#!/bin/bash

function patch_strings_in_file()

{

    local FILE="$1"

    local PATTERN="$2"

    local REPLACEMENT="$3"

    # Find all unique strings in FILE that contain the pattern

    STRINGS=$(strings ${FILE} | grep ${PATTERN} | sort -u -r)

    if [ "${STRINGS}" != "" ] ; then

        echo "File '${FILE}' contain strings with '${PATTERN}' in them:"

        for OLD_STRING in ${STRINGS} ; do

            # Create the new string with a simple bash-replacement

            NEW_STRING=${OLD_STRING//${PATTERN}/${REPLACEMENT}}

            # Create null terminated ASCII HEX representations of the strings

            OLD_STRING_HEX="$(echo -n ${OLD_STRING} | xxd -g 0 -u -ps -c 256)00"

            NEW_STRING_HEX="$(echo -n ${NEW_STRING} | xxd -g 0 -u -ps -c 256)00"

            if [ ${#NEW_STRING_HEX} -le ${#OLD_STRING_HEX} ] ; then

                # Pad the replacement string with null terminations so the

                # length matches the original string

                while [ ${#NEW_STRING_HEX} -lt ${#OLD_STRING_HEX} ] ; do

                    NEW_STRING_HEX="${NEW_STRING_HEX}00"

                done

                # Now, replace every occurrence of OLD_STRING with NEW_STRING

                echo -n "Replacing ${OLD_STRING} with ${NEW_STRING}... "

                hexdump -ve '1/1 "%.2X"' ${FILE} | \

                sed "s/${OLD_STRING_HEX}/${NEW_STRING_HEX}/g" | \

                xxd -r -p > ${FILE}.tmp

                chmod --reference ${FILE} ${FILE}.tmp

                mv ${FILE}.tmp ${FILE}

                echo "Done!"

            else

                echo "New string '${NEW_STRING}' is longer than old" \

                     "string '${OLD_STRING}'. Skipping."

            fi

        done

    fi

}

patch_strings_in_file $@