commit 86e8039a72646cd9192fd08a6f1771c90b872ff6
parent 5a04f1851e0d42b4bcbb0af103490bc964e985aa
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 23 Mar 2023 16:00:49 -0300
Clock component removed from 'luaL_makeseed'
'clock' can be quite slow on some machines.
Diffstat:
4 files changed, 9 insertions(+), 11 deletions(-)
diff --git a/lauxlib.c b/lauxlib.c
@@ -1094,8 +1094,8 @@ static void warnfon (void *ud, const char *message, int tocont) {
/*
** A function to compute an unsigned int with some level of
-** randomness. Rely on Address Space Layout Randomization (if present),
-** current time, and clock.
+** randomness. Rely on Address Space Layout Randomization (if present)
+** and the current time.
*/
#if !defined(luai_makeseed)
@@ -1115,18 +1115,16 @@ static void warnfon (void *ud, const char *message, int tocont) {
static unsigned int luai_makeseed (void) {
- unsigned int buff[sof(void*) + sof(clock_t) + sof(time_t)];
+ unsigned int buff[sof(void*) + sof(time_t)];
unsigned int res;
unsigned int *b = buff;
- clock_t c = clock();
time_t t = time(NULL);
void *h = buff;
addbuff(b, h); /* local variable's address */
- addbuff(b, c); /* clock */
addbuff(b, t); /* time */
res = buff[0];
for (b = buff + 1; b < buff + sof(buff); b++)
- res += *b;
+ res ^= (res >> 3) + (res << 7) + *b;
return res;
}
diff --git a/lmathlib.c b/lmathlib.c
@@ -607,8 +607,8 @@ static int math_randomseed (lua_State *L) {
RanState *state = (RanState *)lua_touserdata(L, lua_upvalueindex(1));
lua_Unsigned n1, n2;
if (lua_isnone(L, 1)) {
- n1 = luaL_makeseed(L);
- n2 = I2UInt(state->s[0]);
+ n1 = luaL_makeseed(L); /* "random" seed */
+ n2 = I2UInt(nextrand(state->s)); /* in case seed is not that random... */
}
else {
n1 = luaL_checkinteger(L, 1);
diff --git a/ltablib.c b/ltablib.c
@@ -310,7 +310,7 @@ static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
*/
static IdxT choosePivot (IdxT lo, IdxT up, unsigned int rnd) {
IdxT r4 = (up - lo) / 4; /* range/4 */
- IdxT p = rnd % (r4 * 2) + (lo + r4);
+ IdxT p = (rnd ^ lo ^ up) % (r4 * 2) + (lo + r4);
lua_assert(lo + r4 <= p && p <= up - r4);
return p;
}
diff --git a/manual/manual.of b/manual/manual.of
@@ -5728,8 +5728,8 @@ it does not run it.
@apii{0,0,-}
Returns a value with a weak attempt for randomness.
-(It produces that value based on the current date and time,
-the current processor time, and the address of an internal variable,
+(It produces that value based on the current date and time
+and the address of an internal variable,
in case the machine has Address Space Layout Randomization.)
}