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