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Главная → Статьи → Lua → lua eval
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Written by xternalx   
Sunday, 17 January 2010 02:41

Кто знает для чего нужен eval и когда он может пригодиться - тот знает. Кто не знает - тому оно не надо.

Для нуждающихся выкладываю копипаст откуда то:

 


sandbox = sandbox or { ai = { patterns = {} }};

function eval(e, ex)
if not e:match("^[%a%d%p%s]+$") then print(e.." does not match\n\n"); return false, "Send me some real Lua, eh?"; end
local chunk, errmsg = loadstring("return "..e);
array = table;
if not chunk then
chunk, errmsg = loadstring(e);
if chunk and ex and (not ex.allow_functions) then
return false, "That's something I could not allow to happen.";
end
if not chunk then return false, "Syntax error: "..errmsg; end
end

for k, v in pairs(math) do sandbox[k] = v end
for k, v in pairs(string) do sandbox[k] = v end
if ex and ex.data then
for k, v in pairs(ex.data) do sandbox[k] = v end
end
sandbox.dump = nil;
sandbox.array = array;
sandbox.table = table;
sandbox.time = os.time;
sandbox.difftime = os.difftime;
sandbox.clock = os.clock;
sandbox.date = os.date;
sandbox.RAM = MemUsage;
sandbox.tostring = tostring;
sandbox.tonumber = tonumber;
sandbox.select = select;
sandbox.type = type;
sandbox.unpack = unpack;
sandbox.print = function (a) return a; end
sandbox.pairs = pairs;
sandbox.ipairs = ipairs;
sandbox.assert = assert;
sandbox.count = table.fieldcount;

if ex and ex.allow_mtaccess then
sandbox.setmetatable = setmetatable;
sandbox.getmetatable = getmetatable;
end

setfenv(chunk, sandbox)
sandbox["sandbox"] = sandbox;

StartTime = os.time();
debug.sethook(NewWatchdog(),"", 10);

results = { pcall(chunk) };
debug.sethook(); -- Remove hook
StartTime = nil;
if not results[1] then
return false, "Error: "..results[2], "error";
end
table.remove(results, 1); -- Remove status code
if #results == 0 then return nil, ChooseResponse("{Done :)}{Done}{Ok}{That's done}{As you wish}"); end
for k, v in ipairs(results) do results[k] = tostring(v); end
return true, table.concat(results, ", ");
end

function NewWatchdog(tim)
local StartTime = os.time();
local MaxRunTime = 2;
return function ()
-- This is a debug hook, to ensure functions run in the sandbox end within n seconds
-- if StartTime == nil then print("StartTime is nil"); StartTime = os.time(); end
-- print("Hook time: "..os.difftime(StartTime, os.time()))
if os.difftime(os.time(),StartTime) > MaxRunTime then
debug.sethook();
error("Sorry, the function ran too long, unable to complete", 2); end
if MemUsage() > (1024 * 2) then -- 2MB
debug.sethook();
error("Sorry, I am not allowed to use that much memory. Please try more efficient code ;)", 2); end
end
end

sandbox = sandbox or { ai = { patterns = {} }};

function eval(e, ex)
if not e:match("^[%a%d%p%s]+$") then print(e.." does not match\n\n"); return false, "Send me some real Lua, eh?"; end
local chunk, errmsg = loadstring("return "..e);
array = table;
if not chunk then
chunk, errmsg = loadstring(e);
if chunk and ex and (not ex.allow_functions) then
return false, "That's something I could not allow to happen.";
end
if not chunk then return false, "Syntax error: "..errmsg; end
end

for k, v in pairs(math) do sandbox[k] = v end
for k, v in pairs(string) do sandbox[k] = v end
if ex and ex.data then
for k, v in pairs(ex.data) do sandbox[k] = v end
end
sandbox.dump = nil;
sandbox.array = array;
sandbox.table = table;
sandbox.time = os.time;
sandbox.difftime = os.difftime;
sandbox.clock = os.clock;
sandbox.date = os.date;
sandbox.RAM = MemUsage;
sandbox.tostring = tostring;
sandbox.tonumber = tonumber;
sandbox.select = select;
sandbox.type = type;
sandbox.unpack = unpack;
sandbox.print = function (a) return a; end
sandbox.pairs = pairs;
sandbox.ipairs = ipairs;
sandbox.assert = assert;
sandbox.count = table.fieldcount;

if ex and ex.allow_mtaccess then
sandbox.setmetatable = setmetatable;
sandbox.getmetatable = getmetatable;
end

setfenv(chunk, sandbox)
sandbox["sandbox"] = sandbox;

StartTime = os.time();
debug.sethook(NewWatchdog(),"", 10);

results = { pcall(chunk) };
debug.sethook(); -- Remove hook
StartTime = nil;
if not results[1] then
return false, "Error: "..results[2], "error";
end
table.remove(results, 1); -- Remove status code
if #results == 0 then return nil, ChooseResponse("{Done :)}{Done}{Ok}{That's done}{As you wish}"); end
for k, v in ipairs(results) do results[k] = tostring(v); end
return true, table.concat(results, ", ");
end

function NewWatchdog(tim)
local StartTime = os.time();
local MaxRunTime = 2;
return function ()
-- This is a debug hook, to ensure functions run in the sandbox end within n seconds
-- if StartTime == nil then print("StartTime is nil"); StartTime = os.time(); end
-- print("Hook time: "..os.difftime(StartTime, os.time()))
if os.difftime(os.time(),StartTime) > MaxRunTime then
debug.sethook();
error("Sorry, the function ran too long, unable to complete", 2); end
if MemUsage() > (1024 * 2) then -- 2MB
debug.sethook();
error("Sorry, I am not allowed to use that much memory. Please try more efficient code ;)", 2); end
end
end

 

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Last Updated on Wednesday, 03 February 2010 23:37
 

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