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_libc_wrapper.h"
  36 #include "udev.h"
  37 #include "udev_utils.h"
  38 #include "udev_sysfs.h"
  39 #include "udev_version.h"
  40 #include "udev_rules.h"
  41 #include "logging.h"
  42
  43 #ifdef USE_LOG
  44 void log_message(int priority, const char *format, ...)
  45 {
  46         va_list args;
  47
  48         if (priority > udev_log_priority)
  49                 return;
  50
  51         va_start(args, format);
  52         vsyslog(priority, format, args);
  53         va_end(args);
  54 }
  55 #endif
  56
  57 /* Decide if we should manage the whole uevent, including multiplexing
  58  * of the hotplug directories.
  59  * For now look if the kernel calls udevsend instead of /sbin/hotplug,
  60  * or the uevent-helper in /proc/sys/kernel/hotplug is empty.
  61  */
  62 static int manage_hotplug_event(void) {
  63         char helper[256];
  64         int fd;
  65         int len;
  66
  67         /* don't handle hotplug.d if we are called directly */
  68         if (!getenv("UDEVD_EVENT"))
  69                 return 0;
  70
  71         fd = open("/proc/sys/kernel/hotplug", O_RDONLY);
  72         if (fd < 0)
  73                 return 0;
  74
  75         len = read(fd, helper, sizeof(helper)-1);
  76         close(fd);
  77
  78         if (len < 0)
  79                 return 0;
  80         helper[len] = '\0';
  81
  82         if (helper[0] == '\0' || helper[0] == '\n')
  83                 return 1;
  84         if (strstr(helper, "udevsend"))
  85                 return 1;
  86
  87         return 0;
  88 }
  89
  90 static void asmlinkage sig_handler(int signum)
  91 {
  92         switch (signum) {
  93                 case SIGALRM:
  94                         exit(1);
  95                 case SIGINT:
  96                 case SIGTERM:
  97                         exit(20 + signum);
  98         }
  99 }
 100
 101 int main(int argc, char *argv[], char *envp[])
 102 {
 103         struct sysfs_class_device *class_dev;
 104         struct sysfs_device *devices_dev;
 105         struct udevice udev;
 106         char path[PATH_SIZE];
 107         const char *error;
 108         const char *action;
 109         const char *devpath;
 110         const char *subsystem;
 111         int managed_event;
 112         struct sigaction act;
 113         int retval = -EINVAL;
 114
 115         if (argc == 2 && strcmp(argv[1], "-V") == 0) {
 116                 printf("%s\n", UDEV_VERSION);
 117                 exit(0);
 118         }
 119
 120         logging_init("udev");
 121         udev_init_config();
 122         dbg("version %s", UDEV_VERSION);
 123
 124         /* set signal handlers */
 125         memset(&act, 0x00, sizeof(act));
 126         act.sa_handler = (void (*)(int)) sig_handler;
 127         sigemptyset (&act.sa_mask);
 128         act.sa_flags = 0;
 129         sigaction(SIGALRM, &act, NULL);
 130         sigaction(SIGINT, &act, NULL);
 131         sigaction(SIGTERM, &act, NULL);
 132
 133         /* trigger timeout to prevent hanging processes */
 134         alarm(ALARM_TIMEOUT);
 135
 136         /* let the executed programs know if we handle the whole hotplug event */
 137         managed_event = manage_hotplug_event();
 138         if (managed_event)
 139                 setenv("MANAGED_EVENT", "1", 1);
 140
 141         action = getenv("ACTION");
 142         devpath = getenv("DEVPATH");
 143         subsystem = getenv("SUBSYSTEM");
 144         /* older kernels passed the SUBSYSTEM only as argument */
 145         if (!subsystem && argc == 2)
 146                 subsystem = argv[1];
 147
 148         udev_init_device(&udev, devpath, subsystem, action);
 149
 150         if (!action || !subsystem || !devpath) {
 151                 err("action, subsystem or devpath missing");
 152                 goto hotplug;
 153         }
 154
 155         /* export logging flag, as called programs may want to do the same as udev */
 156         if (udev_log_priority) {
 157                 char priority[32];
 158
 159                 sprintf(priority, "%i", udev_log_priority);
 160                 setenv("UDEV_LOG", priority, 1);
 161         }
 162
 163         if (udev.type == DEV_BLOCK || udev.type == DEV_CLASS || udev.type == DEV_NET) {
 164                 udev_rules_init();
 165
 166                 if (strcmp(action, "add") == 0) {
 167                         /* wait for sysfs and possibly add node */
 168                         dbg("udev add");
 169
 170                         /* skip subsystems without "dev", but handle net devices */
 171                         if (udev.type != DEV_NET && subsystem_expect_no_dev(udev.subsystem)) {
 172                                 dbg("don't care about '%s' devices", udev.subsystem);
 173                                 goto hotplug;
 174                         }
 175
 176                         snprintf(path, sizeof(path), "%s%s", sysfs_path, udev.devpath);
 177                         path[sizeof(path)-1] = '\0';
 178                         class_dev = wait_class_device_open(path);
 179                         if (class_dev == NULL) {
 180                                 dbg("open class device failed");
 181                                 goto hotplug;
 182                         }
 183                         dbg("opened class_dev->name='%s'", class_dev->name);
 184
 185                         wait_for_class_device(class_dev, &error);
 186
 187                         /* name, create node, store in db */
 188                         retval = udev_add_device(&udev, class_dev);
 189
 190                         sysfs_close_class_device(class_dev);
 191                 } else if (strcmp(action, "remove") == 0) {
 192                         /* possibly remove a node */
 193                         dbg("udev remove");
 194
 195                         /* skip subsystems without "dev" */
 196                         if (subsystem_expect_no_dev(udev.subsystem)) {
 197                                 dbg("don't care about '%s' devices", udev.subsystem);
 198                                 goto hotplug;
 199                         }
 200
 201                         udev_rules_get_run(&udev);
 202                         if (udev.ignore_device) {
 203                                 dbg("device event will be ignored");
 204                                 goto hotplug;
 205                         }
 206
 207                         /* get node from db, remove db-entry, delete created node */
 208                         retval = udev_remove_device(&udev);
 209                 }
 210
 211                 if (udev.devname[0] != '\0')
 212                         setenv("DEVNAME", udev.devname, 1);
 213
 214                 if (udev_run && !list_empty(&udev.run_list)) {
 215                         struct name_entry *name_loop;
 216
 217                         dbg("executing run list");
 218                         list_for_each_entry(name_loop, &udev.run_list, node)
 219                                 execute_command(name_loop->name, udev.subsystem);
 220                 }
 221
 222         } else if (udev.type == DEV_DEVICE) {
 223                 if (strcmp(action, "add") == 0) {
 224                         /* wait for sysfs */
 225                         dbg("devices add");
 226
 227                         snprintf(path, sizeof(path), "%s%s", sysfs_path, devpath);
 228                         path[sizeof(path)-1] = '\0';
 229                         devices_dev = wait_devices_device_open(path);
 230                         if (!devices_dev) {
 231                                 dbg("devices device unavailable (probably remove has beaten us)");
 232                                 goto hotplug;
 233                         }
 234                         dbg("devices device opened '%s'", path);
 235
 236                         wait_for_devices_device(devices_dev, &error);
 237
 238                         sysfs_close_device(devices_dev);
 239                 } else if (strcmp(action, "remove") == 0) {
 240                         dbg("devices remove");
 241                 }
 242         } else {
 243                 dbg("unhandled");
 244         }
 245
 246 hotplug:
 247         if (udev_hotplug_d && managed_event)
 248                 udev_multiplex_directory(&udev, HOTPLUGD_DIR, HOTPLUG_SUFFIX);
 249
 250         udev_cleanup_device(&udev);
 251
 252         logging_close();
 253         return retval;
 254 }