From: Gabriel Ravier <gabravier@gmail.com>
To: musl@lists.openwall.com, Joakim Sindholt <opensource@zhasha.com>
Subject: Re: [musl] ecvt(0, 0, ...) is broken
Date: Tue, 6 Sep 2022 14:21:52 +0200 [thread overview]
Message-ID: <166c0b26-198a-91d3-08c9-ba135fc57065@gmail.com> (raw)
In-Reply-To: <20220906141311.b8650027f3499c080f45b4fd@zhasha.com>
On 9/6/22 14:13, Joakim Sindholt wrote:
> On Tue, 6 Sep 2022 12:12:48 +0200, Gabriel Ravier <gabravier@gmail.com> wrote:
>> Executing ecvt(0, 0, &decpt, &sign) results in musl returning
>> "000000000000000".
>>
>> This seems highly likely to be a bug considering that glibc returns ""
>> and I see no plausible reasoning for musl's behavior that could be
>> justified by the standard.
> POSIX.1-2001 said:
>> The ecvt() function shall convert value to a null-terminated string of
>> ndigit digits (where ndigit is reduced to an unspecified limit
>> determined by the precision of a double) and return a pointer to the
>> string. The high-order digit shall be non-zero, unless the value is 0.
> The first part would imply that ndigit=0 should return the string "" but
> the second part makes no provision for a zero-digit-long string.
> I would say ndigit=0 is UB.
Wouldn't that then mean that any request call of fcvt with a small
ndigits but very small value that isn't 0, as in my previous email,
would also be UB (since if my logic is correct, the string cannot start
with a 0 but it also cannot start with any other value, which forces it
to be empty) ? That seems rather excessive...
next prev parent reply other threads:[~2022-09-06 12:22 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-06 9:27 [musl] Bug report: fcvt seems dysfunctional Gabriel Ravier
2022-09-06 10:12 ` [musl] ecvt(0, 0, ...) is broken Gabriel Ravier
2022-09-06 12:13 ` Joakim Sindholt
2022-09-06 12:21 ` Gabriel Ravier [this message]
2022-09-06 14:17 ` Rich Felker
2022-09-06 18:48 ` Markus Wichmann
2022-09-06 19:19 ` Rich Felker
2022-09-07 3:39 ` Markus Wichmann
2022-09-07 3:51 ` Jeffrey Walton
2022-09-07 13:44 ` Rich Felker
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=166c0b26-198a-91d3-08c9-ba135fc57065@gmail.com \
--to=gabravier@gmail.com \
--cc=musl@lists.openwall.com \
--cc=opensource@zhasha.com \
/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.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
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 NNTP newsgroup(s).