1/* mdev.c - Populate /dev directory and handle hotplug events
2 *
3 * Copyright 2005, 2008 Rob Landley <rob@landley.net>
4 * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
5
6USE_MDEV(NEWTOY(mdev, "s", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_UMASK))
7
8config MDEV
9  bool "mdev"
10  default n
11  help
12    usage: mdev [-s]
13
14    Create devices in /dev using information from /sys.
15
16    -s	Scan all entries in /sys to populate /dev
17
18config MDEV_CONF
19  bool "Configuration file for mdev"
20  default y
21  depends on MDEV
22  help
23    The mdev config file (/etc/mdev.conf) contains lines that look like:
24    hd[a-z][0-9]* 0:3 660
25
26    Each line must contain three whitespace separated fields. The first
27    field is a regular expression matching one or more device names,
28    the second and third fields are uid:gid and file permissions for
29    matching devies.
30*/
31
32#include "toys.h"
33
34// mknod in /dev based on a path like "/sys/block/hda/hda1"
35static void make_device(char *path)
36{
37  char *device_name = 0, *s, *temp;
38  int major = 0, minor = 0, type, len, fd, mode = 0660;
39  uid_t uid = 0;
40  gid_t gid = 0;
41
42  if (path) {
43
44    // Try to read major/minor string, returning if we can't
45    temp = strrchr(path, '/');
46    fd = open(path, O_RDONLY);
47    *temp = 0;
48    len = read(fd, toybuf, 64);
49    close(fd);
50    if (len<1) return;
51    toybuf[len] = 0;
52
53    // Determine device type, major and minor
54
55    type = path[5]=='c' ? S_IFCHR : S_IFBLK;
56    sscanf(toybuf, "%u:%u", &major, &minor);
57  } else {
58    // if (!path), do hotplug
59
60    if (!(temp = getenv("MODALIAS"))) xrun((char *[]){"modprobe", temp, 0});
61    if (!(temp = getenv("SUBSYSTEM"))) return;
62    type = strcmp(temp, "block") ? S_IFCHR : S_IFBLK;
63    if (!(temp = getenv("MAJOR"))) return;
64    sscanf(temp, "%u", &major);
65    if (!(temp = getenv("MINOR"))) return;
66    sscanf(temp, "%u", &minor);
67    if (!(path = getenv("DEVPATH"))) return;
68    device_name = getenv("DEVNAME");
69  }
70  if (!device_name)
71    device_name = strrchr(path, '/') + 1;
72
73  // as in linux/drivers/base/core.c, device_get_devnode()
74  while ((temp = strchr(device_name, '!'))) {
75    *temp = '/';
76  }
77
78  // If we have a config file, look up permissions for this device
79
80  if (CFG_MDEV_CONF) {
81    char *conf, *pos, *end;
82
83    // mmap the config file
84    if (-1!=(fd = open("/etc/mdev.conf", O_RDONLY))) {
85      int line = 0;
86
87      len = fdlength(fd);
88      conf = xmmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
89
90      // Loop through lines in mmaped file
91      for (pos = conf; pos-conf<len;) {
92        int field;
93        char *end2;
94
95        line++;
96        // find end of this line
97        for(end = pos; end-conf<len && *end!='\n'; end++);
98
99        // Three fields: regex, uid:gid, mode
100        for (field = 3; field; field--) {
101          // Skip whitespace
102          while (pos<end && isspace(*pos)) pos++;
103          if (pos==end || *pos=='#') break;
104          for (end2 = pos;
105            end2<end && !isspace(*end2) && *end2!='#'; end2++);
106          switch(field) {
107            // Regex to match this device
108            case 3:
109            {
110              char *regex = strndup(pos, end2-pos);
111              regex_t match;
112              regmatch_t off;
113              int result;
114
115              // Is this it?
116              xregcomp(&match, regex, REG_EXTENDED);
117              result=regexec(&match, device_name, 1, &off, 0);
118              regfree(&match);
119              free(regex);
120
121              // If not this device, skip rest of line
122              if (result || off.rm_so
123                || off.rm_eo!=strlen(device_name))
124                  goto end_line;
125
126              break;
127            }
128            // uid:gid
129            case 2:
130            {
131              char *s2;
132
133              // Find :
134              for(s = pos; s<end2 && *s!=':'; s++);
135              if (s==end2) goto end_line;
136
137              // Parse UID
138              uid = strtoul(pos,&s2,10);
139              if (s!=s2) {
140                struct passwd *pass;
141                char *str = strndup(pos, s-pos);
142                pass = getpwnam(str);
143                free(str);
144                if (!pass) goto end_line;
145                uid = pass->pw_uid;
146              }
147              s++;
148              // parse GID
149              gid = strtoul(s,&s2,10);
150              if (end2!=s2) {
151                struct group *grp;
152                char *str = strndup(s, end2-s);
153                grp = getgrnam(str);
154                free(str);
155                if (!grp) goto end_line;
156                gid = grp->gr_gid;
157              }
158              break;
159            }
160            // mode
161            case 1:
162            {
163              mode = strtoul(pos, &pos, 8);
164              if (pos!=end2) goto end_line;
165              goto found_device;
166            }
167          }
168          pos=end2;
169        }
170end_line:
171        // Did everything parse happily?
172        if (field && field!=3) error_exit("Bad line %d", line);
173
174        // Next line
175        pos = ++end;
176      }
177found_device:
178      munmap(conf, len);
179    }
180    close(fd);
181  }
182
183  sprintf(toybuf, "/dev/%s", device_name);
184
185  if ((temp=getenv("ACTION")) && !strcmp(temp, "remove")) {
186    unlink(toybuf);
187    return;
188  }
189
190  if (strchr(device_name, '/'))
191    mkpathat(AT_FDCWD, toybuf, 0, 2);
192  if (mknod(toybuf, mode | type, dev_makedev(major, minor)) && errno != EEXIST)
193    perror_exit("mknod %s failed", toybuf);
194
195
196  if (type == S_IFBLK) close(open(toybuf, O_RDONLY)); // scan for partitions
197
198  if (CFG_MDEV_CONF) mode=chown(toybuf, uid, gid);
199}
200
201static int callback(struct dirtree *node)
202{
203  // Entries in /sys/class/block aren't char devices, so skip 'em.  (We'll
204  // get block devices out of /sys/block.)
205  if(!strcmp(node->name, "block")) return 0;
206
207  // Does this directory have a "dev" entry in it?
208  // This is path based because the hotplug callbacks are
209  if (S_ISDIR(node->st.st_mode) || S_ISLNK(node->st.st_mode)) {
210    int len=4;
211    char *dev = dirtree_path(node, &len);
212    strcpy(dev+len, "/dev");
213    if (!access(dev, R_OK)) make_device(dev);
214    free(dev);
215  }
216
217  // Circa 2.6.25 the entries more than 2 deep are all either redundant
218  // (mouse#, event#) or unnamed (every usb_* entry is called "device").
219
220  return (node->parent && node->parent->parent) ? 0 : DIRTREE_RECURSE;
221}
222
223void mdev_main(void)
224{
225  // Handle -s
226
227  if (toys.optflags) {
228    dirtree_read("/sys/class", callback);
229    if (!access("/sys/block", R_OK)) dirtree_read("/sys/block", callback);
230  } else { // hotplug support
231    make_device(NULL);
232  }
233}
234