bug: 'random' limit is 2^31-1, not RAND_MAX

lmathlib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lmathlib.c,v 1.112 2014/11/02 19:19:04 roberto Exp roberto $
+** $Id: lmathlib.c,v 1.113 2014/11/07 11:31:58 roberto Exp roberto $
 ** Standard mathematical library
 ** See Copyright Notice in lua.h
 */
@@ -27,9 +27,11 @@
 #if defined(LUA_USE_POSIX)
 #define l_rand()	random()
 #define l_srand(x)	srandom(x)
+#define L_RANDMAX	2147483647	/* (2^31 - 1), following POSIX */
 #else
 #define l_rand()	rand()
 #define l_srand(x)	srand(x)
+#define L_RANDMAX	RAND_MAX
 #endif
 #endif				/* } */
 
@@ -233,12 +235,12 @@ static int math_max (lua_State *L) {
 
 /*
 ** This function uses 'double' (instead of 'lua_Number') to ensure that
-** all bits from 'l_rand' can be represented, and that 'RAND_MAX + 1.0'
+** all bits from 'l_rand' can be represented, and that 'RANDMAX + 1.0'
 ** will keep full precision (ensuring that 'r' is always less than 1.0.)
 */
 static int math_random (lua_State *L) {
   lua_Integer low, up;
-  double r = (double)l_rand() * (1.0 / ((double)RAND_MAX + 1.0));
+  double r = (double)l_rand() * (1.0 / ((double)L_RANDMAX + 1.0));
   switch (lua_gettop(L)) {  /* check number of arguments */
     case 0: {  /* no arguments */
       lua_pushnumber(L, (lua_Number)r);  /* Number between 0 and 1 */