util-linux/mdev.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  *
   4  * mdev - Mini udev for busybox
   5  *
   6  * Copyright 2005 Rob Landley <rob@landley.net>
   7  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   8  *
   9  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  10  */
  11
  12 #include "libbb.h"
  13 #include "xregex.h"
  14
  15 struct globals {
  16         int root_major, root_minor;
  17 };
  18 #define G (*(struct globals*)&bb_common_bufsiz1)
  19 #define root_major (G.root_major)
  20 #define root_minor (G.root_minor)
  21
  22 #define MAX_SYSFS_DEPTH 3 /* prevent infinite loops in /sys symlinks */
  23
  24 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  25 static void make_device(char *path, int delete)
  26 {
  27         const char *device_name;
  28         int major, minor, type, len;
  29         int mode = 0660;
  30         uid_t uid = 0;
  31         gid_t gid = 0;
  32         char *temp = path + strlen(path);
  33         char *command = NULL;
  34
  35         /* Try to read major/minor string.  Note that the kernel puts \n after
  36          * the data, so we don't need to worry about null terminating the string
  37          * because sscanf() will stop at the first nondigit, which \n is.  We
  38          * also depend on path having writeable space after it.
  39          */
  40         if (!delete) {
  41                 strcat(path, "/dev");
  42                 len = open_read_close(path, temp + 1, 64);
  43                 *temp++ = 0;
  44                 if (len < 1)
  45                         return;
  46         }
  47
  48         /* Determine device name, type, major and minor */
  49         device_name = bb_basename(path);
  50         type = (path[5] == 'c' ? S_IFCHR : S_IFBLK);
  51
  52         if (ENABLE_FEATURE_MDEV_CONF) {
  53                 FILE *fp;
  54                 char *line, *vline;
  55                 size_t lineno = 0;
  56
  57                 /* If we have a config file, look up the user settings */
  58                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  59                 if (!fp)
  60                         goto end_parse;
  61
  62                 while ((vline = line = xmalloc_getline(fp)) != NULL) {
  63                         int field;
  64
  65                         /* A pristine copy for command execution. */
  66                         char *orig_line;
  67                         if (ENABLE_FEATURE_MDEV_EXEC)
  68                                 orig_line = xstrdup(line);
  69
  70                         ++lineno;
  71
  72                         /* Three fields: regex, uid:gid, mode */
  73                         for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_EXEC); ++field) {
  74
  75                                 /* Find a non-empty field */
  76                                 char *val;
  77                                 do {
  78                                         val = strtok(vline, " \t");
  79                                         vline = NULL;
  80                                 } while (val && !*val);
  81                                 if (!val)
  82                                         break;
  83
  84                                 if (field == 0) {
  85
  86                                         /* Regex to match this device */
  87                                         regex_t match;
  88                                         regmatch_t off;
  89                                         int result;
  90
  91                                         /* Is this it? */
  92                                         xregcomp(&match, val, REG_EXTENDED);
  93                                         result = regexec(&match, device_name, 1, &off, 0);
  94                                         regfree(&match);
  95
  96                                         /* If not this device, skip rest of line */
  97                                         if (result || off.rm_so || off.rm_eo != strlen(device_name))
  98                                                 goto next_line;
  99
 100                                 } else if (field == 1) {
 101
 102                                         /* uid:gid device ownership */
 103                                         struct passwd *pass;
 104                                         struct group *grp;
 105
 106                                         char *str_uid = val;
 107                                         char *str_gid = strchr(val, ':');
 108                                         if (str_gid)
 109                                                 *str_gid = '\0', ++str_gid;
 110
 111                                         /* Parse UID */
 112                                         pass = getpwnam(str_uid);
 113                                         if (pass)
 114                                                 uid = pass->pw_uid;
 115                                         else
 116                                                 uid = strtoul(str_uid, NULL, 10);
 117
 118                                         /* parse GID */
 119                                         grp = getgrnam(str_gid);
 120                                         if (grp)
 121                                                 gid = grp->gr_gid;
 122                                         else
 123                                                 gid = strtoul(str_gid, NULL, 10);
 124
 125                                 } else if (field == 2) {
 126
 127                                         /* Mode device permissions */
 128                                         mode = strtoul(val, NULL, 8);
 129
 130                                 } else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
 131
 132                                         /* Optional command to run */
 133                                         const char *s = "@$*";
 134                                         const char *s2 = strchr(s, *val);
 135
 136                                         if (!s2) {
 137                                                 /* Force error */
 138                                                 field = 1;
 139                                                 break;
 140                                         }
 141
 142                                         /* Correlate the position in the "@$*" with the delete
 143                                          * step so that we get the proper behavior.
 144                                          */
 145                                         if ((s2 - s + 1) & (1 << delete))
 146                                                 command = xstrdup(orig_line + (val + 1 - line));
 147                                 }
 148                         }
 149
 150                         /* Did everything parse happily? */
 151                         if (field <= 2)
 152                                 bb_error_msg_and_die("bad line %i", lineno);
 153
 154  next_line:
 155                         free(line);
 156                         if (ENABLE_FEATURE_MDEV_EXEC)
 157                                 free(orig_line);
 158                 }
 159
 160                 if (ENABLE_FEATURE_CLEAN_UP)
 161                         fclose(fp);
 162
 163  end_parse:     /* nothing */ ;
 164         }
 165
 166         umask(0);
 167         if (!delete) {
 168                 if (sscanf(temp, "%d:%d", &major, &minor) != 2)
 169                         return;
 170                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 171                         bb_perror_msg_and_die("mknod %s", device_name);
 172
 173                 if (major == root_major && minor == root_minor)
 174                         symlink(device_name, "root");
 175
 176                 if (ENABLE_FEATURE_MDEV_CONF)
 177                         chown(device_name, uid, gid);
 178         }
 179         if (command) {
 180                 /* setenv will leak memory, so use putenv */
 181                 char *s = xasprintf("MDEV=%s", device_name);
 182                 putenv(s);
 183                 if (system(command) == -1)
 184                         bb_perror_msg_and_die("cannot run %s", command);
 185                 s[4] = '\0';
 186                 unsetenv(s);
 187                 free(s);
 188                 free(command);
 189         }
 190         if (delete)
 191                 remove_file(device_name, FILEUTILS_FORCE);
 192 }
 193
 194 /* File callback for /sys/ traversal */
 195 static int fileAction(const char *fileName, struct stat *statbuf,
 196                       void *userData, int depth)
 197 {
 198         size_t len = strlen(fileName) - 4;
 199         char *scratch = userData;
 200
 201         if (strcmp(fileName + len, "/dev"))
 202                 return FALSE;
 203
 204         strcpy(scratch, fileName);
 205         scratch[len] = 0;
 206         make_device(scratch, 0);
 207
 208         return TRUE;
 209 }
 210
 211 /* Directory callback for /sys/ traversal */
 212 static int dirAction(const char *fileName, struct stat *statbuf,
 213                       void *userData, int depth)
 214 {
 215         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 216 }
 217
 218 /* For the full gory details, see linux/Documentation/firmware_class/README
 219  *
 220  * Firmware loading works like this:
 221  * - kernel sets FIRMWARE env var
 222  * - userspace checks /lib/firmware/$FIRMWARE
 223  * - userspace waits for /sys/$DEVPATH/loading to appear
 224  * - userspace writes "1" to /sys/$DEVPATH/loading
 225  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 226  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 227  * - kernel loads firmware into device
 228  */
 229 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 230 {
 231         int cnt;
 232         int firmware_fd, loading_fd, data_fd;
 233
 234         /* check for $FIRMWARE from kernel */
 235         /* XXX: dont bother: open(NULL) works same as open("no-such-file")
 236          * if (!firmware)
 237          *      return;
 238          */
 239
 240         /* check for /lib/firmware/$FIRMWARE */
 241         xchdir("/lib/firmware");
 242         firmware_fd = xopen(firmware, O_RDONLY);
 243
 244         /* in case we goto out ... */
 245         data_fd = -1;
 246
 247         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 248         xchdir(sysfs_path);
 249         for (cnt = 0; cnt < 30; ++cnt) {
 250                 loading_fd = open("loading", O_WRONLY);
 251                 if (loading_fd == -1)
 252                         sleep(1);
 253                 else
 254                         break;
 255         }
 256         if (loading_fd == -1)
 257                 goto out;
 258
 259         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 260         if (write(loading_fd, "1", 1) != 1)
 261                 goto out;
 262
 263         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 264         data_fd = open("data", O_WRONLY);
 265         if (data_fd == -1)
 266                 goto out;
 267         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 268
 269         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 270         if (cnt > 0)
 271                 write(loading_fd, "0", 1);
 272         else
 273                 write(loading_fd, "-1", 2);
 274
 275  out:
 276         if (ENABLE_FEATURE_CLEAN_UP) {
 277                 close(firmware_fd);
 278                 close(loading_fd);
 279                 close(data_fd);
 280         }
 281 }
 282
 283 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 284 int mdev_main(int argc, char **argv)
 285 {
 286         char *action;
 287         char *env_path;
 288         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 289
 290         xchdir("/dev");
 291
 292         if (argc == 2 && !strcmp(argv[1],"-s")) {
 293
 294                 /* Scan:
 295                  * mdev -s
 296                  */
 297
 298                 struct stat st;
 299
 300                 xstat("/", &st);
 301                 root_major = major(st.st_dev);
 302                 root_minor = minor(st.st_dev);
 303
 304                 recursive_action("/sys/block",
 305                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 306                         fileAction, dirAction, temp, 0);
 307
 308                 recursive_action("/sys/class",
 309                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 310                         fileAction, dirAction, temp, 0);
 311
 312         } else {
 313
 314                 /* Hotplug:
 315                  * env ACTION=... DEVPATH=... mdev
 316                  * ACTION can be "add" or "remove"
 317                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 318                  */
 319
 320                 action = getenv("ACTION");
 321                 env_path = getenv("DEVPATH");
 322                 if (!action || !env_path)
 323                         bb_show_usage();
 324
 325                 sprintf(temp, "/sys%s", env_path);
 326                 if (!strcmp(action, "remove"))
 327                         make_device(temp, 1);
 328                 else if (!strcmp(action, "add")) {
 329                         make_device(temp, 0);
 330
 331                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE)
 332                                 load_firmware(getenv("FIRMWARE"), temp);
 333                 }
 334         }
 335
 336         if (ENABLE_FEATURE_CLEAN_UP)
 337                 RELEASE_CONFIG_BUFFER(temp);
 338
 339         return 0;
 340 }