udev.c

   1 /*
   2  * udev.c
   3  *
   4  * Userspace devfs
   5  *
   6  * Copyright (C) 2003,2004 Greg Kroah-Hartman <greg@kroah.com>
   7  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
   8  *
   9  *      This program is free software; you can redistribute it and/or modify it
  10  *      under the terms of the GNU General Public License as published by the
  11  *      Free Software Foundation version 2 of the License.
  12  *
  13  *      This program is distributed in the hope that it will be useful, but
  14  *      WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  *      General Public License for more details.
  17  *
  18  *      You should have received a copy of the GNU General Public License along
  19  *      with this program; if not, write to the Free Software Foundation, Inc.,
  20  *      675 Mass Ave, Cambridge, MA 02139, USA.
  21  *
  22  */
  23
  24 #include <stdio.h>
  25 #include <stddef.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <fcntl.h>
  29 #include <ctype.h>
  30 #include <errno.h>
  31 #include <signal.h>
  32 #include <unistd.h>
  33
  34 #include "libsysfs/sysfs/libsysfs.h"
  35 #include "udev.h"
  36 #include "udev_utils.h"
  37 #include "udev_sysfs.h"
  38 #include "udev_version.h"
  39 #include "namedev.h"
  40 #include "logging.h"
  41
  42
  43 #ifdef LOG
  44 void log_message(int level, const char *format, ...)
  45 {
  46         va_list args;
  47
  48         if (!udev_log)
  49                 return;
  50
  51         va_start(args, format);
  52         vsyslog(level, format, args);
  53         va_end(args);
  54 }
  55 #endif
  56
  57 /* decide if we should manage the whole hotplug event
  58  * for now look if the kernel calls udevsend instead of /sbin/hotplug
  59  */
  60 static int manage_hotplug_event(void) {
  61         char helper[256];
  62         int fd;
  63         int len;
  64
  65         /* don't handle hotplug.d if we are called directly */
  66         if (!getenv("UDEVD_EVENT"))
  67                 return 0;
  68
  69         fd = open("/proc/sys/kernel/hotplug", O_RDONLY);
  70         if (fd < 0)
  71                 return 0;
  72
  73         len = read(fd, helper, 256);
  74         close(fd);
  75
  76         if (len < 0)
  77                 return 0;
  78         helper[len] = '\0';
  79
  80         if (strstr(helper, "udevsend"))
  81                 return 1;
  82
  83         return 0;
  84 }
  85
  86 static void asmlinkage sig_handler(int signum)
  87 {
  88         switch (signum) {
  89                 case SIGALRM:
  90                         exit(1);
  91                 case SIGINT:
  92                 case SIGTERM:
  93                         exit(20 + signum);
  94         }
  95 }
  96
  97 int main(int argc, char *argv[], char *envp[])
  98 {
  99         struct sigaction act;
 100         struct sysfs_class_device *class_dev;
 101         struct sysfs_device *devices_dev;
 102         struct udevice udev;
 103         char path[SYSFS_PATH_MAX];
 104         const char *error;
 105         const char *action;
 106         const char *devpath;
 107         const char *subsystem;
 108         int managed_event;
 109         int retval = -EINVAL;
 110
 111         if (argc == 2 && strcmp(argv[1], "-V") == 0) {
 112                 printf("%s\n", UDEV_VERSION);
 113                 exit(0);
 114         }
 115
 116         logging_init("udev");
 117         dbg("version %s", UDEV_VERSION);
 118
 119         udev_init_config();
 120
 121         /* set signal handlers */
 122         memset(&act, 0x00, sizeof(act));
 123         act.sa_handler = (void (*) (int))sig_handler;
 124         sigemptyset (&act.sa_mask);
 125         act.sa_flags = 0;
 126         sigaction(SIGALRM, &act, NULL);
 127         sigaction(SIGINT, &act, NULL);
 128         sigaction(SIGTERM, &act, NULL);
 129
 130         /* trigger timeout to prevent hanging processes */
 131         alarm(ALARM_TIMEOUT);
 132
 133         if (strstr(argv[0], "udevstart") || (argc == 2 && strstr(argv[1], "udevstart"))) {
 134                 dbg("udevstart");
 135
 136                 /* disable all logging, as it's much too slow on some facilities */
 137                 udev_log = 0;
 138
 139                 namedev_init();
 140                 retval = udev_start();
 141                 goto exit;
 142         }
 143
 144         /* let the executed programs know if we handle the whole hotplug event */
 145         managed_event = manage_hotplug_event();
 146         if (managed_event)
 147                 setenv("MANAGED_EVENT", "1", 1);
 148
 149         action = getenv("ACTION");
 150         devpath = getenv("DEVPATH");
 151         subsystem = getenv("SUBSYSTEM");
 152         /* older kernels passed the SUBSYSTEM only as argument */
 153         if (!subsystem && argc == 2)
 154                 subsystem = argv[1];
 155         udev_init_device(&udev, devpath, subsystem);
 156
 157         if (!action) {
 158                 dbg("no action");
 159                 goto hotplug;
 160         }
 161
 162         if (!subsystem) {
 163                 dbg("no subsystem");
 164                 goto hotplug;
 165         }
 166
 167         if (!devpath) {
 168                 dbg("no devpath");
 169                 goto hotplug;
 170         }
 171
 172         /* export logging flag, as called scripts may want to do the same as udev */
 173         if (udev_log)
 174                 setenv("UDEV_LOG", "1", 1);
 175
 176         if ((strncmp(devpath, "/block/", 7) == 0) || (strncmp(devpath, "/class/", 7) == 0)) {
 177                 if (strcmp(action, "add") == 0) {
 178                         /* wait for sysfs and possibly add node */
 179                         dbg("udev add");
 180
 181                         /* skip subsystems without "dev", but handle net devices */
 182                         if (udev.type != 'n' && subsystem_expect_no_dev(udev.subsystem)) {
 183                                 dbg("don't care about '%s' devices", udev.subsystem);
 184                                 goto hotplug;
 185                         }
 186
 187                         snprintf(path, SYSFS_PATH_MAX, "%s%s", sysfs_path, udev.devpath);
 188                         class_dev = wait_class_device_open(path);
 189                         if (class_dev == NULL) {
 190                                 dbg ("open class device failed");
 191                                 goto hotplug;
 192                         }
 193                         dbg("opened class_dev->name='%s'", class_dev->name);
 194
 195                         wait_for_class_device(class_dev, &error);
 196
 197                         /* init rules */
 198                         namedev_init();
 199
 200                         /* name, create node, store in db */
 201                         retval = udev_add_device(&udev, class_dev);
 202
 203                         sysfs_close_class_device(class_dev);
 204                 } else if (strcmp(action, "remove") == 0) {
 205                         /* possibly remove a node */
 206                         dbg("udev remove");
 207
 208                         /* skip subsystems without "dev" */
 209                         if (subsystem_expect_no_dev(udev.subsystem)) {
 210                                 dbg("don't care about '%s' devices", udev.subsystem);
 211                                 goto hotplug;
 212                         }
 213
 214                         /* get node from db, remove db-entry, delete created node */
 215                         retval = udev_remove_device(&udev);
 216                 }
 217
 218                 /* run dev.d/ scripts if we created/deleted a node or changed a netif name */
 219                 if (udev.devname[0] != '\0') {
 220                         setenv("DEVNAME", udev.devname, 1);
 221                         if (udev_dev_d)
 222                                 udev_multiplex_directory(&udev, DEVD_DIR, DEVD_SUFFIX);
 223                 }
 224         } else if ((strncmp(devpath, "/devices/", 9) == 0)) {
 225                 if (strcmp(action, "add") == 0) {
 226                         /* wait for sysfs */
 227                         dbg("devices add");
 228
 229                         snprintf(path, SYSFS_PATH_MAX, "%s%s", sysfs_path, devpath);
 230                         devices_dev = wait_devices_device_open(path);
 231                         if (!devices_dev) {
 232                                 dbg("devices device unavailable (probably remove has beaten us)");
 233                                 goto hotplug;
 234                         }
 235                         dbg("devices device opened '%s'", path);
 236
 237                         wait_for_devices_device(devices_dev, &error);
 238
 239                         sysfs_close_device(devices_dev);
 240                 } else if (strcmp(action, "remove") == 0) {
 241                         dbg("devices remove");
 242                 }
 243         } else {
 244                 dbg("unhandled");
 245         }
 246
 247 hotplug:
 248         if (udev_hotplug_d && managed_event)
 249                 udev_multiplex_directory(&udev, HOTPLUGD_DIR, HOTPLUG_SUFFIX);
 250
 251 exit:
 252         logging_close();
 253         return retval;
 254 }