From 26e7005728f0eea2972474e6be2905c467661237 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Sat, 18 May 2024 09:33:19 +0200 Subject: socket: Use may_alias on sockaddr structs (bug 19622) This supports common coding patterns. The GCC C front end before version 7 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. This implements the spirit of the change in Austin Group issue 1641. Suggested-by: Marek Polacek Suggested-by: Jakub Jelinek Reviewed-by: Sam James Reviewed-by: Carlos O'Donell (cherry picked from commit 8d7b6b4cb27d4dec1dd5f7960298c1699275f962) --- 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 /* 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)) -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 */ /* 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)]; }; -#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 520231dbea..399ee7d24c 100644 --- a/misc/sys/cdefs.h +++ b/misc/sys/cdefs.h @@ -720,4 +720,13 @@ _Static_assert (0, "IEEE 128-bits long double requires redirection on this platf # define __attribute_returns_twice__ /* Ignore. */ #endif +/* Mark struct types as aliasable. Restricted to compilers that + support forward declarations of structs in the presence of the + attribute. */ +#if __GNUC_PREREQ (7, 1) || defined __clang__ +# define __attribute_struct_may_alias__ __attribute__ ((__may_alias__)) +#else +# define __attribute_struct_may_alias__ +#endif + #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 /* 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/socket.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 /* 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)) -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/linux/bits/socket.h index 0d86feb4ca..6dab283a2e 100644 --- a/sysdeps/unix/sysv/linux/bits/socket.h +++ b/sysdeps/unix/sysv/linux/bits/socket.h @@ -180,7 +180,7 @@ typedef __socklen_t socklen_t; #include /* 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. */ @@ -193,7 +193,7 @@ struct sockaddr #define _SS_PADSIZE \ (_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype)) -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. */ -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/linux/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 -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/linux/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. */ }; -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/linux/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 @@ __BEGIN_DECLS -struct sockaddr_iucv +struct __attribute_struct_may_alias__ sockaddr_iucv { __SOCKADDR_COMMON (siucv_); unsigned short siucv_port; /* Reserved */ -- cgit 1.4.1