git-vdiff.sh

#!/bin/bash

set -euo pipefail

commit=$1
parent=$1^1

function commit_path_sha512 {
    git cat-file blob $(git rev-parse $1:$2) | sha512sum | cut -d " " -f 1
}

function diff_path { echo ${1:6}; }

function diff_a { expr match "$1" '^--- a/' >/dev/null; }
function diff_b { expr match "$1" '^+++ b/' >/dev/null; }

function v_improve {
    while read line; do
        if   diff_a "$line"; then
            local path=$(diff_path "$line")
            local sha512=$(commit_path_sha512 "$parent" "$path")
            echo "$line $sha512"
        elif diff_b "$line"; then
            local path=$(diff_path "$line")
            local sha512=$(commit_path_sha512 "$commit" "$path")
            echo "$line $sha512"
        else
            echo "$line"
        fi
    done
}

git diff $parent..$commit | v_improve