debug.getupvalue

Returns the upvalue at a given index in a closure or a running stack frame.

debug.getupvalue(func: function | number, index: number): any

New to upvalues? Learn more here.

Give it a number instead of a function and the number is treated as a stack level - 0 is the call running right now, 1 its caller, and so on - and the upvalue comes from whatever closure is running there.

Most commonly used while reversing a game script: grab a closure with getgc and read its upvalues to see the state it holds before deciding whether to read, change, or hook it.

Parameters

Parameter	Type	Description
func	function or number	The closure to read from.
index	number	Which upvalue to read, counting from 1.

Returns

any - whatever the closure stored at that slot. The type is not fixed: a table, an Instance, a function, and so on.

Aliases

• getupvalue

Example

A closure that captures a table, read straight back out by index:

Example 1

local getupvalue = debug.getupvalue(function(...) end, 1)

Give it a number instead of a function and the number is treated as a stack level - 0 is the call running right now, 1 its caller, and so on - and the upvalue comes from whatever closure is running there.