git.maemo.org Git - busybox4maemo/blob - 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 #define ENABLE_FEATURE_MDEV_RENAME_REGEXP 1
  16
  17 struct globals {
  18         int root_major, root_minor;
  19 };
  20 #define G (*(struct globals*)&bb_common_bufsiz1)
  21 #define root_major (G.root_major)
  22 #define root_minor (G.root_minor)
  23
  24 #define MAX_SYSFS_DEPTH 3 /* prevent infinite loops in /sys symlinks */
  25
  26 /* We use additional 64+ bytes in make_device() */
  27 #define SCRATCH_SIZE 80
  28
  29 static char *next_field(char *s)
  30 {
  31         char *end = skip_non_whitespace(s);
  32         s = skip_whitespace(end);
  33         *end = '\0';
  34         if (*s == '\0')
  35                 s = NULL;
  36         return s;
  37 }
  38
  39 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  40 /* NB: "mdev -s" may call us many times, do not leak memory/fds! */
  41 static void make_device(char *path, int delete)
  42 {
  43         const char *device_name;
  44         int major, minor, type, len;
  45         int mode = 0660;
  46         uid_t uid = 0;
  47         gid_t gid = 0;
  48         char *dev_maj_min = path + strlen(path);
  49         char *command = NULL;
  50         char *alias = NULL;
  51
  52         /* Force the configuration file settings exactly. */
  53         umask(0);
  54
  55         /* Try to read major/minor string.  Note that the kernel puts \n after
  56          * the data, so we don't need to worry about null terminating the string
  57          * because sscanf() will stop at the first nondigit, which \n is.  We
  58          * also depend on path having writeable space after it.
  59          */
  60         if (!delete) {
  61                 strcpy(dev_maj_min, "/dev");
  62                 len = open_read_close(path, dev_maj_min + 1, 64);
  63                 *dev_maj_min++ = '\0';
  64                 if (len < 1) {
  65                         if (!ENABLE_FEATURE_MDEV_EXEC)
  66                                 return;
  67                         /* no "dev" file, so just try to run script */
  68                         *dev_maj_min = '\0';
  69                 }
  70         }
  71
  72         /* Determine device name, type, major and minor */
  73         device_name = bb_basename(path);
  74         /* http://kernel.org/doc/pending/hotplug.txt says that only
  75          * "/sys/block/..." is for block devices. "sys/bus" etc is not! */
  76         type = (strncmp(&path[5], "block/", 6) == 0 ? S_IFBLK : S_IFCHR);
  77
  78         if (ENABLE_FEATURE_MDEV_CONF) {
  79                 FILE *fp;
  80                 char *line, *val, *next;
  81                 unsigned lineno = 0;
  82
  83                 /* If we have config file, look up user settings */
  84                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  85                 if (!fp)
  86                         goto end_parse;
  87
  88                 while ((line = xmalloc_getline(fp)) != NULL) {
  89                         regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
  90
  91                         ++lineno;
  92                         trim(line);
  93                         if (!line[0])
  94                                 goto next_line;
  95
  96                         /* Fields: regex uid:gid mode [alias] [cmd] */
  97
  98                         /* 1st field: regex to match this device */
  99                         next = next_field(line);
 100                         {
 101                                 regex_t match;
 102                                 int result;
 103
 104                                 /* Is this it? */
 105                                 xregcomp(&match, line, REG_EXTENDED);
 106                                 result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
 107                                 regfree(&match);
 108
 109                                 //bb_error_msg("matches:");
 110                                 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 111                                 //      if (off[i].rm_so < 0) continue;
 112                                 //      bb_error_msg("match %d: '%.*s'\n", i,
 113                                 //              (int)(off[i].rm_eo - off[i].rm_so),
 114                                 //              device_name + off[i].rm_so);
 115                                 //}
 116
 117                                 /* If not this device, skip rest of line */
 118                                 /* (regexec returns whole pattern as "range" 0) */
 119                                 if (result || off[0].rm_so || off[0].rm_eo != strlen(device_name))
 120                                         goto next_line;
 121                         }
 122
 123                         /* This line matches: stop parsing the file
 124                          * after parsing the rest of fields */
 125
 126                         /* 2nd field: uid:gid - device ownership */
 127                         if (!next) /* field must exist */
 128                                 bb_error_msg_and_die("bad line %u", lineno);
 129                         val = next;
 130                         next = next_field(val);
 131                         {
 132                                 struct passwd *pass;
 133                                 struct group *grp;
 134                                 char *str_uid = val;
 135                                 char *str_gid = strchrnul(val, ':');
 136
 137                                 if (*str_gid)
 138                                         *str_gid++ = '\0';
 139                                 /* Parse UID */
 140                                 pass = getpwnam(str_uid);
 141                                 if (pass)
 142                                         uid = pass->pw_uid;
 143                                 else
 144                                         uid = strtoul(str_uid, NULL, 10);
 145                                 /* Parse GID */
 146                                 grp = getgrnam(str_gid);
 147                                 if (grp)
 148                                         gid = grp->gr_gid;
 149                                 else
 150                                         gid = strtoul(str_gid, NULL, 10);
 151                         }
 152
 153                         /* 3rd field: mode - device permissions */
 154                         if (!next) /* field must exist */
 155                                 bb_error_msg_and_die("bad line %u", lineno);
 156                         val = next;
 157                         next = next_field(val);
 158                         mode = strtoul(val, NULL, 8);
 159
 160                         /* 4th field (opt): >alias */
 161                         if (ENABLE_FEATURE_MDEV_RENAME) {
 162                                 if (!next)
 163                                         break;
 164                                 if (*next == '>') {
 165 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 166                                         char *s, *p;
 167                                         unsigned i, n;
 168 #endif
 169                                         val = next;
 170                                         next = next_field(val);
 171 #if ENABLE_FEATURE_MDEV_RENAME_REGEXP
 172                                         /* substitute %1..9 with off[1..9], if any */
 173                                         n = 0;
 174                                         s = val;
 175                                         while (*s && *s++ == '%')
 176                                                 n++;
 177
 178                                         p = alias = xzalloc(strlen(val) + n * strlen(device_name));
 179                                         s = val + 1;
 180                                         while (*s) {
 181                                                 *p = *s;
 182                                                 if ('%' == *s) {
 183                                                         i = (s[1] - '0');
 184                                                         if (i <= 9 && off[i].rm_so >= 0) {
 185                                                                 n = off[i].rm_eo - off[i].rm_so;
 186                                                                 strncpy(p, device_name + off[i].rm_so, n);
 187                                                                 p += n - 1;
 188                                                                 s++;
 189                                                         }
 190                                                 }
 191                                                 p++;
 192                                                 s++;
 193                                         }
 194 #else
 195                                         alias = xstrdup(val + 1);
 196 #endif
 197                                 }
 198                         }
 199
 200                         /* The rest (opt): command to run */
 201                         if (!next)
 202                                 break;
 203                         val = next;
 204                         if (ENABLE_FEATURE_MDEV_EXEC) {
 205                                 const char *s = "@$*";
 206                                 const char *s2 = strchr(s, *val);
 207
 208                                 if (!s2)
 209                                         bb_error_msg_and_die("bad line %u", lineno);
 210
 211                                 /* Correlate the position in the "@$*" with the delete
 212                                  * step so that we get the proper behavior:
 213                                  * @cmd: run on create
 214                                  * $cmd: run on delete
 215                                  * *cmd: run on both
 216                                  */
 217                                 if ((s2 - s + 1) /*1/2/3*/ & /*1/2*/ (1 + delete)) {
 218                                         command = xstrdup(val + 1);
 219                                 }
 220                         }
 221                         /* end of field parsing */
 222                         break; /* we found matching line, stop */
 223  next_line:
 224                         free(line);
 225                 } /* end of "while line is read from /etc/mdev.conf" */
 226
 227                 free(line); /* in case we used "break" to get here */
 228                 fclose(fp);
 229         }
 230  end_parse:
 231
 232         if (!delete && sscanf(dev_maj_min, "%u:%u", &major, &minor) == 2) {
 233
 234                 if (ENABLE_FEATURE_MDEV_RENAME)
 235                         unlink(device_name);
 236
 237                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 238                         bb_perror_msg_and_die("mknod %s", device_name);
 239
 240                 if (major == root_major && minor == root_minor)
 241                         symlink(device_name, "root");
 242
 243                 if (ENABLE_FEATURE_MDEV_CONF) {
 244                         chown(device_name, uid, gid);
 245
 246                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 247                                 char *dest;
 248
 249                                 /* ">bar/": rename to bar/device_name */
 250                                 /* ">bar[/]baz": rename to bar[/]baz */
 251                                 dest = strrchr(alias, '/');
 252                                 if (dest) { /* ">bar/[baz]" ? */
 253                                         *dest = '\0'; /* mkdir bar */
 254                                         bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 255                                         *dest = '/';
 256                                         if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 257                                                 dest = alias;
 258                                                 alias = concat_path_file(alias, device_name);
 259                                                 free(dest);
 260                                         }
 261                                 }
 262
 263                                 /* recreate device_name as a symlink to moved device node */
 264                                 if (rename(device_name, alias) == 0) {
 265                                         symlink(alias, device_name);
 266                                 }
 267
 268                                 free(alias);
 269                         }
 270                 }
 271         }
 272
 273         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 274                 /* setenv will leak memory, use putenv/unsetenv/free */
 275                 char *s = xasprintf("MDEV=%s", device_name);
 276                 putenv(s);
 277                 if (system(command) == -1)
 278                         bb_perror_msg_and_die("can't run '%s'", command);
 279                 s[4] = '\0';
 280                 unsetenv(s);
 281                 free(s);
 282                 free(command);
 283         }
 284
 285         if (delete)
 286                 unlink(device_name);
 287 }
 288
 289 /* File callback for /sys/ traversal */
 290 static int fileAction(const char *fileName,
 291                       struct stat *statbuf ATTRIBUTE_UNUSED,
 292                       void *userData,
 293                       int depth ATTRIBUTE_UNUSED)
 294 {
 295         size_t len = strlen(fileName) - 4; /* can't underflow */
 296         char *scratch = userData;
 297
 298         /* len check is for paranoid reasons */
 299         if (strcmp(fileName + len, "/dev") || len >= PATH_MAX)
 300                 return FALSE;
 301
 302         strcpy(scratch, fileName);
 303         scratch[len] = '\0';
 304         make_device(scratch, 0);
 305
 306         return TRUE;
 307 }
 308
 309 /* Directory callback for /sys/ traversal */
 310 static int dirAction(const char *fileName ATTRIBUTE_UNUSED,
 311                       struct stat *statbuf ATTRIBUTE_UNUSED,
 312                       void *userData ATTRIBUTE_UNUSED,
 313                       int depth)
 314 {
 315         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 316 }
 317
 318 /* For the full gory details, see linux/Documentation/firmware_class/README
 319  *
 320  * Firmware loading works like this:
 321  * - kernel sets FIRMWARE env var
 322  * - userspace checks /lib/firmware/$FIRMWARE
 323  * - userspace waits for /sys/$DEVPATH/loading to appear
 324  * - userspace writes "1" to /sys/$DEVPATH/loading
 325  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 326  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 327  * - kernel loads firmware into device
 328  */
 329 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 330 {
 331         int cnt;
 332         int firmware_fd, loading_fd, data_fd;
 333
 334         /* check for /lib/firmware/$FIRMWARE */
 335         xchdir("/lib/firmware");
 336         firmware_fd = xopen(firmware, O_RDONLY);
 337
 338         /* in case we goto out ... */
 339         data_fd = -1;
 340
 341         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 342         xchdir(sysfs_path);
 343         for (cnt = 0; cnt < 30; ++cnt) {
 344                 loading_fd = open("loading", O_WRONLY);
 345                 if (loading_fd != -1)
 346                         goto loading;
 347                 sleep(1);
 348         }
 349         goto out;
 350
 351  loading:
 352         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 353         if (full_write(loading_fd, "1", 1) != 1)
 354                 goto out;
 355
 356         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 357         data_fd = open("data", O_WRONLY);
 358         if (data_fd == -1)
 359                 goto out;
 360         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 361
 362         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 363         if (cnt > 0)
 364                 full_write(loading_fd, "0", 1);
 365         else
 366                 full_write(loading_fd, "-1", 2);
 367
 368  out:
 369         if (ENABLE_FEATURE_CLEAN_UP) {
 370                 close(firmware_fd);
 371                 close(loading_fd);
 372                 close(data_fd);
 373         }
 374 }
 375
 376 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 377 int mdev_main(int argc, char **argv)
 378 {
 379         char *action;
 380         char *env_path;
 381         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 382
 383         xchdir("/dev");
 384
 385         if (argc == 2 && !strcmp(argv[1], "-s")) {
 386                 /* Scan:
 387                  * mdev -s
 388                  */
 389                 struct stat st;
 390
 391                 xstat("/", &st);
 392                 root_major = major(st.st_dev);
 393                 root_minor = minor(st.st_dev);
 394
 395                 recursive_action("/sys/block",
 396                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 397                         fileAction, dirAction, temp, 0);
 398
 399                 recursive_action("/sys/class",
 400                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 401                         fileAction, dirAction, temp, 0);
 402
 403         } else {
 404                 /* Hotplug:
 405                  * env ACTION=... DEVPATH=... mdev
 406                  * ACTION can be "add" or "remove"
 407                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 408                  */
 409                 action = getenv("ACTION");
 410                 env_path = getenv("DEVPATH");
 411                 if (!action || !env_path)
 412                         bb_show_usage();
 413
 414                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 415                 if (!strcmp(action, "remove"))
 416                         make_device(temp, 1);
 417                 else if (!strcmp(action, "add")) {
 418                         make_device(temp, 0);
 419
 420                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 421                                 char *fw = getenv("FIRMWARE");
 422                                 if (fw)
 423                                         load_firmware(fw, temp);
 424                         }
 425                 }
 426         }
 427
 428         if (ENABLE_FEATURE_CLEAN_UP)
 429                 RELEASE_CONFIG_BUFFER(temp);
 430
 431         return 0;
 432 }