Git post-commit hook to check C/C++ source file format using astyle (Artistic Style) + automatic creation of a commit with a fix

githook-astyle.sh

#!/bin/bash
# Installation:
#   cd my_gitproject
#   wget -O pre-commit.sh http://tinyurl.com/mkovs45
#   ln -s ../../pre-commit.sh .git/hooks/pre-commit
#   chmod +x pre-commit.sh

function have_uncommitted()
{
    lines=$(git diff --name-only | wc -l)

    if [ 0 -ne $lines ]; then
        git stash > /dev/null
        echo 1
    else
        echo 0
    fi
}

OPTIONS="--style=k&r --brackets=linux --indent-preprocessor --break-blocks --pad-oper --pad-header --unpad-paren --align-pointer=name --convert-tabs"

astyle_commit=0
RETURN=0
ASTYLE=$(which astyle)
exec < /dev/tty
if [ $? -ne 0 ]; then
    echo "[!] astyle not installed. Unable to check source file format policy." >&2
    exit 1
fi

stashed=$(have_uncommitted)
# get all changed files in last commit
FILES=$(git diff --name-only HEAD~1 | grep -E "\.(c|cpp|h)$")
# clear stash when we used him
if [ $stashed -eq 1 ]; then
    git stash pop
fi

for FILE in $FILES; do
    $ASTYLE $OPTIONS < $FILE | cmp -s $FILE -
    if [ $? -ne 0 ]; then
        echo "[!] $FILE does not respect the agreed coding style." >&2
        RETURN=1
        # wait for user input to auto clean file
        echo "Should it be cleaned? [y/n] (All other changes will be stashed)"
        read clean_file
        if [[ $clean_file == "y" ]]; then
            echo "cleaning file $FILE"
            stashed=$(have_uncommitted)
            $ASTYLE $OPTIONS $FILE
            git add -u
            if [ $astyle_commit -eq 0 ]; then
                astyle_commit=1
                git commit -m "cleanup with astyle"
            else
                #there is already a commit with cleanup so use the same one
                git commit --amend
            fi
            ## replay changes
            # pop all changes which were staged before
            if [ $stashed -eq 1 ]; then
                git stash pop
            fi
            RETURN=0
        fi
    fi
done

if [ $RETURN -eq 1 ]; then
    echo "" >&2
    echo "Make sure you have run astyle with the following options:" >&2
    echo "astyle $OPTIONS" >&2
fi

exit $RETURN