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Subject: Re: git: d549de769055 - main - libc: Remove readdir_r(3) [This broke
 building rust 1.88]
From: rb@gid.co.uk
In-Reply-To: <86qzwcgcmp.fsf@ltc.des.dev>
Date: Fri, 12 Sep 2025 20:09:33 +0100
Cc: Olivier Certner <olce@FreeBSD.org>,
        FreeBSD Current <freebsd-current@FreeBSD.org>,
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Hi,

> On 12 Sep 2025, at 11:59, Dag-Erling Sm=C3=B8rgrav <des@FreeBSD.org> =
wrote:
>=20
> Bob Bishop <rb@gid.co.uk> writes:
>> And while I=E2=80=99m here, POSIX.1 defines for readdir_r (and =
readdir):
>>=20
>> [EOVERFLOW]
>>   One of the values in the structure to be returned cannot be =
represented correctly.
>>=20
>> =E2=80=A6which I think would cover the case of indeterminate =
NAME_MAX/PATH_MAX for readdir_r.
>=20
> No, because readdir_r() has no way of knowing the size of the buffer
> that was passed to it.

It doesn=E2=80=99t need to know.

If NAME_MAX is defined, the user must supply an adequately sized buffer =
(based on NAME_MAX) or shoot themselves in the foot.

If NAME_MAX is indefinite, readdir_r() returns EOVERFLOW immediately.

> [=E2=80=A6]

--
Bob Bishop
rb@gid.co.uk