2 * Core functions for libusbx
3 * Copyright © 2007-2008 Daniel Drake <dsd@gentoo.org>
4 * Copyright © 2001 Johannes Erdfelt <johannes@erdfelt.com>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28 #include <sys/types.h>
30 #ifdef HAVE_SYS_TIME_H
37 const struct usbi_os_backend * const usbi_backend = &linux_usbfs_backend;
38 #elif defined(OS_DARWIN)
39 const struct usbi_os_backend * const usbi_backend = &darwin_backend;
40 #elif defined(OS_OPENBSD)
41 const struct usbi_os_backend * const usbi_backend = &openbsd_backend;
42 #elif defined(OS_WINDOWS)
43 const struct usbi_os_backend * const usbi_backend = &windows_backend;
45 #error "Unsupported OS"
48 struct libusb_context *usbi_default_context = NULL;
49 const struct libusb_version libusb_version_internal =
50 { LIBUSB_MAJOR, LIBUSB_MINOR, LIBUSB_MICRO, LIBUSB_NANO,
51 LIBUSB_RC, "unused - please use the nano" };
52 static int default_context_refcnt = 0;
53 static usbi_mutex_static_t default_context_lock = USBI_MUTEX_INITIALIZER;
54 static struct timeval timestamp_origin = { 0, 0 };
57 * \mainpage libusbx-1.0 API Reference
59 * \section intro Introduction
61 * libusbx is an open source library that allows you to communicate with USB
62 * devices from userspace. For more info, see the
63 * <a href="http://libusbx.sourceforge.net">libusbx homepage</a>.
65 * This documentation is aimed at application developers wishing to
66 * communicate with USB peripherals from their own software. After reviewing
67 * this documentation, feedback and questions can be sent to the
68 * <a href="https://lists.sourceforge.net/lists/listinfo/libusbx-devel">libusbx-devel mailing
71 * This documentation assumes knowledge of how to operate USB devices from
72 * a software standpoint (descriptors, configurations, interfaces, endpoints,
73 * control/bulk/interrupt/isochronous transfers, etc). Full information
74 * can be found in the <a href="http://www.usb.org/developers/docs/">USB 3.0
75 * Specification</a> which is available for free download. You can probably
76 * find less verbose introductions by searching the web.
78 * \section features Library features
80 * - All transfer types supported (control/bulk/interrupt/isochronous)
81 * - 2 transfer interfaces:
82 * -# Synchronous (simple)
83 * -# Asynchronous (more complicated, but more powerful)
84 * - Thread safe (although the asynchronous interface means that you
85 * usually won't need to thread)
86 * - Lightweight with lean API
87 * - Compatible with libusb-0.1 through the libusb-compat-0.1 translation layer
89 * \section gettingstarted Getting Started
91 * To begin reading the API documentation, start with the Modules page which
92 * links to the different categories of libusbx's functionality.
94 * One decision you will have to make is whether to use the synchronous
95 * or the asynchronous data transfer interface. The \ref io documentation
96 * provides some insight into this topic.
98 * Some example programs can be found in the libusbx source distribution under
99 * the "examples" subdirectory. The libusbx homepage includes a list of
100 * real-life project examples which use libusbx.
102 * \section errorhandling Error handling
104 * libusbx functions typically return 0 on success or a negative error code
105 * on failure. These negative error codes relate to LIBUSB_ERROR constants
106 * which are listed on the \ref misc "miscellaneous" documentation page.
108 * \section msglog Debug message logging
110 * libusbx does not log any messages by default. Your application is therefore
111 * free to close stdout/stderr and those descriptors may be reused without
114 * The libusb_set_debug() function can be used to enable stderr logging of
115 * certain messages. Under standard configuration, libusbx doesn't really
116 * log much at all, so you are advised to use this function to enable all
117 * error/warning/informational messages. It will help you debug problems with
120 * The logged messages are unstructured. There is no one-to-one correspondence
121 * between messages being logged and success or failure return codes from
122 * libusbx functions. There is no format to the messages, so you should not
123 * try to capture or parse them. They are not and will not be localized.
124 * These messages are not intended to being passed to your application user;
125 * instead, you should interpret the error codes returned from libusbx functions
126 * and provide appropriate notification to the user. The messages are simply
127 * there to aid you as a programmer, and if you're confused because you're
128 * getting a strange error code from a libusbx function, enabling message
129 * logging may give you a suitable explanation.
131 * The LIBUSB_DEBUG environment variable can be used to enable message logging
132 * at run-time. This environment variable should be set to a log level number,
133 * which is interpreted the same as the libusb_set_debug() parameter. When this
134 * environment variable is set, the message logging verbosity level is fixed
135 * and libusb_set_debug() effectively does nothing.
137 * libusbx can be compiled without any logging functions, useful for embedded
138 * systems. In this case, libusb_set_debug() and the LIBUSB_DEBUG environment
139 * variable have no effects.
141 * libusbx can also be compiled with verbose debugging messages. When the
142 * library is compiled in this way, all messages of all verbosities are always
143 * logged. libusb_set_debug() and the LIBUSB_DEBUG environment variable have
146 * \section remarks Other remarks
148 * libusbx does have imperfections. The \ref caveats "caveats" page attempts
153 * \page caveats Caveats
155 * \section devresets Device resets
157 * The libusb_reset_device() function allows you to reset a device. If your
158 * program has to call such a function, it should obviously be aware that
159 * the reset will cause device state to change (e.g. register values may be
162 * The problem is that any other program could reset the device your program
163 * is working with, at any time. libusbx does not offer a mechanism to inform
164 * you when this has happened, so if someone else resets your device it will
165 * not be clear to your own program why the device state has changed.
167 * Ultimately, this is a limitation of writing drivers in userspace.
168 * Separation from the USB stack in the underlying kernel makes it difficult
169 * for the operating system to deliver such notifications to your program.
170 * The Linux kernel USB stack allows such reset notifications to be delivered
171 * to in-kernel USB drivers, but it is not clear how such notifications could
172 * be delivered to second-class drivers that live in userspace.
174 * \section blockonly Blocking-only functionality
176 * The functionality listed below is only available through synchronous,
177 * blocking functions. There are no asynchronous/non-blocking alternatives,
178 * and no clear ways of implementing these.
180 * - Configuration activation (libusb_set_configuration())
181 * - Interface/alternate setting activation (libusb_set_interface_alt_setting())
182 * - Releasing of interfaces (libusb_release_interface())
183 * - Clearing of halt/stall condition (libusb_clear_halt())
184 * - Device resets (libusb_reset_device())
186 * \section nohotplug No hotplugging
188 * libusbx-1.0 lacks functionality for providing notifications of when devices
189 * are added or removed. This functionality is planned to be implemented
190 * in a later version of libusbx.
192 * That said, there is basic disconnection handling for open device handles:
193 * - If there are ongoing transfers, libusbx's handle_events loop will detect
194 * disconnections and complete ongoing transfers with the
195 * LIBUSB_TRANSFER_NO_DEVICE status code.
196 * - Many functions such as libusb_set_configuration() return the special
197 * LIBUSB_ERROR_NO_DEVICE error code when the device has been disconnected.
199 * \section configsel Configuration selection and handling
201 * When libusbx presents a device handle to an application, there is a chance
202 * that the corresponding device may be in unconfigured state. For devices
203 * with multiple configurations, there is also a chance that the configuration
204 * currently selected is not the one that the application wants to use.
206 * The obvious solution is to add a call to libusb_set_configuration() early
207 * on during your device initialization routines, but there are caveats to
209 * -# If the device is already in the desired configuration, calling
210 * libusb_set_configuration() using the same configuration value will cause
211 * a lightweight device reset. This may not be desirable behaviour.
212 * -# libusbx will be unable to change configuration if the device is in
213 * another configuration and other programs or drivers have claimed
214 * interfaces under that configuration.
215 * -# In the case where the desired configuration is already active, libusbx
216 * may not even be able to perform a lightweight device reset. For example,
217 * take my USB keyboard with fingerprint reader: I'm interested in driving
218 * the fingerprint reader interface through libusbx, but the kernel's
219 * USB-HID driver will almost always have claimed the keyboard interface.
220 * Because the kernel has claimed an interface, it is not even possible to
221 * perform the lightweight device reset, so libusb_set_configuration() will
222 * fail. (Luckily the device in question only has a single configuration.)
224 * One solution to some of the above problems is to consider the currently
225 * active configuration. If the configuration we want is already active, then
226 * we don't have to select any configuration:
228 cfg = libusb_get_configuration(dev);
230 libusb_set_configuration(dev, desired);
233 * This is probably suitable for most scenarios, but is inherently racy:
234 * another application or driver may change the selected configuration
235 * <em>after</em> the libusb_get_configuration() call.
237 * Even in cases where libusb_set_configuration() succeeds, consider that other
238 * applications or drivers may change configuration after your application
239 * calls libusb_set_configuration().
241 * One possible way to lock your device into a specific configuration is as
243 * -# Set the desired configuration (or use the logic above to realise that
244 * it is already in the desired configuration)
245 * -# Claim the interface that you wish to use
246 * -# Check that the currently active configuration is the one that you want
249 * The above method works because once an interface is claimed, no application
250 * or driver is able to select another configuration.
252 * \section earlycomp Early transfer completion
254 * NOTE: This section is currently Linux-centric. I am not sure if any of these
255 * considerations apply to Darwin or other platforms.
257 * When a transfer completes early (i.e. when less data is received/sent in
258 * any one packet than the transfer buffer allows for) then libusbx is designed
259 * to terminate the transfer immediately, not transferring or receiving any
260 * more data unless other transfers have been queued by the user.
262 * On legacy platforms, libusbx is unable to do this in all situations. After
263 * the incomplete packet occurs, "surplus" data may be transferred. For recent
264 * versions of libusbx, this information is kept (the data length of the
265 * transfer is updated) and, for device-to-host transfers, any surplus data was
266 * added to the buffer. Still, this is not a nice solution because it loses the
267 * information about the end of the short packet, and the user probably wanted
268 * that surplus data to arrive in the next logical transfer.
271 * \section zlp Zero length packets
273 * - libusbx is able to send a packet of zero length to an endpoint simply by
274 * submitting a transfer of zero length.
275 * - The \ref libusb_transfer_flags::LIBUSB_TRANSFER_ADD_ZERO_PACKET
276 * "LIBUSB_TRANSFER_ADD_ZERO_PACKET" flag is currently only supported on Linux.
280 * \page contexts Contexts
282 * It is possible that libusbx may be used simultaneously from two independent
283 * libraries linked into the same executable. For example, if your application
284 * has a plugin-like system which allows the user to dynamically load a range
285 * of modules into your program, it is feasible that two independently
286 * developed modules may both use libusbx.
288 * libusbx is written to allow for these multiple user scenarios. The two
289 * "instances" of libusbx will not interfere: libusb_set_debug() calls
290 * from one user will not affect the same settings for other users, other
291 * users can continue using libusbx after one of them calls libusb_exit(), etc.
293 * This is made possible through libusbx's <em>context</em> concept. When you
294 * call libusb_init(), you are (optionally) given a context. You can then pass
295 * this context pointer back into future libusbx functions.
297 * In order to keep things simple for more simplistic applications, it is
298 * legal to pass NULL to all functions requiring a context pointer (as long as
299 * you're sure no other code will attempt to use libusbx from the same process).
300 * When you pass NULL, the default context will be used. The default context
301 * is created the first time a process calls libusb_init() when no other
302 * context is alive. Contexts are destroyed during libusb_exit().
304 * The default context is reference-counted and can be shared. That means that
305 * if libusb_init(NULL) is called twice within the same process, the two
306 * users end up sharing the same context. The deinitialization and freeing of
307 * the default context will only happen when the last user calls libusb_exit().
308 * In other words, the default context is created and initialized when its
309 * reference count goes from 0 to 1, and is deinitialized and destroyed when
310 * its reference count goes from 1 to 0.
312 * You may be wondering why only a subset of libusbx functions require a
313 * context pointer in their function definition. Internally, libusbx stores
314 * context pointers in other objects (e.g. libusb_device instances) and hence
315 * can infer the context from those objects.
319 * @defgroup lib Library initialization/deinitialization
320 * This page details how to initialize and deinitialize libusbx. Initialization
321 * must be performed before using any libusbx functionality, and similarly you
322 * must not call any libusbx functions after deinitialization.
326 * @defgroup dev Device handling and enumeration
327 * The functionality documented below is designed to help with the following
329 * - Enumerating the USB devices currently attached to the system
330 * - Choosing a device to operate from your software
331 * - Opening and closing the chosen device
333 * \section nutshell In a nutshell...
335 * The description below really makes things sound more complicated than they
336 * actually are. The following sequence of function calls will be suitable
337 * for almost all scenarios and does not require you to have such a deep
338 * understanding of the resource management issues:
341 libusb_device **list;
342 libusb_device *found = NULL;
343 ssize_t cnt = libusb_get_device_list(NULL, &list);
349 for (i = 0; i < cnt; i++) {
350 libusb_device *device = list[i];
351 if (is_interesting(device)) {
358 libusb_device_handle *handle;
360 err = libusb_open(found, &handle);
366 libusb_free_device_list(list, 1);
369 * The two important points:
370 * - You asked libusb_free_device_list() to unreference the devices (2nd
372 * - You opened the device before freeing the list and unreferencing the
375 * If you ended up with a handle, you can now proceed to perform I/O on the
378 * \section devshandles Devices and device handles
379 * libusbx has a concept of a USB device, represented by the
380 * \ref libusb_device opaque type. A device represents a USB device that
381 * is currently or was previously connected to the system. Using a reference
382 * to a device, you can determine certain information about the device (e.g.
383 * you can read the descriptor data).
385 * The libusb_get_device_list() function can be used to obtain a list of
386 * devices currently connected to the system. This is known as device
389 * Just because you have a reference to a device does not mean it is
390 * necessarily usable. The device may have been unplugged, you may not have
391 * permission to operate such device, or another program or driver may be
394 * When you've found a device that you'd like to operate, you must ask
395 * libusbx to open the device using the libusb_open() function. Assuming
396 * success, libusbx then returns you a <em>device handle</em>
397 * (a \ref libusb_device_handle pointer). All "real" I/O operations then
398 * operate on the handle rather than the original device pointer.
400 * \section devref Device discovery and reference counting
402 * Device discovery (i.e. calling libusb_get_device_list()) returns a
403 * freshly-allocated list of devices. The list itself must be freed when
404 * you are done with it. libusbx also needs to know when it is OK to free
405 * the contents of the list - the devices themselves.
407 * To handle these issues, libusbx provides you with two separate items:
408 * - A function to free the list itself
409 * - A reference counting system for the devices inside
411 * New devices presented by the libusb_get_device_list() function all have a
412 * reference count of 1. You can increase and decrease reference count using
413 * libusb_ref_device() and libusb_unref_device(). A device is destroyed when
414 * its reference count reaches 0.
416 * With the above information in mind, the process of opening a device can
417 * be viewed as follows:
418 * -# Discover devices using libusb_get_device_list().
419 * -# Choose the device that you want to operate, and call libusb_open().
420 * -# Unref all devices in the discovered device list.
421 * -# Free the discovered device list.
423 * The order is important - you must not unreference the device before
424 * attempting to open it, because unreferencing it may destroy the device.
426 * For convenience, the libusb_free_device_list() function includes a
427 * parameter to optionally unreference all the devices in the list before
428 * freeing the list itself. This combines steps 3 and 4 above.
430 * As an implementation detail, libusb_open() actually adds a reference to
431 * the device in question. This is because the device remains available
432 * through the handle via libusb_get_device(). The reference is deleted during
436 /** @defgroup misc Miscellaneous */
438 /* we traverse usbfs without knowing how many devices we are going to find.
439 * so we create this discovered_devs model which is similar to a linked-list
440 * which grows when required. it can be freed once discovery has completed,
441 * eliminating the need for a list node in the libusb_device structure
443 #define DISCOVERED_DEVICES_SIZE_STEP 8
445 static struct discovered_devs *discovered_devs_alloc(void)
447 struct discovered_devs *ret =
448 malloc(sizeof(*ret) + (sizeof(void *) * DISCOVERED_DEVICES_SIZE_STEP));
452 ret->capacity = DISCOVERED_DEVICES_SIZE_STEP;
457 /* append a device to the discovered devices collection. may realloc itself,
458 * returning new discdevs. returns NULL on realloc failure. */
459 struct discovered_devs *discovered_devs_append(
460 struct discovered_devs *discdevs, struct libusb_device *dev)
462 size_t len = discdevs->len;
465 /* if there is space, just append the device */
466 if (len < discdevs->capacity) {
467 discdevs->devices[len] = libusb_ref_device(dev);
472 /* exceeded capacity, need to grow */
473 usbi_dbg("need to increase capacity");
474 capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
475 discdevs = realloc(discdevs,
476 sizeof(*discdevs) + (sizeof(void *) * capacity));
478 discdevs->capacity = capacity;
479 discdevs->devices[len] = libusb_ref_device(dev);
486 static void discovered_devs_free(struct discovered_devs *discdevs)
490 for (i = 0; i < discdevs->len; i++)
491 libusb_unref_device(discdevs->devices[i]);
496 /* Allocate a new device with a specific session ID. The returned device has
497 * a reference count of 1. */
498 struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
499 unsigned long session_id)
501 size_t priv_size = usbi_backend->device_priv_size;
502 struct libusb_device *dev = calloc(1, sizeof(*dev) + priv_size);
508 r = usbi_mutex_init(&dev->lock, NULL);
516 dev->session_data = session_id;
517 dev->speed = LIBUSB_SPEED_UNKNOWN;
518 memset(&dev->os_priv, 0, priv_size);
520 usbi_mutex_lock(&ctx->usb_devs_lock);
521 list_add(&dev->list, &ctx->usb_devs);
522 usbi_mutex_unlock(&ctx->usb_devs_lock);
526 /* Perform some final sanity checks on a newly discovered device. If this
527 * function fails (negative return code), the device should not be added
528 * to the discovered device list. */
529 int usbi_sanitize_device(struct libusb_device *dev)
532 unsigned char raw_desc[DEVICE_DESC_LENGTH];
533 uint8_t num_configurations;
536 r = usbi_backend->get_device_descriptor(dev, raw_desc, &host_endian);
540 num_configurations = raw_desc[DEVICE_DESC_LENGTH - 1];
541 if (num_configurations > USB_MAXCONFIG) {
542 usbi_err(DEVICE_CTX(dev), "too many configurations");
543 return LIBUSB_ERROR_IO;
544 } else if (0 == num_configurations)
545 usbi_dbg("zero configurations, maybe an unauthorized device");
547 dev->num_configurations = num_configurations;
551 /* Examine libusbx's internal list of known devices, looking for one with
552 * a specific session ID. Returns the matching device if it was found, and
554 struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
555 unsigned long session_id)
557 struct libusb_device *dev;
558 struct libusb_device *ret = NULL;
560 usbi_mutex_lock(&ctx->usb_devs_lock);
561 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device)
562 if (dev->session_data == session_id) {
566 usbi_mutex_unlock(&ctx->usb_devs_lock);
572 * Returns a list of USB devices currently attached to the system. This is
573 * your entry point into finding a USB device to operate.
575 * You are expected to unreference all the devices when you are done with
576 * them, and then free the list with libusb_free_device_list(). Note that
577 * libusb_free_device_list() can unref all the devices for you. Be careful
578 * not to unreference a device you are about to open until after you have
581 * This return value of this function indicates the number of devices in
582 * the resultant list. The list is actually one element larger, as it is
585 * \param ctx the context to operate on, or NULL for the default context
586 * \param list output location for a list of devices. Must be later freed with
587 * libusb_free_device_list().
588 * \returns the number of devices in the outputted list, or any
589 * \ref libusb_error according to errors encountered by the backend.
591 ssize_t API_EXPORTED libusb_get_device_list(libusb_context *ctx,
592 libusb_device ***list)
594 struct discovered_devs *discdevs = discovered_devs_alloc();
595 struct libusb_device **ret;
598 USBI_GET_CONTEXT(ctx);
602 return LIBUSB_ERROR_NO_MEM;
604 r = usbi_backend->get_device_list(ctx, &discdevs);
610 /* convert discovered_devs into a list */
612 ret = malloc(sizeof(void *) * (len + 1));
614 len = LIBUSB_ERROR_NO_MEM;
619 for (i = 0; i < len; i++) {
620 struct libusb_device *dev = discdevs->devices[i];
621 ret[i] = libusb_ref_device(dev);
626 discovered_devs_free(discdevs);
631 * Frees a list of devices previously discovered using
632 * libusb_get_device_list(). If the unref_devices parameter is set, the
633 * reference count of each device in the list is decremented by 1.
634 * \param list the list to free
635 * \param unref_devices whether to unref the devices in the list
637 void API_EXPORTED libusb_free_device_list(libusb_device **list,
645 struct libusb_device *dev;
647 while ((dev = list[i++]) != NULL)
648 libusb_unref_device(dev);
654 * Get the number of the bus that a device is connected to.
655 * \param dev a device
656 * \returns the bus number
658 uint8_t API_EXPORTED libusb_get_bus_number(libusb_device *dev)
660 return dev->bus_number;
664 * Get the number of the port that a device is connected to
665 * \param dev a device
666 * \returns the port number (0 if not available)
668 uint8_t API_EXPORTED libusb_get_port_number(libusb_device *dev)
670 return dev->port_number;
674 * Get the list of all port numbers from root for the specified device
675 * \param dev a device
676 * \param path the array that should contain the port numbers
677 * \param path_len the maximum length of the array. As per the USB 3.0
678 * specs, the current maximum limit for the depth is 7.
679 * \returns the number of elements filled
680 * \returns LIBUSB_ERROR_OVERFLOW if the array is too small
682 int API_EXPORTED libusb_get_port_path(libusb_context *ctx, libusb_device *dev, uint8_t* path, uint8_t path_len)
686 struct libusb_device **devs;
688 /* The device needs to be open, else the parents may have been destroyed */
689 r = libusb_get_device_list(ctx, &devs);
694 // HCDs can be listed as devices and would have port #0
695 // TODO: see how the other backends want to implement HCDs as parents
696 if (dev->port_number == 0)
700 return LIBUSB_ERROR_OVERFLOW;
702 path[i] = dev->port_number;
703 dev = dev->parent_dev;
705 libusb_free_device_list(devs, 1);
706 memmove(path, &path[i], path_len-i);
711 * Get the the parent from the specified device [EXPERIMENTAL]
712 * \param dev a device
713 * \returns the device parent or NULL if not available
714 * You should issue a libusb_get_device_list() before calling this
715 * function and make sure that you only access the parent before issuing
716 * libusb_free_device_list(). The reason is that libusbx currently does
717 * not maintain a permanent list of device instances, and therefore can
718 * only guarantee that parents are fully instantiated within a
719 * libusb_get_device_list() - libusb_free_device_list() block.
722 libusb_device * LIBUSB_CALL libusb_get_parent(libusb_device *dev)
724 return dev->parent_dev;
728 * Get the address of the device on the bus it is connected to.
729 * \param dev a device
730 * \returns the device address
732 uint8_t API_EXPORTED libusb_get_device_address(libusb_device *dev)
734 return dev->device_address;
738 * Get the negotiated connection speed for a device.
739 * \param dev a device
740 * \returns a \ref libusb_speed code, where LIBUSB_SPEED_UNKNOWN means that
741 * the OS doesn't know or doesn't support returning the negotiated speed.
743 int API_EXPORTED libusb_get_device_speed(libusb_device *dev)
748 static const struct libusb_endpoint_descriptor *find_endpoint(
749 struct libusb_config_descriptor *config, unsigned char endpoint)
752 for (iface_idx = 0; iface_idx < config->bNumInterfaces; iface_idx++) {
753 const struct libusb_interface *iface = &config->interface[iface_idx];
756 for (altsetting_idx = 0; altsetting_idx < iface->num_altsetting;
758 const struct libusb_interface_descriptor *altsetting
759 = &iface->altsetting[altsetting_idx];
762 for (ep_idx = 0; ep_idx < altsetting->bNumEndpoints; ep_idx++) {
763 const struct libusb_endpoint_descriptor *ep =
764 &altsetting->endpoint[ep_idx];
765 if (ep->bEndpointAddress == endpoint)
774 * Convenience function to retrieve the wMaxPacketSize value for a particular
775 * endpoint in the active device configuration.
777 * This function was originally intended to be of assistance when setting up
778 * isochronous transfers, but a design mistake resulted in this function
779 * instead. It simply returns the wMaxPacketSize value without considering
780 * its contents. If you're dealing with isochronous transfers, you probably
781 * want libusb_get_max_iso_packet_size() instead.
783 * \param dev a device
784 * \param endpoint address of the endpoint in question
785 * \returns the wMaxPacketSize value
786 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
787 * \returns LIBUSB_ERROR_OTHER on other failure
789 int API_EXPORTED libusb_get_max_packet_size(libusb_device *dev,
790 unsigned char endpoint)
792 struct libusb_config_descriptor *config;
793 const struct libusb_endpoint_descriptor *ep;
796 r = libusb_get_active_config_descriptor(dev, &config);
798 usbi_err(DEVICE_CTX(dev),
799 "could not retrieve active config descriptor");
800 return LIBUSB_ERROR_OTHER;
803 ep = find_endpoint(config, endpoint);
805 return LIBUSB_ERROR_NOT_FOUND;
807 r = ep->wMaxPacketSize;
808 libusb_free_config_descriptor(config);
813 * Calculate the maximum packet size which a specific endpoint is capable is
814 * sending or receiving in the duration of 1 microframe
816 * Only the active configution is examined. The calculation is based on the
817 * wMaxPacketSize field in the endpoint descriptor as described in section
818 * 9.6.6 in the USB 2.0 specifications.
820 * If acting on an isochronous or interrupt endpoint, this function will
821 * multiply the value found in bits 0:10 by the number of transactions per
822 * microframe (determined by bits 11:12). Otherwise, this function just
823 * returns the numeric value found in bits 0:10.
825 * This function is useful for setting up isochronous transfers, for example
826 * you might pass the return value from this function to
827 * libusb_set_iso_packet_lengths() in order to set the length field of every
828 * isochronous packet in a transfer.
832 * \param dev a device
833 * \param endpoint address of the endpoint in question
834 * \returns the maximum packet size which can be sent/received on this endpoint
835 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
836 * \returns LIBUSB_ERROR_OTHER on other failure
838 int API_EXPORTED libusb_get_max_iso_packet_size(libusb_device *dev,
839 unsigned char endpoint)
841 struct libusb_config_descriptor *config;
842 const struct libusb_endpoint_descriptor *ep;
843 enum libusb_transfer_type ep_type;
847 r = libusb_get_active_config_descriptor(dev, &config);
849 usbi_err(DEVICE_CTX(dev),
850 "could not retrieve active config descriptor");
851 return LIBUSB_ERROR_OTHER;
854 ep = find_endpoint(config, endpoint);
856 return LIBUSB_ERROR_NOT_FOUND;
858 val = ep->wMaxPacketSize;
859 ep_type = ep->bmAttributes & 0x3;
860 libusb_free_config_descriptor(config);
863 if (ep_type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
864 || ep_type == LIBUSB_TRANSFER_TYPE_INTERRUPT)
865 r *= (1 + ((val >> 11) & 3));
870 * Increment the reference count of a device.
871 * \param dev the device to reference
872 * \returns the same device
875 libusb_device * LIBUSB_CALL libusb_ref_device(libusb_device *dev)
877 usbi_mutex_lock(&dev->lock);
879 usbi_mutex_unlock(&dev->lock);
884 * Decrement the reference count of a device. If the decrement operation
885 * causes the reference count to reach zero, the device shall be destroyed.
886 * \param dev the device to unreference
888 void API_EXPORTED libusb_unref_device(libusb_device *dev)
895 usbi_mutex_lock(&dev->lock);
896 refcnt = --dev->refcnt;
897 usbi_mutex_unlock(&dev->lock);
900 usbi_dbg("destroy device %d.%d", dev->bus_number, dev->device_address);
902 if (usbi_backend->destroy_device)
903 usbi_backend->destroy_device(dev);
905 usbi_mutex_lock(&dev->ctx->usb_devs_lock);
906 list_del(&dev->list);
907 usbi_mutex_unlock(&dev->ctx->usb_devs_lock);
909 usbi_mutex_destroy(&dev->lock);
915 * Interrupt the iteration of the event handling thread, so that it picks
918 void usbi_fd_notification(struct libusb_context *ctx)
920 unsigned char dummy = 1;
926 /* record that we are messing with poll fds */
927 usbi_mutex_lock(&ctx->pollfd_modify_lock);
928 ctx->pollfd_modify++;
929 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
931 /* write some data on control pipe to interrupt event handlers */
932 r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
934 usbi_warn(ctx, "internal signalling write failed");
935 usbi_mutex_lock(&ctx->pollfd_modify_lock);
936 ctx->pollfd_modify--;
937 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
941 /* take event handling lock */
942 libusb_lock_events(ctx);
944 /* read the dummy data */
945 r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
947 usbi_warn(ctx, "internal signalling read failed");
949 /* we're done with modifying poll fds */
950 usbi_mutex_lock(&ctx->pollfd_modify_lock);
951 ctx->pollfd_modify--;
952 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
954 /* Release event handling lock and wake up event waiters */
955 libusb_unlock_events(ctx);
959 * Open a device and obtain a device handle. A handle allows you to perform
960 * I/O on the device in question.
962 * Internally, this function adds a reference to the device and makes it
963 * available to you through libusb_get_device(). This reference is removed
964 * during libusb_close().
966 * This is a non-blocking function; no requests are sent over the bus.
968 * \param dev the device to open
969 * \param handle output location for the returned device handle pointer. Only
970 * populated when the return code is 0.
971 * \returns 0 on success
972 * \returns LIBUSB_ERROR_NO_MEM on memory allocation failure
973 * \returns LIBUSB_ERROR_ACCESS if the user has insufficient permissions
974 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
975 * \returns another LIBUSB_ERROR code on other failure
977 int API_EXPORTED libusb_open(libusb_device *dev,
978 libusb_device_handle **handle)
980 struct libusb_context *ctx = DEVICE_CTX(dev);
981 struct libusb_device_handle *_handle;
982 size_t priv_size = usbi_backend->device_handle_priv_size;
984 usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);
986 _handle = malloc(sizeof(*_handle) + priv_size);
988 return LIBUSB_ERROR_NO_MEM;
990 r = usbi_mutex_init(&_handle->lock, NULL);
993 return LIBUSB_ERROR_OTHER;
996 _handle->dev = libusb_ref_device(dev);
997 _handle->claimed_interfaces = 0;
998 memset(&_handle->os_priv, 0, priv_size);
1000 r = usbi_backend->open(_handle);
1002 usbi_dbg("open %d.%d returns %d", dev->bus_number, dev->device_address, r);
1003 libusb_unref_device(dev);
1004 usbi_mutex_destroy(&_handle->lock);
1009 usbi_mutex_lock(&ctx->open_devs_lock);
1010 list_add(&_handle->list, &ctx->open_devs);
1011 usbi_mutex_unlock(&ctx->open_devs_lock);
1014 /* At this point, we want to interrupt any existing event handlers so
1015 * that they realise the addition of the new device's poll fd. One
1016 * example when this is desirable is if the user is running a separate
1017 * dedicated libusbx events handling thread, which is running with a long
1018 * or infinite timeout. We want to interrupt that iteration of the loop,
1019 * so that it picks up the new fd, and then continues. */
1020 usbi_fd_notification(ctx);
1026 * Convenience function for finding a device with a particular
1027 * <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
1028 * for those scenarios where you are using libusbx to knock up a quick test
1029 * application - it allows you to avoid calling libusb_get_device_list() and
1030 * worrying about traversing/freeing the list.
1032 * This function has limitations and is hence not intended for use in real
1033 * applications: if multiple devices have the same IDs it will only
1034 * give you the first one, etc.
1036 * \param ctx the context to operate on, or NULL for the default context
1037 * \param vendor_id the idVendor value to search for
1038 * \param product_id the idProduct value to search for
1039 * \returns a handle for the first found device, or NULL on error or if the
1040 * device could not be found. */
1042 libusb_device_handle * LIBUSB_CALL libusb_open_device_with_vid_pid(
1043 libusb_context *ctx, uint16_t vendor_id, uint16_t product_id)
1045 struct libusb_device **devs;
1046 struct libusb_device *found = NULL;
1047 struct libusb_device *dev;
1048 struct libusb_device_handle *handle = NULL;
1052 if (libusb_get_device_list(ctx, &devs) < 0)
1055 while ((dev = devs[i++]) != NULL) {
1056 struct libusb_device_descriptor desc;
1057 r = libusb_get_device_descriptor(dev, &desc);
1060 if (desc.idVendor == vendor_id && desc.idProduct == product_id) {
1067 r = libusb_open(found, &handle);
1073 libusb_free_device_list(devs, 1);
1077 static void do_close(struct libusb_context *ctx,
1078 struct libusb_device_handle *dev_handle)
1080 struct usbi_transfer *itransfer;
1081 struct usbi_transfer *tmp;
1083 libusb_lock_events(ctx);
1085 /* remove any transfers in flight that are for this device */
1086 usbi_mutex_lock(&ctx->flying_transfers_lock);
1088 /* safe iteration because transfers may be being deleted */
1089 list_for_each_entry_safe(itransfer, tmp, &ctx->flying_transfers, list, struct usbi_transfer) {
1090 struct libusb_transfer *transfer =
1091 USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
1093 if (transfer->dev_handle != dev_handle)
1096 if (!(itransfer->flags & USBI_TRANSFER_DEVICE_DISAPPEARED)) {
1097 usbi_err(ctx, "Device handle closed while transfer was still being processed, but the device is still connected as far as we know");
1099 if (itransfer->flags & USBI_TRANSFER_CANCELLING)
1100 usbi_warn(ctx, "A cancellation for an in-flight transfer hasn't completed but closing the device handle");
1102 usbi_err(ctx, "A cancellation hasn't even been scheduled on the transfer for which the device is closing");
1105 /* remove from the list of in-flight transfers and make sure
1106 * we don't accidentally use the device handle in the future
1107 * (or that such accesses will be easily caught and identified as a crash)
1109 usbi_mutex_lock(&itransfer->lock);
1110 list_del(&itransfer->list);
1111 transfer->dev_handle = NULL;
1112 usbi_mutex_unlock(&itransfer->lock);
1114 /* it is up to the user to free up the actual transfer struct. this is
1115 * just making sure that we don't attempt to process the transfer after
1116 * the device handle is invalid
1118 usbi_dbg("Removed transfer %p from the in-flight list because device handle %p closed",
1119 transfer, dev_handle);
1121 usbi_mutex_unlock(&ctx->flying_transfers_lock);
1123 libusb_unlock_events(ctx);
1125 usbi_mutex_lock(&ctx->open_devs_lock);
1126 list_del(&dev_handle->list);
1127 usbi_mutex_unlock(&ctx->open_devs_lock);
1129 usbi_backend->close(dev_handle);
1130 libusb_unref_device(dev_handle->dev);
1131 usbi_mutex_destroy(&dev_handle->lock);
1136 * Close a device handle. Should be called on all open handles before your
1137 * application exits.
1139 * Internally, this function destroys the reference that was added by
1140 * libusb_open() on the given device.
1142 * This is a non-blocking function; no requests are sent over the bus.
1144 * \param dev_handle the handle to close
1146 void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
1148 struct libusb_context *ctx;
1149 unsigned char dummy = 1;
1156 ctx = HANDLE_CTX(dev_handle);
1158 /* Similarly to libusb_open(), we want to interrupt all event handlers
1159 * at this point. More importantly, we want to perform the actual close of
1160 * the device while holding the event handling lock (preventing any other
1161 * thread from doing event handling) because we will be removing a file
1162 * descriptor from the polling loop. */
1164 /* record that we are messing with poll fds */
1165 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1166 ctx->pollfd_modify++;
1167 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1169 /* write some data on control pipe to interrupt event handlers */
1170 r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
1172 usbi_warn(ctx, "internal signalling write failed, closing anyway");
1173 do_close(ctx, dev_handle);
1174 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1175 ctx->pollfd_modify--;
1176 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1180 /* take event handling lock */
1181 libusb_lock_events(ctx);
1183 /* read the dummy data */
1184 r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
1186 usbi_warn(ctx, "internal signalling read failed, closing anyway");
1188 /* Close the device */
1189 do_close(ctx, dev_handle);
1191 /* we're done with modifying poll fds */
1192 usbi_mutex_lock(&ctx->pollfd_modify_lock);
1193 ctx->pollfd_modify--;
1194 usbi_mutex_unlock(&ctx->pollfd_modify_lock);
1196 /* Release event handling lock and wake up event waiters */
1197 libusb_unlock_events(ctx);
1201 * Get the underlying device for a handle. This function does not modify
1202 * the reference count of the returned device, so do not feel compelled to
1203 * unreference it when you are done.
1204 * \param dev_handle a device handle
1205 * \returns the underlying device
1208 libusb_device * LIBUSB_CALL libusb_get_device(libusb_device_handle *dev_handle)
1210 return dev_handle->dev;
1214 * Determine the bConfigurationValue of the currently active configuration.
1216 * You could formulate your own control request to obtain this information,
1217 * but this function has the advantage that it may be able to retrieve the
1218 * information from operating system caches (no I/O involved).
1220 * If the OS does not cache this information, then this function will block
1221 * while a control transfer is submitted to retrieve the information.
1223 * This function will return a value of 0 in the <tt>config</tt> output
1224 * parameter if the device is in unconfigured state.
1226 * \param dev a device handle
1227 * \param config output location for the bConfigurationValue of the active
1228 * configuration (only valid for return code 0)
1229 * \returns 0 on success
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_get_configuration(libusb_device_handle *dev,
1236 int r = LIBUSB_ERROR_NOT_SUPPORTED;
1239 if (usbi_backend->get_configuration)
1240 r = usbi_backend->get_configuration(dev, config);
1242 if (r == LIBUSB_ERROR_NOT_SUPPORTED) {
1244 usbi_dbg("falling back to control message");
1245 r = libusb_control_transfer(dev, LIBUSB_ENDPOINT_IN,
1246 LIBUSB_REQUEST_GET_CONFIGURATION, 0, 0, &tmp, 1, 1000);
1248 usbi_err(HANDLE_CTX(dev), "zero bytes returned in ctrl transfer?");
1249 r = LIBUSB_ERROR_IO;
1250 } else if (r == 1) {
1254 usbi_dbg("control failed, error %d", r);
1259 usbi_dbg("active config %d", *config);
1265 * Set the active configuration for a device.
1267 * The operating system may or may not have already set an active
1268 * configuration on the device. It is up to your application to ensure the
1269 * correct configuration is selected before you attempt to claim interfaces
1270 * and perform other operations.
1272 * If you call this function on a device already configured with the selected
1273 * configuration, then this function will act as a lightweight device reset:
1274 * it will issue a SET_CONFIGURATION request using the current configuration,
1275 * causing most USB-related device state to be reset (altsetting reset to zero,
1276 * endpoint halts cleared, toggles reset).
1278 * You cannot change/reset configuration if your application has claimed
1279 * interfaces - you should free them with libusb_release_interface() first.
1280 * You cannot change/reset configuration if other applications or drivers have
1281 * claimed interfaces.
1283 * A configuration value of -1 will put the device in unconfigured state.
1284 * The USB specifications state that a configuration value of 0 does this,
1285 * however buggy devices exist which actually have a configuration 0.
1287 * You should always use this function rather than formulating your own
1288 * SET_CONFIGURATION control request. This is because the underlying operating
1289 * system needs to know when such changes happen.
1291 * This is a blocking function.
1293 * \param dev a device handle
1294 * \param configuration the bConfigurationValue of the configuration you
1295 * wish to activate, or -1 if you wish to put the device in unconfigured state
1296 * \returns 0 on success
1297 * \returns LIBUSB_ERROR_NOT_FOUND if the requested configuration does not exist
1298 * \returns LIBUSB_ERROR_BUSY if interfaces are currently claimed
1299 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1300 * \returns another LIBUSB_ERROR code on other failure
1302 int API_EXPORTED libusb_set_configuration(libusb_device_handle *dev,
1305 usbi_dbg("configuration %d", configuration);
1306 return usbi_backend->set_configuration(dev, configuration);
1310 * Claim an interface on a given device handle. You must claim the interface
1311 * you wish to use before you can perform I/O on any of its endpoints.
1313 * It is legal to attempt to claim an already-claimed interface, in which
1314 * case libusbx just returns 0 without doing anything.
1316 * Claiming of interfaces is a purely logical operation; it does not cause
1317 * any requests to be sent over the bus. Interface claiming is used to
1318 * instruct the underlying operating system that your application wishes
1319 * to take ownership of the interface.
1321 * This is a non-blocking function.
1323 * \param dev a device handle
1324 * \param interface_number the <tt>bInterfaceNumber</tt> of the interface you
1326 * \returns 0 on success
1327 * \returns LIBUSB_ERROR_NOT_FOUND if the requested interface does not exist
1328 * \returns LIBUSB_ERROR_BUSY if another program or driver has claimed the
1330 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1331 * \returns a LIBUSB_ERROR code on other failure
1333 int API_EXPORTED libusb_claim_interface(libusb_device_handle *dev,
1334 int interface_number)
1338 usbi_dbg("interface %d", interface_number);
1339 if (interface_number >= USB_MAXINTERFACES)
1340 return LIBUSB_ERROR_INVALID_PARAM;
1342 usbi_mutex_lock(&dev->lock);
1343 if (dev->claimed_interfaces & (1 << interface_number))
1346 r = usbi_backend->claim_interface(dev, interface_number);
1348 dev->claimed_interfaces |= 1 << interface_number;
1351 usbi_mutex_unlock(&dev->lock);
1356 * Release an interface previously claimed with libusb_claim_interface(). You
1357 * should release all claimed interfaces before closing a device handle.
1359 * This is a blocking function. A SET_INTERFACE control request will be sent
1360 * to the device, resetting interface state to the first alternate setting.
1362 * \param dev a device handle
1363 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1364 * previously-claimed interface
1365 * \returns 0 on success
1366 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed
1367 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1368 * \returns another LIBUSB_ERROR code on other failure
1370 int API_EXPORTED libusb_release_interface(libusb_device_handle *dev,
1371 int interface_number)
1375 usbi_dbg("interface %d", interface_number);
1376 if (interface_number >= USB_MAXINTERFACES)
1377 return LIBUSB_ERROR_INVALID_PARAM;
1379 usbi_mutex_lock(&dev->lock);
1380 if (!(dev->claimed_interfaces & (1 << interface_number))) {
1381 r = LIBUSB_ERROR_NOT_FOUND;
1385 r = usbi_backend->release_interface(dev, interface_number);
1387 dev->claimed_interfaces &= ~(1 << interface_number);
1390 usbi_mutex_unlock(&dev->lock);
1395 * Activate an alternate setting for an interface. The interface must have
1396 * been previously claimed with libusb_claim_interface().
1398 * You should always use this function rather than formulating your own
1399 * SET_INTERFACE control request. This is because the underlying operating
1400 * system needs to know when such changes happen.
1402 * This is a blocking function.
1404 * \param dev a device handle
1405 * \param interface_number the <tt>bInterfaceNumber</tt> of the
1406 * previously-claimed interface
1407 * \param alternate_setting the <tt>bAlternateSetting</tt> of the alternate
1408 * setting to activate
1409 * \returns 0 on success
1410 * \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed, or the
1411 * requested alternate setting does not exist
1412 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1413 * \returns another LIBUSB_ERROR code on other failure
1415 int API_EXPORTED libusb_set_interface_alt_setting(libusb_device_handle *dev,
1416 int interface_number, int alternate_setting)
1418 usbi_dbg("interface %d altsetting %d",
1419 interface_number, alternate_setting);
1420 if (interface_number >= USB_MAXINTERFACES)
1421 return LIBUSB_ERROR_INVALID_PARAM;
1423 usbi_mutex_lock(&dev->lock);
1424 if (!(dev->claimed_interfaces & (1 << interface_number))) {
1425 usbi_mutex_unlock(&dev->lock);
1426 return LIBUSB_ERROR_NOT_FOUND;
1428 usbi_mutex_unlock(&dev->lock);
1430 return usbi_backend->set_interface_altsetting(dev, interface_number,
1435 * Clear the halt/stall condition for an endpoint. Endpoints with halt status
1436 * are unable to receive or transmit data until the halt condition is stalled.
1438 * You should cancel all pending transfers before attempting to clear the halt
1441 * This is a blocking function.
1443 * \param dev a device handle
1444 * \param endpoint the endpoint to clear halt status
1445 * \returns 0 on success
1446 * \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
1447 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1448 * \returns another LIBUSB_ERROR code on other failure
1450 int API_EXPORTED libusb_clear_halt(libusb_device_handle *dev,
1451 unsigned char endpoint)
1453 usbi_dbg("endpoint %x", endpoint);
1454 return usbi_backend->clear_halt(dev, endpoint);
1458 * Perform a USB port reset to reinitialize a device. The system will attempt
1459 * to restore the previous configuration and alternate settings after the
1460 * reset has completed.
1462 * If the reset fails, the descriptors change, or the previous state cannot be
1463 * restored, the device will appear to be disconnected and reconnected. This
1464 * means that the device handle is no longer valid (you should close it) and
1465 * rediscover the device. A return code of LIBUSB_ERROR_NOT_FOUND indicates
1466 * when this is the case.
1468 * This is a blocking function which usually incurs a noticeable delay.
1470 * \param dev a handle of the device to reset
1471 * \returns 0 on success
1472 * \returns LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the
1473 * device has been disconnected
1474 * \returns another LIBUSB_ERROR code on other failure
1476 int API_EXPORTED libusb_reset_device(libusb_device_handle *dev)
1479 return usbi_backend->reset_device(dev);
1483 * Determine if a kernel driver is active on an interface. If a kernel driver
1484 * is active, you cannot claim the interface, and libusbx will be unable to
1487 * This functionality is not available on Windows.
1489 * \param dev a device handle
1490 * \param interface_number the interface to check
1491 * \returns 0 if no kernel driver is active
1492 * \returns 1 if a kernel driver is active
1493 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1494 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1496 * \returns another LIBUSB_ERROR code on other failure
1497 * \see libusb_detach_kernel_driver()
1499 int API_EXPORTED libusb_kernel_driver_active(libusb_device_handle *dev,
1500 int interface_number)
1502 usbi_dbg("interface %d", interface_number);
1503 if (usbi_backend->kernel_driver_active)
1504 return usbi_backend->kernel_driver_active(dev, interface_number);
1506 return LIBUSB_ERROR_NOT_SUPPORTED;
1510 * Detach a kernel driver from an interface. If successful, you will then be
1511 * able to claim the interface and perform I/O.
1513 * This functionality is not available on Darwin or Windows.
1515 * \param dev a device handle
1516 * \param interface_number the interface to detach the driver from
1517 * \returns 0 on success
1518 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1519 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1520 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1521 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1523 * \returns another LIBUSB_ERROR code on other failure
1524 * \see libusb_kernel_driver_active()
1526 int API_EXPORTED libusb_detach_kernel_driver(libusb_device_handle *dev,
1527 int interface_number)
1529 usbi_dbg("interface %d", interface_number);
1530 if (usbi_backend->detach_kernel_driver)
1531 return usbi_backend->detach_kernel_driver(dev, interface_number);
1533 return LIBUSB_ERROR_NOT_SUPPORTED;
1537 * Re-attach an interface's kernel driver, which was previously detached
1538 * using libusb_detach_kernel_driver(). This call is only effective on
1539 * Linux and returns LIBUSB_ERROR_NOT_SUPPORTED on all other platforms.
1541 * This functionality is not available on Darwin or Windows.
1543 * \param dev a device handle
1544 * \param interface_number the interface to attach the driver from
1545 * \returns 0 on success
1546 * \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
1547 * \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
1548 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
1549 * \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
1551 * \returns LIBUSB_ERROR_BUSY if the driver cannot be attached because the
1552 * interface is claimed by a program or driver
1553 * \returns another LIBUSB_ERROR code on other failure
1554 * \see libusb_kernel_driver_active()
1556 int API_EXPORTED libusb_attach_kernel_driver(libusb_device_handle *dev,
1557 int interface_number)
1559 usbi_dbg("interface %d", interface_number);
1560 if (usbi_backend->attach_kernel_driver)
1561 return usbi_backend->attach_kernel_driver(dev, interface_number);
1563 return LIBUSB_ERROR_NOT_SUPPORTED;
1567 * Set log message verbosity.
1569 * The default level is \ref LOG_LEVEL_NONE, which means no messages are ever
1570 * printed. If you choose to increase the message verbosity level, ensure
1571 * that your application does not close the stdout/stderr file descriptors.
1573 * You are advised to use level \ref LOG_LEVEL_WARNING. libusbx is conservative
1574 * with its message logging and most of the time, will only log messages that
1575 * explain error conditions and other oddities. This will help you debug
1578 * If the LIBUSB_DEBUG environment variable was set when libusbx was
1579 * initialized, this function does nothing: the message verbosity is fixed
1580 * to the value in the environment variable.
1582 * If libusbx was compiled without any message logging, this function does
1583 * nothing: you'll never get any messages.
1585 * If libusbx was compiled with verbose debug message logging, this function
1586 * does nothing: you'll always get messages from all levels.
1588 * \param ctx the context to operate on, or NULL for the default context
1589 * \param level debug level to set
1591 void API_EXPORTED libusb_set_debug(libusb_context *ctx, int level)
1593 USBI_GET_CONTEXT(ctx);
1594 if (!ctx->debug_fixed)
1599 * Initialize libusb. This function must be called before calling any other
1602 * If you do not provide an output location for a context pointer, a default
1603 * context will be created. If there was already a default context, it will
1604 * be reused (and nothing will be initialized/reinitialized).
1606 * \param context Optional output location for context pointer.
1607 * Only valid on return code 0.
1608 * \returns 0 on success, or a LIBUSB_ERROR code on failure
1611 int API_EXPORTED libusb_init(libusb_context **context)
1613 char *dbg = getenv("LIBUSB_DEBUG");
1614 struct libusb_context *ctx;
1617 usbi_mutex_static_lock(&default_context_lock);
1619 if (!timestamp_origin.tv_sec) {
1620 usbi_gettimeofday(×tamp_origin, NULL);
1623 if (!context && usbi_default_context) {
1624 usbi_dbg("reusing default context");
1625 default_context_refcnt++;
1626 usbi_mutex_static_unlock(&default_context_lock);
1630 ctx = malloc(sizeof(*ctx));
1632 r = LIBUSB_ERROR_NO_MEM;
1635 memset(ctx, 0, sizeof(*ctx));
1637 #ifdef ENABLE_DEBUG_LOGGING
1638 ctx->debug = LOG_LEVEL_DEBUG;
1642 ctx->debug = atoi(dbg);
1644 ctx->debug_fixed = 1;
1647 /* default context should be initialized before calling usbi_dbg */
1648 if (!usbi_default_context) {
1649 usbi_default_context = ctx;
1650 usbi_dbg("created default context");
1653 usbi_dbg("libusbx v%d.%d.%d.%d", libusb_version_internal.major, libusb_version_internal.minor,
1654 libusb_version_internal.micro, libusb_version_internal.nano);
1656 if (usbi_backend->init) {
1657 r = usbi_backend->init(ctx);
1662 usbi_mutex_init(&ctx->usb_devs_lock, NULL);
1663 usbi_mutex_init(&ctx->open_devs_lock, NULL);
1664 list_init(&ctx->usb_devs);
1665 list_init(&ctx->open_devs);
1667 r = usbi_io_init(ctx);
1669 if (usbi_backend->exit)
1670 usbi_backend->exit();
1671 goto err_destroy_mutex;
1676 } else if (!usbi_default_context) {
1677 usbi_dbg("created default context");
1678 usbi_default_context = ctx;
1679 default_context_refcnt++;
1681 usbi_mutex_static_unlock(&default_context_lock);
1686 usbi_mutex_destroy(&ctx->open_devs_lock);
1687 usbi_mutex_destroy(&ctx->usb_devs_lock);
1691 usbi_mutex_static_unlock(&default_context_lock);
1696 * Deinitialize libusb. Should be called after closing all open devices and
1697 * before your application terminates.
1698 * \param ctx the context to deinitialize, or NULL for the default context
1700 void API_EXPORTED libusb_exit(struct libusb_context *ctx)
1703 USBI_GET_CONTEXT(ctx);
1705 /* if working with default context, only actually do the deinitialization
1706 * if we're the last user */
1707 if (ctx == usbi_default_context) {
1708 usbi_mutex_static_lock(&default_context_lock);
1709 if (--default_context_refcnt > 0) {
1710 usbi_dbg("not destroying default context");
1711 usbi_mutex_static_unlock(&default_context_lock);
1714 usbi_dbg("destroying default context");
1715 usbi_default_context = NULL;
1716 usbi_mutex_static_unlock(&default_context_lock);
1719 /* a little sanity check. doesn't bother with open_devs locking because
1720 * unless there is an application bug, nobody will be accessing this. */
1721 if (!list_empty(&ctx->open_devs))
1722 usbi_warn(ctx, "application left some devices open");
1725 if (usbi_backend->exit)
1726 usbi_backend->exit();
1728 usbi_mutex_destroy(&ctx->open_devs_lock);
1729 usbi_mutex_destroy(&ctx->usb_devs_lock);
1734 * Check at runtime if the loaded library has a given capability.
1736 * \param capability the \ref libusb_capability to check for
1737 * \returns 1 if the running library has the capability, 0 otherwise
1739 int API_EXPORTED libusb_has_capability(uint32_t capability)
1741 enum libusb_capability cap = capability;
1743 case LIBUSB_CAP_HAS_CAPABILITY:
1749 /* this is defined in libusbi.h if needed */
1750 #ifdef LIBUSB_GETTIMEOFDAY_WIN32
1753 * Implementation according to:
1754 * The Open Group Base Specifications Issue 6
1755 * IEEE Std 1003.1, 2004 Edition
1759 * THIS SOFTWARE IS NOT COPYRIGHTED
1761 * This source code is offered for use in the public domain. You may
1762 * use, modify or distribute it freely.
1764 * This code is distributed in the hope that it will be useful but
1765 * WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
1766 * DISCLAIMED. This includes but is not limited to warranties of
1767 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
1770 * Danny Smith <dannysmith@users.sourceforge.net>
1773 /* Offset between 1/1/1601 and 1/1/1970 in 100 nanosec units */
1774 #define _W32_FT_OFFSET (116444736000000000)
1776 int usbi_gettimeofday(struct timeval *tp, void *tzp)
1779 unsigned __int64 ns100; /*time since 1 Jan 1601 in 100ns units */
1785 GetSystemTimeAsFileTime (&_now.ft);
1786 tp->tv_usec=(long)((_now.ns100 / 10) % 1000000 );
1787 tp->tv_sec= (long)((_now.ns100 - _W32_FT_OFFSET) / 10000000);
1789 /* Always return 0 as per Open Group Base Specifications Issue 6.
1790 Do not set errno on error. */
1795 void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
1796 const char *function, const char *format, va_list args)
1798 const char *prefix = "";
1801 static int has_debug_header_been_displayed = 0;
1803 #ifdef ENABLE_DEBUG_LOGGING
1806 USBI_GET_CONTEXT(ctx);
1809 global_debug = (ctx->debug == LOG_LEVEL_DEBUG);
1812 if (level == LOG_LEVEL_WARNING && ctx->debug < LOG_LEVEL_WARNING)
1814 if (level == LOG_LEVEL_INFO && ctx->debug < LOG_LEVEL_INFO)
1816 if (level == LOG_LEVEL_DEBUG && ctx->debug < LOG_LEVEL_DEBUG)
1820 usbi_gettimeofday(&now, NULL);
1821 if ((global_debug) && (!has_debug_header_been_displayed)) {
1822 has_debug_header_been_displayed = 1;
1823 fprintf(stderr, "[timestamp] [threadID] facility level [function call] <message>\n");
1824 fprintf(stderr, "--------------------------------------------------------------------------------\n");
1826 if (now.tv_usec < timestamp_origin.tv_usec) {
1828 now.tv_usec += 1000000;
1830 now.tv_sec -= timestamp_origin.tv_sec;
1831 now.tv_usec -= timestamp_origin.tv_usec;
1834 case LOG_LEVEL_INFO:
1837 case LOG_LEVEL_WARNING:
1840 case LOG_LEVEL_ERROR:
1843 case LOG_LEVEL_DEBUG:
1846 case LOG_LEVEL_NONE:
1854 fprintf(stderr, "[%2d.%06d] [%08x] libusbx: %s [%s] ",
1855 (int)now.tv_sec, (int)now.tv_usec, usbi_get_tid(), prefix, function);
1857 fprintf(stderr, "libusbx: %s [%s] ", prefix, function);
1860 vfprintf(stderr, format, args);
1862 fprintf(stderr, "\n");
1865 void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
1866 const char *function, const char *format, ...)
1870 va_start (args, format);
1871 usbi_log_v(ctx, level, function, format, args);
1876 * Returns a constant NULL-terminated string with the ASCII name of a libusb
1877 * error code. The caller must not free() the returned string.
1879 * \param error_code The \ref libusb_error code to return the name of.
1880 * \returns The error name, or the string **UNKNOWN** if the value of
1881 * error_code is not a known error code.
1883 DEFAULT_VISIBILITY const char * LIBUSB_CALL libusb_error_name(int error_code)
1885 enum libusb_error error = error_code;
1887 case LIBUSB_SUCCESS:
1888 return "LIBUSB_SUCCESS";
1889 case LIBUSB_ERROR_IO:
1890 return "LIBUSB_ERROR_IO";
1891 case LIBUSB_ERROR_INVALID_PARAM:
1892 return "LIBUSB_ERROR_INVALID_PARAM";
1893 case LIBUSB_ERROR_ACCESS:
1894 return "LIBUSB_ERROR_ACCESS";
1895 case LIBUSB_ERROR_NO_DEVICE:
1896 return "LIBUSB_ERROR_NO_DEVICE";
1897 case LIBUSB_ERROR_NOT_FOUND:
1898 return "LIBUSB_ERROR_NOT_FOUND";
1899 case LIBUSB_ERROR_BUSY:
1900 return "LIBUSB_ERROR_BUSY";
1901 case LIBUSB_ERROR_TIMEOUT:
1902 return "LIBUSB_ERROR_TIMEOUT";
1903 case LIBUSB_ERROR_OVERFLOW:
1904 return "LIBUSB_ERROR_OVERFLOW";
1905 case LIBUSB_ERROR_PIPE:
1906 return "LIBUSB_ERROR_PIPE";
1907 case LIBUSB_ERROR_INTERRUPTED:
1908 return "LIBUSB_ERROR_INTERRUPTED";
1909 case LIBUSB_ERROR_NO_MEM:
1910 return "LIBUSB_ERROR_NO_MEM";
1911 case LIBUSB_ERROR_NOT_SUPPORTED:
1912 return "LIBUSB_ERROR_NOT_SUPPORTED";
1913 case LIBUSB_ERROR_OTHER:
1914 return "LIBUSB_ERROR_OTHER";
1916 return "**UNKNOWN**";
1920 * Returns a pointer to const struct libusb_version with the version
1921 * (major, minor, micro, nano and rc) of the running library.
1924 const struct libusb_version * LIBUSB_CALL libusb_get_version(void)
1926 return &libusb_version_internal;