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 #define MAX_SYSFS_DEPTH 3 /* prevent infinite loops in /sys symlinks */
  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         const 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 = bb_basename(path);
  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 = xstrndup(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                                         free(regex);
 103
 104                                         /* If not this device, skip rest of line */
 105                                         if (result || off.rm_so
 106                                                         || off.rm_eo != strlen(device_name))
 107                                                 break;
 108                                 }
 109                                 if (field == 1) {
 110                                         /* uid:gid */
 111
 112                                         char *s, *s2;
 113
 114                                         /* Find : */
 115                                         for (s=pos; s<end2 && *s!=':'; s++)
 116                                                 ;
 117                                         if (s == end2) break;
 118
 119                                         /* Parse UID */
 120                                         uid = strtoul(pos, &s2, 10);
 121                                         if (s != s2) {
 122                                                 struct passwd *pass;
 123                                                 char *_unam = xstrndup(pos, s-pos);
 124                                                 pass = getpwnam(_unam);
 125                                                 free(_unam);
 126                                                 if (!pass) break;
 127                                                 uid = pass->pw_uid;
 128                                         }
 129                                         s++;
 130                                         /* parse GID */
 131                                         gid = strtoul(s, &s2, 10);
 132                                         if (end2 != s2) {
 133                                                 struct group *grp;
 134                                                 char *_grnam = xstrndup(s, end2-s);
 135                                                 grp = getgrnam(_grnam);
 136                                                 free(_grnam);
 137                                                 if (!grp) break;
 138                                                 gid = grp->gr_gid;
 139                                         }
 140                                 }
 141                                 if (field == 2) {
 142                                         /* mode */
 143
 144                                         mode = strtoul(pos, &pos, 8);
 145                                         if (pos != end2) break;
 146                                 }
 147                                 if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
 148                                         // Command to run
 149                                         const char *s = "@$*";
 150                                         const char *s2;
 151                                         s2 = strchr(s, *pos++);
 152                                         if (!s2) {
 153                                                 // Force error
 154                                                 field = 1;
 155                                                 break;
 156                                         }
 157                                         if ((s2-s+1) & (1<<delete))
 158                                                 command = xstrndup(pos, end-pos);
 159                                 }
 160
 161                                 pos = end2;
 162                         }
 163
 164                         /* Did everything parse happily? */
 165
 166                         if (field > 2) break;
 167                         if (field) bb_error_msg_and_die("bad line %d",line);
 168
 169                         /* Next line */
 170                         pos = ++end;
 171                 }
 172                 munmap(conf, len);
 173  end_parse:     /* nothing */ ;
 174         }
 175
 176         umask(0);
 177         if (!delete) {
 178                 if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
 179                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 180                         bb_perror_msg_and_die("mknod %s", device_name);
 181
 182                 if (major == root_major && minor == root_minor)
 183                         symlink(device_name, "root");
 184
 185                 if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
 186         }
 187         if (command) {
 188                 /* setenv will leak memory, so use putenv */
 189                 char *s = xasprintf("MDEV=%s", device_name);
 190                 putenv(s);
 191                 if (system(command) == -1)
 192                         bb_perror_msg_and_die("cannot run %s", command);
 193                 s[4] = '\0';
 194                 unsetenv(s);
 195                 free(s);
 196                 free(command);
 197         }
 198         if (delete) unlink(device_name);
 199 }
 200
 201 /* File callback for /sys/ traversal */
 202 static int fileAction(const char *fileName, struct stat *statbuf,
 203                       void *userData, int depth)
 204 {
 205         size_t len = strlen(fileName) - 4;
 206         char *scratch = userData;
 207
 208         if (strcmp(fileName + len, "/dev"))
 209                 return FALSE;
 210
 211         strcpy(scratch, fileName);
 212         scratch[len] = 0;
 213         make_device(scratch, 0);
 214
 215         return TRUE;
 216 }
 217
 218 /* Directory callback for /sys/ traversal */
 219 static int dirAction(const char *fileName, struct stat *statbuf,
 220                       void *userData, int depth)
 221 {
 222         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 223 }
 224
 225 /* For the full gory details, see linux/Documentation/firmware_class/README
 226  *
 227  * Firmware loading works like this:
 228  * - kernel sets FIRMWARE env var
 229  * - userspace checks /lib/firmware/$FIRMWARE
 230  * - userspace waits for /sys/$DEVPATH/loading to appear
 231  * - userspace writes "1" to /sys/$DEVPATH/loading
 232  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 233  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 234  * - kernel loads firmware into device
 235  */
 236 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 237 {
 238         int cnt;
 239         int firmware_fd, loading_fd, data_fd;
 240
 241         /* check for $FIRMWARE from kernel */
 242         /* XXX: dont bother: open(NULL) works same as open("no-such-file")
 243          * if (!firmware)
 244          *      return;
 245          */
 246
 247         /* check for /lib/firmware/$FIRMWARE */
 248         xchdir("/lib/firmware");
 249         firmware_fd = xopen(firmware, O_RDONLY);
 250
 251         /* in case we goto out ... */
 252         data_fd = -1;
 253
 254         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 255         xchdir(sysfs_path);
 256         for (cnt = 0; cnt < 30; ++cnt) {
 257                 loading_fd = open("loading", O_WRONLY);
 258                 if (loading_fd == -1)
 259                         sleep(1);
 260                 else
 261                         break;
 262         }
 263         if (loading_fd == -1)
 264                 goto out;
 265
 266         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 267         if (write(loading_fd, "1", 1) != 1)
 268                 goto out;
 269
 270         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 271         data_fd = open("data", O_WRONLY);
 272         if (data_fd == -1)
 273                 goto out;
 274         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 275
 276         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 277         if (cnt > 0)
 278                 write(loading_fd, "0", 1);
 279         else
 280                 write(loading_fd, "-1", 2);
 281
 282  out:
 283         if (ENABLE_FEATURE_CLEAN_UP) {
 284                 close(firmware_fd);
 285                 close(loading_fd);
 286                 close(data_fd);
 287         }
 288 }
 289
 290 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 291 int mdev_main(int argc, char **argv)
 292 {
 293         char *action;
 294         char *env_path;
 295         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 296
 297         xchdir("/dev");
 298
 299         /* Scan */
 300
 301         if (argc == 2 && !strcmp(argv[1],"-s")) {
 302                 struct stat st;
 303
 304                 xstat("/", &st);
 305                 root_major = major(st.st_dev);
 306                 root_minor = minor(st.st_dev);
 307
 308                 recursive_action("/sys/block",
 309                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 310                         fileAction, dirAction, temp, 0);
 311
 312                 recursive_action("/sys/class",
 313                         ACTION_RECURSE | ACTION_FOLLOWLINKS,
 314                         fileAction, dirAction, temp, 0);
 315
 316         /* Hotplug */
 317
 318         } else {
 319                 action = getenv("ACTION");
 320                 env_path = getenv("DEVPATH");
 321                 if (!action || !env_path)
 322                         bb_show_usage();
 323
 324                 sprintf(temp, "/sys%s", env_path);
 325                 if (!strcmp(action, "remove"))
 326                         make_device(temp, 1);
 327                 else if (!strcmp(action, "add")) {
 328                         make_device(temp, 0);
 329
 330                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE)
 331                                 load_firmware(getenv("FIRMWARE"), temp);
 332                 }
 333         }
 334
 335         if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
 336         return 0;
 337 }