resolv: Move dn_comp to its own file and into libc

And reformat it to GNU style.

dn_comp is used in various programs, so keep it as a non-deprecated
symbol.  Switch to dn_comp (not __dn_comp) for the ABI name.  There
are no internal users, so interposition is not a problem.

The __dn_comp symbol was moved with scripts/move-symbol-to-libc.py
--no-new-version.  dn_comp@@GLIBC_2.34 was added with
make update-all-abi.

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

70 files changed, 172 insertions, 49 deletions

diff --git a/include/resolv.h b/include/resolv.h
index 44fc0c346f..602f184643 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_comp)
 libresolv_hidden_proto (__dn_skipname)
 libresolv_hidden_proto (__res_hnok)
 libresolv_hidden_proto (__res_dnok)
diff --git a/resolv/Makefile b/resolv/Makefile
index 07cac54d3a..936518523d 100644
--- a/resolv/Makefile
+++ b/resolv/Makefile
@@ -28,6 +28,7 @@ headers	:= resolv.h bits/types/res_state.h \
 	   sys/bitypes.h
 
 routines := \
+  dn_comp \
   dn_expand \
   herror \
   inet_addr \
diff --git a/resolv/Versions b/resolv/Versions
index 4a9203042f..e36cf45cfa 100644
--- a/resolv/Versions
+++ b/resolv/Versions
@@ -1,5 +1,6 @@
 libc {
   GLIBC_2.0 {
+    __dn_comp;
     __h_errno_location;
     __res_randomid;
     _res;
@@ -42,6 +43,7 @@ libc {
     gai_suspend;
     getaddrinfo_a;
 %endif
+    dn_comp;
     dn_expand;
     ns_name_compress;
     ns_name_ntop;
@@ -79,7 +81,6 @@ libresolv {
   GLIBC_2.0 {
     __b64_ntop;
     __b64_pton;
-    __dn_comp;
     __dn_count_labels;
     __dn_skipname;
     __fp_nquery;
diff --git a/resolv/dn_comp.c b/resolv/dn_comp.c
new file mode 100644
index 0000000000..4506a628ac
--- /dev/null
+++ b/resolv/dn_comp.c
@@ -0,0 +1,103 @@
+/* Compressing a DNS domain name from presentation form to 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 EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Portions Copyright (c) 1993 by Digital Equipment Corporation.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies, and that
+ * the name of Digital Equipment Corporation not be used in advertising or
+ * publicity pertaining to distribution of the document or software without
+ * specific, written prior permission.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
+ * C