git-fix-whitespace

#!/bin/bash

me="$(basename $0)"

usage() {
    cat << EOF
git-fix-whitespace - Fixes the whitespace issues that 'git-diff --check'
                     complains about.

Usage:
    $me --cached
    $me tree-ish tree-ish

Synopsis:
    In its first form the index is modified to correct the whitespace issues
    found in the files added to the index.

    In its second form the index is modified to correct the whitespace issues
    found in the files that changed between the 2 hashes given.

Notes:
  1. In git terminology "tree-sh" refers to anything that can be resolved to a
     tree, including a hash, tag, branch, or something like HEAD~3 (meaning 3
     commits prior to HEAD).

  2. This script does not use perl/awk/sed/etc. to do is modifications. It uses
     git's own functionality. For this reason it should be very future-proof.

Acknowledgments:
    Copyright (c) 2010 Richard Bronosky
    Offered under the terms of the MIT License.
    http://www.opensource.org/licenses/mit-license.php
    Created while employed by CMGdigital
EOF
exit
}

apply_fail(){
    echo "Failed to apply patch $PATCH"
    echo
    echo "Perhaps you tried to do a hash comparison with uncommitted changes in your"
    echo "working tree."
    exit $1
}

err_files(){
    git diff $ARG1 $ARG2 --check | sed -E '/^(\+|-)/d;s/:.*//' | sort | uniq
}

case "$#" in
    1)
        test "$1" = "--cached" && ARG1=$1 || {
            echo
            echo "Inavlid arguments"
            echo
            echo
            usage
        }
        ARG1=$1
        ARG2=HEAD
        ;;
    2)
        ARG1=$1
        ARG2=$2
        ;;
    *)
        test $# > 3 && {
            echo
            echo "Invalid arguments"
            echo
            echo
        }
        usage
        ;;
esac

PATCH=$(mktemp -p $(pwd -P) ${me}.patch.XXXXXX)
git diff $ARG1 $ARG2 > $PATCH
FILES=$(sed '/^+++ /!d;s?^+++ b/??' $PATCH)
echo -e "Files in index with whitespace errors:\n$(err_files 1)"
git apply --whitespace=fix -R $PATCH || apply_fail 1
git apply --whitespace=fix $PATCH || apply_fail 2
git reset HEAD $FILES
git add $FILES
rm $PATCH
if [[ $(err_files 2 | wc -l) -gt 0 ]]; then
    echo -e "Remaining files in index with whitespace errors:\n$(err_files 3)"
fi