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