#!/bin/sh
###############################################################################
# BRLTTY - A background process providing access to the console screen (when in
#          text mode) for a blind person using a refreshable braille display.
#
# Copyright (C) 1995-2021 by The BRLTTY Developers.
#
# BRLTTY comes with ABSOLUTELY NO WARRANTY.
#
# This is free software, placed under the terms of the
# GNU Lesser General Public License, as published by the Free Software
# Foundation; either version 2.1 of the License, or (at your option) any
# later version. Please see the file LICENSE-LGPL for details.
#
# Web Page: http://brltty.app/
#
# This software is maintained by Dave Mielke <dave@mielke.cc>.
###############################################################################

set -e
umask 077

. "`dirname "${0}"`/brltty-prologue.sh"
. "${programDirectory}/brltty-config.sh"

defaultKeyFile="${BRLTTY_EXECUTE_ROOT}${BRLAPI_KEY_FILE}"

addProgramOption f string.path keyFile "the BrlAPI key file" "${defaultKeyFile}"
parseProgramArguments "${@}"

try() {
   ("${@}"; exit "${?}") 2>/dev/null && {
      logMessage task "key generated"
      exit 0
   }
}

[ -n "${keyFile}" ] || keyFile="${defaultKeyFile}"

logMessage step "trying mcookie"
try mcookie >"${keyFile}"

for device in "/dev/urandom" "/dev/random"
do
   [ -c "${device}" -a -r "${device}" ] && {
      logMessage step "trying ${device}"
      try dd if="${device}" of="${keyFile}" bs=32 count=1
   }
done

logMessage step "trying \$RANDOM"
key="${RANDOM}"
[ -n "${key}" ] && try echo >"${keyFile}" "${key}"

rm -f -- "${keyFile}"
semanticError "no supported mechanism is available"
exit 3