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 "busybox.h"
  22 #include "xregex.h"
  23
  24 #define DEV_PATH        "/dev"
  25
  26 #include <busybox.h>
  27
  28 /* mknod in /dev based on a path like "/sys/block/hda/hda1" */
  29 static void make_device(char *path)
  30 {
  31         char *device_name,*s;
  32         int major,minor,type,len,fd;
  33         int mode=0660;
  34         uid_t uid=0;
  35         gid_t gid=0;
  36
  37         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
  38
  39         /* Try to read major/minor string */
  40
  41         snprintf(temp, PATH_MAX, "%s/dev", path);
  42         fd = open(temp, O_RDONLY);
  43         len = read(fd, temp, PATH_MAX-1);
  44         if (len<1) goto end;
  45         temp[--len] = 0; // remove trailing \n
  46         close(fd);
  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         major = minor = 0;
  53         for (s = temp; *s; s++) {
  54                 if (*s == ':') {
  55                         major = minor;
  56                         minor = 0;
  57                 } else {
  58                         minor *= 10;
  59                         minor += (*s) - '0';
  60                 }
  61         }
  62
  63         /* If we have a config file, look up permissions for this device */
  64
  65         if (ENABLE_FEATURE_MDEV_CONF) {
  66                 char *conf,*pos,*end;
  67
  68                 /* mmap the config file */
  69                 if (-1!=(fd=open("/etc/mdev.conf",O_RDONLY))) {
  70                         len=lseek(fd,0,SEEK_END);
  71                         conf=mmap(NULL,len,PROT_READ,MAP_PRIVATE,fd,0);
  72                         if (conf) {
  73                                 int line=0;
  74
  75                                 /* Loop through lines in mmaped file*/
  76                                 for (pos=conf;pos-conf<len;) {
  77                                         int field;
  78                                         char *end2;
  79
  80                                         line++;
  81                                         /* find end of this line */
  82                                         for(end=pos;end-conf<len && *end!='\n';end++);
  83
  84                                         /* Three fields: regex, uid:gid, mode */
  85                                         for (field=3;field;field--) {
  86                                                 /* Skip whitespace */
  87                                                 while (pos<end && isspace(*pos)) pos++;
  88                                                 if (pos==end || *pos=='#') break;
  89                                                 for (end2=pos;
  90                                                         end2<end && !isspace(*end2) && *end2!='#'; end2++);
  91                                                 switch(field) {
  92                                                         /* Regex to match this device */
  93                                                         case 3:
  94                                                         {
  95                                                                 char *regex=strndupa(pos,end2-pos);
  96                                                                 regex_t match;
  97                                                                 regmatch_t off;
  98                                                                 int result;
  99
 100                                                                 /* Is this it? */
 101                                                                 xregcomp(&match,regex,REG_EXTENDED);
 102                                                                 result=regexec(&match,device_name,1,&off,0);
 103                                                                 regfree(&match);
 104
 105                                                                 /* If not this device, skip rest of line */
 106                                                                 if(result || off.rm_so
 107                                                                         || off.rm_eo!=strlen(device_name))
 108                                                                                 goto end_line;
 109
 110                                                                 break;
 111                                                         }
 112                                                         /* uid:gid */
 113                                                         case 2:
 114                                                         {
 115                                                                 char *s2;
 116
 117                                                                 /* Find : */
 118                                                                 for(s=pos;s<end2 && *s!=':';s++);
 119                                                                 if(s==end2) goto end_line;
 120
 121                                                                 /* Parse UID */
 122                                                                 uid=strtoul(pos,&s2,10);
 123                                                                 if(s!=s2) {
 124                                                                         struct passwd *pass;
 125                                                                         pass=getpwnam(strndupa(pos,s-pos));
 126                                                                         if(!pass) goto end_line;
 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                                                                         grp=getgrnam(strndupa(s,end2-s));
 135                                                                         if(!grp) 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) goto end_line;
 145                                                                 goto found_device;
 146                                                         }
 147                                                 }
 148                                                 pos=end2;
 149                                         }
 150 end_line:
 151                                         /* Did everything parse happily? */
 152                                         if (field && field!=3)
 153                                                         bb_error_msg_and_die("Bad line %d",line);
 154
 155                                         /* Next line */
 156                                         pos=++end;
 157                                 }
 158 found_device:
 159                                 munmap(conf,len);
 160                         }
 161                         close(fd);
 162                 }
 163         }
 164
 165         sprintf(temp, "%s/%s", DEV_PATH, device_name);
 166         umask(0);
 167         if (mknod(temp, mode | type, makedev(major, minor)) && errno != EEXIST)
 168                 bb_perror_msg_and_die("mknod %s failed", temp);
 169
 170         if (ENABLE_FEATURE_MDEV_CONF) chown(temp,uid,gid);
 171
 172 end:
 173         RELEASE_CONFIG_BUFFER(temp);
 174 }
 175
 176 /* Recursive search of /sys/block or /sys/class.  path must be a writeable
 177  * buffer of size PATH_MAX containing the directory string to start at. */
 178
 179 static void find_dev(char *path)
 180 {
 181         DIR *dir;
 182         int len=strlen(path);
 183
 184         if (!(dir = opendir(path)))
 185                 bb_perror_msg_and_die("No %s",path);
 186
 187         for (;;) {
 188                 struct dirent *entry = readdir(dir);
 189
 190                 if (!entry) break;
 191
 192                 /* Skip "." and ".." (also skips hidden files, which is ok) */
 193
 194                 if (entry->d_name[0]=='.') continue;
 195
 196                 if (entry->d_type == DT_DIR) {
 197                         snprintf(path+len, PATH_MAX-len, "/%s", entry->d_name);
 198                         find_dev(path);
 199                         path[len] = 0;
 200                 }
 201
 202                 /* If there's a dev entry, mknod it */
 203
 204                 if (strcmp(entry->d_name, "dev")) make_device(path);
 205         }
 206
 207         closedir(dir);
 208 }
 209
 210 int mdev_main(int argc, char *argv[])
 211 {
 212         if (argc > 1) {
 213                 if (argc == 2 && !strcmp(argv[1],"-s")) {
 214                         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 215                         strcpy(temp,"/sys/block");
 216                         find_dev(temp);
 217                         strcpy(temp,"/sys/class");
 218                         find_dev(temp);
 219                         if(ENABLE_FEATURE_CLEAN_UP)
 220                                 RELEASE_CONFIG_BUFFER(temp);
 221                         return 0;
 222                 } else bb_show_usage();
 223         }
 224
 225 /* hotplug support goes here */
 226
 227         return 0;
 228 }