Backport this upstream commit, but without the resolv/resolv.h change

which introduces the deprecation warning:

commit b76e065991ec01299225d9da90a627ebe6c1ac97

Author: Florian Weimer <fweimer@redhat.com>

Date:   Tue Oct 4 11:52:10 2016 +0200

    resolv: Deprecate the "inet6" option and RES_USE_INET6 [BZ #19582]

No Makefile changes are needed here because we have not backported the

resolver testsuite at this point.  Furthermore, due to the lack of

actual RES_USE_INET6 deprecation, resolv/gethnamaddr.c is not modified

in this patch (because it still compiles).

diff --git a/nis/nss_nis/nis-hosts.c b/nis/nss_nis/nis-hosts.c

index d79b0bd9c79173c8..fa2d79e7b69da57b 100644

--- a/nis/nss_nis/nis-hosts.c

+++ b/nis/nss_nis/nis-hosts.c

@@ -28,7 +28,7 @@

 #include <string.h>

 #include <netinet/in.h>

 #include <arpa/inet.h>

-#include <resolv.h>

+#include <resolv/resolv-internal.h>

 #include <bits/libc-lock.h>

 #include <rpcsvc/yp.h>

 #include <rpcsvc/ypclnt.h>

@@ -232,8 +232,8 @@ _nss_nis_gethostent_r (struct hostent *host, char *buffer, size_t buflen,

   __libc_lock_lock (lock);

   status = internal_nis_gethostent_r (host, buffer, buflen, errnop, h_errnop,

-			((_res.options & RES_USE_INET6) ? AF_INET6 : AF_INET),

-			((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0 ));

+			(res_use_inet6 () ? AF_INET6 : AF_INET),

+			(res_use_inet6 () ? AI_V4MAPPED : 0 ));

   __libc_lock_unlock (lock);

@@ -345,7 +345,7 @@ _nss_nis_gethostbyname2_r (const char *name, int af, struct hostent *host,

   return internal_gethostbyname2_r (name, af, host, buffer, buflen, errnop,

 				    h_errnop,

-			((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0));

+			(res_use_inet6 () ? AI_V4MAPPED : 0));

 }

@@ -353,7 +353,7 @@ enum nss_status

 _nss_nis_gethostbyname_r (const char *name, struct hostent *host, char *buffer,

 			  size_t buflen, int *errnop, int *h_errnop)

 {

-  if (_res.options & RES_USE_INET6)

+  if (res_use_inet6 ())

     {

       enum nss_status status;

@@ -427,9 +427,8 @@ _nss_nis_gethostbyaddr_r (const void *addr, socklen_t addrlen, int af,

   free (result);

   int parse_res = parse_line (p, host, data, buflen, errnop, af,

-			      ((_res.options & RES_USE_INET6)

-			       ? AI_V4MAPPED : 0));

-  if (__builtin_expect (parse_res < 1, 0))

+			      (res_use_inet6 () ? AI_V4MAPPED : 0));

+  if (__glibc_unlikely (parse_res < 1))

     {

       if (parse_res == -1)

 	{

diff --git a/nis/nss_nisplus/nisplus-hosts.c b/nis/nss_nisplus/nisplus-hosts.c

index 772d71097d6a2442..fb7461579b5408c9 100644

--- a/nis/nss_nisplus/nisplus-hosts.c

+++ b/nis/nss_nisplus/nisplus-hosts.c

@@ -43,6 +43,7 @@ static u_long tablename_len;

 	(NIS_RES_OBJECT (res)[idx].EN_data.en_cols.en_cols_val[col].ec_value.ec_value_len)

 /* Get implementation for some internal functions. */

+#include <resolv/resolv-internal.h>

 #include <resolv/mapv4v6addr.h>

@@ -321,7 +322,7 @@ internal_nisplus_gethostent_r (struct hostent *host, char *buffer,

 	    }

 	}

-      if (_res.options & RES_USE_INET6)

+      if (res_use_inet6 ())

 	parse_res = _nss_nisplus_parse_hostent (result, AF_INET6, host, buffer,

 						buflen, errnop, AI_V4MAPPED);

       else

@@ -488,7 +489,7 @@ _nss_nisplus_gethostbyname2_r (const char *name, int af, struct hostent *host,

   return internal_gethostbyname2_r (name, af, host, buffer, buflen, errnop,

 				    herrnop,

-			 ((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0));

+				    (res_use_inet6 () ? AI_V4MAPPED : 0));

 }

@@ -497,7 +498,7 @@ _nss_nisplus_gethostbyname_r (const char *name, struct hostent *host,

 			      char *buffer, size_t buflen, int *errnop,

 			      int *h_errnop)

 {

-  if (_res.options & RES_USE_INET6)

+  if (res_use_inet6 ())

     {

       enum nss_status status;

@@ -558,7 +559,7 @@ _nss_nisplus_gethostbyaddr_r (const void *addr, socklen_t addrlen, int af,

   parse_res = _nss_nisplus_parse_hostent (result, af, host,

 					  buffer, buflen, errnop,

-					  ((_res.options & RES_USE_INET6)

+					  (res_use_inet6 ()

 					   ? AI_V4MAPPED : 0));

   nis_freeresult (result);

diff --git a/nscd/aicache.c b/nscd/aicache.c

index abab042757920811..0ee25247cd464940 100644

--- a/nscd/aicache.c

+++ b/nscd/aicache.c

@@ -25,6 +25,7 @@

 #include <time.h>

 #include <unistd.h>

 #include <sys/mman.h>

+#include <resolv/resolv-internal.h>

 #include <resolv/res_hconf.h>

 #include "dbg_log.h"

@@ -112,7 +113,7 @@ addhstaiX (struct database_dyn *db, int fd, request_header *req,

      IPv6 addresses.  Currently this is decided by setting the

      RES_USE_INET6 bit in _res.options.  */

   int old_res_options = _res.options;

-  _res.options &= ~RES_USE_INET6;

+  _res.options &= ~DEPRECATED_RES_USE_INET6;

   size_t tmpbuf6len = 1024;

   char *tmpbuf6 = alloca (tmpbuf6len);

@@ -537,7 +538,7 @@ next_nip:

    }

  out:

-  _res.options |= old_res_options & RES_USE_INET6;

+  _res.options |= old_res_options & DEPRECATED_RES_USE_INET6;

   if (dataset != NULL && !alloca_used)

     {

diff --git a/nscd/nscd_gethst_r.c b/nscd/nscd_gethst_r.c

index d64ad2e7b6c9e58b..41488ed6c033ffcd 100644

--- a/nscd/nscd_gethst_r.c

+++ b/nscd/nscd_gethst_r.c

@@ -17,7 +17,7 @@

    <http://www.gnu.org/licenses/>.  */

 #include <errno.h>

-#include <resolv.h>

+#include <resolv/resolv-internal.h>

 #include <stdio.h>

 #include <string.h>

 #include <arpa/nameser.h>

@@ -41,7 +41,7 @@ __nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,

 {

   request_type reqtype;

-  reqtype = (_res.options & RES_USE_INET6) ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;

+  reqtype = res_use_inet6 () ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;

   return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,

 			buffer, buflen, result, h_errnop);

diff --git a/nss/digits_dots.c b/nss/digits_dots.c

index ee530c69610d5393..7a2b57bdebe03408 100644

--- a/nss/digits_dots.c

+++ b/nss/digits_dots.c

@@ -22,7 +22,7 @@

 #include <stdlib.h>

 #include <ctype.h>

 #include <wctype.h>

-#include <resolv.h>

+#include <resolv/resolv-internal.h>

 #include <netdb.h>

 #include <arpa/inet.h>

 #include "nsswitch.h"

@@ -80,7 +80,7 @@ __nss_hostname_digits_dots (const char *name, struct hostent *resbuf,

 	  break;

 	default:

-	  af = (_res.options & RES_USE_INET6) ? AF_INET6 : AF_INET;

+	  af = res_use_inet6 () ? AF_INET6 : AF_INET;

 	  addr_size = af == AF_INET6 ? IN6ADDRSZ : INADDRSZ;

 	  break;

 	}

@@ -167,7 +167,7 @@ __nss_hostname_digits_dots (const char *name, struct hostent *resbuf,

 		  (*h_addr_ptrs)[0] = (char *) host_addr;

 		  (*h_addr_ptrs)[1] = NULL;

 		  resbuf->h_addr_list = *h_addr_ptrs;

-		  if (af == AF_INET && (_res.options & RES_USE_INET6))

+		  if (af == AF_INET && res_use_inet6 ())

 		    {

 		      /* We need to change the IP v4 address into the

 			 IP v6 address.  */

@@ -211,7 +211,7 @@ __nss_hostname_digits_dots (const char *name, struct hostent *resbuf,

 	  switch (af)

 	    {

 	    default:

-	      af = (_res.options & RES_USE_INET6) ? AF_INET6 : AF_INET;

+	      af = res_use_inet6 () ? AF_INET6 : AF_INET;

 	      if (af == AF_INET6)

 		{

 		  addr_size = IN6ADDRSZ;

diff --git a/nss/nss_files/files-hosts.c b/nss/nss_files/files-hosts.c

index 6c06b89dc179fd9a..b25ebe5ed19bdded 100644

--- a/nss/nss_files/files-hosts.c

+++ b/nss/nss_files/files-hosts.c

@@ -21,7 +21,7 @@

 #include <arpa/inet.h>

 #include <arpa/nameser.h>

 #include <netdb.h>

-#include <resolv.h>

+#include <resolv/resolv-internal.h>

 /* Get implementation for some internal functions.  */

@@ -98,8 +98,8 @@ LINE_PARSER

  })

 #define EXTRA_ARGS_VALUE \

-  , ((_res.options & RES_USE_INET6) ? AF_INET6 : AF_INET),		      \

-  ((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0)

+  , (res_use_inet6 () ? AF_INET6 : AF_INET),		      \

+  (res_use_inet6 () ? AI_V4MAPPED : 0)

 #include "files-XXX.c"

 #undef EXTRA_ARGS_VALUE

@@ -133,7 +133,7 @@ _nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,

     {

       /* XXX Is using _res to determine whether we want to convert IPv4

          addresses to IPv6 addresses really the right thing to do?  */

-      int flags = ((_res.options & RES_USE_INET6) ? AI_V4MAPPED : 0);

+      int flags = (res_use_inet6 () ? AI_V4MAPPED : 0);

       /* Tell getent function that we have repositioned the file pointer.  */

       last_use = getby;

@@ -358,7 +358,7 @@ _nss_files_gethostbyname_r (const char *name, struct hostent *result,

 			    char *buffer, size_t buflen, int *errnop,

 			    int *herrnop)

 {

-  int af = ((_res.options & RES_USE_INET6) ? AF_INET6 : AF_INET);

+  int af = (res_use_inet6 () ? AF_INET6 : AF_INET);

   return _nss_files_gethostbyname3_r (name, af, result, buffer, buflen,

 				      errnop, herrnop, NULL, NULL);

diff --git a/resolv/README b/resolv/README

index 416205da77a15564..1a70bbb1dc615ac9 100644

--- a/resolv/README

+++ b/resolv/README

@@ -84,11 +84,7 @@ code:

 * In Multi-threaded that manipulate the _res structure, calls to

   functions like `gethostbyname' in threads other than the "main"

-  thread won't be influenced by the those changes anymore.  So if you

-  set RES_USE_INET6, a call to `gethostbyname' won't return any IPv6

-  hosts anymore.  If you recompile such programs, manipulating the

-  _res structure will affect the thread in which you do so instead of

-  the "main" thread.

+  thread won't be influenced by the those changes anymore.

 We recommend to use the new thread-safe interfaces in new code, since

 the traditional interfaces have been deprecated by the BIND folks.

diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c

index 774d575dd1ce22af..7fc154db5d3130a3 100644

--- a/resolv/nss_dns/dns-host.c

+++ b/resolv/nss_dns/dns-host.c

@@ -82,7 +82,8 @@

 #include "nsswitch.h"

-/* Get implementation for some internal functions.  */

+/* Get implementeation for some internal functions.  */

+#include <resolv/resolv-internal.h>

 #include <resolv/mapv4v6addr.h>

 #include <resolv/mapv4v6hostent.h>

@@ -221,7 +222,7 @@ _nss_dns_gethostbyname3_r (const char *name, int af, struct hostent *result,

       /* If we are looking for an IPv6 address and mapping is enabled

 	 by having the RES_USE_INET6 bit in _res.options set, we try

 	 another lookup.  */

-      if (af == AF_INET6 && (_res.options & RES_USE_INET6))

+      if (af == AF_INET6 && res_use_inet6 ())

 	n = __libc_res_nsearch (&_res, name, C_IN, T_A, host_buffer.buf->buf,

 				host_buffer.buf != orig_host_buffer

 				? MAXPACKET : 1024, &host_buffer.ptr,

@@ -266,7 +267,7 @@ _nss_dns_gethostbyname_r (const char *name, struct hostent *result,

 {

   enum nss_status status = NSS_STATUS_NOTFOUND;

-  if (_res.options & RES_USE_INET6)

+  if (res_use_inet6 ())

     status = _nss_dns_gethostbyname3_r (name, AF_INET6, result, buffer,

 					buflen, errnop, h_errnop, NULL, NULL);

   if (status == NSS_STATUS_NOTFOUND)

@@ -519,17 +520,6 @@ _nss_dns_gethostbyaddr2_r (const void *addr, socklen_t len, int af,

   memcpy (host_data->host_addr, addr, len);

   host_data->h_addr_ptrs[0] = (char *) host_data->host_addr;

   host_data->h_addr_ptrs[1] = NULL;

-#if 0

-  /* XXX I think this is wrong.  Why should an IPv4 address be

-     converted to IPv6 if the user explicitly asked for IPv4?  */

-  if (af == AF_INET && (_res.options & RES_USE_INET6))

-    {

-      map_v4v6_address ((char *) host_data->host_addr,

-			(char *) host_data->host_addr);

-      result->h_addrtype = AF_INET6;

-      result->h_length = IN6ADDRSZ;

-    }

-#endif

   *h_errnop = NETDB_SUCCESS;

   return NSS_STATUS_SUCCESS;

 }

diff --git a/resolv/res_debug.c b/resolv/res_debug.c

index 3daa44e273db5a41..6549e4ba5ee77f93 100644

--- a/resolv/res_debug.c

+++ b/resolv/res_debug.c

@@ -106,7 +106,7 @@ static const char rcsid[] = "$BINDId: res_debug.c,v 8.34 2000/02/29 05:30:55 vix

 #include <errno.h>

 #include <math.h>

 #include <netdb.h>

-#include <resolv.h>

+#include <resolv/resolv-internal.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

@@ -582,7 +582,7 @@ p_option(u_long option) {

 	case RES_DNSRCH:	return "dnsrch";

 	case RES_INSECURE1:	return "insecure1";

 	case RES_INSECURE2:	return "insecure2";

-	case RES_USE_INET6:	return "inet6";

+	case DEPRECATED_RES_USE_INET6:	return "inet6";

 	case RES_ROTATE:	return "rotate";

 	case RES_NOCHECKNAME:	return "no-check-names";

 	case RES_USEBSTRING:	return "ip6-bytstring";

diff --git a/resolv/res_init.c b/resolv/res_init.c

index 2e3d0f746e855aff..0ed74e0520131418 100644

--- a/resolv/res_init.c

+++ b/resolv/res_init.c

@@ -71,7 +71,7 @@ static const char rcsid[] = "$BINDId: res_init.c,v 8.16 2000/05/09 07:10:12 vixi

 #include <ctype.h>

 #include <netdb.h>

-#include <resolv.h>

+#include <resolv/resolv-internal.h>

 #include <stdio.h>

 #include <stdio_ext.h>

 #include <stdlib.h>

@@ -530,7 +530,7 @@ res_setoptions(res_state statp, const char *options, const char *source) {

 		    unsigned long int flag;

 		  } options[] = {

 #define STRnLEN(str) str, sizeof (str) - 1

-		    { STRnLEN ("inet6"), 0, RES_USE_INET6 },

+		    { STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },

 		    { STRnLEN ("ip6-bytestring"), 0, RES_USEBSTRING },

 		    { STRnLEN ("no-ip6-dotint"), 0, RES_NOIP6DOTINT },

 		    { STRnLEN ("ip6-dotint"), 1, ~RES_NOIP6DOTINT },

diff --git a/resolv/resolv-internal.h b/resolv/resolv-internal.h

new file mode 100644

index 0000000000000000..269758c416544cb4

--- /dev/null

+++ b/resolv/resolv-internal.h

@@ -0,0 +1,35 @@

+/* libresolv interfaces for internal use across glibc.

+   Copyright (C) 2016 Free Software Foundation, Inc.

+   This file is part of the GNU C Library.

+

+   The GNU C Library is free software; you can redistribute it and/or

+   modify it under the terms of the GNU Lesser General Public

+   License as published by the Free Software Foundation; either

+   version 2.1 of the License, or (at your option) any later version.

+

+   The GNU C Library is distributed in the hope that it will be useful,

+   but WITHOUT ANY WARRANTY; without even the implied warranty of

+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

+   Lesser General Public License for more details.

+

+   You should have received a copy of the GNU Lesser General Public

+   License along with the GNU C Library; if not, see

+   <http://www.gnu.org/licenses/>.  */

+

+#ifndef _RESOLV_INTERNAL_H

+#define _RESOLV_INTERNAL_H 1

+

+#include <resolv.h>

+#include <stdbool.h>

+

+/* Internal version of RES_USE_INET6 which does not trigger a

+   deprecation warning.  */

+#define DEPRECATED_RES_USE_INET6 0x00002000

+

+static inline bool

+res_use_inet6 (void)

+{

+  return _res.options & DEPRECATED_RES_USE_INET6;

+}

+

+#endif  /* _RESOLV_INTERNAL_H */

diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c

index a678d8d7e8b23d1d..7a6cf71c170ec42f 100644

--- a/sysdeps/posix/getaddrinfo.c

+++ b/sysdeps/posix/getaddrinfo.c

@@ -41,7 +41,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #include <ifaddrs.h>

 #include <netdb.h>

 #include <nss.h>

-#include <resolv.h>

+#include <resolv/resolv-internal.h>

 #include <stdbool.h>

 #include <stdio.h>

 #include <stdio_ext.h>

@@ -222,7 +222,7 @@ gaih_inet_serv (const char *servicename, const struct gaih_typeproto *tp,

       if (herrno == NETDB_INTERNAL)					      \

 	{								      \

 	  __set_h_errno (herrno);					      \

-	  _res.options |= old_res_options & RES_USE_INET6;		      \

+	  _res.options |= old_res_options & DEPRECATED_RES_USE_INET6;	      \

 	  result = -EAI_SYSTEM;						      \

 	  goto free_and_return;						      \

 	}								      \

@@ -839,7 +839,7 @@ gaih_inet (const char *name, const struct gaih_service *service,

 	     addresses to IPv6 addresses.  Currently this is decided

 	     by setting the RES_USE_INET6 bit in _res.options.  */

 	  old_res_options = _res.options;

-	  _res.options &= ~RES_USE_INET6;

+	  _res.options &= ~DEPRECATED_RES_USE_INET6;

 	  size_t tmpbuflen = 1024 + sizeof(struct gaih_addrtuple);

 	  malloc_tmpbuf = !__libc_use_alloca (alloca_used + tmpbuflen);

@@ -900,7 +900,7 @@ gaih_inet (const char *name, const struct gaih_service *service,

 						2 * tmpbuflen);

 			  if (newp == NULL)

 			    {

-			      _res.options |= old_res_options & RES_USE_INET6;

+			      _res.options |= old_res_options & DEPRECATED_RES_USE_INET6;

 			      result = -EAI_MEMORY;

 			      goto free_and_return;

 			    }

@@ -1021,7 +1021,8 @@ gaih_inet (const char *name, const struct gaih_service *service,

 				      if (canonbuf == NULL)

 					{

 					  _res.options

-					    |= old_res_options & RES_USE_INET6;

+					    |= old_res_options

+					       & DEPRECATED_RES_USE_INET6;

 					  result = -EAI_MEMORY;

 					  goto free_and_return;

 					}

@@ -1082,7 +1083,7 @@ gaih_inet (const char *name, const struct gaih_service *service,

 		nip = nip->next;

 	    }

-	  _res.options |= old_res_options & RES_USE_INET6;

+	  _res.options |= old_res_options & DEPRECATED_RES_USE_INET6;

 	  if (h_errno == NETDB_INTERNAL)

 	    {