LUA_REGISTRYINDEX

3 files changed, 28 insertions, 6 deletions

diff --git a/src/lapi.js b/src/lapi.js
index 41c0fbb..dd74552 100644
--- a/src/lapi.js
+++ b/src/lapi.js
@@ -35,12 +35,13 @@ const index2addr = function(L, idx) {
         assert(idx <= ci.top - (ci.funcOff + 1), "unacceptable index");
         if (o >= L.top) return ldo.nil;
         else return L.stack[o];
-    } else if (idx < 0) { // TODO: pseudo-indices relative to LUA_REGISTRYINDEX
+    } else if (idx > lua.LUA_REGISTRYINDEX) {
         assert(idx !== 0 && -idx <= L.top, "invalid index");
         return L.stack[L.top + idx];
-    // TODO: if (idx == LUA_REGISTRYINDEX) return &G(L)->l_registry;
+    } else if (idx === lua.LUA_REGISTRYINDEX) {
+        return L.l_G.l_registry;
     } else { /* upvalues */
-        idx = -idx;
+        idx = lua.LUA_REGISTRYINDEX - idx;
         assert(idx <= MAXUPVAL + 1, "upvalue index too large");
         if (ci.func.ttislcf()) /* light C function? */
             return ldo.nil; /* it has no upvalues */
diff --git a/src/lua.js b/src/lua.js
index 245c826..58cc0cd 100644
--- a/src/lua.js
+++ b/src/lua.js
@@ -1,8 +1,9 @@
 /*jshint esversion: 6 */
 "use strict";
 
-const assert = require('assert');
-const lualib = require('./lualib.js');
+const assert  = require('assert');
+const lualib  = require('./lualib.js');
+const luaconf = require('./luaconf.js');
 
 const LUA_VERSION_MAJOR       = "5";
 const LUA_VERSION_MINOR       = "3";
@@ -64,6 +65,12 @@ constant_types.LUA_TCCL = constant_types.LUA_TFUNCTION | (2 << 4);  /* C closure
 const LUA_NUMTAGS = 9;
 const LUA_MINSTACK = 20;
 
+const LUA_REGISTRYINDEX = -luaconf.LUAI_MAXSTACK - 1000;
+
+const lua_upvalueindex = function(i) {
+    LUA_REGISTRYINDEX - i;
+};
+
 /* predefined values in the registry */
 const LUA_RIDX_MAINTHREAD = 1;
 const LUA_RIDX_GLOBALS    = 2;
@@ -99,4 +106,6 @@ module.exports.LUA_NUMTAGS             = LUA_NUMTAGS;
 module.exports.LUA_MINSTACK            = LUA_MINSTACK;
 module.exports.LUA_RIDX_MAINTHREAD     = LUA_RIDX_MAINTHREAD;
 module.exports.LUA_RIDX_GLOBALS        = LUA_RIDX_GLOBALS;
-module.exports.LUA_RIDX_LAST           = LUA_RIDX_LAST;
\ No newline at end of file
+module.exports.LUA_RIDX_LAST           = LUA_RIDX_LAST;
+module.exports.LUA_REGISTRYINDEX       = LUA_REGISTRYINDEX;
+module.exports.lua_upvalueindex        = lua_upvalueindex;
\ No newline at end of file
diff --git a/src/luaconf.js b/src/luaconf.js
new file mode 100644
index 0000000..b0456e3
--- /dev/null
+++ b/src/luaconf.js
@@ -0,0 +1,12 @@
+/*jshint esversion: 6 */
+"use strict";
+
+/*
+@@ LUAI_MAXSTACK limits the size of the Lua stack.
+** CHANGE it if you need a different limit. This limit is arbitrary;
+** its only purpose is to stop Lua from consuming unlimited stack
+** space (and to reserve some numbers for pseudo-indices).
+*/
+const LUAI_MAXSTACK = 1000000;
+
+module.exports.LUAI_MAXSTACK = LUAI_MAXSTACK;
\ No newline at end of file