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bug: __newindex metamethod may not work if metatable is its own

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metatable + luaV_settable does not create entry when there is a
metamethod (and therefore entry is useless)
This commit is contained in:
Roberto Ierusalimschy
2011-08-17 17:26:47 -03:00
parent 166dd0261a
commit 89b59eee73
4 changed files with 44 additions and 26 deletions
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33
lvm.c
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@@ -1,5 +1,5 @@
/*
** $Id: lvm.c,v 2.141 2011/06/09 18:24:22 roberto Exp roberto $
** $Id: lvm.c,v 2.142 2011/08/09 20:58:29 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
@@ -127,29 +127,38 @@ void luaV_gettable (lua_State *L, const TValue *t, TValue *key, StkId val) {
void luaV_settable (lua_State *L, const TValue *t, TValue *key, StkId val) {
int loop;
TValue temp;
for (loop = 0; loop < MAXTAGLOOP; loop++) {
const TValue *tm;
if (ttistable(t)) { /* `t' is a table? */
Table *h = hvalue(t);
TValue *oldval = luaH_set(L, h, key); /* do a primitive set */
if (!ttisnil(oldval) || /* result is not nil? */
(tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL) { /* or no TM? */
setobj2t(L, oldval, val);
TValue *oldval = cast(TValue *, luaH_get(h, key));
/* if previous value is not nil, there must be a previous entry
in the table; moreover, a metamethod has no relevance */
if (!ttisnil(oldval) ||
/* previous value is nil; must check the metamethod */
((tm = fasttm(L, h->metatable, TM_NEWINDEX)) == NULL &&
/* no metamethod; is there a previous entry in the table? */
(oldval != luaO_nilobject ||
/* no previous entry; must create one. (The next test is
always true; we only need the assignment.) */
(oldval = luaH_newkey(L, h, key), 1)))) {
/* no metamethod and (now) there is an entry with given key */
setobj2t(L, oldval, val); /* assign new value to that entry */
invalidateTMcache(h);
luaC_barrierback(L, obj2gco(h), val);
return;
}
/* else will try the tag method */
/* else will try the metamethod */
}
else if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
luaG_typeerror(L, t, "index");
else /* not a table; check metamethod */
if (ttisnil(tm = luaT_gettmbyobj(L, t, TM_NEWINDEX)))
luaG_typeerror(L, t, "index");
/* there is a metamethod */
if (ttisfunction(tm)) {
callTM(L, tm, t, key, val, 0);
return;
}
/* else repeat with 'tm' */
setobj(L, &temp, tm); /* avoid pointing inside table (may rehash) */
t = &temp;
t = tm; /* else repeat with 'tm' */
}
luaG_runerror(L, "loop in settable");
}