linux_udev.c revision ca12bfac764ba476d6cd062bf1dde12cc64c3f40 
1/* -*- Mode: C; c-basic-offset:8 ; indent-tabs-mode:t -*- */
2/*
3 * Linux usbfs backend for libusb
4 * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
5 * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
6 * Copyright (c) 2012-2013 Nathan Hjelm <hjelmn@mac.com>
7 *
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include "config.h"
24
25#include <assert.h>
26#include <ctype.h>
27#include <dirent.h>
28#include <errno.h>
29#include <fcntl.h>
30#include <poll.h>
31#include <stdio.h>
32#include <stdlib.h>
33#include <string.h>
34#include <sys/ioctl.h>
35#include <sys/stat.h>
36#include <sys/types.h>
37#include <sys/utsname.h>
38#include <sys/socket.h>
39#include <unistd.h>
40#include <libudev.h>
41
42#include "libusb.h"
43#include "libusbi.h"
44#include "linux_usbfs.h"
45
46/* udev context */
47static struct udev *udev_ctx = NULL;
48static int udev_monitor_fd = -1;
49static struct udev_monitor *udev_monitor = NULL;
50static pthread_t linux_event_thread;
51
52static void udev_hotplug_event(struct udev_device* udev_dev);
53static void *linux_udev_event_thread_main(void *arg);
54
55int linux_udev_start_event_monitor(void)
56{
57	int r;
58
59	assert(udev_ctx == NULL);
60	udev_ctx = udev_new();
61	if (!udev_ctx) {
62		usbi_err(NULL, "could not create udev context");
63		return LIBUSB_ERROR_OTHER;
64	}
65
66	udev_monitor = udev_monitor_new_from_netlink(udev_ctx, "udev");
67	if (!udev_monitor) {
68		usbi_err(NULL, "could not initialize udev monitor");
69		goto err_free_ctx;
70	}
71
72	r = udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "usb", 0);
73	if (r) {
74		usbi_err(NULL, "could not initialize udev monitor filter for \"usb\" subsystem");
75		goto err_free_monitor;
76	}
77
78	if (udev_monitor_enable_receiving(udev_monitor)) {
79		usbi_err(NULL, "failed to enable the udev monitor");
80		goto err_free_monitor;
81	}
82
83	udev_monitor_fd = udev_monitor_get_fd(udev_monitor);
84
85	/* Some older versions of udev are not non-blocking by default,
86	 * so make sure this is set */
87	r = fcntl(udev_monitor_fd, F_GETFL);
88	if (r == -1) {
89		usbi_err(NULL, "getting udev monitor fd flags (%d)", errno);
90		goto err_free_monitor;
91	}
92	r = fcntl(udev_monitor_fd, F_SETFL, r | O_NONBLOCK);
93	if (r) {
94		usbi_err(NULL, "setting udev monitor fd flags (%d)", errno);
95		goto err_free_monitor;
96	}
97
98	r = pthread_create(&linux_event_thread, NULL, linux_udev_event_thread_main, NULL);
99	if (r) {
100		usbi_err(NULL, "creating hotplug event thread (%d)", r);
101		goto err_free_monitor;
102	}
103
104	return LIBUSB_SUCCESS;
105
106err_free_monitor:
107	udev_monitor_unref(udev_monitor);
108	udev_monitor = NULL;
109	udev_monitor_fd = -1;
110err_free_ctx:
111	udev_unref(udev_ctx);
112	udev_ctx = NULL;
113	return LIBUSB_ERROR_OTHER;
114}
115
116int linux_udev_stop_event_monitor(void)
117{
118	assert(udev_ctx != NULL);
119	assert(udev_monitor != NULL);
120	assert(udev_monitor_fd != -1);
121
122	/* Cancel the event thread. This is the only way to guarantee the
123	   thread exits since closing the monitor fd won't necessarily cause
124	   poll to return. */
125	pthread_cancel(linux_event_thread);
126	pthread_join(linux_event_thread, NULL);
127
128	/* Release the udev monitor */
129	udev_monitor_unref(udev_monitor);
130	udev_monitor = NULL;
131	udev_monitor_fd = -1;
132
133	/* Clean up the udev context */
134	udev_unref(udev_ctx);
135	udev_ctx = NULL;
136
137	return LIBUSB_SUCCESS;
138}
139
140static void *linux_udev_event_thread_main(void *arg)
141{
142	struct udev_device* udev_dev;
143	struct pollfd fds = {.fd = udev_monitor_fd,
144			     .events = POLLIN};
145
146	usbi_dbg("udev event thread entering.");
147
148	while (1 == poll(&fds, 1, -1)) {
149		if (NULL == udev_monitor || POLLIN != fds.revents) {
150			break;
151		}
152
153		usbi_mutex_static_lock(&linux_hotplug_lock);
154		udev_dev = udev_monitor_receive_device(udev_monitor);
155		if (udev_dev)
156			udev_hotplug_event(udev_dev);
157		usbi_mutex_static_unlock(&linux_hotplug_lock);
158	}
159
160	usbi_dbg("udev event thread exiting");
161
162	return NULL;
163}
164
165static int udev_device_info(struct libusb_context *ctx, int detached,
166			    struct udev_device *udev_dev, uint8_t *busnum,
167			    uint8_t *devaddr, const char **sys_name) {
168	const char *dev_node;
169
170	dev_node = udev_device_get_devnode(udev_dev);
171	if (!dev_node) {
172		return LIBUSB_ERROR_OTHER;
173	}
174
175	*sys_name = udev_device_get_sysname(udev_dev);
176	if (!*sys_name) {
177		return LIBUSB_ERROR_OTHER;
178	}
179
180	return linux_get_device_address(ctx, detached, busnum, devaddr,
181					dev_node, *sys_name);
182}
183
184static void udev_hotplug_event(struct udev_device* udev_dev)
185{
186	const char* udev_action;
187	const char* sys_name = NULL;
188	uint8_t busnum = 0, devaddr = 0;
189	int detached;
190	int r;
191
192	do {
193		udev_action = udev_device_get_action(udev_dev);
194		if (!udev_action) {
195			break;
196		}
197
198		detached = !strncmp(udev_action, "remove", 6);
199
200		r = udev_device_info(NULL, detached, udev_dev, &busnum, &devaddr, &sys_name);
201		if (LIBUSB_SUCCESS != r) {
202			break;
203		}
204
205		usbi_dbg("udev hotplug event. action: %s.", udev_action);
206
207		if (strncmp(udev_action, "add", 3) == 0) {
208			linux_hotplug_enumerate(busnum, devaddr, sys_name);
209		} else if (detached) {
210			linux_hotplug_disconnected(busnum, devaddr, sys_name);
211		} else {
212			usbi_err(NULL, "ignoring udev action %s", udev_action);
213		}
214	} while (0);
215
216	udev_device_unref(udev_dev);
217}
218
219int linux_udev_scan_devices(struct libusb_context *ctx)
220{
221	struct udev_enumerate *enumerator;
222	struct udev_list_entry *devices, *entry;
223	struct udev_device *udev_dev;
224	const char *sys_name;
225	int r;
226
227	assert(udev_ctx != NULL);
228
229	enumerator = udev_enumerate_new(udev_ctx);
230	if (NULL == enumerator) {
231		usbi_err(ctx, "error creating udev enumerator");
232		return LIBUSB_ERROR_OTHER;
233	}
234
235	udev_enumerate_add_match_subsystem(enumerator, "usb");
236	udev_enumerate_scan_devices(enumerator);
237	devices = udev_enumerate_get_list_entry(enumerator);
238
239	udev_list_entry_foreach(entry, devices) {
240		const char *path = udev_list_entry_get_name(entry);
241		uint8_t busnum = 0, devaddr = 0;
242
243		udev_dev = udev_device_new_from_syspath(udev_ctx, path);
244
245		r = udev_device_info(ctx, 0, udev_dev, &busnum, &devaddr, &sys_name);
246		if (r) {
247			udev_device_unref(udev_dev);
248			continue;
249		}
250
251		linux_enumerate_device(ctx, busnum, devaddr, sys_name);
252		udev_device_unref(udev_dev);
253	}
254
255	udev_enumerate_unref(enumerator);
256
257	return LIBUSB_SUCCESS;
258}
259
260void linux_udev_hotplug_poll(void)
261{
262	struct udev_device* udev_dev;
263
264	usbi_mutex_static_lock(&linux_hotplug_lock);
265	do {
266		udev_dev = udev_monitor_receive_device(udev_monitor);
267		if (udev_dev) {
268			usbi_dbg("Handling hotplug event from hotplug_poll");
269			udev_hotplug_event(udev_dev);
270		}
271	} while (udev_dev);
272	usbi_mutex_static_unlock(&linux_hotplug_lock);
273}
274