# -*-shell-script-*-
# This should be sourced by bash (though we welcome changes to make it POSIX sh compliant)

# Monkeysphere gen-subkey subcommand
#
# The monkeysphere scripts are written by:
# Jameson Rollins <jrollins@finestructure.net>
# Jamie McClelland <jm@mayfirst.org>
# Daniel Kahn Gillmor <dkg@fifthhorseman.net>
#
# They are Copyright 2008-2009, and are all released under the GPL,
# version 3 or later.

# generate a subkey with the 'a' usage flags set

gen_subkey(){
    local keyLength
    local gpgSecOut
    local keyID
    local editCommands
    local fifoDir

    # get options
    while true ; do
	case "$1" in
	    -l|--length)
		keyLength="$2"
		shift 2
		;;
	    *)
		if [ "$(echo "$1" | cut -c 1)" = '-' ] ; then
		    failure "Unknown option '$1'.
Type '$PGRM help' for usage."
		fi
		break
		;;
	esac
    done

    # check that the keyID is unique
    keyID=$(check_gpg_sec_key_id "$@")

    # check that an authentication subkey does not already exist
    check_gpg_authentication_subkey "$keyID"

    # generate the list of commands that will be passed to edit-key
    editCommands=$(cat <<EOF
addkey
7
S
E
A
Q
$keyLength
0
save
EOF
)

    # setup the temp fifo dir for retrieving the key password
    log debug "creating password fifo..."
    fifoDir=$(msmktempdir)
    trap "rm -rf $fifoDir" EXIT
    (umask 077 && mkfifo "$fifoDir/pass")

    log verbose "generating subkey..."
    echo "$editCommands" | gpg --passphrase-fd 3 3< "$fifoDir/pass" --expert --command-fd 0 --edit-key "$keyID" &

    # FIXME: this needs to fail more gracefully if the passphrase is incorrect
    passphrase_prompt  "Please enter your passphrase for $keyID: " "$fifoDir/pass"

    trap - EXIT
    rm -rf "$fifoDir"
    wait
    log verbose "done."
}