usage: invoker <function [arguments] >
        unpackbootimg    unpack android boot.img
        mkbootimg        make android boot.img
        split_app        split huawei .app file
        sdat2img         convert andorid dat file to raw image
        simg2img         convert sparse image to raw image
        img2simg         convert raw image to sparse image
        minigzip         gzip archives operating functions
        envalid          change file permission to 0755
        uncpio           extract cpio archives
        mkcpio           make cpio archives
        dd               minimal dd function