#!/bin/sh -e

UDEVSTART=/sbin/udevstart

# defaults
tmpfs_size="10M"
udev_root="/dev"

[ -x $UDEVSTART ] || exit 0

. /etc/udev/udev.conf

##############################################################################

# we need to unmount /dev/pts/ and remount it later over the tmpfs
unmount_devpts() {
  if mountpoint -q /dev/pts/; then
    umount -l /dev/pts/
  fi

  if mountpoint -q /dev/shm/; then
    umount -l /dev/shm/
  fi
}

# mount a tmpfs over /dev, if somebody did not already do it
mount_tmpfs() {
  if grep -E -q "^[^[:space:]]+ /dev tmpfs" /proc/mounts; then
    return 0
  fi

  # /dev/.static/dev/ is used by MAKEDEV to access the real /dev/ directory.
  # /etc/udev/ is recycled as a temporary mount point because it's the only
  # directory which is guaranteed to be available.
  mount -n -o bind /dev /etc/udev

  if ! mount -n -o size=$tmpfs_size,mode=0755 -t tmpfs tmpfs /dev; then
    umount /etc/udev
    echo "udev requires tmpfs support, not started."
    exit 1
  fi

  # using ln to test if /dev works, because touch is in /usr/bin/
  if ln -s test /dev/test-file; then
    rm /dev/test-file
  else
    echo "udev requires tmpfs support, not started."
    umount /etc/udev
    umount /dev
    exit 1
  fi

  mkdir -p /dev/.static/dev
  chmod 700 /dev/.static/
  # Make sure it's busybox mount we're using. util-linux mount doesn't handle
  # -o move. 
  busybox mount -n -o move /etc/udev /dev/.static/dev
}

# I hate this hack.  -- Md
make_extra_nodes() {
  [ -e /etc/udev/links.conf ] || return 0
  grep '^[^#]' /etc/udev/links.conf | \
  while read type name arg1; do
    [ "$type" -a "$name" -a ! -e "/dev/$name" -a ! -L "/dev/$name" ] ||continue
    case "$type" in
      L) ln -s $arg1 /dev/$name ;;
      D) mkdir -p /dev/$name ;;
      M) mknod -m 600 /dev/$name $arg1 ;;
      *) echo "links.conf: unparseable line ($type $name $arg1)" ;;
    esac
  done
}

# this function is duplicated in preinst, postinst and d-i
supported_kernel() {
  case "$(uname -r)" in
    2.[012345].*|2.6.[0-9]|2.6.[0-9][!0-9]*) return 1 ;;
    2.6.1[01]|2.6.1[01][!0-9]*) return 1 ;;
  esac
  return 0
}

# shell version of /usr/bin/tty
my_tty() {
  [ -x /bin/readlink ] || return 0
  [ -e /proc/self/fd/0 ] || return 0
  readlink --silent /proc/self/fd/0 || true
}

warn_if_interactive() {
  if [ "$RUNLEVEL" = "S" -a "$PREVLEVEL" = "N" ]; then
    return 0
  fi

  TTY=$(my_tty)
  if [ -z "$TTY" -o "$TTY" = "/dev/console" ]; then
    return 0
  fi

  printf "\n\n\nIt has been detected that the command\n\n\t$0 $*\n\n"
  printf "has been run from an interactive shell.\n"
  printf "It will probably not do what you expect, so this script will wait\n"
  printf "60 seconds before continuing. Press ^C to stop it.\n"
  printf "RUNNING THIS COMMAND IS HIGHLY DISCOURAGED!\n\n\n\n"
  sleep 60
}

##############################################################################

if ! supported_kernel; then
  echo "udev requires a kernel >= 2.6.12, not started."
  exit 1
fi

if [ ! -e /proc/filesystems ]; then
  echo "udev requires a mounted procfs, not started."
  exit 1
fi

if ! grep -q '[[:space:]]tmpfs$' /proc/filesystems; then
  echo "udev requires tmpfs support, not started."
  exit 1
fi

if [ ! -d /sys/class/ ]; then
  echo "udev requires a mounted sysfs, not started."
  exit 1
fi

if [ ! -e /proc/sys/kernel/hotplug ]; then
  echo "udev requires hotplug support, not started."
  exit 1
fi

##############################################################################

# When modifying this script, do not forget that between the time that
# the new /dev has been mounted and udevstart has been run there will be
# no /dev/null. This also means that you cannot use the "&" shell command.

case "$1" in
  start)
    if [ -e "$udev_root/.udevdb" ]; then
      if mountpoint -q /dev/; then
        TMPFS_MOUNTED=1
      else
        echo ".udevdb already exists on the old $udev_root!"
      fi
    fi
    warn_if_interactive

    #echo /sbin/udevsend > /proc/sys/kernel/hotplug
    echo "" > /proc/sys/kernel/hotplug
    udevsend
    if [ "$UDEV_DISABLED" = "yes" ]; then
      echo "udev disabled on the kernel command line, not started."
      exit 0
    fi

    if [ ! "$TMPFS_MOUNTED" ]; then
      unmount_devpts
      mount_tmpfs
      [ -d /proc/1 ] || mount -n /proc
      # if this directory is not present /dev will not be updated by udev
      mkdir /dev/.udevdb/
      echo "Creating initial device nodes..."
      udevstart
    fi
    make_extra_nodes
    ;;
  stop)
    warn_if_interactive
    start-stop-daemon --stop --exec /sbin/udevd --quiet
    unmount_devpts
    if [ -d /dev/.static/dev/ ]; then
      umount -l /dev/.static/dev/ || true
    fi
    echo "Unmounting /dev..."
    # unmounting with -l should never fail
    if ! umount -l /dev; then
      exit 1
    fi
    ;;
  restart|force-reload)
    start-stop-daemon --stop --exec /sbin/udevd --quiet
    log_begin_msg "Recreating device nodes..."
    udevstart
    make_extra_nodes
    log_end_msg 0
    ;;
  *)
    echo "Usage: /etc/init.d/udev {start|stop|restart|force-reload}"
    exit 1
    ;;
esac

exit 0
