lua

commit 1a741157cb43021a90189a2c7019f9323aa6f101
parent 0c78de0d6df13269458d38199f0a8bbe7ce733f2
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date:   Thu,  8 Oct 2015 12:55:09 -0300

avoid (undefined behavior) integer 'overflow' in left shift

Diffstat:
M
lbitlib.c
 | 
9
++++-----

1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/lbitlib.c b/lbitlib.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lbitlib.c,v 1.27 2014/10/01 11:54:56 roberto Exp roberto $
+** $Id: lbitlib.c,v 1.28 2014/11/02 19:19:04 roberto Exp roberto $
 ** Standard library for bitwise operations
 ** See Copyright Notice in lua.h
 */
@@ -186,11 +186,10 @@ static int b_extract (lua_State *L) {
 static int b_replace (lua_State *L) {
   int w;
   lua_Unsigned r = trim(luaL_checkunsigned(L, 1));
-  lua_Unsigned v = luaL_checkunsigned(L, 2);
+  lua_Unsigned v = trim(luaL_checkunsigned(L, 2));
   int f = fieldargs(L, 3, &w);
-  int m = mask(w);
-  v &= m;  /* erase bits outside given width */
-  r = (r & ~(m << f)) | (v << f);
+  lua_Unsigned m = mask(w);
+  r = (r & ~(m << f)) | ((v & m) << f);
   lua_pushunsigned(L, r);
   return 1;
 }