Motorola unpack radio.img / gpt.bin / "SINGLE_N_LONELY" layout files

#!/usr/bin/env lua5.3
-- parse files (ex. img and bin) with magic SINGLE_N_LONELY
-- works on various Motorola devices

-- Can use on Windows with: https://sourceforge.net/projects/luabinaries/files/5.4.2/Tools%20Executables/lua-5.4.2_Win64_bin.zip/download​​​
-- Some use cases: https://forum.xda-developers.com/t/rom-official-lineageos-20-android-13-for-the-motorola-edge-30-dubai.4536169/page-7 and from script author: https://forum.xda-developers.com/t/edl-mode-and-test-point-of-the-moto-g-5g-plus.4371213/page-2#post-87931915

function abort(msg)
  io.stderr:write(msg .. "\n")
  os.exit()
end

function getString(n)
  local dat = f:read(n)
  return dat:gsub("\x00", "")
end

function getLong()
  local long = { string.unpack("I8", f:read(8), 1) }
  return long[1]
end

function extract(name, offset, length)
  of = io.open(name, "wb")
  f:seek("set", offset)
  of:write(f:read(length))
  of:close()
end

if #arg < 1 then
  abort("Usage: unpack.lua radio.img")
end

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

magic = getString(256)
if magic ~= "SINGLE_N_LONELY" then
  abort("Unsupported")
end

fsize = f:seek("end")
f:seek("set", 256)

for i = 1,64 do
  name = getString(248)
  size = getLong()
  if name == "LONELY_N_SINGLE" then
    break -- no more files
  end
  io.write(string.format("Name: %s, Offset: %d, Size: %d", name, f:seek(), size))
  extract(name, f:seek(), size)
  pad = 0
  if size % 4096 ~= 0 then
    pad = 4096 - (size % 4096)
    f:read(pad)
  end
  print(", Padding: " .. pad)
end

f:close()