libusb/os/linux_udev.c

   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 #include <ctype.h>
  25 #include <dirent.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <poll.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/ioctl.h>
  33 #include <sys/stat.h>
  34 #include <sys/types.h>
  35 #include <sys/utsname.h>
  36 #include <sys/socket.h>
  37 #include <unistd.h>
  38 #include <libudev.h>
  39
  40 #include "libusb.h"
  41 #include "libusbi.h"
  42 #include "linux_usbfs.h"
  43
  44 /* udev context */
  45 static struct udev *udev_ctx = NULL;
  46 static int udev_monitor_fd = -1;
  47 static struct udev_monitor *udev_monitor = NULL;
  48 static pthread_t linux_event_thread;
  49
  50 static void udev_hotplug_event(void);
  51 static void *linux_udev_event_thread_main(void *arg);
  52
  53 int linux_udev_start_event_monitor(void)
  54 {
  55         int r;
  56
  57         if (NULL == udev_ctx) {
  58                 udev_ctx = udev_new();
  59                 if (!udev_ctx) {
  60                         return LIBUSB_ERROR_OTHER;
  61                 }
  62         }
  63
  64         udev_monitor = udev_monitor_new_from_netlink(udev_ctx, "udev");
  65         if (!udev_monitor) {
  66                 usbi_err(NULL, "could not initialize udev monitor");
  67                 return LIBUSB_ERROR_OTHER;
  68         }
  69
  70         r = udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "usb", 0);
  71         if (r) {
  72                 usbi_err(NULL, "could not initialize udev monitor filter for \"usb\" subsystem");
  73                 return LIBUSB_ERROR_OTHER;
  74         }
  75
  76         if (udev_monitor_enable_receiving(udev_monitor)) {
  77                 usbi_err(NULL, "failed to enable the udev monitor");
  78                 return LIBUSB_ERROR_OTHER;
  79         }
  80
  81         udev_monitor_fd = udev_monitor_get_fd(udev_monitor);
  82
  83         pthread_create(&linux_event_thread, NULL, linux_udev_event_thread_main, NULL);
  84
  85         return LIBUSB_SUCCESS;
  86 }
  87
  88 int linux_udev_stop_event_monitor(void)
  89 {
  90         if (-1 == udev_monitor_fd) {
  91                 /* this should never happen */
  92                 return LIBUSB_ERROR_OTHER;
  93         }
  94
  95         /* Cancel the event thread. This is the only way to garauntee the thread
  96            exits since closing the monitor fd won't necessarily cause poll
  97            to return. */
  98         pthread_cancel(linux_event_thread);
  99
 100         /* Release the udev monitor */
 101         udev_monitor_unref(udev_monitor);
 102         udev_monitor = NULL;
 103         udev_monitor_fd = -1;
 104
 105         /* Clean up the udev context */
 106         udev_unref(udev_ctx);
 107         udev_ctx = NULL;
 108
 109         return LIBUSB_SUCCESS;
 110 }
 111
 112 static void *linux_udev_event_thread_main(void *arg)
 113 {
 114         struct pollfd fds = {.fd = udev_monitor_fd,
 115                              .events = POLLIN};
 116
 117         usbi_dbg("udev event thread entering.");
 118
 119         while (1 == poll(&fds, 1, -1)) {
 120                 if (NULL == udev_monitor || POLLIN != fds.revents) {
 121                         break;
 122                 }
 123
 124                 udev_hotplug_event();
 125         }
 126
 127         usbi_dbg("udev event thread exiting");
 128
 129         return NULL;
 130 }
 131
 132 static int udev_device_info(struct libusb_context *ctx, int detached,
 133                             struct udev_device *udev_dev, uint8_t *busnum,
 134                             uint8_t *devaddr, const char **sys_name) {
 135         const char *dev_node;
 136
 137         dev_node = udev_device_get_devnode(udev_dev);
 138         if (!dev_node) {
 139                 return LIBUSB_ERROR_OTHER;
 140         }
 141
 142         *sys_name = udev_device_get_sysname(udev_dev);
 143         if (!*sys_name) {
 144                 return LIBUSB_ERROR_OTHER;
 145         }
 146
 147         return linux_get_device_address(ctx, detached, busnum, devaddr,
 148                                         dev_node, *sys_name);
 149 }
 150
 151 static void udev_hotplug_event(void)
 152 {
 153         struct udev_device* udev_dev;
 154         const char* udev_action;
 155         const char* sys_name = NULL;
 156         uint8_t busnum = 0, devaddr = 0;
 157         int detached;
 158         int r;
 159
 160         if (NULL == udev_monitor) {
 161                 return;
 162         }
 163
 164         do {
 165                 udev_dev = udev_monitor_receive_device(udev_monitor);
 166                 if (!udev_dev) {
 167                         usbi_err(NULL, "failed to read data from udev monitor socket.");
 168                         return;
 169                 }
 170
 171                 udev_action = udev_device_get_action(udev_dev);
 172                 if (!udev_action) {
 173                         break;
 174                 }
 175
 176                 detached = !strncmp(udev_action, "remove", 6);
 177
 178                 r = udev_device_info(NULL, detached, udev_dev, &busnum, &devaddr, &sys_name);
 179                 if (LIBUSB_SUCCESS != r) {
 180                         break;
 181                 }
 182
 183                 usbi_dbg("udev hotplug event. action: %s.", udev_action);
 184
 185                 if (strncmp(udev_action, "add", 3) == 0) {
 186                         linux_hotplug_enumerate(busnum, devaddr, sys_name);
 187                 } else if (detached) {
 188                         linux_hotplug_disconnected(busnum, devaddr, sys_name);
 189                 } else {
 190                         usbi_err(NULL, "ignoring udev action %s", udev_action);
 191                 }
 192         } while (0);
 193
 194         udev_device_unref(udev_dev);
 195 }
 196
 197 int linux_udev_scan_devices(struct libusb_context *ctx)
 198 {
 199         struct udev_enumerate *enumerator;
 200         struct udev_list_entry *devices, *entry;
 201         struct udev_device *udev_dev;
 202         const char *sys_name;
 203         int r;
 204
 205         if (NULL == udev_ctx) {
 206                 udev_ctx = udev_new();
 207                 if (!udev_ctx) {
 208                         return LIBUSB_ERROR_OTHER;
 209                 }
 210         }
 211
 212         enumerator = udev_enumerate_new(udev_ctx);
 213         if (NULL == enumerator) {
 214                 usbi_err(ctx, "error creating udev enumerator");
 215                 return LIBUSB_ERROR_OTHER;
 216         }
 217
 218         udev_enumerate_add_match_subsystem(enumerator, "usb");
 219         udev_enumerate_scan_devices(enumerator);
 220         devices = udev_enumerate_get_list_entry(enumerator);
 221
 222         udev_list_entry_foreach(entry, devices) {
 223                 const char *path = udev_list_entry_get_name(entry);
 224                 uint8_t busnum = 0, devaddr = 0;
 225
 226                 udev_dev = udev_device_new_from_syspath(udev_ctx, path);
 227
 228                 r = udev_device_info(ctx, 0, udev_dev, &busnum, &devaddr, &sys_name);
 229                 if (r) {
 230                         udev_device_unref(udev_dev);
 231                         continue;
 232                 }
 233
 234                 linux_enumerate_device(ctx, busnum, devaddr, sys_name);
 235                 udev_device_unref(udev_dev);
 236         }
 237
 238         udev_enumerate_unref(enumerator);
 239
 240         return LIBUSB_SUCCESS;
 241 }