bootstrap.lua

local url = "https://gist.github.com/duff/4741476/raw/gfs.lua"
local body = http.get(url).readAll()

local handle = fs.open("/gfs", "w")
handle.write(body)
handle.close()

bootstrap_test.lua

require "mockcc"

http._register("https://gist.github.com/duff/4741476/raw/gfs.lua", "gfs body")

require "bootstrap"

assert(fs._at("/gfs"), "gfs program does not exist")
assert(fs._at("/gfs") == "gfs body", "gfs program has the wrong contents")

print "Passed"

gfs.lua

--[[
Gist File System

Takes a Gist ID and loads all Lua files into a named directory.

Usage: gfs install <gist id> <name>
       gfs refresh <name>
--]]

gfs = {}

local path = "/gists"

function gfs.setup()
  if not fs.exists(path) then
    fs.makeDir(path)
  end
end

function gfs.install(id, name, installTo)
  if not id or not name then
    gfs.usage()
  end

  gfs.setup()

  local installPath = installTo or fs.combine(path, name)

  assert(not fs.exists(installPath), "A gist with that name is already installed")

  local body = http.get("https://api.github.com/gists/" .. id).readAll()
  local gist = json.decode(body)

  assert(gist.files, "File info not found")

  fs.makeDir(installPath)

  local handle = fs.open(fs.combine(installPath, "id.txt"), "w")
  handle.write(id)
  handle.close()

  for name, details in pairs(gist.files) do
    if string.find(name, "%.lua$") then
      local newName = string.gsub(name, "%.lua$", "")
      handle = fs.open(fs.combine(installPath, newName), "w")
      handle.write(details.content)
      handle.close()
    end
  end
end

function gfs.refresh(name)
  if not name then
    gfs.usage()
  end

  local installPath = fs.combine(path, name)
  local handle = fs.open(fs.combine(installPath, "id.txt"), "r")
  assert(handle, "Cannot open file " .. fs.combine(installPath, "id.txt"))
  local id = handle.readAll()
  assert(id, "Cannot read id.txt")

  local tmpPath = fs.combine(path, "_tmp")
  gfs.install(id, name, tmpPath)
  fs.delete(installPath)
  fs.move(tmpPath, installPath)
end

function gfs.go(name)
  if not name then
    gfs.usage()
  end

  shell.setDir(fs.combine(path, name))
end

local function build_json()
  -- Source: http://hg.prosody.im/trunk/file/tip/util/json.lua
  -- License: http://hg.prosody.im/trunk/file/tip/COPYING

  local t_insert = table.insert;
  local s_char = string.char;
  local tonumber = tonumber;
  local ipairs = ipairs;
  local error = error;
  local newproxy = newproxy;
  local print = print;

  local json = {};

  local null = newproxy and newproxy(true) or {};
  json.null = null;

  local escapes = {
    ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b",
    ["\f"] = "\\f", ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};
  local unescapes = {
    ["\""] = "\"", ["\\"] = "\\", ["/"] = "/",
    b = "\b", f = "\f", n = "\n", r = "\r", t = "\t"};
  for i=0,31 do
    local ch = s_char(i);
    if not escapes[ch] then escapes[ch] = ("\\u%.4X"):format(i); end
  end

  function json.decode(json)
    json = json.." "; -- appending a space ensures valid json wouldn't touch EOF
    local pos = 1;
    local current = {};
    local stack = {};
    local ch, peek;
    local function next()
      ch = json:sub(pos, pos);
      if ch == "" then error("Unexpected EOF"); end
      pos = pos+1;
      peek = json:sub(pos, pos);
      return ch;
    end

    local function skipwhitespace()
      while ch and (ch == "\r" or ch == "\n" or ch == "\t" or ch == " ") do
        next();
      end
    end
    local function skiplinecomment()
      repeat next(); until not(ch) or ch == "\r" or ch == "\n";
      skipwhitespace();
    end
    local function skipstarcomment()
      next(); next(); -- skip '/', '*'
      while peek and ch ~= "*" and peek ~= "/" do next(); end
      if not peek then error("eof in star comment") end
      next(); next(); -- skip '*', '/'
      skipwhitespace();
    end
    local function skipstuff()
      while true do
        skipwhitespace();
        if ch == "/" and peek == "*" then
          skipstarcomment();
        elseif ch == "/" and peek == "/" then
          skiplinecomment();
        else
          return;
        end
      end
    end

    local readvalue;
    local function readarray()
      local t = {};
      next(); -- skip '['
      skipstuff();
      if ch == "]" then next(); return t; end
      t_insert(t, readvalue());
      while true do
        skipstuff();
        if ch == "]" then next(); return t; end
        if not ch then error("eof while reading array");
        elseif ch == "," then next();
        elseif ch then error("unexpected character in array, comma expected"); end
        if not ch then error("eof while reading array"); end
        t_insert(t, readvalue());
      end
    end

    local function checkandskip(c)
      local x = ch or "eof";
      if x ~= c then error("unexpected "..x..", '"..c.."' expected"); end
      next();
    end
    local function readliteral(lit, val)
      for c in lit:gmatch(".") do
        checkandskip(c);
      end
      return val;
    end
    local function readstring()
      local s = "";
      checkandskip("\"");
      while ch do
        while ch and ch ~= "\\" and ch ~= "\"" do
          s = s..ch; next();
        end
        if ch == "\\" then
          next();
          if unescapes[ch] then
            s = s..unescapes[ch];
            next();
          elseif ch == "u" then
            local seq = "";
            for i=1,4 do
              next();
              if not ch then error("unexpected eof in string"); end
              if not ch:match("[0-9a-fA-F]") then error("invalid unicode escape sequence in string"); end
              seq = seq..ch;
            end
            s = s..s.char(tonumber(seq, 16)); -- FIXME do proper utf-8
            next();
          else error("invalid escape sequence in string"); end
        end
        if ch == "\"" then
          next();
          return s;
        end
      end
      error("eof while reading string");
    end
    local function readnumber()
      local s = "";
      if ch == "-" then
        s = s..ch; next();
        if not ch:match("[0-9]") then error("number format error"); end
      end
      if ch == "0" then
        s = s..ch; next();
        if ch:match("[0-9]") then error("number format error"); end
      else
        while ch and ch:match("[0-9]") do
          s = s..ch; next();
        end
      end
      if ch == "." then
        s = s..ch; next();
        if not ch:match("[0-9]") then error("number format error"); end
        while ch and ch:match("[0-9]") do
          s = s..ch; next();
        end
        if ch == "e" or ch == "E" then
          s = s..ch; next();
          if ch == "+" or ch == "-" then
            s = s..ch; next();
            if not ch:match("[0-9]") then error("number format error"); end
            while ch and ch:match("[0-9]") do
              s = s..ch; next();
            end
          end
        end
      end
      return tonumber(s);
    end
    local function readmember(t)
      skipstuff();
      local k = readstring();
      skipstuff();
      checkandskip(":");
      t[k] = readvalue();
    end
    local function fixobject(obj)
      local __array = obj.__array;
      if __array then
        obj.__array = nil;
        for i,v in ipairs(__array) do
          t_insert(obj, v);
        end
      end
      local __hash = obj.__hash;
      if __hash then
        obj.__hash = nil;
        local k;
        for i,v in ipairs(__hash) do
          if k ~= nil then
            obj[k] = v; k = nil;
          else
            k = v;
          end
        end
      end
      return obj;
    end
    local function readobject()
      local t = {};
      next(); -- skip '{'
      skipstuff();
      if ch == "}" then next(); return t; end
      if not ch then error("eof while reading object"); end
      readmember(t);
      while true do
        skipstuff();
        if ch == "}" then next(); return fixobject(t); end
        if not ch then error("eof while reading object");
        elseif ch == "," then next();
        elseif ch then error("unexpected character in object, comma expected"); end
        if not ch then error("eof while reading object"); end
        readmember(t);
      end
    end

    function readvalue()
      skipstuff();
      while ch do
        if ch == "{" then
          return readobject();
        elseif ch == "[" then
          return readarray();
        elseif ch == "\"" then
          return readstring();
        elseif ch:match("[%-0-9%.]") then
          return readnumber();
        elseif ch == "n" then
          return readliteral("null", null);
        elseif ch == "t" then
          return readliteral("true", true);
        elseif ch == "f" then
          return readliteral("false", false);
        else
          error("invalid character at value start: "..ch);
        end
      end
      error("eof while reading value");
    end
    next();
    return readvalue();
  end

  return json;
end

json = build_json()

function gfs.usage()
  print([=[
Usage: gfs install <gist id> <name>
       gfs refresh <name>
       gfs go <name>
]=])
  error("Command not understood.")
end

if not debug or string.find(debug.getinfo(1).source, arg[0] .. "$") then
  local arg = {...}
  if gfs[arg[1]] then
    gfs[arg[1]](arg[2], arg[3])
  else
    gfs.usage()
  end
end

gfs_test.lua

require "mockcc"

require "gfs"

local function setup()
  fs._reset()
  http._reset()
end

local function testInstall()
  setup()
  http._register("https://api.github.com/gists/1", [=[
{
  "files": {
    "uno.lua": {
      "filename": "uno.lua",
      "content": "hi"
    },
    "dos.lua": {
      "filename": "dos.lua",
      "content": "bye"
    },
    "skip": {
      "filename": "skip",
      "content": "no"
    }
  }
}
]=])

  gfs.install("1", "one")

  assert(fs._at("/gists/one/id.txt"), "Missing the id file")
  assert(fs._read("/gists/one/id.txt") == "1", "The id file is incorrect: " .. fs._read("/gists/one/id.txt"))
  assert(fs._at("/gists/one/uno"), "Missing the first file")
  assert(fs._read("/gists/one/uno") == "hi", "The first file is incorrect: " .. fs._read("/gists/one/uno"))
  assert(fs._at("/gists/one/dos"), "Missing the second file")
  assert(fs._read("/gists/one/dos") == "bye", "The second file is incorrect: " .. fs._read("/gists/one/dos"))
  assert(not fs._at("/gists/one/skip"), "Did not skip non-Lua file")
end
testInstall()

local function testRefresh()
  setup()
  fs._write("/gists/two/id.txt", "2")
  fs._write("/gists/two/existing", "nice")
  fs._write("/gists/two/gone", "ouch")
  http._register("https://api.github.com/gists/2", [=[
{
  "files": {
    "new.lua": {
      "content": "sweet"
    },
    "existing.lua": {
      "content": "even better"
    }
  }
}
]=])

  gfs.refresh("two")

  assert(fs._at("/gists/two/id.txt"), "Missing the id file")
  assert(fs._read("/gists/two/id.txt") == "2", "The id file is incorrect: " .. fs._read("/gists/two/id.txt"))
  assert(fs._at("/gists/two/new"), "Missing the new file")
  assert(fs._read("/gists/two/new") == "sweet", "The new file is incorrect: " .. fs._read("/gists/two/new"))
  assert(fs._at("/gists/two/existing"), "Missing the existing file")
  assert(fs._read("/gists/two/existing") == "even better", "The existing file is incorrect: " .. fs._read("/gists/two/existing"))
  assert(not fs._at("/gists/two/gone"), "Did not remove the old file")
end
testRefresh()

local function testGo()
  setup()

  gfs.go("one")

  assert(shell._CURRENT == "/gists/one", "Incorrect current directory " .. shell._CURRENT)
end
testGo()

print("Passed")

mockcc.lua

fs = {
  _STORAGE = {},
  _reset = function() fs._STORAGE = {} end,
  _write = function(path, content) fs._STORAGE[path] = content end,
  open = function(path, mode)
    local contents = ""
    return {
      write = function(content)
        assert(mode == "w", "Attempting to write mode of " .. mode)
        contents = contents .. content
      end,
      readAll = function()
        assert(mode == "r", "Attempting to read mode of " .. mode)
        return fs._STORAGE[path]
      end,
      close = function() fs._STORAGE[path] = contents end
    }
  end,
  exists = function(path) return fs._STORAGE[path] end,
  makeDir = function(path) fs._STORAGE[path] = {} end,
  combine = function(first, last) return first .. "/" .. last end,
  delete = function(path)
    for fullpath, contents in pairs(fs._STORAGE) do
      if string.find(fullpath, "^" .. path) then
        fs._STORAGE[fullpath] = nil
      end
    end
  end,
  move = function(from, to)
    for fullpath, contents in pairs(fs._STORAGE) do
      if string.find(fullpath, "^" .. from) then
        local newpath = to .. string.gsub(fullpath, "^" .. from, "")
        assert(not fs._STORAGE[newpath], newpath .. " already exists")
        fs._STORAGE[newpath] = fs._STORAGE[fullpath]
        fs._STORAGE[fullpath] = nil
      end
    end
  end
}
fs._read = fs.exists
fs._at = fs.exists

http = {
  _STORAGE = {},
  _reset = function() fs._STORAGE = {} end,
  _register = function(url, contents)
    http._STORAGE[url] = contents
  end,
  get = function(url)
    if not http._STORAGE[url] then error("Unknown url " .. url) end
    return {
      readAll = function() return http._STORAGE[url] end
    }
  end
}

shell = {
  _CURRENT = "/",
  setDir = function(path) shell._CURRENT = path end
}