askpass

#!/bin/sh -eu

# askpass: configure or query askpass helper
# Copyright (C) 2018  "Michael G. Morey" <mgmorey@gmail.com>

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

abort() {
    printf "$@" >&2
    exit 1
}

assert() {
    "$@" || abort '%s: Assertion failed: %s\n' "$script" "$*"
}

parse_arguments() {
    is_query=false
    shell=$SHELL

    while getopts s:qh opt; do
	case $opt in
	    (s)
		shell=$OPTARG
		;;
	    (q)
		is_query=true
		;;
	    (h)
		usage
		exit 0
		;;
	    (\?)
		exit 2
		;;
	esac
    done

    shift $(($OPTIND - 1))

    if [ $is_query = true -a $# -gt 0 ]; then
	usage_error '%s: Too many arguments\n' "$script"
    elif [ $# -gt 0 ]; then
	commands="$*"
    else
	commands="git ssh sudo"
    fi
}

usage() {
    cat <<EOF >&2
Usage: $script [-s SHELL] [COMMAND [COMMAND] ...]
       $script -q
       $script -h
EOF
}

usage_error() {
    if [ $# -gt 0 ]; then
	printf "$@" >&2
    fi

    printf '%s\n' '' >&2
    usage
    exit 2
}

script=$(basename "$0")

case "$0" in
    (*/*)
	script_dir=$(cd "$(dirname "$0")" && pwd)
	;;
    (*)
	script_dir=
	;;
esac

script_prefix=${script_dir:+$script_dir/}

parse_arguments "$@"

if [ $is_query = true ]; then
    "${script_prefix}get-askpass-helper"
else
    "${script_prefix}set-askpass-parameters" -s $shell ${commands-}
fi