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
  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 */
  47 static struct udev *udev_ctx = NULL;
  48 static int udev_monitor_fd = -1;
  49 static int udev_control_pipe[2] = {-1, -1};
  50 static struct udev_monitor *udev_monitor = NULL;
  51 static pthread_t linux_event_thread;
  52
  53 static void udev_hotplug_event(struct udev_device* udev_dev);
  54 static void *linux_udev_event_thread_main(void *arg);
  55
  56 int linux_udev_start_event_monitor(void)
  57 {
  58         int r;
  59
  60         assert(udev_ctx == NULL);
  61         udev_ctx = udev_new();
  62         if (!udev_ctx) {
  63                 usbi_err(NULL, "could not create udev context");
  64                 return LIBUSB_ERROR_OTHER;
  65         }
  66
  67         udev_monitor = udev_monitor_new_from_netlink(udev_ctx, "udev");
  68         if (!udev_monitor) {
  69                 usbi_err(NULL, "could not initialize udev monitor");
  70                 goto err_free_ctx;
  71         }
  72
  73         r = udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "usb", 0);
  74         if (r) {
  75                 usbi_err(NULL, "could not initialize udev monitor filter for \"usb\" subsystem");
  76                 goto err_free_monitor;
  77         }
  78
  79         if (udev_monitor_enable_receiving(udev_monitor)) {
  80                 usbi_err(NULL, "failed to enable the udev monitor");
  81                 goto err_free_monitor;
  82         }
  83
  84         udev_monitor_fd = udev_monitor_get_fd(udev_monitor);
  85
  86         /* Some older versions of udev are not non-blocking by default,
  87          * so make sure this is set */
  88         r = fcntl(udev_monitor_fd, F_GETFL);
  89         if (r == -1) {
  90                 usbi_err(NULL, "getting udev monitor fd flags (%d)", errno);
  91                 goto err_free_monitor;
  92         }
  93         r = fcntl(udev_monitor_fd, F_SETFL, r | O_NONBLOCK);
  94         if (r) {
  95                 usbi_err(NULL, "setting udev monitor fd flags (%d)", errno);
  96                 goto err_free_monitor;
  97         }
  98
  99         r = usbi_pipe(udev_control_pipe);
 100         if (r) {
 101                 usbi_err(NULL, "could not create udev control pipe");
 102                 goto err_free_monitor;
 103         }
 104
 105         r = pthread_create(&linux_event_thread, NULL, linux_udev_event_thread_main, NULL);
 106         if (r) {
 107                 usbi_err(NULL, "creating hotplug event thread (%d)", r);
 108                 goto err_close_pipe;
 109         }
 110
 111         return LIBUSB_SUCCESS;
 112
 113 err_close_pipe:
 114         close(udev_control_pipe[0]);
 115         close(udev_control_pipe[1]);
 116 err_free_monitor:
 117         udev_monitor_unref(udev_monitor);
 118         udev_monitor = NULL;
 119         udev_monitor_fd = -1;
 120 err_free_ctx:
 121         udev_unref(udev_ctx);
 122         udev_ctx = NULL;
 123         return LIBUSB_ERROR_OTHER;
 124 }
 125
 126 int linux_udev_stop_event_monitor(void)
 127 {
 128         char dummy = 1;
 129         int r;
 130
 131         assert(udev_ctx != NULL);
 132         assert(udev_monitor != NULL);
 133         assert(udev_monitor_fd != -1);
 134
 135         /* Write some dummy data to the control pipe and
 136          * wait for the thread to exit */
 137         r = usbi_write(udev_control_pipe[1], &dummy, sizeof(dummy));
 138         if (r <= 0) {
 139                 usbi_warn(NULL, "udev control pipe signal failed");
 140         }
 141         pthread_join(linux_event_thread, NULL);
 142
 143         /* Release the udev monitor */
 144         udev_monitor_unref(udev_monitor);
 145         udev_monitor = NULL;
 146         udev_monitor_fd = -1;
 147
 148         /* Clean up the udev context */
 149         udev_unref(udev_ctx);
 150         udev_ctx = NULL;
 151
 152         /* close and reset control pipe */
 153         close(udev_control_pipe[0]);
 154         close(udev_control_pipe[1]);
 155         udev_control_pipe[0] = -1;
 156         udev_control_pipe[1] = -1;
 157
 158         return LIBUSB_SUCCESS;
 159 }
 160
 161 static void *linux_udev_event_thread_main(void *arg)
 162 {
 163         char dummy;
 164         int r;
 165         struct udev_device* udev_dev;
 166         struct pollfd fds[] = {
 167                 {.fd = udev_control_pipe[0],
 168                  .events = POLLIN},
 169                 {.fd = udev_monitor_fd,
 170                  .events = POLLIN},
 171         };
 172
 173         usbi_dbg("udev event thread entering.");
 174
 175         while (poll(fds, 2, -1) >= 0) {
 176                 if (fds[0].revents & POLLIN) {
 177                         /* activity on control pipe, read the byte and exit */
 178                         r = usbi_read(udev_control_pipe[0], &dummy, sizeof(dummy));
 179                         if (r <= 0) {
 180                                 usbi_warn(NULL, "udev control pipe read failed");
 181                         }
 182                         break;
 183                 }
 184                 if (fds[1].revents & POLLIN) {
 185                         usbi_mutex_static_lock(&linux_hotplug_lock);
 186                         udev_dev = udev_monitor_receive_device(udev_monitor);
 187                         if (udev_dev)
 188                                 udev_hotplug_event(udev_dev);
 189                         usbi_mutex_static_unlock(&linux_hotplug_lock);
 190                 }
 191         }
 192
 193         usbi_dbg("udev event thread exiting");
 194
 195         return NULL;
 196 }
 197
 198 static int udev_device_info(struct libusb_context *ctx, int detached,
 199                             struct udev_device *udev_dev, uint8_t *busnum,
 200                             uint8_t *devaddr, const char **sys_name) {
 201         const char *dev_node;
 202
 203         dev_node = udev_device_get_devnode(udev_dev);
 204         if (!dev_node) {
 205                 return LIBUSB_ERROR_OTHER;
 206         }
 207
 208         *sys_name = udev_device_get_sysname(udev_dev);
 209         if (!*sys_name) {
 210                 return LIBUSB_ERROR_OTHER;
 211         }
 212
 213         return linux_get_device_address(ctx, detached, busnum, devaddr,
 214                                         dev_node, *sys_name);
 215 }
 216
 217 static void udev_hotplug_event(struct udev_device* udev_dev)
 218 {
 219         const char* udev_action;
 220         const char* sys_name = NULL;
 221         uint8_t busnum = 0, devaddr = 0;
 222         int detached;
 223         int r;
 224
 225         do {
 226                 udev_action = udev_device_get_action(udev_dev);
 227                 if (!udev_action) {
 228                         break;
 229                 }
 230
 231                 detached = !strncmp(udev_action, "remove", 6);
 232
 233                 r = udev_device_info(NULL, detached, udev_dev, &busnum, &devaddr, &sys_name);
 234                 if (LIBUSB_SUCCESS != r) {
 235                         break;
 236                 }
 237
 238                 usbi_dbg("udev hotplug event. action: %s.", udev_action);
 239
 240                 if (strncmp(udev_action, "add", 3) == 0) {
 241                         linux_hotplug_enumerate(busnum, devaddr, sys_name);
 242                 } else if (detached) {
 243                         linux_device_disconnected(busnum, devaddr, sys_name);
 244                 } else {
 245                         usbi_err(NULL, "ignoring udev action %s", udev_action);
 246                 }
 247         } while (0);
 248
 249         udev_device_unref(udev_dev);
 250 }
 251
 252 int linux_udev_scan_devices(struct libusb_context *ctx)
 253 {
 254         struct udev_enumerate *enumerator;
 255         struct udev_list_entry *devices, *entry;
 256         struct udev_device *udev_dev;
 257         const char *sys_name;
 258         int r;
 259
 260         assert(udev_ctx != NULL);
 261
 262         enumerator = udev_enumerate_new(udev_ctx);
 263         if (NULL == enumerator) {
 264                 usbi_err(ctx, "error creating udev enumerator");
 265                 return LIBUSB_ERROR_OTHER;
 266         }
 267
 268         udev_enumerate_add_match_subsystem(enumerator, "usb");
 269         udev_enumerate_scan_devices(enumerator);
 270         devices = udev_enumerate_get_list_entry(enumerator);
 271
 272         udev_list_entry_foreach(entry, devices) {
 273                 const char *path = udev_list_entry_get_name(entry);
 274                 uint8_t busnum = 0, devaddr = 0;
 275
 276                 udev_dev = udev_device_new_from_syspath(udev_ctx, path);
 277
 278                 r = udev_device_info(ctx, 0, udev_dev, &busnum, &devaddr, &sys_name);
 279                 if (r) {
 280                         udev_device_unref(udev_dev);
 281                         continue;
 282                 }
 283
 284                 linux_enumerate_device(ctx, busnum, devaddr, sys_name);
 285                 udev_device_unref(udev_dev);
 286         }
 287
 288         udev_enumerate_unref(enumerator);
 289
 290         return LIBUSB_SUCCESS;
 291 }
 292
 293 void linux_udev_hotplug_poll(void)
 294 {
 295         struct udev_device* udev_dev;
 296
 297         usbi_mutex_static_lock(&linux_hotplug_lock);
 298         do {
 299                 udev_dev = udev_monitor_receive_device(udev_monitor);
 300                 if (udev_dev) {
 301                         usbi_dbg("Handling hotplug event from hotplug_poll");
 302                         udev_hotplug_event(udev_dev);
 303                 }
 304         } while (udev_dev);
 305         usbi_mutex_static_unlock(&linux_hotplug_lock);
 306 }