tape = {}
tape.types = {}
tape.types["!"] = "executable"
tape.types["t"] = "tar"
tape.types["d"] = "data"
tape.types["D"] = "directory"
tape.types["f"] = "file"
function tape.records(addr) -- { { type, start, end, length } }
 local tp,ct = {},0
 addr = addr or component.list("tape_drive")()
 local t = component.proxy(addr)
 local function read(n)
  n=n or 1
  ct=ct+n
  return t.read(n)
 end
 local function seek(n)
  n=n or 1
  ct=ct+n
  return t.seek(n)
 end
 while true do
  local ty = read()
  if not tape.types[ty] then break end
  tp[#tp+1] = {ty,ct+8} -- type, start,
  local ln = tonumber(read(8)) or 0
  tp[#tp][#tp[#tp]+1] = ct+ln -- end
  tp[#tp][#tp[#tp]+1] = ln -- length
  seek(ln)
 end
 return tp
end
function tape.precords(addr)
 tape.rewind(addr)
 local pt = tape.records(addr)
 for k,v in ipairs(pt) do
  print(k.."\t"..v[1].."\t"..v[2].."\t"..v[3].."\t"..v[4])
 end
end
function tape.drecord(n,addr)
 addr = addr or component.list("tape_drive")()
 tape.rewind(addr)
 local pt = tape.records(addr)
 tape.rewind(addr)
 local t = component.proxy(addr)
 print(pt[n][2]-9)
 t.seek(pt[n][2]-9)
 t.write("\0")
 tape.rewind()
end
function tape.wrecord(c,ty,s,addr)
 ty = ty or "!"
 addr = addr or component.list("tape_drive")()
 local t = component.proxy(addr)
 if s then
  t.seek(-math.huge)
  t.seek(s)
 end
 local fh=ty:sub(1,1)..string.format("%8d",c:len())
 print("Header: "..fh)
 t.write(fh)
 t.write(c)
end
function tape.rrecord(pn,addr)
 addr = addr or component.list("tape_drive")()
 pn = pn or 1
 local t = component.proxy(addr)
 local pP = t.seek(-math.huge)
 local pt = tape.records(addr)
 t.seek(-math.huge)
 local pstart,plen = pt[pn][2],pt[pn][4]
 t.seek(pstart)
 C=t.read(plen)
 t.seek(-math.huge)
 t.seek(pP)
 return C
end
function tape.nrecord(addr)
 addr = addr or component.list("tape_drive")()
 local t = component.proxy(addr)
 local pP = t.seek(-math.huge)
 local pt = tape.records(addr)
 t.seek(-math.huge)
 t.seek(pP)
 return pt[#pt][3]
end
function tape.rewind(addr)
 addr = addr or component.list("tape_drive")()
 local t = component.proxy(addr)
 t.seek(-math.huge)
end
function tape.parsefile(str)
 return str:sub(1,64):gsub("\0",""), str:sub(65)
end
function tape.unparsefile(fname,str)
 local nul = "\0"
 nul=nul:rep(64-#fname)
 fname=nul..fname
 return fname..str
end
function tape.mkdir(str,addr)
 tape.wrecord(str,"D",tape.nrecord(),addr)
end
function tape.wfile(fname,fcont,addr)
 tape.wrecord(str,"f",tape.nrecord(),addr)
end
function tape.wtree(addr)
 local ft = {""}
 local rft = {}
 addr = addr or component.list("tape_drive")()
 local t = component.proxy(addr)
 for _,d in ipairs(ft) do
  local ls = fs.list(d)
  for k,v in ipairs(ls) do
   v=d..v
   if fs.isdir(v) then
    ft[#ft+1] = v
   else
    rft[#rft+1] = v
   end
  end
 end
 tape.rewind(addr)
 t.seek(tape.nrecord(addr))
 for k,v in ipairs(ft) do
  if v ~= "" then
  print(v)
  local fh="D"..string.format("%8d",v:len())
  t.write(fh)
  t.write(v)
  end
 end
 for k,v in ipairs(rft) do
  print(v)
  local f=io.open(v,"rb")
  local fc = f:read("*a")
  local fc = tape.unparsefile(v,fc)
  f:close()
  local fh="f"..string.format("%8d",fc:len())
  t.write(fh)
  t.write(fc)
 end
end
function tape.rtree(pref,addr)
 tape.rewind()
 local pt = tape.records()
 for k,v in ipairs(pt) do
  if v[1] == "D" then
   print(tostring(k).."\t"..v[1].."\t"..pref..tape.rrecord(k))
   fs.mkdir(pref..tape.rrecord(k))
  elseif v[1] == "f" then
   local fn,fc = tape.parsefile(tape.rrecord(k))
   print(tostring(k).."\t"..v[1].."\t"..pref..fn)
   local f=io.open(pref..fn,"wb")
   f:write(fc)
   f:close()
  end
  computer.beep()
  coroutine.yield()
 end
end