function computer.getBootAddress()
 return component.invoke(component.list("eeprom")(),"getData")
end
function computer.setBootAddress(a)
 return component.invoke(component.list("eeprom")(),"setData",a)
end
return (function()
local rv
local function getProxy(addr)
 if type(addr) == "string" then
  return component.proxy(addr)
 end
 return addr
end

local eformat = "c20c4>I4>I4"
function parsePartitions(s)
 local rt = {}
 for i = 1, s:len(), 32 do
  local n, t, start, length = string.unpack(eformat, s, i)
  n = n:gsub("\0", "")
  if n ~= "" then
   rt[#rt+1] = {n,t,start,length}
  end
 end
 return rt
end

function getPartitions(drive)
 return parsePartitions(drive.readSector(drive.getCapacity() / drive.getSectorSize()))
end

local function offsetSector(part,sector)
 if sector < 1 or sector > part[4] then error("invalid offset, not in a usable sector") end
 return (part[3] - 1) + sector
end
local function readSector(drive,part,sector)
 return drive.readSector(offsetSector(part,sector)):gsub("\0+$","")
end
local function readPart(drive,part)
 local rv = ""
 for i = 1, part[4] do
  rv=rv .. readSector(drive,part,i)
 end
 return rv
end

local candidates={computer.getBootAddress()}
for a,_ in component.list("drive") do
 candidates[#candidates+1] = a
end
for i,a in ipairs(candidates) do
 computer.beep(("."):rep(i))
 local d = getProxy(a)
 if type(d) == "table" then
  for k,v in ipairs(getPartitions(d)) do
   if v[2] == "boot" then
    local rv = load(readPart(d,v))
    if rv then
     computer.beep("-")
     computer.setBootAddress(a)
     return rv
    end
   end
  end
 end
end
end)()()