nscd: Do not rebuild getaddrinfo (bug 30709)

The nscd daemon caches hosts data from NSS modules verbatim, without
filtering protocol families or sorting them (otherwise separate caches
would be needed for certain ai_flags combinations).  The cache
implementation is complete separate from the getaddrinfo code.  This
means that rebuilding getaddrinfo is not needed.  The only function
actually used is __bump_nl_timestamp from check_pf.c, and this change
moves it into nscd/connections.c.

Tested on x86_64-linux-gnu with -fexceptions, built with
build-many-glibcs.py.  I also backported this patch into a distribution
that still supports nscd and verified manually that caching still works.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

3 files changed, 12 insertions, 51 deletions

diff --git a/nscd/Makefile b/nscd/Makefile
index 2a0489f4cf..16b6460ee9 100644
--- a/nscd/Makefile
+++ b/nscd/Makefile
@@ -35,7 +35,7 @@ nscd-modules := nscd connections pwdcache getpwnam_r getpwuid_r grpcache \
 		getgrnam_r getgrgid_r hstcache gethstbyad_r gethstbynm3_r \
 		getsrvbynm_r getsrvbypt_r servicescache \
 		dbg_log nscd_conf nscd_stat cache mem nscd_setup_thread \
-		xmalloc xstrdup aicache initgrcache gai res_hconf \
+		xmalloc xstrdup aicache initgrcache res_hconf \
 		netgroupcache cachedumper
 
 ifeq ($(build-nscd)$(have-thread-library),yesyes)
diff --git a/nscd/connections.c b/nscd/connections.c
index a405a44a9b..15693e5090 100644
--- a/nscd/connections.c
+++ b/nscd/connections.c
@@ -256,6 +256,17 @@ int inotify_fd = -1;
 #ifdef HAVE_NETLINK
 /* Descriptor for netlink status updates.  */
 static int nl_status_fd = -1;
+
+static uint32_t
+__bump_nl_timestamp (void)
+{
+  static uint32_t nl_timestamp;
+
+  if (atomic_fetch_add_relaxed (&nl_timestamp, 1) + 1 == 0)
+    atomic_fetch_add_relaxed (&nl_timestamp, 1);
+
+  return nl_timestamp;
+}
 #endif
 
 /* Number of times clients had to wait.  */
diff --git a/nscd/gai.c b/nscd/gai.c
deleted file mode 100644
index e29f3fe583..0000000000
--- a/nscd/gai.c
+++ /dev/null
@@ -1,50 +0,0 @@
-/* Copyright (C) 2004-2023 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published
-   by the Free Software Foundation; version 2 of the License, or
-   (at your option) any later version.
-
-   This program 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 General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, see <https://www.gnu.org/licenses/>.  */
-
-#include <alloca.h>
-#include <sys/stat.h>
-
-/* This file uses the getaddrinfo code but it compiles it without NSCD
-   support.  We just need a few symbol renames.  */
-#define __ioctl ioctl
-#define __getsockname getsockname
-#define __socket socket
-#define __recvmsg recvmsg
-#define __bind bind
-#define __sendto sendto
-#define __strchrnul strchrnul
-#define __getline getline
-#define __qsort_r qsort_r
-/* nscd uses 1MB or 2MB thread stacks.  */
-#define __libc_use_alloca(size) (size <= __MAX_ALLOCA_CUTOFF)
-#define __getifaddrs getifaddrs
-#define __freeifaddrs freeifaddrs
-#undef __fstat64
-#define __fstat64 fstat64
-#undef __stat64
-#define __stat64 stat64
-
-/* We are nscd, so we don't want to be talking to ourselves.  */
-#undef  USE_NSCD
-
-#include <getaddrinfo.c>
-
-/* Support code.  */
-#include <check_pf.c>
-#include <check_native.c>
-
-/* Some variables normally defined in libc.  */
-nss_action_list __nss_hosts_database attribute_hidden;