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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:35:18 +0000 |
commit | b750101eb236130cf056c675997decbac904cc49 (patch) | |
tree | a5df1a06754bdd014cb975c051c83b01c9a97532 /src/test/test-random-util.c | |
parent | Initial commit. (diff) | |
download | systemd-b750101eb236130cf056c675997decbac904cc49.tar.xz systemd-b750101eb236130cf056c675997decbac904cc49.zip |
Adding upstream version 252.22.upstream/252.22
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/test/test-random-util.c')
-rw-r--r-- | src/test/test-random-util.c | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/src/test/test-random-util.c b/src/test/test-random-util.c new file mode 100644 index 0000000..e597271 --- /dev/null +++ b/src/test/test-random-util.c @@ -0,0 +1,79 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <math.h> + +#include "hexdecoct.h" +#include "log.h" +#include "memory-util.h" +#include "random-util.h" +#include "terminal-util.h" +#include "tests.h" + +TEST(random_bytes) { + uint8_t buf[16] = {}; + + for (size_t i = 1; i < sizeof buf; i++) { + random_bytes(buf, i); + if (i + 1 < sizeof buf) + assert_se(buf[i] == 0); + + hexdump(stdout, buf, i); + } +} + +TEST(crypto_random_bytes) { + uint8_t buf[16] = {}; + + for (size_t i = 1; i < sizeof buf; i++) { + assert_se(crypto_random_bytes(buf, i) == 0); + if (i + 1 < sizeof buf) + assert_se(buf[i] == 0); + + hexdump(stdout, buf, i); + } +} + +#define TOTAL 100000 + +static void test_random_u64_range_one(unsigned mod) { + log_info("/* %s(%u) */", __func__, mod); + + unsigned max = 0, count[mod]; + zero(count); + + for (unsigned i = 0; i < TOTAL; i++) { + uint64_t x; + + x = random_u64_range(mod); + + count[x]++; + max = MAX(max, count[x]); + } + + /* Print histogram: vertical axis — value, horizontal axis — count. + * + * The expected value is always TOTAL/mod, because the distribution should be flat. The expected + * variance is TOTAL×p×(1-p), where p==1/mod, and standard deviation the root of the variance. + * Assert that the deviation from the expected value is less than 6 standard deviations. + */ + unsigned scale = 2 * max / (columns() < 20 ? 80 : columns() - 20); + double exp = (double) TOTAL / mod; + + for (size_t i = 0; i < mod; i++) { + double dev = (count[i] - exp) / sqrt(exp * (mod > 1 ? mod - 1 : 1) / mod); + log_debug("%02zu: %5u (%+.3f)%*s", + i, count[i], dev, + (int) (count[i] / scale), "x"); + + assert_se(fabs(dev) < 6); /* 6 sigma is excessive, but this check should be enough to + * identify catastrophic failure while minimizing false + * positives. */ + } +} + +TEST(random_u64_range) { + for (unsigned mod = 1; mod < 29; mod++) + test_random_u64_range_one(mod); +} + +DEFINE_TEST_MAIN(LOG_DEBUG); |