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BUG: compiler can optimize away overflow check in 'table.unpack'

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Roberto Ierusalimschy 2014-05-07 13:32:55 -03:00
parent a29377972f
commit 8efe9f23fa
1 changed files with 6 additions and 4 deletions
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10
ltablib.c
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@ -1,10 +1,11 @@
/*
** $Id: ltablib.c,v 1.65 2013/03/07 18:17:24 roberto Exp $
** $Id: ltablib.c,v 1.65.1.1 2013/04/12 18:48:47 roberto Exp roberto $
** Library for Table Manipulation
** See Copyright Notice in lua.h
*/
#include <limits.h>
#include <stddef.h>
#define ltablib_c
@ -134,13 +135,14 @@ static int pack (lua_State *L) {
static int unpack (lua_State *L) {
int i, e, n;
int i, e;
unsigned int n;
luaL_checktype(L, 1, LUA_TTABLE);
i = luaL_optint(L, 2, 1);
e = luaL_opt(L, luaL_checkint, 3, luaL_len(L, 1));
if (i > e) return 0; /* empty range */
n = e - i + 1; /* number of elements */
if (n <= 0 || !lua_checkstack(L, n)) /* n <= 0 means arith. overflow */
n = (unsigned int)e - (unsigned int)i; /* number of elements minus 1 */
if (n > (INT_MAX - 10) || !lua_checkstack(L, ++n))
return luaL_error(L, "too many results to unpack");
lua_rawgeti(L, 1, i); /* push arg[i] (avoiding overflow problems) */
while (i++ < e) /* push arg[i + 1...e] */