From 0f1b324cc44ed84f0cf0d8a970367bbb747d7f3e Mon Sep 17 00:00:00 2001
From: XeonSquared <redtailedairways@gmail.com>
Date: Fri, 5 Jun 2020 12:10:48 +1000
Subject: [PATCH] initial pkgfs work, seems functional

---
 lib/libmtar.lua | 112 ++++++++++++++++++++++++++++++++++++++++++++++++
 lib/pkgfs.lua   | 109 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 221 insertions(+)
 create mode 100644 lib/libmtar.lua
 create mode 100644 lib/pkgfs.lua

diff --git a/lib/libmtar.lua b/lib/libmtar.lua
new file mode 100644
index 0000000..0da8f7d
--- /dev/null
+++ b/lib/libmtar.lua
@@ -0,0 +1,112 @@
+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)
+ local n = 0
+ local i = 1
+ for p in s:gmatch(".") do
+  n = n << 8
+  n = n | string.byte(p)
+  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.iter(stream) -- table -- function -- Given buffer *stream*, returns an iterator suitable for use with *for* that returns, for each iteration, the file name, a function to read from the file, and the length of the file.
+ local remain = 0
+ local function read(n)
+  local rb = stream:read(math.min(n,remain))
+  remain = remain - rb:len()
+  return rb
+ end
+ return function()
+  stream:read(remain)
+  local nlen = toint(stream:read(2) or "\0\0")
+  if nlen == 0 then
+   return
+  end
+  local name = cleanPath(stream:read(nlen))
+  local fsize = toint(stream:read(2))
+  remain = fsize
+  return name, read, fsize
+ end
+end
+
+function mtar.unarchive(stream,dest,verbose) -- Extract mtar archive read from *stream* to *dest*. If *verbose*, print status.
+ dest = dest or "."
+ while true do
+  local nlen = toint(stream:read(2) or "\0\0")
+  if nlen == 0 then
+   break
+  end
+  local name = cleanPath(stream:read(nlen))
+  local fsize = toint(stream:read(2))
+  if verbose then
+   io.write(name.." "..tostring(fsize).."... ")
+  end
+  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,2048))
+    f:write(buf)
+    rsize = rsize - buf:len()
+    if verbose then
+     io.write(tostring(rsize).." ")
+    end
+   until rsize <= 1
+   f:close()
+  end
+  if verbose then
+   print("done.")
+  end
+ end
+end
+
+return mtar
diff --git a/lib/pkgfs.lua b/lib/pkgfs.lua
new file mode 100644
index 0000000..81332b5
--- /dev/null
+++ b/lib/pkgfs.lua
@@ -0,0 +1,109 @@
+local mtar = require "libmtar"
+local w, lz16 = pcall(require, "liblz16")
+if not w then lz16 = nil end
+
+pkgfs = {}
+local findex = {}
+local handles = {}
+local hc = 0
+
+local function rfalse()
+ return false
+end
+local function rzero()
+ return 0
+end
+
+pkgfs.component = {seek = rfalse, makeDirectory = rfalse, write = rfalse, rename = rfalse, setlabel = rfalse, spaceUsed = rzero, spaceTotal = rzero, lastModified = rzero}
+
+local function fopen(path,comp)
+ local f
+ if comp and lz16 then
+  f = lz16.open(path,"rb")
+ else
+  f = io.open(path,"rb")
+ end
+ return f
+end
+
+local function fnormalize(s)
+ return table.concat(fs.segments(s),"/")
+end
+
+function pkgfs.component.list(path)
+ path = fnormalize(path).."/"
+ local ft,rt = {},{}
+ for k,v in pairs(findex) do
+  k="/"..k
+  if k:match(path.."([^/]+)/.+") then
+   ft[k:match(path.."([^/]+)/.+").."/"] = true
+  elseif k:match(path.."([^/]+)") then
+   ft[k:match(path.."([^/]+)")] = true
+  end
+ end
+ for k,v in pairs(ft) do
+  rt[#rt+1] = k
+ end
+ return rt
+end
+function pkgfs.component.isDirectory(path)
+ path = fnormalize(path).."/"
+ for k,v in pairs(findex) do
+  k="/"..k
+  if k:match(path.."([^/]+)/.+") then
+   return true
+  end
+ end
+ return false
+end
+function pkgfs.component.size(path)
+ path=fnormalize(path)
+ if not findex[path] then return false end
+ local f = fopen(findex[path][1], findex[path][2])
+ for fname, read, fsize in mtar.iter(f) do
+  if fname == path then
+   return fsize
+  end
+ end
+ return false
+end
+
+function pkgfs.component.open(path,mode)
+ path=fnormalize(path)
+ if mode:find("w") or mode:find("a") or not findex[path] then
+  return false
+ end
+ local f = fopen(findex[path][1],findex[path][2])
+ for fname,read,fsize in mtar.iter(f) do
+  if fname == path then
+   hc = hc + 1
+   handles[hc] = {read, f}
+   return hc
+  end
+ end
+end
+
+function pkgfs.component.read(handle, n)
+ if not handles[handle] then return false end
+ local rv = handles[handle][1](n)
+ if not rv then return nil end
+ if rv:len() < 1 then return nil end
+ return rv
+end
+
+function pkgfs.component.close(handle)
+ if not handles[handle] then return false end
+ handles[handle][2]:close()
+ handles[handle] = nil
+ return true
+end
+
+function pkgfs.add(fname,comp)
+ local f = fopen(fname,comp)
+ for name, read, fsize in mtar.iter(f) do
+  findex[fnormalize(name)] = {fname,comp}
+ end
+ f:close()
+end
+
+return pkgfs