text: /* mdev.c - Populate /dev directory and handle hotplug events
   *
   * Copyright 2005, 2008 Rob Landley <rob@landley.net>
   * Copyright 2005 Frank Sorenson <frank@tuxrocks.com>
  
  USE_MDEV(NEWTOY(mdev, "s", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_UMASK))
  
  config MDEV
    bool "mdev"
    default n
    help
      usage: mdev [-s]
  
      Create devices in /dev using information from /sys.
  
      -s	Scan all entries in /sys to populate /dev
  
  config MDEV_CONF
    bool "Configuration file for mdev"
    default y
    depends on MDEV
    help
      The mdev config file (/etc/mdev.conf) contains lines that look like:
      hd[a-z][0-9]* 0:3 660
      (sd[a-z]) root:disk 660 =usb_storage
  
      Each line must contain three whitespace separated fields. The first
      field is a regular expression matching one or more device names,
      the second and third fields are uid:gid and file permissions for
      matching devices. Fourth field is optional. It could be used to change
      device name (prefix '='), path (prefix '=' and postfix '/') or create a
      symlink (prefix '>').
  */
  
  #include "toys.h"
  #include <stdbool.h>
  
  // mknod in /dev based on a path like "/sys/block/hda/hda1"
  static void make_device(char *path)
  {
    char *device_name = 0, *custom_name = 0, *s, *temp;
    bool create_symlink = false;
    int major = 0, minor = 0, type, len, fd, mode = 0660;
    uid_t uid = 0;
    gid_t gid = 0;
  
    if (path) {
  
      // Try to read major/minor string, returning if we can't
      temp = strrchr(path, '/');
      fd = open(path, O_RDONLY);
      *temp = 0;
      len = read(fd, toybuf, 64);
      close(fd);
      if (len<1) return;
      toybuf[len] = 0;
  
      // Determine device type, major and minor
  
      type = path[5]=='c' ? S_IFCHR : S_IFBLK;
      sscanf(toybuf, "%u:%u", &major, &minor);
    } else {
      // if (!path), do hotplug
  
      if (!(temp = getenv("MODALIAS"))) xrun((char *[]){"modprobe", temp, 0});
      if (!(temp = getenv("SUBSYSTEM"))) return;
      type = strcmp(temp, "block") ? S_IFCHR : S_IFBLK;
      if (!(temp = getenv("MAJOR"))) return;
      sscanf(temp, "%u", &major);
      if (!(temp = getenv("MINOR"))) return;
      sscanf(temp, "%u", &minor);
      if (!(path = getenv("DEVPATH"))) return;
      device_name = getenv("DEVNAME");
    }
    if (!device_name)
      device_name = strrchr(path, '/') + 1;
  
    // as in linux/drivers/base/core.c, device_get_devnode()
    while ((temp = strchr(device_name, '!'))) {
      *temp = '/';
    }
  
    // If we have a config file, look up permissions for this device
  
    if (CFG_MDEV_CONF) {
      char *conf, *pos, *end;
      bool optional_field_valid = false;
  
      // mmap the config file
      if (-1!=(fd = open("/etc/mdev.conf", O_RDONLY))) {
        int line = 0;
  
        len = fdlength(fd);
        conf = xmmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  
        // Loop through lines in mmaped file
        for (pos = conf; pos-conf<len;) {
          int field;
          char *end2;
  
          line++;
          // find end of this line
          for(end = pos; end-conf<len && *end!='\n'; end++);
  
          // Four fields (last is optional): regex, uid:gid, mode [, name|path ]
          // For example: (sd[a-z])1  root:disk 660 =usb_storage_p1
          for (field = 4; field; field--) {
            // Skip whitespace
            while (pos<end && isspace(*pos)) pos++;
            if (pos==end || *pos=='#') break;
            for (end2 = pos;
              end2<end && !isspace(*end2) && *end2!='#'; end2++);
            switch(field) {
              // Regex to match this device
              case 4:
              {
                char *regex = strndup(pos, end2-pos);
                regex_t match;
                regmatch_t off;
                int result;
  
                // Is this it?
                xregcomp(&match, regex, REG_EXTENDED);
                result=regexec(&match, device_name, 1, &off, 0);
                regfree(&match);
                free(regex);
  
                // If not this device, skip rest of line
                if (result || off.rm_so
                  || off.rm_eo!=strlen(device_name))
                    goto end_line;
  
                break;
              }
              // uid:gid
              case 3:
              {
                char *s2;
  
                // Find :
                for(s = pos; s<end2 && *s!=':'; s++);
                if (s==end2) goto end_line;
  
                // Parse UID
                uid = strtoul(pos,&s2,10);
                if (s!=s2) {
                  struct passwd *pass;
                  char *str = strndup(pos, s-pos);
                  pass = getpwnam(str);
                  free(str);
                  if (!pass) goto end_line;
                  uid = pass->pw_uid;
                }
                s++;
                // parse GID
                gid = strtoul(s,&s2,10);
                if (end2!=s2) {
                  struct group *grp;
                  char *str = strndup(s, end2-s);
                  grp = getgrnam(str);
                  free(str);
                  if (!grp) goto end_line;
                  gid = grp->gr_gid;
                }
                break;
              }
              // mode
              case 2:
              {
                char *beg_pos = pos;
                mode = strtoul(pos, &pos, 8);
                if (pos == beg_pos) {
                  // The line is bad because mode setting could not be
                  // converted to numeric value.
                  goto end_line;
                }
                break;
              }
              // Try to look for name or path (optional field)
              case 1:
              {
                if(pos < end2){
                  //char *name = strndup(pos, end2-pos);
                  char *name = malloc(end2-pos+1);
                  if(name){
                    strncpy(name, pos, end2-pos+1);
                    name[end2-pos] = '\0';
                    switch(name[0]){
                      case '>':
                        create_symlink = true;
                      case '=':
                        custom_name = strdup(&name[1]);
                        break;
                      case '!':
                        device_name = NULL;
                        break;
                      default:
                        free(name);
                        goto end_line;
                    }
                    free(name);
                    optional_field_valid = true;
                  }
                }
                goto found_device;
              }
            }
            pos=end2;
          }
  end_line:
          // Did everything parse happily?
          // Note: Last field is optional.
          if ((field>1 || (field==1 && !optional_field_valid)) && field!=4)
            error_exit("Bad line %d", line);
          // Next line
          pos = ++end;
        }
  found_device:
        munmap(conf, len);
      }
      close(fd);
    }
  
    if(device_name) {
      if(custom_name) {
        sprintf(toybuf, "/dev/%s", custom_name);
        if(custom_name[strlen(custom_name) - 1] == '/') {
          DIR *dir;
          dir = opendir(toybuf);
          if(dir) closedir(dir);
          else mkdir(toybuf, 0755);
        }
      }
      else
        sprintf(toybuf, "/dev/%s", device_name);
  
      if ((temp=getenv("ACTION")) && !strcmp(temp, "remove")) {
          unlink(toybuf);
          return;
      }
  
        if (strchr(device_name, '/')) mkpath(toybuf);
        if (mknod(toybuf, mode | type, dev_makedev(major, minor)) &&
            errno != EEXIST)
          perror_exit("mknod %s failed", toybuf);
        if(create_symlink){
          char *symlink_name = malloc(sizeof("/dev/") + strlen(device_name) + 1);
          if(symlink_name == NULL)
            perror_exit("malloc failed while creating symlink to %s", toybuf);
          sprintf(symlink_name, "/dev/%s", device_name);
          if(symlink(toybuf, symlink_name)){
            free(symlink_name);
            perror_exit("symlink creation failed for %s", toybuf);
          }
          free(symlink_name);
        }
  
        if (type == S_IFBLK) close(open(toybuf, O_RDONLY)); // scan for partitions
  
        if (CFG_MDEV_CONF) mode=chown(toybuf, uid, gid);
    }
  }
  
  static int callback(struct dirtree *node)
  {
    // Entries in /sys/class/block aren't char devices, so skip 'em.  (We'll
    // get block devices out of /sys/block.)
    if(!strcmp(node->name, "block")) return 0;
  
    // Does this directory have a "dev" entry in it?
    // This is path based because the hotplug callbacks are
    if (S_ISDIR(node->st.st_mode) || S_ISLNK(node->st.st_mode)) {
      int len=4;
      char *dev = dirtree_path(node, &len);
      strcpy(dev+len, "/dev");
      if (!access(dev, R_OK)) make_device(dev);
      free(dev);
    }
  
    // Circa 2.6.25 the entries more than 2 deep are all either redundant
    // (mouse#, event#) or unnamed (every usb_* entry is called "device").
  
    if (node->parent && node->parent->parent) return 0;
    return DIRTREE_RECURSE|DIRTREE_SYMFOLLOW;
  }
  
  void mdev_main(void)
  {
    // Handle -s
  
    if (toys.optflags) {
      dirtree_read("/sys/class", callback);
      if (!access("/sys/block", R_OK)) dirtree_read("/sys/block", callback);
    } else { // hotplug support
      make_device(NULL);
    }
  }
  