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[PATCH] bits/socket.h: Define struct sockaddr with may_alias attribute [BZ #19622]
- From: Florian Weimer <fweimer at redhat dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 12 Feb 2016 14:15:14 +0100
- Subject: [PATCH] bits/socket.h: Define struct sockaddr with may_alias attribute [BZ #19622]
- Authentication-results: sourceware.org; auth=none
It is quite common to use struct sockaddr * as an opaque, void *-like
type for socket addresses. The POSIX API encourages to some degree.
Marek Polacek suggested to add the may_alias attribute to the definition
of struct sockaddr.
Support for that was introduced in GCC 4.0, so I added a conditional to
cdefs.h.
Florian
2016-02-12 Florian Weimer <fweimer@redhat.com>
[BZ #19622]
* misc/sys/cdefs.h (__attribute_may_alias__): Define macro.
* bits/socket.h (struct sockaddr): Use it.
* sysdeps/mach/hurd/bits/socket.h (struct sockaddr): Likewise.
* sysdeps/unix/sysv/linux/bits/socket.h (struct sockaddr):
Likewise.
diff --git a/bits/socket.h b/bits/socket.h
index ab9f242..e090c65 100644
--- a/bits/socket.h
+++ b/bits/socket.h
@@ -148,7 +148,7 @@ struct sockaddr
{
__SOCKADDR_COMMON (sa_); /* Common data: address family and length. */
char sa_data[14]; /* Address data. */
- };
+ } __attribute_may_alias__;
/* Structure large enough to hold any socket address (with the historical
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 7fd4154..aee6ae3 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -407,6 +407,12 @@
[!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
#endif
+#if __GNUC_PREREQ (4,0)
+# define __attribute_may_alias__ __attribute__ ((__may_alias__))
+#else
+# define __attribute_may_alias__
+#endif
+
#include <bits/wordsize.h>
#if defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
diff --git a/sysdeps/mach/hurd/bits/socket.h b/sysdeps/mach/hurd/bits/socket.h
index 02c5dac..d0dc1a3 100644
--- a/sysdeps/mach/hurd/bits/socket.h
+++ b/sysdeps/mach/hurd/bits/socket.h
@@ -152,7 +152,7 @@ struct sockaddr
{
__SOCKADDR_COMMON (sa_); /* Common data: address family and length. */
char sa_data[14]; /* Address data. */
- };
+ } __attribute_may_alias__;
/* Structure large enough to hold any socket address (with the historical
diff --git a/sysdeps/unix/sysv/linux/bits/socket.h b/sysdeps/unix/sysv/linux/bits/socket.h
index 0581c79..420c0d3 100644
--- a/sysdeps/unix/sysv/linux/bits/socket.h
+++ b/sysdeps/unix/sysv/linux/bits/socket.h
@@ -154,7 +154,7 @@ struct sockaddr
{
__SOCKADDR_COMMON (sa_); /* Common data: address family and length. */
char sa_data[14]; /* Address data. */
- };
+ } __attribute_may_alias__;
/* Structure large enough to hold any socket address (with the historical