util-linux/mdev.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * mdev - Mini udev for busybox
   4  *
   5  * Copyright 2005 Rob Landley <rob@landley.net>
   6  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   7  *
   8  * Licensed under GPLv2, see file LICENSE in this source tree.
   9  */
  10
  11 //config:config MDEV
  12 //config:       bool "mdev"
  13 //config:       default y
  14 //config:       select PLATFORM_LINUX
  15 //config:       help
  16 //config:         mdev is a mini-udev implementation for dynamically creating device
  17 //config:         nodes in the /dev directory.
  18 //config:
  19 //config:         For more information, please see docs/mdev.txt
  20 //config:
  21 //config:config FEATURE_MDEV_CONF
  22 //config:       bool "Support /etc/mdev.conf"
  23 //config:       default y
  24 //config:       depends on MDEV
  25 //config:       help
  26 //config:         Add support for the mdev config file to control ownership and
  27 //config:         permissions of the device nodes.
  28 //config:
  29 //config:         For more information, please see docs/mdev.txt
  30 //config:
  31 //config:config FEATURE_MDEV_RENAME
  32 //config:       bool "Support subdirs/symlinks"
  33 //config:       default y
  34 //config:       depends on FEATURE_MDEV_CONF
  35 //config:       help
  36 //config:         Add support for renaming devices and creating symlinks.
  37 //config:
  38 //config:         For more information, please see docs/mdev.txt
  39 //config:
  40 //config:config FEATURE_MDEV_RENAME_REGEXP
  41 //config:       bool "Support regular expressions substitutions when renaming device"
  42 //config:       default y
  43 //config:       depends on FEATURE_MDEV_RENAME
  44 //config:       help
  45 //config:         Add support for regular expressions substitutions when renaming
  46 //config:         device.
  47 //config:
  48 //config:config FEATURE_MDEV_EXEC
  49 //config:       bool "Support command execution at device addition/removal"
  50 //config:       default y
  51 //config:       depends on FEATURE_MDEV_CONF
  52 //config:       help
  53 //config:         This adds support for an optional field to /etc/mdev.conf for
  54 //config:         executing commands when devices are created/removed.
  55 //config:
  56 //config:         For more information, please see docs/mdev.txt
  57 //config:
  58 //config:config FEATURE_MDEV_LOAD_FIRMWARE
  59 //config:       bool "Support loading of firmwares"
  60 //config:       default y
  61 //config:       depends on MDEV
  62 //config:       help
  63 //config:         Some devices need to load firmware before they can be usable.
  64 //config:
  65 //config:         These devices will request userspace look up the files in
  66 //config:         /lib/firmware/ and if it exists, send it to the kernel for
  67 //config:         loading into the hardware.
  68
  69 //applet:IF_MDEV(APPLET(mdev, BB_DIR_SBIN, BB_SUID_DROP))
  70
  71 //kbuild:lib-$(CONFIG_MDEV) += mdev.o
  72
  73 //usage:#define mdev_trivial_usage
  74 //usage:       "[-s]"
  75 //usage:#define mdev_full_usage "\n\n"
  76 //usage:       "mdev -s is to be run during boot to scan /sys and populate /dev.\n"
  77 //usage:       "\n"
  78 //usage:       "Bare mdev is a kernel hotplug helper. To activate it:\n"
  79 //usage:       "        echo /sbin/mdev >/proc/sys/kernel/hotplug\n"
  80 //usage:        IF_FEATURE_MDEV_CONF(
  81 //usage:       "\n"
  82 //usage:       "It uses /etc/mdev.conf with lines\n"
  83 //usage:       "        [-]DEVNAME UID:GID PERM"
  84 //usage:                        IF_FEATURE_MDEV_RENAME(" [>|=PATH]|[!]")
  85 //usage:                        IF_FEATURE_MDEV_EXEC(" [@|$|*PROG]")
  86 //usage:       "\n"
  87 //usage:       "where DEVNAME is device name regex, @major,minor[-minor2], or\n"
  88 //usage:       "environment variable regex. A common use of the latter is\n"
  89 //usage:       "to load modules for hotplugged devices:\n"
  90 //usage:       "        $MODALIAS=.* 0:0 660 @modprobe \"$MODALIAS\"\n"
  91 //usage:        )
  92 //usage:       "\n"
  93 //usage:       "If /dev/mdev.seq file exists, mdev will wait for its value\n"
  94 //usage:       "to match $SEQNUM variable. This prevents plug/unplug races.\n"
  95 //usage:       "To activate this feature, create empty /dev/mdev.seq at boot."
  96 //usage:
  97 //usage:#define mdev_notes_usage ""
  98 //usage:        IF_FEATURE_MDEV_CONFIG(
  99 //usage:       "The mdev config file contains lines that look like:\n"
 100 //usage:       "  hd[a-z][0-9]* 0:3 660\n\n"
 101 //usage:       "That's device name (with regex match), uid:gid, and permissions.\n\n"
 102 //usage:        IF_FEATURE_MDEV_EXEC(
 103 //usage:       "Optionally, that can be followed (on the same line) by a special character\n"
 104 //usage:       "and a command line to run after creating/before deleting the corresponding\n"
 105 //usage:       "device(s). The environment variable $MDEV indicates the active device node\n"
 106 //usage:       "(which is useful if it's a regex match). For example:\n\n"
 107 //usage:       "  hdc root:cdrom 660  *ln -s $MDEV cdrom\n\n"
 108 //usage:       "The special characters are @ (run after creating), $ (run before deleting),\n"
 109 //usage:       "and * (run both after creating and before deleting). The commands run in\n"
 110 //usage:       "the /dev directory, and use system() which calls /bin/sh.\n\n"
 111 //usage:        )
 112 //usage:       "Config file parsing stops on the first matching line. If no config\n"
 113 //usage:       "entry is matched, devices are created with default 0:0 660. (Make\n"
 114 //usage:       "the last line match .* to override this.)\n\n"
 115 //usage:        )
 116
 117 #include "libbb.h"
 118 #include "xregex.h"
 119
 120 /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
 121  * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
 122  * contains "4:0\n". Directory name is taken as device name, path component
 123  * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty".
 124  * Then mdev creates the /dev/device_name node.
 125  * If /sys/class/.../dev file does not exist, mdev still may act
 126  * on this device: see "@|$|*command args..." parameter in config file.
 127  *
 128  * mdev w/o parameters is called as hotplug helper. It takes device
 129  * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts
 130  * maj,min from "/sys/$DEVPATH/dev" and also examines
 131  * $ACTION ("add"/"delete") and $FIRMWARE.
 132  *
 133  * If action is "add", mdev creates /dev/device_name similarly to mdev -s.
 134  * (todo: explain "delete" and $FIRMWARE)
 135  *
 136  * If /etc/mdev.conf exists, it may modify /dev/device_name's properties.
 137  * /etc/mdev.conf file format:
 138  *
 139  * [-][subsystem/]device  user:grp  mode  [>|=path]|[!] [@|$|*command args...]
 140  * [-]@maj,min[-min2]     user:grp  mode  [>|=path]|[!] [@|$|*command args...]
 141  * [-]$envvar=val         user:grp  mode  [>|=path]|[!] [@|$|*command args...]
 142  *
 143  * Leading minus in 1st field means "don't stop on this line", otherwise
 144  * search is stopped after the matching line is encountered.
 145  *
 146  * The device name or "subsystem/device" combo is matched against 1st field
 147  * (which is a regex), or maj,min is matched against 1st field,
 148  * or specified environment variable (as regex) is matched against 1st field.
 149  *
 150  * $envvar=val format is useful for loading modules for hot-plugged devices
 151  * which do not have driver loaded yet. In this case /sys/class/.../dev
 152  * does not exist, but $MODALIAS is set to needed module's name
 153  * (actually, an alias to it) by kernel. This rule instructs mdev
 154  * to load the module and exit:
 155  *    $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS"
 156  * The kernel will generate another hotplug event when /sys/class/.../dev
 157  * file appears.
 158  *
 159  * When line matches, the device node is created, chmod'ed and chown'ed,
 160  * moved to path, and if >path, a symlink to moved node is created,
 161  * all this if /sys/class/.../dev exists.
 162  *    Examples:
 163  *    =loop/      - moves to /dev/loop
 164  *    >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink
 165  *
 166  * Then "command args..." is executed (via sh -c 'command args...').
 167  * @:execute on creation, $:on deletion, *:on both.
 168  * This happens regardless of /sys/class/.../dev existence.
 169  */
 170
 171 struct rule {
 172         bool keep_matching;
 173         bool regex_compiled;
 174         bool regex_has_slash;
 175         mode_t mode;
 176         int maj, min0, min1;
 177         struct bb_uidgid_t ugid;
 178         char *envvar;
 179         char *ren_mov;
 180         IF_FEATURE_MDEV_EXEC(char *r_cmd;)
 181         regex_t match;
 182 };
 183
 184 struct globals {
 185         int root_major, root_minor;
 186         char *subsystem;
 187 #if ENABLE_FEATURE_MDEV_CONF
 188         const char *filename;
 189         parser_t *parser;
 190         struct rule **rule_vec;
 191         unsigned rule_idx;
 192 #endif
 193         struct rule cur_rule;
 194 } FIX_ALIASING;
 195 #define G (*(struct globals*)&bb_common_bufsiz1)
 196 #define INIT_G() do { } while (0)
 197
 198
 199 /* Prevent infinite loops in /sys symlinks */
 200 #define MAX_SYSFS_DEPTH 3
 201
 202 /* We use additional 64+ bytes in make_device() */
 203 #define SCRATCH_SIZE 80
 204
 205 #if 0
 206 # define dbg(...) bb_error_msg(__VA_ARGS__)
 207 #else
 208 # define dbg(...) ((void)0)
 209 #endif
 210
 211
 212 #if ENABLE_FEATURE_MDEV_CONF
 213
 214 static void make_default_cur_rule(void)
 215 {
 216         memset(&G.cur_rule, 0, sizeof(G.cur_rule));
 217         G.cur_rule.maj = -1; /* "not a @major,minor rule" */
 218         G.cur_rule.mode = 0660;
 219 }
 220
 221 static void clean_up_cur_rule(void)
 222 {
 223         free(G.cur_rule.envvar);
 224         if (G.cur_rule.regex_compiled)
 225                 regfree(&G.cur_rule.match);
 226         free(G.cur_rule.ren_mov);
 227         IF_FEATURE_MDEV_EXEC(free(G.cur_rule.r_cmd);)
 228         make_default_cur_rule();
 229 }
 230
 231 static void parse_next_rule(void)
 232 {
 233         /* Note: on entry, G.cur_rule is set to default */
 234         while (1) {
 235                 char *tokens[4];
 236                 char *val;
 237
 238                 if (!config_read(G.parser, tokens, 4, 3, "# \t", PARSE_NORMAL))
 239                         break;
 240
 241                 /* Fields: [-]regex uid:gid mode [alias] [cmd] */
 242                 dbg("token1:'%s'", tokens[1]);
 243
 244                 /* 1st field */
 245                 val = tokens[0];
 246                 G.cur_rule.keep_matching = ('-' == val[0]);
 247                 val += G.cur_rule.keep_matching; /* swallow leading dash */
 248                 if (val[0] == '@') {
 249                         /* @major,minor[-minor2] */
 250                         /* (useful when name is ambiguous:
 251                          * "/sys/class/usb/lp0" and
 252                          * "/sys/class/printer/lp0")
 253                          */
 254                         int sc = sscanf(val, "@%u,%u-%u", &G.cur_rule.maj, &G.cur_rule.min0, &G.cur_rule.min1);
 255                         if (sc < 2 || G.cur_rule.maj < 0) {
 256                                 bb_error_msg("bad @maj,min on line %d", G.parser->lineno);
 257                                 goto next_rule;
 258                         }
 259                         if (sc == 2)
 260                                 G.cur_rule.min1 = G.cur_rule.min0;
 261                 } else {
 262                         if (val[0] == '$') {
 263                                 char *eq = strchr(++val, '=');
 264                                 if (!eq) {
 265                                         bb_error_msg("bad $envvar=regex on line %d", G.parser->lineno);
 266                                         goto next_rule;
 267                                 }
 268                                 G.cur_rule.envvar = xstrndup(val, eq - val);
 269                                 val = eq + 1;
 270                         }
 271                         xregcomp(&G.cur_rule.match, val, REG_EXTENDED);
 272                         G.cur_rule.regex_compiled = 1;
 273                         G.cur_rule.regex_has_slash = (strchr(val, '/') != NULL);
 274                 }
 275
 276                 /* 2nd field: uid:gid - device ownership */
 277                 if (get_uidgid(&G.cur_rule.ugid, tokens[1], /*allow_numeric:*/ 1) == 0) {
 278                         bb_error_msg("unknown user/group '%s' on line %d", tokens[1], G.parser->lineno);
 279                         goto next_rule;
 280                 }
 281
 282                 /* 3rd field: mode - device permissions */
 283                 bb_parse_mode(tokens[2], &G.cur_rule.mode);
 284
 285                 /* 4th field (opt): ">|=alias" or "!" to not create the node */
 286                 val = tokens[3];
 287                 if (ENABLE_FEATURE_MDEV_RENAME && val && strchr(">=!", val[0])) {
 288                         char *s = skip_non_whitespace(val);
 289                         G.cur_rule.ren_mov = xstrndup(val, s - val);
 290                         val = skip_whitespace(s);
 291                 }
 292
 293                 if (ENABLE_FEATURE_MDEV_EXEC && val && val[0]) {
 294                         const char *s = "$@*";
 295                         const char *s2 = strchr(s, val[0]);
 296                         if (!s2) {
 297                                 bb_error_msg("bad line %u", G.parser->lineno);
 298                                 goto next_rule;
 299                         }
 300                         IF_FEATURE_MDEV_EXEC(G.cur_rule.r_cmd = xstrdup(val);)
 301                 }
 302
 303                 return;
 304  next_rule:
 305                 clean_up_cur_rule();
 306         } /* while (config_read) */
 307
 308         dbg("config_close(G.parser)");
 309         config_close(G.parser);
 310         G.parser = NULL;
 311
 312         return;
 313 }
 314
 315 /* If mdev -s, we remember rules in G.rule_vec[].
 316  * Otherwise, there is no point in doing it, and we just
 317  * save only one parsed rule in G.cur_rule.
 318  */
 319 static const struct rule *next_rule(void)
 320 {
 321         struct rule *rule;
 322
 323         /* Open conf file if we didn't do it yet */
 324         if (!G.parser && G.filename) {
 325                 dbg("config_open('%s')", G.filename);
 326                 G.parser = config_open2(G.filename, fopen_for_read);
 327                 G.filename = NULL;
 328         }
 329
 330         if (G.rule_vec) {
 331                 /* mdev -s */
 332                 /* Do we have rule parsed already? */
 333                 if (G.rule_vec[G.rule_idx]) {
 334                         dbg("< G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 335                         return G.rule_vec[G.rule_idx++];
 336                 }
 337                 make_default_cur_rule();
 338         } else {
 339                 /* not mdev -s */
 340                 clean_up_cur_rule();
 341         }
 342
 343         /* Parse one more rule if file isn't fully read */
 344         rule = &G.cur_rule;
 345         if (G.parser) {
 346                 parse_next_rule();
 347                 if (G.rule_vec) { /* mdev -s */
 348                         rule = memcpy(xmalloc(sizeof(G.cur_rule)), &G.cur_rule, sizeof(G.cur_rule));
 349                         G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx);
 350                         G.rule_vec[G.rule_idx++] = rule;
 351                         dbg("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
 352                 }
 353         }
 354
 355         return rule;
 356 }
 357
 358 #else
 359
 360 # define next_rule() (&G.cur_rule)
 361
 362 #endif
 363
 364 /* Builds an alias path.
 365  * This function potentionally reallocates the alias parameter.
 366  * Only used for ENABLE_FEATURE_MDEV_RENAME
 367  */
 368 static char *build_alias(char *alias, const char *device_name)
 369 {
 370         char *dest;
 371
 372         /* ">bar/": rename to bar/device_name */
 373         /* ">bar[/]baz": rename to bar[/]baz */
 374         dest = strrchr(alias, '/');
 375         if (dest) { /* ">bar/[baz]" ? */
 376                 *dest = '\0'; /* mkdir bar */
 377                 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 378                 *dest = '/';
 379                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 380                         dest = alias;
 381                         alias = concat_path_file(alias, device_name);
 382                         free(dest);
 383                 }
 384         }
 385
 386         return alias;
 387 }
 388
 389 /* mknod in /dev based on a path like "/sys/block/hda/hda1"
 390  * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
 391  * after NUL, but we promise to not mangle (IOW: to restore if needed)
 392  * path string.
 393  * NB2: "mdev -s" may call us many times, do not leak memory/fds!
 394  */
 395 static void make_device(char *path, int delete)
 396 {
 397         char *device_name, *subsystem_slash_devname;
 398         int major, minor, type, len;
 399
 400         dbg("%s('%s', delete:%d)", __func__, path, delete);
 401
 402         /* Try to read major/minor string.  Note that the kernel puts \n after
 403          * the data, so we don't need to worry about null terminating the string
 404          * because sscanf() will stop at the first nondigit, which \n is.
 405          * We also depend on path having writeable space after it.
 406          */
 407         major = -1;
 408         if (!delete) {
 409                 char *dev_maj_min = path + strlen(path);
 410
 411                 strcpy(dev_maj_min, "/dev");
 412                 len = open_read_close(path, dev_maj_min + 1, 64);
 413                 *dev_maj_min = '\0';
 414                 if (len < 1) {
 415                         if (!ENABLE_FEATURE_MDEV_EXEC)
 416                                 return;
 417                         /* no "dev" file, but we can still run scripts
 418                          * based on device name */
 419                 } else if (sscanf(++dev_maj_min, "%u:%u", &major, &minor) != 2) {
 420                         major = -1;
 421                 }
 422         }
 423         /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
 424
 425         /* Determine device name, type, major and minor */
 426         device_name = (char*) bb_basename(path);
 427         /* http://kernel.org/doc/pending/hotplug.txt says that only
 428          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
 429          * But since 2.6.25 block devices are also in /sys/class/block.
 430          * We use strstr("/block/") to forestall future surprises. */
 431         type = S_IFCHR;
 432         if (strstr(path, "/block/") || (G.subsystem && strncmp(G.subsystem, "block", 5) == 0))
 433                 type = S_IFBLK;
 434
 435         /* Make path point to "subsystem/device_name" */
 436         subsystem_slash_devname = NULL;
 437         /* Check for coldplug invocations first */
 438         if (strncmp(path, "/sys/block/", 11) == 0) /* legacy case */
 439                 path += sizeof("/sys/") - 1;
 440         else if (strncmp(path, "/sys/class/", 11) == 0)
 441                 path += sizeof("/sys/class/") - 1;
 442         else {
 443                 /* Example of a hotplug invocation:
 444                  * SUBSYSTEM="block"
 445                  * DEVPATH="/sys" + "/devices/virtual/mtd/mtd3/mtdblock3"
 446                  * ("/sys" is added by mdev_main)
 447                  * - path does not contain subsystem
 448                  */
 449                 subsystem_slash_devname = concat_path_file(G.subsystem, device_name);
 450                 path = subsystem_slash_devname;
 451         }
 452
 453 #if ENABLE_FEATURE_MDEV_CONF
 454         G.rule_idx = 0; /* restart from the beginning (think mdev -s) */
 455 #endif
 456         for (;;) {
 457                 const char *str_to_match;
 458                 regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 459                 char *command;
 460                 char *alias;
 461                 char aliaslink = aliaslink; /* for compiler */
 462                 const char *node_name;
 463                 const struct rule *rule;
 464
 465                 str_to_match = "";
 466
 467                 rule = next_rule();
 468
 469 #if ENABLE_FEATURE_MDEV_CONF
 470                 if (rule->maj >= 0) {  /* @maj,min rule */
 471                         if (major != rule->maj)
 472                                 continue;
 473                         if (minor < rule->min0 || minor > rule->min1)
 474                                 continue;
 475                         memset(off, 0, sizeof(off));
 476                         goto rule_matches;
 477                 }
 478                 if (rule->envvar) { /* $envvar=regex rule */
 479                         str_to_match = getenv(rule->envvar);
 480                         dbg("getenv('%s'):'%s'", rule->envvar, str_to_match);
 481                         if (!str_to_match)
 482                                 continue;
 483                 } else {
 484                         /* regex to match [subsystem/]device_name */
 485                         str_to_match = (rule->regex_has_slash ? path : device_name);
 486                 }
 487
 488                 if (rule->regex_compiled) {
 489                         int regex_match = regexec(&rule->match, str_to_match, ARRAY_SIZE(off), off, 0);
 490                         dbg("regex_match for '%s':%d", str_to_match, regex_match);
 491                         //bb_error_msg("matches:");
 492                         //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 493                         //      if (off[i].rm_so < 0) continue;
 494                         //      bb_error_msg("match %d: '%.*s'\n", i,
 495                         //              (int)(off[i].rm_eo - off[i].rm_so),
 496                         //              device_name + off[i].rm_so);
 497                         //}
 498
 499                         if (regex_match != 0
 500                         /* regexec returns whole pattern as "range" 0 */
 501                          || off[0].rm_so != 0
 502                          || (int)off[0].rm_eo != (int)strlen(str_to_match)
 503                         ) {
 504                                 continue; /* this rule doesn't match */
 505                         }
 506                 }
 507                 /* else: it's final implicit "match-all" rule */
 508 #endif
 509
 510  rule_matches:
 511                 dbg("rule matched");
 512
 513                 /* Build alias name */
 514                 alias = NULL;
 515                 if (ENABLE_FEATURE_MDEV_RENAME && rule->ren_mov) {
 516                         aliaslink = rule->ren_mov[0];
 517                         if (aliaslink == '!') {
 518                                 /* "!": suppress node creation/deletion */
 519                                 major = -2;
 520                         }
 521                         else if (aliaslink == '>' || aliaslink == '=') {
 522                                 if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
 523                                         char *s;
 524                                         char *p;
 525                                         unsigned n;
 526
 527                                         /* substitute %1..9 with off[1..9], if any */
 528                                         n = 0;
 529                                         s = rule->ren_mov;
 530                                         while (*s)
 531                                                 if (*s++ == '%')
 532                                                         n++;
 533
 534                                         p = alias = xzalloc(strlen(rule->ren_mov) + n * strlen(str_to_match));
 535                                         s = rule->ren_mov + 1;
 536                                         while (*s) {
 537                                                 *p = *s;
 538                                                 if ('%' == *s) {
 539                                                         unsigned i = (s[1] - '0');
 540                                                         if (i <= 9 && off[i].rm_so >= 0) {
 541                                                                 n = off[i].rm_eo - off[i].rm_so;
 542                                                                 strncpy(p, str_to_match + off[i].rm_so, n);
 543                                                                 p += n - 1;
 544                                                                 s++;
 545                                                         }
 546                                                 }
 547                                                 p++;
 548                                                 s++;
 549                                         }
 550                                 } else {
 551                                         alias = xstrdup(rule->ren_mov + 1);
 552                                 }
 553                         }
 554                 }
 555                 dbg("alias:'%s'", alias);
 556
 557                 command = NULL;
 558                 IF_FEATURE_MDEV_EXEC(command = rule->r_cmd;)
 559                 if (command) {
 560                         const char *s = "$@*";
 561                         const char *s2 = strchr(s, command[0]);
 562
 563                         /* Are we running this command now?
 564                          * Run $cmd on delete, @cmd on create, *cmd on both
 565                          */
 566                         if (s2 - s != delete) {
 567                                 /* We are here if: '*',
 568                                  * or: '@' and delete = 0,
 569                                  * or: '$' and delete = 1
 570                                  */
 571                                 command++;
 572                         } else {
 573                                 command = NULL;
 574                         }
 575                 }
 576                 dbg("command:'%s'", command);
 577
 578                 /* "Execute" the line we found */
 579                 node_name = device_name;
 580                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 581                         node_name = alias = build_alias(alias, device_name);
 582                         dbg("alias2:'%s'", alias);
 583                 }
 584
 585                 if (!delete && major >= 0) {
 586                         dbg("mknod('%s',%o,(%d,%d))", node_name, rule->mode | type, major, minor);
 587                         if (mknod(node_name, rule->mode | type, makedev(major, minor)) && errno != EEXIST)
 588                                 bb_perror_msg("can't create '%s'", node_name);
 589                         if (major == G.root_major && minor == G.root_minor)
 590                                 symlink(node_name, "root");
 591                         if (ENABLE_FEATURE_MDEV_CONF) {
 592                                 chmod(node_name, rule->mode);
 593                                 chown(node_name, rule->ugid.uid, rule->ugid.gid);
 594                         }
 595                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 596                                 if (aliaslink == '>')
 597                                         symlink(node_name, device_name);
 598                         }
 599                 }
 600
 601                 if (ENABLE_FEATURE_MDEV_EXEC && command) {
 602                         /* setenv will leak memory, use putenv/unsetenv/free */
 603                         char *s = xasprintf("%s=%s", "MDEV", node_name);
 604                         char *s1 = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
 605                         putenv(s);
 606                         putenv(s1);
 607                         if (system(command) == -1)
 608                                 bb_perror_msg("can't run '%s'", command);
 609                         bb_unsetenv_and_free(s1);
 610                         bb_unsetenv_and_free(s);
 611                 }
 612
 613                 if (delete && major >= -1) {
 614                         if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 615                                 if (aliaslink == '>')
 616                                         unlink(device_name);
 617                         }
 618                         unlink(node_name);
 619                 }
 620
 621                 if (ENABLE_FEATURE_MDEV_RENAME)
 622                         free(alias);
 623
 624                 /* We found matching line.
 625                  * Stop unless it was prefixed with '-'
 626                  */
 627                 if (!ENABLE_FEATURE_MDEV_CONF || !rule->keep_matching)
 628                         break;
 629         } /* for (;;) */
 630
 631         free(subsystem_slash_devname);
 632 }
 633
 634 /* File callback for /sys/ traversal */
 635 static int FAST_FUNC fileAction(const char *fileName,
 636                 struct stat *statbuf UNUSED_PARAM,
 637                 void *userData,
 638                 int depth UNUSED_PARAM)
 639 {
 640         size_t len = strlen(fileName) - 4; /* can't underflow */
 641         char *scratch = userData;
 642
 643         /* len check is for paranoid reasons */
 644         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 645                 return FALSE;
 646
 647         strcpy(scratch, fileName);
 648         scratch[len] = '\0';
 649         make_device(scratch, /*delete:*/ 0);
 650
 651         return TRUE;
 652 }
 653
 654 /* Directory callback for /sys/ traversal */
 655 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 656                 struct stat *statbuf UNUSED_PARAM,
 657                 void *userData UNUSED_PARAM,
 658                 int depth)
 659 {
 660         /* Extract device subsystem -- the name of the directory
 661          * under /sys/class/ */
 662         if (1 == depth) {
 663                 free(G.subsystem);
 664                 G.subsystem = strrchr(fileName, '/');
 665                 if (G.subsystem)
 666                         G.subsystem = xstrdup(G.subsystem + 1);
 667         }
 668
 669         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 670 }
 671
 672 /* For the full gory details, see linux/Documentation/firmware_class/README
 673  *
 674  * Firmware loading works like this:
 675  * - kernel sets FIRMWARE env var
 676  * - userspace checks /lib/firmware/$FIRMWARE
 677  * - userspace waits for /sys/$DEVPATH/loading to appear
 678  * - userspace writes "1" to /sys/$DEVPATH/loading
 679  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 680  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 681  * - kernel loads firmware into device
 682  */
 683 static void load_firmware(const char *firmware, const char *sysfs_path)
 684 {
 685         int cnt;
 686         int firmware_fd, loading_fd, data_fd;
 687
 688         /* check for /lib/firmware/$FIRMWARE */
 689         xchdir("/lib/firmware");
 690         firmware_fd = xopen(firmware, O_RDONLY);
 691
 692         /* in case we goto out ... */
 693         data_fd = -1;
 694
 695         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 696         xchdir(sysfs_path);
 697         for (cnt = 0; cnt < 30; ++cnt) {
 698                 loading_fd = open("loading", O_WRONLY);
 699                 if (loading_fd != -1)
 700                         goto loading;
 701                 sleep(1);
 702         }
 703         goto out;
 704
 705  loading:
 706         /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
 707         if (full_write(loading_fd, "1", 1) != 1)
 708                 goto out;
 709
 710         /* load firmware into /sys/$DEVPATH/data */
 711         data_fd = open("data", O_WRONLY);
 712         if (data_fd == -1)
 713                 goto out;
 714         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 715
 716         /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */
 717         if (cnt > 0)
 718                 full_write(loading_fd, "0", 1);
 719         else
 720                 full_write(loading_fd, "-1", 2);
 721
 722  out:
 723         if (ENABLE_FEATURE_CLEAN_UP) {
 724                 close(firmware_fd);
 725                 close(loading_fd);
 726                 close(data_fd);
 727         }
 728 }
 729
 730 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 731 int mdev_main(int argc UNUSED_PARAM, char **argv)
 732 {
 733         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 734
 735         INIT_G();
 736
 737 #if ENABLE_FEATURE_MDEV_CONF
 738         G.filename = "/etc/mdev.conf";
 739 #endif
 740
 741         /* We can be called as hotplug helper */
 742         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 743         bb_sanitize_stdio();
 744
 745         /* Force the configuration file settings exactly */
 746         umask(0);
 747
 748         xchdir("/dev");
 749
 750         if (argv[1] && strcmp(argv[1], "-s") == 0) {
 751                 /* Scan:
 752                  * mdev -s
 753                  */
 754                 struct stat st;
 755
 756 #if ENABLE_FEATURE_MDEV_CONF
 757                 /* Same as xrealloc_vector(NULL, 4, 0): */
 758                 G.rule_vec = xzalloc((1 << 4) * sizeof(*G.rule_vec));
 759 #endif
 760                 xstat("/", &st);
 761                 G.root_major = major(st.st_dev);
 762                 G.root_minor = minor(st.st_dev);
 763
 764                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 765                  * /sys/block/loop* (for example) are symlinks to dirs,
 766                  * not real directories.
 767                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 768                  * but we can't enforce that on users)
 769                  */
 770                 if (access("/sys/class/block", F_OK) != 0) {
 771                         /* Scan obsolete /sys/block only if /sys/class/block
 772                          * doesn't exist. Otherwise we'll have dupes.
 773                          * Also, do not complain if it doesn't exist.
 774                          * Some people configure kernel to have no blockdevs.
 775                          */
 776                         recursive_action("/sys/block",
 777                                 ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
 778                                 fileAction, dirAction, temp, 0);
 779                 }
 780                 recursive_action("/sys/class",
 781                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 782                         fileAction, dirAction, temp, 0);
 783         } else {
 784                 char *fw;
 785                 char *seq;
 786                 char *action;
 787                 char *env_path;
 788                 static const char keywords[] ALIGN1 = "remove\0add\0";
 789                 enum { OP_remove = 0, OP_add };
 790                 smalluint op;
 791
 792                 /* Hotplug:
 793                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
 794                  * ACTION can be "add" or "remove"
 795                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 796                  */
 797                 action = getenv("ACTION");
 798                 env_path = getenv("DEVPATH");
 799                 G.subsystem = getenv("SUBSYSTEM");
 800                 if (!action || !env_path /*|| !G.subsystem*/)
 801                         bb_show_usage();
 802                 fw = getenv("FIRMWARE");
 803                 op = index_in_strings(keywords, action);
 804                 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 805                  * If it does not match, earlier mdev is running
 806                  * in parallel, and we need to wait */
 807                 seq = getenv("SEQNUM");
 808                 if (seq) {
 809                         int timeout = 2000 / 32; /* 2000 msec */
 810                         do {
 811                                 int seqlen;
 812                                 char seqbuf[sizeof(int)*3 + 2];
 813
 814                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 815                                 if (seqlen < 0) {
 816                                         seq = NULL;
 817                                         break;
 818                                 }
 819                                 seqbuf[seqlen] = '\0';
 820                                 if (seqbuf[0] == '\n' /* seed file? */
 821                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 822                                 ) {
 823                                         break;
 824                                 }
 825                                 usleep(32*1000);
 826                         } while (--timeout);
 827                 }
 828
 829                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 830                 if (op == OP_remove) {
 831                         /* Ignoring "remove firmware". It was reported
 832                          * to happen and to cause erroneous deletion
 833                          * of device nodes. */
 834                         if (!fw)
 835                                 make_device(temp, /*delete:*/ 1);
 836                 }
 837                 else if (op == OP_add) {
 838                         make_device(temp, /*delete:*/ 0);
 839                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 840                                 if (fw)
 841                                         load_firmware(fw, temp);
 842                         }
 843                 }
 844
 845                 if (seq) {
 846                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 847                 }
 848         }
 849
 850         if (ENABLE_FEATURE_CLEAN_UP)
 851                 RELEASE_CONFIG_BUFFER(temp);
 852
 853         return EXIT_SUCCESS;
 854 }