From: Peter Mamonov <pmamonov@gmail.com>
To: barebox@lists.infradead.org
Subject: Re: command: hashsum: md5sum reports wrong sum for the file named 4k.bin
Date: Thu, 21 Dec 2017 13:48:11 +0300 [thread overview]
Message-ID: <20171221104811.3o2tesuqfr7ej477@localhost.localdomain> (raw)
In-Reply-To: <20171220104814.4snxmloobeywnuwb@localhost.localdomain>
On Wed, Dec 20, 2017 at 01:48:14PM +0300, Peter Mamonov wrote:
> Hi,
>
> The md5sum command reports wrong sum for a file named 4k.bin and, I guess, for
> other files named alike. Here are the commands to reproduce the bug:
The problem lays in __do_digest() function:
- it initializes variables `start` and `size` at commands/digest.c:38
- then it calls parse_area_spec(*argv, &start, &size) at commands/digest.c:42
- parse_area_spec() returns error as it should, however it changes the value
of the `start` at lib/misc.c:87.
- this causes digest algo to skip leading 4k of the data from the file.
I'm not quite sure what is the best solution:
- prevent parse_area_spec() from setting start if it fails?
- reinitialize start/size after unsuccessfull call to parse_area_spec()?
Regards,
Peter
>
> barebox@barebox sandbox:/ memcpy -s /dev/zero -d _4k.bin 0 0 4k
> barebox@barebox sandbox:/ md5sum _4k.bin
> 620f0b67a91f7f74151bc5be745b7110 _4k.bin
>
> barebox@barebox sandbox:/ cp _4k.bin 4k.bin
> barebox@barebox sandbox:/ md5sum 4k.bin
> d41d8cd98f00b204e9800998ecf8427e 4k.bin
>
> barebox@barebox sandbox:/ cp 4k.bin __4k.bin
> barebox@barebox sandbox:/ md5sum __4k.bin
> 620f0b67a91f7f74151bc5be745b7110 __4k.bin
>
> barebox@barebox sandbox:/ version
>
> barebox 2017.12.0 #4 Wed Dec 20 12:26:57 MSK 2017
>
> barebox@barebox sandbox:/ Terminated
>
> $ dd if=/dev/zero bs=4k count=1 | md5sum
> ...
> 620f0b67a91f7f74151bc5be745b7110 -
>
> Regards,
> Peter
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
next prev parent reply other threads:[~2017-12-21 10:48 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-20 10:48 Peter Mamonov
2017-12-21 10:48 ` Peter Mamonov [this message]
2018-01-05 11:44 ` Sascha Hauer
2018-01-05 18:17 ` Peter Mamonov
2018-01-09 11:10 ` Sascha Hauer
2018-01-09 14:21 ` [PATCH] lib: parse_area_spec: don't modify *start and *size values if parse failed Peter Mamonov
2018-01-11 8:15 ` Sascha Hauer
2018-01-11 17:28 ` Peter Mamonov
2018-01-15 11:32 ` [PATCH v2 1/3] lib: parse_area_spec: don't modify *start value " Peter Mamonov
2018-01-15 11:32 ` [PATCH v2 2/3] lib: parse_area_spec: part of the area spec after -/+ should start with a digit Peter Mamonov
2018-01-15 11:32 ` [PATCH v2 3/3] lib: parse_area_spec: no extra symbols after area spec are allowed except for spaces Peter Mamonov
2018-01-17 8:11 ` [PATCH v2 1/3] lib: parse_area_spec: don't modify *start value if parse failed Sascha Hauer
2018-01-17 9:31 ` Peter Mamonov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171221104811.3o2tesuqfr7ej477@localhost.localdomain \
--to=pmamonov@gmail.com \
--cc=barebox@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox