Keyscript for cryptsetup

cat_or_askpass

#!/bin/sh

timeout=30
counter=0
keyfile="$1"

echo_error() {
    echo $@ >&2
}

password_fallback() {
    echo_error "Falling back to password entry."
    /lib/cryptsetup/askpass "Enter password for ${CRYPTTAB_NAME}: "
}

if [ -z "$keyfile" ]; then
    echo_error "Keyfile argument not provided."
    password_fallback
    exit $?
fi

while [ ! -e "$keyfile" ] && [ $counter -lt $timeout ]; do
    counter=$(($counter + 1))
    sleep 1
done

keyfile=$(readlink -f "$keyfile")
if [ ! -e "$keyfile" ]; then
    echo_error "Keyfile unavailable."
    password_fallback
elif [ ! -r "$keyfile" ]; then
    echo_error "Keyfile is not readable."
    password_fallback
elif [ -d "$keyfile" ]; then
    echo_error "Keyfile is a directory."
    password_fallback
elif [ -b "$keyfile" ]; then
    cat "$keyfile"
elif [ ! -s "$keyfile" ]; then
    echo_error "Keyfile is empty."
    password_fallback
else
    cat "$keyfile"
fi