Re: [PATCH v8 2/9] stdlib: Add arc4random tests

[Florian Weimer <fweimer@redhat.com>]

* Adhemerval Zanella:

> The basic tst-arc4random-chacha20.c checks if the output of ChaCha20
> implementation matches the reference test vectors from RFC8439.
> 
> The tst-arc4random-fork.c check if subprocesses generate distinct
> streams of randomness (if fork handling is done correctly).
> 
> The tst-arc4random-stats.c is a statistical test to the randomness of
> arc4random, arc4random_buf, and arc4random_uniform.
> 
> The tst-arc4random-thread.c check if threads generate distinct streams
> of randomness (if function are thread-safe).


Maybe mention in the commit message that the tests are based on a
previous implementation, so the locking and race detection stuff is not
necessarily relevant with the per-thread state?

> --- /dev/null
> +++ b/stdlib/tst-arc4random-chacha20.c
> @@ -0,0 +1,167 @@

> +#include <arc4random.h>
> +#include <support/check.h>
> +#include <sys/cdefs.h>
> +
> +/* The test does not define CHACHA20_XOR_FINAL to mimic what arc4random
> +   actual does. */

Missing space after .

> diff --git a/stdlib/tst-arc4random-fork.c b/stdlib/tst-arc4random-fork.c
> new file mode 100644
> index 0000000000..a7f7fee671
> --- /dev/null
> +++ b/stdlib/tst-arc4random-fork.c
> @@ -0,0 +1,198 @@
> +/* Test that subprocesses generate distinct streams of randomness.
> +   Copyright (C) 2022 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */

http:// instead of https://.  (There are more occurrences.)

> +/* Collect random data from subprocesses and check that all the
> +   results are unique.  */
> +
> +#include <array_length.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/xthread.h>
> +#include <support/xunistd.h>
> +#include <unistd.h>
> +
> +/* Perform multiple runs.  The subsequent runs start with an
> +   already-initialized random number generator.  (The number 1500 was
> +   seen to reproduce failures reliable in case of a race condition in
> +   the fork detection code.)  */
> +enum { runs = 1500 };

Comment is outdated, there is no fork detection code anymore.


> diff --git a/stdlib/tst-arc4random-thread.c b/stdlib/tst-arc4random-thread.c
> new file mode 100644
> index 0000000000..935cdcaf12
> --- /dev/null
> +++ b/stdlib/tst-arc4random-thread.c
> @@ -0,0 +1,341 @@
> +/* Test that threads generate distinct streams of randomness.
> +   Copyright (C) 2018 Free Software Foundation, Inc.

Should be 2022.

Thanks,
Florian