fix(env) luajit table overflow error when using ffi.cdef

[ms2008]

Summary

There is a potential risk that if init is invoked a lot, a table overflow error will occur. Can be verified very simply by:

$ resty -e 'local ffi = require "ffi" while true do ffi.cdef[[void exit(int status);]] end'
ERROR: table overflow
stack traceback:
        (command line -e):1: in function 'inline_gen'
        init_worker_by_lua:44: in function <init_worker_by_lua:43>
        [C]: in function 'xpcall'
        init_worker_by_lua:52: in function <init_worker_by_lua:50>

It's wrong to call ffi.cdef() repeatedly for the same things. Always call it on the top-level scope of module files.

Full changelog

• fix luajit table overflow error when using ffi.cdef

[bungle]

@ms2008, init is only ever executed once (in init phase of nginx).

[ms2008]

@bungle Sorry, I am not very familiar with the valut thing. I see it being called here:

kong/kong/pdk/vault.lua

Lines 163 to 165 in 802e1aa

	if strategy.init then
	strategy.init()
	end

will eventually be called by this method:

kong/kong/pdk/vault.lua

Line 388 in 802e1aa

function _VAULT.get(reference)

It looks like it might be called multiple times if I understand correctly:

kong/kong/db/schema/init.lua

Lines 1744 to 1760 in 802e1aa

	for i = 1, count do
	if is_reference(value[i]) then
	refs[key][i] = value[i]
	local deref, err = kong.vault.get(value[i])
	if deref then
	value[i] = deref
	else
	if err then
	kong.log.warn("unable to resolve reference ", value[i], " (", err, ")")
	else
	kong.log.warn("unable to resolve reference ", value[i])
	end
	value[i] = nil
	end
	end
	end

[bungle]

@bungle Sorry, I am not very familiar with the valut thing. I see it being called here:

kong/kong/pdk/vault.lua

Lines 163 to 165 in 802e1aa

	if strategy.init then
	strategy.init()
	end

will eventually be called by this method:

Good point. Let me check this too. The init might not be needed there, let me see. This is quite complicated as it has to work on CLI etc.