#!/bin/sh
#
# gitenealogy - Trace the ancestry of a file in git across renames
#
# Written 2010 by Werner Almesberger
# Copyright 2010 Werner Almesberger
#
# 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 2 of the License, or
# (at your option) any later version.
#


usage()
{
    cat <<EOF 2>&1
usage: $0 repo-dir path

  The file to trace must be at repo-dir/path
EOF
    exit 1
}


if [ -z "$2" -o ! -z "$3" ]; then
    usage
fi

if [ ! -d "$1" -o ! -d "$1/.git" ]; then
    echo "no git repository at $1" 1>&2
    exit 1
fi
if [ ! -f "$1/$2" ]; then
    echo "cannot find $2" 2>&1
    exit 1
fi

cd "$1" || exit
git log --follow --name-status -- "$2" |
    awk '
/^commit /{ if (c) print c, n; c = $2 }
{ if (NF) n = $(NF) }
END { if (c) print c, n; }'