Fix gethostbyaddr in6addr_any, in6addr_loopback namespace (bug 18532).

gethostbyaddr brings in references to in6addr_any and thereby
in6addr_loopback, which aren't in all the standards containing
gethostbyaddr (gethostbyaddr is in XPG4 and UNIX98, in6addr_any and
in6addr_loopback are new in POSIX.1:2001).  This patch fixes this by
making those symbols into weak aliases (safe in this case, unlike for
most data symbols, because these data symbols are const).

Tested for x86_64 and x86 (testsuite, and comparison of disassembly of
installed stripped shared libraries).  Disassembly is unchanged for
x86_64; for x86, I see some changes of stack offsets, but no other
code generation changes or code size differences.

	[BZ #18532]
	* inet/in6_addr.c (in6addr_any): Rename to __in6addr_any and
	define as weak alias of __in6addr_any.  Use libc_hidden_data_weak.
	(in6addr_loopback): Rename to __in6addr_loopback and define as
	weak alias of __in6addr_loopback.  Use libc_hidden_data_weak.
	* include/netinet/in.h (__in6addr_loopback): Declare.  Use
	libc_hidden_proto.
	(__in6addr_any): Likewise.
	* inet/gethstbyad_r.c (PREPROCESS): Use __in6addr_any instead of
	in6addr_any.
	* conform/Makefile (test-xfail-XPG4/netdb.h/linknamespace): Remove
	variable.
	(test-xfail-UNIX98/netdb.h/linknamespace): Likewise.

ChangeLog

@@ -1,3 +1,19 @@
+2015-06-17  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #18532]
+	* inet/in6_addr.c (in6addr_any): Rename to __in6addr_any and
+	define as weak alias of __in6addr_any.  Use libc_hidden_data_weak.
+	(in6addr_loopback): Rename to __in6addr_loopback and define as
+	weak alias of __in6addr_loopback.  Use libc_hidden_data_weak.
+	* include/netinet/in.h (__in6addr_loopback): Declare.  Use
+	libc_hidden_proto.
+	(__in6addr_any): Likewise.
+	* inet/gethstbyad_r.c (PREPROCESS): Use __in6addr_any instead of
+	in6addr_any.
+	* conform/Makefile (test-xfail-XPG4/netdb.h/linknamespace): Remove
+	variable.
+	(test-xfail-UNIX98/netdb.h/linknamespace): Likewise.
+
 2015-06-17  Andrew Senkevich  <andrew.senkevich@intel.com>
 
 	* bits/libm-simd-decl-stubs.h: Added stubs for pow.

NEWS

@@ -21,7 +21,7 @@ Version 2.22
   18210, 18211, 18217, 18220, 18221, 18234, 18244, 18247, 18287, 18319,
   18324, 18333, 18346, 18397, 18409, 18410, 18412, 18418, 18422, 18434,
   18444, 18468, 18469, 18470, 18479, 18483, 18495, 18496, 18497, 18498,
-  18507, 18512, 18519, 18520, 18522, 18527, 18528, 18529, 18530.
+  18507, 18512, 18519, 18520, 18522, 18527, 18528, 18529, 18530, 18532.
 
 * Cache information can be queried via sysconf() function on s390 e.g. with
   _SC_LEVEL1_ICACHE_SIZE as argument.

conform/Makefile

@@ -346,14 +346,12 @@ test-xfail-XOPEN2K8/ndbm.h/linknamespace = yes
 # Unsorted expected failures.
 test-xfail-XPG3/unistd.h/linknamespace = yes
 test-xfail-XPG4/fmtmsg.h/linknamespace = yes
-test-xfail-XPG4/netdb.h/linknamespace = yes
 test-xfail-XPG4/syslog.h/linknamespace = yes
 test-xfail-XPG4/unistd.h/linknamespace = yes
 test-xfail-POSIX/mqueue.h/linknamespace = yes
 test-xfail-POSIX/semaphore.h/linknamespace = yes
 test-xfail-UNIX98/fmtmsg.h/linknamespace = yes
 test-xfail-UNIX98/mqueue.h/linknamespace = yes
-test-xfail-UNIX98/netdb.h/linknamespace = yes
 test-xfail-UNIX98/syslog.h/linknamespace = yes
 test-xfail-UNIX98/unistd.h/linknamespace = yes
 test-xfail-UNIX98/wchar.h/linknamespace = yes

include/netinet/in.h

@@ -5,7 +5,11 @@
 #ifndef _ISOMAC
 libc_hidden_proto (bindresvport)
 libc_hidden_proto (in6addr_loopback)
+extern __typeof (in6addr_loopback) __in6addr_loopback;
+libc_hidden_proto (__in6addr_loopback)
 libc_hidden_proto (in6addr_any)
+extern __typeof (in6addr_any) __in6addr_any;
+libc_hidden_proto (__in6addr_any)
 #endif
 
 #endif

inet/gethstbyad_r.c

@@ -32,7 +32,7 @@
    be performed.  */
 #define PREPROCESS \
   if (len == sizeof (struct in6_addr)					      \
-      && __builtin_expect (memcmp (&in6addr_any, addr,			      \
+      && __builtin_expect (memcmp (&__in6addr_any, addr,		      \
 				   sizeof (struct in6_addr)), 1) == 0)	      \
     {									      \
       *h_errnop = HOST_NOT_FOUND;					      \

inet/in6_addr.c

@@ -18,9 +18,13 @@
 
 #include <netinet/in.h>
 
-const struct in6_addr in6addr_any =
+const struct in6_addr __in6addr_any =
 { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 } } };
-libc_hidden_data_def (in6addr_any)
-const struct in6_addr in6addr_loopback =
+libc_hidden_data_def (__in6addr_any)
+weak_alias (__in6addr_any, in6addr_any)
+libc_hidden_data_weak (in6addr_any)
+const struct in6_addr __in6addr_loopback =
 { { { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1 } } };
-libc_hidden_data_def (in6addr_loopback)
+libc_hidden_data_def (__in6addr_loopback)
+weak_alias (__in6addr_loopback, in6addr_loopback)
+libc_hidden_data_weak (in6addr_loopback)