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
  27 #include <busybox.h>
  28
  29 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  30 static void make_device(char *path)
  31 {
  32         char *device_name,*s;
  33         int major,minor,type,len,fd;
  34         int mode=0660;
  35         uid_t uid=0;
  36         gid_t gid=0;
  37
  38         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
  39
  40         /* Try to read major/minor string */
  41
  42         snprintf(temp, PATH_MAX, "%s/dev", path);
  43         fd = open(temp, O_RDONLY);
  44         len = read(fd, temp, PATH_MAX-1);
  45         if (len<1) goto end;
  46         temp[--len] = 0; // remove trailing \n
  47         close(fd);
  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         major = minor = 0;
  54         for (s = temp; *s; s++) {
  55                 if (*s == ':') {
  56                         major = minor;
  57                         minor = 0;
  58                 } else {
  59                         minor *= 10;
  60                         minor += (*s) - '0';
  61                 }
  62         }
  63
  64         /* If we have a config file, look up permissions for this device */
  65
  66         if (ENABLE_FEATURE_MDEV_CONF) {
  67                 char *conf,*pos,*end;
  68
  69                 /* mmap the config file */
  70                 if (-1!=(fd=open("/etc/mdev.conf",O_RDONLY))) {
  71                         len=lseek(fd,0,SEEK_END);
  72                         conf=mmap(NULL,len,PROT_READ,MAP_PRIVATE,fd,0);
  73                         if (conf) {
  74                                 int line=0;
  75
  76                                 /* Loop through lines in mmaped file*/
  77                                 for (pos=conf;pos-conf<len;) {
  78                                         int field;
  79                                         char *end2;
  80
  81                                         line++;
  82                                         /* find end of this line */
  83                                         for(end=pos;end-conf<len && *end!='\n';end++);
  84
  85                                         /* Three fields: regex, uid:gid, mode */
  86                                         for (field=3;field;field--) {
  87                                                 /* Skip whitespace */
  88                                                 while (pos<end && isspace(*pos)) pos++;
  89                                                 if (pos==end || *pos=='#') break;
  90                                                 for (end2=pos;
  91                                                         end2<end && !isspace(*end2) && *end2!='#'; end2++);
  92                                                 switch(field) {
  93                                                         /* Regex to match this device */
  94                                                         case 3:
  95                                                         {
  96                                                                 char *regex=strndupa(pos,end2-pos);
  97                                                                 regex_t match;
  98                                                                 regmatch_t off;
  99                                                                 int result;
 100
 101                                                                 /* Is this it? */
 102                                                                 xregcomp(&match,regex,REG_EXTENDED);
 103                                                                 result=regexec(&match,device_name,1,&off,0);
 104                                                                 regfree(&match);
 105
 106                                                                 /* If not this device, skip rest of line */
 107                                                                 if(result || off.rm_so
 108                                                                         || off.rm_eo!=strlen(device_name))
 109                                                                                 goto end_line;
 110
 111                                                                 break;
 112                                                         }
 113                                                         /* uid:gid */
 114                                                         case 2:
 115                                                         {
 116                                                                 char *s2;
 117
 118                                                                 /* Find : */
 119                                                                 for(s=pos;s<end2 && *s!=':';s++);
 120                                                                 if(s==end2) goto end_line;
 121
 122                                                                 /* Parse UID */
 123                                                                 uid=strtoul(pos,&s2,10);
 124                                                                 if(s!=s2) {
 125                                                                         struct passwd *pass;
 126                                                                         pass=getpwnam(strndupa(pos,s-pos));
 127                                                                         if(!pass) goto end_line;
 128                                                                         uid=pass->pw_uid;
 129                                                                 }
 130                                                                 s++;
 131                                                                 /* parse GID */
 132                                                                 gid=strtoul(s,&s2,10);
 133                                                                 if(end2!=s2) {
 134                                                                         struct group *grp;
 135                                                                         grp=getgrnam(strndupa(s,end2-s));
 136                                                                         if(!grp) goto end_line;
 137                                                                         gid=grp->gr_gid;
 138                                                                 }
 139                                                                 break;
 140                                                         }
 141                                                         /* mode */
 142                                                         case 1:
 143                                                         {
 144                                                                 mode=strtoul(pos,&pos,8);
 145                                                                 if(pos!=end2) goto end_line;
 146                                                                 goto found_device;
 147                                                         }
 148                                                 }
 149                                                 pos=end2;
 150                                         }
 151 end_line:
 152                                         /* Did everything parse happily? */
 153                                         if (field && field!=3)
 154                                                         bb_error_msg_and_die("Bad line %d",line);
 155
 156                                         /* Next line */
 157                                         pos=++end;
 158                                 }
 159 found_device:
 160                                 munmap(conf,len);
 161                         }
 162                         close(fd);
 163                 }
 164         }
 165
 166         sprintf(temp, "%s/%s", DEV_PATH, device_name);
 167         umask(0);
 168         if (mknod(temp, mode | type, makedev(major, minor)) && errno != EEXIST)
 169                 bb_perror_msg_and_die("mknod %s failed", temp);
 170
 171         if (ENABLE_FEATURE_MDEV_CONF) chown(temp,uid,gid);
 172
 173 end:
 174         RELEASE_CONFIG_BUFFER(temp);
 175 }
 176
 177 /* Recursive search of /sys/block or /sys/class.  path must be a writeable
 178  * buffer of size PATH_MAX containing the directory string to start at. */
 179
 180 static void find_dev(char *path)
 181 {
 182         DIR *dir;
 183         int len=strlen(path);
 184
 185         if (!(dir = opendir(path)))
 186                 bb_perror_msg_and_die("No %s",path);
 187
 188         for (;;) {
 189                 struct dirent *entry = readdir(dir);
 190
 191                 if (!entry) break;
 192
 193                 /* Skip "." and ".." (also skips hidden files, which is ok) */
 194
 195                 if (entry->d_name[0]=='.') 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) bb_show_usage();
 231
 232                 if (!strcmp(action, "add")) {
 233                         sprintf(temp, "/sys%s", env_path);
 234                         make_device(temp);
 235                 } else if (!strcmp(action, "remove")) {
 236                         sprintf(temp, "%s/%s", DEV_PATH, strrchr(env_path, '/') + 1);
 237                         unlink(temp);
 238                 }
 239         }
 240
 241         if(ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
 242         return 0;
 243 }