Mesa (master): util/rand_xor: fallback Linux to time-based instead of fixed seed
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Sat May 16 12:25:18 UTC 2020
Module: Mesa
Branch: master
Commit: d76abe98cf15226f25d93e76e383715061ada6f4
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=d76abe98cf15226f25d93e76e383715061ada6f4
Author: Eric Engestrom <eric.engestrom at intel.com>
Date: Sun Oct 13 16:09:22 2019 +0100
util/rand_xor: fallback Linux to time-based instead of fixed seed
When the caller asked for a randomised_seed, we should fall back to the
time-based seed instead of the fixed seed.
Signed-off-by: Eric Engestrom <eric.engestrom at intel.com>
Reviewed-by: Emmanuel Gil Peyrot <linkmauve at linkmauve.fr>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2316>
---
src/util/rand_xor.c | 36 ++++++++++++++----------------------
1 file changed, 14 insertions(+), 22 deletions(-)
diff --git a/src/util/rand_xor.c b/src/util/rand_xor.c
index b486a53343c..3668ac9b84a 100644
--- a/src/util/rand_xor.c
+++ b/src/util/rand_xor.c
@@ -28,10 +28,10 @@
#endif
#include <unistd.h>
#include <fcntl.h>
-#else
-#include <time.h>
#endif
+#include <time.h>
+
#include "rand_xor.h"
/* Super fast random number generator.
@@ -56,8 +56,12 @@ rand_xorshift128plus(uint64_t seed[2])
void
s_rand_xorshift128plus(uint64_t seed[2], bool randomised_seed)
{
- if (!randomised_seed)
- goto fixed_seed;
+ if (!randomised_seed) {
+ /* Use a fixed seed */
+ seed[0] = 0x3bffb83978e24f88;
+ seed[1] = 0x9238d5d56c71cd35;
+ return;
+ }
#if defined(__linux__)
size_t seed_size = sizeof(uint64_t) * 2;
@@ -69,27 +73,15 @@ s_rand_xorshift128plus(uint64_t seed[2], bool randomised_seed)
#endif
int fd = open("/dev/urandom", O_RDONLY);
- if (fd < 0)
- goto fixed_seed;
-
- if (read(fd, seed, seed_size) != seed_size) {
+ if (fd >= 0) {
+ if (read(fd, seed, seed_size) == seed_size) {
+ close(fd);
+ return;
+ }
close(fd);
- goto fixed_seed;
}
-
- close(fd);
- return;
-
-#else
- seed[0] = 0x3bffb83978e24f88;
- seed[1] = time(NULL);
-
- return;
#endif
-fixed_seed:
-
- /* Fallback to a fixed seed */
seed[0] = 0x3bffb83978e24f88;
- seed[1] = 0x9238d5d56c71cd35;
+ seed[1] = time(NULL);
}
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