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 globals {
 172         int root_major, root_minor;
 173         char *subsystem;
 174 } FIX_ALIASING;
 175 #define G (*(struct globals*)&bb_common_bufsiz1)
 176
 177 /* Prevent infinite loops in /sys symlinks */
 178 #define MAX_SYSFS_DEPTH 3
 179
 180 /* We use additional 64+ bytes in make_device() */
 181 #define SCRATCH_SIZE 80
 182
 183 /* Builds an alias path.
 184  * This function potentionally reallocates the alias parameter.
 185  * Only used for ENABLE_FEATURE_MDEV_RENAME
 186  */
 187 static char *build_alias(char *alias, const char *device_name)
 188 {
 189         char *dest;
 190
 191         /* ">bar/": rename to bar/device_name */
 192         /* ">bar[/]baz": rename to bar[/]baz */
 193         dest = strrchr(alias, '/');
 194         if (dest) { /* ">bar/[baz]" ? */
 195                 *dest = '\0'; /* mkdir bar */
 196                 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
 197                 *dest = '/';
 198                 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
 199                         dest = alias;
 200                         alias = concat_path_file(alias, device_name);
 201                         free(dest);
 202                 }
 203         }
 204
 205         return alias;
 206 }
 207
 208 /* mknod in /dev based on a path like "/sys/block/hda/hda1"
 209  * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
 210  * after NUL, but we promise to not mangle (IOW: to restore if needed)
 211  * path string.
 212  * NB2: "mdev -s" may call us many times, do not leak memory/fds!
 213  */
 214 static void make_device(char *path, int delete)
 215 {
 216         char *device_name, *subsystem_slash_devname;
 217         int major, minor, type, len;
 218         mode_t mode;
 219         parser_t *parser;
 220
 221         /* Try to read major/minor string.  Note that the kernel puts \n after
 222          * the data, so we don't need to worry about null terminating the string
 223          * because sscanf() will stop at the first nondigit, which \n is.
 224          * We also depend on path having writeable space after it.
 225          */
 226         major = -1;
 227         if (!delete) {
 228                 char *dev_maj_min = path + strlen(path);
 229
 230                 strcpy(dev_maj_min, "/dev");
 231                 len = open_read_close(path, dev_maj_min + 1, 64);
 232                 *dev_maj_min = '\0';
 233                 if (len < 1) {
 234                         if (!ENABLE_FEATURE_MDEV_EXEC)
 235                                 return;
 236                         /* no "dev" file, but we can still run scripts
 237                          * based on device name */
 238                 } else if (sscanf(++dev_maj_min, "%u:%u", &major, &minor) != 2) {
 239                         major = -1;
 240                 }
 241         }
 242         /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
 243
 244         /* Determine device name, type, major and minor */
 245         device_name = (char*) bb_basename(path);
 246         /* http://kernel.org/doc/pending/hotplug.txt says that only
 247          * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
 248          * But since 2.6.25 block devices are also in /sys/class/block.
 249          * We use strstr("/block/") to forestall future surprises. */
 250         type = S_IFCHR;
 251         if (strstr(path, "/block/") || (G.subsystem && strncmp(G.subsystem, "block", 5) == 0))
 252                 type = S_IFBLK;
 253
 254         /* Make path point to "subsystem/device_name" */
 255         subsystem_slash_devname = NULL;
 256         /* Check for coldplug invocations first */
 257         if (strncmp(path, "/sys/block/", 11) == 0) /* legacy case */
 258                 path += sizeof("/sys/") - 1;
 259         else if (strncmp(path, "/sys/class/", 11) == 0)
 260                 path += sizeof("/sys/class/") - 1;
 261         else {
 262                 /* Example of a hotplug invocation:
 263                  * SUBSYSTEM="block"
 264                  * DEVPATH="/sys" + "/devices/virtual/mtd/mtd3/mtdblock3"
 265                  * ("/sys" is added by mdev_main)
 266                  * - path does not contain subsystem
 267                  */
 268                 subsystem_slash_devname = concat_path_file(G.subsystem, device_name);
 269                 path = subsystem_slash_devname;
 270         }
 271
 272         /* If we have config file, look up user settings */
 273         if (ENABLE_FEATURE_MDEV_CONF)
 274                 parser = config_open2("/etc/mdev.conf", fopen_for_read);
 275
 276         do {
 277                 int keep_matching;
 278                 struct bb_uidgid_t ugid;
 279                 char *tokens[4];
 280                 char *command = NULL;
 281                 char *alias = NULL;
 282                 char aliaslink = aliaslink; /* for compiler */
 283
 284                 /* Defaults in case we won't match any line */
 285                 ugid.uid = ugid.gid = 0;
 286                 keep_matching = 0;
 287                 mode = 0660;
 288
 289                 if (ENABLE_FEATURE_MDEV_CONF
 290                  && config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)
 291                 ) {
 292                         char *val;
 293                         char *str_to_match;
 294                         regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
 295
 296                         val = tokens[0];
 297                         keep_matching = ('-' == val[0]);
 298                         val += keep_matching; /* swallow leading dash */
 299
 300                         /* Match against either "subsystem/device_name"
 301                          * or "device_name" alone */
 302                         str_to_match = strchr(val, '/') ? path : device_name;
 303
 304                         /* Fields: regex uid:gid mode [alias] [cmd] */
 305
 306                         if (val[0] == '@') {
 307                                 /* @major,minor[-minor2] */
 308                                 /* (useful when name is ambiguous:
 309                                  * "/sys/class/usb/lp0" and
 310                                  * "/sys/class/printer/lp0") */
 311                                 int cmaj, cmin0, cmin1, sc;
 312                                 if (major < 0)
 313                                         continue; /* no dev, no match */
 314                                 sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
 315                                 if (sc < 1
 316                                  || major != cmaj
 317                                  || (sc == 2 && minor != cmin0)
 318                                  || (sc == 3 && (minor < cmin0 || minor > cmin1))
 319                                 ) {
 320                                         continue; /* this line doesn't match */
 321                                 }
 322                                 goto line_matches;
 323                         }
 324                         if (val[0] == '$') {
 325                                 /* regex to match an environment variable */
 326                                 char *eq = strchr(++val, '=');
 327                                 if (!eq)
 328                                         continue;
 329                                 *eq = '\0';
 330                                 str_to_match = getenv(val);
 331                                 if (!str_to_match)
 332                                         continue;
 333                                 str_to_match -= strlen(val) + 1;
 334                                 *eq = '=';
 335                         }
 336                         /* else: regex to match [subsystem/]device_name */
 337
 338                         {
 339                                 regex_t match;
 340                                 int result;
 341
 342                                 xregcomp(&match, val, REG_EXTENDED);
 343                                 result = regexec(&match, str_to_match, ARRAY_SIZE(off), off, 0);
 344                                 regfree(&match);
 345                                 //bb_error_msg("matches:");
 346                                 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
 347                                 //      if (off[i].rm_so < 0) continue;
 348                                 //      bb_error_msg("match %d: '%.*s'\n", i,
 349                                 //              (int)(off[i].rm_eo - off[i].rm_so),
 350                                 //              device_name + off[i].rm_so);
 351                                 //}
 352
 353                                 /* If no match, skip rest of line */
 354                                 /* (regexec returns whole pattern as "range" 0) */
 355                                 if (result
 356                                  || off[0].rm_so
 357                                  || ((int)off[0].rm_eo != (int)strlen(str_to_match))
 358                                 ) {
 359                                         continue; /* this line doesn't match */
 360                                 }
 361                         }
 362  line_matches:
 363                         /* This line matches. Stop parsing after parsing
 364                          * the rest the line unless keep_matching == 1 */
 365
 366                         /* 2nd field: uid:gid - device ownership */
 367                         if (get_uidgid(&ugid, tokens[1], /*allow_numeric:*/ 1) == 0)
 368                                 bb_error_msg("unknown user/group %s on line %d", tokens[1], parser->lineno);
 369
 370                         /* 3rd field: mode - device permissions */
 371                         bb_parse_mode(tokens[2], &mode);
 372
 373                         val = tokens[3];
 374                         /* 4th field (opt): ">|=alias" or "!" to not create the node */
 375
 376                         if (ENABLE_FEATURE_MDEV_RENAME && val) {
 377                                 char *a, *s, *st;
 378
 379                                 a = val;
 380                                 s = strchrnul(val, ' ');
 381                                 st = strchrnul(val, '\t');
 382                                 if (st < s)
 383                                         s = st;
 384                                 st = (s[0] && s[1]) ? s+1 : NULL;
 385
 386                                 aliaslink = a[0];
 387                                 if (aliaslink == '!' && s == a+1) {
 388                                         val = st;
 389                                         /* "!": suppress node creation/deletion */
 390                                         major = -2;
 391                                 }
 392                                 else if (aliaslink == '>' || aliaslink == '=') {
 393                                         val = st;
 394                                         s[0] = '\0';
 395                                         if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
 396                                                 char *p;
 397                                                 unsigned i, n;
 398
 399                                                 /* substitute %1..9 with off[1..9], if any */
 400                                                 n = 0;
 401                                                 s = a;
 402                                                 while (*s)
 403                                                         if (*s++ == '%')
 404                                                                 n++;
 405
 406                                                 p = alias = xzalloc(strlen(a) + n * strlen(str_to_match));
 407                                                 s = a + 1;
 408                                                 while (*s) {
 409                                                         *p = *s;
 410                                                         if ('%' == *s) {
 411                                                                 i = (s[1] - '0');
 412                                                                 if (i <= 9 && off[i].rm_so >= 0) {
 413                                                                         n = off[i].rm_eo - off[i].rm_so;
 414                                                                         strncpy(p, str_to_match + off[i].rm_so, n);
 415                                                                         p += n - 1;
 416                                                                         s++;
 417                                                                 }
 418                                                         }
 419                                                         p++;
 420                                                         s++;
 421                                                 }
 422                                         } else {
 423                                                 alias = xstrdup(a + 1);
 424                                         }
 425                                 }
 426                         }
 427
 428                         if (ENABLE_FEATURE_MDEV_EXEC && val) {
 429                                 const char *s = "$@*";
 430                                 const char *s2 = strchr(s, val[0]);
 431
 432                                 if (!s2) {
 433                                         bb_error_msg("bad line %u", parser->lineno);
 434                                         if (ENABLE_FEATURE_MDEV_RENAME)
 435                                                 free(alias);
 436                                         continue;
 437                                 }
 438
 439                                 /* Are we running this command now?
 440                                  * Run $cmd on delete, @cmd on create, *cmd on both
 441                                  */
 442                                 if (s2 - s != delete) {
 443                                         /* We are here if: '*',
 444                                          * or: '@' and delete = 0,
 445                                          * or: '$' and delete = 1
 446                                          */
 447                                         command = xstrdup(val + 1);
 448                                 }
 449                         }
 450                 }
 451
 452                 /* End of field parsing */
 453
 454                 /* "Execute" the line we found */
 455                 {
 456                         const char *node_name;
 457
 458                         node_name = device_name;
 459                         if (ENABLE_FEATURE_MDEV_RENAME && alias)
 460                                 node_name = alias = build_alias(alias, device_name);
 461
 462                         if (!delete && major >= 0) {
 463                                 if (mknod(node_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 464                                         bb_perror_msg("can't create '%s'", node_name);
 465                                 if (major == G.root_major && minor == G.root_minor)
 466                                         symlink(node_name, "root");
 467                                 if (ENABLE_FEATURE_MDEV_CONF) {
 468                                         chmod(node_name, mode);
 469                                         chown(node_name, ugid.uid, ugid.gid);
 470                                 }
 471                                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 472                                         if (aliaslink == '>')
 473                                                 symlink(node_name, device_name);
 474                                 }
 475                         }
 476
 477                         if (ENABLE_FEATURE_MDEV_EXEC && command) {
 478                                 /* setenv will leak memory, use putenv/unsetenv/free */
 479                                 char *s = xasprintf("%s=%s", "MDEV", node_name);
 480                                 char *s1 = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
 481                                 putenv(s);
 482                                 putenv(s1);
 483                                 if (system(command) == -1)
 484                                         bb_perror_msg("can't run '%s'", command);
 485                                 bb_unsetenv_and_free(s1);
 486                                 bb_unsetenv_and_free(s);
 487                                 free(command);
 488                         }
 489
 490                         if (delete && major >= -1) {
 491                                 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
 492                                         if (aliaslink == '>')
 493                                                 unlink(device_name);
 494                                 }
 495                                 unlink(node_name);
 496                         }
 497
 498                         if (ENABLE_FEATURE_MDEV_RENAME)
 499                                 free(alias);
 500                 }
 501
 502                 /* We found matching line.
 503                  * Stop unless it was prefixed with '-' */
 504                 if (ENABLE_FEATURE_MDEV_CONF && !keep_matching)
 505                         break;
 506
 507         /* end of "while line is read from /etc/mdev.conf" */
 508         } while (ENABLE_FEATURE_MDEV_CONF);
 509
 510         if (ENABLE_FEATURE_MDEV_CONF)
 511                 config_close(parser);
 512         free(subsystem_slash_devname);
 513 }
 514
 515 /* File callback for /sys/ traversal */
 516 static int FAST_FUNC fileAction(const char *fileName,
 517                 struct stat *statbuf UNUSED_PARAM,
 518                 void *userData,
 519                 int depth UNUSED_PARAM)
 520 {
 521         size_t len = strlen(fileName) - 4; /* can't underflow */
 522         char *scratch = userData;
 523
 524         /* len check is for paranoid reasons */
 525         if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
 526                 return FALSE;
 527
 528         strcpy(scratch, fileName);
 529         scratch[len] = '\0';
 530         make_device(scratch, /*delete:*/ 0);
 531
 532         return TRUE;
 533 }
 534
 535 /* Directory callback for /sys/ traversal */
 536 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
 537                 struct stat *statbuf UNUSED_PARAM,
 538                 void *userData UNUSED_PARAM,
 539                 int depth)
 540 {
 541         /* Extract device subsystem -- the name of the directory
 542          * under /sys/class/ */
 543         if (1 == depth) {
 544                 free(G.subsystem);
 545                 G.subsystem = strrchr(fileName, '/');
 546                 if (G.subsystem)
 547                         G.subsystem = xstrdup(G.subsystem + 1);
 548         }
 549
 550         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 551 }
 552
 553 /* For the full gory details, see linux/Documentation/firmware_class/README
 554  *
 555  * Firmware loading works like this:
 556  * - kernel sets FIRMWARE env var
 557  * - userspace checks /lib/firmware/$FIRMWARE
 558  * - userspace waits for /sys/$DEVPATH/loading to appear
 559  * - userspace writes "1" to /sys/$DEVPATH/loading
 560  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 561  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 562  * - kernel loads firmware into device
 563  */
 564 static void load_firmware(const char *firmware, const char *sysfs_path)
 565 {
 566         int cnt;
 567         int firmware_fd, loading_fd, data_fd;
 568
 569         /* check for /lib/firmware/$FIRMWARE */
 570         xchdir("/lib/firmware");
 571         firmware_fd = xopen(firmware, O_RDONLY);
 572
 573         /* in case we goto out ... */
 574         data_fd = -1;
 575
 576         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 577         xchdir(sysfs_path);
 578         for (cnt = 0; cnt < 30; ++cnt) {
 579                 loading_fd = open("loading", O_WRONLY);
 580                 if (loading_fd != -1)
 581                         goto loading;
 582                 sleep(1);
 583         }
 584         goto out;
 585
 586  loading:
 587         /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
 588         if (full_write(loading_fd, "1", 1) != 1)
 589                 goto out;
 590
 591         /* load firmware into /sys/$DEVPATH/data */
 592         data_fd = open("data", O_WRONLY);
 593         if (data_fd == -1)
 594                 goto out;
 595         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 596
 597         /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */
 598         if (cnt > 0)
 599                 full_write(loading_fd, "0", 1);
 600         else
 601                 full_write(loading_fd, "-1", 2);
 602
 603  out:
 604         if (ENABLE_FEATURE_CLEAN_UP) {
 605                 close(firmware_fd);
 606                 close(loading_fd);
 607                 close(data_fd);
 608         }
 609 }
 610
 611 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 612 int mdev_main(int argc UNUSED_PARAM, char **argv)
 613 {
 614         RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
 615
 616         /* We can be called as hotplug helper */
 617         /* Kernel cannot provide suitable stdio fds for us, do it ourself */
 618         bb_sanitize_stdio();
 619
 620         /* Force the configuration file settings exactly */
 621         umask(0);
 622
 623         xchdir("/dev");
 624
 625         if (argv[1] && strcmp(argv[1], "-s") == 0) {
 626                 /* Scan:
 627                  * mdev -s
 628                  */
 629                 struct stat st;
 630
 631                 xstat("/", &st);
 632                 G.root_major = major(st.st_dev);
 633                 G.root_minor = minor(st.st_dev);
 634
 635                 /* ACTION_FOLLOWLINKS is needed since in newer kernels
 636                  * /sys/block/loop* (for example) are symlinks to dirs,
 637                  * not real directories.
 638                  * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
 639                  * but we can't enforce that on users)
 640                  */
 641                 if (access("/sys/class/block", F_OK) != 0) {
 642                         /* Scan obsolete /sys/block only if /sys/class/block
 643                          * doesn't exist. Otherwise we'll have dupes.
 644                          * Also, do not complain if it doesn't exist.
 645                          * Some people configure kernel to have no blockdevs.
 646                          */
 647                         recursive_action("/sys/block",
 648                                 ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
 649                                 fileAction, dirAction, temp, 0);
 650                 }
 651                 recursive_action("/sys/class",
 652                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 653                         fileAction, dirAction, temp, 0);
 654         } else {
 655                 char *fw;
 656                 char *seq;
 657                 char *action;
 658                 char *env_path;
 659                 static const char keywords[] ALIGN1 = "remove\0add\0";
 660                 enum { OP_remove = 0, OP_add };
 661                 smalluint op;
 662
 663                 /* Hotplug:
 664                  * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
 665                  * ACTION can be "add" or "remove"
 666                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 667                  */
 668                 action = getenv("ACTION");
 669                 env_path = getenv("DEVPATH");
 670                 G.subsystem = getenv("SUBSYSTEM");
 671                 if (!action || !env_path /*|| !G.subsystem*/)
 672                         bb_show_usage();
 673                 fw = getenv("FIRMWARE");
 674                 op = index_in_strings(keywords, action);
 675                 /* If it exists, does /dev/mdev.seq match $SEQNUM?
 676                  * If it does not match, earlier mdev is running
 677                  * in parallel, and we need to wait */
 678                 seq = getenv("SEQNUM");
 679                 if (seq) {
 680                         int timeout = 2000 / 32; /* 2000 msec */
 681                         do {
 682                                 int seqlen;
 683                                 char seqbuf[sizeof(int)*3 + 2];
 684
 685                                 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
 686                                 if (seqlen < 0) {
 687                                         seq = NULL;
 688                                         break;
 689                                 }
 690                                 seqbuf[seqlen] = '\0';
 691                                 if (seqbuf[0] == '\n' /* seed file? */
 692                                  || strcmp(seq, seqbuf) == 0 /* correct idx? */
 693                                 ) {
 694                                         break;
 695                                 }
 696                                 usleep(32*1000);
 697                         } while (--timeout);
 698                 }
 699
 700                 snprintf(temp, PATH_MAX, "/sys%s", env_path);
 701                 if (op == OP_remove) {
 702                         /* Ignoring "remove firmware". It was reported
 703                          * to happen and to cause erroneous deletion
 704                          * of device nodes. */
 705                         if (!fw)
 706                                 make_device(temp, /*delete:*/ 1);
 707                 }
 708                 else if (op == OP_add) {
 709                         make_device(temp, /*delete:*/ 0);
 710                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
 711                                 if (fw)
 712                                         load_firmware(fw, temp);
 713                         }
 714                 }
 715
 716                 if (seq) {
 717                         xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
 718                 }
 719         }
 720
 721         if (ENABLE_FEATURE_CLEAN_UP)
 722                 RELEASE_CONFIG_BUFFER(temp);
 723
 724         return EXIT_SUCCESS;
 725 }