1 /* vi: set sw=4 ts=4: */
3 * mdev - Mini udev for busybox
5 * Copyright 2005 Rob Landley <rob@landley.net>
6 * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
8 * Licensed under GPLv2, see file LICENSE in this source tree.
11 //usage:#define mdev_trivial_usage
13 //usage:#define mdev_full_usage "\n\n"
14 //usage: " -s Scan /sys and populate /dev during system boot\n"
16 //usage: "It can be run by kernel as a hotplug helper. To activate it:\n"
17 //usage: " echo /sbin/mdev > /proc/sys/kernel/hotplug\n"
18 //usage: IF_FEATURE_MDEV_CONF(
19 //usage: "It uses /etc/mdev.conf with lines\n"
20 //usage: "[-]DEVNAME UID:GID PERM"
21 //usage: IF_FEATURE_MDEV_RENAME(" [>|=PATH]")
22 //usage: IF_FEATURE_MDEV_EXEC(" [@|$|*PROG]")
25 //usage:#define mdev_notes_usage ""
26 //usage: IF_FEATURE_MDEV_CONFIG(
27 //usage: "The mdev config file contains lines that look like:\n"
28 //usage: " hd[a-z][0-9]* 0:3 660\n\n"
29 //usage: "That's device name (with regex match), uid:gid, and permissions.\n\n"
30 //usage: IF_FEATURE_MDEV_EXEC(
31 //usage: "Optionally, that can be followed (on the same line) by a special character\n"
32 //usage: "and a command line to run after creating/before deleting the corresponding\n"
33 //usage: "device(s). The environment variable $MDEV indicates the active device node\n"
34 //usage: "(which is useful if it's a regex match). For example:\n\n"
35 //usage: " hdc root:cdrom 660 *ln -s $MDEV cdrom\n\n"
36 //usage: "The special characters are @ (run after creating), $ (run before deleting),\n"
37 //usage: "and * (run both after creating and before deleting). The commands run in\n"
38 //usage: "the /dev directory, and use system() which calls /bin/sh.\n\n"
40 //usage: "Config file parsing stops on the first matching line. If no config\n"
41 //usage: "entry is matched, devices are created with default 0:0 660. (Make\n"
42 //usage: "the last line match .* to override this.)\n\n"
48 /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
49 * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
50 * contains "4:0\n". Directory name is taken as device name, path component
51 * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty".
52 * Then mdev creates the /dev/device_name node.
53 * If /sys/class/.../dev file does not exist, mdev still may act
54 * on this device: see "@|$|*command args..." parameter in config file.
56 * mdev w/o parameters is called as hotplug helper. It takes device
57 * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts
58 * maj,min from "/sys/$DEVPATH/dev" and also examines
59 * $ACTION ("add"/"delete") and $FIRMWARE.
61 * If action is "add", mdev creates /dev/device_name similarly to mdev -s.
62 * (todo: explain "delete" and $FIRMWARE)
64 * If /etc/mdev.conf exists, it may modify /dev/device_name's properties.
65 * /etc/mdev.conf file format:
67 * [-][subsystem/]device user:grp mode [>|=path] [@|$|*command args...]
68 * [-]@maj,min[-min2] user:grp mode [>|=path] [@|$|*command args...]
69 * [-]$envvar=val user:grp mode [>|=path] [@|$|*command args...]
71 * Leading minus in 1st field means "don't stop on this line", otherwise
72 * search is stopped after the matching line is encountered.
74 * The device name or "subsystem/device" combo is matched against 1st field
75 * (which is a regex), or maj,min is matched against 1st field,
76 * or specified environment variable (as regex) is matched against 1st field.
78 * $envvar=val format is useful for loading modules for hot-plugged devices
79 * which do not have driver loaded yet. In this case /sys/class/.../dev
80 * does not exist, but $MODALIAS is set to needed module's name
81 * (actually, an alias to it) by kernel. This rule instructs mdev
82 * to load the module and exit:
83 * $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS"
84 * The kernel will generate another hotplug event when /sys/class/.../dev
87 * When line matches, the device node is created, chmod'ed and chown'ed,
88 * moved to path, and if >path, a symlink to moved node is created,
89 * all this if /sys/class/.../dev exists.
91 * =loop/ - moves to /dev/loop
92 * >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink
94 * Then "command args..." is executed (via sh -c 'command args...').
95 * @:execute on creation, $:on deletion, *:on both.
96 * This happens regardless of /sys/class/.../dev existence.
100 int root_major, root_minor;
103 #define G (*(struct globals*)&bb_common_bufsiz1)
105 /* Prevent infinite loops in /sys symlinks */
106 #define MAX_SYSFS_DEPTH 3
108 /* We use additional 64+ bytes in make_device() */
109 #define SCRATCH_SIZE 80
111 /* Builds an alias path.
112 * This function potentionally reallocates the alias parameter.
113 * Only used for ENABLE_FEATURE_MDEV_RENAME
115 static char *build_alias(char *alias, const char *device_name)
119 /* ">bar/": rename to bar/device_name */
120 /* ">bar[/]baz": rename to bar[/]baz */
121 dest = strrchr(alias, '/');
122 if (dest) { /* ">bar/[baz]" ? */
123 *dest = '\0'; /* mkdir bar */
124 bb_make_directory(alias, 0755, FILEUTILS_RECUR);
126 if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
128 alias = concat_path_file(alias, device_name);
136 /* mknod in /dev based on a path like "/sys/block/hda/hda1"
137 * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
138 * after NUL, but we promise to not mangle (IOW: to restore if needed)
140 * NB2: "mdev -s" may call us many times, do not leak memory/fds!
142 static void make_device(char *path, int delete)
144 char *device_name, *subsystem_slash_devname;
145 int major, minor, type, len;
149 /* Try to read major/minor string. Note that the kernel puts \n after
150 * the data, so we don't need to worry about null terminating the string
151 * because sscanf() will stop at the first nondigit, which \n is.
152 * We also depend on path having writeable space after it.
156 char *dev_maj_min = path + strlen(path);
158 strcpy(dev_maj_min, "/dev");
159 len = open_read_close(path, dev_maj_min + 1, 64);
162 if (!ENABLE_FEATURE_MDEV_EXEC)
164 /* no "dev" file, but we can still run scripts
165 * based on device name */
166 } else if (sscanf(++dev_maj_min, "%u:%u", &major, &minor) != 2) {
170 /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
172 /* Determine device name, type, major and minor */
173 device_name = (char*) bb_basename(path);
174 /* http://kernel.org/doc/pending/hotplug.txt says that only
175 * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
176 * But since 2.6.25 block devices are also in /sys/class/block.
177 * We use strstr("/block/") to forestall future surprises. */
179 if (strstr(path, "/block/") || (G.subsystem && strncmp(G.subsystem, "block", 5) == 0))
182 /* Make path point to "subsystem/device_name" */
183 subsystem_slash_devname = NULL;
184 /* Check for coldplug invocations first */
185 if (strncmp(path, "/sys/block/", 11) == 0) /* legacy case */
186 path += sizeof("/sys/") - 1;
187 else if (strncmp(path, "/sys/class/", 11) == 0)
188 path += sizeof("/sys/class/") - 1;
190 /* Example of a hotplug invocation:
192 * DEVPATH="/sys" + "/devices/virtual/mtd/mtd3/mtdblock3"
193 * ("/sys" is added by mdev_main)
194 * - path does not contain subsystem
196 subsystem_slash_devname = concat_path_file(G.subsystem, device_name);
197 path = subsystem_slash_devname;
200 /* If we have config file, look up user settings */
201 if (ENABLE_FEATURE_MDEV_CONF)
202 parser = config_open2("/etc/mdev.conf", fopen_for_read);
206 struct bb_uidgid_t ugid;
208 char *command = NULL;
210 char aliaslink = aliaslink; /* for compiler */
212 /* Defaults in case we won't match any line */
213 ugid.uid = ugid.gid = 0;
217 if (ENABLE_FEATURE_MDEV_CONF
218 && config_read(parser, tokens, 4, 3, "# \t", PARSE_NORMAL)
222 regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
225 keep_matching = ('-' == val[0]);
226 val += keep_matching; /* swallow leading dash */
228 /* Match against either "subsystem/device_name"
229 * or "device_name" alone */
230 str_to_match = strchr(val, '/') ? path : device_name;
232 /* Fields: regex uid:gid mode [alias] [cmd] */
235 /* @major,minor[-minor2] */
236 /* (useful when name is ambiguous:
237 * "/sys/class/usb/lp0" and
238 * "/sys/class/printer/lp0") */
239 int cmaj, cmin0, cmin1, sc;
241 continue; /* no dev, no match */
242 sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
245 || (sc == 2 && minor != cmin0)
246 || (sc == 3 && (minor < cmin0 || minor > cmin1))
248 continue; /* this line doesn't match */
253 /* regex to match an environment variable */
254 char *eq = strchr(++val, '=');
258 str_to_match = getenv(val);
261 str_to_match -= strlen(val) + 1;
264 /* else: regex to match [subsystem/]device_name */
270 xregcomp(&match, val, REG_EXTENDED);
271 result = regexec(&match, str_to_match, ARRAY_SIZE(off), off, 0);
273 //bb_error_msg("matches:");
274 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
275 // if (off[i].rm_so < 0) continue;
276 // bb_error_msg("match %d: '%.*s'\n", i,
277 // (int)(off[i].rm_eo - off[i].rm_so),
278 // device_name + off[i].rm_so);
281 /* If no match, skip rest of line */
282 /* (regexec returns whole pattern as "range" 0) */
285 || ((int)off[0].rm_eo != (int)strlen(str_to_match))
287 continue; /* this line doesn't match */
291 /* This line matches. Stop parsing after parsing
292 * the rest the line unless keep_matching == 1 */
294 /* 2nd field: uid:gid - device ownership */
295 if (get_uidgid(&ugid, tokens[1], /*allow_numeric:*/ 1) == 0)
296 bb_error_msg("unknown user/group %s on line %d", tokens[1], parser->lineno);
298 /* 3rd field: mode - device permissions */
299 bb_parse_mode(tokens[2], &mode);
302 /* 4th field (opt): ">|=alias" or "!" to not create the node */
304 if (ENABLE_FEATURE_MDEV_RENAME && val) {
308 s = strchrnul(val, ' ');
309 st = strchrnul(val, '\t');
312 st = (s[0] && s[1]) ? s+1 : NULL;
315 if (aliaslink == '!' && s == a+1) {
317 /* "!": suppress node creation/deletion */
320 else if (aliaslink == '>' || aliaslink == '=') {
323 if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
327 /* substitute %1..9 with off[1..9], if any */
334 p = alias = xzalloc(strlen(a) + n * strlen(str_to_match));
340 if (i <= 9 && off[i].rm_so >= 0) {
341 n = off[i].rm_eo - off[i].rm_so;
342 strncpy(p, str_to_match + off[i].rm_so, n);
351 alias = xstrdup(a + 1);
356 if (ENABLE_FEATURE_MDEV_EXEC && val) {
357 const char *s = "$@*";
358 const char *s2 = strchr(s, val[0]);
361 bb_error_msg("bad line %u", parser->lineno);
362 if (ENABLE_FEATURE_MDEV_RENAME)
367 /* Are we running this command now?
368 * Run $cmd on delete, @cmd on create, *cmd on both
370 if (s2 - s != delete) {
371 /* We are here if: '*',
372 * or: '@' and delete = 0,
373 * or: '$' and delete = 1
375 command = xstrdup(val + 1);
380 /* End of field parsing */
382 /* "Execute" the line we found */
384 const char *node_name;
386 node_name = device_name;
387 if (ENABLE_FEATURE_MDEV_RENAME && alias)
388 node_name = alias = build_alias(alias, device_name);
390 if (!delete && major >= 0) {
391 if (mknod(node_name, mode | type, makedev(major, minor)) && errno != EEXIST)
392 bb_perror_msg("can't create '%s'", node_name);
393 if (major == G.root_major && minor == G.root_minor)
394 symlink(node_name, "root");
395 if (ENABLE_FEATURE_MDEV_CONF) {
396 chmod(node_name, mode);
397 chown(node_name, ugid.uid, ugid.gid);
399 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
400 if (aliaslink == '>')
401 symlink(node_name, device_name);
405 if (ENABLE_FEATURE_MDEV_EXEC && command) {
406 /* setenv will leak memory, use putenv/unsetenv/free */
407 char *s = xasprintf("%s=%s", "MDEV", node_name);
408 char *s1 = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
411 if (system(command) == -1)
412 bb_perror_msg("can't run '%s'", command);
413 bb_unsetenv_and_free(s1);
414 bb_unsetenv_and_free(s);
418 if (delete && major >= -1) {
419 if (ENABLE_FEATURE_MDEV_RENAME && alias) {
420 if (aliaslink == '>')
426 if (ENABLE_FEATURE_MDEV_RENAME)
430 /* We found matching line.
431 * Stop unless it was prefixed with '-' */
432 if (ENABLE_FEATURE_MDEV_CONF && !keep_matching)
435 /* end of "while line is read from /etc/mdev.conf" */
436 } while (ENABLE_FEATURE_MDEV_CONF);
438 if (ENABLE_FEATURE_MDEV_CONF)
439 config_close(parser);
440 free(subsystem_slash_devname);
443 /* File callback for /sys/ traversal */
444 static int FAST_FUNC fileAction(const char *fileName,
445 struct stat *statbuf UNUSED_PARAM,
447 int depth UNUSED_PARAM)
449 size_t len = strlen(fileName) - 4; /* can't underflow */
450 char *scratch = userData;
452 /* len check is for paranoid reasons */
453 if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
456 strcpy(scratch, fileName);
458 make_device(scratch, /*delete:*/ 0);
463 /* Directory callback for /sys/ traversal */
464 static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
465 struct stat *statbuf UNUSED_PARAM,
466 void *userData UNUSED_PARAM,
469 /* Extract device subsystem -- the name of the directory
470 * under /sys/class/ */
473 G.subsystem = strrchr(fileName, '/');
475 G.subsystem = xstrdup(G.subsystem + 1);
478 return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
481 /* For the full gory details, see linux/Documentation/firmware_class/README
483 * Firmware loading works like this:
484 * - kernel sets FIRMWARE env var
485 * - userspace checks /lib/firmware/$FIRMWARE
486 * - userspace waits for /sys/$DEVPATH/loading to appear
487 * - userspace writes "1" to /sys/$DEVPATH/loading
488 * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
489 * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
490 * - kernel loads firmware into device
492 static void load_firmware(const char *firmware, const char *sysfs_path)
495 int firmware_fd, loading_fd, data_fd;
497 /* check for /lib/firmware/$FIRMWARE */
498 xchdir("/lib/firmware");
499 firmware_fd = xopen(firmware, O_RDONLY);
501 /* in case we goto out ... */
504 /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
506 for (cnt = 0; cnt < 30; ++cnt) {
507 loading_fd = open("loading", O_WRONLY);
508 if (loading_fd != -1)
515 /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
516 if (full_write(loading_fd, "1", 1) != 1)
519 /* load firmware into /sys/$DEVPATH/data */
520 data_fd = open("data", O_WRONLY);
523 cnt = bb_copyfd_eof(firmware_fd, data_fd);
525 /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */
527 full_write(loading_fd, "0", 1);
529 full_write(loading_fd, "-1", 2);
532 if (ENABLE_FEATURE_CLEAN_UP) {
539 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
540 int mdev_main(int argc UNUSED_PARAM, char **argv)
542 RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
544 /* We can be called as hotplug helper */
545 /* Kernel cannot provide suitable stdio fds for us, do it ourself */
548 /* Force the configuration file settings exactly */
553 if (argv[1] && strcmp(argv[1], "-s") == 0) {
560 G.root_major = major(st.st_dev);
561 G.root_minor = minor(st.st_dev);
563 /* ACTION_FOLLOWLINKS is needed since in newer kernels
564 * /sys/block/loop* (for example) are symlinks to dirs,
565 * not real directories.
566 * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
567 * but we can't enforce that on users)
569 if (access("/sys/class/block", F_OK) != 0) {
570 /* Scan obsolete /sys/block only if /sys/class/block
571 * doesn't exist. Otherwise we'll have dupes.
572 * Also, do not complain if it doesn't exist.
573 * Some people configure kernel to have no blockdevs.
575 recursive_action("/sys/block",
576 ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
577 fileAction, dirAction, temp, 0);
579 recursive_action("/sys/class",
580 ACTION_RECURSE | ACTION_FOLLOWLINKS,
581 fileAction, dirAction, temp, 0);
587 static const char keywords[] ALIGN1 = "remove\0add\0";
588 enum { OP_remove = 0, OP_add };
592 * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
593 * ACTION can be "add" or "remove"
594 * DEVPATH is like "/block/sda" or "/class/input/mice"
596 action = getenv("ACTION");
597 env_path = getenv("DEVPATH");
598 G.subsystem = getenv("SUBSYSTEM");
599 if (!action || !env_path /*|| !G.subsystem*/)
601 fw = getenv("FIRMWARE");
602 op = index_in_strings(keywords, action);
603 /* If it exists, does /dev/mdev.seq match $SEQNUM?
604 * If it does not match, earlier mdev is running
605 * in parallel, and we need to wait */
606 seq = getenv("SEQNUM");
608 int timeout = 2000 / 32; /* 2000 msec */
611 char seqbuf[sizeof(int)*3 + 2];
613 seqlen = open_read_close("mdev.seq", seqbuf, sizeof(seqbuf-1));
618 seqbuf[seqlen] = '\0';
619 if (seqbuf[0] == '\n' /* seed file? */
620 || strcmp(seq, seqbuf) == 0 /* correct idx? */
628 snprintf(temp, PATH_MAX, "/sys%s", env_path);
629 if (op == OP_remove) {
630 /* Ignoring "remove firmware". It was reported
631 * to happen and to cause erroneous deletion
632 * of device nodes. */
634 make_device(temp, /*delete:*/ 1);
636 else if (op == OP_add) {
637 make_device(temp, /*delete:*/ 0);
638 if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
640 load_firmware(fw, temp);
645 xopen_xwrite_close("mdev.seq", utoa(xatou(seq) + 1));
649 if (ENABLE_FEATURE_CLEAN_UP)
650 RELEASE_CONFIG_BUFFER(temp);