diff-shared-git-repo-files.sh

#!/usr/bin/env bash
# vim: filetype=sh

REPO_1="$(readlink -f "${1:-$(pwd)}")"
REPO_2="$(readlink -f "$2")"

quit() {
    echo "quit_with_error()"
    echo "ERROR: $@" >&2
    exit 1
}

dump_git_files() {
    cd "$1"
    local GIT_FILE_LIST="$(mktemp)"
    git ls-files > "$GIT_FILE_LIST"
    echo "$GIT_FILE_LIST"
}

check_git_repo_path() {
    cd "$1" 2>/dev/null || {
        quit "'$1' directory does not exist!"
    }
    git rev-parse --git-dir &>/dev/null || {
        quit "'$1' is not a Git repository!"
    }
}

diff_repo_files() {
    check_git_repo_path "$1"
    check_git_repo_path "$2"

    local REPO_1_FILE_LIST="$(dump_git_files "$1")"
    local REPO_2_FILE_LIST="$(dump_git_files "$2")"

    comm -12 "$REPO_1_FILE_LIST" "$REPO_2_FILE_LIST" | while read REPO_FILE ; do
        if ! cmp -s "$REPO_1/$REPO_FILE" "$REPO_2/$REPO_FILE" ; then
            echo "$REPO_FILE"
        fi
    done

    rm "$REPO_1_FILE_LIST"
    rm "$REPO_2_FILE_LIST"
}


if [[ -z "$REPO_1" || -z "$REPO_2" ]] ; then
    quit 'Missing argument!'
fi

diff_repo_files "$REPO_1" "$REPO_2"