From 5c9498493563c32c42a055cbbf9630818757ad27 Mon Sep 17 00:00:00 2001
From: Alex Orlenko <zxteam@protonmail.com>
Date: Fri, 13 Oct 2023 16:47:33 +0100
Subject: [PATCH] Add `lua_getallocf` API function (#1068)

This function matches the corresponding Lua 5.1-5.4 function:

[`lua_getallocf`](https://www.lua.org/manual/5.4/manual.html#lua_getallocf)
and [source](https://www.lua.org/source/5.4/lapi.c.html#lua_getallocf)

It would be useful to get/manipulate auxiliary "userdata" pointer that was originally passed to `lua_newstate`.
---
 VM/include/lua.h           |  2 ++
 VM/src/lapi.cpp            |  8 ++++++++
 tests/Conformance.test.cpp | 12 ++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/VM/include/lua.h b/VM/include/lua.h
index 43c60d77..1e8c30ba 100644
--- a/VM/include/lua.h
+++ b/VM/include/lua.h
@@ -323,6 +323,8 @@ LUA_API void lua_clonefunction(lua_State* L, int idx);
 
 LUA_API void lua_cleartable(lua_State* L, int idx);
 
+LUA_API lua_Alloc lua_getallocf(lua_State* L, void** ud);
+
 /*
 ** reference system, can be used to pin objects
 */
diff --git a/VM/src/lapi.cpp b/VM/src/lapi.cpp
index 2b98e47d..2d714566 100644
--- a/VM/src/lapi.cpp
+++ b/VM/src/lapi.cpp
@@ -1432,3 +1432,11 @@ size_t lua_totalbytes(lua_State* L, int category)
     api_check(L, category < LUA_MEMORY_CATEGORIES);
     return category < 0 ? L->global->totalbytes : L->global->memcatbytes[category];
 }
+
+lua_Alloc lua_getallocf(lua_State* L, void** ud)
+{
+    lua_Alloc f = L->global->frealloc;
+    if (ud)
+        *ud = L->global->ud;
+    return f;
+}
diff --git a/tests/Conformance.test.cpp b/tests/Conformance.test.cpp
index 1e520100..a023840b 100644
--- a/tests/Conformance.test.cpp
+++ b/tests/Conformance.test.cpp
@@ -1163,6 +1163,18 @@ TEST_CASE("ApiType")
     CHECK(lua_type(L, -1) == LUA_TUSERDATA);
 }
 
+TEST_CASE("AllocApi")
+{
+    int ud = 0;
+    StateRef globalState(lua_newstate(limitedRealloc, &ud), lua_close);
+    lua_State* L = globalState.get();
+
+    void* udCheck = nullptr;
+    bool allocfIsSet = lua_getallocf(L, &udCheck) == limitedRealloc;
+    CHECK(allocfIsSet);
+    CHECK(udCheck == &ud);
+}
+
 #if !LUA_USE_LONGJMP
 TEST_CASE("ExceptionObject")
 {