resolv: Move dn_skipname to its own file and into libc

And reformat it to GNU style.

dn_skipname is used outside glibc, so do not deprecate it,
and export it as dn_skipname (not __dn_skipname).  Due to internal
users, provide a __libc_dn_skipname alias, and keep __dn_skipname
as a pure compatibility symbol.

__dn_skipname@GLIBC_2.0 was moved using the script, and
dn_skipname@@GLIBC_2.34 was added using make update-all-abi.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

72 files changed, 178 insertions, 50 deletions

diff --git a/include/resolv.h b/include/resolv.h
index 602f184643..378b36d612 100644
--- a/include/resolv.h
+++ b/include/resolv.h
@@ -44,7 +44,6 @@ libresolv_hidden_proto (_sethtent)
 libresolv_hidden_proto (_gethtent)
 libresolv_hidden_proto (_gethtbyaddr)
 libresolv_hidden_proto (_gethtbyname2)
-libresolv_hidden_proto (__dn_skipname)
 libresolv_hidden_proto (__res_hnok)
 libresolv_hidden_proto (__res_dnok)
 libresolv_hidden_proto (__putlong)
@@ -66,6 +65,8 @@ libresolv_hidden_proto (__dn_count_labels)
 
 extern __typeof (dn_expand) __libc_dn_expand;
 libc_hidden_proto (__libc_dn_expand)
+extern __typeof (dn_skipname) __libc_dn_skipname;
+libc_hidden_proto (__libc_dn_skipname)
 
 # endif /* _RESOLV_H_ && !_ISOMAC */
 #endif
diff --git a/resolv/Makefile b/resolv/Makefile
index 936518523d..e1a608f4ac 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -30,6 +30,7 @@ headers	:= resolv.h bits/types/res_state.h \
 routines := \
   dn_comp \
   dn_expand \
+  dn_skipname \
   herror \
   inet_addr \
   inet_ntop \
diff --git a/resolv/Versions b/resolv/Versions
index e36cf45cfa..634c7833a8 100644
--- a/resolv/Versions
+++ b/resolv/Versions
@@ -1,6 +1,7 @@
 libc {
   GLIBC_2.0 {
     __dn_comp;
+    __dn_skipname;
     __h_errno_location;
     __res_randomid;
     _res;
@@ -45,6 +46,7 @@ libc {
 %endif
     dn_comp;
     dn_expand;
+    dn_skipname;
     ns_name_compress;
     ns_name_ntop;
     ns_name_pack;
@@ -61,6 +63,7 @@ libc {
     __inet_aton_exact;
     __inet_pton_length;
     __libc_dn_expand;
+    __libc_dn_skipname;
     __ns_name_compress;
     __ns_name_ntop;
     __ns_name_pack;
@@ -82,7 +85,6 @@ libresolv {
     __b64_ntop;
     __b64_pton;
     __dn_count_labels;
-    __dn_skipname;
     __fp_nquery;
     __fp_query;
     __fp_resstat;
diff --git a/resolv/dn_skipname.c b/resolv/dn_skipname.c
new file mode 100644
index 0000000000..b9a587faff
--- /dev/null
+++ b/resolv/dn_skipname.c
@@ -0,0 +1,103 @@
+/* Skipping over a compressed DNS domain name in wire format.
+   Copyright (C) 1995-2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+/*
+ * Copyright (c) 1985, 1993
+ *    The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVEN