do
 _G.fs = {}
 local fT,hT = {},{["_c"]=0}
 function fs.mount(mp,pr)
  fT[mp] = pr
 end
 function fs.simplify(p)
  local pt,npt,rp = {},{},""
  for P in p:gmatch("[^/]+") do
   pt[#pt+1] = P
  end
  for k,v in pairs(pt) do
   if v == ".." then
    npt[#npt] = nil
   elseif v ~= "." then
    npt[#npt+1] = v
   end
  end
  for k,v in pairs(npt) do
   rp=rp.."/"..v
  end
  if p:sub(1,1) ~= "/" then rp = rp:sub(2) end
  return rp
 end
 function fs.resolve(p)
  if p:sub(1,1) ~= "/" then -- absolute/relative path
   p=(os.getenv("PWD") or "").."/"..p
  end
  p=fs.simplify(p)
  local pt = {}
  for P in p:gmatch("[^/]+") do
   pt[#pt+1] = P
  end
  return pt, p:match("/?(.-)/"), p:match("/?.-/(.+)")
 end
 function fs.open(p,m)
  local _,d,p = fs.resolve(p)
  local d = fT[d]
  local f,C=d.open(p,m),hT._c
  if f then
   hT._c = C + 1
   hT[C] = {d,f}
   return C
  end
  return false
 end
 function fs.close(h)
  if hT[h] then
   hT[h][1].close(hT[h][2])
  end
  return false
 end
 function fs.read(h,n)
  if hT[h] then
   return hT[h][1].read(hT[h][2],n)
  end
  return false
 end
 function fs.readall(f)
  local s=""
  repeat
   c=fs.read(f,2048)
   s=s..c
  until c==""
  return s
 end
 function fs.write(h,d)
  if hT[h] then
   return hT[h][1].write(hT[h][2],d)
  end
  return false
 end
end