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
6 USE_MDEV(NEWTOY(mdev, "s", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_UMASK))
7
8 config 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
18 config 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 (sd[a-z]) root:disk 660 =usb_storage
26
27 Each line must contain three whitespace separated fields. The first
28 field is a regular expression matching one or more device names,
29 the second and third fields are uid:gid and file permissions for
30 matching devices. Fourth field is optional. It could be used to change
31 device name (prefix '='), path (prefix '=' and postfix '/') or create a
32 symlink (prefix '>').
33 */
34
35 #include "toys.h"
36 #include <stdbool.h>
37
38 // mknod in /dev based on a path like "/sys/block/hda/hda1"
make_device(char * path)39 static void make_device(char *path)
40 {
41 char *device_name = 0, *custom_name = 0, *s, *temp;
42 bool create_symlink = false;
43 int major = 0, minor = 0, type, len, fd, mode = 0660;
44 uid_t uid = 0;
45 gid_t gid = 0;
46
47 if (path) {
48
49 // Try to read major/minor string, returning if we can't
50 temp = strrchr(path, '/');
51 fd = open(path, O_RDONLY);
52 *temp = 0;
53 len = read(fd, toybuf, 64);
54 close(fd);
55 if (len<1) return;
56 toybuf[len] = 0;
57
58 // Determine device type, major and minor
59
60 type = path[5]=='c' ? S_IFCHR : S_IFBLK;
61 sscanf(toybuf, "%u:%u", &major, &minor);
62 } else {
63 // if (!path), do hotplug
64
65 if (!(temp = getenv("MODALIAS"))) xrun((char *[]){"modprobe", temp, 0});
66 if (!(temp = getenv("SUBSYSTEM"))) return;
67 type = strcmp(temp, "block") ? S_IFCHR : S_IFBLK;
68 if (!(temp = getenv("MAJOR"))) return;
69 sscanf(temp, "%u", &major);
70 if (!(temp = getenv("MINOR"))) return;
71 sscanf(temp, "%u", &minor);
72 if (!(path = getenv("DEVPATH"))) return;
73 device_name = getenv("DEVNAME");
74 }
75 if (!device_name)
76 device_name = strrchr(path, '/') + 1;
77
78 // as in linux/drivers/base/core.c, device_get_devnode()
79 while ((temp = strchr(device_name, '!'))) {
80 *temp = '/';
81 }
82
83 // If we have a config file, look up permissions for this device
84
85 if (CFG_MDEV_CONF) {
86 char *conf, *pos, *end;
87 bool optional_field_valid = false;
88
89 // mmap the config file
90 if (-1!=(fd = open("/etc/mdev.conf", O_RDONLY))) {
91 int line = 0;
92
93 len = fdlength(fd);
94 conf = xmmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
95
96 // Loop through lines in mmaped file
97 for (pos = conf; pos-conf<len;) {
98 int field;
99 char *end2;
100
101 line++;
102 // find end of this line
103 for(end = pos; end-conf<len && *end!='\n'; end++);
104
105 // Four fields (last is optional): regex, uid:gid, mode [, name|path ]
106 // For example: (sd[a-z])1 root:disk 660 =usb_storage_p1
107 for (field = 4; field; field--) {
108 // Skip whitespace
109 while (pos<end && isspace(*pos)) pos++;
110 if (pos==end || *pos=='#') break;
111 for (end2 = pos;
112 end2<end && !isspace(*end2) && *end2!='#'; end2++);
113 switch(field) {
114 // Regex to match this device
115 case 4:
116 {
117 char *regex = strndup(pos, end2-pos);
118 regex_t match;
119 regmatch_t off;
120 int result;
121
122 // Is this it?
123 xregcomp(&match, regex, REG_EXTENDED);
124 result=regexec(&match, device_name, 1, &off, 0);
125 regfree(&match);
126 free(regex);
127
128 // If not this device, skip rest of line
129 if (result || off.rm_so
130 || off.rm_eo!=strlen(device_name))
131 goto end_line;
132
133 break;
134 }
135 // uid:gid
136 case 3:
137 {
138 char *s2;
139
140 // Find :
141 for(s = pos; s<end2 && *s!=':'; s++);
142 if (s==end2) goto end_line;
143
144 // Parse UID
145 uid = strtoul(pos,&s2,10);
146 if (s!=s2) {
147 struct passwd *pass;
148 char *str = strndup(pos, s-pos);
149 pass = getpwnam(str);
150 free(str);
151 if (!pass) goto end_line;
152 uid = pass->pw_uid;
153 }
154 s++;
155 // parse GID
156 gid = strtoul(s,&s2,10);
157 if (end2!=s2) {
158 struct group *grp;
159 char *str = strndup(s, end2-s);
160 grp = getgrnam(str);
161 free(str);
162 if (!grp) goto end_line;
163 gid = grp->gr_gid;
164 }
165 break;
166 }
167 // mode
168 case 2:
169 {
170 char *beg_pos = pos;
171 mode = strtoul(pos, &pos, 8);
172 if (pos == beg_pos) {
173 // The line is bad because mode setting could not be
174 // converted to numeric value.
175 goto end_line;
176 }
177 break;
178 }
179 // Try to look for name or path (optional field)
180 case 1:
181 {
182 if(pos < end2){
183 //char *name = strndup(pos, end2-pos);
184 char *name = malloc(end2-pos+1);
185 if(name){
186 strncpy(name, pos, end2-pos+1);
187 name[end2-pos] = '\0';
188 switch(name[0]){
189 case '>':
190 create_symlink = true;
191 case '=':
192 custom_name = strdup(&name[1]);
193 break;
194 case '!':
195 device_name = NULL;
196 break;
197 default:
198 free(name);
199 goto end_line;
200 }
201 free(name);
202 optional_field_valid = true;
203 }
204 }
205 goto found_device;
206 }
207 }
208 pos=end2;
209 }
210 end_line:
211 // Did everything parse happily?
212 // Note: Last field is optional.
213 if ((field>1 || (field==1 && !optional_field_valid)) && field!=4)
214 error_exit("Bad line %d", line);
215 // Next line
216 pos = ++end;
217 }
218 found_device:
219 munmap(conf, len);
220 }
221 close(fd);
222 }
223
224 if(device_name) {
225 if(custom_name) {
226 sprintf(toybuf, "/dev/%s", custom_name);
227 if(custom_name[strlen(custom_name) - 1] == '/') {
228 DIR *dir;
229 dir = opendir(toybuf);
230 if(dir) closedir(dir);
231 else mkdir(toybuf, 0755);
232 }
233 }
234 else
235 sprintf(toybuf, "/dev/%s", device_name);
236
237 if ((temp=getenv("ACTION")) && !strcmp(temp, "remove")) {
238 unlink(toybuf);
239 return;
240 }
241
242 if (strchr(device_name, '/')) mkpath(toybuf);
243 if (mknod(toybuf, mode | type, dev_makedev(major, minor)) &&
244 errno != EEXIST)
245 perror_exit("mknod %s failed", toybuf);
246 if(create_symlink){
247 char *symlink_name = malloc(sizeof("/dev/") + strlen(device_name) + 1);
248 if(symlink_name == NULL)
249 perror_exit("malloc failed while creating symlink to %s", toybuf);
250 sprintf(symlink_name, "/dev/%s", device_name);
251 if(symlink(toybuf, symlink_name)){
252 free(symlink_name);
253 perror_exit("symlink creation failed for %s", toybuf);
254 }
255 free(symlink_name);
256 }
257
258 if (type == S_IFBLK) close(open(toybuf, O_RDONLY)); // scan for partitions
259
260 if (CFG_MDEV_CONF) mode=chown(toybuf, uid, gid);
261 }
262 }
263
callback(struct dirtree * node)264 static int callback(struct dirtree *node)
265 {
266 // Entries in /sys/class/block aren't char devices, so skip 'em. (We'll
267 // get block devices out of /sys/block.)
268 if(!strcmp(node->name, "block")) return 0;
269
270 // Does this directory have a "dev" entry in it?
271 // This is path based because the hotplug callbacks are
272 if (S_ISDIR(node->st.st_mode) || S_ISLNK(node->st.st_mode)) {
273 int len=4;
274 char *dev = dirtree_path(node, &len);
275 strcpy(dev+len, "/dev");
276 if (!access(dev, R_OK)) make_device(dev);
277 free(dev);
278 }
279
280 // Circa 2.6.25 the entries more than 2 deep are all either redundant
281 // (mouse#, event#) or unnamed (every usb_* entry is called "device").
282
283 if (node->parent && node->parent->parent) return 0;
284 return DIRTREE_RECURSE|DIRTREE_SYMFOLLOW;
285 }
286
mdev_main(void)287 void mdev_main(void)
288 {
289 // Handle -s
290
291 if (toys.optflags) {
292 dirtree_read("/sys/class", callback);
293 if (!access("/sys/block", R_OK)) dirtree_read("/sys/block", callback);
294 } else { // hotplug support
295 make_device(NULL);
296 }
297 }
298