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         char *alias = NULL;
  35
  36         /* Force the configuration file settings exactly. */
  37         umask(0);
  38
  39         /* Try to read major/minor string.  Note that the kernel puts \n after
  40          * the data, so we don't need to worry about null terminating the string
  41          * because sscanf() will stop at the first nondigit, which \n is.  We
  42          * also depend on path having writeable space after it.
  43          */
  44         if (!delete) {
  45                 strcat(path, "/dev");
  46                 len = open_read_close(path, temp + 1, 64);
  47                 *temp++ = 0;
  48                 if (len < 1)
  49                         return;
  50         }
  51
  52         /* Determine device name, type, major and minor */
  53         device_name = bb_basename(path);
  54         type = (path[5] == 'c' ? S_IFCHR : S_IFBLK);
  55
  56         if (ENABLE_FEATURE_MDEV_CONF) {
  57                 FILE *fp;
  58                 char *line, *vline;
  59                 unsigned lineno = 0;
  60
  61                 /* If we have a config file, look up the user settings */
  62                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  63                 if (!fp)
  64                         goto end_parse;
  65
  66                 while ((vline = line = xmalloc_getline(fp)) != NULL) {
  67                         int field;
  68
  69                         /* A pristine copy for command execution. */
  70                         char *orig_line;
  71                         if (ENABLE_FEATURE_MDEV_EXEC)
  72                                 orig_line = xstrdup(line);
  73
  74                         ++lineno;
  75
  76                         /* Three fields: regex, uid:gid, mode */
  77                         for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_RENAME + ENABLE_FEATURE_MDEV_EXEC); ++field) {
  78
  79                                 /* Find a non-empty field */
  80                                 char *val;
  81                                 do {
  82                                         val = strtok(vline, " \t");
  83                                         vline = NULL;
  84                                 } while (val && !*val);
  85                                 if (!val) {
  86                                         if (field)
  87                                                 break;
  88                                         else
  89                                                 goto next_line;
  90                                 }
  91
  92                                 if (field == 0) {
  93
  94                                         /* Regex to match this device */
  95                                         regex_t match;
  96                                         regmatch_t off;
  97                                         int result;
  98
  99                                         /* Is this it? */
 100                                         xregcomp(&match, val, REG_EXTENDED);
 101                                         result = regexec(&match, device_name, 1, &off, 0);
 102                                         regfree(&match);
 103
 104                                         /* If not this device, skip rest of line */
 105                                         if (result || off.rm_so || off.rm_eo != strlen(device_name))
 106                                                 goto next_line;
 107
 108                                 } else if (field == 1) {
 109
 110                                         /* uid:gid device ownership */
 111                                         struct passwd *pass;
 112                                         struct group *grp;
 113
 114                                         char *str_uid = val;
 115                                         char *str_gid = strchr(val, ':');
 116                                         if (str_gid)
 117                                                 *str_gid = '\0', ++str_gid;
 118
 119                                         /* Parse UID */
 120                                         pass = getpwnam(str_uid);
 121                                         if (pass)
 122                                                 uid = pass->pw_uid;
 123                                         else
 124                                                 uid = strtoul(str_uid, NULL, 10);
 125
 126                                         /* parse GID */
 127                                         grp = getgrnam(str_gid);
 128                                         if (grp)
 129                                                 gid = grp->gr_gid;
 130                                         else
 131                                                 gid = strtoul(str_gid, NULL, 10);
 132
 133                                 } else if (field == 2) {
 134
 135                                         /* Mode device permissions */
 136                                         mode = strtoul(val, NULL, 8);
 137
 138                                 } else if (ENABLE_FEATURE_MDEV_RENAME && field == 3) {
 139
 140                                         if (*val != '>')
 141                                                 ++field;
 142                                         else
 143                                                 alias = xstrdup(val + 1);
 144
 145                                 }
 146
 147                                 if (ENABLE_FEATURE_MDEV_EXEC && field == 3 + ENABLE_FEATURE_MDEV_RENAME) {
 148
 149                                         /* Optional command to run */
 150                                         const char *s = "@$*";
 151                                         const char *s2 = strchr(s, *val);
 152
 153                                         if (!s2) {
 154                                                 /* Force error */
 155                                                 field = 1;
 156                                                 break;
 157                                         }
 158
 159                                         /* Correlate the position in the "@$*" with the delete
 160                                          * step so that we get the proper behavior.
 161                                          */
 162                                         if ((s2 - s + 1) & (1 << delete))
 163                                                 command = xstrdup(orig_line + (val + 1 - line));
 164                                 }
 165                         }
 166
 167                         /* Did everything parse happily? */
 168                         if (field <= 2)
 169                                 bb_error_msg_and_die("bad line %u", lineno);
 170
 171  next_line:
 172                         free(line);
 173                         if (ENABLE_FEATURE_MDEV_EXEC)
 174                                 free(orig_line);
 175                 }
 176
 177                 if (ENABLE_FEATURE_CLEAN_UP)
 178                         fclose(fp);
 179
 180  end_parse:     /* nothing */ ;
 181         }
 182
 183         if (!delete) {
 184                 if (sscanf(temp, "%d:%d", &major, &minor) != 2)
 185                         return;
 186
 187                 if (ENABLE_FEATURE_MDEV_RENAME)
 188                         unlink(device_name);
 189
 190                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 191                         bb_perror_msg_and_die("mknod %s", device_name);
 192
 193                 if (major == root_major && minor == root_minor)
 194                         symlink(device_name, "root");
 195
 196                 if (ENABLE_FEATURE_MDEV_CONF) {
 197                         chown(device_name, uid, gid);
 198
 199                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 200                                 char *dest;
 201
 202                                 temp = strrchr(alias, '/');
 203                                 if (temp) {
 204                                         if (temp[1] != '\0')
 205                                                 /* given a file name, so rename it */
 206                                                 *temp = '\0';
 207                                         bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 208                                         dest = concat_path_file(alias, device_name);
 209                                 } else
 210                                         dest = alias;
 211
 212                                 rename(device_name, dest); // TODO: xrename?
 213                                 symlink(dest, device_name);
 214
 215                                 if (alias != dest)
 216                                         free(alias);
 217                                 free(dest);
 218                         }
 219                 }
 220         }
 221         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 222                 /* setenv will leak memory, so use putenv */
 223                 char *s = xasprintf("MDEV=%s", device_name);
 224                 putenv(s);
 225                 if (system(command) == -1)
 226                         bb_perror_msg_and_die("cannot run %s", command);
 227                 s[4] = '\0';
 228                 unsetenv(s);
 229                 free(s);
 230                 free(command);
 231         }
 232         if (delete)
 233                 remove_file(device_name, FILEUTILS_FORCE);
 234 }
 235
 236 /* File callback for /sys/ traversal */
 237 static int fileAction(const char *fileName, struct stat *statbuf,
 238                       void *userData, int depth)
 239 {
 240         size_t len = strlen(fileName) - 4;
 241         char *scratch = userData;
 242
 243         if (strcmp(fileName + len, "/dev"))
 244                 return FALSE;
 245
 246         strcpy(scratch, fileName);
 247         scratch[len] = 0;
 248         make_device(scratch, 0);
 249
 250         return TRUE;
 251 }
 252
 253 /* Directory callback for /sys/ traversal */
 254 static int dirAction(const char *fileName, struct stat *statbuf,
 255                       void *userData, int depth)
 256 {
 257         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 258 }
 259
 260 /* For the full gory details, see linux/Documentation/firmware_class/README
 261  *
 262  * Firmware loading works like this:
 263  * - kernel sets FIRMWARE env var
 264  * - userspace checks /lib/firmware/$FIRMWARE
 265  * - userspace waits for /sys/$DEVPATH/loading to appear
 266  * - userspace writes "1" to /sys/$DEVPATH/loading
 267  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 268  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 269  * - kernel loads firmware into device
 270  */
 271 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 272 {
 273         int cnt;
 274         int firmware_fd, loading_fd, data_fd;
 275
 276         /* check for $FIRMWARE from kernel */
 277         /* XXX: dont bother: open(NULL) works same as open("no-such-file")
 278          * if (!firmware)
 279          *      return;
 280          */
 281
 282         /* check for /lib/firmware/$FIRMWARE */
 283         xchdir("/lib/firmware");
 284         firmware_fd = xopen(firmware, O_RDONLY);
 285
 286         /* in case we goto out ... */
 287         data_fd = -1;
 288
 289         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 290         xchdir(sysfs_path);
 291         for (cnt = 0; cnt < 30; ++cnt) {
 292                 loading_fd = open("loading", O_WRONLY);
 293                 if (loading_fd == -1)
 294                         sleep(1);
 295                 else
 296                         break;
 297         }
 298         if (loading_fd == -1)
 299                 goto out;
 300
 301         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 302         if (write(loading_fd, "1", 1) != 1)
 303                 goto out;
 304
 305         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 306         data_fd = open("data", O_WRONLY);
 307         if (data_fd == -1)
 308                 goto out;
 309         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 310
 311         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 312         if (cnt > 0)
 313                 write(loading_fd, "0", 1);
 314         else
 315                 write(loading_fd, "-1", 2);
 316
 317  out:
 318         if (ENABLE_FEATURE_CLEAN_UP) {
 319                 close(firmware_fd);
 320                 close(loading_fd);
 321                 close(data_fd);
 322         }
 323 }
 324
 325 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 326 int mdev_main(int argc, char **argv)
 327 {
 328         char *action;
 329         char *env_path;
 330         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 331
 332         xchdir("/dev");
 333
 334         if (argc == 2 && !strcmp(argv[1],"-s")) {
 335
 336                 /* Scan:
 337                  * mdev -s
 338                  */
 339
 340                 struct stat st;
 341
 342                 xstat("/", &st);
 343                 root_major = major(st.st_dev);
 344                 root_minor = minor(st.st_dev);
 345
 346                 recursive_action("/sys/block",
 347                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 348                         fileAction, dirAction, temp, 0);
 349
 350                 recursive_action("/sys/class",
 351                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 352                         fileAction, dirAction, temp, 0);
 353
 354         } else {
 355
 356                 /* Hotplug:
 357                  * env ACTION=... DEVPATH=... mdev
 358                  * ACTION can be "add" or "remove"
 359                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 360                  */
 361
 362                 action = getenv("ACTION");
 363                 env_path = getenv("DEVPATH");
 364                 if (!action || !env_path)
 365                         bb_show_usage();
 366
 367                 sprintf(temp, "/sys%s", env_path);
 368                 if (!strcmp(action, "remove"))
 369                         make_device(temp, 1);
 370                 else if (!strcmp(action, "add")) {
 371                         make_device(temp, 0);
 372
 373                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE)
 374                                 load_firmware(getenv("FIRMWARE"), temp);
 375                 }
 376         }
 377
 378         if (ENABLE_FEATURE_CLEAN_UP)
 379                 RELEASE_CONFIG_BUFFER(temp);
 380
 381         return 0;
 382 }