source: branches/3.2/mindi-busybox/util-linux/mdev.c @ 3232

Last change on this file since 3232 was 3232, checked in by Bruno Cornec, 7 years ago
  • Update mindi-busybox to 1.21.1
File size: 31.0 KB
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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-$(CONFIG_MDEV) += mdev.o
72
73//usage:#define mdev_trivial_usage
74//usage:       "[-s]"
75//usage:#define mdev_full_usage "\n\n"
76//usage:       "mdev -s is to be run during boot to scan /sys and populate /dev.\n"
77//usage:       "\n"
78//usage:       "Bare mdev is a kernel hotplug helper. To activate it:\n"
79//usage:       "    echo /sbin/mdev >/proc/sys/kernel/hotplug\n"
80//usage:    IF_FEATURE_MDEV_CONF(
81//usage:       "\n"
82//usage:       "It uses /etc/mdev.conf with lines\n"
83//usage:       "    [-][ENV=regex;]...DEVNAME UID:GID PERM"
84//usage:            IF_FEATURE_MDEV_RENAME(" [>|=PATH]|[!]")
85//usage:            IF_FEATURE_MDEV_EXEC(" [@|$|*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 $SEQNUM variable. This prevents plug/unplug races.\n"
95//usage:       "To activate this feature, create empty /dev/mdev.seq at boot.\n"
96//usage:       "\n"
97//usage:       "If /dev/mdev.log file exists, debug log will be appended to it."
98
99#include "libbb.h"
100#include "xregex.h"
101
102/* "mdev -s" scans /sys/class/xxx, looking for directories which have dev
103 * file (it is of the form "M:m\n"). Example: /sys/class/tty/tty0/dev
104 * contains "4:0\n". Directory name is taken as device name, path component
105 * directly after /sys/class/ as subsystem. In this example, "tty0" and "tty".
106 * Then mdev creates the /dev/device_name node.
107 * If /sys/class/.../dev file does not exist, mdev still may act
108 * on this device: see "@|$|*command args..." parameter in config file.
109 *
110 * mdev w/o parameters is called as hotplug helper. It takes device
111 * and subsystem names from $DEVPATH and $SUBSYSTEM, extracts
112 * maj,min from "/sys/$DEVPATH/dev" and also examines
113 * $ACTION ("add"/"delete") and $FIRMWARE.
114 *
115 * If action is "add", mdev creates /dev/device_name similarly to mdev -s.
116 * (todo: explain "delete" and $FIRMWARE)
117 *
118 * If /etc/mdev.conf exists, it may modify /dev/device_name's properties.
119 *
120 * Leading minus in 1st field means "don't stop on this line", otherwise
121 * search is stopped after the matching line is encountered.
122 *
123 * $envvar=regex format is useful for loading modules for hot-plugged devices
124 * which do not have driver loaded yet. In this case /sys/class/.../dev
125 * does not exist, but $MODALIAS is set to needed module's name
126 * (actually, an alias to it) by kernel. This rule instructs mdev
127 * to load the module and exit:
128 *    $MODALIAS=.* 0:0 660 @modprobe "$MODALIAS"
129 * The kernel will generate another hotplug event when /sys/class/.../dev
130 * file appears.
131 *
132 * When line matches, the device node is created, chmod'ed and chown'ed,
133 * moved to path, and if >path, a symlink to moved node is created,
134 * all this if /sys/class/.../dev exists.
135 *    Examples:
136 *    =loop/      - moves to /dev/loop
137 *    >disk/sda%1 - moves to /dev/disk/sdaN, makes /dev/sdaN a symlink
138 *
139 * Then "command args..." is executed (via sh -c 'command args...').
140 * @:execute on creation, $:on deletion, *:on both.
141 * This happens regardless of /sys/class/.../dev existence.
142 */
143
144/* Kernel's hotplug environment constantly changes.
145 * Here are new cases I observed on 3.1.0:
146 *
147 * Case with $DEVNAME and $DEVICE, not just $DEVPATH:
148 * ACTION=add
149 * BUSNUM=001
150 * DEVICE=/proc/bus/usb/001/003
151 * DEVNAME=bus/usb/001/003
152 * DEVNUM=003
153 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5
154 * DEVTYPE=usb_device
155 * MAJOR=189
156 * MINOR=2
157 * PRODUCT=18d1/4e12/227
158 * SUBSYSTEM=usb
159 * TYPE=0/0/0
160 *
161 * Case with $DEVICE, but no $DEVNAME - apparenty, usb iface notification?
162 * "Please load me a module" thing?
163 * ACTION=add
164 * DEVICE=/proc/bus/usb/001/003
165 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0
166 * DEVTYPE=usb_interface
167 * INTERFACE=8/6/80
168 * MODALIAS=usb:v18D1p4E12d0227dc00dsc00dp00ic08isc06ip50
169 * PRODUCT=18d1/4e12/227
170 * SUBSYSTEM=usb
171 * TYPE=0/0/0
172 *
173 * ACTION=add
174 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5
175 * DEVTYPE=scsi_host
176 * SUBSYSTEM=scsi
177 *
178 * ACTION=add
179 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/scsi_host/host5
180 * SUBSYSTEM=scsi_host
181 *
182 * ACTION=add
183 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0
184 * DEVTYPE=scsi_target
185 * SUBSYSTEM=scsi
186 *
187 * Case with strange $MODALIAS:
188 * ACTION=add
189 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0
190 * DEVTYPE=scsi_device
191 * MODALIAS=scsi:t-0x00
192 * SUBSYSTEM=scsi
193 *
194 * ACTION=add
195 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0/scsi_disk/5:0:0:0
196 * SUBSYSTEM=scsi_disk
197 *
198 * ACTION=add
199 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0/scsi_device/5:0:0:0
200 * SUBSYSTEM=scsi_device
201 *
202 * Case with explicit $MAJOR/$MINOR (no need to read /sys/$DEVPATH/dev?):
203 * ACTION=add
204 * DEVNAME=bsg/5:0:0:0
205 * DEVPATH=/devices/pci0000:00/0000:00:02.1/usb1/1-5/1-5:1.0/host5/target5:0:0/5:0:0:0/bsg/5:0:0:0
206 * MAJOR=253
207 * MINOR=1
208 * SUBSYSTEM=bsg
209 *
210 * ACTION=add
211 * DEVPATH=/devices/virtual/bdi/8:16
212 * SUBSYSTEM=bdi
213 *
214 * ACTION=add
215 * DEVNAME=sdb
216 * DEVPATH=/block/sdb
217 * DEVTYPE=disk
218 * MAJOR=8
219 * MINOR=16
220 * SUBSYSTEM=block
221 *
222 * Case with ACTION=change:
223 * ACTION=change
224 * DEVNAME=sdb
225 * DEVPATH=/block/sdb
226 * DEVTYPE=disk
227 * DISK_MEDIA_CHANGE=1
228 * MAJOR=8
229 * MINOR=16
230 * SUBSYSTEM=block
231 */
232
233#define DEBUG_LVL 2
234
235#if DEBUG_LVL >= 1
236# define dbg1(...) do { if (G.verbose) bb_error_msg(__VA_ARGS__); } while(0)
237#else
238# define dbg1(...) ((void)0)
239#endif
240#if DEBUG_LVL >= 2
241# define dbg2(...) do { if (G.verbose >= 2) bb_error_msg(__VA_ARGS__); } while(0)
242#else
243# define dbg2(...) ((void)0)
244#endif
245#if DEBUG_LVL >= 3
246# define dbg3(...) do { if (G.verbose >= 3) bb_error_msg(__VA_ARGS__); } while(0)
247#else
248# define dbg3(...) ((void)0)
249#endif
250
251
252static const char keywords[] ALIGN1 = "add\0remove\0"; // "change\0"
253enum { OP_add, OP_remove };
254
255struct envmatch {
256    struct envmatch *next;
257    char *envname;
258    regex_t match;
259};
260
261struct rule {
262    bool keep_matching;
263    bool regex_compiled;
264    mode_t mode;
265    int maj, min0, min1;
266    struct bb_uidgid_t ugid;
267    char *envvar;
268    char *ren_mov;
269    IF_FEATURE_MDEV_EXEC(char *r_cmd;)
270    regex_t match;
271    struct envmatch *envmatch;
272};
273
274struct globals {
275    int root_major, root_minor;
276    smallint verbose;
277    char *subsystem;
278    char *subsys_env; /* for putenv("SUBSYSTEM=subsystem") */
279#if ENABLE_FEATURE_MDEV_CONF
280    const char *filename;
281    parser_t *parser;
282    struct rule **rule_vec;
283    unsigned rule_idx;
284#endif
285    struct rule cur_rule;
286    char timestr[sizeof("60.123456")];
287} FIX_ALIASING;
288#define G (*(struct globals*)&bb_common_bufsiz1)
289#define INIT_G() do { \
290    IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.maj = -1;) \
291    IF_NOT_FEATURE_MDEV_CONF(G.cur_rule.mode = 0660;) \
292} while (0)
293
294
295/* Prevent infinite loops in /sys symlinks */
296#define MAX_SYSFS_DEPTH 3
297
298/* We use additional bytes in make_device() */
299#define SCRATCH_SIZE 128
300
301#if ENABLE_FEATURE_MDEV_CONF
302
303static void make_default_cur_rule(void)
304{
305    memset(&G.cur_rule, 0, sizeof(G.cur_rule));
306    G.cur_rule.maj = -1; /* "not a @major,minor rule" */
307    G.cur_rule.mode = 0660;
308}
309
310static void clean_up_cur_rule(void)
311{
312    struct envmatch *e;
313
314    free(G.cur_rule.envvar);
315    free(G.cur_rule.ren_mov);
316    if (G.cur_rule.regex_compiled)
317        regfree(&G.cur_rule.match);
318    IF_FEATURE_MDEV_EXEC(free(G.cur_rule.r_cmd);)
319    e = G.cur_rule.envmatch;
320    while (e) {
321        free(e->envname);
322        regfree(&e->match);
323        e = e->next;
324    }
325    make_default_cur_rule();
326}
327
328/* In later versions, endofname is in libbb */
329#define endofname mdev_endofname
330static
331const char* FAST_FUNC
332endofname(const char *name)
333{
334#define is_name(c)      ((c) == '_' || isalpha((unsigned char)(c)))
335#define is_in_name(c)   ((c) == '_' || isalnum((unsigned char)(c)))
336    if (!is_name(*name))
337        return name;
338    while (*++name) {
339        if (!is_in_name(*name))
340            break;
341    }
342    return name;
343}
344
345static char *parse_envmatch_pfx(char *val)
346{
347    struct envmatch **nextp = &G.cur_rule.envmatch;
348
349    for (;;) {
350        struct envmatch *e;
351        char *semicolon;
352        char *eq = strchr(val, '=');
353        if (!eq /* || eq == val? */)
354            return val;
355        if (endofname(val) != eq)
356            return val;
357        semicolon = strchr(eq, ';');
358        if (!semicolon)
359            return val;
360        /* ENVVAR=regex;... */
361        *nextp = e = xzalloc(sizeof(*e));
362        nextp = &e->next;
363        e->envname = xstrndup(val, eq - val);
364        *semicolon = '\0';
365        xregcomp(&e->match, eq + 1, REG_EXTENDED);
366        *semicolon = ';';
367        val = semicolon + 1;
368    }
369}
370
371static void parse_next_rule(void)
372{
373    /* Note: on entry, G.cur_rule is set to default */
374    while (1) {
375        char *tokens[4];
376        char *val;
377
378        /* No PARSE_EOL_COMMENTS, because command may contain '#' chars */
379        if (!config_read(G.parser, tokens, 4, 3, "# \t", PARSE_NORMAL & ~PARSE_EOL_COMMENTS))
380            break;
381
382        /* Fields: [-]regex uid:gid mode [alias] [cmd] */
383        dbg3("token1:'%s'", tokens[1]);
384
385        /* 1st field */
386        val = tokens[0];
387        G.cur_rule.keep_matching = ('-' == val[0]);
388        val += G.cur_rule.keep_matching; /* swallow leading dash */
389        val = parse_envmatch_pfx(val);
390        if (val[0] == '@') {
391            /* @major,minor[-minor2] */
392            /* (useful when name is ambiguous:
393             * "/sys/class/usb/lp0" and
394             * "/sys/class/printer/lp0")
395             */
396            int sc = sscanf(val, "@%u,%u-%u", &G.cur_rule.maj, &G.cur_rule.min0, &G.cur_rule.min1);
397            if (sc < 2 || G.cur_rule.maj < 0) {
398                bb_error_msg("bad @maj,min on line %d", G.parser->lineno);
399                goto next_rule;
400            }
401            if (sc == 2)
402                G.cur_rule.min1 = G.cur_rule.min0;
403        } else {
404            char *eq = strchr(val, '=');
405            if (val[0] == '$') {
406                /* $ENVVAR=regex ... */
407                val++;
408                if (!eq) {
409                    bb_error_msg("bad $envvar=regex on line %d", G.parser->lineno);
410                    goto next_rule;
411                }
412                G.cur_rule.envvar = xstrndup(val, eq - val);
413                val = eq + 1;
414            }
415            xregcomp(&G.cur_rule.match, val, REG_EXTENDED);
416            G.cur_rule.regex_compiled = 1;
417        }
418
419        /* 2nd field: uid:gid - device ownership */
420        if (get_uidgid(&G.cur_rule.ugid, tokens[1], /*allow_numeric:*/ 1) == 0) {
421            bb_error_msg("unknown user/group '%s' on line %d", tokens[1], G.parser->lineno);
422            goto next_rule;
423        }
424
425        /* 3rd field: mode - device permissions */
426        bb_parse_mode(tokens[2], &G.cur_rule.mode);
427
428        /* 4th field (opt): ">|=alias" or "!" to not create the node */
429        val = tokens[3];
430        if (ENABLE_FEATURE_MDEV_RENAME && val && strchr(">=!", val[0])) {
431            char *s = skip_non_whitespace(val);
432            G.cur_rule.ren_mov = xstrndup(val, s - val);
433            val = skip_whitespace(s);
434        }
435
436        if (ENABLE_FEATURE_MDEV_EXEC && val && val[0]) {
437            const char *s = "$@*";
438            const char *s2 = strchr(s, val[0]);
439            if (!s2) {
440                bb_error_msg("bad line %u", G.parser->lineno);
441                goto next_rule;
442            }
443            IF_FEATURE_MDEV_EXEC(G.cur_rule.r_cmd = xstrdup(val);)
444        }
445
446        return;
447 next_rule:
448        clean_up_cur_rule();
449    } /* while (config_read) */
450
451    dbg3("config_close(G.parser)");
452    config_close(G.parser);
453    G.parser = NULL;
454
455    return;
456}
457
458/* If mdev -s, we remember rules in G.rule_vec[].
459 * Otherwise, there is no point in doing it, and we just
460 * save only one parsed rule in G.cur_rule.
461 */
462static const struct rule *next_rule(void)
463{
464    struct rule *rule;
465
466    /* Open conf file if we didn't do it yet */
467    if (!G.parser && G.filename) {
468        dbg3("config_open('%s')", G.filename);
469        G.parser = config_open2(G.filename, fopen_for_read);
470        G.filename = NULL;
471    }
472
473    if (G.rule_vec) {
474        /* mdev -s */
475        /* Do we have rule parsed already? */
476        if (G.rule_vec[G.rule_idx]) {
477            dbg3("< G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
478            return G.rule_vec[G.rule_idx++];
479        }
480        make_default_cur_rule();
481    } else {
482        /* not mdev -s */
483        clean_up_cur_rule();
484    }
485
486    /* Parse one more rule if file isn't fully read */
487    rule = &G.cur_rule;
488    if (G.parser) {
489        parse_next_rule();
490        if (G.rule_vec) { /* mdev -s */
491            rule = memcpy(xmalloc(sizeof(G.cur_rule)), &G.cur_rule, sizeof(G.cur_rule));
492            G.rule_vec = xrealloc_vector(G.rule_vec, 4, G.rule_idx);
493            G.rule_vec[G.rule_idx++] = rule;
494            dbg3("> G.rule_vec[G.rule_idx:%d]=%p", G.rule_idx, G.rule_vec[G.rule_idx]);
495        }
496    }
497
498    return rule;
499}
500
501static int env_matches(struct envmatch *e)
502{
503    while (e) {
504        int r;
505        char *val = getenv(e->envname);
506        if (!val)
507            return 0;
508        r = regexec(&e->match, val, /*size*/ 0, /*range[]*/ NULL, /*eflags*/ 0);
509        if (r != 0) /* no match */
510            return 0;
511        e = e->next;
512    }
513    return 1;
514}
515
516#else
517
518# define next_rule() (&G.cur_rule)
519
520#endif
521
522static void mkdir_recursive(char *name)
523{
524    /* if name has many levels ("dir1/dir2"),
525     * bb_make_directory() will create dir1 according to umask,
526     * not according to its "mode" parameter.
527     * Since we run with umask=0, need to temporarily switch it.
528     */
529    umask(022); /* "dir1" (if any) will be 0755 too */
530    bb_make_directory(name, 0755, FILEUTILS_RECUR);
531    umask(0);
532}
533
534/* Builds an alias path.
535 * This function potentionally reallocates the alias parameter.
536 * Only used for ENABLE_FEATURE_MDEV_RENAME
537 */
538static char *build_alias(char *alias, const char *device_name)
539{
540    char *dest;
541
542    /* ">bar/": rename to bar/device_name */
543    /* ">bar[/]baz": rename to bar[/]baz */
544    dest = strrchr(alias, '/');
545    if (dest) { /* ">bar/[baz]" ? */
546        *dest = '\0'; /* mkdir bar */
547        mkdir_recursive(alias);
548        *dest = '/';
549        if (dest[1] == '\0') { /* ">bar/" => ">bar/device_name" */
550            dest = alias;
551            alias = concat_path_file(alias, device_name);
552            free(dest);
553        }
554    }
555
556    return alias;
557}
558
559/* mknod in /dev based on a path like "/sys/block/hda/hda1"
560 * NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
561 * after NUL, but we promise to not mangle (IOW: to restore NUL if needed)
562 * path string.
563 * NB2: "mdev -s" may call us many times, do not leak memory/fds!
564 *
565 * device_name = $DEVNAME (may be NULL)
566 * path        = /sys/$DEVPATH
567 */
568static void make_device(char *device_name, char *path, int operation)
569{
570    int major, minor, type, len;
571    char *path_end = path + strlen(path);
572
573    /* Try to read major/minor string.  Note that the kernel puts \n after
574     * the data, so we don't need to worry about null terminating the string
575     * because sscanf() will stop at the first nondigit, which \n is.
576     * We also depend on path having writeable space after it.
577     */
578    major = -1;
579    if (operation == OP_add) {
580        strcpy(path_end, "/dev");
581        len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
582        *path_end = '\0';
583        if (len < 1) {
584            if (!ENABLE_FEATURE_MDEV_EXEC)
585                return;
586            /* no "dev" file, but we can still run scripts
587             * based on device name */
588        } else if (sscanf(path_end + 1, "%u:%u", &major, &minor) == 2) {
589            dbg1("dev %u,%u", major, minor);
590        } else {
591            major = -1;
592        }
593    }
594    /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
595
596    /* Determine device name */
597    if (!device_name) {
598        /*
599         * There was no $DEVNAME envvar (for example, mdev -s never has).
600         * But it is very useful: it contains the *path*, not only basename,
601         * Thankfully, uevent file has it.
602         * Example of .../sound/card0/controlC0/uevent file on Linux-3.7.7:
603         * MAJOR=116
604         * MINOR=7
605         * DEVNAME=snd/controlC0
606         */
607        strcpy(path_end, "/uevent");
608        len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
609        if (len < 0)
610            len = 0;
611        *path_end = '\0';
612        path_end[1 + len] = '\0';
613        device_name = strstr(path_end + 1, "\nDEVNAME=");
614        if (device_name) {
615            device_name += sizeof("\nDEVNAME=")-1;
616            strchrnul(device_name, '\n')[0] = '\0';
617        } else {
618            /* Fall back to just basename */
619            device_name = (char*) bb_basename(path);
620        }
621    }
622    /* Determine device type */
623    /*
624     * http://kernel.org/doc/pending/hotplug.txt says that only
625     * "/sys/block/..." is for block devices. "/sys/bus" etc is not.
626     * But since 2.6.25 block devices are also in /sys/class/block.
627     * We use strstr("/block/") to forestall future surprises.
628     */
629    type = S_IFCHR;
630    if (strstr(path, "/block/") || (G.subsystem && strncmp(G.subsystem, "block", 5) == 0))
631        type = S_IFBLK;
632
633#if ENABLE_FEATURE_MDEV_CONF
634    G.rule_idx = 0; /* restart from the beginning (think mdev -s) */
635#endif
636    for (;;) {
637        const char *str_to_match;
638        regmatch_t off[1 + 9 * ENABLE_FEATURE_MDEV_RENAME_REGEXP];
639        char *command;
640        char *alias;
641        char aliaslink = aliaslink; /* for compiler */
642        char *node_name;
643        const struct rule *rule;
644
645        str_to_match = device_name;
646
647        rule = next_rule();
648
649#if ENABLE_FEATURE_MDEV_CONF
650        if (!env_matches(rule->envmatch))
651            continue;
652        if (rule->maj >= 0) {  /* @maj,min rule */
653            if (major != rule->maj)
654                continue;
655            if (minor < rule->min0 || minor > rule->min1)
656                continue;
657            memset(off, 0, sizeof(off));
658            goto rule_matches;
659        }
660        if (rule->envvar) { /* $envvar=regex rule */
661            str_to_match = getenv(rule->envvar);
662            dbg3("getenv('%s'):'%s'", rule->envvar, str_to_match);
663            if (!str_to_match)
664                continue;
665        }
666        /* else: str_to_match = device_name */
667
668        if (rule->regex_compiled) {
669            int regex_match = regexec(&rule->match, str_to_match, ARRAY_SIZE(off), off, 0);
670            dbg3("regex_match for '%s':%d", str_to_match, regex_match);
671            //bb_error_msg("matches:");
672            //for (int i = 0; i < ARRAY_SIZE(off); i++) {
673            //  if (off[i].rm_so < 0) continue;
674            //  bb_error_msg("match %d: '%.*s'\n", i,
675            //      (int)(off[i].rm_eo - off[i].rm_so),
676            //      device_name + off[i].rm_so);
677            //}
678
679            if (regex_match != 0
680            /* regexec returns whole pattern as "range" 0 */
681             || off[0].rm_so != 0
682             || (int)off[0].rm_eo != (int)strlen(str_to_match)
683            ) {
684                continue; /* this rule doesn't match */
685            }
686        }
687        /* else: it's final implicit "match-all" rule */
688 rule_matches:
689        dbg2("rule matched, line %d", G.parser ? G.parser->lineno : -1);
690#endif
691        /* Build alias name */
692        alias = NULL;
693        if (ENABLE_FEATURE_MDEV_RENAME && rule->ren_mov) {
694            aliaslink = rule->ren_mov[0];
695            if (aliaslink == '!') {
696                /* "!": suppress node creation/deletion */
697                major = -2;
698            }
699            else if (aliaslink == '>' || aliaslink == '=') {
700                if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
701                    char *s;
702                    char *p;
703                    unsigned n;
704
705                    /* substitute %1..9 with off[1..9], if any */
706                    n = 0;
707                    s = rule->ren_mov;
708                    while (*s)
709                        if (*s++ == '%')
710                            n++;
711
712                    p = alias = xzalloc(strlen(rule->ren_mov) + n * strlen(str_to_match));
713                    s = rule->ren_mov + 1;
714                    while (*s) {
715                        *p = *s;
716                        if ('%' == *s) {
717                            unsigned i = (s[1] - '0');
718                            if (i <= 9 && off[i].rm_so >= 0) {
719                                n = off[i].rm_eo - off[i].rm_so;
720                                strncpy(p, str_to_match + off[i].rm_so, n);
721                                p += n - 1;
722                                s++;
723                            }
724                        }
725                        p++;
726                        s++;
727                    }
728                } else {
729                    alias = xstrdup(rule->ren_mov + 1);
730                }
731            }
732        }
733        dbg3("alias:'%s'", alias);
734
735        command = NULL;
736        IF_FEATURE_MDEV_EXEC(command = rule->r_cmd;)
737        if (command) {
738            /* Are we running this command now?
739             * Run @cmd on create, $cmd on delete, *cmd on any
740             */
741            if ((command[0] == '@' && operation == OP_add)
742             || (command[0] == '$' && operation == OP_remove)
743             || (command[0] == '*')
744            ) {
745                command++;
746            } else {
747                command = NULL;
748            }
749        }
750        dbg3("command:'%s'", command);
751
752        /* "Execute" the line we found */
753        node_name = device_name;
754        if (ENABLE_FEATURE_MDEV_RENAME && alias) {
755            node_name = alias = build_alias(alias, device_name);
756            dbg3("alias2:'%s'", alias);
757        }
758
759        if (operation == OP_add && major >= 0) {
760            char *slash = strrchr(node_name, '/');
761            if (slash) {
762                *slash = '\0';
763                mkdir_recursive(node_name);
764                *slash = '/';
765            }
766            if (ENABLE_FEATURE_MDEV_CONF) {
767                dbg1("mknod %s (%d,%d) %o"
768                    " %u:%u",
769                    node_name, major, minor, rule->mode | type,
770                    rule->ugid.uid, rule->ugid.gid
771                );
772            } else {
773                dbg1("mknod %s (%d,%d) %o",
774                    node_name, major, minor, rule->mode | type
775                );
776            }
777            if (mknod(node_name, rule->mode | type, makedev(major, minor)) && errno != EEXIST)
778                bb_perror_msg("can't create '%s'", node_name);
779            if (ENABLE_FEATURE_MDEV_CONF) {
780                chmod(node_name, rule->mode);
781                chown(node_name, rule->ugid.uid, rule->ugid.gid);
782            }
783            if (major == G.root_major && minor == G.root_minor)
784                symlink(node_name, "root");
785            if (ENABLE_FEATURE_MDEV_RENAME && alias) {
786                if (aliaslink == '>') {
787//TODO: on devtmpfs, device_name already exists and symlink() fails.
788//End result is that instead of symlink, we have two nodes.
789//What should be done?
790                    dbg1("symlink: %s", device_name);
791                    symlink(node_name, device_name);
792                }
793            }
794        }
795
796        if (ENABLE_FEATURE_MDEV_EXEC && command) {
797            /* setenv will leak memory, use putenv/unsetenv/free */
798            char *s = xasprintf("%s=%s", "MDEV", node_name);
799            putenv(s);
800            dbg1("running: %s", command);
801            if (system(command) == -1)
802                bb_perror_msg("can't run '%s'", command);
803            bb_unsetenv_and_free(s);
804        }
805
806        if (operation == OP_remove && major >= -1) {
807            if (ENABLE_FEATURE_MDEV_RENAME && alias) {
808                if (aliaslink == '>') {
809                    dbg1("unlink: %s", device_name);
810                    unlink(device_name);
811                }
812            }
813            dbg1("unlink: %s", node_name);
814            unlink(node_name);
815        }
816
817        if (ENABLE_FEATURE_MDEV_RENAME)
818            free(alias);
819
820        /* We found matching line.
821         * Stop unless it was prefixed with '-'
822         */
823        if (!ENABLE_FEATURE_MDEV_CONF || !rule->keep_matching)
824            break;
825    } /* for (;;) */
826}
827
828/* File callback for /sys/ traversal */
829static int FAST_FUNC fileAction(const char *fileName,
830        struct stat *statbuf UNUSED_PARAM,
831        void *userData,
832        int depth UNUSED_PARAM)
833{
834    size_t len = strlen(fileName) - 4; /* can't underflow */
835    char *scratch = userData;
836
837    /* len check is for paranoid reasons */
838    if (strcmp(fileName + len, "/dev") != 0 || len >= PATH_MAX)
839        return FALSE;
840
841    strcpy(scratch, fileName);
842    scratch[len] = '\0';
843    make_device(/*DEVNAME:*/ NULL, scratch, OP_add);
844
845    return TRUE;
846}
847
848/* Directory callback for /sys/ traversal */
849static int FAST_FUNC dirAction(const char *fileName UNUSED_PARAM,
850        struct stat *statbuf UNUSED_PARAM,
851        void *userData UNUSED_PARAM,
852        int depth)
853{
854    /* Extract device subsystem -- the name of the directory
855     * under /sys/class/ */
856    if (1 == depth) {
857        free(G.subsystem);
858        if (G.subsys_env) {
859            bb_unsetenv_and_free(G.subsys_env);
860            G.subsys_env = NULL;
861        }
862        G.subsystem = strrchr(fileName, '/');
863        if (G.subsystem) {
864            G.subsystem = xstrdup(G.subsystem + 1);
865            G.subsys_env = xasprintf("%s=%s", "SUBSYSTEM", G.subsystem);
866            putenv(G.subsys_env);
867        }
868    }
869
870    return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
871}
872
873/* For the full gory details, see linux/Documentation/firmware_class/README
874 *
875 * Firmware loading works like this:
876 * - kernel sets FIRMWARE env var
877 * - userspace checks /lib/firmware/$FIRMWARE
878 * - userspace waits for /sys/$DEVPATH/loading to appear
879 * - userspace writes "1" to /sys/$DEVPATH/loading
880 * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
881 * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
882 * - kernel loads firmware into device
883 */
884static void load_firmware(const char *firmware, const char *sysfs_path)
885{
886    int cnt;
887    int firmware_fd, loading_fd;
888
889    /* check for /lib/firmware/$FIRMWARE */
890    xchdir("/lib/firmware");
891    firmware_fd = open(firmware, O_RDONLY); /* can fail */
892
893    /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
894    xchdir(sysfs_path);
895    for (cnt = 0; cnt < 30; ++cnt) {
896        loading_fd = open("loading", O_WRONLY);
897        if (loading_fd >= 0)
898            goto loading;
899        sleep(1);
900    }
901    goto out;
902
903 loading:
904    cnt = 0;
905    if (firmware_fd >= 0) {
906        int data_fd;
907
908        /* tell kernel we're loading by "echo 1 > /sys/$DEVPATH/loading" */
909        if (full_write(loading_fd, "1", 1) != 1)
910            goto out;
911
912        /* load firmware into /sys/$DEVPATH/data */
913        data_fd = open("data", O_WRONLY);
914        if (data_fd < 0)
915            goto out;
916        cnt = bb_copyfd_eof(firmware_fd, data_fd);
917        if (ENABLE_FEATURE_CLEAN_UP)
918            close(data_fd);
919    }
920
921    /* Tell kernel result by "echo [0|-1] > /sys/$DEVPATH/loading"
922     * Note: we emit -1 also if firmware file wasn't found.
923     * There are cases when otherwise kernel would wait for minutes
924     * before timing out.
925     */
926    if (cnt > 0)
927        full_write(loading_fd, "0", 1);
928    else
929        full_write(loading_fd, "-1", 2);
930
931 out:
932    xchdir("/dev");
933    if (ENABLE_FEATURE_CLEAN_UP) {
934        close(firmware_fd);
935        close(loading_fd);
936    }
937}
938
939static char *curtime(void)
940{
941    struct timeval tv;
942    gettimeofday(&tv, NULL);
943    sprintf(G.timestr, "%u.%06u", (unsigned)tv.tv_sec % 60, (unsigned)tv.tv_usec);
944    return G.timestr;
945}
946
947static void open_mdev_log(const char *seq, unsigned my_pid)
948{
949    int logfd = open("mdev.log", O_WRONLY | O_APPEND);
950    if (logfd >= 0) {
951        xmove_fd(logfd, STDERR_FILENO);
952        G.verbose = 2;
953        applet_name = xasprintf("%s[%s]", applet_name, seq ? seq : utoa(my_pid));
954    }
955}
956
957/* If it exists, does /dev/mdev.seq match $SEQNUM?
958 * If it does not match, earlier mdev is running
959 * in parallel, and we need to wait.
960 * Active mdev pokes us with SIGCHLD to check the new file.
961 */
962static int
963wait_for_seqfile(const char *seq)
964{
965    /* We time out after 2 sec */
966    static const struct timespec ts = { 0, 32*1000*1000 };
967    int timeout = 2000 / 32;
968    int seq_fd = -1;
969    int do_once = 1;
970    sigset_t set_CHLD;
971
972    sigemptyset(&set_CHLD);
973    sigaddset(&set_CHLD, SIGCHLD);
974    sigprocmask(SIG_BLOCK, &set_CHLD, NULL);
975
976    for (;;) {
977        int seqlen;
978        char seqbuf[sizeof(int)*3 + 2];
979
980        if (seq_fd < 0) {
981            seq_fd = open("mdev.seq", O_RDWR);
982            if (seq_fd < 0)
983                break;
984        }
985        seqlen = pread(seq_fd, seqbuf, sizeof(seqbuf) - 1, 0);
986        if (seqlen < 0) {
987            close(seq_fd);
988            seq_fd = -1;
989            break;
990        }
991        seqbuf[seqlen] = '\0';
992        if (seqbuf[0] == '\n') {
993            /* seed file: write out seq ASAP */
994            xwrite_str(seq_fd, seq);
995            xlseek(seq_fd, 0, SEEK_SET);
996            dbg2("first seq written");
997            break;
998        }
999        if (strcmp(seq, seqbuf) == 0) {
1000            /* correct idx */
1001            break;
1002        }
1003        if (do_once) {
1004            dbg2("%s waiting for '%s'", curtime(), seqbuf);
1005            do_once = 0;
1006        }
1007        if (sigtimedwait(&set_CHLD, NULL, &ts) >= 0) {
1008            dbg3("woken up");
1009            continue; /* don't decrement timeout! */
1010        }
1011        if (--timeout == 0) {
1012            dbg1("%s waiting for '%s'", "timed out", seqbuf);
1013            break;
1014        }
1015    }
1016    sigprocmask(SIG_UNBLOCK, &set_CHLD, NULL);
1017    return seq_fd;
1018}
1019
1020static void signal_mdevs(unsigned my_pid)
1021{
1022    procps_status_t* p = NULL;
1023    while ((p = procps_scan(p, PSSCAN_ARGV0)) != NULL) {
1024        if (p->pid != my_pid
1025         && p->argv0
1026         && strcmp(bb_basename(p->argv0), "mdev") == 0
1027        ) {
1028            kill(p->pid, SIGCHLD);
1029        }
1030    }
1031}
1032
1033int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1034int mdev_main(int argc UNUSED_PARAM, char **argv)
1035{
1036    RESERVE_CONFIG_BUFFER(temp, PATH_MAX + SCRATCH_SIZE);
1037
1038    INIT_G();
1039
1040#if ENABLE_FEATURE_MDEV_CONF
1041    G.filename = "/etc/mdev.conf";
1042#endif
1043
1044    /* We can be called as hotplug helper */
1045    /* Kernel cannot provide suitable stdio fds for us, do it ourself */
1046    bb_sanitize_stdio();
1047
1048    /* Force the configuration file settings exactly */
1049    umask(0);
1050
1051    xchdir("/dev");
1052
1053    if (argv[1] && strcmp(argv[1], "-s") == 0) {
1054        /*
1055         * Scan: mdev -s
1056         */
1057        struct stat st;
1058
1059#if ENABLE_FEATURE_MDEV_CONF
1060        /* Same as xrealloc_vector(NULL, 4, 0): */
1061        G.rule_vec = xzalloc((1 << 4) * sizeof(*G.rule_vec));
1062#endif
1063        xstat("/", &st);
1064        G.root_major = major(st.st_dev);
1065        G.root_minor = minor(st.st_dev);
1066
1067        putenv((char*)"ACTION=add");
1068
1069        /* ACTION_FOLLOWLINKS is needed since in newer kernels
1070         * /sys/block/loop* (for example) are symlinks to dirs,
1071         * not real directories.
1072         * (kernel's CONFIG_SYSFS_DEPRECATED makes them real dirs,
1073         * but we can't enforce that on users)
1074         */
1075        if (access("/sys/class/block", F_OK) != 0) {
1076            /* Scan obsolete /sys/block only if /sys/class/block
1077             * doesn't exist. Otherwise we'll have dupes.
1078             * Also, do not complain if it doesn't exist.
1079             * Some people configure kernel to have no blockdevs.
1080             */
1081            recursive_action("/sys/block",
1082                ACTION_RECURSE | ACTION_FOLLOWLINKS | ACTION_QUIET,
1083                fileAction, dirAction, temp, 0);
1084        }
1085        recursive_action("/sys/class",
1086            ACTION_RECURSE | ACTION_FOLLOWLINKS,
1087            fileAction, dirAction, temp, 0);
1088    } else {
1089        char *fw;
1090        char *seq;
1091        char *action;
1092        char *env_devname;
1093        char *env_devpath;
1094        unsigned my_pid;
1095        int seq_fd;
1096        smalluint op;
1097
1098        /* Hotplug:
1099         * env ACTION=... DEVPATH=... SUBSYSTEM=... [SEQNUM=...] mdev
1100         * ACTION can be "add", "remove", "change"
1101         * DEVPATH is like "/block/sda" or "/class/input/mice"
1102         */
1103        action = getenv("ACTION");
1104        op = index_in_strings(keywords, action);
1105        env_devname = getenv("DEVNAME"); /* can be NULL */
1106        env_devpath = getenv("DEVPATH");
1107        G.subsystem = getenv("SUBSYSTEM");
1108        if (!action || !env_devpath /*|| !G.subsystem*/)
1109            bb_show_usage();
1110        fw = getenv("FIRMWARE");
1111        seq = getenv("SEQNUM");
1112
1113        my_pid = getpid();
1114        open_mdev_log(seq, my_pid);
1115
1116        seq_fd = seq ? wait_for_seqfile(seq) : -1;
1117
1118        dbg1("%s "
1119            "ACTION:%s SUBSYSTEM:%s DEVNAME:%s DEVPATH:%s"
1120            "%s%s",
1121            curtime(),
1122            action, G.subsystem, env_devname, env_devpath,
1123            fw ? " FW:" : "", fw ? fw : ""
1124        );
1125
1126        snprintf(temp, PATH_MAX, "/sys%s", env_devpath);
1127        if (op == OP_remove) {
1128            /* Ignoring "remove firmware". It was reported
1129             * to happen and to cause erroneous deletion
1130             * of device nodes. */
1131            if (!fw)
1132                make_device(env_devname, temp, op);
1133        }
1134        else {
1135            make_device(env_devname, temp, op);
1136            if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE) {
1137                if (op == OP_add && fw)
1138                    load_firmware(fw, temp);
1139            }
1140        }
1141
1142        dbg1("%s exiting", curtime());
1143        if (seq_fd >= 0) {
1144            xwrite_str(seq_fd, utoa(xatou(seq) + 1));
1145            signal_mdevs(my_pid);
1146        }
1147    }
1148
1149    if (ENABLE_FEATURE_CLEAN_UP)
1150        RELEASE_CONFIG_BUFFER(temp);
1151
1152    return EXIT_SUCCESS;
1153}
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