globalsplus.lua for DetectingUndefinedVariables

globalsplus.lua

-- globalsplus.lua
-- Like globals.lua in Lua 5.1.4 but records fields in global tables too.
-- Probably works but not well tested.  Could be extended even further.
--
-- usage: luac -p -l example.lua  | lua globalsplus.lua
--
-- D.Manura, 2010-07, public domain

local function parse(line)
  local idx,linenum,opname,arga,argb,extra =
    line:match('^%s+(%d+)%s+%[(%d+)%]%s+(%w+)%s+([-%d]+)%s+([-%d]+)%s*(.*)')
  if idx then
    idx = tonumber(idx)
    linenum = tonumber(linenum)
    arga = tonumber(arga)
    argb = tonumber(argb)
  end
  local argc, const
  if extra then
    local extra2
    argc, extra2 = extra:match('^([-%d]+)%s*(.*)')
    if argc then argc = tonumber(argc); extra = extra2 end
  end
  if extra then
    const = extra:match('^; (.+)')
  end
  return {idx=idx,linenum=linenum,opname=opname,arga=arga,argb=argb,argc=argc,const=const}
end

local function getglobals(fh)
  local globals = {}
  local last
  for line in fh:lines() do
    local data = parse(line)
    if data.opname == 'GETGLOBAL' then
      data.gname = data.const
      last = data
      table.insert(globals, {linenum=last.linenum, name=data.const, isset=false})
    elseif data.opname == 'SETGLOBAL' then
      last = data
      table.insert(globals, {linenum=last.linenum, name=data.const, isset=true})
    elseif (data.opname == 'GETTABLE' or data.opname == 'SETTABLE') and last and
           last.gname and last.idx == data.idx-1 and last.arga == data.arga and data.const
    then
      local const = data.const:match('^"(.*)"')
      if const then
        data.gname = last.gname .. '.' .. const
        last = data
        table.insert(globals, {linenum=last.linenum, name=data.gname, isset=data.opname=='SETTABLE'})
      end
    else
      last = nil
    end
  end
  return globals
end

local function rindex(t, name)
  for part in name:gmatch('%w+') do
    t = t[part]
    if t == nil then return nil end
  end
  return t
end

local whitelist = _G

local globals = getglobals(io.stdin)
table.sort(globals, function(a,b) return a.linenum < b.linenum end)
for i,v in ipairs(globals) do
   local found = rindex(whitelist, v.name)
   print(v.linenum, v.name, v.isset and 'set' or 'get', found and 'defined' or 'undefined')
end

output.txt

luac -p -l test/sieve.lua | lua globalsplus.lua
5       gen     set     undefined
6       coroutine.wrap  get     defined
6       coroutine       get     defined
7       coroutine       get     defined
7       coroutine.yield get     defined
12      filter  set     undefined
13      coroutine       get     defined
13      coroutine.wrap  get     defined
17      math    get     defined
17      math.mod        get     defined
17      coroutine       get     defined
17      coroutine.yield get     defined
22      N       set     undefined
22      N       get     undefined
23      gen     get     undefined
23      x       set     undefined
23      N       get     undefined
25      x       get     undefined
27      print   get     defined
28      filter  get     undefined
28      x       set     undefined
28      x       get     undefined