Received: (at 29311) by debbugs.gnu.org; 16 Nov 2017 00:14:14 +0000 From debbugs-submit-bounces <at> debbugs.gnu.org Wed Nov 15 19:14:14 2017 Received: from localhost ([127.0.0.1]:42317 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>) id 1eF7or-0001T7-Vk for submit <at> debbugs.gnu.org; Wed, 15 Nov 2017 19:14:14 -0500 Received: from mail-wm0-f68.google.com ([74.125.82.68]:42898) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from <s3gmentationfault@HIDDEN>) id 1eF73B-0006qK-1h for 29311 <at> debbugs.gnu.org; Wed, 15 Nov 2017 18:24:57 -0500 Received: by mail-wm0-f68.google.com with SMTP id t139so6182900wmt.1 for <29311 <at> debbugs.gnu.org>; Wed, 15 Nov 2017 15:24:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:from:subject:message-id:date:user-agent:mime-version :content-transfer-encoding:content-language; bh=99pA5y6lcqWWHf3Eodxp2Rm7c/WUHnljnngh4ekhBFg=; b=RTZGIrqakwTRJu5J+P+U2/aH8uiW+wfmmJoKY3fi4gOJZiFTK8sH8A4vefQLfqKYcX CkziFP6RRrCtLX1l2iV76qccxTtnbLN4TEbcXDAImnr9yXmR0WGanECqaubjzw4Vzy+K Ns70EgmH7Mz24Yoq3tLWKjBDiGAdPvJe8KrOYj2RJ+93o1YDYJ6+jdOXWfzoJcy/uRXQ OyfgQrI4FHfRG5I1tqYhWdbp0GBsunD/UsTIt7rHXVmWGaJYexOq0KGgHNnbFwj4k0xK 3piqXldKWzGrVwR7Zk4q68SSLUUGj5g2lq3w3Sy405DcTw7x9OzXWfPS9OnBkZVYtIPl c7Vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:from:subject:message-id:date:user-agent :mime-version:content-transfer-encoding:content-language; bh=99pA5y6lcqWWHf3Eodxp2Rm7c/WUHnljnngh4ekhBFg=; b=IJB55Dbw0NB1hq7u2bdJepSI2f/MvIZRXnJwrPsu6nBt2Lqr4IhSsKldRlrB3Fs1Nt /2kRZa2QEtHAQ2VMlTHm0rzo99LRxRbKCLg1UUsWcjtVqEh/AEcur/aFeWM4UCHl1CPg M3KDTEIJ0gIvOsX7NzGXY824IEg6hzDyks9+IbyvJvnXNKRY/p0JzaGgyp4Jb0XdsWDB 1sUVue1RUda/FdmGvpljt9rMvh872cwD0SNBMnUd5uaYjX1qSoPRwAJDonj7Lyjq+YO4 oRznem/wRSs6TnTD2OID0N0I1KSpKcTE3FlyWX7Pol09tIfbGoFErdAdvNam9fO1RZ6d +3Vg== X-Gm-Message-State: AJaThX5QY6Xp07lgmhkgr4E9lBXYJkqI1i3fJeNsbG+xEq6tM1FKtet8 mnf621KNeXYkPcZyYxZO/Ex33lYA X-Google-Smtp-Source: AGs4zMa7RS6Ahtpl7Sao/Q93CyfTPe1Iau279RRSLgMiHJozz7y6cX/N6nIqZsVzBWfIlS8ikfWDjw== X-Received: by 10.80.244.16 with SMTP id r16mr95537edm.26.1510788290839; Wed, 15 Nov 2017 15:24:50 -0800 (PST) Received: from [192.168.1.14] ([151.41.10.36]) by smtp.gmail.com with ESMTPSA id j8sm32177edh.55.2017.11.15.15.24.49 for <29311 <at> debbugs.gnu.org> (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 15 Nov 2017 15:24:50 -0800 (PST) To: 29311 <at> debbugs.gnu.org From: "s3gmentationfault@HIDDEN" <s3gmentationfault@HIDDEN> Subject: Byte comparison from cmp diffutils Message-ID: <ab0d7896-b73c-e2d9-9675-2b38794e5615@HIDDEN> Date: Thu, 16 Nov 2017 00:24:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Spam-Score: -0.0 (/) X-Debbugs-Envelope-To: 29311 X-Mailman-Approved-At: Wed, 15 Nov 2017 19:14:12 -0500 X-BeenThere: debbugs-submit <at> debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: <debbugs-submit.debbugs.gnu.org> List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe> List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/> List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org> List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help> List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe> Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org> X-Spam-Score: -0.0 (/) Hi, i write this message regarding to my previous bug report, i have see just now that posix section of manpages say: "The cmp utility shall write no output files are the same. Under default options, if they differ, it shall write tostandard output the byte and line number at which the first difference occurred. Bytes and lines shall be numbered beginning with 1." so now it's all clare.
bug-diffutils@HIDDEN:bug#29311; Package diffutils.
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From: "s3gmentationfault@HIDDEN" <s3gmentationfault@HIDDEN>
Subject: Byte comparison from cmp diffutils
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Hi, i write this message because cmp command from diffutils give an
unexpected result if is used on binary files:
if we try to compare two different files (not symlink, not hardlink
etc..), cmp say that the differ from 42 byte.
~ > LC_ALL=C cmp /usr/bin/g++ /usr/bin/gcc
/usr/bin/g++ /usr/bin/gcc differ: char 42, line 1
During a discussion another member convinced me to try hexdump for do
that comparison than i have see that those file differ for many bytes
then 42, so i have try to write a program for do that, just for sure
(the program is silly i have also forget to return EXIT_SUCCESS, and as
default if it find a different byte the consider all other byte
different but is only for this demonstration)
src: https://arin.ga/swsNn1
~ > CFLAGS=-O3 make diffbyte_gcc && ./diffbyte_gcc
they diff by: 766087 byte
so something absolutely does not work:
some clarifications: I have see just now that using C as language it say
char, but in my language it say "byte" ("/bin/g++ /bin/gcc differenza:
byte 42, riga 1").
However that is indifferent since in manpage it use only "byte" term, so
i expect that it compare bytes, not only ascii text; The manpages at
description say: "Compare two files byte by byte".
For do other example, the wc command with -c option really counts the bytes:
~ > printf "\u2592"|wc -c
3
~ > printf "ciao\0x8" | wc -c
7
and (except for the sparse files) also du and wc report the same result
with binary files:
~ > du -b /bin/gcc
993584 /bin/gcc
~ > wc -c /bin/gcc
993584 /bin/gcc
From info i read:
The 'cmp' command compares two files, and if they differ, tells the
first byte and line number where they differ or reports that one file is
a prefix of the other.
Bytes and lines are numbered starting with 1. The arguments of 'cmp' are
as follows:
I do not know if it is meant that the comparison stops at the first line
or rather when one of the two buffers differs from the other but
manpages and program options say that it compare byte
so it should do
"s3gmentationfault@HIDDEN" <s3gmentationfault@HIDDEN>:bug-diffutils@HIDDEN.
Full text available.bug-diffutils@HIDDEN:bug#29311; Package diffutils.
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