git_crypt_filter

#!/bin/sh
# Copyright 2013, Ryan Feng
# This file is released under BSD 3-Clause license, please read LICENSE file for more details.

SALT=`git config --get encrypt.salt`
PASS=`git config --get encrypt.pass`

PATTERN_FILE=`git config --get encrypt.patternFile`
NAME_MATCHED=0

getSaltPass(){
    if [ -z "$SALT" -o -z "$PASS" ];then
        SALT=`getpwd git_crypt_salt`
        PASS=`getpwd git_crypt_pass`
    fi
}

match_pattern(){
    if [ -r "$PATTERN_FILE" ];then
        `fnmatch "$_GIT_FILENAME" "$PATTERN_FILE"`
        r=$?
        if [ -n "$_GIT_FILENAME" -a $r -eq 0 ];then
            NAME_MATCHED=1
        fi
    fi
}

check_fnmatch(){
    if [ ! -x `which fnmatch` ];then
        echo "Cannot find script fnmatch or it's not executable, using default filter..." > /dev/stderr
        return 1
    fi
}

encrypt(){
    openssl enc -base64 -aes-256-ecb -S "$SALT" -k "$PASS"
}

decrypt(){
    openssl enc -d -base64 -aes-256-ecb -k "$PASS" 2>/dev/null || cat
}

clean_filter(){
    if [ $NAME_MATCHED -eq 1 ];then
        encrypt
    else
        cat
    fi
}

smudge_filter(){
    if [ $NAME_MATCHED -eq 1 ];then
        decrypt
    else
        cat
    fi
}

diff_filter(){
    if [ $NAME_MATCHED -eq 1 ];then
        openssl enc -d base64 -aes-256-ecb -k "$PASS" -in "$1" 2>/dev/null || cat "$1"
    else
        cat "$1"
    fi
}

main(){
    check_fnmatch
    getSaltPass
    match_pattern
    cmd=$1
    shift 1
    case $cmd in
        smudge) smudge_filter $@;;
          diff) diff_filter $@;;
         clean) clean_filter $@;;
       encrypt) encrypt;;
       decrypt) decrypt;;
             *) echo "Unknown command $cmd, not using filter" > /dev/stderr;;
    esac
}

# Main procedure
main $@