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 GPLv2 or later, 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         strcat(path, "/dev");
  41         fd = open(path, O_RDONLY);
  42         len = read(fd, temp + 1, 64);
  43         *temp++ = 0;
  44         close(fd);
  45         if (len < 1) return;
  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         if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
  52
  53         /* If we have a config file, look up permissions for this device */
  54
  55         if (ENABLE_FEATURE_MDEV_CONF) {
  56                 char *conf, *pos, *end;
  57
  58                 /* mmap the config file */
  59                 if (-1 != (fd=open("/etc/mdev.conf",O_RDONLY))) {
  60                         len = lseek(fd, 0, SEEK_END);
  61                         conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  62                         if (conf) {
  63                                 int line = 0;
  64
  65                                 /* Loop through lines in mmaped file*/
  66                                 for (pos=conf; pos-conf<len;) {
  67                                         int field;
  68                                         char *end2;
  69
  70                                         line++;
  71                                         /* find end of this line */
  72                                         for(end=pos; end-conf<len && *end!='\n'; end++)
  73                                                 ;
  74
  75                                         /* Three fields: regex, uid:gid, mode */
  76                                         for (field=0; field < (3 + ENABLE_FEATURE_MDEV_EXEC);
  77                                                         field++)
  78                                         {
  79                                                 /* Skip whitespace */
  80                                                 while (pos<end && isspace(*pos)) pos++;
  81                                                 if (pos==end || *pos=='#') break;
  82                                                 for (end2=pos;
  83                                                         end2<end && !isspace(*end2) && *end2!='#'; end2++)
  84                                                         ;
  85
  86                                                 if (!field) {
  87                                                         /* Regex to match this device */
  88
  89                                                         char *regex = strndupa(pos, end2-pos);
  90                                                         regex_t match;
  91                                                         regmatch_t off;
  92                                                         int result;
  93
  94                                                         /* Is this it? */
  95                                                         xregcomp(&match,regex, REG_EXTENDED);
  96                                                         result = regexec(&match, device_name, 1, &off, 0);
  97                                                         regfree(&match);
  98
  99                                                         /* If not this device, skip rest of line */
 100                                                         if (result || off.rm_so
 101                                                                         || off.rm_eo != strlen(device_name))
 102                                                                 break;
 103
 104                                                 } else if (field == 1) {
 105                                                         /* uid:gid */
 106
 107                                                         char *s, *s2;
 108
 109                                                         /* Find : */
 110                                                         for(s=pos; s<end2 && *s!=':'; s++)
 111                                                                 ;
 112                                                         if (s == end2) break;
 113
 114                                                         /* Parse UID */
 115                                                         uid = strtoul(pos,&s2,10);
 116                                                         if (s != s2) {
 117                                                                 struct passwd *pass;
 118                                                                 pass = getpwnam(strndupa(pos, s-pos));
 119                                                                 if (!pass) break;
 120                                                                 uid = pass->pw_uid;
 121                                                         }
 122                                                         s++;
 123                                                         /* parse GID */
 124                                                         gid = strtoul(s, &s2, 10);
 125                                                         if (end2 != s2) {
 126                                                                 struct group *grp;
 127                                                                 grp = getgrnam(strndupa(s, end2-s));
 128                                                                 if (!grp) break;
 129                                                                 gid = grp->gr_gid;
 130                                                         }
 131                                                 } else if (field == 2) {
 132                                                         /* mode */
 133
 134                                                         mode = strtoul(pos, &pos, 8);
 135                                                         if (pos != end2) break;
 136                                                 } else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
 137                                                         // Command to run
 138                                                         char *s = "@$*", *s2;
 139                                                         if (!(s2 = strchr(s, *pos++))) {
 140                                                                 // Force error
 141                                                                 field = 1;
 142                                                                 break;
 143                                                         }
 144                                                         if ((s2-s+1) & (1<<delete))
 145                                                                 command = xstrndup(pos, end-pos);
 146                                                 }
 147
 148                                                 pos = end2;
 149                                         }
 150
 151                                         /* Did everything parse happily? */
 152
 153                                         if (field > 2) break;
 154                                         if (field) bb_error_msg_and_die("Bad line %d",line);
 155
 156                                         /* Next line */
 157                                         pos = ++end;
 158                                 }
 159                                 munmap(conf, len);
 160                         }
 161                         close(fd);
 162                 }
 163         }
 164
 165         umask(0);
 166         if (!delete) {
 167                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 168                         bb_perror_msg_and_die("mknod %s failed", device_name);
 169
 170                 if (major == bbg.root_major && minor == bbg.root_minor)
 171                         symlink(device_name, "root");
 172
 173                 if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
 174         }
 175         if (command) {
 176                 int rc;
 177                 char *s;
 178
 179                 s=xasprintf("MDEV=%s",device_name);
 180                 putenv(s);
 181                 rc = system(command);
 182                 s[4]=0;
 183                 putenv(s);
 184                 free(s);
 185                 free(command);
 186                 if (rc == -1) bb_perror_msg_and_die("Couldn't run %s", command);
 187         }
 188         if (delete) unlink(device_name);
 189 }
 190
 191 /* Recursive search of /sys/block or /sys/class.  path must be a writeable
 192  * buffer of size PATH_MAX containing the directory string to start at. */
 193
 194 static void find_dev(char *path)
 195 {
 196         DIR *dir;
 197         size_t len = strlen(path);
 198         struct dirent *entry;
 199
 200         if ((dir = opendir(path)) == NULL)
 201                 return;
 202
 203         while ((entry = readdir(dir)) != NULL) {
 204                 struct stat st;
 205
 206                 /* Skip "." and ".." (also skips hidden files, which is ok) */
 207
 208                 if (entry->d_name[0] == '.')
 209                         continue;
 210
 211                 // uClibc doesn't fill out entry->d_type reliably. so we use lstat().
 212
 213                 snprintf(path+len, PATH_MAX-len, "/%s", entry->d_name);
 214                 if (!lstat(path, &st) && S_ISDIR(st.st_mode)) find_dev(path);
 215                 path[len] = 0;
 216
 217                 /* If there's a dev entry, mknod it */
 218
 219                 if (!strcmp(entry->d_name, "dev")) make_device(path, 0);
 220         }
 221
 222         closedir(dir);
 223 }
 224
 225 int mdev_main(int argc, char *argv[])
 226 {
 227         char *action;
 228         char *env_path;
 229         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 230
 231         xchdir(DEV_PATH);
 232
 233         /* Scan */
 234
 235         if (argc == 2 && !strcmp(argv[1],"-s")) {
 236                 struct stat st;
 237
 238                 stat("/", &st);  // If this fails, we have bigger problems.
 239                 bbg.root_major=major(st.st_dev);
 240                 bbg.root_minor=minor(st.st_dev);
 241                 strcpy(temp,"/sys/block");
 242                 find_dev(temp);
 243                 strcpy(temp,"/sys/class");
 244                 find_dev(temp);
 245
 246         /* Hotplug */
 247
 248         } else {
 249                 action = getenv("ACTION");
 250                 env_path = getenv("DEVPATH");
 251             if (!action || !env_path)
 252                         bb_show_usage();
 253
 254                 sprintf(temp, "/sys%s", env_path);
 255                 if (!strcmp(action, "add")) make_device(temp,0);
 256                 else if (!strcmp(action, "remove")) make_device(temp,1);
 257         }
 258
 259         if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
 260         return 0;
 261 }