buildtool/linux/tools/x86_64-linux-gnu/sysroot/lib/cryptsetup/scripts/decrypt_gnupg-sc

#!/bin/sh

if [ -d "/cryptroot/gnupghome" ]; then
    export GNUPGHOME="/cryptroot/gnupghome"
fi

run_gpg() {
    gpg --no-options --trust-model=always "$@"
}
decrypt_gpg () {
    local console _
    if ! GPG_TTY="$(tty)"; then
        read console _ </proc/consoles
        GPG_TTY="/dev/$console"
    fi
    export GPG_TTY

    if ! run_gpg --decrypt -- "$1"; then
        return 1
    fi
    return 0
}

# `gpg-connect-agent LEARN /bye` is another (lighter) way, but it's
# harder to retrieve the return code
if ! run_gpg --batch --quiet --no-tty --card-status >/dev/null; then
    echo "Please insert OpenPGP SmartCard..." >&2
    until run_gpg --batch --quiet --no-tty --card-status; do
        sleep 1
    done >/dev/null 2>&1
fi

if [ ! -x /usr/bin/gpg ]; then
    echo "$0: /usr/bin/gpg is not available" >&2
    exit 1
fi

if [ -z "$1" ] || [ ! -f "$1" ]; then
    echo "$0: missing key as argument" >&2
    exit 1
fi

decrypt_gpg "$1"
exit $?