ComputerCraft Universal File Handle (Broken)

function UniversalHandle( filename, binary )
    local proxy, readHandle, writeHandle, seekWhence, seekOffset, vBufMode, vBufSize, contents, activeHandle = {}

    local function readSetup()
        if io.type(readHandle) ~= "file" then
            if io.type(writeHandle) == "file" then
                writeHandle:close()
            end

            readHandle = io.open(filename, binary and "rb" or "r")
            activeHandle = readHandle
        end

        readHandle:seek(seekWhence, seekOffset)
    end

    local function read( self, ... )
        readSetup()
        return binary and readHandle:read() or readHandle:read(...)
    end

    local function lines( self, ... )
        readSetup()
        return binary and function() return read() end or readHandle:lines(...)
    end

    local function close()
        if io.type(readHandle) == "file" then
            readHandle:close()
        end

        if io.type(writeHandle) == "file" then
            writeHandle:close()
        end
    end

    local function seek( self, whence, offset )
        seekWhence = whence
        seekOffset = offset

        return activeHandle:seek(whence, offset)
    end

    local function flush()
        if io.type(writeHandle) == "file" then
            writeHandle:flush()
        end
    end

    local function setvbuf( self, mode, size )
        vBufMode = mode
        vBufSize = size
    end

    local function write( self, ... )
        readSetup()
        readHandle:seek("set")
        contents = read("*a")
        readHandle:close()



        writeHandle = io.open(filename, binary and "wb" or "w")
        activeHandle = writeHandle

        if binary then
            local len = #contents
            contents = string.byte(contents, 1, len)
            for i=1, len do
                writeHandle:write(contents[i])
            end
        else
            writeHandle:write(contents)
        end

        writeHandle:seek(seekWhence, seekOffset)
        writeHandle:setvbuf(vBufMode, vBufSize)

        writeHandle:write(...)
    end

    local proxy = {read = read, lines = lines, close = close, seek = seek, flush = flush, setvbuf = setvbuf, write = write}

    return proxy
end