Fix lua_checkstack to check against LUAI_MAXSTACK. Adds luaD_growstack and luaD_reallocstack

3 files changed, 43 insertions, 1 deletions

diff --git a/src/lapi.js b/src/lapi.js
index cea0568..79c666c 100644
--- a/src/lapi.js
+++ b/src/lapi.js
@@ -91,8 +91,20 @@ const index2addr_ = function(L, idx) {
 };
 
 const lua_checkstack = function(L, n) {
+    let res;
     let ci = L.ci;
-    let res = L.stack.length < luaconf.LUAI_MAXSTACK;
+    assert(n >= 0, "negative 'n'");
+    if (L.stack.length - L.top > n) /* stack large enough? */
+        res = true;
+    else { /* no; need to grow stack */
+        let inuse = L.top + lstate.EXTRA_STACK;
+        if (inuse > luaconf.LUAI_MAXSTACK - n)  /* can grow without overflow? */
+            res = false;  /* no */
+        else { /* try to grow stack */
+            ldo.luaD_growstack(L, n);
+            res = true;
+        }
+    }
 
     if (res && ci.top < L.top + n)
         ci.top = L.top + n;  /* adjust frame top */
diff --git a/src/ldo.js b/src/ldo.js
index eb8df06..1036ce5 100644
--- a/src/ldo.js
+++ b/src/ldo.js
@@ -13,6 +13,7 @@ const lparser = require('./lparser.js');
 const lstate  = require('./lstate.js');
 const lstring = require('./lstring.js');
 const ltm     = require('./ltm.js');
+const luaconf = require('./luaconf.js');
 const lundump = require('./lundump.js');
 const lvm     = require('./lvm.js');
 const lzio    = require('./lzio.js');
@@ -38,6 +39,30 @@ const seterrorobj = function(L, errcode, oldtop) {
     L.top = oldtop + 1;
 };
 
+const ERRORSTACKSIZE = luaconf.LUAI_MAXSTACK + 200;
+
+const luaD_reallocstack = function(L, newsize) {
+    L.stack.length = newsize;
+};
+
+const luaD_growstack = function(L, n) {
+    let size = L.stack.length;
+    if (size > luaconf.LUAI_MAXSTACK)
+        luaD_throw(L, TS.LUA_ERRERR);
+    else {
+        let needed = L.top + n + lstate.EXTRA_STACK;
+        let newsize = 2 * size;
+        if (newsize > luaconf.LUAI_MAXSTACK) newsize = luaconf.LUAI_MAXSTACK;
+        if (newsize < needed) newsize = needed;
+        if (newsize > luaconf.LUAI_MAXSTACK) {  /* stack overflow? */
+            luaD_reallocstack(L, ERRORSTACKSIZE);
+            ldebug.luaG_runerror(L, "stack overflow");
+        }
+        else
+            luaD_reallocstack(L, newsize);
+    }
+};
+
 /*
 ** Prepares a function call: checks the stack, creates a new CallInfo
 ** entry, fills in the relevant information, calls hook if needed.
@@ -594,12 +619,14 @@ module.exports.SParser              = SParser;
 module.exports.adjust_varargs       = adjust_varargs;
 module.exports.luaD_call            = luaD_call;
 module.exports.luaD_callnoyield     = luaD_callnoyield;
+module.exports.luaD_growstack       = luaD_growstack;
 module.exports.luaD_hook            = luaD_hook;
 module.exports.luaD_pcall           = luaD_pcall;
 module.exports.luaD_poscall         = luaD_poscall;
 module.exports.luaD_precall         = luaD_precall;
 module.exports.luaD_protectedparser = luaD_protectedparser;
 module.exports.luaD_rawrunprotected = luaD_rawrunprotected;
+module.exports.luaD_reallocstack    = luaD_reallocstack;
 module.exports.luaD_throw           = luaD_throw;
 module.exports.lua_isyieldable      = lua_isyieldable;
 module.exports.lua_resume           = lua_resume;
diff --git a/src/lstate.js b/src/lstate.js
index 5a65c12..d1789e8 100644
--- a/src/lstate.js
+++ b/src/lstate.js
@@ -14,6 +14,8 @@ const CT                   = defs.constant_types;
 const TS                   = defs.thread_status;
 const LUA_NUMTAGS          = defs.LUA_NUMTAGS;
 
+const EXTRA_STACK = 5;
+
 const BASIC_STACK_SIZE = 2 * defs.LUA_MINSTACK;
 
 class CallInfo {
@@ -200,6 +202,7 @@ module.exports.CIST_TAIL       = (1<<5);  /* call was tail called */
 module.exports.CIST_HOOKYIELD  = (1<<6);  /* last hook called yielded */
 module.exports.CIST_LEQ        = (1<<7);  /* using __lt for __le */
 module.exports.CIST_FIN        = (1<<8);   /* call is running a finalizer */
+module.exports.EXTRA_STACK     = EXTRA_STACK;
 module.exports.lua_close       = lua_close;
 module.exports.lua_newstate    = lua_newstate;
 module.exports.lua_newthread   = lua_newthread;