From: Florian Weimer <fweimer@redhat.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: libc-alpha@sourceware.org, linux-man <linux-man@vger.kernel.org>,
Alejandro Colomar <alx@kernel.org>,
Linux API <linux-api@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, Karel Zak <kzak@redhat.com>,
Ian Kent <raven@themaw.net>,
David Howells <dhowells@redhat.com>,
Christian Brauner <christian@brauner.io>,
Amir Goldstein <amir73il@gmail.com>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: proposed libc interface and man page for statmount(2)
Date: Fri, 17 Nov 2023 15:47:08 +0100 [thread overview]
Message-ID: <87leawphcj.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <CAJfpegvqBtePer8HRuShe3PAHLbCg9YNUpOWzPg-+=gGwQJWpw@mail.gmail.com> (Miklos Szeredi's message of "Thu, 16 Nov 2023 22:01:27 +0100")
* Miklos Szeredi:
> On Thu, 16 Nov 2023 at 21:36, Florian Weimer <fweimer@redhat.com> wrote:
>
>> In addition to Adhemerval's observation that we'd prefer to have some
>> hint regarding the buffer size, it's probably better to have entirely
>> separate interfaces because it makes static analysis easier. With a
>> unified interface, we can still convey the information with an inline
>> wrapper function, but we can avoid that complexity.
>
> I'm not against having separate allocating and the non-allocating
> interfaces.
Thanks.
> But I don't think the allocating one needs a size hint. Your
> suggestion of passing a buffer on the stack to the syscall and then
> copying to an exact sized malloc should take care of it. If the
> stack buffer is sized generously, then the loop will never need to
> repeat for any real life case.
The strings could get fairly large if they ever contain key material,
especially for post-quantum cryptography.
We have plenty of experience with these double-buffer-and-retry
interfaces and glibc, and the failure mode once there is much more data
than initially expected can be quite bad. For new interfaces, I want a
way to avoid that. At least as long applications use statmount_allloc,
we have a way to switch to a different interface if that becomes
necessary just with a glibc-internal change.
Thanks,
Florian
next prev parent reply other threads:[~2023-11-17 14:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-15 15:08 proposed libc interface and man page for statmount(2) Miklos Szeredi
2023-11-16 20:12 ` Adhemerval Zanella Netto
2023-11-16 20:36 ` Florian Weimer
2023-11-16 21:01 ` Miklos Szeredi
2023-11-17 14:22 ` Miklos Szeredi
2023-11-17 14:47 ` Florian Weimer [this message]
2023-11-17 15:13 ` Miklos Szeredi
2023-11-17 15:50 ` Miklos Szeredi
2023-11-20 11:55 ` Miklos Szeredi
2023-11-20 12:16 ` Florian Weimer
2023-11-20 12:34 ` Miklos Szeredi
2023-11-20 23:56 ` Ian Kent
2023-11-21 0:58 ` Ian Kent
2023-11-21 1:12 ` Ian Kent
2023-11-21 1:33 ` Ian Kent
2023-11-21 19:42 ` Miklos Szeredi
2023-11-21 20:42 ` Zack Weinberg
2023-11-21 23:28 ` Ian Kent
2023-11-22 16:18 ` Zack Weinberg
2023-11-21 23:07 ` Ian Kent
2023-11-22 10:18 ` Christian Brauner
2023-11-20 15:38 ` Christian Brauner
2023-11-20 15:30 ` Christian Brauner
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