debug.getproto

C closures are not supported

This function will throw an error if called on a C closure, such as print, since C closures do not contain function prototypes.

Inactive protos

Protos retrieved without the activated should not be callable; this leads to vulnerabilities. The usage of inactive protos is to retrieve information off of them.

debug.getproto returns a specific function prototype from a Luau function by index. Optionally, it can search for active functions of the proto, if the activated parameter is set to true.

These are internal function definitions (e.g. nested functions) that exist as part of the compiled bytecode, even if they aren't assigned or called.

function debug.getproto(func: (...any) -> (...any) | number, index: number, activated: boolean?): (...any) -> (...any) | { (...any) -> (...any) }

Parameters

Parameter	Description
func	The Luau function (or stack level) to extract a proto from.
index	The index of the prototype to return.
activated?	If true, returns a table of currently active functions based on the proto.

---

Examples

Example 1

local function dummy_function()
    local function dummy_proto_1()
        print("Hello")
    end
    local function dummy_proto_2()
        print("Hello2")
    end
end

debug.getproto(dummy_function, 1)() -- Uncallable
debug.getproto(dummy_function, 2)() -- Uncallable

Example 2

local function dummy_function()
    local function dummy_proto()
        return "hi"
    end
    return dummy_proto
end

local real_proto = dummy_function()
local retrieved_proto = debug.getproto(dummy_function, 1, true)[1]

print(real_proto == retrieved_proto) -- Output: true
print(retrieved_proto()) -- Output: hi