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From: Khem Raj <raj.khem@gmail.com>
Date: Fri, 23 Mar 2018 01:30:00 -0000
Message-ID: <CAMKF1sqVBx3_8sK=BuH_HRFDLTQqtT9M8t=eSDpOVRyJRAnOkw@mail.gmail.com>
Subject: Re: [PATCH] Replace strncpy with memccpy to fix -Wstringop-truncation.
To: Joseph Myers <joseph@codesourcery.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
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Hi Joseph

On Thu, Mar 22, 2018 at 6:17 PM, Joseph Myers <joseph@codesourcery.com> wrote:
> On Thu, 22 Mar 2018, Khem Raj wrote:
>
>>       * nis/nss_nisplus/nisplus-parser.c: Replace strncpy with memcpy to
>>       avoid -Wstringop-truncation.
>
> Could you give more details of (a) in what circumstances (architecture,
> compiler, etc.) you get this warning and (b) why the truncation is
> correct?
>
> Whatever build failure you got hasn't shown up with build-many-glibcs.py.
> Maybe that should include a configuration with --enable-obsolete-rpc
> --enable-obsolete-nsl to make sure that it tests building those bits of
> code that are disabled by default?
>

This is seen with gcc/trunk when cross compiling for armv7ve target
and yes --enable-obsolete-rpc is used to configure, I am using
OpenEmbedded build system.

nss_nisplus/nisplus-parser.c:90:7: error: 'strncpy' destination
unchanged after copying no bytes [-Werror=stringop-truncation]
       strncpy (first_unused, numstr, len);
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
nss_nisplus/nisplus-parser.c:106:7: error: 'strncpy' destination
unchanged after copying no bytes [-Werror=stringop-truncation]
       strncpy (first_unused, numstr, len);
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~