util-linux/mdev.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  *
   4  * mdev - Mini udev for busybox
   5  *
   6  * Copyright 2005 Rob Landley <rob@landley.net>
   7  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   8  *
   9  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  10  */
  11
  12 #include "libbb.h"
  13 #include "xregex.h"
  14
  15 struct globals {
  16         int root_major, root_minor;
  17 };
  18 #define G (*(struct globals*)&bb_common_bufsiz1)
  19 #define root_major (G.root_major)
  20 #define root_minor (G.root_minor)
  21
  22 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  23 static void make_device(char *path, int delete)
  24 {
  25         char *device_name;
  26         int major, minor, type, len;
  27         int mode = 0660;
  28         uid_t uid = 0;
  29         gid_t gid = 0;
  30         char *temp = path + strlen(path);
  31         char *command = NULL;
  32
  33         /* Try to read major/minor string.  Note that the kernel puts \n after
  34          * the data, so we don't need to worry about null terminating the string
  35          * because sscanf() will stop at the first nondigit, which \n is.  We
  36          * also depend on path having writeable space after it. */
  37
  38         if (!delete) {
  39                 strcat(path, "/dev");
  40                 len = open_read_close(path, temp + 1, 64);
  41                 *temp++ = 0;
  42                 if (len < 1) return;
  43         }
  44
  45         /* Determine device name, type, major and minor */
  46
  47         device_name = strrchr(path, '/') + 1;
  48         type = path[5]=='c' ? S_IFCHR : S_IFBLK;
  49
  50         /* If we have a config file, look up permissions for this device */
  51
  52         if (ENABLE_FEATURE_MDEV_CONF) {
  53                 char *conf, *pos, *end;
  54                 int line, fd;
  55
  56                 /* mmap the config file */
  57                 fd = open("/etc/mdev.conf", O_RDONLY);
  58                 if (fd < 0)
  59                         goto end_parse;
  60                 len = xlseek(fd, 0, SEEK_END);
  61                 conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  62                 close(fd);
  63                 if (!conf)
  64                         goto end_parse;
  65
  66                 line = 0;
  67                 /* Loop through lines in mmaped file*/
  68                 for (pos=conf; pos-conf<len;) {
  69                         int field;
  70                         char *end2;
  71
  72                         line++;
  73                         /* find end of this line */
  74                         for (end=pos; end-conf<len && *end!='\n'; end++)
  75                                 ;
  76
  77                         /* Three fields: regex, uid:gid, mode */
  78                         for (field=0; field < (3 + ENABLE_FEATURE_MDEV_EXEC);
  79                                         field++)
  80                         {
  81                                 /* Skip whitespace */
  82                                 while (pos<end && isspace(*pos)) pos++;
  83                                 if (pos==end || *pos=='#') break;
  84                                 for (end2=pos;
  85                                         end2<end && !isspace(*end2) && *end2!='#'; end2++)
  86                                         ;
  87
  88                                 if (field == 0) {
  89                                         /* Regex to match this device */
  90
  91                                         char *regex = strndupa(pos, end2-pos);
  92                                         regex_t match;
  93                                         regmatch_t off;
  94                                         int result;
  95
  96                                         /* Is this it? */
  97                                         xregcomp(&match,regex, REG_EXTENDED);
  98                                         result = regexec(&match, device_name, 1, &off, 0);
  99                                         regfree(&match);
 100
 101                                         /* If not this device, skip rest of line */
 102                                         if (result || off.rm_so
 103                                                         || off.rm_eo != strlen(device_name))
 104                                                 break;
 105                                 }
 106                                 if (field == 1) {
 107                                         /* uid:gid */
 108
 109                                         char *s, *s2;
 110
 111                                         /* Find : */
 112                                         for (s=pos; s<end2 && *s!=':'; s++)
 113                                                 ;
 114                                         if (s == end2) break;
 115
 116                                         /* Parse UID */
 117                                         uid = strtoul(pos, &s2, 10);
 118                                         if (s != s2) {
 119                                                 struct passwd *pass;
 120                                                 pass = getpwnam(strndupa(pos, s-pos));
 121                                                 if (!pass) break;
 122                                                 uid = pass->pw_uid;
 123                                         }
 124                                         s++;
 125                                         /* parse GID */
 126                                         gid = strtoul(s, &s2, 10);
 127                                         if (end2 != s2) {
 128                                                 struct group *grp;
 129                                                 grp = getgrnam(strndupa(s, end2-s));
 130                                                 if (!grp) break;
 131                                                 gid = grp->gr_gid;
 132                                         }
 133                                 }
 134                                 if (field == 2) {
 135                                         /* mode */
 136
 137                                         mode = strtoul(pos, &pos, 8);
 138                                         if (pos != end2) break;
 139                                 }
 140                                 if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
 141                                         // Command to run
 142                                         const char *s = "@$*";
 143                                         const char *s2;
 144                                         s2 = strchr(s, *pos++);
 145                                         if (!s2) {
 146                                                 // Force error
 147                                                 field = 1;
 148                                                 break;
 149                                         }
 150                                         if ((s2-s+1) & (1<<delete))
 151                                                 command = xstrndup(pos, end-pos);
 152                                 }
 153
 154                                 pos = end2;
 155                         }
 156
 157                         /* Did everything parse happily? */
 158
 159                         if (field > 2) break;
 160                         if (field) bb_error_msg_and_die("bad line %d",line);
 161
 162                         /* Next line */
 163                         pos = ++end;
 164                 }
 165                 munmap(conf, len);
 166  end_parse:     /* nothing */ ;
 167         }
 168
 169         umask(0);
 170         if (!delete) {
 171                 if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
 172                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 173                         bb_perror_msg_and_die("mknod %s", device_name);
 174
 175                 if (major == root_major && minor == root_minor)
 176                         symlink(device_name, "root");
 177
 178                 if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
 179         }
 180         if (command) {
 181                 /* setenv will leak memory, so use putenv */
 182                 char *s = xasprintf("MDEV=%s", device_name);
 183                 putenv(s);
 184                 if (system(command) == -1)
 185                         bb_perror_msg_and_die("cannot run %s", command);
 186                 s[4] = '\0';
 187                 unsetenv(s);
 188                 free(s);
 189                 free(command);
 190         }
 191         if (delete) unlink(device_name);
 192 }
 193
 194 /* Recursive search of /sys/block or /sys/class.  path must be a writeable
 195  * buffer of size PATH_MAX containing the directory string to start at. */
 196
 197 static void find_dev(char *path)
 198 {
 199         DIR *dir;
 200         size_t len = strlen(path);
 201         struct dirent *entry;
 202
 203         dir = opendir(path);
 204         if (dir == NULL)
 205                 return;
 206
 207         while ((entry = readdir(dir)) != NULL) {
 208                 struct stat st;
 209
 210                 /* Skip "." and ".." (also skips hidden files, which is ok) */
 211
 212                 if (entry->d_name[0] == '.')
 213                         continue;
 214
 215                 // uClibc doesn't fill out entry->d_type reliably. so we use lstat().
 216
 217                 snprintf(path+len, PATH_MAX-len, "/%s", entry->d_name);
 218                 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) find_dev(path);
 219                 path[len] = 0;
 220
 221                 /* If there's a dev entry, mknod it */
 222
 223                 if (!strcmp(entry->d_name, "dev")) make_device(path, 0);
 224         }
 225
 226         closedir(dir);
 227 }
 228
 229 int mdev_main(int argc, char **argv);
 230 int mdev_main(int argc, char **argv)
 231 {
 232         char *action;
 233         char *env_path;
 234         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 235
 236         xchdir("/dev");
 237
 238         /* Scan */
 239
 240         if (argc == 2 && !strcmp(argv[1],"-s")) {
 241                 struct stat st;
 242
 243                 xstat("/", &st);
 244                 root_major = major(st.st_dev);
 245                 root_minor = minor(st.st_dev);
 246                 strcpy(temp,"/sys/block");
 247                 find_dev(temp);
 248                 strcpy(temp,"/sys/class");
 249                 find_dev(temp);
 250
 251         /* Hotplug */
 252
 253         } else {
 254                 action = getenv("ACTION");
 255                 env_path = getenv("DEVPATH");
 256                 if (!action || !env_path)
 257                         bb_show_usage();
 258
 259                 sprintf(temp, "/sys%s", env_path);
 260                 if (!strcmp(action, "add")) make_device(temp,0);
 261                 else if (!strcmp(action, "remove")) make_device(temp,1);
 262         }
 263
 264         if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
 265         return 0;
 266 }