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 <polacek@redhat.com>
Suggested-by: Jakub Jelinek <jakub@redhat.com>
Reviewed-by: Sam James <sam@gentoo.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer 2024-05-18 09:33:19 +02:00
parent 2a99e2398d
commit 8d7b6b4cb2
10 changed files with 25 additions and 14 deletions

View File

@ -149,7 +149,7 @@ enum __socket_type
#include <bits/sockaddr.h> #include <bits/sockaddr.h>
/* Structure describing a generic socket address. */ /* Structure describing a generic socket address. */
struct sockaddr struct __attribute_struct_may_alias__ sockaddr
{ {
__SOCKADDR_COMMON (sa_); /* Common data: address family and length. */ __SOCKADDR_COMMON (sa_); /* Common data: address family and length. */
char sa_data[14]; /* Address data. */ char sa_data[14]; /* Address data. */
@ -166,7 +166,7 @@ struct sockaddr
#define _SS_PADSIZE \ #define _SS_PADSIZE \
(_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype)) (_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype))
struct sockaddr_storage struct __attribute_struct_may_alias__ sockaddr_storage
{ {
__SOCKADDR_COMMON (ss_); /* Address family, etc. */ __SOCKADDR_COMMON (ss_); /* Address family, etc. */
char __ss_padding[_SS_PADSIZE]; char __ss_padding[_SS_PADSIZE];

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@ -244,7 +244,7 @@ extern const struct in6_addr in6addr_loopback; /* ::1 */
/* Structure describing an Internet socket address. */ /* Structure describing an Internet socket address. */
struct sockaddr_in struct __attribute_struct_may_alias__ sockaddr_in
{ {
__SOCKADDR_COMMON (sin_); __SOCKADDR_COMMON (sin_);
in_port_t sin_port; /* Port number. */ in_port_t sin_port; /* Port number. */
@ -257,9 +257,11 @@ struct sockaddr_in
- sizeof (struct in_addr)]; - 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. */ /* Ditto, for IPv6. */
struct sockaddr_in6 struct __attribute_struct_may_alias__ sockaddr_in6
{ {
__SOCKADDR_COMMON (sin6_); __SOCKADDR_COMMON (sin6_);
in_port_t sin6_port; /* Transport layer port # */ in_port_t sin6_port; /* Transport layer port # */

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@ -874,4 +874,13 @@ _Static_assert (0, "IEEE 128-bits long double requires redirection on this platf
# define __attribute_returns_twice__ /* Ignore. */ # define __attribute_returns_twice__ /* Ignore. */
#endif #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 */ #endif /* sys/cdefs.h */

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@ -26,7 +26,7 @@
__BEGIN_DECLS __BEGIN_DECLS
/* Structure describing the address of an AF_LOCAL (aka AF_UNIX) socket. */ /* 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_); __SOCKADDR_COMMON (sun_);
char sun_path[108]; /* Path name. */ char sun_path[108]; /* Path name. */

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@ -153,7 +153,7 @@ enum __socket_type
#include <bits/sockaddr.h> #include <bits/sockaddr.h>
/* Structure describing a generic socket address. */ /* Structure describing a generic socket address. */
struct sockaddr struct __attribute_struct_may_alias__ sockaddr
{ {
__SOCKADDR_COMMON (sa_); /* Common data: address family and length. */ __SOCKADDR_COMMON (sa_); /* Common data: address family and length. */
char sa_data[14]; /* Address data. */ char sa_data[14]; /* Address data. */
@ -170,7 +170,7 @@ struct sockaddr
#define _SS_PADSIZE \ #define _SS_PADSIZE \
(_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype)) (_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype))
struct sockaddr_storage struct __attribute_struct_may_alias__ sockaddr_storage
{ {
__SOCKADDR_COMMON (ss_); /* Address family, etc. */ __SOCKADDR_COMMON (ss_); /* Address family, etc. */
char __ss_padding[_SS_PADSIZE]; char __ss_padding[_SS_PADSIZE];

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@ -181,7 +181,7 @@ typedef __socklen_t socklen_t;
#include <bits/sockaddr.h> #include <bits/sockaddr.h>
/* Structure describing a generic socket address. */ /* Structure describing a generic socket address. */
struct sockaddr struct __attribute_struct_may_alias__ sockaddr
{ {
__SOCKADDR_COMMON (sa_); /* Common data: address family and length. */ __SOCKADDR_COMMON (sa_); /* Common data: address family and length. */
char sa_data[14]; /* Address data. */ char sa_data[14]; /* Address data. */
@ -194,7 +194,7 @@ struct sockaddr
#define _SS_PADSIZE \ #define _SS_PADSIZE \
(_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype)) (_SS_SIZE - __SOCKADDR_COMMON_SIZE - sizeof (__ss_aligntype))
struct sockaddr_storage struct __attribute_struct_may_alias__ sockaddr_storage
{ {
__SOCKADDR_COMMON (ss_); /* Address family, etc. */ __SOCKADDR_COMMON (ss_); /* Address family, etc. */
char __ss_padding[_SS_PADSIZE]; char __ss_padding[_SS_PADSIZE];

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@ -26,7 +26,7 @@
From Linux 2.1 the AF_PACKET interface is preferred and you should From Linux 2.1 the AF_PACKET interface is preferred and you should
consider using it in place of this one. */ consider using it in place of this one. */
struct sockaddr_pkt struct __attribute_struct_may_alias__ sockaddr_pkt
{ {
__SOCKADDR_COMMON (spkt_); __SOCKADDR_COMMON (spkt_);
unsigned char spkt_device[14]; unsigned char spkt_device[14];

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@ -22,7 +22,7 @@
#include <features.h> #include <features.h>
#include <bits/sockaddr.h> #include <bits/sockaddr.h>
struct sockaddr_ash struct __attribute_struct_may_alias__ sockaddr_ash
{ {
__SOCKADDR_COMMON (sash_); /* Common data: address family etc. */ __SOCKADDR_COMMON (sash_); /* Common data: address family etc. */
int sash_ifindex; /* Interface to use. */ int sash_ifindex; /* Interface to use. */

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@ -28,7 +28,7 @@ struct ec_addr
unsigned char net; /* Network number. */ unsigned char net; /* Network number. */
}; };
struct sockaddr_ec struct __attribute_struct_may_alias__ sockaddr_ec
{ {
__SOCKADDR_COMMON (sec_); __SOCKADDR_COMMON (sec_);
unsigned char port; /* Port number. */ unsigned char port; /* Port number. */

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@ -23,7 +23,7 @@
__BEGIN_DECLS __BEGIN_DECLS
struct sockaddr_iucv struct __attribute_struct_may_alias__ sockaddr_iucv
{ {
__SOCKADDR_COMMON (siucv_); __SOCKADDR_COMMON (siucv_);
unsigned short siucv_port; /* Reserved */ unsigned short siucv_port; /* Reserved */