89 lines
2.5 KiB
Lua
89 lines
2.5 KiB
Lua
---
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-- Strict declared global library. Checks for undeclared global variables
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-- during runtime execution.
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--
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-- This module places the <code>strict</code> function in the global
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-- environment. The strict function allows a script to add runtime checking so
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-- that undeclared globals cause an error to be raised. This is useful for
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-- finding accidental use of globals when local was intended.
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--
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-- A global variable is considered "declared" if the script makes an assignment
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-- to the global name (even <code>nil</code>) in the file scope.
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--
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-- @class module
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-- @name strict
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-- @copyright Same as Nmap--See https://nmap.org/book/man-legal.html
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local debug = require "debug"
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local error = error;
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local getmetatable = getmetatable;
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local rawset = rawset;
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local rawget = rawget;
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local setmetatable = setmetatable;
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local type = type;
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local getinfo = debug.getinfo;
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_ENV = {};
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local function what ()
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local d = getinfo(3, "S");
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return d and d.what or "C";
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end
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--- The strict function.
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--
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-- This function adds runtime checking to the global environment for use of
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-- undeclared globals. A global is 'undeclared' if not assigned in the file
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-- (script) scope previously. An error will be raised on use of an undeclared
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-- global.
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--
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-- This function should be passed last to stdnse.module in order to allow
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-- other environment option functions (e.g. stdnse.seeall) to change the
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-- environment first. This is important for allowing globals outside the
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-- library (in _G) to be indexed.
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--
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-- @see stdnse.module
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-- @usage
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-- _ENV = stdnse.module(name, require "strict");
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-- @param env The environment to modify.
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local function strict (env)
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local mt = getmetatable(env) or setmetatable(env, {}) and getmetatable(env);
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local _newindex, _index = mt.__newindex, mt.__index;
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mt.__declared = {};
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function mt.__newindex (t, n, v)
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if type(_newindex) == "function" then
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_newindex(t, n, v); -- hook it
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end
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if not mt.__declared[n] then
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local w = what();
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if w ~= "main" and w ~= "C" then
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error("assign to undeclared variable '"..n.."'", 2);
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end
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mt.__declared[n] = true;
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end
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rawset(t, n, v);
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end
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function mt.__index (t, n)
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if type(_index) == "function" then
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local v = _index(t, n); -- hook it
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if v ~= nil then return v end
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elseif _index ~= nil then
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local v = _index[n];
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if v ~= nil then return v end
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end
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if not mt.__declared[n] and what() ~= "C" then
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error("variable '"..n.."' is not declared", 2);
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end
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return rawget(t, n);
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end
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return env;
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end
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return strict;
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