PHP RFC: Move RNG functions ext/random

• Version: 1.0
• Date: 2021-09-07
• Author: Go Kudo zeriyoshi@gmail.com
• Status: Draft

This is due to the historical background, starting with lcg.c / php_lcg.h, the first implementation of the linear congruential generator (LCG), followed by rand.c / php_rand.c, which calls the libc random number implementation, and the Mersenne Twister implementation. mt_rand.c / php_mt_rand.h, an implementation of the Mersenne Twister, and random.c / php_random.h, a CSPRNG implementation, respectively, in the ext/standard extension.

The rand.c / php_rand.h to call the libc implementation is no longer relevant due to its alias to the Mersenne Twister in PHP 7.1, and is left for compatibility only.

RNGs are a frequently used feature in various implementations, and it is suggested that RNG-related functionality be carved out of the ext/standard extension and kindly made into an ext/random extension to reduce complexity and allow for future extensibility.

Create a new ext/random extension and move all the following functions of the ext/standard extension.

Userland Functions:

• lcg_value()
• srand()
• rand()
• mt_srand()
• mt_rand()
• random_int()
• random_bytes()

Internal APIs:

• php_random_int_throw()
• php_random_int_silent()
• php_combined_lcg()
• php_srand()
• php_rand()
• php_mt_srand()
• php_mt_rand()
• php_mt_rand_range()
• php_mt_rand_common()
• php_random_bytes()
• php_random_int()

These features are provided in a single random.c / php_random.h, and ext/random is always bundled with all builds of PHP, as is ext/standard.

Will cause a BC Break for extensions and php-src downstream projects, Means that the following workaround needs to be done to support PHP 8.2 and later.

#if PHP_VERSION_ID >= 80200
#include "ext/random/php_random.h"
#else
#include "ext/standard/php_lcg.h"
#include "ext/standard/php_rand.h"
#include "ext/standard/php_mt_rand.h"
#include "ext/standard/php_random.h"
#endif

In general, BC Breaks should be avoided and, as we have done in the past, BC Breaks should not occur unnecessarily.

However, there is now a need to sort these out in order to deal with other problems with PHP random numbers. I think this could be a good reason to allow this BC Break.

See the relevant PHP RFC: Random Extension 3.0 and Internals ML (or the relevant thread in externals) for details.

There are no disruptive changes to userland. However, there will be a BC Break in the downstream project.

PHP 8.2

none

Will need to change the including header file.

none

none

none

none

https://github.com/php/php-src/pull/7473

https://github.com/php/php-src/pull/7473

https://externals.io/message/115918 https://wiki.php.net/rfc/rng_extension