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Date: Thu, 21 Jul 2016 01:44:02 +0300
From: Solar Designer <solar@...nwall.com>
To: owl-dev@...ts.openwall.com
Subject: Re: passwdqc code quality

Hi Dmitry,

Thank you for your review and comments!

On Thu, Jul 21, 2016 at 01:09:54AM +0300, Dmitry V. Levin wrote:
> In this particular case, _passwdqc_memzero doesn't look like a good
> addition to libpasswdqc ABI,

Yes.  The underscore suggests it's internal and may be gone later.

> so I'd rather not export it from libpasswdqc at all, e.g.

Your changes mean that there will be separate _passwdqc_memzero pointers
in libpasswdqc, pam_passwdqc, and both programs, and that libpasswdqc's
_passwdqc_memzero couldn't be overridden at runtime by a program using
this library.  This introduces the likelihood of a linker figuring out
that _passwdqc_memzero is always memset, and optimizing it out.  With
my code, the (static) linker may only figure out that _passwdqc_memzero
is often memset, so it can theoretically introduce code to handle this
special case quicker, but that's less likely.

If you still prefer to make these changes despite of what I wrote above,
please feel free to commit them tonight.  I haven't yet made my changes
public, so you do not need to bump the version number.  I'll probably
release this tomorrow.

Alexander

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