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Clock component removed from 'luaL_makeseed'

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'clock' can be quite slow on some machines.
This commit is contained in:
Roberto Ierusalimschy 2023-03-23 16:01:16 -03:00
parent 5a04f1851e
commit 86e8039a72
4 changed files with 9 additions and 11 deletions
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10
lauxlib.c
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@ -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;
}

4
lmathlib.c
View File

@ -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);

2
ltablib.c
View File

@ -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;
}

4
manual/manual.of
View File

@ -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.)
}