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                         if (ENABLE_FEATURE_MDEV_EXEC)
  50                                 /* no "dev" file, so just try to run script */
  51                                 *temp = 0;
  52                         else
  53                                 return;
  54                 }
  55         }
  56
  57         /* Determine device name, type, major and minor */
  58         device_name = bb_basename(path);
  59         type = (path[5] == 'c' ? S_IFCHR : S_IFBLK);
  60
  61         if (ENABLE_FEATURE_MDEV_CONF) {
  62                 FILE *fp;
  63                 char *line, *vline;
  64                 unsigned lineno = 0;
  65
  66                 /* If we have a config file, look up the user settings */
  67                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  68                 if (!fp)
  69                         goto end_parse;
  70
  71                 while ((vline = line = xmalloc_fgetline(fp)) != NULL) {
  72                         int field;
  73
  74                         /* A pristine copy for command execution. */
  75                         char *orig_line;
  76                         if (ENABLE_FEATURE_MDEV_EXEC)
  77                                 orig_line = xstrdup(line);
  78
  79                         ++lineno;
  80
  81                         /* Three fields: regex, uid:gid, mode */
  82                         for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_RENAME + ENABLE_FEATURE_MDEV_EXEC); ++field) {
  83
  84                                 /* Find a non-empty field */
  85                                 char *val;
  86                                 do {
  87                                         val = strtok(vline, " \t");
  88                                         vline = NULL;
  89                                 } while (val && !*val);
  90                                 if (!val) {
  91                                         if (field)
  92                                                 break;
  93                                         else
  94                                                 goto next_line;
  95                                 }
  96
  97                                 if (field == 0) {
  98
  99                                         /* Regex to match this device */
 100                                         regex_t match;
 101                                         regmatch_t off;
 102                                         int result;
 103
 104                                         /* Is this it? */
 105                                         xregcomp(&match, val, REG_EXTENDED);
 106                                         result = regexec(&match, device_name, 1, &off, 0);
 107                                         regfree(&match);
 108
 109                                         /* If not this device, skip rest of line */
 110                                         if (result || off.rm_so || off.rm_eo != strlen(device_name))
 111                                                 goto next_line;
 112
 113                                 } else if (field == 1) {
 114
 115                                         /* uid:gid device ownership */
 116                                         struct passwd *pass;
 117                                         struct group *grp;
 118
 119                                         char *str_uid = val;
 120                                         char *str_gid = strchr(val, ':');
 121                                         if (str_gid)
 122                                                 *str_gid = '\0', ++str_gid;
 123
 124                                         /* Parse UID */
 125                                         pass = getpwnam(str_uid);
 126                                         if (pass)
 127                                                 uid = pass->pw_uid;
 128                                         else
 129                                                 uid = strtoul(str_uid, NULL, 10);
 130
 131                                         /* parse GID */
 132                                         grp = getgrnam(str_gid);
 133                                         if (grp)
 134                                                 gid = grp->gr_gid;
 135                                         else
 136                                                 gid = strtoul(str_gid, NULL, 10);
 137
 138                                 } else if (field == 2) {
 139
 140                                         /* Mode device permissions */
 141                                         mode = strtoul(val, NULL, 8);
 142
 143                                 } else if (ENABLE_FEATURE_MDEV_RENAME && field == 3) {
 144
 145                                         if (*val != '>')
 146                                                 ++field;
 147                                         else
 148                                                 alias = xstrdup(val + 1);
 149
 150                                 }
 151
 152                                 if (ENABLE_FEATURE_MDEV_EXEC && field == 3 + ENABLE_FEATURE_MDEV_RENAME) {
 153
 154                                         /* Optional command to run */
 155                                         const char *s = "@$*";
 156                                         const char *s2 = strchr(s, *val);
 157
 158                                         if (!s2) {
 159                                                 /* Force error */
 160                                                 field = 1;
 161                                                 break;
 162                                         }
 163
 164                                         /* Correlate the position in the "@$*" with the delete
 165                                          * step so that we get the proper behavior.
 166                                          */
 167                                         if ((s2 - s + 1) & (1 << delete))
 168                                                 command = xstrdup(orig_line + (val + 1 - line));
 169                                 }
 170                         }
 171
 172                         /* Did everything parse happily? */
 173                         if (field <= 2)
 174                                 bb_error_msg_and_die("bad line %u", lineno);
 175
 176  next_line:
 177                         free(line);
 178                         if (ENABLE_FEATURE_MDEV_EXEC)
 179                                 free(orig_line);
 180                 }
 181
 182                 if (ENABLE_FEATURE_CLEAN_UP)
 183                         fclose(fp);
 184
 185  end_parse:     /* nothing */ ;
 186         }
 187
 188         if (!delete) {
 189                 if (sscanf(temp, "%d:%d", &major, &minor) != 2) {
 190                         if (ENABLE_FEATURE_MDEV_EXEC)
 191                                 goto skip_creation;
 192                         else
 193                                 return;
 194                 }
 195
 196                 if (ENABLE_FEATURE_MDEV_RENAME)
 197                         unlink(device_name);
 198
 199                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 200                         bb_perror_msg_and_die("mknod %s", device_name);
 201
 202                 if (major == root_major && minor == root_minor)
 203                         symlink(device_name, "root");
 204
 205                 if (ENABLE_FEATURE_MDEV_CONF) {
 206                         chown(device_name, uid, gid);
 207
 208                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 209                                 char *dest;
 210
 211                                 temp = strrchr(alias, '/');
 212                                 if (temp) {
 213                                         if (temp[1] != '\0')
 214                                                 /* given a file name, so rename it */
 215                                                 *temp = '\0';
 216                                         bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 217                                         dest = concat_path_file(alias, device_name);
 218                                 } else
 219                                         dest = alias;
 220
 221                                 rename(device_name, dest); // TODO: xrename?
 222                                 symlink(dest, device_name);
 223
 224                                 if (alias != dest)
 225                                         free(alias);
 226                                 free(dest);
 227                         }
 228                 }
 229  skip_creation: /* nothing */ ;
 230         }
 231         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 232                 /* setenv will leak memory, so use putenv */
 233                 char *s = xasprintf("MDEV=%s", device_name);
 234                 putenv(s);
 235                 if (system(command) == -1)
 236                         bb_perror_msg_and_die("cannot run %s", command);
 237                 s[4] = '\0';
 238                 unsetenv(s);
 239                 free(s);
 240                 free(command);
 241         }
 242         if (delete)
 243                 remove_file(device_name, FILEUTILS_FORCE);
 244 }
 245
 246 /* File callback for /sys/ traversal */
 247 static int fileAction(const char *fileName,
 248                       struct stat *statbuf ATTRIBUTE_UNUSED,
 249                       void *userData,
 250                       int depth ATTRIBUTE_UNUSED)
 251 {
 252         size_t len = strlen(fileName) - 4;
 253         char *scratch = userData;
 254
 255         if (strcmp(fileName + len, "/dev"))
 256                 return FALSE;
 257
 258         strcpy(scratch, fileName);
 259         scratch[len] = 0;
 260         make_device(scratch, 0);
 261
 262         return TRUE;
 263 }
 264
 265 /* Directory callback for /sys/ traversal */
 266 static int dirAction(const char *fileName ATTRIBUTE_UNUSED,
 267                       struct stat *statbuf ATTRIBUTE_UNUSED,
 268                       void *userData ATTRIBUTE_UNUSED,
 269                       int depth)
 270 {
 271         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 272 }
 273
 274 /* For the full gory details, see linux/Documentation/firmware_class/README
 275  *
 276  * Firmware loading works like this:
 277  * - kernel sets FIRMWARE env var
 278  * - userspace checks /lib/firmware/$FIRMWARE
 279  * - userspace waits for /sys/$DEVPATH/loading to appear
 280  * - userspace writes "1" to /sys/$DEVPATH/loading
 281  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 282  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 283  * - kernel loads firmware into device
 284  */
 285 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 286 {
 287         int cnt;
 288         int firmware_fd, loading_fd, data_fd;
 289
 290         /* check for $FIRMWARE from kernel */
 291         /* XXX: dont bother: open(NULL) works same as open("no-such-file")
 292          * if (!firmware)
 293          *      return;
 294          */
 295
 296         /* check for /lib/firmware/$FIRMWARE */
 297         xchdir("/lib/firmware");
 298         firmware_fd = xopen(firmware, O_RDONLY);
 299
 300         /* in case we goto out ... */
 301         data_fd = -1;
 302
 303         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 304         xchdir(sysfs_path);
 305         for (cnt = 0; cnt < 30; ++cnt) {
 306                 loading_fd = open("loading", O_WRONLY);
 307                 if (loading_fd == -1)
 308                         sleep(1);
 309                 else
 310                         break;
 311         }
 312         if (loading_fd == -1)
 313                 goto out;
 314
 315         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 316         if (write(loading_fd, "1", 1) != 1)
 317                 goto out;
 318
 319         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 320         data_fd = open("data", O_WRONLY);
 321         if (data_fd == -1)
 322                 goto out;
 323         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 324
 325         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 326         if (cnt > 0)
 327                 write(loading_fd, "0", 1);
 328         else
 329                 write(loading_fd, "-1", 2);
 330
 331  out:
 332         if (ENABLE_FEATURE_CLEAN_UP) {
 333                 close(firmware_fd);
 334                 close(loading_fd);
 335                 close(data_fd);
 336         }
 337 }
 338
 339 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 340 int mdev_main(int argc, char **argv)
 341 {
 342         char *action;
 343         char *env_path;
 344         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 345
 346         xchdir("/dev");
 347
 348         if (argc == 2 && !strcmp(argv[1],"-s")) {
 349
 350                 /* Scan:
 351                  * mdev -s
 352                  */
 353
 354                 struct stat st;
 355
 356                 xstat("/", &st);
 357                 root_major = major(st.st_dev);
 358                 root_minor = minor(st.st_dev);
 359
 360                 recursive_action("/sys/block",
 361                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 362                         fileAction, dirAction, temp, 0);
 363
 364                 recursive_action("/sys/class",
 365                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 366                         fileAction, dirAction, temp, 0);
 367
 368         } else {
 369
 370                 /* Hotplug:
 371                  * env ACTION=... DEVPATH=... mdev
 372                  * ACTION can be "add" or "remove"
 373                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 374                  */
 375
 376                 action = getenv("ACTION");
 377                 env_path = getenv("DEVPATH");
 378                 if (!action || !env_path)
 379                         bb_show_usage();
 380
 381                 sprintf(temp, "/sys%s", env_path);
 382                 if (!strcmp(action, "remove"))
 383                         make_device(temp, 1);
 384                 else if (!strcmp(action, "add")) {
 385                         make_device(temp, 0);
 386
 387                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE)
 388                                 load_firmware(getenv("FIRMWARE"), temp);
 389                 }
 390         }
 391
 392         if (ENABLE_FEATURE_CLEAN_UP)
 393                 RELEASE_CONFIG_BUFFER(temp);
 394
 395         return 0;
 396 }