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 "busybox.h"
  13 #include "xregex.h"
  14
  15 #define DEV_PATH        "/dev"
  16
  17 struct mdev_globals
  18 {
  19         int root_major, root_minor;
  20 } mdev_globals;
  21
  22 #define bbg mdev_globals
  23
  24 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  25 static void make_device(char *path, int delete)
  26 {
  27         char *device_name;
  28         int major, minor, type, len;
  29         int mode = 0660;
  30         uid_t uid = 0;
  31         gid_t gid = 0;
  32         char *temp = path + strlen(path);
  33         char *command = NULL;
  34
  35         /* Try to read major/minor string.  Note that the kernel puts \n after
  36          * the data, so we don't need to worry about null terminating the string
  37          * because sscanf() will stop at the first nondigit, which \n is.  We
  38          * also depend on path having writeable space after it. */
  39
  40         if (!delete) {
  41                 strcat(path, "/dev");
  42                 len = open_read_close(path, temp + 1, 64);
  43                 *temp++ = 0;
  44                 if (len < 1) return;
  45         }
  46
  47         /* Determine device name, type, major and minor */
  48
  49         device_name = strrchr(path, '/') + 1;
  50         type = path[5]=='c' ? S_IFCHR : S_IFBLK;
  51
  52         /* If we have a config file, look up permissions for this device */
  53
  54         if (ENABLE_FEATURE_MDEV_CONF) {
  55                 char *conf, *pos, *end;
  56                 int line, fd;
  57
  58                 /* mmap the config file */
  59                 fd = open("/etc/mdev.conf", O_RDONLY);
  60                 if (fd < 0)
  61                         goto end_parse;
  62                 len = xlseek(fd, 0, SEEK_END);
  63                 conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  64                 close(fd);
  65                 if (!conf)
  66                         goto end_parse;
  67
  68                 line = 0;
  69                 /* Loop through lines in mmaped file*/
  70                 for (pos=conf; pos-conf<len;) {
  71                         int field;
  72                         char *end2;
  73
  74                         line++;
  75                         /* find end of this line */
  76                         for(end=pos; end-conf<len && *end!='\n'; end++)
  77                                 ;
  78
  79                         /* Three fields: regex, uid:gid, mode */
  80                         for (field=0; field < (3 + ENABLE_FEATURE_MDEV_EXEC);
  81                                         field++)
  82                         {
  83                                 /* Skip whitespace */
  84                                 while (pos<end && isspace(*pos)) pos++;
  85                                 if (pos==end || *pos=='#') break;
  86                                 for (end2=pos;
  87                                         end2<end && !isspace(*end2) && *end2!='#'; end2++)
  88                                         ;
  89
  90                                 if (field == 0) {
  91                                         /* Regex to match this device */
  92
  93                                         char *regex = strndupa(pos, end2-pos);
  94                                         regex_t match;
  95                                         regmatch_t off;
  96                                         int result;
  97
  98                                         /* Is this it? */
  99                                         xregcomp(&match,regex, REG_EXTENDED);
 100                                         result = regexec(&match, device_name, 1, &off, 0);
 101                                         regfree(&match);
 102
 103                                         /* If not this device, skip rest of line */
 104                                         if (result || off.rm_so
 105                                                         || off.rm_eo != strlen(device_name))
 106                                                 break;
 107                                 }
 108                                 if (field == 1) {
 109                                         /* uid:gid */
 110
 111                                         char *s, *s2;
 112
 113                                         /* Find : */
 114                                         for(s=pos; s<end2 && *s!=':'; s++)
 115                                                 ;
 116                                         if (s == end2) break;
 117
 118                                         /* Parse UID */
 119                                         uid = strtoul(pos, &s2, 10);
 120                                         if (s != s2) {
 121                                                 struct passwd *pass;
 122                                                 pass = getpwnam(strndupa(pos, s-pos));
 123                                                 if (!pass) break;
 124                                                 uid = pass->pw_uid;
 125                                         }
 126                                         s++;
 127                                         /* parse GID */
 128                                         gid = strtoul(s, &s2, 10);
 129                                         if (end2 != s2) {
 130                                                 struct group *grp;
 131                                                 grp = getgrnam(strndupa(s, end2-s));
 132                                                 if (!grp) break;
 133                                                 gid = grp->gr_gid;
 134                                         }
 135                                 }
 136                                 if (field == 2) {
 137                                         /* mode */
 138
 139                                         mode = strtoul(pos, &pos, 8);
 140                                         if (pos != end2) break;
 141                                 }
 142                                 if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
 143                                         // Command to run
 144                                         char *s = "@$*", *s2;
 145                                         s2 = strchr(s, *pos++);
 146                                         if (!s2) {
 147                                                 // Force error
 148                                                 field = 1;
 149                                                 break;
 150                                         }
 151                                         if ((s2-s+1) & (1<<delete))
 152                                                 command = xstrndup(pos, end-pos);
 153                                 }
 154
 155                                 pos = end2;
 156                         }
 157
 158                         /* Did everything parse happily? */
 159
 160                         if (field > 2) break;
 161                         if (field) bb_error_msg_and_die("bad line %d",line);
 162
 163                         /* Next line */
 164                         pos = ++end;
 165                 }
 166                 munmap(conf, len);
 167  end_parse:     /* nothing */ ;
 168         }
 169
 170         umask(0);
 171         if (!delete) {
 172                 if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
 173                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 174                         bb_perror_msg_and_die("mknod %s", device_name);
 175
 176                 if (major == bbg.root_major && minor == bbg.root_minor)
 177                         symlink(device_name, "root");
 178
 179                 if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
 180         }
 181         if (command) {
 182                 int rc;
 183                 char *s;
 184
 185                 s = xasprintf("MDEV=%s", device_name);
 186                 putenv(s);
 187                 rc = system(command);
 188                 s[4] = 0;
 189                 putenv(s);
 190                 free(s);
 191                 free(command);
 192                 if (rc == -1) bb_perror_msg_and_die("cannot run %s", command);
 193         }
 194         if (delete) unlink(device_name);
 195 }
 196
 197 /* Recursive search of /sys/block or /sys/class.  path must be a writeable
 198  * buffer of size PATH_MAX containing the directory string to start at. */
 199
 200 static void find_dev(char *path)
 201 {
 202         DIR *dir;
 203         size_t len = strlen(path);
 204         struct dirent *entry;
 205
 206         dir = opendir(path);
 207         if (dir == NULL)
 208                 return;
 209
 210         while ((entry = readdir(dir)) != NULL) {
 211                 struct stat st;
 212
 213                 /* Skip "." and ".." (also skips hidden files, which is ok) */
 214
 215                 if (entry->d_name[0] == '.')
 216                         continue;
 217
 218                 // uClibc doesn't fill out entry->d_type reliably. so we use lstat().
 219
 220                 snprintf(path+len, PATH_MAX-len, "/%s", entry->d_name);
 221                 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) find_dev(path);
 222                 path[len] = 0;
 223
 224                 /* If there's a dev entry, mknod it */
 225
 226                 if (!strcmp(entry->d_name, "dev")) make_device(path, 0);
 227         }
 228
 229         closedir(dir);
 230 }
 231
 232 int mdev_main(int argc, char *argv[])
 233 {
 234         char *action;
 235         char *env_path;
 236         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 237
 238         xchdir(DEV_PATH);
 239
 240         /* Scan */
 241
 242         if (argc == 2 && !strcmp(argv[1],"-s")) {
 243                 struct stat st;
 244
 245                 xstat("/", &st);
 246                 bbg.root_major = major(st.st_dev);
 247                 bbg.root_minor = minor(st.st_dev);
 248                 strcpy(temp,"/sys/block");
 249                 find_dev(temp);
 250                 strcpy(temp,"/sys/class");
 251                 find_dev(temp);
 252
 253         /* Hotplug */
 254
 255         } else {
 256                 action = getenv("ACTION");
 257                 env_path = getenv("DEVPATH");
 258                 if (!action || !env_path)
 259                         bb_show_usage();
 260
 261                 sprintf(temp, "/sys%s", env_path);
 262                 if (!strcmp(action, "add")) make_device(temp,0);
 263                 else if (!strcmp(action, "remove")) make_device(temp,1);
 264         }
 265
 266         if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
 267         return 0;
 268 }