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