techpack/safer_lua/environ.lua

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--[[
SaferLua [safer_lua]
====================
Copyright (C) 2018 Joachim Stolberg
LGPLv2.1+
See LICENSE.txt for more information
environ.lua:
]]--
safer_lua.MaxCodeSize = 5000 -- size if source code in bytes
safer_lua.MaxTableSize = 1000 -- sum over all table sizes
safer_lua.MaxExeTime = 5000 -- max. execution time in us
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local function memsize()
return safer_lua.MaxTableSize
end
local function range(from, to)
return function(expired_at,last)
assert(expired_at > minetest.get_us_time(), "Runtime limit exceeded")
if last >= to then
return nil
else
return last+1
end
end, minetest.get_us_time() + safer_lua.MaxExeTime, from-1
end
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local BASE_ENV = {
Array = safer_lua.Array,
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Store = safer_lua.Store,
Set = safer_lua.Set,
memsize = memsize,
range = range,
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math = {
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floor = math.floor,
abs = math.abs,
max = math.max,
min = math.min,
random = math.random,
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},
string = {
byte = string.byte,
char = string.char,
find = string.find,
format = string.format,
gmatch = string.gmatch,
gsub = string.gsub,
len = string.len,
lower = string.lower,
match = string.match,
rep = string.rep,
sub = string.sub,
upper = string.upper,
},
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tonumber = tonumber,
tostring = tostring,
type = type,
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ticks = 0,
}
local function map(dest, source)
for k,v in pairs(source) do
dest[k] = v
end
return dest
end
local function calc_used_mem_size(env)
local size = 0
for key,val in pairs(env) do
if type(val) == "table" and val.size ~= nil then
size = size + val.size() or 0
end
end
return size
end
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function safer_lua.config(max_code_size, max_table_size)
safer_lua.MaxCodeSize = max_code_size
safer_lua.MaxTableSize = max_table_size
end
local function format_error_str(str, label)
local tbl = {}
for s in str:gmatch("[^\r\n]+") do
s = s:match("^%s*(.-)%s*$")
if s:find("function 'xpcall'") then
break
elseif s:find(".-%.lua:%d+:(.+)") then
local err = s:gsub(".-%.lua:%d+:%s*(.+)", "extern: %1")
table.insert(tbl, err)
elseif s:find('%[string ".-"%]') then
local line, err = s:match('^%[string ".-"%]:(%d+): (.+)$')
table.insert(tbl, label..":"..line..": "..err)
elseif s:find('%(load%):(%d+):') then
local line, err = s:match('%(load%):(%d+): (.+)$')
table.insert(tbl, label..":"..line..": "..err)
end
end
return "Error: "..table.concat(tbl, "\n >> ")
end
local function format_error(err, label)
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if err:find("stack overflow") then
return "Error: Stack overflow due to recursive function calls!"
end
return format_error_str(err, label)
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end
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local function compile(pos, text, label, err_clbk)
if safer_lua:check(pos, text, label, err_clbk) == 0 then
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text = text:gsub("%$", "S:")
local code, err = loadstring(text)
if not code then
err_clbk(pos, format_error(err, label))
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else
return code
end
end
end
-------------------------------------------------------------------------------
-- Standard init/loop controller
-------------------------------------------------------------------------------
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function safer_lua.init(pos, init, loop, environ, err_clbk)
if (#init + #loop) > safer_lua.MaxCodeSize then
err_clbk(pos, "Error: Code size limit exceeded")
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return
end
local code = compile(pos, init, "init", err_clbk, 0)
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if code then
local env = table.copy(BASE_ENV)
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env.S = {}
env.S = map(env.S, environ)
setfenv(code, env)
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local res, err = xpcall(code, debug.traceback)
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if not res then
err_clbk(pos, format_error(err, "init"))
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else
env = getfenv(code)
code = compile(pos, loop, "loop", err_clbk)
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if code then
setfenv(code, env)
return code
end
end
end
end
function safer_lua.run_loop(pos, elapsed, code, err_clbk)
local env = getfenv(code)
env.elapsed = elapsed
if elapsed < 0 then -- event?
env.event = true
else
env.event = false
env.ticks = env.ticks + 1
end
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local res, err = xpcall(code, debug.traceback)
if calc_used_mem_size(env) > safer_lua.MaxTableSize then
err_clbk(pos, "Error: Data memory limit exceeded")
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return false
end
if not res then
err_clbk(pos, format_error(err, "loop"))
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return false
end
return true
end
-------------------------------------------------------------------------------
-- Endless/Coroutine controller
-------------------------------------------------------------------------------
local function thread(pos, code, err_clbk)
while true do
local res, err = xpcall(code, debug.traceback)
if not res then
err_clbk(pos, format_error(err, "loop"))
return false
end
local env = getfenv(code)
if calc_used_mem_size(env) > safer_lua.MaxTableSize then
err_clbk(pos, "Error: Memory limit exceeded")
return false
end
coroutine.yield()
end
end
function safer_lua.co_create(pos, init, loop, environ, err_clbk)
local code = safer_lua.init(pos, init, loop, environ, err_clbk)
return coroutine.create(thread), code
end
function safer_lua.co_resume(pos, co, code, err_clbk)
local res, err = coroutine.resume(co, pos, code, err_clbk)
if not res then
err_clbk(pos, format_error(err, "loop"))
return false
end
return true
end