From: Jonathan Wakely <jwakely@redhat.com>
To: Alexandre Oliva <oliva@adacore.com>
Cc: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: Re: require et random_device for cons token test
Date: Thu, 25 Mar 2021 11:57:43 +0000 [thread overview]
Message-ID: <20210325115743.GM3008@redhat.com> (raw)
In-Reply-To: <ory2eb7d1k.fsf@lxoliva.fsfla.org>
On 25/03/21 07:17 -0300, Alexandre Oliva wrote:
>On Mar 24, 2021, Jonathan Wakely <jwakely@redhat.com> wrote:
>
>> This works for me on x86_64-linux and powerpc64le-linux, and also on
>> x86_64-linux when I kluge the config macros so that the new code path
>> gets used. Does this work for VxWorks?
>
>Thanks. I (trivially) backported it to apply on our gcc-10 tree, and
>tested that on x86_64-vx7r2, and I confirm it works there too.
>
>However, I suspect there's a series of typos in the patch. You appear
>to be using the 'which' enum variable for bit testing, but with '|'
>rather than '&'.
Oops, that's what I get for a last-minute rewrite without proper
testing. I originally had:
if (which == blah || which == any)
and then borked it in an attempt to use & instead.
I'll fix that locally too.
>Unless I'm missing something in my reading of the modified code, this
>may cause a backend different from that requested by the token to be
>selected, but it doesn't look like we have any test that detects this
>problem.
I don't see how it's possible to detect, without something like a
modified system that replaces /dev/random with a non-random source so
you can verify that std::random_device("/dev/random") and
std::random_device("rdseed") don't use the same source.
I suppose we could check the number of open file descriptors as a proxy
for "something is reading /dev/random", but there's no way to check
that std::random_device(tok1) and std::random_device(tok2) use
different sources of randomness.
next prev parent reply other threads:[~2021-03-25 11:58 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-24 6:53 Alexandre Oliva
2021-03-24 8:59 ` Jonathan Wakely
2021-03-24 10:33 ` Alexandre Oliva
2021-03-24 11:27 ` Jonathan Wakely
2021-03-24 14:01 ` Jonathan Wakely
2021-03-25 10:17 ` Alexandre Oliva
2021-03-25 11:57 ` Jonathan Wakely [this message]
2021-03-26 19:17 ` Jonathan Wakely
2021-03-25 11:03 ` Alexandre Oliva
2021-03-25 11:39 ` Jonathan Wakely
2021-03-25 11:00 ` Alexandre Oliva
2021-03-25 11:38 ` Jonathan Wakely
2021-11-09 15:02 ` Jonathan Wakely
2021-03-24 10:55 ` Jonathan Wakely
2021-03-24 13:22 ` Koning, Paul
2021-03-24 13:38 ` Jonathan Wakely
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