From: DJ Delorie <dj@redhat.com>
To: Alejandro Colomar <alx@kernel.org>
Cc: libc-alpha@sourceware.org, jg@jguk.org, linux-man@vger.kernel.org
Subject: Re: strncpy clarify result may not be null terminated
Date: Wed, 08 Nov 2023 14:04:45 -0500 [thread overview]
Message-ID: <xno7g4qd6a.fsf@greed.delorie.com> (raw)
In-Reply-To: <ZUtaH35V3koxTSL0@debian>
Alejandro Colomar <alx@kernel.org> writes:
> strncpy(3) is useful to write to fixed-width buffers like `struct utmp`
> and `struct utmpx`. Is there any other libc API that needs strncpy(3)?
Let's not limit ourselves to glibc APIs. Tar format, for example, uses
fixed length fields (and my bet is that strncpy was created for it) yet
tar is not part of glibc.
IMHO the solution here is to document strncpy with sufficiently obvious
intent that it is NOT a length-limited strcpy (i.e. strlcpy) and should
ONLY be used for its intended purpose (filling a space-padded but not
null-terminated field)
It is not documentation's purpose to limit programmer's creativity, just
to give them an accurate representation of what the functions do.
next prev parent reply other threads:[~2023-11-08 19:05 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 [this message]
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
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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