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.
13 /* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
14 * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
15 * contains "4:0\n". Directory name is taken as device name, path component
16 * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty".
17 * Then mdev creates the /dev/device_name node.
18 * If /sys/class/.../dev file does not exist, mdev still may act
19 * on this device: see "@|$|*command args..." parameter in config file.
21 * mdev w/o parameters is called as hotplug helper. It takes device
22 * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts
23 * maj,min from "/sys/$DEVPATH/dev" and also examines
24 * $ACTION ("add"/"delete") and $FIRMWARE.
26 * If action is "add", mdev creates /dev/device_name similarly to mdev -s.
27 * (todo: explain "delete" and $FIRMWARE)
29 * If /etc/mdev.conf exists, it may modify /dev/device_name's properties.
30 * /etc/mdev.conf file format:
32 * [-][subsystem/]device user:grp mode [>|=path] [@|$|*command args...]
33 * [-]@maj,min[-min2] user:grp mode [>|=path] [@|$|*command args...]
34 * [-]$envvar=val user:grp mode [>|=path] [@|$|*command args...]
36 * Leading minus in 1st field means "don't stop on this line", otherwise
37 * search is stopped after the matching line is encountered.
39 * The device name or "subsystem/device" combo is matched against 1st field
40 * (which is a regex), or maj,min is matched against 1st field,
41 * or specified environment variable (as regex) is matched against 1st field.
43 * $envvar=val format is useful for loading modules for hot-plugged devices
44 * which do not have driver loaded yet. In this case /sys/class/.../dev
45 * does not exist, but $MODALIAS is set to needed module's name
46 * (actually, an alias to it) by kernel. This rule instructs mdev
47 * to load the module and exit:
48 * $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS"
49 * The kernel will generate another hotplug event when /sys/class/.../dev
52 * When line matches, the device node is created, chmod'ed and chown'ed,
53 * moved to path, and if >path, a symlink to moved node is created,
54 * all this if /sys/class/.../dev exists.
56 * =loop/ - moves to /dev/loop
57 * >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink
59 * Then "command args..." is executed (via sh -c 'command args...').
60 * @:execute on creation, $:on deletion, *:on both.
61 * This happens regardless of /sys/class/.../dev existence.
65 int root_major
, root_minor
;
68 #define G (*(struct globals*)&bb_common_bufsiz1)
70 /* Prevent infinite loops in /sys symlinks */
71 #define MAX_SYSFS_DEPTH 3
73 /* We use additional 64+ bytes in make_device() */
74 #define SCRATCH_SIZE 80
76 /* Builds an alias path.
77 * This function potentionally reallocates the alias parameter.
78 * Only used for ENABLE_FEATURE_MDEV_RENAME
80 static char *build_alias(char *alias
, const char *device_name
)
84 /* ">bar/": rename to bar/device_name */
85 /* ">bar[/]baz": rename to bar[/]baz */
86 dest
= strrchr(alias
, '/');
87 if (dest
) { /* ">bar/[baz]" ? */
88 *dest
= '\0'; /* mkdir bar */
89 bb_make_directory(alias
, 0755, FILEUTILS_RECUR
);
91 if (dest
[1] == '\0') { /* ">bar/" => ">bar/device_name" */
93 alias
= concat_path_file(alias
, device_name
);
101 /* mknod in /dev based on a path like "/sys/block/hda/hda1"
102 * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
103 * after NUL, but we promise to not mangle (IOW: to restore if needed)
105 * NB2: "mdev -s" may call us many times, do not leak memory/fds!
107 static void make_device(char *path
, int delete)
109 char *device_name
, *subsystem_slash_devname
;
110 int major
, minor
, type
, len
;
114 /* Try to read major/minor string. Note that the kernel puts \n after
115 * the data, so we don't need to worry about null terminating the string
116 * because sscanf() will stop at the first nondigit, which \n is.
117 * We also depend on path having writeable space after it.
121 char *dev_maj_min
= path
+ strlen(path
);
123 strcpy(dev_maj_min
, "/dev");
124 len
= open_read_close(path
, dev_maj_min
+ 1, 64);
127 if (!ENABLE_FEATURE_MDEV_EXEC
)
129 /* no "dev" file, but we can still run scripts
130 * based on device name */
131 } else if (sscanf(++dev_maj_min
, "%u:%u", &major
, &minor
) != 2) {
135 /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
137 /* Determine device name, type, major and minor */
138 device_name
= (char*) bb_basename(path
);
139 /* http://kernel.org/doc/pending/hotplug.txt says that only
140 * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
141 * But since 2.6.25 block devices are also in /sys/class/block.
142 * We use strstr("/block/") to forestall future surprises. */
144 if (strstr(path
, "/block/") || (G
.subsystem
&& strncmp(G
.subsystem
, "block", 5) == 0))
147 /* Make path point to "subsystem/device_name" */
148 subsystem_slash_devname
= NULL
;
149 /* Check for coldplug invocations first */
150 if (strncmp(path
, "/sys/block/", 11) == 0) /* legacy case */
151 path
+= sizeof("/sys/") - 1;
152 else if (strncmp(path
, "/sys/class/", 11) == 0)
153 path
+= sizeof("/sys/class/") - 1;
155 /* Example of a hotplug invocation:
157 * DEVPATH="/sys" + "/devices/virtual/mtd/mtd3/mtdblock3"
158 * ("/sys" is added by mdev_main)
159 * - path does not contain subsystem
161 subsystem_slash_devname
= concat_path_file(G
.subsystem
, device_name
);
162 path
= subsystem_slash_devname
;
165 /* If we have config file, look up user settings */
166 if (ENABLE_FEATURE_MDEV_CONF
)
167 parser
= config_open2("/etc/mdev.conf", fopen_for_read
);
171 struct bb_uidgid_t ugid
;
173 char *command
= NULL
;
175 char aliaslink
= aliaslink
; /* for compiler */
177 /* Defaults in case we won't match any line */
178 ugid
.uid
= ugid
.gid
= 0;
182 if (ENABLE_FEATURE_MDEV_CONF
183 && config_read(parser
, tokens
, 4, 3, "# \t", PARSE_NORMAL
)
187 regmatch_t off
[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP
];
190 keep_matching
= ('-' == val
[0]);
191 val
+= keep_matching
; /* swallow leading dash */
193 /* Match against either "subsystem/device_name"
194 * or "device_name" alone */
195 str_to_match
= strchr(val
, '/') ? path
: device_name
;
197 /* Fields: regex uid:gid mode [alias] [cmd] */
200 /* @major,minor[-minor2] */
201 /* (useful when name is ambiguous:
202 * "/sys/class/usb/lp0" and
203 * "/sys/class/printer/lp0") */
204 int cmaj
, cmin0
, cmin1
, sc
;
206 continue; /* no dev, no match */
207 sc
= sscanf(val
, "@%u,%u-%u", &cmaj
, &cmin0
, &cmin1
);
210 || (sc
== 2 && minor
!= cmin0
)
211 || (sc
== 3 && (minor
< cmin0
|| minor
> cmin1
))
213 continue; /* this line doesn't match */
218 /* regex to match an environment variable */
219 char *eq
= strchr(++val
, '=');
223 str_to_match
= getenv(val
);
226 str_to_match
-= strlen(val
) + 1;
229 /* else: regex to match [subsystem/]device_name */
235 xregcomp(&match
, val
, REG_EXTENDED
);
236 result
= regexec(&match
, str_to_match
, ARRAY_SIZE(off
), off
, 0);
238 //bb_error_msg("matches:");
239 //for (int i = 0; i < ARRAY_SIZE(off); i++) {
240 // if (off[i].rm_so < 0) continue;
241 // bb_error_msg("match %d: '%.*s'\n", i,
242 // (int)(off[i].rm_eo - off[i].rm_so),
243 // device_name + off[i].rm_so);
246 /* If no match, skip rest of line */
247 /* (regexec returns whole pattern as "range" 0) */
250 || ((int)off
[0].rm_eo
!= (int)strlen(str_to_match
))
252 continue; /* this line doesn't match */
256 /* This line matches. Stop parsing after parsing
257 * the rest the line unless keep_matching == 1 */
259 /* 2nd field: uid:gid - device ownership */
260 if (get_uidgid(&ugid
, tokens
[1], 1) == 0)
261 bb_error_msg("unknown user/group %s on line %d", tokens
[1], parser
->lineno
);
263 /* 3rd field: mode - device permissions */
264 bb_parse_mode(tokens
[2], &mode
);
267 /* 4th field (opt): ">|=alias" or "!" to not create the node */
269 if (ENABLE_FEATURE_MDEV_RENAME
&& val
) {
273 s
= strchrnul(val
, ' ');
274 st
= strchrnul(val
, '\t');
277 st
= (s
[0] && s
[1]) ? s
+1 : NULL
;
280 if (aliaslink
== '!' && s
== a
+1) {
282 /* "!": suppress node creation/deletion */
285 else if (aliaslink
== '>' || aliaslink
== '=') {
288 if (ENABLE_FEATURE_MDEV_RENAME_REGEXP
) {
292 /* substitute %1..9 with off[1..9], if any */
299 p
= alias
= xzalloc(strlen(a
) + n
* strlen(str_to_match
));
305 if (i
<= 9 && off
[i
].rm_so
>= 0) {
306 n
= off
[i
].rm_eo
- off
[i
].rm_so
;
307 strncpy(p
, str_to_match
+ off
[i
].rm_so
, n
);
316 alias
= xstrdup(a
+ 1);
321 if (ENABLE_FEATURE_MDEV_EXEC
&& val
) {
322 const char *s
= "$@*";
323 const char *s2
= strchr(s
, val
[0]);
326 bb_error_msg("bad line %u", parser
->lineno
);
327 if (ENABLE_FEATURE_MDEV_RENAME
)
332 /* Are we running this command now?
333 * Run $cmd on delete, @cmd on create, *cmd on both
335 if (s2
- s
!= delete) {
336 /* We are here if: '*',
337 * or: '@' and delete = 0,
338 * or: '$' and delete = 1
340 command
= xstrdup(val
+ 1);
345 /* End of field parsing */
347 /* "Execute" the line we found */
349 const char *node_name
;
351 node_name
= device_name
;
352 if (ENABLE_FEATURE_MDEV_RENAME
&& alias
)
353 node_name
= alias
= build_alias(alias
, device_name
);
355 if (!delete && major
>= 0) {
356 if (mknod(node_name
, mode
| type
, makedev(major
, minor
)) && errno
!= EEXIST
)
357 bb_perror_msg("can't create '%s'", node_name
);
358 if (major
== G
.root_major
&& minor
== G
.root_minor
)
359 symlink(node_name
, "root");
360 if (ENABLE_FEATURE_MDEV_CONF
) {
361 chmod(node_name
, mode
);
362 chown(node_name
, ugid
.uid
, ugid
.gid
);
364 if (ENABLE_FEATURE_MDEV_RENAME
&& alias
) {
365 if (aliaslink
== '>')
366 symlink(node_name
, device_name
);
370 if (ENABLE_FEATURE_MDEV_EXEC
&& command
) {
371 /* setenv will leak memory, use putenv/unsetenv/free */
372 char *s
= xasprintf("%s=%s", "MDEV", node_name
);
373 char *s1
= xasprintf("%s=%s", "SUBSYSTEM", G
.subsystem
);
376 if (system(command
) == -1)
377 bb_perror_msg("can't run '%s'", command
);
378 bb_unsetenv_and_free(s1
);
379 bb_unsetenv_and_free(s
);
383 if (delete && major
>= -1) {
384 if (ENABLE_FEATURE_MDEV_RENAME
&& alias
) {
385 if (aliaslink
== '>')
391 if (ENABLE_FEATURE_MDEV_RENAME
)
395 /* We found matching line.
396 * Stop unless it was prefixed with '-' */
397 if (ENABLE_FEATURE_MDEV_CONF
&& !keep_matching
)
400 /* end of "while line is read from /etc/mdev.conf" */
401 } while (ENABLE_FEATURE_MDEV_CONF
);
403 if (ENABLE_FEATURE_MDEV_CONF
)
404 config_close(parser
);
405 free(subsystem_slash_devname
);
408 /* File callback for /sys/ traversal */
409 static int FAST_FUNC
fileAction(const char *fileName
,
410 struct stat
*statbuf UNUSED_PARAM
,
412 int depth UNUSED_PARAM
)
414 size_t len
= strlen(fileName
) - 4; /* can't underflow */
415 char *scratch
= userData
;
417 /* len check is for paranoid reasons */
418 if (strcmp(fileName
+ len
, "/dev") != 0 || len
>= PATH_MAX
)
421 strcpy(scratch
, fileName
);
423 make_device(scratch
, /*delete:*/ 0);
428 /* Directory callback for /sys/ traversal */
429 static int FAST_FUNC
dirAction(const char *fileName UNUSED_PARAM
,
430 struct stat
*statbuf UNUSED_PARAM
,
431 void *userData UNUSED_PARAM
,
434 /* Extract device subsystem -- the name of the directory
435 * under /sys/class/ */
438 G
.subsystem
= strrchr(fileName
, '/');
440 G
.subsystem
= xstrdup(G
.subsystem
+ 1);
443 return (depth
>= MAX_SYSFS_DEPTH
? SKIP
: TRUE
);
446 /* For the full gory details, see linux/Documentation/firmware_class/README
448 * Firmware loading works like this:
449 * - kernel sets FIRMWARE env var
450 * - userspace checks /lib/firmware/$FIRMWARE
451 * - userspace waits for /sys/$DEVPATH/loading to appear
452 * - userspace writes "1" to /sys/$DEVPATH/loading
453 * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
454 * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
455 * - kernel loads firmware into device
457 static void load_firmware(const char *firmware
, const char *sysfs_path
)
460 int firmware_fd
, loading_fd
, data_fd
;
462 /* check for /lib/firmware/$FIRMWARE */
463 xchdir("/lib/firmware");
464 firmware_fd
= xopen(firmware
, O_RDONLY
);
466 /* in case we goto out ... */
469 /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
471 for (cnt
= 0; cnt
< 30; ++cnt
) {
472 loading_fd
= open("loading", O_WRONLY
);
473 if (loading_fd
!= -1)
480 /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
481 if (full_write(loading_fd
, "1", 1) != 1)
484 /* load firmware into /sys/$DEVPATH/data */
485 data_fd
= open("data", O_WRONLY
);
488 cnt
= bb_copyfd_eof(firmware_fd
, data_fd
);
490 /* tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading" */
492 full_write(loading_fd
, "0", 1);
494 full_write(loading_fd
, "-1", 2);
497 if (ENABLE_FEATURE_CLEAN_UP
) {
504 int mdev_main(int argc
, char **argv
) MAIN_EXTERNALLY_VISIBLE
;
505 int mdev_main(int argc UNUSED_PARAM
, char **argv
)
507 RESERVE_CONFIG_BUFFER(temp
, PATH_MAX
+ SCRATCH_SIZE
);
509 /* We can be called as hotplug helper */
510 /* Kernel cannot provide suitable stdio fds for us, do it ourself */
513 /* Force the configuration file settings exactly */
518 if (argv
[1] && strcmp(argv
[1], "-s") == 0) {
525 G
.root_major
= major(st
.st_dev
);
526 G
.root_minor
= minor(st
.st_dev
);
528 /* ACTION_FOLLOWLINKS is needed since in newer kernels
529 * /sys/block/loop* (for example) are symlinks to dirs,
530 * not real directories.
531 * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
532 * but we can't enforce that on users)
534 if (access("/sys/class/block", F_OK
) != 0) {
535 /* Scan obsolete /sys/block only if /sys/class/block
536 * doesn't exist. Otherwise we'll have dupes.
537 * Also, do not complain if it doesn't exist.
538 * Some people configure kernel to have no blockdevs.
540 recursive_action("/sys/block",
541 ACTION_RECURSE
| ACTION_FOLLOWLINKS
| ACTION_QUIET
,
542 fileAction
, dirAction
, temp
, 0);
544 recursive_action("/sys/class",
545 ACTION_RECURSE
| ACTION_FOLLOWLINKS
,
546 fileAction
, dirAction
, temp
, 0);
552 static const char keywords
[] ALIGN1
= "remove\0add\0";
553 enum { OP_remove
= 0, OP_add
};
557 * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
558 * ACTION can be "add" or "remove"
559 * DEVPATH is like "/block/sda" or "/class/input/mice"
561 action
= getenv("ACTION");
562 env_path
= getenv("DEVPATH");
563 G
.subsystem
= getenv("SUBSYSTEM");
564 if (!action
|| !env_path
/*|| !G.subsystem*/)
566 fw
= getenv("FIRMWARE");
567 op
= index_in_strings(keywords
, action
);
568 /* If it exists, does /dev/mdev.seq match $SEQNUM?
569 * If it does not match, earlier mdev is running
570 * in parallel, and we need to wait */
571 seq
= getenv("SEQNUM");
573 int timeout
= 2000 / 32; /* 2000 msec */
576 char seqbuf
[sizeof(int)*3 + 2];
578 seqlen
= open_read_close("mdev.seq", seqbuf
, sizeof(seqbuf
-1));
583 seqbuf
[seqlen
] = '\0';
584 if (seqbuf
[0] == '\n' /* seed file? */
585 || strcmp(seq
, seqbuf
) == 0 /* correct idx? */
593 snprintf(temp
, PATH_MAX
, "/sys%s", env_path
);
594 if (op
== OP_remove
) {
595 /* Ignoring "remove firmware". It was reported
596 * to happen and to cause erroneous deletion
597 * of device nodes. */
599 make_device(temp
, /*delete:*/ 1);
601 else if (op
== OP_add
) {
602 make_device(temp
, /*delete:*/ 0);
603 if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE
) {
605 load_firmware(fw
, temp
);
610 xopen_xwrite_close("mdev.seq", utoa(xatou(seq
) + 1));
614 if (ENABLE_FEATURE_CLEAN_UP
)
615 RELEASE_CONFIG_BUFFER(temp
);