From: Alejandro Colomar <alx@kernel.org>
To: Jonny Grant <jg@jguk.org>
Cc: Matthew House <mattlloydhouse@gmail.com>,
linux-man <linux-man@vger.kernel.org>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: strncpy clarify result may not be null terminated
Date: Thu, 9 Nov 2023 13:43:21 +0100 [thread overview]
Message-ID: <ZUzT6SpgjyzkMCYN@debian> (raw)
In-Reply-To: <ZUzEw2j6gHF5WtsO@debian>
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On Thu, Nov 09, 2023 at 12:38:37PM +0100, Alejandro Colomar wrote:
> If you would want to write something based on Michael Kerrisk's article,
> you could do this:
>
> ssize_t
> strxcpy(char *restrict dst, char *restrict src, size_t dsize)
> {
> if (strlen(src) < dsize)
Heh, here's my off-by-one bug of the day. Good thing is I can fix it in
a single place; unlike calling strncpy(3) all the time.
This should have been <=.
Cheers,
Alex
> return -1;
>
> strcpy(dst, src);
> }
>
> You may also want to calculate 'dsize' automagically, to avoid human
> error, in case it's an array, so you could write a macro on top of it:
>
> #define STRXCPY(dst, src) strxcpy(dst, src, ARRAY_SIZE(dst))
>
> These are just small wrappers over standard functions, so you shouldn't
> have problems adding them to your project.
>
> This is my long term plan for shadow-utils, indeed. I'm first
> transforming strncpy(3) calls into strlcpy(3) to remove the superfluous
> padding, and later will use this strxcpy() to remove the truncated
> strings to avoid misinterpretation.
--
<https://www.alejandro-colomar.es/>
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next prev parent reply other threads:[~2023-11-09 12:43 UTC|newest]
Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-04 11:27 strncpy clarify result may not be null terminated Jonny Grant
2023-11-04 19:33 ` Alejandro Colomar
2023-11-04 21:18 ` Jonny Grant
2023-11-05 1:36 ` Alejandro Colomar
2023-11-05 21:16 ` Jonny Grant
2023-11-05 23:31 ` Alejandro Colomar
2023-11-07 11:52 ` Jonny Grant
2023-11-07 13:23 ` Alejandro Colomar
2023-11-07 14:19 ` Jonny Grant
2023-11-07 16:17 ` Alejandro Colomar
2023-11-07 17:00 ` Jonny Grant
2023-11-07 17:20 ` Alejandro Colomar
2023-11-08 6:18 ` Oskari Pirhonen
2023-11-08 9:51 ` Alejandro Colomar
2023-11-08 9:59 ` Thorsten Kukuk
2023-11-08 15:09 ` Alejandro Colomar
[not found] ` <6bcad2492ab843019aa63895beaea2ce@DB6PR04MB3255.eurprd04.prod.outlook.com>
2023-11-08 15:44 ` Thorsten Kukuk
2023-11-08 17:26 ` Adhemerval Zanella Netto
2023-11-08 14:06 ` Zack Weinberg
2023-11-08 15:07 ` Alejandro Colomar
2023-11-08 19:45 ` G. Branden Robinson
2023-11-08 21:35 ` Carlos O'Donell
2023-11-08 22:11 ` Alejandro Colomar
2023-11-08 23:31 ` Paul Eggert
2023-11-09 0:29 ` Alejandro Colomar
2023-11-09 10:13 ` Jonny Grant
2023-11-09 11:08 ` catenate vs concatenate (was: strncpy clarify result may not be null terminated) Alejandro Colomar
2023-11-09 14:06 ` catenate vs concatenate Jonny Grant
2023-11-27 14:33 ` catenate vs concatenate (was: strncpy clarify result may not be null terminated) Zack Weinberg
2023-11-27 15:08 ` Alejandro Colomar
2023-11-27 15:13 ` Alejandro Colomar
2023-11-27 16:59 ` G. Branden Robinson
2023-11-27 18:35 ` Zack Weinberg
2023-11-27 23:45 ` G. Branden Robinson
2023-11-09 11:13 ` strncpy clarify result may not be null terminated Alejandro Colomar
2023-11-09 14:05 ` Jonny Grant
2023-11-09 15:04 ` Alejandro Colomar
2023-11-08 19:04 ` DJ Delorie
2023-11-08 19:40 ` Alejandro Colomar
2023-11-08 19:58 ` DJ Delorie
2023-11-08 20:13 ` Alejandro Colomar
2023-11-08 21:07 ` DJ Delorie
2023-11-08 21:50 ` Alejandro Colomar
2023-11-08 22:17 ` [PATCH] stpncpy.3, string_copying.7: Clarify that st[rp]ncpy() do NOT produce a string Alejandro Colomar
2023-11-08 23:06 ` Paul Eggert
2023-11-08 23:28 ` DJ Delorie
2023-11-09 0:24 ` Alejandro Colomar
2023-11-09 14:11 ` Jonny Grant
2023-11-09 14:35 ` Alejandro Colomar
2023-11-09 14:47 ` Jonny Grant
2023-11-09 15:02 ` Alejandro Colomar
2023-11-09 17:30 ` DJ Delorie
2023-11-09 17:54 ` Andreas Schwab
2023-11-09 18:00 ` Alejandro Colomar
2023-11-09 19:42 ` Jonny Grant
2023-11-09 7:23 ` Oskari Pirhonen
2023-11-09 15:20 ` [PATCH v2 1/2] " Alejandro Colomar
2023-11-09 15:20 ` [PATCH v2 2/2] stpncpy.3, string.3, string_copying.7: Clarify that st[rp]ncpy() pad with null bytes Alejandro Colomar
2023-11-10 5:47 ` Oskari Pirhonen
2023-11-10 10:47 ` Alejandro Colomar
2023-11-08 2:12 ` strncpy clarify result may not be null terminated Matthew House
2023-11-08 19:33 ` Alejandro Colomar
2023-11-08 19:40 ` Alejandro Colomar
2023-11-09 3:13 ` Matthew House
2023-11-09 10:26 ` Jonny Grant
2023-11-09 10:31 ` Jonny Grant
2023-11-09 11:38 ` Alejandro Colomar
2023-11-09 12:43 ` Alejandro Colomar [this message]
2023-11-09 12:51 ` Xi Ruoyao
2023-11-09 14:01 ` Alejandro Colomar
2023-11-09 18:11 ` Paul Eggert
2023-11-09 23:48 ` Alejandro Colomar
2023-11-10 5:36 ` Paul Eggert
2023-11-10 11:05 ` Alejandro Colomar
2023-11-10 11:47 ` Alejandro Colomar
2023-11-10 17:58 ` Paul Eggert
2023-11-10 18:36 ` Alejandro Colomar
2023-11-10 20:19 ` Alejandro Colomar
2023-11-10 23:44 ` Jonny Grant
2023-11-10 19:52 ` Alejandro Colomar
2023-11-10 22:14 ` Paul Eggert
2023-11-11 21:13 ` Alejandro Colomar
2023-11-11 22:20 ` Paul Eggert
2023-11-12 9:52 ` Jonny Grant
2023-11-12 10:59 ` Alejandro Colomar
2023-11-12 20:49 ` Paul Eggert
2023-11-12 21:00 ` Alejandro Colomar
2023-11-12 21:45 ` Alejandro Colomar
2023-11-13 23:46 ` Jonny Grant
2023-11-17 21:57 ` Jonny Grant
2023-11-18 10:12 ` Alejandro Colomar
2023-11-18 23:03 ` Jonny Grant
2023-11-10 11:36 ` Jonny Grant
2023-11-10 13:15 ` Alejandro Colomar
2023-11-18 23:40 ` Jonny Grant
2023-11-20 11:56 ` Jonny Grant
2023-11-20 15:12 ` Alejandro Colomar
2023-11-20 23:08 ` Jonny Grant
2023-11-20 23:42 ` Alejandro Colomar
2023-11-10 11:23 ` Jonny Grant
2023-11-09 12:23 ` Alejandro Colomar
2023-11-09 12:35 ` Alejandro Colomar
2023-11-10 7:06 ` Oskari Pirhonen
2023-11-10 11:18 ` Alejandro Colomar
2023-11-11 7:55 ` Oskari Pirhonen
2023-11-10 16:06 ` Matthew House
2023-11-10 17:48 ` Alejandro Colomar
2023-11-13 15:01 ` Matthew House
2023-11-11 20:55 ` Jonny Grant
2023-11-11 21:15 ` Jonny Grant
2023-11-11 22:36 ` Alejandro Colomar
2023-11-11 23:19 ` Alejandro Colomar
2023-11-17 21:46 ` Jonny Grant
2023-11-18 9:37 ` PDF book of unreleased pages (was: strncpy clarify result may not be null terminated) Alejandro Colomar
2023-11-19 0:22 ` Deri
2023-11-19 1:19 ` Alejandro Colomar
2023-11-19 9:29 ` Alejandro Colomar
2023-11-19 16:21 ` Deri
2023-11-19 20:58 ` Alejandro Colomar
2023-11-20 0:46 ` G. Branden Robinson
2023-11-20 9:43 ` Alejandro Colomar
2023-11-18 9:44 ` NULL safety " Alejandro Colomar
2023-11-18 23:21 ` NULL safety Jonny Grant
2023-11-24 22:25 ` Alejandro Colomar
2023-11-25 0:57 ` Jonny Grant
2023-11-10 10:40 ` strncpy clarify result may not be null terminated Stefan Puiu
2023-11-10 11:06 ` Jonny Grant
2023-11-10 11:20 ` Alejandro Colomar
2023-11-12 9:17 ` [PATCH 0/2] Expand BUGS section of string_copying(7) Alejandro Colomar
2023-11-12 9:18 ` [PATCH 1/2] string_copying.7: BUGS: *cat(3) functions aren't always bad Alejandro Colomar
2023-11-12 9:18 ` [PATCH 2/2] string_copying.7: BUGS: Document strl{cpy,cat}(3)'s performance problems Alejandro Colomar
2023-11-12 11:26 ` [PATCH v2 0/3] Improve string_copying(7) Alejandro Colomar
2023-11-12 11:26 ` [PATCH v2 1/3] string_copying.7: BUGS: *cat(3) functions aren't always bad Alejandro Colomar
2023-11-17 21:43 ` Jonny Grant
2023-11-18 0:25 ` Signing all patches and email to this list Matthew House
2023-11-18 23:24 ` Jonny Grant
2023-11-12 11:26 ` [PATCH v2 2/3] string_copying.7: BUGS: Document strl{cpy,cat}(3)'s performance problems Alejandro Colomar
2023-11-12 11:27 ` [PATCH v2 3/3] strtcpy.3, string_copying.7: Add strtcpy(3) Alejandro Colomar
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