util-linux/mdev.c

   1 /* vi:set ts=4:
   2  *
   3  * mdev - Mini udev for busybox
   4  *
   5  * Copyright 2005 Rob Landley <rob@landley.net>
   6  * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   9  */
  10
  11 #include <ctype.h>
  12 #include <dirent.h>
  13 #include <errno.h>
  14 #include <fcntl.h>
  15 #include <stdio.h>
  16 #include <string.h>
  17 #include <sys/mman.h>
  18 #include <sys/stat.h>
  19 #include <sys/types.h>
  20 #include <unistd.h>
  21 #include <stdlib.h>
  22 #include "busybox.h"
  23 #include "xregex.h"
  24
  25 #define DEV_PATH        "/dev"
  26 #define MDEV_CONF       "/etc/mdev.conf"
  27
  28 #include <busybox.h>
  29
  30 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  31 static void make_device(char *path)
  32 {
  33         char *device_name, *s;
  34         int major, minor, type, len, fd;
  35         int mode = 0660;
  36         uid_t uid = 0;
  37         gid_t gid = 0;
  38
  39         RESERVE_CONFIG_BUFFER(temp, PATH_MAX);
  40
  41         /* Try to read major/minor string */
  42
  43         snprintf(temp, PATH_MAX, "%s/dev", path);
  44         fd = open(temp, O_RDONLY);
  45         len = read(fd, temp, PATH_MAX-1);
  46         close(fd);
  47         if (len < 1) goto end;
  48
  49         /* Determine device name, type, major and minor */
  50
  51         device_name = strrchr(path, '/') + 1;
  52         type = strncmp(path+5, "block/", 6) ? S_IFCHR : S_IFBLK;
  53         if (sscanf(temp, "%d:%d", &major, &minor) != 2)
  54                 goto end;
  55
  56         /* If we have a config file, look up permissions for this device */
  57
  58         if (ENABLE_FEATURE_MDEV_CONF) {
  59                 char *conf, *pos, *end;
  60
  61                 /* mmap the config file */
  62                 if (-1 != (fd=open(MDEV_CONF,O_RDONLY))) {
  63                         len = lseek(fd, 0, SEEK_END);
  64                         conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  65                         if (conf) {
  66                                 int line = 0;
  67
  68                                 /* Loop through lines in mmaped file*/
  69                                 for (pos=conf; pos-conf<len;) {
  70                                         int field;
  71                                         char *end2;
  72
  73                                         line++;
  74                                         /* find end of this line */
  75                                         for(end=pos; end-conf<len && *end!='\n'; end++)
  76                                                 ;
  77
  78                                         /* Three fields: regex, uid:gid, mode */
  79                                         for (field=3; field; field--) {
  80                                                 /* Skip whitespace */
  81                                                 while (pos<end && isspace(*pos))
  82                                                         pos++;
  83                                                 if (pos==end || *pos=='#')
  84                                                         break;
  85                                                 for (end2=pos; end2<end && !isspace(*end2) && *end2!='#'; end2++)
  86                                                         ;
  87
  88                                                 switch (field) {
  89                                                         /* Regex to match this device */
  90                                                         case 3:
  91                                                         {
  92                                                                 char *regex = strndupa(pos,end2-pos);
  93                                                                 regex_t match;
  94                                                                 regmatch_t off;
  95                                                                 int result;
  96
  97                                                                 /* Is this it? */
  98                                                                 xregcomp(&match,regex,REG_EXTENDED);
  99                                                                 result = regexec(&match,device_name,1,&off,0);
 100                                                                 regfree(&match);
 101
 102                                                                 /* If not this device, skip rest of line */
 103                                                                 if (result || off.rm_so || off.rm_eo!=strlen(device_name))
 104                                                                         goto end_line;
 105
 106                                                                 break;
 107                                                         }
 108                                                         /* uid:gid */
 109                                                         case 2:
 110                                                         {
 111                                                                 char *s2;
 112
 113                                                                 /* Find : */
 114                                                                 for(s=pos; s<end2 && *s!=':'; s++)
 115                                                                         ;
 116                                                                 if (s == end2)
 117                                                                         goto end_line;
 118
 119                                                                 /* Parse UID */
 120                                                                 uid = strtoul(pos,&s2,10);
 121                                                                 if (s != s2) {
 122                                                                         struct passwd *pass;
 123                                                                         pass = getpwnam(strndupa(pos,s-pos));
 124                                                                         if (!pass)
 125                                                                                 goto end_line;
 126                                                                         uid = pass->pw_uid;
 127                                                                 }
 128                                                                 s++;
 129                                                                 /* parse GID */
 130                                                                 gid = strtoul(s,&s2,10);
 131                                                                 if (end2 != s2) {
 132                                                                         struct group *grp;
 133                                                                         grp = getgrnam(strndupa(s,end2-s));
 134                                                                         if (!grp)
 135                                                                                 goto end_line;
 136                                                                         gid = grp->gr_gid;
 137                                                                 }
 138                                                                 break;
 139                                                         }
 140                                                         /* mode */
 141                                                         case 1:
 142                                                         {
 143                                                                 mode = strtoul(pos,&pos,8);
 144                                                                 if (pos != end2)
 145                                                                         goto end_line;
 146                                                                 else
 147                                                                         goto found_device;
 148                                                         }
 149                                                 }
 150                                                 pos = end2;
 151                                         }
 152 end_line:
 153                                         /* Did everything parse happily? */
 154                                         if (field && field!=3)
 155                                                 bb_error_msg_and_die("Bad line %d",line);
 156
 157                                         /* Next line */
 158                                         pos = ++end;
 159                                 }
 160 found_device:
 161                                 munmap(conf, len);
 162                         }
 163                         close(fd);
 164                 }
 165         }
 166
 167         sprintf(temp, "%s/%s", DEV_PATH, device_name);
 168         umask(0);
 169         if (mknod(temp, mode | type, makedev(major, minor)) && errno != EEXIST)
 170                 bb_perror_msg_and_die("mknod %s failed", temp);
 171
 172         if (ENABLE_FEATURE_MDEV_CONF) chown(temp,uid,gid);
 173
 174 end:
 175         RELEASE_CONFIG_BUFFER(temp);
 176 }
 177
 178 /* Recursive search of /sys/block or /sys/class.  path must be a writeable
 179  * buffer of size PATH_MAX containing the directory string to start at. */
 180
 181 static void find_dev(char *path)
 182 {
 183         DIR *dir;
 184         size_t len = strlen(path);
 185         struct dirent *entry;
 186
 187         if ((dir = opendir(path)) == NULL)
 188                 return;
 189
 190         while ((entry = readdir(dir)) != NULL) {
 191
 192                 /* Skip "." and ".." (also skips hidden files, which is ok) */
 193
 194                 if (entry->d_name[0] == '.')
 195                         continue;
 196
 197                 if (entry->d_type == DT_DIR) {
 198                         snprintf(path+len, PATH_MAX-len, "/%s", entry->d_name);
 199                         find_dev(path);
 200                         path[len] = 0;
 201                 }
 202
 203                 /* If there's a dev entry, mknod it */
 204
 205                 if (!strcmp(entry->d_name, "dev")) make_device(path);
 206         }
 207
 208         closedir(dir);
 209 }
 210
 211 int mdev_main(int argc, char *argv[])
 212 {
 213         char *action;
 214         char *env_path;
 215         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 216
 217         /* Scan */
 218
 219         if (argc == 2 && !strcmp(argv[1],"-s")) {
 220                 strcpy(temp,"/sys/block");
 221                 find_dev(temp);
 222                 strcpy(temp,"/sys/class");
 223                 find_dev(temp);
 224
 225         /* Hotplug */
 226
 227         } else {
 228                 action = getenv("ACTION");
 229                 env_path = getenv("DEVPATH");
 230             if (!action || !env_path)
 231                         bb_show_usage();
 232
 233                 if (!strcmp(action, "add")) {
 234                         sprintf(temp, "/sys%s", env_path);
 235                         make_device(temp);
 236                 } else if (!strcmp(action, "remove")) {
 237                         sprintf(temp, "%s/%s", DEV_PATH, strrchr(env_path, '/') + 1);
 238                         unlink(temp);
 239                 }
 240         }
 241
 242         if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
 243         return 0;
 244 }