From: Andreas Schwab <schwab@suse.de>
To: Florian Weimer <fweimer@redhat.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [review] manual: Clarify strnlen, wcsnlen, strndup null termination behavior
Date: Wed, 30 Oct 2019 11:10:00 -0000 [thread overview]
Message-ID: <mvm4kzqh4kd.fsf@suse.de> (raw)
In-Reply-To: <875zk6337v.fsf@oldenburg2.str.redhat.com> (Florian Weimer's message of "Wed, 30 Oct 2019 12:03:16 +0100")
On Okt 30 2019, Florian Weimer wrote:
> * Andreas Schwab:
>
>> On Okt 30 2019, Florian Weimer wrote:
>>
>>> * Andreas Schwab:
>>>
>>>> On Okt 30 2019, Florian Weimer (Code Review) wrote:
>>>>
>>>>> +Note that @var{s} must be an array of at least @var{maxlen} bytes. It
>>>>> +is undefined to call @code{strnlen} on a shorter array, even if it is
>>>>> +known that the shorter array contains a null terminator.
>>>>
>>>> This is not true. strnlen _always_ stops before the null byte.
>>>
>>> This is not how it is specified in POSIX.
>>
>> Yes, it is.
>>
>> The strnlen() function shall return the number of bytes preceding
>> the first null byte in the array to which s points, if s contains a
>> null byte within the first maxlen bytes; otherwise, it shall return
>> maxlen.
>>
>> There is nothing undefined here. Your interpretation would be
>> completely useless anyway.
>
> It says âarrayâ
Yes, because a null terminator is not required.
> But it does NOT say that reading stops after the first null terminator.
Yes, it does, see above. Otherwise it doesn't make sense.
Andreas.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."
next prev parent reply other threads:[~2019-10-30 11:10 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-30 10:25 Florian Weimer (Code Review)
2019-10-30 10:44 ` Andreas Schwab
2019-10-30 10:55 ` Florian Weimer
2019-10-30 11:00 ` Andreas Schwab
2019-10-30 11:03 ` Florian Weimer
2019-10-30 11:10 ` Andreas Schwab [this message]
2019-10-30 12:01 ` Zack Weinberg
2019-10-30 16:20 ` Andreas Schwab
2019-10-30 16:31 ` Zack Weinberg
2019-10-30 16:47 ` Andreas Schwab
2019-10-30 16:58 ` Zack Weinberg
2019-10-30 17:26 ` Andreas Schwab
2019-10-30 18:12 ` Zack Weinberg
2019-10-30 18:36 ` Florian Weimer
2019-10-30 17:24 ` Joseph Myers
2019-11-28 9:43 ` Florian Weimer
2019-11-28 15:56 ` Carlos O'Donell
2019-11-28 15:58 ` Carlos O'Donell
2019-11-28 18:23 ` Rich Felker
2019-11-28 18:38 ` Szabolcs Nagy
2019-11-29 18:20 ` Martin Sebor
2019-11-27 19:08 ` Carlos O'Donell (Code Review)
2019-11-27 19:14 ` Florian Weimer (Code Review)
2019-11-27 22:11 ` Carlos O'Donell (Code Review)
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=mvm4kzqh4kd.fsf@suse.de \
--to=schwab@suse.de \
--cc=fweimer@redhat.com \
--cc=libc-alpha@sourceware.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;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).