aboutsummaryrefslogtreecommitdiff
path: root/toys/pending/mdev.c
blob: d0bb0681ab529d79b4274fc10e829cbf27af6bad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
/* mdev.c - Populate /dev directory and handle hotplug events
 *
 * Copyright 2005, 2008 Rob Landley <rob@landley.net>
 * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>

USE_MDEV(NEWTOY(mdev, "s", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_UMASK))

config MDEV
  bool "mdev"
  default n
  help
    usage: mdev [-s]

    Create devices in /dev using information from /sys.

    -s	Scan all entries in /sys to populate /dev

config MDEV_CONF
  bool "Configuration file for mdev"
  default y
  depends on MDEV
  help
    The mdev config file (/etc/mdev.conf) contains lines that look like:
    hd[a-z][0-9]* 0:3 660
    (sd[a-z]) root:disk 660 =usb_storage

    Each line must contain three whitespace separated fields. The first
    field is a regular expression matching one or more device names,
    the second and third fields are uid:gid and file permissions for
    matching devices. Fourth field is optional. It could be used to change
    device name (prefix '='), path (prefix '=' and postfix '/') or create a
    symlink (prefix '>').
*/

#include "toys.h"
#include <stdbool.h>

// mknod in /dev based on a path like "/sys/block/hda/hda1"
static void make_device(char *path)
{
  char *device_name = 0, *custom_name = 0, *s, *temp;
  bool create_symlink = false;
  int major = 0, minor = 0, type, len, fd, mode = 0660;
  uid_t uid = 0;
  gid_t gid = 0;

  if (path) {

    // Try to read major/minor string, returning if we can't
    temp = strrchr(path, '/');
    fd = open(path, O_RDONLY);
    *temp = 0;
    len = read(fd, toybuf, 64);
    close(fd);
    if (len<1) return;
    toybuf[len] = 0;

    // Determine device type, major and minor

    type = path[5]=='c' ? S_IFCHR : S_IFBLK;
    sscanf(toybuf, "%u:%u", &major, &minor);
  } else {
    // if (!path), do hotplug

    if (!(temp = getenv("MODALIAS"))) xrun((char *[]){"modprobe", temp, 0});
    if (!(temp = getenv("SUBSYSTEM"))) return;
    type = strcmp(temp, "block") ? S_IFCHR : S_IFBLK;
    if (!(temp = getenv("MAJOR"))) return;
    sscanf(temp, "%u", &major);
    if (!(temp = getenv("MINOR"))) return;
    sscanf(temp, "%u", &minor);
    if (!(path = getenv("DEVPATH"))) return;
    device_name = getenv("DEVNAME");
  }
  if (!device_name)
    device_name = strrchr(path, '/') + 1;

  // as in linux/drivers/base/core.c, device_get_devnode()
  while ((temp = strchr(device_name, '!'))) {
    *temp = '/';
  }

  // If we have a config file, look up permissions for this device

  if (CFG_MDEV_CONF) {
    char *conf, *pos, *end;
    bool optional_field_valid = false;

    // mmap the config file
    if (-1!=(fd = open("/etc/mdev.conf", O_RDONLY))) {
      int line = 0;

      len = fdlength(fd);
      conf = xmmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);

      // Loop through lines in mmaped file
      for (pos = conf; pos-conf<len;) {
        int field;
        char *end2;

        line++;
        // find end of this line
        for(end = pos; end-conf<len && *end!='\n'; end++);

        // Four fields (last is optional): regex, uid:gid, mode [, name|path ]
	// For example: (sd[a-z])1  root:disk 660 =usb_storage_p1
        for (field = 4; field; field--) {
          // Skip whitespace
          while (pos<end && isspace(*pos)) pos++;
          if (pos==end || *pos=='#') break;
          for (end2 = pos;
            end2<end && !isspace(*end2) && *end2!='#'; end2++);
          switch(field) {
            // Regex to match this device
            case 4:
            {
              char *regex = strndup(pos, end2-pos);
              regex_t match;
              regmatch_t off;
              int result;

              // Is this it?
              xregcomp(&match, regex, REG_EXTENDED);
              result=regexec(&match, device_name, 1, &off, 0);
              regfree(&match);
              free(regex);

              // If not this device, skip rest of line
              if (result || off.rm_so
                || off.rm_eo!=strlen(device_name))
                  goto end_line;

              break;
            }
            // uid:gid
            case 3:
            {
              char *s2;

              // Find :
              for(s = pos; s<end2 && *s!=':'; s++);
              if (s==end2) goto end_line;

              // Parse UID
              uid = strtoul(pos,&s2,10);
              if (s!=s2) {
                struct passwd *pass;
                char *str = strndup(pos, s-pos);
                pass = getpwnam(str);
                free(str);
                if (!pass) goto end_line;
                uid = pass->pw_uid;
              }
              s++;
              // parse GID
              gid = strtoul(s,&s2,10);
              if (end2!=s2) {
                struct group *grp;
                char *str = strndup(s, end2-s);
                grp = getgrnam(str);
                free(str);
                if (!grp) goto end_line;
                gid = grp->gr_gid;
              }
              break;
            }
            // mode
            case 2:
            {
              char *beg_pos = pos;
              mode = strtoul(pos, &pos, 8);
	      if(pos == beg_pos) {
                // The line is bad because mode setting could not be
                // converted to numeric value.
                goto end_line;
	      }
              break;
            }
            // Try to look for name or path (optional field)
            case 1:
            {
              if(pos < end2){
                //char *name = strndup(pos, end2-pos);
                char *name = malloc(end2-pos+1);
                if(name){
                  strncpy(name, pos, end2-pos+1);
                  name[end2-pos] = '\0';
                  switch(name[0]){
                    case '>':
                      create_symlink = true;
                    case '=':
                      custom_name = strdup(&name[1]);
                      break;
                    case '!':
                      device_name = NULL;
                      break;
                    default:
                      free(name);
                      goto end_line;
                  }
                  free(name);
                  optional_field_valid = true;
                }
              }
              goto found_device;
            }
          }
          pos=end2;
        }
end_line:
        // Did everything parse happily?
        // Note: Last field is optional.
        if ((field>1 || (field==1 && !optional_field_valid)) && field!=4)
          error_exit("Bad line %d", line);
        // Next line
        pos = ++end;
      }
found_device:
      munmap(conf, len);
    }
    close(fd);
  }

  if(device_name) {
    if(custom_name) {
      sprintf(toybuf, "/dev/%s", custom_name);
      if(custom_name[strlen(custom_name) - 1] == '/') {
        DIR *dir;
        dir = opendir(toybuf);
        if(dir) closedir(dir);
        else mkdir(toybuf, 0755);
      }
    }
    else
      sprintf(toybuf, "/dev/%s", device_name);

      if ((temp=getenv("ACTION")) && !strcmp(temp, "remove")) {
        unlink(toybuf);
        return;
      }

      if (strchr(device_name, '/')) mkpath(toybuf);
      if (mknod(toybuf, mode | type, dev_makedev(major, minor)) &&
          errno != EEXIST)
        perror_exit("mknod %s failed", toybuf);
      if(create_symlink){
        char *symlink_name = malloc(sizeof("/dev/") + strlen(device_name) + 1);
        if(symlink_name == NULL)
          perror_exit("malloc failed while creating symlink to %s", toybuf);
        sprintf(symlink_name, "/dev/%s", device_name);
        if(symlink(toybuf, symlink_name)){
          free(symlink_name);
          perror_exit("symlink creation failed for %s", toybuf);
        }
        free(symlink_name);
      }

      if (type == S_IFBLK) close(open(toybuf, O_RDONLY)); // scan for partitions

      if (CFG_MDEV_CONF) mode=chown(toybuf, uid, gid);
  }
}

static int callback(struct dirtree *node)
{
  // Entries in /sys/class/block aren't char devices, so skip 'em.  (We'll
  // get block devices out of /sys/block.)
  if(!strcmp(node->name, "block")) return 0;

  // Does this directory have a "dev" entry in it?
  // This is path based because the hotplug callbacks are
  if (S_ISDIR(node->st.st_mode) || S_ISLNK(node->st.st_mode)) {
    int len=4;
    char *dev = dirtree_path(node, &len);
    strcpy(dev+len, "/dev");
    if (!access(dev, R_OK)) make_device(dev);
    free(dev);
  }

  // Circa 2.6.25 the entries more than 2 deep are all either redundant
  // (mouse#, event#) or unnamed (every usb_* entry is called "device").

  if (node->parent && node->parent->parent) return 0;
  return DIRTREE_RECURSE|DIRTREE_SYMFOLLOW;
}

void mdev_main(void)
{
  // Handle -s

  if (toys.optflags) {
    dirtree_read("/sys/class", callback);
    if (!access("/sys/block", R_OK)) dirtree_read("/sys/block", callback);
  } else { // hotplug support
    make_device(NULL);
  }
}