diff options
Diffstat (limited to 'ext/standard/tests/math/bug75170.phpt')
| -rw-r--r-- | ext/standard/tests/math/bug75170.phpt | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/ext/standard/tests/math/bug75170.phpt b/ext/standard/tests/math/bug75170.phpt new file mode 100644 index 0000000000..a9aab06ef4 --- /dev/null +++ b/ext/standard/tests/math/bug75170.phpt @@ -0,0 +1,32 @@ +--TEST-- +Bug #75170: mt_rand() bias on 64-bit machines +--CREDITS-- +Solar Designer in https://externals.io/message/100229 +--FILE-- +<?php + +// PHP pre-7.1.0 modulo bias +mt_srand(1234567890); +$total = 10000; +$max = 0x66666666; +$halves[0] = $halves[1] = 0; +for ($i = 0; $i < $total; $i++) { + $halves[(mt_rand(0, $max - 1) >> 1) & 1]++; +} +printf("%.1f%% vs. %.1f%%\n", 100. * $halves[0] / $total, 100. * $halves[1] / $total); + +// PHP 7.1.0 to 7.2.0beta2 modulo bias bug found during work +// on http://www.openwall.com/php_mt_seed/ +mt_srand(1234567890); +$total = 10000; +$max = 0x66666666; +$halves[0] = $halves[1] = 0; +for ($i = 0; $i < $total; $i++) { + $halves[mt_rand(0, $max - 1) / ($max / 2)]++; +} +printf("%.1f%% vs. %.1f%%\n", 100. * $halves[0] / $total, 100. * $halves[1] / $total); + +?> +--EXPECT-- +49.5% vs. 50.5% +50.5% vs. 49.5% |