support: Add support_socket_so_timestamp_time64

Check if the socket support 64-bit network packages timestamps
(SO_TIMESTAMP and SO_TIMESTAMPNS).  This will be used on recvmsg
and recvmmsg tests to check if the timestamp should be generated.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

(cherry picked from 38bc0f4e78934aab455b31af05cefcbf3c22bece)

(cherry picked from commit e09e7b1492b2d5c2f68ddf81f8f58e093dd4df6d)

3 files changed, 53 insertions, 0 deletions

diff --git a/support/Makefile b/support/Makefile
index 2a0731796f..724ae6d712 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -78,6 +78,7 @@ libsupport-routines = \
   support_set_small_thread_stack_size \
   support_shared_allocate \
   support_small_stack_thread_attribute \
+  support_socket_so_timestamp_time64 \
   support_stat_nanoseconds \
   support_subprocess \
   support_test_compare_blob \
diff --git a/support/support.h b/support/support.h
index c219e0d9d1..309be85b09 100644
--- a/support/support.h
+++ b/support/support.h
@@ -164,6 +164,10 @@ extern bool support_select_modifies_timeout (void);
    tv_usec larger than 1000000.  */
 extern bool support_select_normalizes_timeout (void);
 
+/* Return true if socket FD supports 64-bit timestamps with the SOL_SOCKET
+   and SO_TIMESTAMP/SO_TIMESTAMPNS.  */
+extern bool support_socket_so_timestamp_time64 (int fd);
+
 /* Create a timer that trigger after SEC seconds and NSEC nanoseconds.  If
    REPEAT is true the timer will repeat indefinitely.  If CALLBACK is not
    NULL, the function will be called when the timer expires; otherwise a
diff --git a/support/support_socket_so_timestamp_time64.c b/support/support_socket_so_timestamp_time64.c
new file mode 100644
index 0000000000..54bf3f4272
--- /dev/null
+++ b/support/support_socket_so_timestamp_time64.c
@@ -0,0 +1,48 @@
+/* Return whether socket supports 64-bit timestamps.
+   Copyright (C) 2022 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/>.  */
+
+#include <errno.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/socket.h>
+#include <support/support.h>
+#ifdef __linux__
+# include <socket-constants-time64.h>
+#endif
+
+bool
+support_socket_so_timestamp_time64 (int fd)
+{
+#ifdef __linux__
+# if __LINUX_KERNEL_VERSION >= 0x050100                          \
+   || __WORDSIZE == 64                                           \
+   || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
+  return true;
+# else
+  int level = SOL_SOCKET;
+  int optname = COMPAT_SO_TIMESTAMP_NEW;
+  int optval;
+  socklen_t len = sizeof (optval);
+
+  int r = syscall (__NR_getsockopt, fd, level, optname, &optval, &len);
+  return r != -1;
+# endif
+#else
+  return false;
+#endif
+}