Mag Card Writer

arguments = { ... }
if #arguments == 0 then
 print("Usage: writeCode <path to code> [card label]")
 error()
end
if not fs.exists(arguments[1]) then
 print("Error: file not found")
 error()
end
if fs.isDir(arguments[1]) then
 print("Error: directory given")
 error()
end
code = {}
file = fs.open(arguments[1], "rb")
while true do
 local byte = file.read()
 if not byte then break end
 table.insert(code, string.char(byte))
end
code = table.concat(code)
if code:len() > 100 then
 print("Error: code length exceeds 100 bytes")
 error()
end

function constructLabel()
 label = ""
 for n = 2, #arguments do
  label = label .. arguments[n]
  if n < #arguments then label = label .. " " end
 end
 return label
end

cardLabel = constructLabel()
if cardLabel == "" then cardLabel = "No Label Given" end

local side = nil;
for _,side1 in ipairs(rs.getSides()) do
    if peripheral.getType(side1)=='mag card reader' then
        side = side1
    end
end

if not side then
    print("Error: No mag-card writer found")
    error()
end

peripheral.call(side, "beginWrite", code, cardLabel)
while true do
 event = os.pullEvent("mag_write_done")
 if event == "mag_write_done" then
  print("Successfully wrote code to magCard")
  break
 end
end