From: Alejandro Colomar <alx.manpages@gmail.com>
To: Jonny Grant <jg@jguk.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>,
linux-man <linux-man@vger.kernel.org>,
GNU C Library <libc-alpha@sourceware.org>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH] Add example to rand.3
Date: Wed, 28 Dec 2022 22:32:17 +0100 [thread overview]
Message-ID: <972c5604-ff05-43c6-ec8d-edda8f8d885b@gmail.com> (raw)
In-Reply-To: <558d5ceb-a35e-d990-c9c8-72a7a7784d4c@jguk.org>
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Hi,
On 12/28/22 22:25, Jonny Grant wrote:
> That example program looks good, thank you for taking the time to prepare that patch.
> Jonny
Thanks!
This is my v2:
It doesn't recommend libbsd's arc4random().
It also shows that arc4random is just a way to get a random seed, and prints it,
but then it's as "bad" as any other run of srand(3) + rand(3).
Cheers,
Alex
diff --git a/man3/rand.3 b/man3/rand.3
index 572471749..08ad0a822 100644
--- a/man3/rand.3
+++ b/man3/rand.3
@@ -190,6 +190,9 @@ .SH EXAMPLES
pseudo-random sequence produced by
.BR rand ()
when given a particular seed.
+When the seed is
+.IR \-1 ,
+the program uses a random seed.
.PP
.in +4n
.\" SRC BEGIN (rand.c)
@@ -211,7 +214,13 @@ .SH EXAMPLES
seed = atoi(argv[1]);
nloops = atoi(argv[2]);
+ if (seed == -1) {
+ seed = arc4random();
+ printf("seed: %u\en", seed);
+ }
+
srand(seed);
+
for (unsigned int j = 0; j < nloops; j++) {
r = rand();
printf("%d\en", r);
--
<http://www.alejandro-colomar.es/>
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next prev parent reply other threads:[~2022-12-28 21:32 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <105835f5-359c-2646-f609-e73459ee2d3b@jguk.org>
2022-12-26 22:29 ` Alejandro Colomar
2022-12-27 13:07 ` Cristian Rodríguez
2022-12-27 23:33 ` Alejandro Colomar
2022-12-28 0:00 ` G. Branden Robinson
2022-12-28 0:41 ` Alejandro Colomar
2022-12-28 12:21 ` Cristian Rodríguez
2022-12-30 18:15 ` Joseph Myers
2022-12-30 18:20 ` Alejandro Colomar
2022-12-30 18:50 ` Joseph Myers
2022-12-30 18:58 ` Alejandro Colomar
2022-12-30 19:11 ` Cristian Rodríguez
2022-12-30 21:08 ` Joseph Myers
2022-12-30 21:15 ` Internal organization of "the implementation" (was: [PATCH] Add example to rand.3) Alejandro Colomar
2022-12-30 21:50 ` Joseph Myers
2022-12-27 21:37 ` [PATCH] Add example to rand.3 Jonny Grant
2022-12-27 23:11 ` Alejandro Colomar
2022-12-28 20:51 ` Jonny Grant
2022-12-28 20:56 ` Alejandro Colomar
2022-12-28 21:03 ` Alejandro Colomar
2022-12-28 21:04 ` Alejandro Colomar
2022-12-28 21:25 ` Jonny Grant
2022-12-28 21:32 ` Alejandro Colomar [this message]
2022-12-28 21:04 ` Cristian Rodríguez
2022-12-28 21:11 ` Alejandro Colomar
2022-12-28 21:19 ` Jonny Grant
2022-12-28 21:18 ` Alejandro Colomar
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