From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.gentoo.org (smtp.gentoo.org [IPv6:2001:470:ea4a:1:5054:ff:fec7:86e4]) by sourceware.org (Postfix) with ESMTP id 924783858D1E for ; Tue, 7 May 2024 11:38:44 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 924783858D1E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gentoo.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gentoo.org ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 924783858D1E Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=2001:470:ea4a:1:5054:ff:fec7:86e4 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1715081929; cv=none; b=Z1I0e0Hce7IinDpgjgSBTH4XV8wxLh3x6NplbwAmTE4fdr7ckdb9IG9Ks0dmeLgbUFfG+4wd4AlK8L56NvJUELOkqP5fFZ5yd87DC9sTunFPxjnZExkB92xlWdXwl1BjdMNT0Gtz9NgpbOyZuRNfiOPL8ObM3O7GugqGxwg+4WY= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1715081929; c=relaxed/simple; bh=hnGeE9StGVKvrBOPg9GALjmYpr6lLDrCbfIfDcvE9Ic=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=luyKAKBZb2ZvoAc+62CwA2JKv97G94He7tITSKqhWD+IS/BpXrMWF3qYekLpV8HNxCHRzy3s+UrdvFHoti7UKnXgeHe+nr/gk1ppLlgTRFbsSyJmANSKUB3A9YAwbsfJJ+dd5jonCuBgNM3Kuedw/7i1ngp0fUJsh6WngdNUt9s= ARC-Authentication-Results: i=1; server2.sourceware.org From: Sam James To: Florian Weimer Cc: libc-alpha@sourceware.org Subject: Re: [PATCH] socket: Use may_alias on sockaddr structs (bug 19622) In-Reply-To: <87v83q6kc2.fsf@oldenburg.str.redhat.com> (Florian Weimer's message of "Tue, 07 May 2024 11:29:49 +0200") Organization: Gentoo References: <87v83q6kc2.fsf@oldenburg.str.redhat.com> Date: Tue, 07 May 2024 12:38:32 +0100 Message-ID: <87v83pam2v.fsf@gentoo.org> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" X-Spam-Status: No, score=-10.5 required=5.0 tests=BAYES_00,GIT_PATCH_0,JMQ_SPF_NEUTRAL,KAM_DMARC_STATUS,RCVD_IN_DNSWL_LOW,SPF_HELO_PASS,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Florian Weimer writes: > This supports common coding paddings. GCC before version 8 > rejects the may_alias attribute on a struct definition if it was > not present in a previous forward declaration, so this attribute > can only be conditionally applied. > > Tested on i686-linux-gnu, x86_64-linux-gnu. Built with > build-many-glibcs.py. > > Suggested-by: Marek Polacek > Suggested-by: Jakub Jelinek Reviewed-by: Sam James > > --- > bits/socket.h | 4 ++-- > inet/netinet/in.h | 8 +++++--- > misc/sys/cdefs.h | 9 +++++++++ > socket/sys/un.h | 2 +- > sysdeps/mach/hurd/bits/socket.h | 4 ++-- > sysdeps/unix/sysv/linux/bits/socket.h | 4 ++-- > sysdeps/unix/sysv/linux/net/if_packet.h | 2 +- > sysdeps/unix/sysv/linux/netash/ash.h | 2 +- > sysdeps/unix/sysv/linux/neteconet/ec.h | 2 +- > sysdeps/unix/sysv/linux/netiucv/iucv.h | 2 +- > 10 files changed, 25 insertions(+), 14 deletions(-) > > diff --git a/bits/socket.h b/bits/socket.h > index 13de124bac..772074d52a 100644 > --- a/bits/socket.h > +++ b/bits/socket.h > @@ -149,7 +149,7 @@ enum __socket_type > #include >=20=20 > /* Structure describing a generic socket address. */ > -struct sockaddr > +struct __attribute_struct_may_alias__ sockaddr > { > __SOCKADDR_COMMON (sa_); /* Common data: address family and length. = */ > char sa_data[14]; /* Address data. */ > @@ -166,7 +166,7 @@ struct sockaddr > #define _SS_PADSIZE \ > (_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype)) >=20=20 > -struct sockaddr_storage > +struct __attribute_struct_may_alias__ sockaddr_storage > { > __SOCKADDR_COMMON (ss_); /* Address family, etc. */ > char __ss_padding[_SS_PADSIZE]; > diff --git a/inet/netinet/in.h b/inet/netinet/in.h > index fa57b61079..f684be5beb 100644 > --- a/inet/netinet/in.h > +++ b/inet/netinet/in.h > @@ -244,7 +244,7 @@ extern const struct in6_addr in6addr_loopback; /* := :1 */ >=20=20 >=20=20 > /* Structure describing an Internet socket address. */ > -struct sockaddr_in > +struct __attribute_struct_may_alias__ sockaddr_in > { > __SOCKADDR_COMMON (sin_); > in_port_t sin_port; /* Port number. */ > @@ -257,9 +257,11 @@ struct sockaddr_in > - sizeof (struct in_addr)]; > }; >=20=20 > -#if !__USE_KERNEL_IPV6_DEFS > +#if __USE_KERNEL_IPV6_DEFS > +struct __attribute_struct_may_alias__ sockaddr_in6; > +#else > /* Ditto, for IPv6. */ > -struct sockaddr_in6 > +struct __attribute_struct_may_alias__ sockaddr_in6 > { > __SOCKADDR_COMMON (sin6_); > in_port_t sin6_port; /* Transport layer port # */ > diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h > index 2e8279a2c7..e21a2a7080 100644 > --- a/misc/sys/cdefs.h > +++ b/misc/sys/cdefs.h > @@ -874,4 +874,13 @@ _Static_assert (0, "IEEE 128-bits long double requir= es redirection on this platf > # define __attribute_returns_twice__ /* Ignore. */ > #endif >=20=20 > +/* Mark struct types as aliasable. Restricted to compilers that > + support forward declarations of structs in the presence of the > + attribute. */ > +#if __GNUC_PREREQ (8, 0) || defined __clang__ > +# define __attribute_struct_may_alias__ __attribute__ ((__may_alias__)) > +#else > +# define __attribute_struct_may_alias__ > +#endif Consider doing '/* Ignore. */' for consistency, even if I think it's a bit silly. > + > #endif /* sys/cdefs.h */ > diff --git a/socket/sys/un.h b/socket/sys/un.h > index bf03b7d6ce..ff9cbd6efa 100644 > --- a/socket/sys/un.h > +++ b/socket/sys/un.h > @@ -26,7 +26,7 @@ > __BEGIN_DECLS >=20=20 > /* Structure describing the address of an AF_LOCAL (aka AF_UNIX) socket.= */ > -struct sockaddr_un > +struct __attribute_struct_may_alias__ sockaddr_un > { > __SOCKADDR_COMMON (sun_); > char sun_path[108]; /* Path name. */ > diff --git a/sysdeps/mach/hurd/bits/socket.h b/sysdeps/mach/hurd/bits/soc= ket.h > index 3e72f9fa93..b5eeac3731 100644 > --- a/sysdeps/mach/hurd/bits/socket.h > +++ b/sysdeps/mach/hurd/bits/socket.h > @@ -153,7 +153,7 @@ enum __socket_type > #include >=20=20 > /* Structure describing a generic socket address. */ > -struct sockaddr > +struct __attribute_struct_may_alias__ sockaddr > { > __SOCKADDR_COMMON (sa_); /* Common data: address family and length. = */ > char sa_data[14]; /* Address data. */ > @@ -170,7 +170,7 @@ struct sockaddr > #define _SS_PADSIZE \ > (_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype)) >=20=20 > -struct sockaddr_storage > +struct __attribute_struct_may_alias__ sockaddr_storage > { > __SOCKADDR_COMMON (ss_); /* Address family, etc. */ > char __ss_padding[_SS_PADSIZE]; > diff --git a/sysdeps/unix/sysv/linux/bits/socket.h b/sysdeps/unix/sysv/li= nux/bits/socket.h > index 86444f0018..5ab19a8c08 100644 > --- a/sysdeps/unix/sysv/linux/bits/socket.h > +++ b/sysdeps/unix/sysv/linux/bits/socket.h > @@ -181,7 +181,7 @@ typedef __socklen_t socklen_t; > #include >=20=20 > /* Structure describing a generic socket address. */ > -struct sockaddr > +struct __attribute_struct_may_alias__ sockaddr > { > __SOCKADDR_COMMON (sa_); /* Common data: address family and length. = */ > char sa_data[14]; /* Address data. */ > @@ -194,7 +194,7 @@ struct sockaddr > #define _SS_PADSIZE \ > (_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype)) >=20=20 > -struct sockaddr_storage > +struct __attribute_struct_may_alias__ sockaddr_storage > { > __SOCKADDR_COMMON (ss_); /* Address family, etc. */ > char __ss_padding[_SS_PADSIZE]; > diff --git a/sysdeps/unix/sysv/linux/net/if_packet.h b/sysdeps/unix/sysv/= linux/net/if_packet.h > index 9ffb69b508..c17e1c23c5 100644 > --- a/sysdeps/unix/sysv/linux/net/if_packet.h > +++ b/sysdeps/unix/sysv/linux/net/if_packet.h > @@ -26,7 +26,7 @@ > From Linux 2.1 the AF_PACKET interface is preferred and you should > consider using it in place of this one. */ >=20=20 > -struct sockaddr_pkt > +struct __attribute_struct_may_alias__ sockaddr_pkt > { > __SOCKADDR_COMMON (spkt_); > unsigned char spkt_device[14]; > diff --git a/sysdeps/unix/sysv/linux/netash/ash.h b/sysdeps/unix/sysv/lin= ux/netash/ash.h > index 7d885d17cc..7a6ff50b17 100644 > --- a/sysdeps/unix/sysv/linux/netash/ash.h > +++ b/sysdeps/unix/sysv/linux/netash/ash.h > @@ -22,7 +22,7 @@ > #include > #include >=20=20 > -struct sockaddr_ash > +struct __attribute_struct_may_alias__ sockaddr_ash > { > __SOCKADDR_COMMON (sash_); /* Common data: address family etc. */ > int sash_ifindex; /* Interface to use. */ > diff --git a/sysdeps/unix/sysv/linux/neteconet/ec.h b/sysdeps/unix/sysv/l= inux/neteconet/ec.h > index b07a107961..f3132f06ff 100644 > --- a/sysdeps/unix/sysv/linux/neteconet/ec.h > +++ b/sysdeps/unix/sysv/linux/neteconet/ec.h > @@ -28,7 +28,7 @@ struct ec_addr > unsigned char net; /* Network number. */ > }; >=20=20 > -struct sockaddr_ec > +struct __attribute_struct_may_alias__ sockaddr_ec > { > __SOCKADDR_COMMON (sec_); > unsigned char port; /* Port number. */ > diff --git a/sysdeps/unix/sysv/linux/netiucv/iucv.h b/sysdeps/unix/sysv/l= inux/netiucv/iucv.h > index f5fad81751..27151e8bbe 100644 > --- a/sysdeps/unix/sysv/linux/netiucv/iucv.h > +++ b/sysdeps/unix/sysv/linux/netiucv/iucv.h > @@ -23,7 +23,7 @@ >=20=20 > __BEGIN_DECLS >=20=20 > -struct sockaddr_iucv > +struct __attribute_struct_may_alias__ sockaddr_iucv > { > __SOCKADDR_COMMON (siucv_); > unsigned short siucv_port; /* Reserved */ > > base-commit: 4bbca1a44691a6e9adcee5c6798a707b626bc331 --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iOUEARYKAI0WIQQlpruI3Zt2TGtVQcJzhAn1IN+RkAUCZjoSul8UgAAAAAAuAChp c3N1ZXItZnByQG5vdGF0aW9ucy5vcGVucGdwLmZpZnRoaG9yc2VtYW4ubmV0MjVB NkJCODhERDlCNzY0QzZCNTU0MUMyNzM4NDA5RjUyMERGOTE5MA8cc2FtQGdlbnRv by5vcmcACgkQc4QJ9SDfkZC4wgEAz4olv8bzQ1uhIX9byNN/w/yUM0MZdO2vZTI2 9lZ44TUA/3n5vjrUBTfRek0PJ6Y8LOSuUVuTUp2yJs46F3paPvYD =xMJT -----END PGP SIGNATURE----- --=-=-=--