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)
  45                         return;
  46         }
  47
  48         /* Determine device name, type, major and minor */
  49         device_name = bb_basename(path);
  50         type = (path[5] == 'c' ? S_IFCHR : S_IFBLK);
  51
  52         if (ENABLE_FEATURE_MDEV_CONF) {
  53                 FILE *fp;
  54                 char *line, *vline;
  55                 unsigned lineno = 0;
  56
  57                 /* If we have a config file, look up the user settings */
  58                 fp = fopen_or_warn("/etc/mdev.conf", "r");
  59                 if (!fp)
  60                         goto end_parse;
  61
  62                 while ((vline = line = xmalloc_getline(fp)) != NULL) {
  63                         int field;
  64
  65                         /* A pristine copy for command execution. */
  66                         char *orig_line;
  67                         if (ENABLE_FEATURE_MDEV_EXEC)
  68                                 orig_line = xstrdup(line);
  69
  70                         ++lineno;
  71
  72                         /* Three fields: regex, uid:gid, mode */
  73                         for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_EXEC); ++field) {
  74
  75                                 /* Find a non-empty field */
  76                                 char *val;
  77                                 do {
  78                                         val = strtok(vline, " \t");
  79                                         vline = NULL;
  80                                 } while (val && !*val);
  81                                 if (!val) {
  82                                         if (field)
  83                                                 break;
  84                                         else
  85                                                 goto next_line;
  86                                 }
  87
  88                                 if (field == 0) {
  89
  90                                         /* Regex to match this device */
  91                                         regex_t match;
  92                                         regmatch_t off;
  93                                         int result;
  94
  95                                         /* Is this it? */
  96                                         xregcomp(&match, val, 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 || off.rm_eo != strlen(device_name))
 102                                                 goto next_line;
 103
 104                                 } else if (field == 1) {
 105
 106                                         /* uid:gid device ownership */
 107                                         struct passwd *pass;
 108                                         struct group *grp;
 109
 110                                         char *str_uid = val;
 111                                         char *str_gid = strchr(val, ':');
 112                                         if (str_gid)
 113                                                 *str_gid = '\0', ++str_gid;
 114
 115                                         /* Parse UID */
 116                                         pass = getpwnam(str_uid);
 117                                         if (pass)
 118                                                 uid = pass->pw_uid;
 119                                         else
 120                                                 uid = strtoul(str_uid, NULL, 10);
 121
 122                                         /* parse GID */
 123                                         grp = getgrnam(str_gid);
 124                                         if (grp)
 125                                                 gid = grp->gr_gid;
 126                                         else
 127                                                 gid = strtoul(str_gid, NULL, 10);
 128
 129                                 } else if (field == 2) {
 130
 131                                         /* Mode device permissions */
 132                                         mode = strtoul(val, NULL, 8);
 133
 134                                 } else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
 135
 136                                         /* Optional command to run */
 137                                         const char *s = "@$*";
 138                                         const char *s2 = strchr(s, *val);
 139
 140                                         if (!s2) {
 141                                                 /* Force error */
 142                                                 field = 1;
 143                                                 break;
 144                                         }
 145
 146                                         /* Correlate the position in the "@$*" with the delete
 147                                          * step so that we get the proper behavior.
 148                                          */
 149                                         if ((s2 - s + 1) & (1 << delete))
 150                                                 command = xstrdup(orig_line + (val + 1 - line));
 151                                 }
 152                         }
 153
 154                         /* Did everything parse happily? */
 155                         if (field <= 2)
 156                                 bb_error_msg_and_die("bad line %u", lineno);
 157
 158  next_line:
 159                         free(line);
 160                         if (ENABLE_FEATURE_MDEV_EXEC)
 161                                 free(orig_line);
 162                 }
 163
 164                 if (ENABLE_FEATURE_CLEAN_UP)
 165                         fclose(fp);
 166
 167  end_parse:     /* nothing */ ;
 168         }
 169
 170         umask(0);
 171         if (!delete) {
 172                 if (sscanf(temp, "%d:%d", &major, &minor) != 2)
 173                         return;
 174                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
 175                         bb_perror_msg_and_die("mknod %s", device_name);
 176
 177                 if (major == root_major && minor == root_minor)
 178                         symlink(device_name, "root");
 179
 180                 if (ENABLE_FEATURE_MDEV_CONF)
 181                         chown(device_name, uid, gid);
 182         }
 183         if (command) {
 184                 /* setenv will leak memory, so use putenv */
 185                 char *s = xasprintf("MDEV=%s", device_name);
 186                 putenv(s);
 187                 if (system(command) == -1)
 188                         bb_perror_msg_and_die("cannot run %s", command);
 189                 s[4] = '\0';
 190                 unsetenv(s);
 191                 free(s);
 192                 free(command);
 193         }
 194         if (delete)
 195                 remove_file(device_name, FILEUTILS_FORCE);
 196 }
 197
 198 /* File callback for /sys/ traversal */
 199 static int fileAction(const char *fileName, struct stat *statbuf,
 200                       void *userData, int depth)
 201 {
 202         size_t len = strlen(fileName) - 4;
 203         char *scratch = userData;
 204
 205         if (strcmp(fileName + len, "/dev"))
 206                 return FALSE;
 207
 208         strcpy(scratch, fileName);
 209         scratch[len] = 0;
 210         make_device(scratch, 0);
 211
 212         return TRUE;
 213 }
 214
 215 /* Directory callback for /sys/ traversal */
 216 static int dirAction(const char *fileName, struct stat *statbuf,
 217                       void *userData, int depth)
 218 {
 219         return (depth >= MAX_SYSFS_DEPTH ? SKIP : TRUE);
 220 }
 221
 222 /* For the full gory details, see linux/Documentation/firmware_class/README
 223  *
 224  * Firmware loading works like this:
 225  * - kernel sets FIRMWARE env var
 226  * - userspace checks /lib/firmware/$FIRMWARE
 227  * - userspace waits for /sys/$DEVPATH/loading to appear
 228  * - userspace writes "1" to /sys/$DEVPATH/loading
 229  * - userspace copies /lib/firmware/$FIRMWARE into /sys/$DEVPATH/data
 230  * - userspace writes "0" (worked) or "-1" (failed) to /sys/$DEVPATH/loading
 231  * - kernel loads firmware into device
 232  */
 233 static void load_firmware(const char *const firmware, const char *const sysfs_path)
 234 {
 235         int cnt;
 236         int firmware_fd, loading_fd, data_fd;
 237
 238         /* check for $FIRMWARE from kernel */
 239         /* XXX: dont bother: open(NULL) works same as open("no-such-file")
 240          * if (!firmware)
 241          *      return;
 242          */
 243
 244         /* check for /lib/firmware/$FIRMWARE */
 245         xchdir("/lib/firmware");
 246         firmware_fd = xopen(firmware, O_RDONLY);
 247
 248         /* in case we goto out ... */
 249         data_fd = -1;
 250
 251         /* check for /sys/$DEVPATH/loading ... give 30 seconds to appear */
 252         xchdir(sysfs_path);
 253         for (cnt = 0; cnt < 30; ++cnt) {
 254                 loading_fd = open("loading", O_WRONLY);
 255                 if (loading_fd == -1)
 256                         sleep(1);
 257                 else
 258                         break;
 259         }
 260         if (loading_fd == -1)
 261                 goto out;
 262
 263         /* tell kernel we're loading by `echo 1 > /sys/$DEVPATH/loading` */
 264         if (write(loading_fd, "1", 1) != 1)
 265                 goto out;
 266
 267         /* load firmware by `cat /lib/firmware/$FIRMWARE > /sys/$DEVPATH/data */
 268         data_fd = open("data", O_WRONLY);
 269         if (data_fd == -1)
 270                 goto out;
 271         cnt = bb_copyfd_eof(firmware_fd, data_fd);
 272
 273         /* tell kernel result by `echo [0|-1] > /sys/$DEVPATH/loading` */
 274         if (cnt > 0)
 275                 write(loading_fd, "0", 1);
 276         else
 277                 write(loading_fd, "-1", 2);
 278
 279  out:
 280         if (ENABLE_FEATURE_CLEAN_UP) {
 281                 close(firmware_fd);
 282                 close(loading_fd);
 283                 close(data_fd);
 284         }
 285 }
 286
 287 int mdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 288 int mdev_main(int argc, char **argv)
 289 {
 290         char *action;
 291         char *env_path;
 292         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 293
 294         xchdir("/dev");
 295
 296         if (argc == 2 && !strcmp(argv[1],"-s")) {
 297
 298                 /* Scan:
 299                  * mdev -s
 300                  */
 301
 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         } else {
 317
 318                 /* Hotplug:
 319                  * env ACTION=... DEVPATH=... mdev
 320                  * ACTION can be "add" or "remove"
 321                  * DEVPATH is like "/block/sda" or "/class/input/mice"
 322                  */
 323
 324                 action = getenv("ACTION");
 325                 env_path = getenv("DEVPATH");
 326                 if (!action || !env_path)
 327                         bb_show_usage();
 328
 329                 sprintf(temp, "/sys%s", env_path);
 330                 if (!strcmp(action, "remove"))
 331                         make_device(temp, 1);
 332                 else if (!strcmp(action, "add")) {
 333                         make_device(temp, 0);
 334
 335                         if (ENABLE_FEATURE_MDEV_LOAD_FIRMWARE)
 336                                 load_firmware(getenv("FIRMWARE"), temp);
 337                 }
 338         }
 339
 340         if (ENABLE_FEATURE_CLEAN_UP)
 341                 RELEASE_CONFIG_BUFFER(temp);
 342
 343         return 0;
 344 }