From eb41999461b6f428186c55abd95f4ce1a76217d5 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 7 Jul 2020 18:03:48 -0300
Subject: Fixed bugs of stack reallocation x GC

Macro 'checkstackGC' was doing a GC step after resizing the stack;
the GC could shrink the stack and undo the resize. Moreover, macro
'checkstackp' also does a GC step, which could remove the preallocated
CallInfo when calling a function. (Its name has been changed to
'checkstackGCp' to emphasize that it calls the GC.)
---
 ldo.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

(limited to 'ldo.c')

diff --git a/ldo.c b/ldo.c
index 66217a4b..e3db1f74 100644
--- a/ldo.c
+++ b/ldo.c
@@ -465,13 +465,13 @@ void luaD_call (lua_State *L, StkId func, int nresults) {
       f = fvalue(s2v(func));
      Cfunc: {
       int n;  /* number of returns */
-      CallInfo *ci = next_ci(L);
-      checkstackp(L, LUA_MINSTACK, func);  /* ensure minimum stack size */
+      CallInfo *ci;
+      checkstackGCp(L, LUA_MINSTACK, func);  /* ensure minimum stack size */
+      L->ci = ci = next_ci(L);
       ci->nresults = nresults;
       ci->callstatus = CIST_C;
       ci->top = L->top + LUA_MINSTACK;
       ci->func = func;
-      L->ci = ci;
       lua_assert(ci->top <= L->stack_last);
       if (L->hookmask & LUA_MASKCALL) {
         int narg = cast_int(L->top - func) - 1;
@@ -485,12 +485,13 @@ void luaD_call (lua_State *L, StkId func, int nresults) {
       break;
     }
     case LUA_VLCL: {  /* Lua function */
-      CallInfo *ci = next_ci(L);
+      CallInfo *ci;
       Proto *p = clLvalue(s2v(func))->p;
       int narg = cast_int(L->top - func) - 1;  /* number of real arguments */
       int nfixparams = p->numparams;
       int fsize = p->maxstacksize;  /* frame size */
-      checkstackp(L, fsize, func);
+      checkstackGCp(L, fsize, func);
+      L->ci = ci = next_ci(L);
       ci->nresults = nresults;
       ci->u.l.savedpc = p->code;  /* starting point */
       ci->callstatus = 0;
@@ -504,7 +505,7 @@ void luaD_call (lua_State *L, StkId func, int nresults) {
       break;
     }
     default: {  /* not a function */
-      checkstackp(L, 1, func);  /* space for metamethod */
+      checkstackGCp(L, 1, func);  /* space for metamethod */
       luaD_tryfuncTM(L, func);  /* try to get '__call' metamethod */
       goto retry;  /* try again with metamethod */
     }
-- 
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