conpile

#!/usr/bin/env bash

if (( UID != 0 )); then
    echo >&2 "E: you must be root in order to run this script."
    exit 1
fi

usage() {
    cat <<EOF
USAGE: ${0##*/} [-a | -i | -n] [-d DEBIAN_DIR]
    OPTIONS:
        -a: install already installed packages only (default)
        -i: install all non-debug packages plus already installed debug ones
        -n: don't install anything
        -d DEBIAN_DIR:
          specify an alternative debian/ directory. It will be copied
          to the current directory and the copy will be removed after build.
          If './debian' already exists, it will be renamed to './debian.old'
          (and renamed back after removing the copy). If it already exists too,
          you will be asked to resolve that manually.
EOF
    exit 2
}

DEBIAN_DIR=
INSTALL_POLICY=a
while getopts 'aind:' option; do
    case "$option" in
        [ain]) INSTALL_POLICY=$option ;;
        d) DEBIAN_DIR=$OPTARG ;;
        *) usage ;;
    esac
done
shift "$(( OPTIND - 1 ))" || usage
if (( $# != 0 )); then
    echo >&2 "E: unexpected positional argument."
    usage
fi

is_installed() {
    dpkg-query -s -- "$1" 2>/dev/null | grep -q '^Status: .* installed$'
}
case "$INSTALL_POLICY" in
    a)
        should_be_installed() {
            is_installed "$1"
        }
        ;;
    i)
        should_be_installed() {
            [[ $1 != *-dbg ]] || is_installed "$1"
        }
        ;;
    n)
        should_be_installed() {
            false
        }
        ;;
    *)
        echo >&2 "E: unknown INSTALL_POLICY: '$INSTALL_POLICY'. This is a bug, exiting."
        exit 2
        ;;
esac

copy_debian_dir_if_needed() {
    if [[ -z $DEBIAN_DIR ]]; then
        return
    fi
    if [[ -e debian ]]; then
        if [[ -e debian.old ]]; then
            echo >&2 "E: 'debian.old' already exists, resolve this manually."
            return 1
        fi
        mv debian debian.old || return "$?"
    fi
    cp -r -- "$DEBIAN_DIR" debian || return "$?"
}

remove_debian_dir_if_needed() {
    if [[ -z $DEBIAN_DIR ]]; then
        return
    fi
    rm -r --one-file-system debian
    if [[ -e debian.old ]]; then
        mv debian.old debian || return "$?"
    fi
}

compile_and_install() {
    if ! [[ -d debian ]]; then
        echo >&2 "E: ./debian/ does not exists."
        return 1
    fi
    mk-build-deps --install debian/control || return "$?"
    dpkg-buildpackage -b -uc -us || return "$?"
    local -a debs_to_install=()
    while IFS= read -r line; do
        local debfile=${line%% *}
        local pkg=${debfile%%_*}
        if should_be_installed "$pkg"; then
            debs_to_install+=(../"$debfile")
        fi
        local changesfile=${debfile%.deb}.changes
        if [[ -e ../$changesfile ]]; then
            rm ../"$changesfile" || true
        fi
    done < debian/files || return "$?"
    if (( ${#debs_to_install[@]} )); then
        install-deb "${debs_to_install[@]}" || return "$?"
    fi
}

copy_debian_dir_if_needed || exit "$?"
failed=0
if ! compile_and_install; then
    echo >&2 "*** E: compile_and_install failed, now cleaning up (if needed) and exiting."
    failed=1
fi
remove_debian_dir_if_needed || exit "$?"
if (( failed )); then
    echo >&2 "*** E: now exiting (see above)."
    exit 1
fi