#!/usr/local/bin/lua51

-----------------------------------------------------------------------
-- Checking arguments
-----------------------------------------------------------------------

progname = "mbrsign"

if arg[1] == nil then
	print("usage: " .. progname .. " file")
	os.exit(1)
end

local function perror(msg)
	print(progname .. ": " .. msg)
	os.exit(1)
end

local file = io.open(arg[1], "rb")

if file == nil then
	perror("failed to open file " .. arg[1])
end


-----------------------------------------------------------------------
-- Check file size
-----------------------------------------------------------------------
local size = file:seek("end")

if size > 512 then
	perror("boot file " .. arg[1] .. " size is more than 512 bytes : " .. size .. " bytes")
end

file:close()

-----------------------------------------------------------------------
-- Filling 0s
-----------------------------------------------------------------------
file = io.open(arg[1], "r+")

if file == nil then
	perror("faile to open file " .. arg[1] .. " for writting")
end

if size < 512 then
	file:seek("set", size)
	for i = size, 509 do
		file:write(string.char(0))
	end
end

file:seek("set", 510)
file:write(string.char("0x55"))
file:write(string.char("0xaa"))

file:close()