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>
47 struct libusb_context *usbi_default_context = NULL;
48 static const struct libusb_version libusb_version_internal =
49 { LIBUSB_MAJOR, LIBUSB_MINOR, LIBUSB_MICRO, LIBUSB_NANO,
50 LIBUSB_RC, "http://libusb.info" };
51 static int default_context_refcnt = 0;
52 static usbi_mutex_static_t default_context_lock = USBI_MUTEX_INITIALIZER;
53 static struct timespec timestamp_origin = { 0, 0 };
55 usbi_mutex_static_t active_contexts_lock = USBI_MUTEX_INITIALIZER;
56 struct list_head active_contexts_list;
59 * \mainpage libusb-1.0 API Reference
61 * \section intro Introduction
63 * libusb is an open source library that allows you to communicate with USB
64 * devices from userspace. For more info, see the
65 * <a href="http://libusb.info">libusb homepage</a>.
67 * This documentation is aimed at application developers wishing to
68 * communicate with USB peripherals from their own software. After reviewing
69 * this documentation, feedback and questions can be sent to the
70 * <a href="http://mailing-list.libusb.info">libusb-devel mailing list</a>.
72 * This documentation assumes knowledge of how to operate USB devices from
73 * a software standpoint (descriptors, configurations, interfaces, endpoints,
74 * control/bulk/interrupt/isochronous transfers, etc). Full information
75 * can be found in the <a href="http://www.usb.org/developers/docs/">USB 3.0
76 * Specification</a> which is available for free download. You can probably
77 * find less verbose introductions by searching the web.
79 * \section API Application Programming Interface (API)
81 * See the \ref libusb_api page for a complete list of the libusb functions.
83 * \section features Library features
85 * - All transfer types supported (control/bulk/interrupt/isochronous)
86 * - 2 transfer interfaces:
87 * -# Synchronous (simple)
88 * -# Asynchronous (more complicated, but more powerful)
89 * - Thread safe (although the asynchronous interface means that you
90 * usually won't need to thread)
91 * - Lightweight with lean API
92 * - Compatible with libusb-0.1 through the libusb-compat-0.1 translation layer
93 * - Hotplug support (on some platforms). See \ref libusb_hotplug.
95 * \section gettingstarted Getting Started
97 * To begin reading the API documentation, start with the Modules page which
98 * links to the different categories of libusb's functionality.
100 * One decision you will have to make is whether to use the synchronous
101 * or the asynchronous data transfer interface. The \ref libusb_io documentation
102 * provides some insight into this topic.
104 * Some example programs can be found in the libusb source distribution under
105 * the "examples" subdirectory. The libusb homepage includes a list of
106 * real-life project examples which use libusb.
108 * \section errorhandling Error handling
110 * libusb functions typically return 0 on success or a negative error code
111 * on failure. These negative error codes relate to LIBUSB_ERROR constants
112 * which are listed on the \ref libusb_misc "miscellaneous" documentation page.
114 * \section msglog Debug message logging
116 * libusb uses stderr for all logging. By default, logging is set to NONE,
117 * which means that no output will be produced. However, unless the library
118 * has been compiled with logging disabled, then any application calls to
119 * libusb_set_option(ctx, LIBUSB_OPTION_LOG_LEVEL, level), or the setting of the
120 * environmental variable LIBUSB_DEBUG outside of the application, can result
121 * in logging being produced. Your application should therefore not close
122 * stderr, but instead direct it to the null device if its output is
125 * The libusb_set_option(ctx, LIBUSB_OPTION_LOG_LEVEL, level) function can be
126 * used to enable logging of certain messages. Under standard configuration,
127 * libusb doesn't really log much so you are advised to use this function
128 * to enable all error/warning/ informational messages. It will help debug
129 * problems with your software.
131 * The logged messages are unstructured. There is no one-to-one correspondence
132 * between messages being logged and success or failure return codes from
133 * libusb functions. There is no format to the messages, so you should not
134 * try to capture or parse them. They are not and will not be localized.
135 * These messages are not intended to being passed to your application user;
136 * instead, you should interpret the error codes returned from libusb functions
137 * and provide appropriate notification to the user. The messages are simply
138 * there to aid you as a programmer, and if you're confused because you're
139 * getting a strange error code from a libusb function, enabling message
140 * logging may give you a suitable explanation.
142 * The LIBUSB_DEBUG environment variable can be used to enable message logging
143 * at run-time. This environment variable should be set to a log level number,
144 * which is interpreted the same as the
145 * libusb_set_option(ctx, LIBUSB_OPTION_LOG_LEVEL, level) parameter. When this
146 * environment variable is set, the message logging verbosity level is fixed
147 * and libusb_set_option(ctx, LIBUSB_OPTION_LOG_LEVEL, level) effectively does
150 * libusb can be compiled without any logging functions, useful for embedded
151 * systems. In this case, libusb_set_option(ctx, LIBUSB_OPTION_LOG_LEVEL, level)
152 * and the LIBUSB_DEBUG environment variable have no effects.
154 * libusb can also be compiled with verbose debugging messages always. When
155 * the library is compiled in this way, all messages of all verbosities are
156 * always logged. libusb_set_option(ctx, LIBUSB_OPTION_LOG_LEVEL, level) and
157 * the LIBUSB_DEBUG environment variable have no effects.
159 * \section remarks Other remarks
161 * libusb does have imperfections. The \ref libusb_caveats "caveats" page attempts
166 * \page libusb_caveats Caveats
168 * \section fork Fork considerations
170 * libusb is <em>not</em> designed to work across fork() calls. Depending on
171 * the platform, there may be resources in the parent process that are not
172 * available to the child (e.g. the hotplug monitor thread on Linux). In
173 * addition, since the parent and child will share libusb's internal file
174 * descriptors, using libusb in any way from the child could cause the parent
175 * process's \ref libusb_context to get into an inconsistent state.
177 * On Linux, libusb's file descriptors will be marked as CLOEXEC, which means
178 * that it is safe to fork() and exec() without worrying about the child
179 * process needing to clean up state or having access to these file descriptors.
180 * Other platforms may not be so forgiving, so consider yourself warned!
182 * \section devresets Device resets
184 * The libusb_reset_device() function allows you to reset a device. If your
185 * program has to call such a function, it should obviously be aware that
186 * the reset will cause device state to change (e.g. register values may be
189 * The problem is that any other program could reset the device your program
190 * is working with, at any time. libusb does not offer a mechanism to inform
191 * you when this has happened, so if someone else resets your device it will
192 * not be clear to your own program why the device state has changed.
194 * Ultimately, this is a limitation of writing drivers in userspace.
195 * Separation from the USB stack in the underlying kernel makes it difficult
196 * for the operating system to deliver such notifications to your program.
197 * The Linux kernel USB stack allows such reset notifications to be delivered
198 * to in-kernel USB drivers, but it is not clear how such notifications could
199 * be delivered to second-class drivers that live in userspace.
201 * \section blockonly Blocking-only functionality
203 * The functionality listed below is only available through synchronous,
204 * blocking functions. There are no asynchronous/non-blocking alternatives,
205 * and no clear ways of implementing these.
207 * - Configuration activation (libusb_set_configuration())
208 * - Interface/alternate setting activation (libusb_set_interface_alt_setting())
209 * - Releasing of interfaces (libusb_release_interface())
210 * - Clearing of halt/stall condition (libusb_clear_halt())
211 * - Device resets (libusb_reset_device())
213 * \section configsel Configuration selection and handling
215 * When libusb presents a device handle to an application, there is a chance
216 * that the corresponding device may be in unconfigured state. For devices
217 * with multiple configurations, there is also a chance that the configuration
218 * currently selected is not the one that the application wants to use.
220 * The obvious solution is to add a call to libusb_set_configuration() early
221 * on during your device initialization routines, but there are caveats to
223 * -# If the device is already in the desired configuration, calling
224 * libusb_set_configuration() using the same configuration value will cause
225 * a lightweight device reset. This may not be desirable behaviour.
226 * -# In the case where the desired configuration is already active, libusb
227 * may not even be able to perform a lightweight device reset. For example,
228 * take my USB keyboard with fingerprint reader: I'm interested in driving
229 * the fingerprint reader interface through libusb, but the kernel's
230 * USB-HID driver will almost always have claimed the keyboard interface.
231 * Because the kernel has claimed an interface, it is not even possible to
232 * perform the lightweight device reset, so libusb_set_configuration() will
233 * fail. (Luckily the device in question only has a single configuration.)
234 * -# libusb will be unable to set a configuration if other programs or
235 * drivers have claimed interfaces. In particular, this means that kernel
236 * drivers must be detached from all the interfaces before
237 * libusb_set_configuration() may succeed.
239 * One solution to some of the above problems is to consider the currently
240 * active configuration. If the configuration we want is already active, then
241 * we don't have to select any configuration:
244 libusb_get_configuration(dev, &cfg);
246 libusb_set_configuration(dev, desired);
249 * This is probably suitable for most scenarios, but is inherently racy:
250 * another application or driver may change the selected configuration
251 * <em>after</em> the libusb_get_configuration() call.
253 * Even in cases where libusb_set_configuration() succeeds, consider that other
254 * applications or drivers may change configuration after your application
255 * calls libusb_set_configuration().
257 * One possible way to lock your device into a specific configuration is as
259 * -# Set the desired configuration (or use the logic above to realise that
260 * it is already in the desired configuration)
261 * -# Claim the interface that you wish to use
262 * -# Check that the currently active configuration is the one that you want
265 * The above method works because once an interface is claimed, no application
266 * or driver is able to select another configuration.
268 * \section earlycomp Early transfer completion
270 * NOTE: This section is currently Linux-centric. I am not sure if any of these
271 * considerations apply to Darwin or other platforms.
273 * When a transfer completes early (i.e. when less data is received/sent in
274 * any one packet than the transfer buffer allows for) then libusb is designed
275 * to terminate the transfer immediately, not transferring or receiving any
276 * more data unless other transfers have been queued by the user.
278 * On legacy platforms, libusb is unable to do this in all situations. After
279 * the incomplete packet occurs, "surplus" data may be transferred. For recent
280 * versions of libusb, this information is kept (the data length of the
281 * transfer is updated) and, for device-to-host transfers, any surplus data was
282 * added to the buffer. Still, this is not a nice solution because it loses the
283 * information about the end of the short packet, and the user probably wanted
284 * that surplus data to arrive in the next logical transfer.
286 * \section zlp Zero length packets
288 * - libusb is able to send a packet of zero length to an endpoint simply by
289 * submitting a transfer of zero length.
290 * - The \ref libusb_transfer_flags::LIBUSB_TRANSFER_ADD_ZERO_PACKET
291 * "LIBUSB_TRANSFER_ADD_ZERO_PACKET" flag is currently only supported on Linux.
295 * \page libusb_contexts Contexts
297 * It is possible that libusb may be used simultaneously from two independent
298 * libraries linked into the same executable. For example, if your application
299 * has a plugin-like system which allows the user to dynamically load a range
300 * of modules into your program, it is feasible that two independently
301 * developed modules may both use libusb.
303 * libusb is written to allow for these multiple user scenarios. The two
304 * "instances" of libusb will not interfere: libusb_set_option() calls
305 * from one user will not affect the same settings for other users, other
306 * users can continue using libusb after one of them calls libusb_exit(), etc.
308 * This is made possible through libusb's <em>context</em> concept. When you
309 * call libusb_init(), you are (optionally) given a context. You can then pass
310 * this context pointer back into future libusb functions.
312 * In order to keep things simple for more simplistic applications, it is
313 * legal to pass NULL to all functions requiring a context pointer (as long as
314 * you're sure no other code will attempt to use libusb from the same process).
315 * When you pass NULL, the default context will be used. The default context
316 * is created the first time a process calls libusb_init() when no other
317 * context is alive. Contexts are destroyed during libusb_exit().
319 * The default context is reference-counted and can be shared. That means that
320 * if libusb_init(NULL) is called twice within the same process, the two
321 * users end up sharing the same context. The deinitialization and freeing of
322 * the default context will only happen when the last user calls libusb_exit().
323 * In other words, the default context is created and initialized when its
324 * reference count goes from 0 to 1, and is deinitialized and destroyed when
325 * its reference count goes from 1 to 0.
327 * You may be wondering why only a subset of libusb functions require a
328 * context pointer in their function definition. Internally, libusb stores
329 * context pointers in other objects (e.g. libusb_device instances) and hence
330 * can infer the context from those objects.
334 * \page libusb_api Application Programming Interface
336 * This is the complete list of libusb functions, structures and
337 * enumerations in alphabetical order.
340 * - libusb_alloc_streams()
341 * - libusb_alloc_transfer()
342 * - libusb_attach_kernel_driver()
343 * - libusb_bulk_transfer()
344 * - libusb_cancel_transfer()
345 * - libusb_claim_interface()
346 * - libusb_clear_halt()
348 * - libusb_control_transfer()
349 * - libusb_control_transfer_get_data()
350 * - libusb_control_transfer_get_setup()
351 * - libusb_cpu_to_le16()
352 * - libusb_detach_kernel_driver()
353 * - libusb_dev_mem_alloc()
354 * - libusb_dev_mem_free()
355 * - libusb_error_name()
356 * - libusb_event_handler_active()
357 * - libusb_event_handling_ok()
359 * - libusb_fill_bulk_stream_transfer()
360 * - libusb_fill_bulk_transfer()
361 * - libusb_fill_control_setup()
362 * - libusb_fill_control_transfer()
363 * - libusb_fill_interrupt_transfer()
364 * - libusb_fill_iso_transfer()
365 * - libusb_free_bos_descriptor()
366 * - libusb_free_config_descriptor()
367 * - libusb_free_container_id_descriptor()
368 * - libusb_free_device_list()
369 * - libusb_free_pollfds()
370 * - libusb_free_ss_endpoint_companion_descriptor()
371 * - libusb_free_ss_usb_device_capability_descriptor()
372 * - libusb_free_streams()
373 * - libusb_free_transfer()
374 * - libusb_free_usb_2_0_extension_descriptor()
375 * - libusb_get_active_config_descriptor()
376 * - libusb_get_bos_descriptor()
377 * - libusb_get_bus_number()
378 * - libusb_get_config_descriptor()
379 * - libusb_get_config_descriptor_by_value()
380 * - libusb_get_configuration()
381 * - libusb_get_container_id_descriptor()
382 * - libusb_get_descriptor()
383 * - libusb_get_device()
384 * - libusb_get_device_address()
385 * - libusb_get_device_descriptor()
386 * - libusb_get_device_list()
387 * - libusb_get_device_speed()
388 * - libusb_get_iso_packet_buffer()
389 * - libusb_get_iso_packet_buffer_simple()
390 * - libusb_get_max_iso_packet_size()
391 * - libusb_get_max_packet_size()
392 * - libusb_get_next_timeout()
393 * - libusb_get_parent()
394 * - libusb_get_pollfds()
395 * - libusb_get_port_number()
396 * - libusb_get_port_numbers()
397 * - libusb_get_port_path()
398 * - libusb_get_ss_endpoint_companion_descriptor()
399 * - libusb_get_ss_usb_device_capability_descriptor()
400 * - libusb_get_string_descriptor()
401 * - libusb_get_string_descriptor_ascii()
402 * - libusb_get_usb_2_0_extension_descriptor()
403 * - libusb_get_version()
404 * - libusb_handle_events()
405 * - libusb_handle_events_completed()
406 * - libusb_handle_events_locked()
407 * - libusb_handle_events_timeout()
408 * - libusb_handle_events_timeout_completed()
409 * - libusb_has_capability()
410 * - libusb_hotplug_deregister_callback()
411 * - libusb_hotplug_register_callback()
413 * - libusb_interrupt_event_handler()
414 * - libusb_interrupt_transfer()
415 * - libusb_kernel_driver_active()
416 * - libusb_lock_events()
417 * - libusb_lock_event_waiters()
419 * - libusb_open_device_with_vid_pid()
420 * - libusb_pollfds_handle_timeouts()
421 * - libusb_ref_device()
422 * - libusb_release_interface()
423 * - libusb_reset_device()
424 * - libusb_set_auto_detach_kernel_driver()
425 * - libusb_set_configuration()
426 * - libusb_set_debug()
427 * - libusb_set_interface_alt_setting()
428 * - libusb_set_iso_packet_lengths()
429 * - libusb_set_option()
430 * - libusb_setlocale()
431 * - libusb_set_pollfd_notifiers()
432 * - libusb_strerror()
433 * - libusb_submit_transfer()
434 * - libusb_transfer_get_stream_id()
435 * - libusb_transfer_set_stream_id()
436 * - libusb_try_lock_events()
437 * - libusb_unlock_events()
438 * - libusb_unlock_event_waiters()
439 * - libusb_unref_device()
440 * - libusb_wait_for_event()
442 * \section Structures
443 * - libusb_bos_descriptor
444 * - libusb_bos_dev_capability_descriptor
445 * - libusb_config_descriptor
446 * - libusb_container_id_descriptor
447 * - \ref libusb_context
448 * - libusb_control_setup
449 * - \ref libusb_device
450 * - libusb_device_descriptor
451 * - \ref libusb_device_handle
452 * - libusb_endpoint_descriptor
454 * - libusb_interface_descriptor
455 * - libusb_iso_packet_descriptor
457 * - libusb_ss_endpoint_companion_descriptor
458 * - libusb_ss_usb_device_capability_descriptor
460 * - libusb_usb_2_0_extension_descriptor
464 * - \ref libusb_bos_type
465 * - \ref libusb_capability
466 * - \ref libusb_class_code
467 * - \ref libusb_descriptor_type
468 * - \ref libusb_endpoint_direction
469 * - \ref libusb_error
470 * - \ref libusb_iso_sync_type
471 * - \ref libusb_iso_usage_type
472 * - \ref libusb_log_level
473 * - \ref libusb_option
474 * - \ref libusb_request_recipient
475 * - \ref libusb_request_type
476 * - \ref libusb_speed
477 * - \ref libusb_ss_usb_device_capability_attributes
478 * - \ref libusb_standard_request
479 * - \ref libusb_supported_speed
480 * - \ref libusb_transfer_flags
481 * - \ref libusb_transfer_status
482 * - \ref libusb_transfer_type
483 * - \ref libusb_usb_2_0_extension_attributes
487 * @defgroup libusb_lib Library initialization/deinitialization
488 * This page details how to initialize and deinitialize libusb. Initialization
489 * must be performed before using any libusb functionality, and similarly you
490 * must not call any libusb functions after deinitialization.
494 * @defgroup libusb_dev Device handling and enumeration
495 * The functionality documented below is designed to help with the following
497 * - Enumerating the USB devices currently attached to the system
498 * - Choosing a device to operate from your software
499 * - Opening and closing the chosen device
501 * \section nutshell In a nutshell...
503 * The description below really makes things sound more complicated than they
504 * actually are. The following sequence of function calls will be suitable
505 * for almost all scenarios and does not require you to have such a deep
506 * understanding of the resource management issues:
509 libusb_device **list;
510 libusb_device *found = NULL;
511 ssize_t cnt = libusb_get_device_list(NULL, &list);
517 for (i = 0; i < cnt; i++) {
518 libusb_device *device = list[i];
519 if (is_interesting(device)) {
526 libusb_device_handle *handle;
528 err = libusb_open(found, &handle);
534 libusb_free_device_list(list, 1);
537 * The two important points:
538 * - You asked libusb_free_device_list() to unreference the devices (2nd
540 * - You opened the device before freeing the list and unreferencing the
543 * If you ended up with a handle, you can now proceed to perform I/O on the
546 * \section devshandles Devices and device handles
547 * libusb has a concept of a USB device, represented by the
548 * \ref libusb_device opaque type. A device represents a USB device that
549 * is currently or was previously connected to the system. Using a reference
550 * to a device, you can determine certain information about the device (e.g.
551 * you can read the descriptor data).
553 * The libusb_get_device_list() function can be used to obtain a list of
554 * devices currently connected to the system. This is known as device
557 * Just because you have a reference to a device does not mean it is
558 * necessarily usable. The device may have been unplugged, you may not have
559 * permission to operate such device, or another program or driver may be
562 * When you've found a device that you'd like to operate, you must ask
563 * libusb to open the device using the libusb_open() function. Assuming
564 * success, libusb then returns you a <em>device handle</em>
565 * (a \ref libusb_device_handle pointer). All "real" I/O operations then
566 * operate on the handle rather than the original device pointer.
568 * \section devref Device discovery and reference counting
570 * Device discovery (i.e. calling libusb_get_device_list()) returns a
571 * freshly-allocated list of devices. The list itself must be freed when
572 * you are done with it. libusb also needs to know when it is OK to free
573 * the contents of the list - the devices themselves.
575 * To handle these issues, libusb provides you with two separate items:
576 * - A function to free the list itself
577 * - A reference counting system for the devices inside
579 * New devices presented by the libusb_get_device_list() function all have a
580 * reference count of 1. You can increase and decrease reference count using
581 * libusb_ref_device() and libusb_unref_device(). A device is destroyed when
582 * its reference count reaches 0.
584 * With the above information in mind, the process of opening a device can
585 * be viewed as follows:
586 * -# Discover devices using libusb_get_device_list().
587 * -# Choose the device that you want to operate, and call libusb_open().
588 * -# Unref all devices in the discovered device list.
589 * -# Free the discovered device list.
591 * The order is important - you must not unreference the device before
592 * attempting to open it, because unreferencing it may destroy the device.
594 * For convenience, the libusb_free_device_list() function includes a
595 * parameter to optionally unreference all the devices in the list before
596 * freeing the list itself. This combines steps 3 and 4 above.
598 * As an implementation detail, libusb_open() actually adds a reference to
599 * the device in question. This is because the device remains available
600 * through the handle via libusb_get_device(). The reference is deleted during
604 /** @defgroup libusb_misc Miscellaneous */
606 /* we traverse usbfs without knowing how many devices we are going to find.
607 * so we create this discovered_devs model which is similar to a linked-list
608 * which grows when required. it can be freed once discovery has completed,
609 * eliminating the need for a list node in the libusb_device structure
611 #define DISCOVERED_DEVICES_SIZE_STEP 8
613 static struct discovered_devs *discovered_devs_alloc(void)
615 struct discovered_devs *ret =
616 malloc(sizeof(*ret) + (sizeof(void *) * DISCOVERED_DEVICES_SIZE_STEP));
620 ret->capacity = DISCOVERED_DEVICES_SIZE_STEP;
625 static void discovered_devs_free(struct discovered_devs *discdevs)
629 for (i = 0; i < discdevs->len; i++)
630 libusb_unref_device(discdevs->devices[i]);
635 /* append a device to the discovered devices collection. may realloc itself,
636 * returning new discdevs. returns NULL on realloc failure. */
637 struct discovered_devs *discovered_devs_append(
638 struct discovered_devs *discdevs, struct libusb_device *dev)
640 size_t len = discdevs->len;
642 struct discovered_devs *new_discdevs;
644 /* if there is space, just append the device */
645 if (len < discdevs->capacity) {
646 discdevs->devices[len] = libusb_ref_device(dev);
651 /* exceeded capacity, need to grow */
652 usbi_dbg("need to increase capacity");
653 capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
654 /* can't use usbi_reallocf here because in failure cases it would
655 * free the existing discdevs without unreferencing its devices. */
656 new_discdevs = realloc(discdevs,
657 sizeof(*discdevs) + (sizeof(void *) * capacity));
659 discovered_devs_free(discdevs);
663 discdevs = new_discdevs;
664 discdevs->capacity = capacity;
665 discdevs->devices[len] = libusb_ref_device(dev);
671 /* Allocate a new device with a specific session ID. The returned device has
672 * a reference count of 1. */
673 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
674 unsigned long session_id)
676 size_t priv_size = usbi_backend.device_priv_size;
677 struct libusb_device *dev = calloc(1, sizeof(*dev) + priv_size);
683 r = usbi_mutex_init(&dev->lock);
691 dev->session_data = session_id;
692 dev->speed = LIBUSB_SPEED_UNKNOWN;
694 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
695 usbi_connect_device (dev);
701 void usbi_connect_device(struct libusb_device *dev)
703 struct libusb_context *ctx = DEVICE_CTX(dev);
707 usbi_mutex_lock(&dev->ctx->usb_devs_lock);
708 list_add(&dev->list, &dev->ctx->usb_devs);
709 usbi_mutex_unlock(&dev->ctx->usb_devs_lock);
711 /* Signal that an event has occurred for this device if we support hotplug AND
712 * the hotplug message list is ready. This prevents an event from getting raised
713 * during initial enumeration. */
714 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG) && dev->ctx->hotplug_msgs.next) {
715 usbi_hotplug_notification(ctx, dev, LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED);
719 void usbi_disconnect_device(struct libusb_device *dev)
721 struct libusb_context *ctx = DEVICE_CTX(dev);
723 usbi_mutex_lock(&dev->lock);
725 usbi_mutex_unlock(&dev->lock);
727 usbi_mutex_lock(&ctx->usb_devs_lock);
728 list_del(&dev->list);
729 usbi_mutex_unlock(&ctx->usb_devs_lock);
731 /* Signal that an event has occurred for this device if we support hotplug AND
732 * the hotplug message list is ready. This prevents an event from getting raised
733 * during initial enumeration. libusb_handle_events will take care of dereferencing
735 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG) && dev->ctx->hotplug_msgs.next) {
736 usbi_hotplug_notification(ctx, dev, LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT);
740 /* Perform some final sanity checks on a newly discovered device. If this
741 * function fails (negative return code), the device should not be added
742 * to the discovered device list. */
743 int usbi_sanitize_device(struct libusb_device *dev)
746 uint8_t num_configurations;
748 r = usbi_device_cache_descriptor(dev);
752 num_configurations = dev->device_descriptor.bNumConfigurations;
753 if (num_configurations > USB_MAXCONFIG) {
754 usbi_err(DEVICE_CTX(dev), "too many configurations");
755 return LIBUSB_ERROR_IO;
756 } else if (0 == num_configurations)
757 usbi_dbg("zero configurations, maybe an unauthorized device");
759 dev->num_configurations = num_configurations;
763 /* Examine libusb's internal list of known devices, looking for one with
764 * a specific session ID. Returns the matching device if it was found, and
766 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
767 unsigned long session_id)
769 struct libusb_device *dev;
770 struct libusb_device *ret = NULL;
772 usbi_mutex_lock(&ctx->usb_devs_lock);
773 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device)
774 if (dev->session_data == session_id) {
775 ret = libusb_ref_device(dev);
778 usbi_mutex_unlock(&ctx->usb_devs_lock);
783 /** @ingroup libusb_dev
784 * Returns a list of USB devices currently attached to the system. This is
785 * your entry point into finding a USB device to operate.
787 * You are expected to unreference all the devices when you are done with
788 * them, and then free the list with libusb_free_device_list(). Note that
789 * libusb_free_device_list() can unref all the devices for you. Be careful
790 * not to unreference a device you are about to open until after you have
793 * This return value of this function indicates the number of devices in
794 * the resultant list. The list is actually one element larger, as it is
797 * \param ctx the context to operate on, or NULL for the default context
798 * \param list output location for a list of devices. Must be later freed with
799 * libusb_free_device_list().
800 * \returns the number of devices in the outputted list, or any
801 * \ref libusb_error according to errors encountered by the backend.
803 ssize_t API_EXPORTED libusb_get_device_list(libusb_context *ctx,
804 libusb_device ***list)
806 struct discovered_devs *discdevs = discovered_devs_alloc();
807 struct libusb_device **ret;
810 USBI_GET_CONTEXT(ctx);
814 return LIBUSB_ERROR_NO_MEM;
816 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
817 /* backend provides hotplug support */
818 struct libusb_device *dev;
820 if (usbi_backend.hotplug_poll)
821 usbi_backend.hotplug_poll();
823 usbi_mutex_lock(&ctx->usb_devs_lock);
824 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device) {
825 discdevs = discovered_devs_append(discdevs, dev);
828 r = LIBUSB_ERROR_NO_MEM;
832 usbi_mutex_unlock(&ctx->usb_devs_lock);
834 /* backend does not provide hotplug support */
835 r = usbi_backend.get_device_list(ctx, &discdevs);
843 /* convert discovered_devs into a list */
845 ret = calloc(len + 1, sizeof(struct libusb_device *));
847 len = LIBUSB_ERROR_NO_MEM;
852 for (i = 0; i < len; i++) {
853 struct libusb_device *dev = discdevs->devices[i];
854 ret[i] = libusb_ref_device(dev);
860 discovered_devs_free(discdevs);
864 /** \ingroup libusb_dev
865 * Frees a list of devices previously discovered using
866 * libusb_get_device_list(). If the unref_devices parameter is set, the
867 * reference count of each device in the list is decremented by 1.
868 * \param list the list to free
869 * \param unref_devices whether to unref the devices in the list
871 void API_EXPORTED libusb_free_device_list(libusb_device **list,
879 struct libusb_device *dev;
881 while ((dev = list[i++]) != NULL)
882 libusb_unref_device(dev);
887 /** \ingroup libusb_dev
888 * Get the number of the bus that a device is connected to.
889 * \param dev a device
890 * \returns the bus number
892 uint8_t API_EXPORTED libusb_get_bus_number(libusb_device *dev)
894 return dev->bus_number;
897 /** \ingroup libusb_dev
898 * Get the number of the port that a device is connected to.
899 * Unless the OS does something funky, or you are hot-plugging USB extension cards,
900 * the port number returned by this call is usually guaranteed to be uniquely tied
901 * to a physical port, meaning that different devices plugged on the same physical
902 * port should return the same port number.
904 * But outside of this, there is no guarantee that the port number returned by this
905 * call will remain the same, or even match the order in which ports have been
906 * numbered by the HUB/HCD manufacturer.
908 * \param dev a device
909 * \returns the port number (0 if not available)
911 uint8_t API_EXPORTED libusb_get_port_number(libusb_device *dev)
913 return dev->port_number;
916 /** \ingroup libusb_dev
917 * Get the list of all port numbers from root for the specified device
919 * Since version 1.0.16, \ref LIBUSB_API_VERSION >= 0x01000102
920 * \param dev a device
921 * \param port_numbers the array that should contain the port numbers
922 * \param port_numbers_len the maximum length of the array. As per the USB 3.0
923 * specs, the current maximum limit for the depth is 7.
924 * \returns the number of elements filled
925 * \returns LIBUSB_ERROR_OVERFLOW if the array is too small
927 int API_EXPORTED libusb_get_port_numbers(libusb_device *dev,
928 uint8_t* port_numbers, int port_numbers_len)
930 int i = port_numbers_len;
931 struct libusb_context *ctx = DEVICE_CTX(dev);
933 if (port_numbers_len <= 0)
934 return LIBUSB_ERROR_INVALID_PARAM;
936 // HCDs can be listed as devices with port #0
937 while((dev) && (dev->port_number != 0)) {
939 usbi_warn(ctx, "port numbers array is too small");
940 return LIBUSB_ERROR_OVERFLOW;
942 port_numbers[i] = dev->port_number;
943 dev = dev->parent_dev;
945 if (i < port_numbers_len)
946 memmove(port_numbers, &port_numbers[i], port_numbers_len - i);
947 return port_numbers_len - i;
950 /** \ingroup libusb_dev
951 * Deprecated please use libusb_get_port_numbers instead.
953 int API_EXPORTED libusb_get_port_path(libusb_context *ctx, libusb_device *dev,
954 uint8_t* port_numbers, uint8_t port_numbers_len)
958 return libusb_get_port_numbers(dev, port_numbers, port_numbers_len);
961 /** \ingroup libusb_dev
962 * Get the the parent from the specified device.
963 * \param dev a device
964 * \returns the device parent or NULL if not available
965 * You should issue a \ref libusb_get_device_list() before calling this
966 * function and make sure that you only access the parent before issuing
967 * \ref libusb_free_device_list(). The reason is that libusb currently does
968 * not maintain a permanent list of device instances, and therefore can
969 * only guarantee that parents are fully instantiated within a
970 * libusb_get_device_list() - libusb_free_device_list() block.
973 libusb_device * LIBUSB_CALL libusb_get_parent(libusb_device *dev)
975 return dev->parent_dev;
978 /** \ingroup libusb_dev
979 * Get the address of the device on the bus it is connected to.
980 * \param dev a device
981 * \returns the device address
983 uint8_t API_EXPORTED libusb_get_device_address(libusb_device *dev)
985 return dev->device_address;
988 /** \ingroup libusb_dev
989 * Get the negotiated connection speed for a device.
990 * \param dev a device
991 * \returns a \ref libusb_speed code, where LIBUSB_SPEED_UNKNOWN means that
992 * the OS doesn't know or doesn't support returning the negotiated speed.
994 int API_EXPORTED libusb_get_device_speed(libusb_device *dev)
999 static const struct libusb_endpoint_descriptor *find_endpoint(
1000 struct libusb_config_descriptor *config, unsigned char endpoint)
1003 for (iface_idx = 0; iface_idx < config->bNumInterfaces; iface_idx++) {
1004 const struct libusb_interface *iface = &config->interface[iface_idx];
1007 for (altsetting_idx = 0; altsetting_idx < iface->num_altsetting;
1009 const struct libusb_interface_descriptor *altsetting
1010 = &iface->altsetting[altsetting_idx];
1013 for (ep_idx = 0; ep_idx < altsetting->bNumEndpoints; ep_idx++) {
1014 const struct libusb_endpoint_descriptor *ep =
1015 &altsetting->endpoint[ep_idx];
1016 if (ep->bEndpointAddress == endpoint)
1024 /** \ingroup libusb_dev
1025 * Convenience function to retrieve the wMaxPacketSize value for a particular
1026 * endpoint in the active device configuration.
1028 * This function was originally intended to be of assistance when setting up
1029 * isochronous transfers, but a design mistake resulted in this function
1030 * instead. It simply returns the wMaxPacketSize value without considering
1031 * its contents. If you're dealing with isochronous transfers, you probably
1032 * want libusb_get_max_iso_packet_size() instead.
1034 * \param dev a device
1035 * \param endpoint address of the endpoint in question
1036 * \returns the wMaxPacketSize value
1037 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
1038 * \returns LIBUSB_ERROR_OTHER on other failure
1040 int API_EXPORTED libusb_get_max_packet_size(libusb_device *dev,
1041 unsigned char endpoint)
1043 struct libusb_config_descriptor *config;
1044 const struct libusb_endpoint_descriptor *ep;
1047 r = libusb_get_active_config_descriptor(dev, &config);
1049 usbi_err(DEVICE_CTX(dev),
1050 "could not retrieve active config descriptor");
1051 return LIBUSB_ERROR_OTHER;
1054 ep = find_endpoint(config, endpoint);
1056 r = LIBUSB_ERROR_NOT_FOUND;
1060 r = ep->wMaxPacketSize;
1063 libusb_free_config_descriptor(config);
1067 /** \ingroup libusb_dev
1068 * Calculate the maximum packet size which a specific endpoint is capable is
1069 * sending or receiving in the duration of 1 microframe
1071 * Only the active configuration is examined. The calculation is based on the
1072 * wMaxPacketSize field in the endpoint descriptor as described in section
1073 * 9.6.6 in the USB 2.0 specifications.
1075 * If acting on an isochronous or interrupt endpoint, this function will
1076 * multiply the value found in bits 0:10 by the number of transactions per
1077 * microframe (determined by bits 11:12). Otherwise, this function just
1078 * returns the numeric value found in bits 0:10.
1080 * This function is useful for setting up isochronous transfers, for example
1081 * you might pass the return value from this function to
1082 * libusb_set_iso_packet_lengths() in order to set the length field of every
1083 * isochronous packet in a transfer.
1087 * \param dev a device
1088 * \param endpoint address of the endpoint in question
1089 * \returns the maximum packet size which can be sent/received on this endpoint
1090 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
1091 * \returns LIBUSB_ERROR_OTHER on other failure
1093 int API_EXPORTED libusb_get_max_iso_packet_size(libusb_device *dev,
1094 unsigned char endpoint)
1096 struct libusb_config_descriptor *config;
1097 const struct libusb_endpoint_descriptor *ep;
1098 enum libusb_transfer_type ep_type;
1102 r = libusb_get_active_config_descriptor(dev, &config);
1104 usbi_err(DEVICE_CTX(dev),
1105 "could not retrieve active config descriptor");
1106 return LIBUSB_ERROR_OTHER;
1109 ep = find_endpoint(config, endpoint);
1111 r = LIBUSB_ERROR_NOT_FOUND;
1115 val = ep->wMaxPacketSize;
1116 ep_type = (enum libusb_transfer_type) (ep->bmAttributes & 0x3);
1119 if (ep_type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
1120 || ep_type == LIBUSB_TRANSFER_TYPE_INTERRUPT)
1121 r *= (1 + ((val >> 11) & 3));
1124 libusb_free_config_descriptor(config);
1128 /** \ingroup libusb_dev
1129 * Increment the reference count of a device.
1130 * \param dev the device to reference
1131 * \returns the same device
1134 libusb_device * LIBUSB_CALL libusb_ref_device(libusb_device *dev)
1136 usbi_mutex_lock(&dev->lock);
1138 usbi_mutex_unlock(&dev->lock);
1142 /** \ingroup libusb_dev
1143 * Decrement the reference count of a device. If the decrement operation
1144 * causes the reference count to reach zero, the device shall be destroyed.
1145 * \param dev the device to unreference
1147 void API_EXPORTED libusb_unref_device(libusb_device *dev)
1154 usbi_mutex_lock(&dev->lock);
1155 refcnt = --dev->refcnt;
1156 usbi_mutex_unlock(&dev->lock);
1159 usbi_dbg("destroy device %d.%d", dev->bus_number, dev->device_address);
1161 libusb_unref_device(dev->parent_dev);
1163 if (usbi_backend.destroy_device)
1164 usbi_backend.destroy_device(dev);
1166 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
1167 /* backend does not support hotplug */
1168 usbi_disconnect_device(dev);
1171 usbi_mutex_destroy(&dev->lock);
1177 * Signal the event pipe so that the event handling thread will be
1178 * interrupted to process an internal event.
1180 int usbi_signal_event(struct libusb_context *ctx)
1182 unsigned char dummy = 1;
1185 /* write some data on event pipe to interrupt event handlers */
1186 r = usbi_write(ctx->event_pipe[1], &dummy, sizeof(dummy));
1187 if (r != sizeof(dummy)) {
1188 usbi_warn(ctx, "internal signalling write failed");
1189 return LIBUSB_ERROR_IO;
1196 * Clear the event pipe so that the event handling will no longer be
1199 int usbi_clear_event(struct libusb_context *ctx)
1201 unsigned char dummy;
1204 /* read some data on event pipe to clear it */
1205 r = usbi_read(ctx->event_pipe[0], &dummy, sizeof(dummy));
1206 if (r != sizeof(dummy)) {
1207 usbi_warn(ctx, "internal signalling read failed");
1208 return LIBUSB_ERROR_IO;
1214 /** \ingroup libusb_dev
1215 * Open a device and obtain a device handle. A handle allows you to perform
1216 * I/O on the device in question.
1218 * Internally, this function adds a reference to the device and makes it
1219 * available to you through libusb_get_device(). This reference is removed
1220 * during libusb_close().
1222 * This is a non-blocking function; no requests are sent over the bus.
1224 * \param dev the device to open
1225 * \param dev_handle output location for the returned device handle pointer. Only
1226 * populated when the return code is 0.
1227 * \returns 0 on success
1228 * \returns LIBUSB_ERROR_NO_MEM on memory allocation failure
1229 * \returns LIBUSB_ERROR_ACCESS if the user has insufficient permissions
1230 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1231 * \returns another LIBUSB_ERROR code on other failure
1233 int API_EXPORTED libusb_open(libusb_device *dev,
1234 libusb_device_handle **dev_handle)
1236 struct libusb_context *ctx = DEVICE_CTX(dev);
1237 struct libusb_device_handle *_dev_handle;
1238 size_t priv_size = usbi_backend.device_handle_priv_size;
1240 usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);
1242 if (!dev->attached) {
1243 return LIBUSB_ERROR_NO_DEVICE;
1246 _dev_handle = malloc(sizeof(*_dev_handle) + priv_size);
1248 return LIBUSB_ERROR_NO_MEM;
1250 r = usbi_mutex_init(&_dev_handle->lock);
1253 return LIBUSB_ERROR_OTHER;
1256 _dev_handle->dev = libusb_ref_device(dev);
1257 _dev_handle->auto_detach_kernel_driver = 0;
1258 _dev_handle->claimed_interfaces = 0;
1259 memset(&_dev_handle->os_priv, 0, priv_size);
1261 r = usbi_backend.open(_dev_handle);
1263 usbi_dbg("open %d.%d returns %d", dev->bus_number, dev->device_address, r);
1264 libusb_unref_device(dev);
1265 usbi_mutex_destroy(&_dev_handle->lock);
1270 usbi_mutex_lock(&ctx->open_devs_lock);
1271 list_add(&_dev_handle->list, &ctx->open_devs);
1272 usbi_mutex_unlock(&ctx->open_devs_lock);
1273 *dev_handle = _dev_handle;
1278 /** \ingroup libusb_dev
1279 * Convenience function for finding a device with a particular
1280 * <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
1281 * for those scenarios where you are using libusb to knock up a quick test
1282 * application - it allows you to avoid calling libusb_get_device_list() and
1283 * worrying about traversing/freeing the list.
1285 * This function has limitations and is hence not intended for use in real
1286 * applications: if multiple devices have the same IDs it will only
1287 * give you the first one, etc.
1289 * \param ctx the context to operate on, or NULL for the default context
1290 * \param vendor_id the idVendor value to search for
1291 * \param product_id the idProduct value to search for
1292 * \returns a device handle for the first found device, or NULL on error
1293 * or if the device could not be found. */
1295 libusb_device_handle * LIBUSB_CALL libusb_open_device_with_vid_pid(
1296 libusb_context *ctx, uint16_t vendor_id, uint16_t product_id)
1298 struct libusb_device **devs;
1299 struct libusb_device *found = NULL;
1300 struct libusb_device *dev;
1301 struct libusb_device_handle *dev_handle = NULL;
1305 if (libusb_get_device_list(ctx, &devs) < 0)
1308 while ((dev = devs[i++]) != NULL) {
1309 struct libusb_device_descriptor desc;
1310 r = libusb_get_device_descriptor(dev, &desc);
1313 if (desc.idVendor == vendor_id && desc.idProduct == product_id) {
1320 r = libusb_open(found, &dev_handle);
1326 libusb_free_device_list(devs, 1);
1330 static void do_close(struct libusb_context *ctx,
1331 struct libusb_device_handle *dev_handle)
1333 struct usbi_transfer *itransfer;
1334 struct usbi_transfer *tmp;
1336 /* remove any transfers in flight that are for this device */
1337 usbi_mutex_lock(&ctx->flying_transfers_lock);
1339 /* safe iteration because transfers may be being deleted */
1340 list_for_each_entry_safe(itransfer, tmp, &ctx->flying_transfers, list, struct usbi_transfer) {
1341 struct libusb_transfer *transfer =
1342 USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
1344 if (transfer->dev_handle != dev_handle)
1347 usbi_mutex_lock(&itransfer->lock);
1348 if (!(itransfer->state_flags & USBI_TRANSFER_DEVICE_DISAPPEARED)) {
1349 usbi_err(ctx, "Device handle closed while transfer was still being processed, but the device is still connected as far as we know");
1351 if (itransfer->state_flags & USBI_TRANSFER_CANCELLING)
1352 usbi_warn(ctx, "A cancellation for an in-flight transfer hasn't completed but closing the device handle");
1354 usbi_err(ctx, "A cancellation hasn't even been scheduled on the transfer for which the device is closing");
1356 usbi_mutex_unlock(&itransfer->lock);
1358 /* remove from the list of in-flight transfers and make sure
1359 * we don't accidentally use the device handle in the future
1360 * (or that such accesses will be easily caught and identified as a crash)
1362 list_del(&itransfer->list);
1363 transfer->dev_handle = NULL;
1365 /* it is up to the user to free up the actual transfer struct. this is
1366 * just making sure that we don't attempt to process the transfer after
1367 * the device handle is invalid
1369 usbi_dbg("Removed transfer %p from the in-flight list because device handle %p closed",
1370 transfer, dev_handle);
1372 usbi_mutex_unlock(&ctx->flying_transfers_lock);
1374 usbi_mutex_lock(&ctx->open_devs_lock);
1375 list_del(&dev_handle->list);
1376 usbi_mutex_unlock(&ctx->open_devs_lock);
1378 usbi_backend.close(dev_handle);
1379 libusb_unref_device(dev_handle->dev);
1380 usbi_mutex_destroy(&dev_handle->lock);
1384 /** \ingroup libusb_dev
1385 * Close a device handle. Should be called on all open handles before your
1386 * application exits.
1388 * Internally, this function destroys the reference that was added by
1389 * libusb_open() on the given device.
1391 * This is a non-blocking function; no requests are sent over the bus.
1393 * \param dev_handle the device handle to close
1395 void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
1397 struct libusb_context *ctx;
1398 int handling_events;
1405 ctx = HANDLE_CTX(dev_handle);
1406 handling_events = usbi_handling_events(ctx);
1408 /* Similarly to libusb_open(), we want to interrupt all event handlers
1409 * at this point. More importantly, we want to perform the actual close of
1410 * the device while holding the event handling lock (preventing any other
1411 * thread from doing event handling) because we will be removing a file
1412 * descriptor from the polling loop. If this is being called by the current
1413 * event handler, we can bypass the interruption code because we already
1414 * hold the event handling lock. */
1416 if (!handling_events) {
1417 /* Record that we are closing a device.
1418 * Only signal an event if there are no prior pending events. */
1419 usbi_mutex_lock(&ctx->event_data_lock);
1420 pending_events = usbi_pending_events(ctx);
1421 ctx->device_close++;
1422 if (!pending_events)
1423 usbi_signal_event(ctx);
1424 usbi_mutex_unlock(&ctx->event_data_lock);
1426 /* take event handling lock */
1427 libusb_lock_events(ctx);
1430 /* Close the device */
1431 do_close(ctx, dev_handle);
1433 if (!handling_events) {
1434 /* We're done with closing this device.
1435 * Clear the event pipe if there are no further pending events. */
1436 usbi_mutex_lock(&ctx->event_data_lock);
1437 ctx->device_close--;
1438 pending_events = usbi_pending_events(ctx);
1439 if (!pending_events)
1440 usbi_clear_event(ctx);
1441 usbi_mutex_unlock(&ctx->event_data_lock);
1443 /* Release event handling lock and wake up event waiters */
1444 libusb_unlock_events(ctx);
1448 /** \ingroup libusb_dev
1449 * Get the underlying device for a device handle. This function does not modify
1450 * the reference count of the returned device, so do not feel compelled to
1451 * unreference it when you are done.
1452 * \param dev_handle a device handle
1453 * \returns the underlying device
1456 libusb_device * LIBUSB_CALL libusb_get_device(libusb_device_handle *dev_handle)
1458 return dev_handle->dev;
1461 /** \ingroup libusb_dev
1462 * Determine the bConfigurationValue of the currently active configuration.
1464 * You could formulate your own control request to obtain this information,
1465 * but this function has the advantage that it may be able to retrieve the
1466 * information from operating system caches (no I/O involved).
1468 * If the OS does not cache this information, then this function will block
1469 * while a control transfer is submitted to retrieve the information.
1471 * This function will return a value of 0 in the <tt>config</tt> output
1472 * parameter if the device is in unconfigured state.
1474 * \param dev_handle a device handle
1475 * \param config output location for the bConfigurationValue of the active
1476 * configuration (only valid for return code 0)
1477 * \returns 0 on success
1478 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1479 * \returns another LIBUSB_ERROR code on other failure
1481 int API_EXPORTED libusb_get_configuration(libusb_device_handle *dev_handle,
1484 int r = LIBUSB_ERROR_NOT_SUPPORTED;
1487 if (usbi_backend.get_configuration)
1488 r = usbi_backend.get_configuration(dev_handle, config);
1490 if (r == LIBUSB_ERROR_NOT_SUPPORTED) {
1492 usbi_dbg("falling back to control message");
1493 r = libusb_control_transfer(dev_handle, LIBUSB_ENDPOINT_IN,
1494 LIBUSB_REQUEST_GET_CONFIGURATION, 0, 0, &tmp, 1, 1000);
1496 usbi_err(HANDLE_CTX(dev_handle), "zero bytes returned in ctrl transfer?");
1497 r = LIBUSB_ERROR_IO;
1498 } else if (r == 1) {
1502 usbi_dbg("control failed, error %d", r);
1507 usbi_dbg("active config %d", *config);
1512 /** \ingroup libusb_dev
1513 * Set the active configuration for a device.
1515 * The operating system may or may not have already set an active
1516 * configuration on the device. It is up to your application to ensure the
1517 * correct configuration is selected before you attempt to claim interfaces
1518 * and perform other operations.
1520 * If you call this function on a device already configured with the selected
1521 * configuration, then this function will act as a lightweight device reset:
1522 * it will issue a SET_CONFIGURATION request using the current configuration,
1523 * causing most USB-related device state to be reset (altsetting reset to zero,
1524 * endpoint halts cleared, toggles reset).
1526 * You cannot change/reset configuration if your application has claimed
1527 * interfaces. It is advised to set the desired configuration before claiming
1530 * Alternatively you can call libusb_release_interface() first. Note if you
1531 * do things this way you must ensure that auto_detach_kernel_driver for
1532 * <tt>dev</tt> is 0, otherwise the kernel driver will be re-attached when you
1533 * release the interface(s).
1535 * You cannot change/reset configuration if other applications or drivers have
1536 * claimed interfaces.
1538 * A configuration value of -1 will put the device in unconfigured state.
1539 * The USB specifications state that a configuration value of 0 does this,
1540 * however buggy devices exist which actually have a configuration 0.
1542 * You should always use this function rather than formulating your own
1543 * SET_CONFIGURATION control request. This is because the underlying operating
1544 * system needs to know when such changes happen.
1546 * This is a blocking function.
1548 * \param dev_handle a device handle
1549 * \param configuration the bConfigurationValue of the configuration you
1550 * wish to activate, or -1 if you wish to put the device in an unconfigured
1552 * \returns 0 on success
1553 * \returns LIBUSB_ERROR_NOT_FOUND if the requested configuration does not exist
1554 * \returns LIBUSB_ERROR_BUSY if interfaces are currently claimed
1555 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1556 * \returns another LIBUSB_ERROR code on other failure
1557 * \see libusb_set_auto_detach_kernel_driver()
1559 int API_EXPORTED libusb_set_configuration(libusb_device_handle *dev_handle,
1562 usbi_dbg("configuration %d", configuration);
1563 return usbi_backend.set_configuration(dev_handle, configuration);
1566 /** \ingroup libusb_dev
1567 * Claim an interface on a given device handle. You must claim the interface
1568 * you wish to use before you can perform I/O on any of its endpoints.
1570 * It is legal to attempt to claim an already-claimed interface, in which
1571 * case libusb just returns 0 without doing anything.
1573 * If auto_detach_kernel_driver is set to 1 for <tt>dev</tt>, the kernel driver
1574 * will be detached if necessary, on failure the detach error is returned.
1576 * Claiming of interfaces is a purely logical operation; it does not cause
1577 * any requests to be sent over the bus. Interface claiming is used to
1578 * instruct the underlying operating system that your application wishes
1579 * to take ownership of the interface.
1581 * This is a non-blocking function.
1583 * \param dev_handle a device handle
1584 * \param interface_number the <tt>bInterfaceNumber</tt> of the interface you
1586 * \returns 0 on success
1587 * \returns LIBUSB_ERROR_NOT_FOUND if the requested interface does not exist
1588 * \returns LIBUSB_ERROR_BUSY if another program or driver has claimed the
1590 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1591 * \returns a LIBUSB_ERROR code on other failure
1592 * \see libusb_set_auto_detach_kernel_driver()
1594 int API_EXPORTED libusb_claim_interface(libusb_device_handle *dev_handle,
1595 int interface_number)
1599 usbi_dbg("interface %d", interface_number);
1600 if (interface_number >= USB_MAXINTERFACES)
1601 return LIBUSB_ERROR_INVALID_PARAM;
1603 if (!dev_handle->dev->attached)
1604 return LIBUSB_ERROR_NO_DEVICE;
1606 usbi_mutex_lock(&dev_handle->lock);
1607 if (dev_handle->claimed_interfaces & (1 << interface_number))
1610 r = usbi_backend.claim_interface(dev_handle, interface_number);
1612 dev_handle->claimed_interfaces |= 1 << interface_number;
1615 usbi_mutex_unlock(&dev_handle->lock);
1619 /** \ingroup libusb_dev
1620 * Release an interface previously claimed with libusb_claim_interface(). You
1621 * should release all claimed interfaces before closing a device handle.
1623 * This is a blocking function. A SET_INTERFACE control request will be sent
1624 * to the device, resetting interface state to the first alternate setting.
1626 * If auto_detach_kernel_driver is set to 1 for <tt>dev</tt>, the kernel
1627 * driver will be re-attached after releasing the interface.
1629 * \param dev_handle a device handle
1630 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1631 * previously-claimed interface
1632 * \returns 0 on success
1633 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed
1634 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1635 * \returns another LIBUSB_ERROR code on other failure
1636 * \see libusb_set_auto_detach_kernel_driver()
1638 int API_EXPORTED libusb_release_interface(libusb_device_handle *dev_handle,
1639 int interface_number)
1643 usbi_dbg("interface %d", interface_number);
1644 if (interface_number >= USB_MAXINTERFACES)
1645 return LIBUSB_ERROR_INVALID_PARAM;
1647 usbi_mutex_lock(&dev_handle->lock);
1648 if (!(dev_handle->claimed_interfaces & (1 << interface_number))) {
1649 r = LIBUSB_ERROR_NOT_FOUND;
1653 r = usbi_backend.release_interface(dev_handle, interface_number);
1655 dev_handle->claimed_interfaces &= ~(1 << interface_number);
1658 usbi_mutex_unlock(&dev_handle->lock);
1662 /** \ingroup libusb_dev
1663 * Activate an alternate setting for an interface. The interface must have
1664 * been previously claimed with libusb_claim_interface().
1666 * You should always use this function rather than formulating your own
1667 * SET_INTERFACE control request. This is because the underlying operating
1668 * system needs to know when such changes happen.
1670 * This is a blocking function.
1672 * \param dev_handle a device handle
1673 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1674 * previously-claimed interface
1675 * \param alternate_setting the <tt>bAlternateSetting</tt> of the alternate
1676 * setting to activate
1677 * \returns 0 on success
1678 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed, or the
1679 * requested alternate setting does not exist
1680 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1681 * \returns another LIBUSB_ERROR code on other failure
1683 int API_EXPORTED libusb_set_interface_alt_setting(libusb_device_handle *dev_handle,
1684 int interface_number, int alternate_setting)
1686 usbi_dbg("interface %d altsetting %d",
1687 interface_number, alternate_setting);
1688 if (interface_number >= USB_MAXINTERFACES)
1689 return LIBUSB_ERROR_INVALID_PARAM;
1691 usbi_mutex_lock(&dev_handle->lock);
1692 if (!dev_handle->dev->attached) {
1693 usbi_mutex_unlock(&dev_handle->lock);
1694 return LIBUSB_ERROR_NO_DEVICE;
1697 if (!(dev_handle->claimed_interfaces & (1 << interface_number))) {
1698 usbi_mutex_unlock(&dev_handle->lock);
1699 return LIBUSB_ERROR_NOT_FOUND;
1701 usbi_mutex_unlock(&dev_handle->lock);
1703 return usbi_backend.set_interface_altsetting(dev_handle, interface_number,
1707 /** \ingroup libusb_dev
1708 * Clear the halt/stall condition for an endpoint. Endpoints with halt status
1709 * are unable to receive or transmit data until the halt condition is stalled.
1711 * You should cancel all pending transfers before attempting to clear the halt
1714 * This is a blocking function.
1716 * \param dev_handle a device handle
1717 * \param endpoint the endpoint to clear halt status
1718 * \returns 0 on success
1719 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
1720 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1721 * \returns another LIBUSB_ERROR code on other failure
1723 int API_EXPORTED libusb_clear_halt(libusb_device_handle *dev_handle,
1724 unsigned char endpoint)
1726 usbi_dbg("endpoint %x", endpoint);
1727 if (!dev_handle->dev->attached)
1728 return LIBUSB_ERROR_NO_DEVICE;
1730 return usbi_backend.clear_halt(dev_handle, endpoint);
1733 /** \ingroup libusb_dev
1734 * Perform a USB port reset to reinitialize a device. The system will attempt
1735 * to restore the previous configuration and alternate settings after the
1736 * reset has completed.
1738 * If the reset fails, the descriptors change, or the previous state cannot be
1739 * restored, the device will appear to be disconnected and reconnected. This
1740 * means that the device handle is no longer valid (you should close it) and
1741 * rediscover the device. A return code of LIBUSB_ERROR_NOT_FOUND indicates
1742 * when this is the case.
1744 * This is a blocking function which usually incurs a noticeable delay.
1746 * \param dev_handle a handle of the device to reset
1747 * \returns 0 on success
1748 * \returns LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the
1749 * device has been disconnected
1750 * \returns another LIBUSB_ERROR code on other failure
1752 int API_EXPORTED libusb_reset_device(libusb_device_handle *dev_handle)
1755 if (!dev_handle->dev->attached)
1756 return LIBUSB_ERROR_NO_DEVICE;
1758 return usbi_backend.reset_device(dev_handle);
1761 /** \ingroup libusb_asyncio
1762 * Allocate up to num_streams usb bulk streams on the specified endpoints. This
1763 * function takes an array of endpoints rather then a single endpoint because
1764 * some protocols require that endpoints are setup with similar stream ids.
1765 * All endpoints passed in must belong to the same interface.
1767 * Note this function may return less streams then requested. Also note that the
1768 * same number of streams are allocated for each endpoint in the endpoint array.
1770 * Stream id 0 is reserved, and should not be used to communicate with devices.
1771 * If libusb_alloc_streams() returns with a value of N, you may use stream ids
1774 * Since version 1.0.19, \ref LIBUSB_API_VERSION >= 0x01000103
1776 * \param dev_handle a device handle
1777 * \param num_streams number of streams to try to allocate
1778 * \param endpoints array of endpoints to allocate streams on
1779 * \param num_endpoints length of the endpoints array
1780 * \returns number of streams allocated, or a LIBUSB_ERROR code on failure
1782 int API_EXPORTED libusb_alloc_streams(libusb_device_handle *dev_handle,
1783 uint32_t num_streams, unsigned char *endpoints, int num_endpoints)
1785 usbi_dbg("streams %u eps %d", (unsigned) num_streams, num_endpoints);
1787 if (!dev_handle->dev->attached)
1788 return LIBUSB_ERROR_NO_DEVICE;
1790 if (usbi_backend.alloc_streams)
1791 return usbi_backend.alloc_streams(dev_handle, num_streams, endpoints,
1794 return LIBUSB_ERROR_NOT_SUPPORTED;
1797 /** \ingroup libusb_asyncio
1798 * Free usb bulk streams allocated with libusb_alloc_streams().
1800 * Note streams are automatically free-ed when releasing an interface.
1802 * Since version 1.0.19, \ref LIBUSB_API_VERSION >= 0x01000103
1804 * \param dev_handle a device handle
1805 * \param endpoints array of endpoints to free streams on
1806 * \param num_endpoints length of the endpoints array
1807 * \returns LIBUSB_SUCCESS, or a LIBUSB_ERROR code on failure
1809 int API_EXPORTED libusb_free_streams(libusb_device_handle *dev_handle,
1810 unsigned char *endpoints, int num_endpoints)
1812 usbi_dbg("eps %d", num_endpoints);
1814 if (!dev_handle->dev->attached)
1815 return LIBUSB_ERROR_NO_DEVICE;
1817 if (usbi_backend.free_streams)
1818 return usbi_backend.free_streams(dev_handle, endpoints,
1821 return LIBUSB_ERROR_NOT_SUPPORTED;
1824 /** \ingroup libusb_asyncio
1825 * Attempts to allocate a block of persistent DMA memory suitable for transfers
1826 * against the given device. If successful, will return a block of memory
1827 * that is suitable for use as "buffer" in \ref libusb_transfer against this
1828 * device. Using this memory instead of regular memory means that the host
1829 * controller can use DMA directly into the buffer to increase performance, and
1830 * also that transfers can no longer fail due to kernel memory fragmentation.
1832 * Note that this means you should not modify this memory (or even data on
1833 * the same cache lines) when a transfer is in progress, although it is legal
1834 * to have several transfers going on within the same memory block.
1836 * Will return NULL on failure. Many systems do not support such zerocopy
1837 * and will always return NULL. Memory allocated with this function must be
1838 * freed with \ref libusb_dev_mem_free. Specifically, this means that the
1839 * flag \ref LIBUSB_TRANSFER_FREE_BUFFER cannot be used to free memory allocated
1840 * with this function.
1842 * Since version 1.0.21, \ref LIBUSB_API_VERSION >= 0x01000105
1844 * \param dev_handle a device handle
1845 * \param length size of desired data buffer
1846 * \returns a pointer to the newly allocated memory, or NULL on failure
1849 unsigned char * LIBUSB_CALL libusb_dev_mem_alloc(libusb_device_handle *dev_handle,
1852 if (!dev_handle->dev->attached)
1855 if (usbi_backend.dev_mem_alloc)
1856 return usbi_backend.dev_mem_alloc(dev_handle, length);
1861 /** \ingroup libusb_asyncio
1862 * Free device memory allocated with libusb_dev_mem_alloc().
1864 * \param dev_handle a device handle
1865 * \param buffer pointer to the previously allocated memory
1866 * \param length size of previously allocated memory
1867 * \returns LIBUSB_SUCCESS, or a LIBUSB_ERROR code on failure
1869 int API_EXPORTED libusb_dev_mem_free(libusb_device_handle *dev_handle,
1870 unsigned char *buffer, size_t length)
1872 if (usbi_backend.dev_mem_free)
1873 return usbi_backend.dev_mem_free(dev_handle, buffer, length);
1875 return LIBUSB_ERROR_NOT_SUPPORTED;
1878 /** \ingroup libusb_dev
1879 * Determine if a kernel driver is active on an interface. If a kernel driver
1880 * is active, you cannot claim the interface, and libusb will be unable to
1883 * This functionality is not available on Windows.
1885 * \param dev_handle a device handle
1886 * \param interface_number the interface to check
1887 * \returns 0 if no kernel driver is active
1888 * \returns 1 if a kernel driver is active
1889 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1890 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1892 * \returns another LIBUSB_ERROR code on other failure
1893 * \see libusb_detach_kernel_driver()
1895 int API_EXPORTED libusb_kernel_driver_active(libusb_device_handle *dev_handle,
1896 int interface_number)
1898 usbi_dbg("interface %d", interface_number);
1900 if (!dev_handle->dev->attached)
1901 return LIBUSB_ERROR_NO_DEVICE;
1903 if (usbi_backend.kernel_driver_active)
1904 return usbi_backend.kernel_driver_active(dev_handle, interface_number);
1906 return LIBUSB_ERROR_NOT_SUPPORTED;
1909 /** \ingroup libusb_dev
1910 * Detach a kernel driver from an interface. If successful, you will then be
1911 * able to claim the interface and perform I/O.
1913 * This functionality is not available on Darwin or Windows.
1915 * Note that libusb itself also talks to the device through a special kernel
1916 * driver, if this driver is already attached to the device, this call will
1917 * not detach it and return LIBUSB_ERROR_NOT_FOUND.
1919 * \param dev_handle a device handle
1920 * \param interface_number the interface to detach the driver from
1921 * \returns 0 on success
1922 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1923 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1924 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1925 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1927 * \returns another LIBUSB_ERROR code on other failure
1928 * \see libusb_kernel_driver_active()
1930 int API_EXPORTED libusb_detach_kernel_driver(libusb_device_handle *dev_handle,
1931 int interface_number)
1933 usbi_dbg("interface %d", interface_number);
1935 if (!dev_handle->dev->attached)
1936 return LIBUSB_ERROR_NO_DEVICE;
1938 if (usbi_backend.detach_kernel_driver)
1939 return usbi_backend.detach_kernel_driver(dev_handle, interface_number);
1941 return LIBUSB_ERROR_NOT_SUPPORTED;
1944 /** \ingroup libusb_dev
1945 * Re-attach an interface's kernel driver, which was previously detached
1946 * using libusb_detach_kernel_driver(). This call is only effective on
1947 * Linux and returns LIBUSB_ERROR_NOT_SUPPORTED on all other platforms.
1949 * This functionality is not available on Darwin or Windows.
1951 * \param dev_handle a device handle
1952 * \param interface_number the interface to attach the driver from
1953 * \returns 0 on success
1954 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1955 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1956 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1957 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1959 * \returns LIBUSB_ERROR_BUSY if the driver cannot be attached because the
1960 * interface is claimed by a program or driver
1961 * \returns another LIBUSB_ERROR code on other failure
1962 * \see libusb_kernel_driver_active()
1964 int API_EXPORTED libusb_attach_kernel_driver(libusb_device_handle *dev_handle,
1965 int interface_number)
1967 usbi_dbg("interface %d", interface_number);
1969 if (!dev_handle->dev->attached)
1970 return LIBUSB_ERROR_NO_DEVICE;
1972 if (usbi_backend.attach_kernel_driver)
1973 return usbi_backend.attach_kernel_driver(dev_handle, interface_number);
1975 return LIBUSB_ERROR_NOT_SUPPORTED;
1978 /** \ingroup libusb_dev
1979 * Enable/disable libusb's automatic kernel driver detachment. When this is
1980 * enabled libusb will automatically detach the kernel driver on an interface
1981 * when claiming the interface, and attach it when releasing the interface.
1983 * Automatic kernel driver detachment is disabled on newly opened device
1984 * handles by default.
1986 * On platforms which do not have LIBUSB_CAP_SUPPORTS_DETACH_KERNEL_DRIVER
1987 * this function will return LIBUSB_ERROR_NOT_SUPPORTED, and libusb will
1988 * continue as if this function was never called.
1990 * \param dev_handle a device handle
1991 * \param enable whether to enable or disable auto kernel driver detachment
1993 * \returns LIBUSB_SUCCESS on success
1994 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1996 * \see libusb_claim_interface()
1997 * \see libusb_release_interface()
1998 * \see libusb_set_configuration()
2000 int API_EXPORTED libusb_set_auto_detach_kernel_driver(
2001 libusb_device_handle *dev_handle, int enable)
2003 if (!(usbi_backend.caps & USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER))
2004 return LIBUSB_ERROR_NOT_SUPPORTED;
2006 dev_handle->auto_detach_kernel_driver = enable;
2007 return LIBUSB_SUCCESS;
2010 /** \ingroup libusb_lib
2011 * \deprecated Use libusb_set_option() instead using the
2012 * \ref LIBUSB_OPTION_LOG_LEVEL option.
2014 void API_EXPORTED libusb_set_debug(libusb_context *ctx, int level)
2016 #if defined(ENABLE_LOGGING) && !defined(ENABLE_DEBUG_LOGGING)
2017 USBI_GET_CONTEXT(ctx);
2018 if (!ctx->debug_fixed) {
2019 level = CLAMP(level, LIBUSB_LOG_LEVEL_NONE, LIBUSB_LOG_LEVEL_DEBUG);
2020 ctx->debug = (enum libusb_log_level)level;
2028 /** \ingroup libusb_lib
2029 * Set an option in the library.
2031 * Use this function to configure a specific option within the library.
2033 * Some options require one or more arguments to be provided. Consult each
2034 * option's documentation for specific requirements.
2036 * Since version 1.0.22, \ref LIBUSB_API_VERSION >= 0x01000106
2038 * \param ctx context on which to operate
2039 * \param option which option to set
2040 * \param ... any required arguments for the specified option
2042 * \returns LIBUSB_SUCCESS on success
2043 * \returns LIBUSB_ERROR_INVALID_PARAM if the option or arguments are invalid
2044 * \returns LIBUSB_ERROR_NOT_SUPPORTED if the option is valid but not supported
2047 int API_EXPORTED libusb_set_option(libusb_context *ctx,
2048 enum libusb_option option, ...)
2050 int arg, r = LIBUSB_SUCCESS;
2053 USBI_GET_CONTEXT(ctx);
2055 va_start(ap, option);
2057 case LIBUSB_OPTION_LOG_LEVEL:
2058 arg = va_arg(ap, int);
2059 if (arg < LIBUSB_LOG_LEVEL_NONE || arg > LIBUSB_LOG_LEVEL_DEBUG) {
2060 r = LIBUSB_ERROR_INVALID_PARAM;
2063 #if defined(ENABLE_LOGGING) && !defined(ENABLE_DEBUG_LOGGING)
2064 if (!ctx->debug_fixed)
2065 ctx->debug = (enum libusb_log_level)arg;
2069 /* Handle all backend-specific options here */
2070 case LIBUSB_OPTION_USE_USBDK:
2071 if (usbi_backend.set_option)
2072 r = usbi_backend.set_option(ctx, option, ap);
2074 r = LIBUSB_ERROR_NOT_SUPPORTED;
2078 r = LIBUSB_ERROR_INVALID_PARAM;
2085 #if defined(ENABLE_LOGGING) && !defined(ENABLE_DEBUG_LOGGING)
2086 /* returns the log level as defined in the LIBUSB_DEBUG environment variable.
2087 * if LIBUSB_DEBUG is not present or not a number, returns LIBUSB_LOG_LEVEL_NONE.
2088 * value is clamped to ensure it is within the valid range of possibilities.
2090 static enum libusb_log_level get_env_debug_level(void)
2092 const char *dbg = getenv("LIBUSB_DEBUG");
2093 enum libusb_log_level level;
2095 int dbg_level = atoi(dbg);
2096 dbg_level = CLAMP(dbg_level, LIBUSB_LOG_LEVEL_NONE, LIBUSB_LOG_LEVEL_DEBUG);
2097 level = (enum libusb_log_level)dbg_level;
2099 level = LIBUSB_LOG_LEVEL_NONE;
2105 /** \ingroup libusb_lib
2106 * Initialize libusb. This function must be called before calling any other
2109 * If you do not provide an output location for a context pointer, a default
2110 * context will be created. If there was already a default context, it will
2111 * be reused (and nothing will be initialized/reinitialized).
2113 * \param context Optional output location for context pointer.
2114 * Only valid on return code 0.
2115 * \returns 0 on success, or a LIBUSB_ERROR code on failure
2116 * \see libusb_contexts
2118 int API_EXPORTED libusb_init(libusb_context **context)
2120 struct libusb_device *dev, *next;
2121 size_t priv_size = usbi_backend.context_priv_size;
2122 struct libusb_context *ctx;
2123 static int first_init = 1;
2126 usbi_mutex_static_lock(&default_context_lock);
2128 if (!timestamp_origin.tv_sec) {
2129 usbi_backend.clock_gettime(USBI_CLOCK_REALTIME, ×tamp_origin);
2132 if (!context && usbi_default_context) {
2133 usbi_dbg("reusing default context");
2134 default_context_refcnt++;
2135 usbi_mutex_static_unlock(&default_context_lock);
2139 ctx = calloc(1, sizeof(*ctx) + priv_size);
2141 r = LIBUSB_ERROR_NO_MEM;
2145 #if defined(ENABLE_LOGGING) && !defined(ENABLE_DEBUG_LOGGING)
2146 ctx->debug = get_env_debug_level();
2147 if (ctx->debug != LIBUSB_LOG_LEVEL_NONE)
2148 ctx->debug_fixed = 1;
2151 /* default context should be initialized before calling usbi_dbg */
2152 if (!usbi_default_context) {
2153 usbi_default_context = ctx;
2154 default_context_refcnt++;
2155 usbi_dbg("created default context");
2158 usbi_dbg("libusb v%u.%u.%u.%u%s", libusb_version_internal.major, libusb_version_internal.minor,
2159 libusb_version_internal.micro, libusb_version_internal.nano, libusb_version_internal.rc);
2161 usbi_mutex_init(&ctx->usb_devs_lock);
2162 usbi_mutex_init(&ctx->open_devs_lock);
2163 usbi_mutex_init(&ctx->hotplug_cbs_lock);
2164 list_init(&ctx->usb_devs);
2165 list_init(&ctx->open_devs);
2166 list_init(&ctx->hotplug_cbs);
2167 ctx->next_hotplug_cb_handle = 1;
2169 usbi_mutex_static_lock(&active_contexts_lock);
2172 list_init (&active_contexts_list);
2174 list_add (&ctx->list, &active_contexts_list);
2175 usbi_mutex_static_unlock(&active_contexts_lock);
2177 if (usbi_backend.init) {
2178 r = usbi_backend.init(ctx);
2183 r = usbi_io_init(ctx);
2185 goto err_backend_exit;
2187 usbi_mutex_static_unlock(&default_context_lock);
2195 if (usbi_backend.exit)
2196 usbi_backend.exit(ctx);
2198 if (ctx == usbi_default_context) {
2199 usbi_default_context = NULL;
2200 default_context_refcnt--;
2203 usbi_mutex_static_lock(&active_contexts_lock);
2204 list_del (&ctx->list);
2205 usbi_mutex_static_unlock(&active_contexts_lock);
2207 usbi_mutex_lock(&ctx->usb_devs_lock);
2208 list_for_each_entry_safe(dev, next, &ctx->usb_devs, list, struct libusb_device) {
2209 list_del(&dev->list);
2210 libusb_unref_device(dev);
2212 usbi_mutex_unlock(&ctx->usb_devs_lock);
2214 usbi_mutex_destroy(&ctx->open_devs_lock);
2215 usbi_mutex_destroy(&ctx->usb_devs_lock);
2216 usbi_mutex_destroy(&ctx->hotplug_cbs_lock);
2220 usbi_mutex_static_unlock(&default_context_lock);
2224 /** \ingroup libusb_lib
2225 * Deinitialize libusb. Should be called after closing all open devices and
2226 * before your application terminates.
2227 * \param ctx the context to deinitialize, or NULL for the default context
2229 void API_EXPORTED libusb_exit(struct libusb_context *ctx)
2231 struct libusb_device *dev, *next;
2232 struct timeval tv = { 0, 0 };
2235 USBI_GET_CONTEXT(ctx);
2237 /* if working with default context, only actually do the deinitialization
2238 * if we're the last user */
2239 usbi_mutex_static_lock(&default_context_lock);
2240 if (ctx == usbi_default_context) {
2241 if (--default_context_refcnt > 0) {
2242 usbi_dbg("not destroying default context");
2243 usbi_mutex_static_unlock(&default_context_lock);
2246 usbi_dbg("destroying default context");
2247 usbi_default_context = NULL;
2249 usbi_mutex_static_unlock(&default_context_lock);
2251 usbi_mutex_static_lock(&active_contexts_lock);
2252 list_del (&ctx->list);
2253 usbi_mutex_static_unlock(&active_contexts_lock);
2255 if (libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
2256 usbi_hotplug_deregister(ctx, 1);
2259 * Ensure any pending unplug events are read from the hotplug
2260 * pipe. The usb_device-s hold in the events are no longer part
2261 * of usb_devs, but the events still hold a reference!
2263 * Note we don't do this if the application has left devices
2264 * open (which implies a buggy app) to avoid packet completion
2265 * handlers running when the app does not expect them to run.
2267 if (list_empty(&ctx->open_devs))
2268 libusb_handle_events_timeout(ctx, &tv);
2270 usbi_mutex_lock(&ctx->usb_devs_lock);
2271 list_for_each_entry_safe(dev, next, &ctx->usb_devs, list, struct libusb_device) {
2272 list_del(&dev->list);
2273 libusb_unref_device(dev);
2275 usbi_mutex_unlock(&ctx->usb_devs_lock);
2278 /* a few sanity checks. don't bother with locking because unless
2279 * there is an application bug, nobody will be accessing these. */
2280 if (!list_empty(&ctx->usb_devs))
2281 usbi_warn(ctx, "some libusb_devices were leaked");
2282 if (!list_empty(&ctx->open_devs))
2283 usbi_warn(ctx, "application left some devices open");
2286 if (usbi_backend.exit)
2287 usbi_backend.exit(ctx);
2289 usbi_mutex_destroy(&ctx->open_devs_lock);
2290 usbi_mutex_destroy(&ctx->usb_devs_lock);
2291 usbi_mutex_destroy(&ctx->hotplug_cbs_lock);
2295 /** \ingroup libusb_misc
2296 * Check at runtime if the loaded library has a given capability.
2297 * This call should be performed after \ref libusb_init(), to ensure the
2298 * backend has updated its capability set.
2300 * \param capability the \ref libusb_capability to check for
2301 * \returns nonzero if the running library has the capability, 0 otherwise
2303 int API_EXPORTED libusb_has_capability(uint32_t capability)
2305 switch (capability) {
2306 case LIBUSB_CAP_HAS_CAPABILITY:
2308 case LIBUSB_CAP_HAS_HOTPLUG:
2309 return !(usbi_backend.get_device_list);
2310 case LIBUSB_CAP_HAS_HID_ACCESS:
2311 return (usbi_backend.caps & USBI_CAP_HAS_HID_ACCESS);
2312 case LIBUSB_CAP_SUPPORTS_DETACH_KERNEL_DRIVER:
2313 return (usbi_backend.caps & USBI_CAP_SUPPORTS_DETACH_KERNEL_DRIVER);
2318 #ifdef ENABLE_LOGGING
2320 /* this is defined in libusbi.h if needed */
2321 #ifdef LIBUSB_PRINTF_WIN32
2323 * Prior to VS2015, Microsoft did not provide the snprintf() function and
2324 * provided a vsnprintf() that did not guarantee NULL-terminated output.
2325 * Microsoft did provide a _snprintf() function, but again it did not
2326 * guarantee NULL-terminated output.
2328 * The below implementations guarantee NULL-terminated output and are
2332 int usbi_snprintf(char *str, size_t size, const char *format, ...)
2337 va_start(ap, format);
2338 ret = usbi_vsnprintf(str, size, format, ap);
2344 int usbi_vsnprintf(char *str, size_t size, const char *format, va_list ap)
2348 ret = _vsnprintf(str, size, format, ap);
2349 if (ret < 0 || ret == (int)size) {
2350 /* Output is truncated, ensure buffer is NULL-terminated and
2351 * determine how many characters would have been written. */
2352 str[size - 1] = '\0';
2354 ret = _vsnprintf(NULL, 0, format, ap);
2359 #endif /* LIBUSB_PRINTF_WIN32 */
2361 static void usbi_log_str(enum libusb_log_level level, const char *str)
2363 #if defined(USE_SYSTEM_LOGGING_FACILITY)
2364 #if defined(OS_WINDOWS)
2365 OutputDebugString(str);
2366 #elif defined(OS_WINCE)
2367 /* Windows CE only supports the Unicode version of OutputDebugString. */
2368 WCHAR wbuf[USBI_MAX_LOG_LEN];
2369 MultiByteToWideChar(CP_UTF8, 0, str, -1, wbuf, sizeof(wbuf));
2370 OutputDebugStringW(wbuf);
2371 #elif defined(__ANDROID__)
2372 int priority = ANDROID_LOG_UNKNOWN;
2374 case LIBUSB_LOG_LEVEL_NONE: return;
2375 case LIBUSB_LOG_LEVEL_ERROR: priority = ANDROID_LOG_ERROR; break;
2376 case LIBUSB_LOG_LEVEL_WARNING: priority = ANDROID_LOG_WARN; break;
2377 case LIBUSB_LOG_LEVEL_INFO: priority = ANDROID_LOG_INFO; break;
2378 case LIBUSB_LOG_LEVEL_DEBUG: priority = ANDROID_LOG_DEBUG; break;
2380 __android_log_write(priority, "libusb", str);
2381 #elif defined(HAVE_SYSLOG_FUNC)
2382 int syslog_level = LOG_INFO;
2384 case LIBUSB_LOG_LEVEL_NONE: return;
2385 case LIBUSB_LOG_LEVEL_ERROR: syslog_level = LOG_ERR; break;
2386 case LIBUSB_LOG_LEVEL_WARNING: syslog_level = LOG_WARNING; break;
2387 case LIBUSB_LOG_LEVEL_INFO: syslog_level = LOG_INFO; break;
2388 case LIBUSB_LOG_LEVEL_DEBUG: syslog_level = LOG_DEBUG; break;
2390 syslog(syslog_level, "%s", str);
2391 #else /* All of gcc, Clang, XCode seem to use #warning */
2392 #warning System logging is not supported on this platform. Logging to stderr will be used instead.
2397 #endif /* USE_SYSTEM_LOGGING_FACILITY */
2401 void usbi_log_v(struct libusb_context *ctx, enum libusb_log_level level,
2402 const char *function, const char *format, va_list args)
2405 char buf[USBI_MAX_LOG_LEN];
2406 struct timespec now;
2407 int global_debug, header_len, text_len;
2408 static int has_debug_header_been_displayed = 0;
2410 #ifdef ENABLE_DEBUG_LOGGING
2414 enum libusb_log_level ctx_level = LIBUSB_LOG_LEVEL_NONE;
2416 USBI_GET_CONTEXT(ctx);
2418 ctx_level = ctx->debug;
2420 ctx_level = get_env_debug_level();
2422 if (ctx_level == LIBUSB_LOG_LEVEL_NONE)
2424 if (level == LIBUSB_LOG_LEVEL_WARNING && ctx_level < LIBUSB_LOG_LEVEL_WARNING)
2426 if (level == LIBUSB_LOG_LEVEL_INFO && ctx_level < LIBUSB_LOG_LEVEL_INFO)
2428 if (level == LIBUSB_LOG_LEVEL_DEBUG && ctx_level < LIBUSB_LOG_LEVEL_DEBUG)
2431 global_debug = (ctx_level == LIBUSB_LOG_LEVEL_DEBUG);
2434 usbi_backend.clock_gettime(USBI_CLOCK_REALTIME, &now);
2435 if ((global_debug) && (!has_debug_header_been_displayed)) {
2436 has_debug_header_been_displayed = 1;
2437 usbi_log_str(LIBUSB_LOG_LEVEL_DEBUG, "[timestamp] [threadID] facility level [function call] <message>" USBI_LOG_LINE_END);
2438 usbi_log_str(LIBUSB_LOG_LEVEL_DEBUG, "--------------------------------------------------------------------------------" USBI_LOG_LINE_END);
2440 if (now.tv_nsec < timestamp_origin.tv_nsec) {
2442 now.tv_nsec += 1000000000L;
2444 now.tv_sec -= timestamp_origin.tv_sec;
2445 now.tv_nsec -= timestamp_origin.tv_nsec;
2448 case LIBUSB_LOG_LEVEL_NONE:
2450 case LIBUSB_LOG_LEVEL_ERROR:
2453 case LIBUSB_LOG_LEVEL_WARNING:
2456 case LIBUSB_LOG_LEVEL_INFO:
2459 case LIBUSB_LOG_LEVEL_DEBUG:
2468 header_len = snprintf(buf, sizeof(buf),
2469 "[%2d.%06d] [%08x] libusb: %s [%s] ",
2470 (int)now.tv_sec, (int)(now.tv_nsec / 1000L), usbi_get_tid(), prefix, function);
2472 header_len = snprintf(buf, sizeof(buf),
2473 "libusb: %s [%s] ", prefix, function);
2476 if (header_len < 0 || header_len >= (int)sizeof(buf)) {
2477 /* Somehow snprintf failed to write to the buffer,
2478 * remove the header so something useful is output. */
2481 /* Make sure buffer is NUL terminated */
2482 buf[header_len] = '\0';
2483 text_len = vsnprintf(buf + header_len, sizeof(buf) - header_len,
2485 if (text_len < 0 || text_len + header_len >= (int)sizeof(buf)) {
2486 /* Truncated log output. On some platforms a -1 return value means
2487 * that the output was truncated. */
2488 text_len = sizeof(buf) - header_len;
2490 if (header_len + text_len + sizeof(USBI_LOG_LINE_END) >= sizeof(buf)) {
2491 /* Need to truncate the text slightly to fit on the terminator. */
2492 text_len -= (header_len + text_len + sizeof(USBI_LOG_LINE_END)) - sizeof(buf);
2494 strcpy(buf + header_len + text_len, USBI_LOG_LINE_END);
2496 usbi_log_str(level, buf);
2499 void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
2500 const char *function, const char *format, ...)
2504 va_start (args, format);
2505 usbi_log_v(ctx, level, function, format, args);
2509 #endif /* ENABLE_LOGGING */
2511 /** \ingroup libusb_misc
2512 * Returns a constant NULL-terminated string with the ASCII name of a libusb
2513 * error or transfer status code. The caller must not free() the returned
2516 * \param error_code The \ref libusb_error or libusb_transfer_status code to
2517 * return the name of.
2518 * \returns The error name, or the string **UNKNOWN** if the value of
2519 * error_code is not a known error / status code.
2521 DEFAULT_VISIBILITY const char * LIBUSB_CALL libusb_error_name(int error_code)
2523 switch (error_code) {
2524 case LIBUSB_ERROR_IO:
2525 return "LIBUSB_ERROR_IO";
2526 case LIBUSB_ERROR_INVALID_PARAM:
2527 return "LIBUSB_ERROR_INVALID_PARAM";
2528 case LIBUSB_ERROR_ACCESS:
2529 return "LIBUSB_ERROR_ACCESS";
2530 case LIBUSB_ERROR_NO_DEVICE:
2531 return "LIBUSB_ERROR_NO_DEVICE";
2532 case LIBUSB_ERROR_NOT_FOUND:
2533 return "LIBUSB_ERROR_NOT_FOUND";
2534 case LIBUSB_ERROR_BUSY:
2535 return "LIBUSB_ERROR_BUSY";
2536 case LIBUSB_ERROR_TIMEOUT:
2537 return "LIBUSB_ERROR_TIMEOUT";
2538 case LIBUSB_ERROR_OVERFLOW:
2539 return "LIBUSB_ERROR_OVERFLOW";
2540 case LIBUSB_ERROR_PIPE:
2541 return "LIBUSB_ERROR_PIPE";
2542 case LIBUSB_ERROR_INTERRUPTED:
2543 return "LIBUSB_ERROR_INTERRUPTED";
2544 case LIBUSB_ERROR_NO_MEM:
2545 return "LIBUSB_ERROR_NO_MEM";
2546 case LIBUSB_ERROR_NOT_SUPPORTED:
2547 return "LIBUSB_ERROR_NOT_SUPPORTED";
2548 case LIBUSB_ERROR_OTHER:
2549 return "LIBUSB_ERROR_OTHER";
2551 case LIBUSB_TRANSFER_ERROR:
2552 return "LIBUSB_TRANSFER_ERROR";
2553 case LIBUSB_TRANSFER_TIMED_OUT:
2554 return "LIBUSB_TRANSFER_TIMED_OUT";
2555 case LIBUSB_TRANSFER_CANCELLED:
2556 return "LIBUSB_TRANSFER_CANCELLED";
2557 case LIBUSB_TRANSFER_STALL:
2558 return "LIBUSB_TRANSFER_STALL";
2559 case LIBUSB_TRANSFER_NO_DEVICE:
2560 return "LIBUSB_TRANSFER_NO_DEVICE";
2561 case LIBUSB_TRANSFER_OVERFLOW:
2562 return "LIBUSB_TRANSFER_OVERFLOW";
2565 return "LIBUSB_SUCCESS / LIBUSB_TRANSFER_COMPLETED";
2567 return "**UNKNOWN**";
2571 /** \ingroup libusb_misc
2572 * Returns a pointer to const struct libusb_version with the version
2573 * (major, minor, micro, nano and rc) of the running library.
2576 const struct libusb_version * LIBUSB_CALL libusb_get_version(void)
2578 return &libusb_version_internal;