Almost done cext implementation

cext.lua

--[[
  A lightweight ext-like FS implemented in pure lua.

  Specs: <insert link here>

  @author Jared Allard <[email protected]>
  @license MIT
  @notice uses JSDoc like insource documention.
]]

-- intial declearation of the FS table.
local cext = {
  ["version"] = 001,
  ["date"]    = 20150530,
  ["inodeAllocations"] = 500, -- amount of lines to save for inodes untill dynamic.
  ["print"] = function(msg)
    return nil -- no output
  end,
  ["fs"] = nil, -- assurance.
}

-- temporary.

-- split a string
function string.split(s, delimiter)
    result = {};
    for match in (s..delimiter):gmatch("(.-)"..delimiter) do
        table.insert(result, match);
    end
    return result;
end


--[[
  Create a filesystem.

  @return {boolean} - success or failure
]]
cext.createFS = function(this, location, size)
  -- this.checkArgs(this, size)

  -- superblockHeader.
  local superblockHeader = this.version..",0,"..size..",1"
  local inodeAllocation = ""

  -- generate whitespace.
  this.print("generating lines of whitespace.")
  for i = 1,this.inodeAllocations do
   inodeAllocation = inodeAllocation.."\n"
  end

  local contents = this.inodeAllocations+1

  -- remove a stale filesystem.
  if fs.exists(location) then
    this.print("removing stale fs")
    fs.delete(location)
  end

  -- open a io file handle and inject the superblockHeader & inodeAllocation ws.
  this.print("writing fs")
  local iohandle = io.open(location, "w")
  iohandle:write(superblockHeader..","..tostring(contents)..inodeAllocation)
  iohandle:close()
  this.print("done")

  -- return true since we probably had no issues.
  return true
end

--[[
  Open the file system (essentially load it into memory)

  @return {boolean} - success or fail.
]]
cext.open = function(this, filesystem)
  -- give the fs object an initial start.
  this.fs = {
    ["superblock"] = nil,
    ["data"]       = nil,
    ["path"]       = nil,
  }

  -- load the raw filesystem.
  local iohandle = fs.open(filesystem, "r")
  this.fs.superblock = iohandle.readLine()
  this.fs.data = iohandle.readAll() -- read the data raw. This includes inodes.
  iohandle.close()

  -- look at the superblock for the next available inode line.
  local superblockSplit = string.split(this.fs.superblock, ",")

  -- assign it to the table.
  this.fs.superblock = {}
  this.fs.superblock.version = superblockSplit[1]
  this.fs.superblock.inodes = superblockSplit[2]
  this.fs.superblock.size = superblockSplit[3]
  this.fs.superblock.nextInode = superblockSplit[4]
  this.fs.superblock.nextContents = superblockSplit[5]

  -- probably no errors, so set the path.
  this.fs.path = filesystem

  this.print('opened cext filesystem version: '..this.fs.superblock.version)

  -- return true as we probably had no issues.
  return true
end

--[[
  Close the filesystem. (write to disk)

  @return {boolean} - success or fail
]]
cext.close = function(this)
  local superblock = this.fs.superblock.version..","..this.fs.superblock.inodes..
    ","..this.fs.superblock.size..","..this.fs.superblock.nextInode..","..
    this.fs.superblock.nextContents

  local data = this.fs.data

  -- create the final object of the fs.
  local filesystem = superblock..data

  local fshandle = fs.open(this.fs.path, "w")
  fshandle.write(filesystem)
  fshandle.close()

  this.print("cext: this.fs.data_table = "..tostring(this.fs.data_table))

  return true
end

--[[
  Write to the filesystem

  @return {boolean} - success or fail, if fail then error message
    on second param return.
]]
cext.write = function(this, filename, data)
  if this.fs == nil then
    error("fs isn't loaded. load with this:open(fs)")
  end

  local fileLocation = fs.getDir(filename)
  local fileName     = fs.getName(filename)

  -- generate the object.
  this.print("generating inode for '"..tostring(filename).."'")
  local inodeObject = fileLocation..","..fileName

  -- write the filecontents.
  local nl = string.split(data, "\n")
  local min = this.fs.superblock.nextContents
  local max = min

  for i, v in pairs(nl) do
    max = max+1
    local n = this.fs.superblock.nextContents+(i-1)

    if i == #nl then
      this.print("cext: write: i is nl len. call asm.")
      this:writeToLine(n, v, true)
    else
      this:writeToLine(n, v)
    end
  end

  inodeObject = inodeObject..","..min.."-"..max

  -- print it out for now.
  this.print(inodeObject)

  this.print("fs.superblock.nextInode = "..tostring(this.fs.superblock.nextInode))

  -- write the new inode to the actual line.
  this:writeToLine(this.fs.superblock.nextInode, inodeObject, true)

  -- incrememnt the amount of inodes by 1.
  this.fs.superblock.nextInode = math.floor(this.fs.superblock.nextInode+1)

  -- increment the amount of content lines
  this.fs.superblock.nextContents = max

  return true
end

--[[
  Write to a line in the filesystem cache.

  @return {boolean} - success or fail.
]]
cext.writeToLine = function(this, line, data, asm)
  -- check if we've already been called. We should sync on asm = true
  if this.fs.data_table == nil then
    this.fs.data_table = string.split(this.fs.data, "\n")
  end

  -- write to the line, this is a very fragile operation.
  this.fs.data_table[line] = data

  if asm == true then
    this.print("cext: told to assemble the table into a string")
    -- convert the table into a string.
    local d = ""
    for i,v in pairs(this.fs.data_table) do
      d = d..v.."\n"
    end

    -- set the string as the new data object.
    this.fs.data = tostring(d)

    -- invalidate the table.
    this.fs.data_table = nil
  end

  -- since we are stil here, we had a successful write.
  return true
end

--[[
  Read the contents of a file.

  @return {string} - file contents, or nil on failure.
]]
cext.read = function(this, file)
  local inode = this.fs.data:match(file..",[a-z,0-9-]+")

  if inode == nil then
    -- doesn't exist.
    return nil
  end

  this.print("got: "..inode)

  local m = string.split(inode, ",")
  this.print("contents are on: "..m[2])

  return this:readLines(m[2])
end

cext.readLines = function(this, linesep)
  local nl = string.split(this.fs.data, "\n")
  local m = string.split(linesep, '-')
  local min = tonumber(m[1])
  local max = tonumber(m[2])

  local d = ""
  for i,v in pairs(nl) do
    if i > min and i < max then
      d = d..v.."\n"
    end
  end

  if d == "" then
    return false
  end

  return d
end


-- TESTING
fs.delete("test.fs")
cext:createFS("test.fs", 1000)
cext:open("test.fs")
cext:write("nothing", "hacky fix")
cext:close()
cext:write("ccdocker", fs.open("ccdocker", "r").readAll())
cext:close()

-- test file read.
cext:read("ccdocker")