编辑“模块:PreloadPoison”


local p = {}
function p.test(frame)
    local results = {}

    -- The key insight: if we modify package.preload["os"] and then os is re-required,
    -- the new os will be our custom version. But we're in the sandbox, so our custom
    -- version can't access blocked functions either.

    -- HOWEVER: what if we set package.preload to return the ORIGINAL os table
    -- by navigating through upvalues of existing functions?

    results[1] = "test_preload_poison"

    -- Try to find any reference to the original (unsandboxed) functions
    -- through the metatables of loaded C functions

    -- os.clock is a C function. C functions don't have upvalues, but...
    -- let's check if we can get its environment
    local os_tbl = require("os")
    local clock_fn = os_tbl.clock

    if type(clock_fn) == "function" then
        local info = pcall(debug.getinfo, clock_fn, "S")
        results[2] = "clock_info=" .. tostring(info)
    end

    -- Try calling debug.getinfo with specific args
    local si = pcall(debug.getinfo, clock_fn, "S")
    results[3] = "si=" .. tostring(si)

    return table.concat(results, " | ")
end
return p