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Fix pre-PHP 8.2 compatibility for php_mt_rand_range() with MT_RAND_PHP (#9839)

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* Fix pre-PHP 8.2 compatibility for php_mt_rand_range() with MT_RAND_PHP

As some left-over comments indicated:

> Legacy mode deliberately not inside php_mt_rand_range()
> to prevent other functions being affected

The broken scaler was only used for `php_mt_rand_common()`, not
`php_mt_rand_range()`. The former is only used for `mt_rand()`, whereas the
latter is used for `array_rand()` and others.

With the refactoring for the introduction of ext/random `php_mt_rand_common()`
and `php_mt_rand_range()` were accidentally unified, thus introducing a
behavioral change that was reported in FakerPHP/Faker#528.

This commit moves the checks for `MT_RAND_PHP` from the general-purpose
`range()` function back into `php_mt_rand_common()` and also into
`Randomizer::getInt()` for drop-in compatibility with `mt_rand()`.

* [ci skip] NEWS for `MT_RAND_PHP` compatibility
This commit is contained in:
Tim Düsterhus 2022-10-28 16:52:43 +02:00 • committed by GitHub
parent 0db2e666a5
commit 7f0b228f48
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5 changed files with 68 additions and 19 deletions
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17
ext/random/randomizer.c
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@ -126,7 +126,22 @@ PHP_METHOD(Random_Randomizer, getInt)
RETURN_THROWS();
}
result = randomizer->algo->range(randomizer->status, min, max);
if (UNEXPECTED(
randomizer->algo->range == php_random_algo_mt19937.range
&& ((php_random_status_state_mt19937 *) randomizer->status->state)->mode != MT_RAND_MT19937
)) {
uint64_t r = php_random_algo_mt19937.generate(randomizer->status) >> 1;
/* This is an inlined version of the RAND_RANGE_BADSCALING macro that does not invoke UB when encountering
* (max - min) > ZEND_LONG_MAX.
*/
zend_ulong offset = (double) ( (double) max - min + 1.0) * (r / (PHP_MT_RAND_MAX + 1.0));
result = (zend_long) (offset + min);
} else {
result = randomizer->algo->range(randomizer->status, min, max);
}
if (EG(exception)) {
RETURN_THROWS();
}