lock);
1876 if (!timestamp_origin.tv_sec) {
1877 usbi_gettimeofday(×tamp_origin, NULL);
1880 if (!context && usbi_default_context) {
1881 usbi_dbg("reusing default context");
1882 default_context_refcnt++;
1883 usbi_mutex_static_unlock(&default_context_lock);
1887 ctx = calloc(1, sizeof(*ctx));
1889 r = LIBUSB_ERROR_NO_MEM;
1893 #ifdef ENABLE_DEBUG_LOGGING
1894 ctx->debug = LIBUSB_LOG_LEVEL_DEBUG;
1898 ctx->debug = atoi(dbg);
1900 ctx->debug_fixed = 1;
1903 /* default context should be initialized before calling usbi_dbg */
1904 if (!usbi_default_context) {
1905 usbi_default_context = ctx;
1906 default_context_refcnt++;
1907 usbi_dbg("created default context");
1910 usbi_dbg("libusb v%d.%d.%d.%d", libusb_version_internal.major, libusb_version_internal.minor,
1911 libusb_version_internal.micro, libusb_version_internal.nano);
1913 usbi_mutex_init(&ctx->usb_devs_lock, NULL);
1914 usbi_mutex_init(&ctx->open_devs_lock, NULL);
1915 usbi_mutex_init(&ctx->hotplug_cbs_lock, NULL);
1916 list_init(&ctx->usb_devs);
1917 list_init(&ctx->open_devs);
1918 list_init(&ctx->hotplug_cbs);
1920 usbi_mutex_static_lock(&active_contexts_lock);
1923 list_init (&active_contexts_list);
1925 list_add (&ctx->list, &active_contexts_list);
1926 usbi_mutex_static_unlock(&active_contexts_lock);
1928 if (usbi_backend->init) {
1929 r = usbi_backend->init(ctx);
1934 r = usbi_io_init(ctx);
1936 goto err_backend_exit;
1938 usbi_mutex_static_unlock(&default_context_lock);
1946 if (usbi_backend->exit)
1947 usbi_backend->exit();
1949 if (ctx == usbi_default_context)
1950 usbi_default_context = NULL;
1952 usbi_mutex_static_lock(&active_contexts_lock);
1953 list_del (&ctx->list);
1954 usbi_mutex_static_unlock(&active_contexts_lock);
1956 usbi_mutex_lock(&ctx->usb_devs_lock);
1957 list_for_each_entry_safe(dev, next, &ctx->usb_devs, list, struct libusb_device) {
1958 list_del(&dev->list);
1959 libusb_unref_device(dev);
1961 usbi_mutex_unlock(&ctx->usb_devs_lock);
1963 usbi_mutex_destroy(&ctx->open_devs_lock);
1964 usbi_mutex_destroy(&ctx->usb_devs_lock);
1965 usbi_mutex_destroy(&ctx->hotplug_cbs_lock);
1969 usbi_mutex_static_unlock(&default_context_lock);
1974 * Deinitialize libusb. Should be called after closing all open devices and
1975 * before your application terminates.
1976 * \param ctx the context to deinitialize, or NULL for the default context
1978 void API_EXPORTED libusb_exit(struct libusb_context *ctx)
1980 struct libusb_device *dev, *next;
1981 struct timeval tv = { 0, 0 };
1984 USBI_GET_CONTEXT(ctx);
1986 /* if working with default context, only actually do the deinitialization
1987 * if we're the last user */
1988 usbi_mutex_static_lock(&default_context_lock);
1989 if (ctx == usbi_default_context) {
1990 if (--default_context_refcnt > 0) {
1991 usbi_dbg("not destroying default context");
1992 usbi_mutex_static_unlock(&default_context_lock);
1995 usbi_dbg("destroying default context");
1996 usbi_default_context = NULL;
1998 usbi_mutex_static_unlock(&default_context_lock);
2000 usbi_mutex_static_lock(&active_contexts_lock);
2001 list_del (&ctx->list);
2002 usbi_mutex_static_unlock(&active_contexts_lock);
2004 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
2005 usbi_hotplug_deregister_all(ctx);
2008 * Ensure any pending unplug events are read from the hotplug
2009 * pipe. The usb_device-s hold in the events are no longer part
2010 * of usb_devs, but the events still hold a reference!
2012 * Note we don't do this if the application has left devices
2013 * open (which implies a buggy app) to avoid packet completion
2014 * handlers running when the app does not expect them to run.
2016 if (list_empty(&ctx->open_devs))
2017 libusb_handle_events_timeout(ctx, &tv);
2019 usbi_mutex_lock(&ctx->usb_devs_lock);
2020 list_for_each_entry_safe(dev, next, &ctx->usb_devs, list, struct libusb_device) {
2021 list_del(&dev->list);
2022 libusb_unref_device(dev);
2024 usbi_mutex_unlock(&ctx->usb_devs_lock);
2027 /* a few sanity checks. don't bother with locking because unless
2028 * there is an application bug, nobody will be accessing these. */
2029 if (!list_empty(&ctx->usb_devs))
2030 usbi_warn(ctx, "some libusb_devices were leaked");
2031 if (!list_empty(&ctx->open_devs))
2032 usbi_warn(ctx, "application left some devices open");
2035 if (usbi_backend->exit)
2036 usbi_backend->exit();
2038 usbi_mutex_destroy(&ctx->open_devs_lock);
2039 usbi_mutex_destroy(&ctx->usb_devs_lock);
2040 usbi_mutex_destroy(&ctx->hotplug_cbs_lock);
2045 * Check at runtime if the loaded library has a given capability.
2046 * This call should be performed after \ref libusb_init(), to ensure the
2047 * backend has updated its capability set.
2049 * \param capability the \ref libusb_capability to check for
2050 * \returns nonzero if the running library has the capability, 0 otherwise
2052 int API_EXPORTED libusb_has_capability(uint32_t capability)
2054 switch (capability) {
2055 case LIBUSB_CAP_HAS_CAPABILITY:
2057 case LIBUSB_CAP_HAS_HOTPLUG:
2058 return !(usbi_backend->get_device_list);
2059 case LIBUSB_CAP_HAS_HID_ACCESS:
2060 return (usbi_backend->caps & USBI_CAP_HAS_HID_ACCESS);
2061 case LIBUSB_CAP_SUPPORTS_DETACH_KERNEL_DRIVER:
2062 return (usbi_backend->caps & USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER);
2067 /* this is defined in libusbi.h if needed */
2068 #ifdef LIBUSB_GETTIMEOFDAY_WIN32
2071 * Implementation according to:
2072 * The Open Group Base Specifications Issue 6
2073 * IEEE Std 1003.1, 2004 Edition
2077 * THIS SOFTWARE IS NOT COPYRIGHTED
2079 * This source code is offered for use in the public domain. You may
2080 * use, modify or distribute it freely.
2082 * This code is distributed in the hope that it will be useful but
2083 * WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
2084 * DISCLAIMED. This includes but is not limited to warranties of
2085 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
2088 * Danny Smith <dannysmith@users.sourceforge.net>
2091 /* Offset between 1/1/1601 and 1/1/1970 in 100 nanosec units */
2092 #define _W32_FT_OFFSET (116444736000000000)
2094 int usbi_gettimeofday(struct timeval *tp, void *tzp)
2097 unsigned __int64 ns100; /* Time since 1 Jan 1601, in 100ns units */
2103 #if defined(OS_WINCE)
2106 SystemTimeToFileTime(&st, &_now.ft);
2108 GetSystemTimeAsFileTime (&_now.ft);
2110 tp->tv_usec=(long)((_now.ns100 / 10) % 1000000 );
2111 tp->tv_sec= (long)((_now.ns100 - _W32_FT_OFFSET) / 10000000);
2113 /* Always return 0 as per Open Group Base Specifications Issue 6.
2114 Do not set errno on error. */
2119 static void usbi_log_str(struct libusb_context *ctx,
2120 enum libusb_log_level level, const char * str)
2122 #if defined(USE_SYSTEM_LOGGING_FACILITY)
2123 #if defined(OS_WINDOWS) || defined(OS_WINCE)
2124 /* Windows CE only supports the Unicode version of OutputDebugString. */
2125 WCHAR wbuf[USBI_MAX_LOG_LEN];
2126 MultiByteToWideChar(CP_UTF8, 0, str, -1, wbuf, sizeof(wbuf));
2127 OutputDebugStringW(wbuf);
2128 #elif defined(__ANDROID__)
2129 int priority = ANDROID_LOG_UNKNOWN;
2131 case LIBUSB_LOG_LEVEL_INFO: priority = ANDROID_LOG_INFO; break;
2132 case LIBUSB_LOG_LEVEL_WARNING: priority = ANDROID_LOG_WARN; break;
2133 case LIBUSB_LOG_LEVEL_ERROR: priority = ANDROID_LOG_ERROR; break;
2134 case LIBUSB_LOG_LEVEL_DEBUG: priority = ANDROID_LOG_DEBUG; break;
2136 __android_log_write(priority, "libusb", str);
2137 #elif defined(HAVE_SYSLOG_FUNC)
2138 int syslog_level = LOG_INFO;
2140 case LIBUSB_LOG_LEVEL_INFO: syslog_level = LOG_INFO; break;
2141 case LIBUSB_LOG_LEVEL_WARNING: syslog_level = LOG_WARNING; break;
2142 case LIBUSB_LOG_LEVEL_ERROR: syslog_level = LOG_ERR; break;
2143 case LIBUSB_LOG_LEVEL_DEBUG: syslog_level = LOG_DEBUG; break;
2145 syslog(syslog_level, "%s", str);
2146 #else /* All of gcc, Clang, XCode seem to use #warning */
2147 #warning System logging is not supported on this platform. Logging to stderr will be used instead.
2152 #endif /* USE_SYSTEM_LOGGING_FACILITY */
2157 void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
2158 const char *function, const char *format, va_list args)
2160 const char *prefix = "";
2161 char buf[USBI_MAX_LOG_LEN];
2163 int global_debug, header_len, text_len;
2164 static int has_debug_header_been_displayed = 0;
2166 #ifdef ENABLE_DEBUG_LOGGING
2172 USBI_GET_CONTEXT(ctx);
2174 ctx_level = ctx->debug;
2176 char *dbg = getenv("LIBUSB_DEBUG");
2178 ctx_level = atoi(dbg);
2180 global_debug = (ctx_level == LIBUSB_LOG_LEVEL_DEBUG);
2183 if (level == LIBUSB_LOG_LEVEL_WARNING && ctx_level < LIBUSB_LOG_LEVEL_WARNING)
2185 if (level == LIBUSB_LOG_LEVEL_INFO && ctx_level < LIBUSB_LOG_LEVEL_INFO)
2187 if (level == LIBUSB_LOG_LEVEL_DEBUG && ctx_level < LIBUSB_LOG_LEVEL_DEBUG)
2191 usbi_gettimeofday(&now, NULL);
2192 if ((global_debug) && (!has_debug_header_been_displayed)) {
2193 has_debug_header_been_displayed = 1;
2194 usbi_log_str(ctx, LIBUSB_LOG_LEVEL_DEBUG, "[timestamp] [threadID] facility level [function call] <message>\n");
2195 usbi_log_str(ctx, LIBUSB_LOG_LEVEL_DEBUG, "--------------------------------------------------------------------------------\n");
2197 if (now.tv_usec < timestamp_origin.tv_usec) {
2199 now.tv_usec += 1000000;
2201 now.tv_sec -= timestamp_origin.tv_sec;
2202 now.tv_usec -= timestamp_origin.tv_usec;
2205 case LIBUSB_LOG_LEVEL_INFO:
2208 case LIBUSB_LOG_LEVEL_WARNING:
2211 case LIBUSB_LOG_LEVEL_ERROR:
2214 case LIBUSB_LOG_LEVEL_DEBUG:
2217 case LIBUSB_LOG_LEVEL_NONE:
2225 header_len = snprintf(buf, sizeof(buf),
2226 "[%2d.%06d] [%08x] libusb: %s [%s] ",
2227 (int)now.tv_sec, (int)now.tv_usec, usbi_get_tid(), prefix, function);
2229 header_len = snprintf(buf, sizeof(buf),
2230 "libusb: %s [%s] ", prefix, function);
2233 if (header_len < 0 || header_len >= sizeof(buf)) {
2234 /* Somehow snprintf failed to write to the buffer,
2235 * remove the header so something useful is output. */
2238 /* Make sure buffer is NUL terminated */
2239 buf[header_len] = '\0';
2240 text_len = vsnprintf(buf + header_len, sizeof(buf) - header_len,
2242 if (text_len < 0 || text_len + header_len >= sizeof(buf)) {
2243 /* Truncated log output. On some platforms a -1 return value means
2244 * that the output was truncated. */
2245 text_len = sizeof(buf) - header_len;
2247 if (header_len + text_len + sizeof(USBI_LOG_LINE_END) >= sizeof(buf)) {
2248 /* Need to truncate the text slightly to fit on the terminator. */
2249 text_len -= (header_len + text_len + sizeof(USBI_LOG_LINE_END)) - sizeof(buf);
2251 strcpy(buf + header_len + text_len, USBI_LOG_LINE_END);
2253 usbi_log_str(ctx, level, buf);
2256 void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
2257 const char *function, const char *format, ...)
2261 va_start (args, format);
2262 usbi_log_v(ctx, level, function, format, args);
2267 * Returns a constant NULL-terminated string with the ASCII name of a libusb
2268 * error or transfer status code. The caller must not free() the returned
2271 * \param error_code The \ref libusb_error or libusb_transfer_status code to
2272 * return the name of.
2273 * \returns The error name, or the string **UNKNOWN** if the value of
2274 * error_code is not a known error / status code.
2276 DEFAULT_VISIBILITY const char * LIBUSB_CALL libusb_error_name(int error_code)
2278 switch (error_code) {
2279 case LIBUSB_ERROR_IO:
2280 return "LIBUSB_ERROR_IO";
2281 case LIBUSB_ERROR_INVALID_PARAM:
2282 return "LIBUSB_ERROR_INVALID_PARAM";
2283 case LIBUSB_ERROR_ACCESS:
2284 return "LIBUSB_ERROR_ACCESS";
2285 case LIBUSB_ERROR_NO_DEVICE:
2286 return "LIBUSB_ERROR_NO_DEVICE";
2287 case LIBUSB_ERROR_NOT_FOUND:
2288 return "LIBUSB_ERROR_NOT_FOUND";
2289 case LIBUSB_ERROR_BUSY:
2290 return "LIBUSB_ERROR_BUSY";
2291 case LIBUSB_ERROR_TIMEOUT:
2292 return "LIBUSB_ERROR_TIMEOUT";
2293 case LIBUSB_ERROR_OVERFLOW:
2294 return "LIBUSB_ERROR_OVERFLOW";
2295 case LIBUSB_ERROR_PIPE:
2296 return "LIBUSB_ERROR_PIPE";
2297 case LIBUSB_ERROR_INTERRUPTED:
2298 return "LIBUSB_ERROR_INTERRUPTED";
2299 case LIBUSB_ERROR_NO_MEM:
2300 return "LIBUSB_ERROR_NO_MEM";
2301 case LIBUSB_ERROR_NOT_SUPPORTED:
2302 return "LIBUSB_ERROR_NOT_SUPPORTED";
2303 case LIBUSB_ERROR_OTHER:
2304 return "LIBUSB_ERROR_OTHER";
2306 case LIBUSB_TRANSFER_ERROR:
2307 return "LIBUSB_TRANSFER_ERROR";
2308 case LIBUSB_TRANSFER_TIMED_OUT:
2309 return "LIBUSB_TRANSFER_TIMED_OUT";
2310 case LIBUSB_TRANSFER_CANCELLED:
2311 return "LIBUSB_TRANSFER_CANCELLED";
2312 case LIBUSB_TRANSFER_STALL:
2313 return "LIBUSB_TRANSFER_STALL";
2314 case LIBUSB_TRANSFER_NO_DEVICE:
2315 return "LIBUSB_TRANSFER_NO_DEVICE";
2316 case LIBUSB_TRANSFER_OVERFLOW:
2317 return "LIBUSB_TRANSFER_OVERFLOW";
2320 return "LIBUSB_SUCCESS / LIBUSB_TRANSFER_COMPLETED";
2322 return "**UNKNOWN**";
2327 * Returns a pointer to const struct libusb_version with the version
2328 * (major, minor, micro, nano and rc) of the running library.
2331 const struct libusb_version * LIBUSB_CALL libusb_get_version(void)
2333 return &libusb_version_internal;