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author | Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> | 2021-03-26 20:22:29 +0100 |
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committer | GitHub <noreply@github.com> | 2021-03-26 20:22:29 +0100 |
commit | a81c7ac8d408a2618d488e708b40530bcdad6bd1 (patch) | |
tree | 57dc9780c9c3fad33e0a4779101a75bdac6ab324 | |
parent | a9dd1010f0405e85e3b041ee983fcefca5e06895 (diff) | |
parent | f2a8b8decfa3a5281047ad4542a48435302e2253 (diff) | |
download | systemd-a81c7ac8d408a2618d488e708b40530bcdad6bd1.tar.gz |
Merge pull request #19129 from keszybz/test-random-range
Test random_u64_range()
-rw-r--r-- | src/basic/log.h | 2 | ||||
-rw-r--r-- | src/test/test-random-util.c | 64 |
2 files changed, 57 insertions, 9 deletions
diff --git a/src/basic/log.h b/src/basic/log.h index 52fd58d5b4..b3d32abfc8 100644 --- a/src/basic/log.h +++ b/src/basic/log.h @@ -216,7 +216,7 @@ int log_emergency_level(void); #define log_error_errno(error, ...) log_full_errno(LOG_ERR, error, __VA_ARGS__) #define log_emergency_errno(error, ...) log_full_errno(log_emergency_level(), error, __VA_ARGS__) -#ifdef LOG_TRACE +#if LOG_TRACE # define log_trace(...) log_debug(__VA_ARGS__) #else # define log_trace(...) do {} while (0) diff --git a/src/test/test-random-util.c b/src/test/test-random-util.c index 02a73ecdb2..44103efa62 100644 --- a/src/test/test-random-util.c +++ b/src/test/test-random-util.c @@ -1,17 +1,20 @@ /* SPDX-License-Identifier: LGPL-2.1-or-later */ +#include <math.h> + #include "hexdecoct.h" -#include "random-util.h" #include "log.h" +#include "memory-util.h" +#include "random-util.h" +#include "terminal-util.h" #include "tests.h" static void test_genuine_random_bytes(RandomFlags flags) { uint8_t buf[16] = {}; - unsigned i; log_info("/* %s */", __func__); - for (i = 1; i < sizeof buf; i++) { + for (size_t i = 1; i < sizeof buf; i++) { assert_se(genuine_random_bytes(buf, i, flags) == 0); if (i + 1 < sizeof buf) assert_se(buf[i] == 0); @@ -22,11 +25,10 @@ static void test_genuine_random_bytes(RandomFlags flags) { static void test_pseudo_random_bytes(void) { uint8_t buf[16] = {}; - unsigned i; log_info("/* %s */", __func__); - for (i = 1; i < sizeof buf; i++) { + for (size_t i = 1; i < sizeof buf; i++) { pseudo_random_bytes(buf, i); if (i + 1 < sizeof buf) assert_se(buf[i] == 0); @@ -36,9 +38,11 @@ static void test_pseudo_random_bytes(void) { } static void test_rdrand(void) { - int r, i; + int r; + + log_info("/* %s */", __func__); - for (i = 0; i < 10; i++) { + for (unsigned i = 0; i < 10; i++) { unsigned long x = 0; r = rdrand(&x); @@ -51,6 +55,50 @@ static void test_rdrand(void) { } } +#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); + + log_trace("%05u: %"PRIu64, i, x); + 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, + 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. */ + } +} + +static void test_random_u64_range(void) { + for (unsigned mod = 1; mod < 29; mod++) + test_random_u64_range_one(mod); +} + int main(int argc, char **argv) { test_setup_logging(LOG_DEBUG); @@ -61,8 +109,8 @@ int main(int argc, char **argv) { test_genuine_random_bytes(RANDOM_ALLOW_INSECURE); test_pseudo_random_bytes(); - test_rdrand(); + test_random_u64_range(); return 0; } |