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 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 sysfs_class_device *class_dev;
 100         struct sysfs_device *devices_dev;
 101         struct udevice udev;
 102         char path[PATH_SIZE];
 103         const char *error;
 104         const char *action;
 105         const char *devpath;
 106         const char *subsystem;
 107         int managed_event;
 108         struct sigaction act;
 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         udev_init_config();
 118         dbg("version %s", UDEV_VERSION);
 119
 120         /* set signal handlers */
 121         memset(&act, 0x00, sizeof(act));
 122         act.sa_handler = (void (*)(int)) sig_handler;
 123         sigemptyset (&act.sa_mask);
 124         act.sa_flags = 0;
 125         sigaction(SIGALRM, &act, NULL);
 126         sigaction(SIGINT, &act, NULL);
 127         sigaction(SIGTERM, &act, NULL);
 128
 129         /* trigger timeout to prevent hanging processes */
 130         alarm(ALARM_TIMEOUT);
 131
 132         /* let the executed programs know if we handle the whole hotplug event */
 133         managed_event = manage_hotplug_event();
 134         if (managed_event)
 135                 setenv("MANAGED_EVENT", "1", 1);
 136
 137         action = getenv("ACTION");
 138         devpath = getenv("DEVPATH");
 139         subsystem = getenv("SUBSYSTEM");
 140         /* older kernels passed the SUBSYSTEM only as argument */
 141         if (!subsystem && argc == 2)
 142                 subsystem = argv[1];
 143
 144         udev_init_device(&udev, devpath, subsystem, action);
 145
 146         if (!action || !subsystem || !devpath) {
 147                 err("action, subsystem or devpath missing");
 148                 goto hotplug;
 149         }
 150
 151         /* export logging flag, as called scripts may want to do the same as udev */
 152         if (udev_log_priority) {
 153                 char priority[32];
 154
 155                 sprintf(priority, "%i", udev_log_priority);
 156                 setenv("UDEV_LOG", priority, 1);
 157         }
 158
 159         if (udev.type == DEV_BLOCK || udev.type == DEV_CLASS || udev.type == DEV_NET) {
 160                 udev_rules_init();
 161
 162                 if (strcmp(action, "add") == 0) {
 163                         /* wait for sysfs and possibly add node */
 164                         dbg("udev add");
 165
 166                         /* skip subsystems without "dev", but handle net devices */
 167                         if (udev.type != DEV_NET && subsystem_expect_no_dev(udev.subsystem)) {
 168                                 dbg("don't care about '%s' devices", udev.subsystem);
 169                                 goto hotplug;
 170                         }
 171
 172                         snprintf(path, sizeof(path), "%s%s", sysfs_path, udev.devpath);
 173                         path[sizeof(path)-1] = '\0';
 174                         class_dev = wait_class_device_open(path);
 175                         if (class_dev == NULL) {
 176                                 dbg("open class device failed");
 177                                 goto hotplug;
 178                         }
 179                         dbg("opened class_dev->name='%s'", class_dev->name);
 180
 181                         wait_for_class_device(class_dev, &error);
 182
 183                         /* name, create node, store in db */
 184                         retval = udev_add_device(&udev, class_dev);
 185
 186                         sysfs_close_class_device(class_dev);
 187                 } else if (strcmp(action, "remove") == 0) {
 188                         /* possibly remove a node */
 189                         dbg("udev remove");
 190
 191                         /* skip subsystems without "dev" */
 192                         if (subsystem_expect_no_dev(udev.subsystem)) {
 193                                 dbg("don't care about '%s' devices", udev.subsystem);
 194                                 goto hotplug;
 195                         }
 196
 197                         udev_rules_get_run(&udev);
 198                         if (udev.ignore_device) {
 199                                 dbg("device event will be ignored");
 200                                 goto hotplug;
 201                         }
 202
 203                         /* get node from db, remove db-entry, delete created node */
 204                         retval = udev_remove_device(&udev);
 205                 }
 206
 207                 if (udev.devname[0] != '\0')
 208                         setenv("DEVNAME", udev.devname, 1);
 209
 210                 if (udev_run && !list_empty(&udev.run_list)) {
 211                         struct name_entry *name_loop;
 212
 213                         dbg("executing run list");
 214                         list_for_each_entry(name_loop, &udev.run_list, node)
 215                                 execute_command(name_loop->name, udev.subsystem);
 216                 }
 217
 218                 /* run dev.d/ scripts if we created/deleted a node or changed a netif name */
 219                 if (udev_dev_d && udev.devname[0] != '\0')
 220                         udev_multiplex_directory(&udev, DEVD_DIR, DEVD_SUFFIX);
 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 }