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>

1 files changed, 48 insertions, 0 deletions

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
+}