crosh

#!/bin/dash
# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

TRY_BASH=1
if echo "$@" | grep -q -- "--dash"; then
  TRY_BASH=0
fi

# NOTE: This script *almost* works in dash.  Unfortunately, dash is missing
# the 'history' builtin and readline support is missing from the 'read'
# builtin.
#
# Please test that any changes continue to work in dash by running
# '/build/board-name/bin/dash crosh --dash' before checking them in.

if type "history" 2>/dev/null | grep -q "shell builtin"; then
  IS_BASH=1
else
  IS_BASH=0
fi

if [ "$TRY_BASH" = "1" -a "$IS_BASH" != "1" -a -x "/bin/bash" ]; then
  # Relaunch in bash if we can.
  exec /bin/bash $0 "$@"
fi

#
# Please keep the help text in alphabetical order!
#
HELP='
 exit
  Exit crosh.

 help
  Display this help.

 help_advanced
  Display the help for more advanced commands, mainly used for debugging.

 ping [-c count] [-i interval] [-n] [-s packetsize] [-W waittime] <destination>
  Send ICMP ECHO_REQUEST packets to a network host.  If <destination> is "gw"
  then the next hop gateway for the default route is used.

 ssh [optional args...]
  Starts the ssh subsystem if invoked without any arguments.
  "ssh <user> <host>", "ssh <user> <host> <port>", "ssh <user>@<host>",
  or "ssh <user>@<host> <port>" connect without entering the subsystem.

 ssh_forget_host
  Remove a host from the list of known ssh hosts.  This command displays
  a menu of known hosts and prompts for the host to forget.

 top
  Run top.
'

HELP_ADVANCED='
 connectivity
  Shows connectivity status.  "connectivity help" for more details

 experimental_storage < status | enable | disable >
  Enable or disable experimental storage features.

 ff_debug [<tag_expr>] [--help] [--list_valid_tags] [--reset]
  Add and remove flimflam debugging tags.

 modem <command> [args...]
  Interact with the 3G modem. Run "modem help" for detailed help.

 modem_set_carrier carrier-name
  Configures the modem for the specified carrier.

 network_logging <wifi | cellular | ethernet>
  A function that enables a predefined set of tags useful for
  debugging the specified device.

 network_diag [--date] [--flimflam] [--link] [--show-macs] [--wifi] [--help]
   [--wifi-monitor] <host>
  A function that performs a suite of network diagnostics.  Saves a copy
  of the output to your download directory.

 rlz < status | enable | disable >
  Enable or disable RLZ.

 route [-n] [-6]
  Display the routing tables.

 set_apn [-n <network-id>] [-u <username>] [-p <password>] <apn>
  Set the APN to use when connecting to the network specified by <network-id>.
  If <network-id> is not specified, use the network-id of the currently
  registered network.

 set_apn -c
  Clear the APN to be used, so that the default APN will be used instead.

 set_arpgw <true | false>
  Turn on extra network state checking to make sure the default gateway
  is reachable.

 tpcontrol {status|taptoclick [on|off]|sensitivity [1-5]|set <property> <value>}
 tpcontrol {syntp [on|off]}
  Manually adjust advanced touchpad settings.

 tracepath [-n] <destination>[/port]
  Trace the path/route to a network host.

 wpa_debug [<debug_level>] [--help] [--list_valid_level] [--reset]
  Set wpa_supplicant debugging level.

 syslog <message>
  Logs a message to syslog.

 chaps_debug [start|stop|<log_level>]
  Sets the chapsd logging level. No arguments will start verbose logging.
'

CHROMEOS_INSTALL=/usr/sbin/chromeos-install
. "/usr/sbin/chromeos-common.sh" || exit 1
SRC=$(get_block_dev_from_partition_dev $(rootdev -s))
if [ "$(cat /sys/block/${SRC#/dev/}/removable)" == "1" ]; then
  REMOVABLE=1
fi

if [ "$(echo "$@" | grep -- "--usb")" -o "$REMOVABLE" = "1" ]; then
  . "$(dirname "$0")/crosh-usb"
fi

# Force dev behavior on dev images.
/usr/bin/crossystem "cros_debug?1"
DEVMODE=$((!$?))

if [ "$(echo "$@" | grep -- "--dev")" -o "$DEVMODE" = "1" ]; then
  . "$(dirname "$0")/crosh-dev"
fi

if [ -e "$(dirname $0)/crosh-workarounds" ]; then
  . "$(dirname "$0")/crosh-workarounds"
fi

ctrl_c() {
  return
}

trap ctrl_c INT

shell_read() {
  local prompt="$1"
  shift

  if [ "$IS_BASH" -eq "1" ]; then
    # In bash, -e gives readline support.
    read -p "$prompt" -e $@
  else
    read -p "$prompt" $@
  fi
}

shell_history() {
  if [ "$IS_BASH" -eq "1" ]; then
    # In bash, the history builtin can be used to manage readline history
    history $@
  fi
}

cmd_help() {
  echo "$HELP"
}

cmd_help_advanced() {
  echo "$HELP_ADVANCED"
}

cmd_exit() {
  exit
}

check_dforward() {
  # Matches a port number between 8000 and 8999.
  expr "$1" : '^8[0-9][0-9][0-9]$' > /dev/null
}

check_forward() {
  # Matches three things, separated by ':':
  # A port number, between 8000 and 8999;
  # A hostname
  # A port number, unrestricted
  expr "$1" : '^8[0-9][0-9][0-9]:[[:alnum:]][-[:alnum:].]*:[1-9][0-9]*$' \
      > /dev/null
}

check_serveraliveinterval() {
  # Matches a number of seconds.
  expr "$1" : '^[0-9][0-9]*$' > /dev/null;
}

check_keyfile() {
  # Allow files in /home/chronos/user, /media. Note that we *do* allow .., so
  # this isn't actually a security barrier, just a molly-guard to keep users
  # from putting keys in insecure storage.
  if [ ! -f "$1" -a ! -f "$HOME/Downloads/$1" ]; then
    return 1;
  fi
  if [ ! -r "$1" -a ! -r "$HOME/Downloads/$1" ]; then
    return 1;
  fi
  (expr "$1" : "^$HOME" > /dev/null) || \
  (expr "$1" : '^/media/' > /dev/null) || \
  (expr "$1" : '^[^/]*$' > /dev/null)
}

check_ssh_host() {
  check_hostname "$1" || check_ipv6 "$1";
}

cmd_ssh() {
  local user=""
  local host=""
  local port="22"
  local idfile=""
  local dforwards=""
  local forwards=""
  local nocmd=""
  local serveraliveinterval=""
  local line
  local cmd
  local params
  local exit
  local id=$(uuidgen)

  local defopts="-e none -F /etc/ssh/ssh_config"

  if [ ! -z "$1" ]; then
    # Sets the username, host, and optionally port directly.  We accept:
    # 'user host', 'user host port', 'user@host', or 'user@host port'.
    local at_pos=$(expr index "$1" '@')
    if [ $at_pos = 0 ]; then
      user="$1"
      host="$2"
      if [ ! -z "$3" ]; then
        port="$3"
      fi
    else
      user=$(substr "$1" "0" $(expr "$at_pos" - 1))
      host=$(substr "$1" "$at_pos")
      if [ ! -z "$2" ]; then
        port="$2"
      fi
    fi
  fi

  if [ -z "$user" -o -z "$host" ]; then
    while [ 1 ]; do
      if ! shell_read "ssh> " line; then
        echo;
        exit=1;
        break
      fi

      local space_pos=$(expr index "$line" ' ')
      if [ $space_pos = 0 ]; then
        cmd="$line"
        params=""
      else
        cmd=$(substr "$line" "0" "$space_pos")
        params=$(substr "$line" "$space_pos")
      fi

      case "$cmd" in

      key)
        if check_keyfile "$params"; then
          mkdir -p -m 600 "$HOME/.ssh";
          trap "rm -f $HOME/.ssh/key-$id" EXIT;
          (cd "$HOME/Downloads" ; cp -- "$params" "$HOME/.ssh/key-$id")
          chmod 600 "$HOME/.ssh/key-$id"
          idfile="-i $HOME/.ssh/key-$id"
        else
          echo "File '$params' is not a valid key file. Key files must reside"
          echo "under /media or $HOME. Key files in the Downloads directory may"
          echo "be specified with an unqualified name."
        fi
        ;;

      dynamic-forward)
        if ! check_dforward "$params"; then
          echo "Invalid forward '$params'."
          echo "Note that the local port number must be in 8000-8999."
        else
          dforwards="$dforwards -D$params"
        fi
        ;;

      forward)
        if ! check_forward "$params"; then
          echo "Invalid forward '$params'"
          echo "Note that the local port number must be in 8000-8999."
        else
          forwards="$forwards -L$params"
        fi
        ;;

      nocmd)
        nocmd="-N"
        ;;

      server-alive-interval)
        if ! check_serveraliveinterval "$params"; then
          echo "Invalid ServerAliveInterval '$params'."
        else
          serveraliveinterval="-oServerAliveInterval=$params"
        fi
        ;;

      port)
        if ! check_digits "$params"; then
          echo "Invalid port '$params'"
        else
          port="$params"
        fi
        ;;

      user)
        user="$params"
        ;;

      host)
        host="$params"
        ;;

      exit)
        exit=1
        break
        ;;

      connect)
        break
        ;;

      *)
        echo "connect                       - connect"
        echo "dynamic-forward port          - dynamic socks proxy (-D)"
        echo "forward port:host:port        - static port forward (-L)"
        echo "help                          - this"
        echo "host <hostname>               - remote hostname"
        echo "key <file>                    - sets private key to use (-i)"
        echo "nocmd                         - don't execute command (-N)"
        echo "port <num>                    - port on remote host (-p)"
        echo "server-alive-interval <num>   - set ServerAliveInterval option"
        echo "exit                          - exit ssh subsystem"
        echo "user <username>               - username on remote host"
        echo "Note that this program can only bind local ports in the range"
        echo "8000-8999, inclusive."
        ;;
      esac
    done
  fi

  if [ -z "$exit" ]; then
    if [ -z "$user" ]; then
      echo "No username given."
    elif [ -z "$host" ]; then
      echo "No host given."
    elif ! check_username "$user"; then
      echo "Invalid username '$user'"
    elif ! check_ssh_host "$host"; then
      echo "Invalid hostname '$host'"
    else
      ssh $defopts $idfile $dforwards $forwards $nocmd $serveraliveinterval \
          -p "$port" -l "$user" "$host"
    fi
  fi

  if [ -n "$idfile" ]; then
    rm "$HOME/.ssh/key-$id";
    trap - EXIT;
  fi
}

cmd_ssh_forget_host() {
  local known_hosts="$(readlink -f $HOME/.ssh/known_hosts)"

  # Test that the known_hosts is a regular file and is not 0 length.
  if [ ! -f "$known_hosts" -o ! -s "$known_hosts" ]; then
    echo "No known hosts."
    return
  fi

  local count="$(cat "$known_hosts" | wc -l)"

  # Print an indexed list of the known hosts.
  echo "Known hosts:"
  awk '{ print " " NR ") " $1; }' "$known_hosts"

  local hostno

  while true; do
    LINE_=""
    shell_read "Please select a host to forget [1-$count]: " LINE_
    if [ -z "$LINE_" ]; then
      echo "Aborting."
      return
    fi

    # Extract the numbers from the user input.
    hostno="$(echo $LINE_ | sed 's/[^[:digit:]]*//g')"

    # If they typed a number...
    if [ -n "$hostno" ]; then
      # And it was in the proper range...
      if [ $hostno -gt 0 -a $hostno -le $count ]; then
        # Then we can stop asking for input.
        break
      fi
    fi

    echo "Invalid selection.  Please enter a number between 1 and $count."
  done

  local trimmed="$(awk -v I="$hostno" 'NR != I { print }' "$known_hosts")"
  echo "$trimmed" > "$known_hosts"
  chmod 644 "$known_hosts"
}

cmd_swap() {
  local swap_enable_file="/home/chronos/.swap_enabled"

  case "$1" in
  "enable")
    if [ -z "$2" ]; then
      # remove file in case root owns it
      rm -f $swap_enable_file
      touch $swap_enable_file
    elif ! echo "$2" | grep -q "^[0-9]*$"; then
      echo "$2 is not a valid integer literal"
      cmd_swap usage
      return 1
    elif [ "$2" -ne 500 -a \
           "$2" -ne 1000 -a \
           "$2" -ne 2000 -a \
           "$2" -ne 3000 -a \
           "$2" -ne 4500 -a \
           "$2" -ne 6000 ]; then
      echo "invalid size $2. Valid choices: 500, 1000, 2000, 3000, 4500 or 6000"
      cmd_swap usage
      return 1
    else
      # remove file in case root owns it
      rm -f $swap_enable_file
      echo "$2" >$swap_enable_file
    fi
    echo "Swap will be ON at next reboot."
    echo "You are turning on compressed swap, which is an experimental feature"
    echo "of Chrome OS.  System instability may result.  To turn it off, use"
    echo "the command \"swap disable\"."
    ;;
  "disable")
    rm -f $swap_enable_file
    echo "Swap will be OFF at next reboot."
    ;;
  "status")
    /sbin/swapon -s
    ;;
  *)
    echo "Usage: swap < status | enable [<optional swap size (MB)>] | disable >"
    return 1
    ;;
  esac
}

cmd_experimental_storage() {
  local enable=""
  if [ -z "$1" ]; then
    echo "Usage: experimental_storage < status | enable | disable >"
    return 1
  fi

  case "$1" in
    "status")
      ;;
    "enable")
      enable="true"
      ;;
    "disable")
      enable="false"
      ;;
    *)
      echo "Invalid parameter: $1"
      return 1
      ;;
  esac

  if [ -z "$enable" ]; then
    enable=$( dbus-send --system --type=method_call --print-reply \
        --dest=org.chromium.CrosDisks /org/chromium/CrosDisks \
        org.freedesktop.DBus.Properties.Get string:org.chromium.CrosDisks \
        string:ExperimentalFeaturesEnabled 2>/dev/null )
    if [ $? -eq 0 ]; then
      if echo "$enable" | grep -iqs "true"; then
        echo "Experimental storage features are currently enabled."
      else
        echo "Experimental storage features are currently disabled."
      fi
    else
      echo "Could not determine the status of experimental storage features."
    fi
  else
    if dbus-send --system --type=method_call --print-reply \
        --dest=org.chromium.CrosDisks /org/chromium/CrosDisks \
        org.freedesktop.DBus.Properties.Set \
        string:org.chromium.CrosDisks string:ExperimentalFeaturesEnabled \
        variant:boolean:${enable} >/dev/null 2>&1; then
      echo "Experimental storage features have been ${1}d."
    else
      echo "Could not $1 experimental storage features."
    fi
  fi
}

cmd_ff_debug(){
  /usr/bin/ff_debug "$@"
}

cmd_wpa_debug(){
  /usr/bin/wpa_debug "$@"
}

cmd_set_arpgw(){
  /usr/bin/set_arpgw "$@"
}

cmd_network_logging(){
  if [ -n "$1" ]; then
    case "$1" in
      "wifi")
        echo; /usr/bin/ff_debug service+wifi+inet+device+manager
        echo; /usr/bin/wpa_debug msgdump
        echo; /usr/bin/modem set-logging info
        ;;
      "cellular")
        echo; /usr/bin/ff_debug service+cellular+modem+device+manager
        echo; /usr/bin/wpa_debug info
        echo; /usr/bin/modem set-logging debug
        ;;
      "ethernet")
        echo; /usr/bin/ff_debug service+ethernet+device+manager
        echo; /usr/bin/wpa_debug info
        echo; /usr/bin/modem set-logging info
        ;;
      "--help")
        echo "Usage: network_logging <wifi | cellular | ethernet>"
        ;;
      *)
        echo "Invalid parameter $1"
        ;;
    esac
  else
    echo "Missing parameter wifi | cellular | ethernet"
  fi
}

cmd_network_diag(){
  /usr/bin/network_diagnostics "$@"
}

debugd() {
  method="$1"; shift
  dbus-send --system --print-reply --fixed --dest=org.chromium.debugd \
      /org/chromium/debugd "org.chromium.debugd.$method" "$@"
}

cmd_ping() {
  local option="dict:string:variant:"

  # NB: use printf to avoid echo interpreting -n
  while [ "$(printf '%s' "$1" | cut -c1)" = "-" ]; do
    # Do just enough parsing to filter/map options; we
    # depend on ping to handle final validation
    if [ "$1" = "-i" ]; then
      shift; option="${option}interval,int32:$1,"
    elif [ "$1" = "-c" ]; then
      shift; option="${option}count,int32:$1,"
    elif [ "$1" = "-W" ]; then
      shift; option="${option}waittime,int32:$1,"
    elif [ "$1" = "-s" ]; then
      shift; option="${option}packetsize,int32:$1,"
    elif [ "$1" = "-n" ]; then
      option="${option}numeric,boolean:true"
    else
      echo "Unknown option: $1"
      return 1
    fi

    shift
  done

  if [ -z "$1" ]; then
    echo "Missing parameter: destination"
    return 1
  fi

  local dest="$1"
  if [ "$dest" = "gw" ]; then
    # Convenient shorthand for the next-hop gateway attached
    # to the default route; this means if you have a host named
    # "gw" then you'll need to specify a FQDN or IP address.
    dest=$(/sbin/route -n | awk '$1 == "0.0.0.0" { print $2; }')
    if [ -z "$dest" ]; then
      echo "Cannot determine primary gateway; routing table is:"
      cmd_route -n
      return 1
    fi
  fi

  option=$(echo "$option" | sed 's/,$//')

  # We want C-c to terminate the running ping so that the UI stays the same.
  # Therefore, create a fifo to direct the output of the ping to, and have a
  # subshell read from the fifo and emit to stdout. When the subshell ends (at a
  # C-c), we stop the ping and clean up the fifo.
  # no way to mktemp a fifo, so make a dir to hold it instead
  dir=$(mktemp -d "/tmp/crosh-ping-XXXXXXXXXX")
  if [ $? -ne 0 ]; then
    echo "Can't create temporary directory"
    return 1
  fi
  fifo="${dir}/fifo"
  if ! mkfifo "$fifo"; then
    echo "Can't create fifo at $fifo"
    return 1
  fi
  debugd PingStart "fd:1" "string:$dest" "$option" 2>&1 > "$fifo" &
  read pid < "$fifo"
  echo "pid: $pid"
  (while read line; do echo "$line"; done) < "$fifo"
  debugd PingStop "string:$pid"
  if [ $? -ne 0 ]; then
    echo "Can't stop ping"
    return 1
  fi
  rm -rf "$dir"
}

# TODO(dkrahn): Remove once this is the default. crosbug.com/22543
cmd_chaps() {
  local flag_file="/home/chronos/.disable_chaps"
  local enabled=1
  local changed=0
  if [ -r ${flag_file} ]; then
    enabled=0
  fi
  if [ -z "$1" ]; then
    if [ ${enabled} -eq 1 ]; then
      echo "Currently enabled"
    else
      echo "Currently disabled"
    fi
    return
  fi
  if [ "$1" = "on" ]; then
    if [ $enabled -eq 0 ]; then
      changed=1;
    fi
    rm -f "${flag_file}"
  else
    if [ $enabled -eq 1 ]; then
      changed=1
    fi
    touch "${flag_file}"
  fi
  if [ $changed -eq 1 ]; then
    echo "You must reboot for this to take effect."
  else
    echo "No change."
  fi
}

cmd_chaps_debug() {
  local level=${1:--2}
  if [ "$1" = "stop" ]; then
    level=0
  fi
  if [ "$1" = "start" ]; then
    level=-2
  fi
  rm -f /home/chronos/.chaps_debug*
  if [ "${level}" = "-1" ]; then
    touch /home/chronos/.chaps_debug_1
  elif [ "${level}" = "-2" ]; then
    touch /home/chronos/.chaps_debug_2
  fi
  /usr/bin/chaps_client --set_log_level=${level} 2> /dev/null
  if [ $? -eq 0 ]; then
    echo "Logging level set to ${level}."
  else
    echo "Failed to set logging level."
  fi
}

cmd_route() {
  local option="dict:string:variant:"

  # NB: use printf to avoid echo interpreting -n
  while [ "$(printf '%s' "$1" | cut -c1)" = "-" ]; do
    if [ "$1" = "-n" ]; then
      option="${option}numeric,boolean:true,"
    elif [ "$1" = "-6" ]; then
      option="${option}v6,boolean:true,"
    else
      echo "Unknown option: $1"
      return 1
    fi

    shift
  done
  option=$(echo "$option" | sed 's/,$//')

  debugd GetRoutes "$option"
}

cmd_tracepath() {
  local option="dict:string:variant:"

  # NB: use printf to avoid echo interpreting -n
  while [ "$(printf '%s' "$1" | cut -c1)" = "-" ]; do
    if [ "$1" = "-n" ]; then
      option="${option}numeric,boolean:true,"
    else
      echo "Unknown option: $1"
      return 1
    fi

    shift
  done

  option=$(echo "$option" | sed 's/,$//')

  if [ -z "$1" ]; then
    echo "Missing parameter: destination"
    return 1
  fi

  # We want C-c to terminate the running tracepath so that the UI stays the same.
  # Therefore, create a fifo to direct the output of the tracepath to, and have a
  # subshell read from the fifo and emit to stdout. When the subshell ends (at a
  # C-c), we stop the tracepath and clean up the fifo.
  # TODO(ellyjones): factor this (and the similar code in cmd_ping) out somehow
  # no way to mktemp a fifo, so make a dir to hold it instead
  dir=$(mktemp -d "/tmp/crosh-tracepath-XXXXXXXXXX")
  if [ $? -ne 0 ]; then
    echo "Can't create temporary directory"
    return 1
  fi
  fifo="${dir}/fifo"
  if ! mkfifo "$fifo"; then
    echo "Can't create fifo at $fifo"
    return 1
  fi
  debugd TracePathStart "fd:1" "string:$1" "$option" 2>&1 > "$fifo" &
  read pid < "$fifo"
  echo "pid: $pid"
  (while read line; do echo "$line"; done) < "$fifo"
  debugd TracePathStop "string:$pid"
  if [ $? -ne 0 ]; then
    echo "Can't stop tracepath"
    return 1
  fi
  rm -rf "$dir"
}

cmd_top() {
  # -s is "secure" mode, which disables kill, renice, and change display/sleep
  # interval.
  top -s
}

cmd_modem() {
  /usr/bin/modem "$@"
}

cmd_modem_set_carrier() {
  /usr/bin/modem set-carrier "$@"
}

cmd_set_apn() {
  /usr/bin/set_apn "$@"
}

cmd_connectivity() {
  /usr/bin/connectivity "$@"
}

cmd_autest() {
  local omaha_url="autest"

  if [ "$1" = "-scheduled" ]; then
   # pretend that this is a scheduled check as opposed to an user-initiated
   # check for testing features that get enabled only on scheduled checks.
   omaha_url="autest-scheduled"
  fi

  echo "Calling update_engine_client with omaha_url = $omaha_url"
  /usr/bin/update_engine_client --omaha_url $omaha_url
}

cmd_tpcontrol() {
  /opt/google/touchpad/tpcontrol "$@"
}

cmd_try_touch_experiment() {
  # Test out a new set of Touch parameters briefly, then revert them.
  # This takes in a single string of hex digits ie ([a-fA-F0-9]*) that
  # correspond to an ascii string of the form
  # PARAMETER1 NAME:PARAMETER1 VALUE,PARAMETER2 NAME:PARAMETER2 VALUE,...
  # The input is encoded as hex to a) eliminate escaping issues for spaces
  # and b) obfuscate which properties are being changed from the user so they
  # don't see what they're changing, and have it influence their decision.

  # First, check and make sure only hex digit characters have been passed in
  if [ -n "`echo \"$@\" | sed 's/[0-9a-fA-F]//g'`" ]; then
    return 1
  fi

  # Converting the input from hex to ascii
  treatment="`echo \"$@\" | sed 's/\(..\)/\\\\u\1/g'`"
  treatment=`printf "${treatment}\n"`
  if [ -n "`echo \"${treatment}\" | sed 's/[0-9a-zA-Z :,\.\-]//g'`" ]; then
    return 1;
  fi

  # Get the current system setup and old values so we can restore them
  device=`/opt/google/touchpad/tpcontrol listdev`
  old_values="`xinput list-props ${device}`"

  # Splitting the treatment into property name/value pairs
  treatment_commands=""
  reset_commands=""
  IFS=,
  for pair in ${treatment}; do
    name="`echo "${pair}" | cut -d ":" -f1`"
    new_value="`echo "${pair}" | cut -d ":" -f2`"

    property_entry=`echo "${old_values}" | grep "${name}" | tr -d "\t"`
    property_number=`echo "${property_entry}" | sed "s/^.*(\([0-9]*\)).*$/\1/"`
    old_value=`echo "${property_entry}" | sed "s/^[^:]*:\(.*\)$/\1/"`

    change_cmd="${property_number}:${new_value}"
    reset_cmd="${property_number}:${old_value}"

    treatment_commands="${change_cmd},${treatment_commands}"
    reset_commands="${reset_cmd},${reset_commands}"
  done

  echo "Applying Changes now..."
  change_properties "${treatment_commands}", "${device}"

  echo "Press Ctrl+C to return to your original settings."
  cat

  echo "Reverting Changes now..."
  change_properties "${reset_commands}", "${device}"

  # Checking to make sure everything is back to normal
  restored_values="`xinput list-props ${device}`"
  if [ "${old_values}" != "${restored_values}" ]; then
    echo "ERROR: Some properties may not have been reset correctly!"
    echo "If your touchpad is misbehaving, you can restore it by logging out"
    echo "and back in again."
  fi
}

change_properties() {
  # change format: PROPERTY_NUMBER:PROPERTY_VALUE,...
  cleaned="`echo "$1" | sed "s/,*$//g"`"
  IFS=,
  for cmd in ${cleaned}; do
    property_number="`echo "${cmd}" | cut -d ":" -f1`"
    property_value="`echo "${cmd}" | cut -d ":" -f2`"
    xinput set-prop "$2" "${property_number}" "${property_value}"
  done
}

cmd_rlz() {
  local flag_file="$HOME/.rlz_disabled"
  local enabled=1
  local changed=0
  if [ -r "${flag_file}" ]; then
    enabled=0
  fi
  case "$1" in
    "status")
      if [ $enabled -eq 1 ]; then
        echo "Currently enabled"
      else
        echo "Currently disabled"
      fi
      return
      ;;

    "enable")
      if [ $enabled -eq 0 ]; then
        changed=1
      fi
      rm -f "${flag_file}"
      ;;

    "disable")
      if [ $enabled -eq 1 ]; then
        changed=1
      fi
      touch "${flag_file}"
      ;;

    *)
      echo "Usage: rlz < status | enable | disable >"
      return 1
      ;;
  esac
  if [ $changed -eq 1 ]; then
    echo "You must reboot for this to take effect."
  else
    echo "No change."
  fi
}

cmd_syslog() {
  logger -t crosh -- "$*"
}

substr() {
  local str="$1"
  local start="$2"
  local end="$3"

  if [ "$IS_BASH" = "1" ]; then
    # NB: use printf to avoid echo interpreting -n
    if [ -z "$end" ]; then
      printf '%s\n' ${str:$start}
    else
      printf '%s\n' ${str:$start:$end}
    fi
    return
  fi

  start=$(expr "$start" + 1)

  if [ ! -z "$end" ]; then
    end=$(expr "$end" - 1)
  fi

  echo "$str" | cut -c${start}-${end}
}

dispatch() {
  local line="$1"
  local command=""
  local params=""

  local space_pos=$(expr index "$line" ' ')

  if [ $space_pos = 0 ]; then
    command=$line
  else
    command=$(substr "$line" "0" "$space_pos")
    params=$(substr "$line" "$space_pos")
  fi

  if ! type "cmd_$command" 2>/dev/null | head -1 | grep -q "function"; then
    echo "Unknown command: '$command'"
  else
    command="cmd_$command"
    $command $params
  fi
}

# Checks that a given string looks like a hostname or IPv4 address (starts
# with an alphanumeric and contains only alphanumeric, '.', or '-'
# characters).
check_hostname() {
  expr "$1" : '^[[:alnum:]][-[:alnum:].]*$' > /dev/null
}

# Checks that a given string could plausibly be an IPv6 address
# (hexadecimal, ':', and '.' characters only, followed by an optional zone
# index consisting of a '%' and a device name).
check_ipv6() {
  echo "$1" | /bin/grep -E -q '^[0-9a-fA-F:.]+(%[a-z0-9]+)?$'
}

# Checks that a given string starts with an alphanumeric, and contains only
# alphanumeric and zero or more of "_:.~%$^\-"
check_username() {
  expr "$1" : '^[[:alnum:]][[:alnum:]_:.~%$^\-]*$' > /dev/null
}

check_digits() {
  expr "$1" : '^[[:digit:]]*$' > /dev/null
}

# Don't allow SIGHUP to terminate crosh. This guarantees that even if the user
# closes the crosh window, we make our way back up to the main loop, which gives
# cleanup code in command handlers a chance to run.
trap '' HUP

repl() {
  echo "Welcome to crosh, type 'help' for a list of commands."
  if [ "$IS_BASH" != "1" ]; then
    echo "Sorry, line editing and command history disabled due to" \
      "shell limitations."
  fi

  while [ 1 ]; do
    if shell_read "crosh> " LINE_; then
      if [ ! -z "$LINE_" ]; then
        shell_history -s "$LINE_"
        dispatch "$LINE_"
      fi
    else
      echo
      return 1
    fi
  done
}

INPUTRC="$(dirname "$0")/inputrc.crosh"
HISTFILE="$HOME/.crosh_history"
shell_history -r $HISTFILE

# Initialize pseudo completion support.
if [ "$IS_BASH" = "1" ]; then
  bind 'TAB:dynamic-complete-history' 2>/dev/null
  for f in $(declare -F | sed -n '/-f cmd_/s:.*cmd_::p'); do
    # Do not add duplicates to avoid ballooning history.
    grep -qs "^${f}$" $HISTFILE || shell_history -s $f
  done
fi

repl

shell_history -w $HISTFILE