/*
* Core functions for libusb
* Copyright (C) 2007-2008 Daniel Drake <dsd@gentoo.org>
* Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <config.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include "libusbi.h"
#if defined(OS_LINUX)
const struct usbi_os_backend * const usbi_backend = &linux_usbfs_backend;
#elif defined(OS_DARWIN)
const struct usbi_os_backend * const usbi_backend = &darwin_backend;
#elif defined(OS_WINDOWS)
const struct usbi_os_backend * const usbi_backend = &windows_backend;
#else
#error "Unsupported OS"
#endif
struct libusb_context *usbi_default_context = NULL;
const struct libusb_version libusb_version_internal = { LIBUSB_VERSION_MAJOR,
LIBUSB_VERSION_MINOR, LIBUSB_VERSION_MICRO, LIBUSB_VERSION_NANO};
static int default_context_refcnt = 0;
static usbi_mutex_static_t default_context_lock = USBI_MUTEX_INITIALIZER;
/**
* \mainpage libusb-1.0 API Reference
*
* \section intro Introduction
*
* libusb is an open source library that allows you to communicate with USB
* devices from userspace. For more info, see the
* <a href="http://libusb.sourceforge.net">libusb homepage</a>.
*
* This documentation is aimed at application developers wishing to
* communicate with USB peripherals from their own software. After reviewing
* this documentation, feedback and questions can be sent to the
* <a href="http://sourceforge.net/mail/?group_id=1674">libusb-devel mailing
* list</a>.
*
* This documentation assumes knowledge of how to operate USB devices from
* a software standpoint (descriptors, configurations, interfaces, endpoints,
* control/bulk/interrupt/isochronous transfers, etc). Full information
* can be found in the <a href="http://www.usb.org/developers/docs/">USB 2.0
* Specification</a> which is available for free download. You can probably
* find less verbose introductions by searching the web.
*
* \section features Library features
*
* - All transfer types supported (control/bulk/interrupt/isochronous)
* - 2 transfer interfaces:
* -# Synchronous (simple)
* -# Asynchronous (more complicated, but more powerful)
* - Thread safe (although the asynchronous interface means that you
* usually won't need to thread)
* - Lightweight with lean API
* - Compatible with libusb-0.1 through the libusb-compat-0.1 translation layer
*
* \section gettingstarted Getting Started
*
* To begin reading the API documentation, start with the Modules page which
* links to the different categories of libusb's functionality.
*
* One decision you will have to make is whether to use the synchronous
* or the asynchronous data transfer interface. The \ref io documentation
* provides some insight into this topic.
*
* Some example programs can be found in the libusb source distribution under
* the "examples" subdirectory. The libusb homepage includes a list of
* real-life project examples which use libusb.
*
* \section errorhandling Error handling
*
* libusb functions typically return 0 on success or a negative error code
* on failure. These negative error codes relate to LIBUSB_ERROR constants
* which are listed on the \ref misc "miscellaneous" documentation page.
*
* \section msglog Debug message logging
*
* libusb does not log any messages by default. Your application is therefore
* free to close stdout/stderr and those descriptors may be reused without
* worry.
*
* The libusb_set_debug() function can be used to enable stdout/stderr logging
* of certain messages. Under standard configuration, libusb doesn't really
* log much at all, so you are advised to use this function to enable all
* error/warning/informational messages. It will help you debug problems with
* your software.
*
* The logged messages are unstructured. There is no one-to-one correspondence
* between messages being logged and success or failure return codes from
* libusb functions. There is no format to the messages, so you should not
* try to capture or parse them. They are not and will not be localized.
* These messages are not suitable for being passed to your application user;
* instead, you should interpret the error codes returned from libusb functions
* and provide appropriate notification to the user. The messages are simply
* there to aid you as a programmer, and if you're confused because you're
* getting a strange error code from a libusb function, enabling message
* logging may give you a suitable explanation.
*
* The LIBUSB_DEBUG environment variable can be used to enable message logging
* at run-time. This environment variable should be set to a number, which is
* interpreted the same as the libusb_set_debug() parameter. When this
* environment variable is set, the message logging verbosity level is fixed
* and libusb_set_debug() effectively does nothing.
*
* libusb can be compiled without any logging functions, useful for embedded
* systems. In this case, libusb_set_debug() and the LIBUSB_DEBUG environment
* variable have no effects.
*
* libusb can also be compiled with verbose debugging messages. When the
* library is compiled in this way, all messages of all verbosities are always
* logged. libusb_set_debug() and the LIBUSB_DEBUG environment variable have
* no effects.
*
* \section remarks Other remarks
*
* libusb does have imperfections. The \ref caveats "caveats" page attempts
* to document these.
*/
/**
* \page caveats Caveats
*
* \section devresets Device resets
*
* The libusb_reset_device() function allows you to reset a device. If your
* program has to call such a function, it should obviously be aware that
* the reset will cause device state to change (e.g. register values may be
* reset).
*
* The problem is that any other program could reset the device your program
* is working with, at any time. libusb does not offer a mechanism to inform
* you when this has happened, so if someone else resets your device it will
* not be clear to your own program why the device state has changed.
*
* Ultimately, this is a limitation of writing drivers in userspace.
* Separation from the USB stack in the underlying kernel makes it difficult
* for the operating system to deliver such notifications to your program.
* The Linux kernel USB stack allows such reset notifications to be delivered
* to in-kernel USB drivers, but it is not clear how such notifications could
* be delivered to second-class drivers that live in userspace.
*
* \section blockonly Blocking-only functionality
*
* The functionality listed below is only available through synchronous,
* blocking functions. There are no asynchronous/non-blocking alternatives,
* and no clear ways of implementing these.
*
* - Configuration activation (libusb_set_configuration())
* - Interface/alternate setting activation (libusb_set_interface_alt_setting())
* - Releasing of interfaces (libusb_release_interface())
* - Clearing of halt/stall condition (libusb_clear_halt())
* - Device resets (libusb_reset_device())
*
* \section nohotplug No hotplugging
*
* libusb-1.0 lacks functionality for providing notifications of when devices
* are added or removed. This functionality is planned to be implemented
* for libusb-1.1.
*
* That said, there is basic disconnection handling for open device handles:
* - If there are ongoing transfers, libusb's handle_events loop will detect
* disconnections and complete ongoing transfers with the
* LIBUSB_TRANSFER_NO_DEVICE status code.
* - Many functions such as libusb_set_configuration() return the special
* LIBUSB_ERROR_NO_DEVICE error code when the device has been disconnected.
*
* \section configsel Configuration selection and handling
*
* When libusb presents a device handle to an application, there is a chance
* that the corresponding device may be in unconfigured state. For devices
* with multiple configurations, there is also a chance that the configuration
* currently selected is not the one that the application wants to use.
*
* The obvious solution is to add a call to libusb_set_configuration() early
* on during your device initialization routines, but there are caveats to
* be aware of:
* -# If the device is already in the desired configuration, calling
* libusb_set_configuration() using the same configuration value will cause
* a lightweight device reset. This may not be desirable behaviour.
* -# libusb will be unable to change configuration if the device is in
* another configuration and other programs or drivers have claimed
* interfaces under that configuration.
* -# In the case where the desired configuration is already active, libusb
* may not even be able to perform a lightweight device reset. For example,
* take my USB keyboard with fingerprint reader: I'm interested in driving
* the fingerprint reader interface through libusb, but the kernel's
* USB-HID driver will almost always have claimed the keyboard interface.
* Because the kernel has claimed an interface, it is not even possible to
* perform the lightweight device reset, so libusb_set_configuration() will
* fail. (Luckily the device in question only has a single configuration.)
*
* One solution to some of the above problems is to consider the currently
* active configuration. If the configuration we want is already active, then
* we don't have to select any configuration:
\code
cfg = libusb_get_configuration(dev);
if (cfg != desired)
libusb_set_configuration(dev, desired);
\endcode
*
* This is probably suitable for most scenarios, but is inherently racy:
* another application or driver may change the selected configuration
* <em>after</em> the libusb_get_configuration() call.
*
* Even in cases where libusb_set_configuration() succeeds, consider that other
* applications or drivers may change configuration after your application
* calls libusb_set_configuration().
*
* One possible way to lock your device into a specific configuration is as
* follows:
* -# Set the desired configuration (or use the logic above to realise that
* it is already in the desired configuration)
* -# Claim the interface that you wish to use
* -# Check that the currently active configuration is the one that you want
* to use.
*
* The above method works because once an interface is claimed, no application
* or driver is able to select another configuration.
*
* \section earlycomp Early transfer completion
*
* NOTE: This section is currently Linux-centric. I am not sure if any of these
* considerations apply to Darwin or other platforms.
*
* When a transfer completes early (i.e. when less data is received/sent in
* any one packet than the transfer buffer allows for) then libusb is designed
* to terminate the transfer immediately, not transferring or receiving any
* more data unless other transfers have been queued by the user.
*
* On legacy platforms, libusb is unable to do this in all situations. After
* the incomplete packet occurs, "surplus" data may be transferred. Prior to
* libusb v1.0.2, this information was lost (and for device-to-host transfers,
* the corresponding data was discarded). As of libusb v1.0.3, this information
* is kept (the data length of the transfer is updated) and, for device-to-host
* transfers, any surplus data was added to the buffer. Still, this is not
* a nice solution because it loses the information about the end of the short
* packet, and the user probably wanted that surplus data to arrive in the next
* logical transfer.
*
* A previous workaround was to only ever submit transfers of size 16kb or
* less.
*
* As of libusb v1.0.4 and Linux v2.6.32, this is fixed. A technical
* explanation of this issue follows.
*
* When you ask libusb to submit a bulk transfer larger than 16kb in size,
* libusb breaks it up into a number of smaller subtransfers. This is because
* the usbfs kernel interface only accepts transfers of up to 16kb in size.
* The subtransfers are submitted all at once so that the kernel can queue
* them at the hardware level, therefore maximizing bus throughput.
*
* On legacy platforms, this caused problems when transfers completed early.
* Upon this event, the kernel would terminate all further packets in that
* subtransfer (but not any following ones). libusb would note this event and
* immediately cancel any following subtransfers that had been queued,
* but often libusb was not fast enough, and the following subtransfers had
* started before libusb got around to cancelling them.
*
* Thanks to an API extension to usbfs, this is fixed with recent kernel and
* libusb releases. The solution was to allow libusb to communicate to the
* kernel where boundaries occur between logical libusb-level transfers. When
* a short transfer (or other error) occurs, the kernel will cancel all the
* subtransfers until the boundary without allowing those transfers to start.
*/
/**
* \page contexts Contexts
*
* It is possible that libusb may be used simultaneously from two independent
* libraries linked into the same executable. For example, if your application
* has a plugin-like system which allows the user to dynamically load a range
* of modules into your program, it is feasible that two independently
* developed modules may both use libusb.
*
* libusb is written to allow for these multiple user scenarios. The two
* "instances" of libusb will not interfere: libusb_set_debug() calls
* from one user will not affect the same settings for other users, other
* users can continue using libusb after one of them calls libusb_exit(), etc.
*
* This is made possible through libusb's <em>context</em> concept. When you
* call libusb_init(), you are (optionally) given a context. You can then pass
* this context pointer back into future libusb functions.
*
* In order to keep things simple for more simplistic applications, it is
* legal to pass NULL to all functions requiring a context pointer (as long as
* you're sure no other code will attempt to use libusb from the same process).
* When you pass NULL, the default context will be used. The default context
* is created the first time a process calls libusb_init() when no other
* context is alive. Contexts are destroyed during libusb_exit().
*
* The default context is reference-counted and can be shared. That means that
* if libusb_init(NULL) is called twice within the same process, the two
* users end up sharing the same context. The deinitialization and freeing of
* the default context will only happen when the last user calls libusb_exit().
* In other words, the default context is created and initialized when its
* reference count goes from 0 to 1, and is deinitialized and destroyed when
* its reference count goes from 1 to 0.
*
* You may be wondering why only a subset of libusb functions require a
* context pointer in their function definition. Internally, libusb stores
* context pointers in other objects (e.g. libusb_device instances) and hence
* can infer the context from those objects.
*/
/**
* @defgroup lib Library initialization/deinitialization
* This page details how to initialize and deinitialize libusb. Initialization
* must be performed before using any libusb functionality, and similarly you
* must not call any libusb functions after deinitialization.
*/
/**
* @defgroup dev Device handling and enumeration
* The functionality documented below is designed to help with the following
* operations:
* - Enumerating the USB devices currently attached to the system
* - Choosing a device to operate from your software
* - Opening and closing the chosen device
*
* \section nutshell In a nutshell...
*
* The description below really makes things sound more complicated than they
* actually are. The following sequence of function calls will be suitable
* for almost all scenarios and does not require you to have such a deep
* understanding of the resource management issues:
* \code
// discover devices
libusb_device **list;
libusb_device *found = NULL;
ssize_t cnt = libusb_get_device_list(NULL, &list);
ssize_t i = 0;
int err = 0;
if (cnt < 0)
error();
for (i = 0; i < cnt; i++) {
libusb_device *device = list[i];
if (is_interesting(device)) {
found = device;
break;
}
}
if (found) {
libusb_device_handle *handle;
err = libusb_open(found, &handle);
if (err)
error();
// etc
}
libusb_free_device_list(list, 1);
\endcode
*
* The two important points:
* - You asked libusb_free_device_list() to unreference the devices (2nd
* parameter)
* - You opened the device before freeing the list and unreferencing the
* devices
*
* If you ended up with a handle, you can now proceed to perform I/O on the
* device.
*
* \section devshandles Devices and device handles
* libusb has a concept of a USB device, represented by the
* \ref libusb_device opaque type. A device represents a USB device that
* is currently or was previously connected to the system. Using a reference
* to a device, you can determine certain information about the device (e.g.
* you can read the descriptor data).
*
* The libusb_get_device_list() function can be used to obtain a list of
* devices currently connected to the system. This is known as device
* discovery.
*
* Just because you have a reference to a device does not mean it is
* necessarily usable. The device may have been unplugged, you may not have
* permission to operate such device, or another program or driver may be
* using the device.
*
* When you've found a device that you'd like to operate, you must ask
* libusb to open the device using the libusb_open() function. Assuming
* success, libusb then returns you a <em>device handle</em>
* (a \ref libusb_device_handle pointer). All "real" I/O operations then
* operate on the handle rather than the original device pointer.
*
* \section devref Device discovery and reference counting
*
* Device discovery (i.e. calling libusb_get_device_list()) returns a
* freshly-allocated list of devices. The list itself must be freed when
* you are done with it. libusb also needs to know when it is OK to free
* the contents of the list - the devices themselves.
*
* To handle these issues, libusb provides you with two separate items:
* - A function to free the list itself
* - A reference counting system for the devices inside
*
* New devices presented by the libusb_get_device_list() function all have a
* reference count of 1. You can increase and decrease reference count using
* libusb_ref_device() and libusb_unref_device(). A device is destroyed when
* its reference count reaches 0.
*
* With the above information in mind, the process of opening a device can
* be viewed as follows:
* -# Discover devices using libusb_get_device_list().
* -# Choose the device that you want to operate, and call libusb_open().
* -# Unref all devices in the discovered device list.
* -# Free the discovered device list.
*
* The order is important - you must not unreference the device before
* attempting to open it, because unreferencing it may destroy the device.
*
* For convenience, the libusb_free_device_list() function includes a
* parameter to optionally unreference all the devices in the list before
* freeing the list itself. This combines steps 3 and 4 above.
*
* As an implementation detail, libusb_open() actually adds a reference to
* the device in question. This is because the device remains available
* through the handle via libusb_get_device(). The reference is deleted during
* libusb_close().
*/
/** @defgroup misc Miscellaneous */
/* we traverse usbfs without knowing how many devices we are going to find.
* so we create this discovered_devs model which is similar to a linked-list
* which grows when required. it can be freed once discovery has completed,
* eliminating the need for a list node in the libusb_device structure
* itself. */
#define DISCOVERED_DEVICES_SIZE_STEP 8
static struct discovered_devs *discovered_devs_alloc(void)
{
struct discovered_devs *ret =
malloc(sizeof(*ret) + (sizeof(void *) * DISCOVERED_DEVICES_SIZE_STEP));
if (ret) {
ret->len = 0;
ret->capacity = DISCOVERED_DEVICES_SIZE_STEP;
}
return ret;
}
/* append a device to the discovered devices collection. may realloc itself,
* returning new discdevs. returns NULL on realloc failure. */
struct discovered_devs *discovered_devs_append(
struct discovered_devs *discdevs, struct libusb_device *dev)
{
size_t len = discdevs->len;
size_t capacity;
/* if there is space, just append the device */
if (len < discdevs->capacity) {
discdevs->devices[len] = libusb_ref_device(dev);
discdevs->len++;
return discdevs;
}
/* exceeded capacity, need to grow */
usbi_dbg("need to increase capacity");
capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
discdevs = realloc(discdevs,
sizeof(*discdevs) + (sizeof(void *) * capacity));
if (discdevs) {
discdevs->capacity = capacity;
discdevs->devices[len] = libusb_ref_device(dev);
discdevs->len++;
}
return discdevs;
}
static void discovered_devs_free(struct discovered_devs *discdevs)
{
size_t i;
for (i = 0; i < discdevs->len; i++)
libusb_unref_device(discdevs->devices[i]);
free(discdevs);
}
/* Allocate a new device with a specific session ID. The returned device has
* a reference count of 1. */
struct libusb_device *usbi_alloc_device(struct libusb_context *ctx,
unsigned long session_id)
{
size_t priv_size = usbi_backend->device_priv_size;
struct libusb_device *dev = malloc(sizeof(*dev) + priv_size);
int r;
if (!dev)
return NULL;
r = usbi_mutex_init(&dev->lock, NULL);
if (r) {
free(dev);
return NULL;
}
dev->ctx = ctx;
dev->refcnt = 1;
dev->session_data = session_id;
memset(&dev->os_priv, 0, priv_size);
usbi_mutex_lock(&ctx->usb_devs_lock);
list_add(&dev->list, &ctx->usb_devs);
usbi_mutex_unlock(&ctx->usb_devs_lock);
return dev;
}
/* Perform some final sanity checks on a newly discovered device. If this
* function fails (negative return code), the device should not be added
* to the discovered device list. */
int usbi_sanitize_device(struct libusb_device *dev)
{
int r;
unsigned char raw_desc[DEVICE_DESC_LENGTH];
uint8_t num_configurations;
int host_endian;
r = usbi_backend->get_device_descriptor(dev, raw_desc, &host_endian);
if (r < 0)
return r;
num_configurations = raw_desc[DEVICE_DESC_LENGTH - 1];
if (num_configurations > USB_MAXCONFIG) {
usbi_err(DEVICE_CTX(dev), "too many configurations");
return LIBUSB_ERROR_IO;
} else if (num_configurations < 1) {
usbi_dbg("no configurations?");
return LIBUSB_ERROR_IO;
}
dev->num_configurations = num_configurations;
return 0;
}
/* Examine libusb's internal list of known devices, looking for one with
* a specific session ID. Returns the matching device if it was found, and
* NULL otherwise. */
struct libusb_device *usbi_get_device_by_session_id(struct libusb_context *ctx,
unsigned long session_id)
{
struct libusb_device *dev;
struct libusb_device *ret = NULL;
usbi_mutex_lock(&ctx->usb_devs_lock);
list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device)
if (dev->session_data == session_id) {
ret = dev;
break;
}
usbi_mutex_unlock(&ctx->usb_devs_lock);
return ret;
}
/** @ingroup dev
* Returns a list of USB devices currently attached to the system. This is
* your entry point into finding a USB device to operate.
*
* You are expected to unreference all the devices when you are done with
* them, and then free the list with libusb_free_device_list(). Note that
* libusb_free_device_list() can unref all the devices for you. Be careful
* not to unreference a device you are about to open until after you have
* opened it.
*
* This return value of this function indicates the number of devices in
* the resultant list. The list is actually one element larger, as it is
* NULL-terminated.
*
* \param ctx the context to operate on, or NULL for the default context
* \param list output location for a list of devices. Must be later freed with
* libusb_free_device_list().
* \returns the number of devices in the outputted list, or LIBUSB_ERROR_NO_MEM
* on memory allocation failure.
*/
ssize_t API_EXPORTED libusb_get_device_list(libusb_context *ctx,
libusb_device ***list)
{
struct discovered_devs *discdevs = discovered_devs_alloc();
struct libusb_device **ret;
int r = 0;
ssize_t i, len;
USBI_GET_CONTEXT(ctx);
usbi_dbg("");
if (!discdevs)
return LIBUSB_ERROR_NO_MEM;
r = usbi_backend->get_device_list(ctx, &discdevs);
if (r < 0) {
len = r;
goto out;
}
/* convert discovered_devs into a list */
len = discdevs->len;
ret = malloc(sizeof(void *) * (len + 1));
if (!ret) {
len = LIBUSB_ERROR_NO_MEM;
goto out;
}
ret[len] = NULL;
for (i = 0; i < len; i++) {
struct libusb_device *dev = discdevs->devices[i];
ret[i] = libusb_ref_device(dev);
}
*list = ret;
out:
discovered_devs_free(discdevs);
return len;
}
/** \ingroup dev
* Frees a list of devices previously discovered using
* libusb_get_device_list(). If the unref_devices parameter is set, the
* reference count of each device in the list is decremented by 1.
* \param list the list to free
* \param unref_devices whether to unref the devices in the list
*/
void API_EXPORTED libusb_free_device_list(libusb_device **list,
int unref_devices)
{
if (!list)
return;
if (unref_devices) {
int i = 0;
struct libusb_device *dev;
while ((dev = list[i++]) != NULL)
libusb_unref_device(dev);
}
free(list);
}
/** \ingroup dev
* Get the number of the bus that a device is connected to.
* \param dev a device
* \returns the bus number
*/
uint8_t API_EXPORTED libusb_get_bus_number(libusb_device *dev)
{
return dev->bus_number;
}
/** \ingroup dev
* Get the address of the device on the bus it is connected to.
* \param dev a device
* \returns the device address
*/
uint8_t API_EXPORTED libusb_get_device_address(libusb_device *dev)
{
return dev->device_address;
}
static const struct libusb_endpoint_descriptor *find_endpoint(
struct libusb_config_descriptor *config, unsigned char endpoint)
{
int iface_idx;
for (iface_idx = 0; iface_idx < config->bNumInterfaces; iface_idx++) {
const struct libusb_interface *iface = &config->interface[iface_idx];
int altsetting_idx;
for (altsetting_idx = 0; altsetting_idx < iface->num_altsetting;
altsetting_idx++) {
const struct libusb_interface_descriptor *altsetting
= &iface->altsetting[altsetting_idx];
int ep_idx;
for (ep_idx = 0; ep_idx < altsetting->bNumEndpoints; ep_idx++) {
const struct libusb_endpoint_descriptor *ep =
&altsetting->endpoint[ep_idx];
if (ep->bEndpointAddress == endpoint)
return ep;
}
}
}
return NULL;
}
/** \ingroup dev
* Convenience function to retrieve the wMaxPacketSize value for a particular
* endpoint in the active device configuration.
*
* This function was originally intended to be of assistance when setting up
* isochronous transfers, but a design mistake resulted in this function
* instead. It simply returns the wMaxPacketSize value without considering
* its contents. If you're dealing with isochronous transfers, you probably
* want libusb_get_max_iso_packet_size() instead.
*
* \param dev a device
* \param endpoint address of the endpoint in question
* \returns the wMaxPacketSize value
* \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
* \returns LIBUSB_ERROR_OTHER on other failure
*/
int API_EXPORTED libusb_get_max_packet_size(libusb_device *dev,
unsigned char endpoint)
{
struct libusb_config_descriptor *config;
const struct libusb_endpoint_descriptor *ep;
int r;
r = libusb_get_active_config_descriptor(dev, &config);
if (r < 0) {
usbi_err(DEVICE_CTX(dev),
"could not retrieve active config descriptor");
return LIBUSB_ERROR_OTHER;
}
ep = find_endpoint(config, endpoint);
if (!ep)
return LIBUSB_ERROR_NOT_FOUND;
r = ep->wMaxPacketSize;
libusb_free_config_descriptor(config);
return r;
}
/** \ingroup dev
* Calculate the maximum packet size which a specific endpoint is capable is
* sending or receiving in the duration of 1 microframe
*
* Only the active configution is examined. The calculation is based on the
* wMaxPacketSize field in the endpoint descriptor as described in section
* 9.6.6 in the USB 2.0 specifications.
*
* If acting on an isochronous or interrupt endpoint, this function will
* multiply the value found in bits 0:10 by the number of transactions per
* microframe (determined by bits 11:12). Otherwise, this function just
* returns the numeric value found in bits 0:10.
*
* This function is useful for setting up isochronous transfers, for example
* you might pass the return value from this function to
* libusb_set_iso_packet_lengths() in order to set the length field of every
* isochronous packet in a transfer.
*
* Since v1.0.3.
*
* \param dev a device
* \param endpoint address of the endpoint in question
* \returns the maximum packet size which can be sent/received on this endpoint
* \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
* \returns LIBUSB_ERROR_OTHER on other failure
*/
int API_EXPORTED libusb_get_max_iso_packet_size(libusb_device *dev,
unsigned char endpoint)
{
struct libusb_config_descriptor *config;
const struct libusb_endpoint_descriptor *ep;
enum libusb_transfer_type ep_type;
uint16_t val;
int r;
r = libusb_get_active_config_descriptor(dev, &config);
if (r < 0) {
usbi_err(DEVICE_CTX(dev),
"could not retrieve active config descriptor");
return LIBUSB_ERROR_OTHER;
}
ep = find_endpoint(config, endpoint);
if (!ep)
return LIBUSB_ERROR_NOT_FOUND;
val = ep->wMaxPacketSize;
ep_type = ep->bmAttributes & 0x3;
libusb_free_config_descriptor(config);
r = val & 0x07ff;
if (ep_type == LIBUSB_TRANSFER_TYPE_ISOCHRONOUS
|| ep_type == LIBUSB_TRANSFER_TYPE_INTERRUPT)
r *= (1 + ((val >> 11) & 3));
return r;
}
/** \ingroup dev
* Increment the reference count of a device.
* \param dev the device to reference
* \returns the same device
*/
DEFAULT_VISIBILITY
libusb_device * LIBUSB_CALL libusb_ref_device(libusb_device *dev)
{
usbi_mutex_lock(&dev->lock);
dev->refcnt++;
usbi_mutex_unlock(&dev->lock);
return dev;
}
/** \ingroup dev
* Decrement the reference count of a device. If the decrement operation
* causes the reference count to reach zero, the device shall be destroyed.
* \param dev the device to unreference
*/
void API_EXPORTED libusb_unref_device(libusb_device *dev)
{
int refcnt;
if (!dev)
return;
usbi_mutex_lock(&dev->lock);
refcnt = --dev->refcnt;
usbi_mutex_unlock(&dev->lock);
if (refcnt == 0) {
usbi_dbg("destroy device %d.%d", dev->bus_number, dev->device_address);
if (usbi_backend->destroy_device)
usbi_backend->destroy_device(dev);
usbi_mutex_lock(&dev->ctx->usb_devs_lock);
list_del(&dev->list);
usbi_mutex_unlock(&dev->ctx->usb_devs_lock);
usbi_mutex_destroy(&dev->lock);
free(dev);
}
}
/*
* Interrupt the iteration of the event handling thread, so that it picks
* up the new fd.
*/
void usbi_fd_notification(struct libusb_context *ctx)
{
unsigned char dummy = 1;
ssize_t r;
if (ctx == NULL)
return;
/* record that we are messing with poll fds */
usbi_mutex_lock(&ctx->pollfd_modify_lock);
ctx->pollfd_modify++;
usbi_mutex_unlock(&ctx->pollfd_modify_lock);
/* write some data on control pipe to interrupt event handlers */
r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
if (r <= 0) {
usbi_warn(ctx, "internal signalling write failed");
usbi_mutex_lock(&ctx->pollfd_modify_lock);
ctx->pollfd_modify--;
usbi_mutex_unlock(&ctx->pollfd_modify_lock);
return;
}
/* take event handling lock */
libusb_lock_events(ctx);
/* read the dummy data */
r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
if (r <= 0)
usbi_warn(ctx, "internal signalling read failed");
/* we're done with modifying poll fds */
usbi_mutex_lock(&ctx->pollfd_modify_lock);
ctx->pollfd_modify--;
usbi_mutex_unlock(&ctx->pollfd_modify_lock);
/* Release event handling lock and wake up event waiters */
libusb_unlock_events(ctx);
}
/** \ingroup dev
* Open a device and obtain a device handle. A handle allows you to perform
* I/O on the device in question.
*
* Internally, this function adds a reference to the device and makes it
* available to you through libusb_get_device(). This reference is removed
* during libusb_close().
*
* This is a non-blocking function; no requests are sent over the bus.
*
* \param dev the device to open
* \param handle output location for the returned device handle pointer. Only
* populated when the return code is 0.
* \returns 0 on success
* \returns LIBUSB_ERROR_NO_MEM on memory allocation failure
* \returns LIBUSB_ERROR_ACCESS if the user has insufficient permissions
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns another LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_open(libusb_device *dev,
libusb_device_handle **handle)
{
struct libusb_context *ctx = DEVICE_CTX(dev);
struct libusb_device_handle *_handle;
size_t priv_size = usbi_backend->device_handle_priv_size;
int r;
usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);
_handle = malloc(sizeof(*_handle) + priv_size);
if (!_handle)
return LIBUSB_ERROR_NO_MEM;
r = usbi_mutex_init(&_handle->lock, NULL);
if (r) {
free(_handle);
return LIBUSB_ERROR_OTHER;
}
_handle->dev = libusb_ref_device(dev);
_handle->claimed_interfaces = 0;
memset(&_handle->os_priv, 0, priv_size);
r = usbi_backend->open(_handle);
if (r < 0) {
libusb_unref_device(dev);
usbi_mutex_destroy(&_handle->lock);
free(_handle);
return r;
}
usbi_mutex_lock(&ctx->open_devs_lock);
list_add(&_handle->list, &ctx->open_devs);
usbi_mutex_unlock(&ctx->open_devs_lock);
*handle = _handle;
/* At this point, we want to interrupt any existing event handlers so
* that they realise the addition of the new device's poll fd. One
* example when this is desirable is if the user is running a separate
* dedicated libusb events handling thread, which is running with a long
* or infinite timeout. We want to interrupt that iteration of the loop,
* so that it picks up the new fd, and then continues. */
usbi_fd_notification(ctx);
return 0;
}
/** \ingroup dev
* Convenience function for finding a device with a particular
* <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
* for those scenarios where you are using libusb to knock up a quick test
* application - it allows you to avoid calling libusb_get_device_list() and
* worrying about traversing/freeing the list.
*
* This function has limitations and is hence not intended for use in real
* applications: if multiple devices have the same IDs it will only
* give you the first one, etc.
*
* \param ctx the context to operate on, or NULL for the default context
* \param vendor_id the idVendor value to search for
* \param product_id the idProduct value to search for
* \returns a handle for the first found device, or NULL on error or if the
* device could not be found. */
DEFAULT_VISIBILITY
libusb_device_handle * LIBUSB_CALL libusb_open_device_with_vid_pid(
libusb_context *ctx, uint16_t vendor_id, uint16_t product_id)
{
struct libusb_device **devs;
struct libusb_device *found = NULL;
struct libusb_device *dev;
struct libusb_device_handle *handle = NULL;
size_t i = 0;
int r;
if (libusb_get_device_list(ctx, &devs) < 0)
return NULL;
while ((dev = devs[i++]) != NULL) {
struct libusb_device_descriptor desc;
r = libusb_get_device_descriptor(dev, &desc);
if (r < 0)
goto out;
if (desc.idVendor == vendor_id && desc.idProduct == product_id) {
found = dev;
break;
}
}
if (found) {
r = libusb_open(found, &handle);
if (r < 0)
handle = NULL;
}
out:
libusb_free_device_list(devs, 1);
return handle;
}
static void do_close(struct libusb_context *ctx,
struct libusb_device_handle *dev_handle)
{
usbi_mutex_lock(&ctx->open_devs_lock);
list_del(&dev_handle->list);
usbi_mutex_unlock(&ctx->open_devs_lock);
usbi_backend->close(dev_handle);
libusb_unref_device(dev_handle->dev);
usbi_mutex_destroy(&dev_handle->lock);
free(dev_handle);
}
/** \ingroup dev
* Close a device handle. Should be called on all open handles before your
* application exits.
*
* Internally, this function destroys the reference that was added by
* libusb_open() on the given device.
*
* This is a non-blocking function; no requests are sent over the bus.
*
* \param dev_handle the handle to close
*/
void API_EXPORTED libusb_close(libusb_device_handle *dev_handle)
{
struct libusb_context *ctx;
unsigned char dummy = 1;
ssize_t r;
if (!dev_handle)
return;
usbi_dbg("");
ctx = HANDLE_CTX(dev_handle);
/* Similarly to libusb_open(), we want to interrupt all event handlers
* at this point. More importantly, we want to perform the actual close of
* the device while holding the event handling lock (preventing any other
* thread from doing event handling) because we will be removing a file
* descriptor from the polling loop. */
/* record that we are messing with poll fds */
usbi_mutex_lock(&ctx->pollfd_modify_lock);
ctx->pollfd_modify++;
usbi_mutex_unlock(&ctx->pollfd_modify_lock);
/* write some data on control pipe to interrupt event handlers */
r = usbi_write(ctx->ctrl_pipe[1], &dummy, sizeof(dummy));
if (r <= 0) {
usbi_warn(ctx, "internal signalling write failed, closing anyway");
do_close(ctx, dev_handle);
usbi_mutex_lock(&ctx->pollfd_modify_lock);
ctx->pollfd_modify--;
usbi_mutex_unlock(&ctx->pollfd_modify_lock);
return;
}
/* take event handling lock */
libusb_lock_events(ctx);
/* read the dummy data */
r = usbi_read(ctx->ctrl_pipe[0], &dummy, sizeof(dummy));
if (r <= 0)
usbi_warn(ctx, "internal signalling read failed, closing anyway");
/* Close the device */
do_close(ctx, dev_handle);
/* we're done with modifying poll fds */
usbi_mutex_lock(&ctx->pollfd_modify_lock);
ctx->pollfd_modify--;
usbi_mutex_unlock(&ctx->pollfd_modify_lock);
/* Release event handling lock and wake up event waiters */
libusb_unlock_events(ctx);
}
/** \ingroup dev
* Get the underlying device for a handle. This function does not modify
* the reference count of the returned device, so do not feel compelled to
* unreference it when you are done.
* \param dev_handle a device handle
* \returns the underlying device
*/
DEFAULT_VISIBILITY
libusb_device * LIBUSB_CALL libusb_get_device(libusb_device_handle *dev_handle)
{
return dev_handle->dev;
}
/** \ingroup dev
* Determine the bConfigurationValue of the currently active configuration.
*
* You could formulate your own control request to obtain this information,
* but this function has the advantage that it may be able to retrieve the
* information from operating system caches (no I/O involved).
*
* If the OS does not cache this information, then this function will block
* while a control transfer is submitted to retrieve the information.
*
* This function will return a value of 0 in the <tt>config</tt> output
* parameter if the device is in unconfigured state.
*
* \param dev a device handle
* \param config output location for the bConfigurationValue of the active
* configuration (only valid for return code 0)
* \returns 0 on success
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns another LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_get_configuration(libusb_device_handle *dev,
int *config)
{
int r = LIBUSB_ERROR_NOT_SUPPORTED;
usbi_dbg("");
if (usbi_backend->get_configuration)
r = usbi_backend->get_configuration(dev, config);
if (r == LIBUSB_ERROR_NOT_SUPPORTED) {
uint8_t tmp = 0;
usbi_dbg("falling back to control message");
r = libusb_control_transfer(dev, LIBUSB_ENDPOINT_IN,
LIBUSB_REQUEST_GET_CONFIGURATION, 0, 0, &tmp, 1, 1000);
if (r == 0) {
usbi_err(HANDLE_CTX(dev), "zero bytes returned in ctrl transfer?");
r = LIBUSB_ERROR_IO;
} else if (r == 1) {
r = 0;
*config = tmp;
} else {
usbi_dbg("control failed, error %d", r);
}
}
if (r == 0)
usbi_dbg("active config %d", *config);
return r;
}
/** \ingroup dev
* Set the active configuration for a device.
*
* The operating system may or may not have already set an active
* configuration on the device. It is up to your application to ensure the
* correct configuration is selected before you attempt to claim interfaces
* and perform other operations.
*
* If you call this function on a device already configured with the selected
* configuration, then this function will act as a lightweight device reset:
* it will issue a SET_CONFIGURATION request using the current configuration,
* causing most USB-related device state to be reset (altsetting reset to zero,
* endpoint halts cleared, toggles reset).
*
* You cannot change/reset configuration if your application has claimed
* interfaces - you should free them with libusb_release_interface() first.
* You cannot change/reset configuration if other applications or drivers have
* claimed interfaces.
*
* A configuration value of -1 will put the device in unconfigured state.
* The USB specifications state that a configuration value of 0 does this,
* however buggy devices exist which actually have a configuration 0.
*
* You should always use this function rather than formulating your own
* SET_CONFIGURATION control request. This is because the underlying operating
* system needs to know when such changes happen.
*
* This is a blocking function.
*
* \param dev a device handle
* \param configuration the bConfigurationValue of the configuration you
* wish to activate, or -1 if you wish to put the device in unconfigured state
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if the requested configuration does not exist
* \returns LIBUSB_ERROR_BUSY if interfaces are currently claimed
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns another LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_set_configuration(libusb_device_handle *dev,
int configuration)
{
usbi_dbg("configuration %d", configuration);
return usbi_backend->set_configuration(dev, configuration);
}
/** \ingroup dev
* Claim an interface on a given device handle. You must claim the interface
* you wish to use before you can perform I/O on any of its endpoints.
*
* It is legal to attempt to claim an already-claimed interface, in which
* case libusb just returns 0 without doing anything.
*
* Claiming of interfaces is a purely logical operation; it does not cause
* any requests to be sent over the bus. Interface claiming is used to
* instruct the underlying operating system that your application wishes
* to take ownership of the interface.
*
* This is a non-blocking function.
*
* \param dev a device handle
* \param interface_number the <tt>bInterfaceNumber</tt> of the interface you
* wish to claim
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if the requested interface does not exist
* \returns LIBUSB_ERROR_BUSY if another program or driver has claimed the
* interface
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns a LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_claim_interface(libusb_device_handle *dev,
int interface_number)
{
int r = 0;
usbi_dbg("interface %d", interface_number);
if (interface_number >= sizeof(dev->claimed_interfaces) * 8)
return LIBUSB_ERROR_INVALID_PARAM;
usbi_mutex_lock(&dev->lock);
if (dev->claimed_interfaces & (1 << interface_number))
goto out;
r = usbi_backend->claim_interface(dev, interface_number);
if (r == 0)
dev->claimed_interfaces |= 1 << interface_number;
out:
usbi_mutex_unlock(&dev->lock);
return r;
}
/** \ingroup dev
* Release an interface previously claimed with libusb_claim_interface(). You
* should release all claimed interfaces before closing a device handle.
*
* This is a blocking function. A SET_INTERFACE control request will be sent
* to the device, resetting interface state to the first alternate setting.
*
* \param dev a device handle
* \param interface_number the <tt>bInterfaceNumber</tt> of the
* previously-claimed interface
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns another LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_release_interface(libusb_device_handle *dev,
int interface_number)
{
int r;
usbi_dbg("interface %d", interface_number);
if (interface_number >= sizeof(dev->claimed_interfaces) * 8)
return LIBUSB_ERROR_INVALID_PARAM;
usbi_mutex_lock(&dev->lock);
if (!(dev->claimed_interfaces & (1 << interface_number))) {
r = LIBUSB_ERROR_NOT_FOUND;
goto out;
}
r = usbi_backend->release_interface(dev, interface_number);
if (r == 0)
dev->claimed_interfaces &= ~(1 << interface_number);
out:
usbi_mutex_unlock(&dev->lock);
return r;
}
/** \ingroup dev
* Activate an alternate setting for an interface. The interface must have
* been previously claimed with libusb_claim_interface().
*
* You should always use this function rather than formulating your own
* SET_INTERFACE control request. This is because the underlying operating
* system needs to know when such changes happen.
*
* This is a blocking function.
*
* \param dev a device handle
* \param interface_number the <tt>bInterfaceNumber</tt> of the
* previously-claimed interface
* \param alternate_setting the <tt>bAlternateSetting</tt> of the alternate
* setting to activate
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if the interface was not claimed, or the
* requested alternate setting does not exist
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns another LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_set_interface_alt_setting(libusb_device_handle *dev,
int interface_number, int alternate_setting)
{
usbi_dbg("interface %d altsetting %d",
interface_number, alternate_setting);
if (interface_number >= sizeof(dev->claimed_interfaces) * 8)
return LIBUSB_ERROR_INVALID_PARAM;
usbi_mutex_lock(&dev->lock);
if (!(dev->claimed_interfaces & (1 << interface_number))) {
usbi_mutex_unlock(&dev->lock);
return LIBUSB_ERROR_NOT_FOUND;
}
usbi_mutex_unlock(&dev->lock);
return usbi_backend->set_interface_altsetting(dev, interface_number,
alternate_setting);
}
/** \ingroup dev
* Clear the halt/stall condition for an endpoint. Endpoints with halt status
* are unable to receive or transmit data until the halt condition is stalled.
*
* You should cancel all pending transfers before attempting to clear the halt
* condition.
*
* This is a blocking function.
*
* \param dev a device handle
* \param endpoint the endpoint to clear halt status
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if the endpoint does not exist
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns another LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_clear_halt(libusb_device_handle *dev,
unsigned char endpoint)
{
usbi_dbg("endpoint %x", endpoint);
return usbi_backend->clear_halt(dev, endpoint);
}
/** \ingroup dev
* Perform a USB port reset to reinitialize a device. The system will attempt
* to restore the previous configuration and alternate settings after the
* reset has completed.
*
* If the reset fails, the descriptors change, or the previous state cannot be
* restored, the device will appear to be disconnected and reconnected. This
* means that the device handle is no longer valid (you should close it) and
* rediscover the device. A return code of LIBUSB_ERROR_NOT_FOUND indicates
* when this is the case.
*
* This is a blocking function which usually incurs a noticeable delay.
*
* \param dev a handle of the device to reset
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if re-enumeration is required, or if the
* device has been disconnected
* \returns another LIBUSB_ERROR code on other failure
*/
int API_EXPORTED libusb_reset_device(libusb_device_handle *dev)
{
usbi_dbg("");
return usbi_backend->reset_device(dev);
}
/** \ingroup dev
* Determine if a kernel driver is active on an interface. If a kernel driver
* is active, you cannot claim the interface, and libusb will be unable to
* perform I/O.
*
* This functionality is not available on Windows.
*
* \param dev a device handle
* \param interface_number the interface to check
* \returns 0 if no kernel driver is active
* \returns 1 if a kernel driver is active
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
* is not available
* \returns another LIBUSB_ERROR code on other failure
* \see libusb_detach_kernel_driver()
*/
int API_EXPORTED libusb_kernel_driver_active(libusb_device_handle *dev,
int interface_number)
{
usbi_dbg("interface %d", interface_number);
if (usbi_backend->kernel_driver_active)
return usbi_backend->kernel_driver_active(dev, interface_number);
else
return LIBUSB_ERROR_NOT_SUPPORTED;
}
/** \ingroup dev
* Detach a kernel driver from an interface. If successful, you will then be
* able to claim the interface and perform I/O.
*
* This functionality is not available on Darwin or Windows.
*
* \param dev a device handle
* \param interface_number the interface to detach the driver from
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
* \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
* is not available
* \returns another LIBUSB_ERROR code on other failure
* \see libusb_kernel_driver_active()
*/
int API_EXPORTED libusb_detach_kernel_driver(libusb_device_handle *dev,
int interface_number)
{
usbi_dbg("interface %d", interface_number);
if (usbi_backend->detach_kernel_driver)
return usbi_backend->detach_kernel_driver(dev, interface_number);
else
return LIBUSB_ERROR_NOT_SUPPORTED;
}
/** \ingroup dev
* Re-attach an interface's kernel driver, which was previously detached
* using libusb_detach_kernel_driver(). This call is only effective on
* Linux and returns LIBUSB_ERROR_NOT_SUPPORTED on all other platforms.
*
* This functionality is not available on Darwin or Windows.
*
* \param dev a device handle
* \param interface_number the interface to attach the driver from
* \returns 0 on success
* \returns LIBUSB_ERROR_NOT_FOUND if no kernel driver was active
* \returns LIBUSB_ERROR_INVALID_PARAM if the interface does not exist
* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
* \returns LIBUSB_ERROR_NOT_SUPPORTED on platforms where the functionality
* is not available
* \returns LIBUSB_ERROR_BUSY if the driver cannot be attached because the
* interface is claimed by a program or driver
* \returns another LIBUSB_ERROR code on other failure
* \see libusb_kernel_driver_active()
*/
int API_EXPORTED libusb_attach_kernel_driver(libusb_device_handle *dev,
int interface_number)
{
usbi_dbg("interface %d", interface_number);
if (usbi_backend->attach_kernel_driver)
return usbi_backend->attach_kernel_driver(dev, interface_number);
else
return LIBUSB_ERROR_NOT_SUPPORTED;
}
/** \ingroup lib
* Set message verbosity.
* - Level 0: no messages ever printed by the library (default)
* - Level 1: error messages are printed to stderr
* - Level 2: warning and error messages are printed to stderr
* - Level 3: informational messages are printed to stdout, warning and error
* messages are printed to stderr
*
* The default level is 0, which means no messages are ever printed. If you
* choose to increase the message verbosity level, ensure that your
* application does not close the stdout/stderr file descriptors.
*
* You are advised to set level 3. libusb is conservative with its message
* logging and most of the time, will only log messages that explain error
* conditions and other oddities. This will help you debug your software.
*
* If the LIBUSB_DEBUG environment variable was set when libusb was
* initialized, this function does nothing: the message verbosity is fixed
* to the value in the environment variable.
*
* If libusb was compiled without any message logging, this function does
* nothing: you'll never get any messages.
*
* If libusb was compiled with verbose debug message logging, this function
* does nothing: you'll always get messages from all levels.
*
* \param ctx the context to operate on, or NULL for the default context
* \param level debug level to set
*/
void API_EXPORTED libusb_set_debug(libusb_context *ctx, int level)
{
USBI_GET_CONTEXT(ctx);
if (!ctx->debug_fixed)
ctx->debug = level;
}
/** \ingroup lib
* Initialize libusb. This function must be called before calling any other
* libusb function.
*
* If you do not provide an output location for a context pointer, a default
* context will be created. If there was already a default context, it will
* be reused (and nothing will be initialized/reinitialized).
*
* \param context Optional output location for context pointer.
* Only valid on return code 0.
* \returns 0 on success, or a LIBUSB_ERROR code on failure
* \see contexts
*/
int API_EXPORTED libusb_init(libusb_context **context)
{
char *dbg = getenv("LIBUSB_DEBUG");
struct libusb_context *ctx;
int r;
usbi_mutex_static_lock(&default_context_lock);
if (!context && usbi_default_context) {
r = 0;
usbi_dbg("reusing default context");
default_context_refcnt++;
usbi_mutex_static_unlock(&default_context_lock);
return 0;
}
ctx = malloc(sizeof(*ctx));
if (!ctx) {
r = LIBUSB_ERROR_NO_MEM;
goto err_unlock;
}
memset(ctx, 0, sizeof(*ctx));
if (dbg) {
ctx->debug = atoi(dbg);
if (ctx->debug)
ctx->debug_fixed = 1;
}
// default context should be initialized before any call to usbi_dbg
if (!usbi_default_context) {
usbi_default_context = ctx;
usbi_dbg("created default context");
}
usbi_dbg("");
if (usbi_backend->init) {
r = usbi_backend->init(ctx);
if (r)
goto err_free_ctx;
}
usbi_mutex_init(&ctx->usb_devs_lock, NULL);
usbi_mutex_init(&ctx->open_devs_lock, NULL);
list_init(&ctx->usb_devs);
list_init(&ctx->open_devs);
r = usbi_io_init(ctx);
if (r < 0) {
if (usbi_backend->exit)
usbi_backend->exit();
goto err_destroy_mutex;
}
if (context) {
*context = ctx;
} else if (!usbi_default_context) {
usbi_dbg("created default context");
usbi_default_context = ctx;
default_context_refcnt++;
}
usbi_mutex_static_unlock(&default_context_lock);
return 0;
err_destroy_mutex:
if (usbi_default_context == ctx)
usbi_default_context = NULL;
usbi_mutex_destroy(&ctx->open_devs_lock);
usbi_mutex_destroy(&ctx->usb_devs_lock);
err_free_ctx:
free(ctx);
err_unlock:
usbi_mutex_static_unlock(&default_context_lock);
return r;
}
/** \ingroup lib
* Deinitialize libusb. Should be called after closing all open devices and
* before your application terminates.
* \param ctx the context to deinitialize, or NULL for the default context
*/
void API_EXPORTED libusb_exit(struct libusb_context *ctx)
{
USBI_GET_CONTEXT(ctx);
usbi_dbg("");
/* if working with default context, only actually do the deinitialization
* if we're the last user */
if (ctx == usbi_default_context) {
usbi_mutex_static_lock(&default_context_lock);
if (--default_context_refcnt > 0) {
usbi_dbg("not destroying default context");
usbi_mutex_static_unlock(&default_context_lock);
return;
}
usbi_dbg("destroying default context");
usbi_default_context = NULL;
usbi_mutex_static_unlock(&default_context_lock);
}
/* a little sanity check. doesn't bother with open_devs locking because
* unless there is an application bug, nobody will be accessing this. */
if (!list_empty(&ctx->open_devs))
usbi_warn(ctx, "application left some devices open");
usbi_io_exit(ctx);
if (usbi_backend->exit)
usbi_backend->exit();
usbi_mutex_destroy(&ctx->open_devs_lock);
usbi_mutex_destroy(&ctx->usb_devs_lock);
free(ctx);
}
void usbi_log_v(struct libusb_context *ctx, enum usbi_log_level level,
const char *function, const char *format, va_list args)
{
FILE *stream = stdout;
const char *prefix;
#ifndef ENABLE_DEBUG_LOGGING
USBI_GET_CONTEXT(ctx);
if (ctx == NULL)
return;
if (!ctx->debug)
return;
if (level == LOG_LEVEL_WARNING && ctx->debug < 2)
return;
if (level == LOG_LEVEL_INFO && ctx->debug < 3)
return;
if (level == LOG_LEVEL_DEBUG && ctx->debug < 4)
return;
#endif
switch (level) {
case LOG_LEVEL_INFO:
prefix = "info";
break;
case LOG_LEVEL_WARNING:
stream = stderr;
prefix = "warning";
break;
case LOG_LEVEL_ERROR:
stream = stderr;
prefix = "error";
break;
case LOG_LEVEL_DEBUG:
stream = stderr;
prefix = "debug";
break;
default:
stream = stderr;
prefix = "unknown";
break;
}
fprintf(stream, "libusb:%s [%s] ", prefix, function);
vfprintf(stream, format, args);
fprintf(stream, "\n");
}
void usbi_log(struct libusb_context *ctx, enum usbi_log_level level,
const char *function, const char *format, ...)
{
va_list args;
va_start (args, format);
usbi_log_v(ctx, level, function, format, args);
va_end (args);
}
/** \ingroup misc
* Returns a constant NULL-terminated string with an English short description
* of the given error code. The caller should never free() the returned pointer
* since it points to a constant string.
* The returned string is encoded in ASCII form and always starts with a
* capital letter and ends without any punctuation.
* Future versions of libusb may return NULL if the library is compiled without
* these messages included (e.g. for embedded systems).
* This function is intended to be used for debugging purposes only.
*
* \param errcode the error code whose description is desired
* \returns a short description of the error code in English, or NULL if the
* error descriptions are unavailable
*/
DEFAULT_VISIBILITY
const char * LIBUSB_CALL libusb_strerror(enum libusb_error error_code)
{
switch (error_code) {
case LIBUSB_SUCCESS:
return "Success";
case LIBUSB_ERROR_IO:
return "Input/output error";
case LIBUSB_ERROR_INVALID_PARAM:
return "Invalid parameter";
case LIBUSB_ERROR_ACCESS:
return "Access denied (insufficient permissions)";
case LIBUSB_ERROR_NO_DEVICE:
return "No such device (it may have been disconnected)";
case LIBUSB_ERROR_NOT_FOUND:
return "Entity not found";
case LIBUSB_ERROR_BUSY:
return "Resource busy";
case LIBUSB_ERROR_TIMEOUT:
return "Operation timed out";
case LIBUSB_ERROR_OVERFLOW:
return "Overflow";
case LIBUSB_ERROR_PIPE:
return "Pipe error";
case LIBUSB_ERROR_INTERRUPTED:
return "System call interrupted (perhaps due to signal)";
case LIBUSB_ERROR_NO_MEM:
return "Insufficient memory";
case LIBUSB_ERROR_NOT_SUPPORTED:
return "Operation not supported or unimplemented on this platform";
case LIBUSB_ERROR_OTHER:
return "Other error";
}
return "Unknown error";
}
/** \ingroup misc
* Fills a libusb_version struct with the full version (major, minor,
* micro, nano) of this library
*/
DEFAULT_VISIBILITY
const struct libusb_version * LIBUSB_CALL libusb_getversion(void)
{
return &libusb_version_internal;
}
