added a minitel archive library

mtar/libmtar.lua

@@ -0,0 +1,89 @@
+local mtar = {}
+
+-- detect OS hopefully
+if _OSVERSION then
+ if _OSVERSION:sub(1,8) == "OpenOS" then
+  OPENOS = true
+ elseif _OSVERSION:sub(1,9) == "PsychOS" then
+  PSYCHOS = true
+ end
+else
+ LINUX = true
+end
+
+local function mkdir(dir)
+ if OPENOS or LINUX then
+  os.execute("mkdir "..dest.."/"..dir.." &> /dev/null")
+ elseif PSYCHOS then
+  -- todo: write PsychOS support
+ end
+end
+
+local function toint(s)
+ s=s or ""
+ local n = 0
+ local i = 1
+ while true do
+  local p = s:sub(i,i)
+  if p == "" then break end
+  local b = string.byte(p)
+  n = n << 8
+  n = n | b
+  i=i+1
+ end
+ return n
+end
+
+local function cint(n,l)
+ local t={}
+ for i = 0, 7 do
+  t[i+1] = (n >> (i * 8)) & 0xFF
+ end
+ return string.reverse(string.char(table.unpack(t)):sub(1,l))
+end
+
+local function cleanPath(path)
+ local pt = {}
+ for segment in path:gmatch("[^/]+") do
+  if segment == ".." then
+   pt[#pt] = nil
+  elseif segment ~= "." then
+   pt[#pt+1] = segment
+  end
+ end
+ return table.concat(pt,"/")
+end
+
+function mtar.genHeader(fname,len) -- generate a header for file *fname* when provided with file length *len*
+ return string.format("%s%s%s",cint(fname:len(),2),fname,cint(len,2))
+end
+
+function mtar.unarchive(stream,dest)
+ dest = dest or "."
+ mkdir(dest)
+ while true do
+  local nlen = toint(stream:read(2))
+  if nlen == 0 then
+   break
+  end
+  local name = cleanPath(stream:read(nlen))
+  local fsize = toint(stream:read(2))
+  print(name,fsize)
+  local dir = name:match("(.+)/.*%.?.+")
+  if (dir) then
+   mkdir(dir)
+  end
+  local f = io.open(dest.."/"..name,"wb")
+  local rsize,buf = fsize, ""
+  if f then
+   repeat
+    buf = stream:read(math.min(rsize,1024))
+    f:write(buf)
+    rsize = rsize - buf:len()
+   until rsize <= 1
+   f:close()
+  end
+ end
+end
+
+return mtar