aboutsummaryrefslogtreecommitdiff
path: root/toys/mdev.c
blob: e979ca13e34322ea861471fefec8a3f3da79c478 (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
/* vi:set ts=4:
 *
 * mdev - Mini udev for busybox
 *
 * Copyright 2005 Rob Landley <rob@landley.net>
 * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
 */

#include "toys.h"
#include "lib/xregcomp.h"

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

	// Try to read major/minor string

	temp = path+strlen(path);
	strcpy(temp, "/dev");
	fd = open(path, O_RDONLY);
	*temp=0;
	temp++;
	len = read(fd, temp, 64);
	close(fd);
	if (len<1) return;
	temp[len] = 0;

	// Determine device name, type, major and minor

	device_name = strrchr(path, '/') + 1;
	type = path[5]=='c' ? S_IFCHR : S_IFBLK;
	major = minor = 0;
	sscanf(temp, "%u:%u", &major, &minor);

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

	if (CFG_MDEV_CONF) {
		char *conf, *pos, *end;

		// mmap the config file
		if (-1!=(fd = open("/etc/mdev.conf", O_RDONLY))) {
			len = lseek(fd, 0, SEEK_END);
			conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
			if (conf) {
				int line = 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++);

					// Three fields: regex, uid:gid, mode
					for (field = 3; 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 3:
							{
								char *regex = strndupa(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);

								// 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 2:
							{
								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;
									pass = getpwnam(strndupa(pos, s-pos));
									if (!pass) goto end_line;
									uid = pass->pw_uid;
								}
								s++;
								// parse GID
								gid = strtoul(s,&s2,10);
								if (end2!=s2) {
									struct group *grp;
									grp = getgrnam(strndupa(s, end2-s));
									if (!grp) goto end_line;
									gid = grp->gr_gid;
								}
								break;
							}
							// mode
							case 1:
							{
								mode = strtoul(pos, &pos, 8);
								if (pos!=end2) goto end_line;
								goto found_device;
							}
						}
						pos=end2;
					}
end_line:
					// Did everything parse happily?
					if (field && field!=3) error_exit("Bad line %d", line);

					// Next line
					pos = ++end;
				}
found_device:
				munmap(conf, len);
			}
			close(fd);
		}
	}

	sprintf(temp, "/dev/%s", device_name);
	umask(0);
	if (mknod(temp, mode | type, makedev(major, minor)) && errno != EEXIST)
		perror_exit("mknod %s failed", temp);

	if (CFG_MDEV_CONF) chown(temp, uid, gid);
}

// Recursive search of /sys/block or /sys/class.  path must be a writeable
// buffer of size PATH_MAX containing the directory string to start at.

static void find_dev(char *path)
{
	DIR *dir;
	int len=strlen(path);

	if (!(dir = opendir(path)))
		perror_exit("No %s",path);

	for (;;) {
		struct dirent *entry = readdir(dir);

		if (!entry) break;

		// Skip "." and ".." (also skips hidden files, which is ok)

		if (entry->d_name[0]=='.') continue;

		if (entry->d_type == DT_DIR) {
			snprintf(path+len, sizeof(toybuf)-len, "/%s", entry->d_name);
			find_dev(path);
			path[len] = 0;
		}

		// If there's a dev entry, mknod it

		if (strcmp(entry->d_name, "dev")) make_device(path);
	}

	closedir(dir);
}

void mdev_main(int argc, char *argv[])
{
	if (toys.optflags) {
		strcpy(toybuf, "/sys/block");
		find_dev(toybuf);
		strcpy(toybuf, "/sys/class");
		find_dev(toybuf);
		return;
	}

	// hotplug support goes here
}