From: "Bastien Roucariès" <rouca@debian.org>
To: Alejandro Colomar <alx.manpages@gmail.com>
Cc: "linux-man@vger.kernel.org" <linux-man@vger.kernel.org>,
eblake <eblake@redhat.com>, Zack Weinberg <zack@owlfolio.org>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: struct sockaddr_storage, union (was: Improve getsockname)
Date: Fri, 20 Jan 2023 21:11:28 +0000 [thread overview]
Message-ID: <1698201.vqxVuVRdHc@portable-bastien> (raw)
In-Reply-To: <528e35f3-ee79-52e0-be5b-ea5572cf3d07@gmail.com>
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Le jeudi 19 janvier 2023, 23:31:09 UTC Alejandro Colomar a écrit :
Hi,
> On 1/19/23 22:38, Bastien Roucariès wrote:
>
> However... Considering that most APIs use `struct sockaddr *`, this wouldn't
> allow the internal libc implementation of functions like getnameinfo(3) to be
> free of UB.
libc is safe thanks to the transparent union of pointer.
> Maybe a better thing would be to do the following:
>
>
> struct sockaddr {
> union {
> struct {
> sa_family_t sa_family;
> char sa_data[];
> };
> struct sockaddr_in sin;
> struct sockaddr_in6 sin6;
> struct sockaddr_un sun;
> };
> };
>
> struct sockaddr_storage {
> union {
> sa_family_t ss_family;
> struct sockaddr sa;
> };
> };
>
No I think we could do better with recent C:
struct osockaddr
{
unsigned short int sa_family;
unsigned char sa_data[14];
char _extra[];
};
> This makes sockaddr and sockaddr_storage have the same size, and also both can
> alias any of the children types through the unions, so one can use either of
> them for the same purpose.
We could not due to old talk protocol
Only storage is free
>
> I'll be sending a patch soon for discussion.
>
> Cheers,
>
> Alex
>
> >
> >>
> >>>
> >>> struct sockaddr_storage {
> >>> union {
> >>> sa_family_t ss_family;
> >>> struct sockaddr sa;
> >>> struct sockaddr_in sin;
> >>> struct sockaddr_in6 sin6;
> >>> struct sockaddr_un sun;
> >>> };
> >>> char __reserved_null;
> >>
>
> --
> <http://www.alejandro-colomar.es/>
>
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prev parent reply other threads:[~2023-01-20 21:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 10:22 Improve getsockname Bastien Roucariès
2023-01-19 12:42 ` Alejandro Colomar
2023-01-19 19:44 ` Bastien Roucariès
2023-01-19 20:19 ` struct sockaddr_storage, union (was: Improve getsockname) Alejandro Colomar
2023-01-19 21:00 ` Bastien Roucariès
2023-01-19 21:19 ` Alejandro Colomar
2023-01-19 21:38 ` Bastien Roucariès
2023-01-19 23:31 ` Alejandro Colomar
2023-01-20 0:12 ` Alejandro Colomar
2023-01-20 21:11 ` Bastien Roucariès [this message]
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