Add compat clock_gettime for older macOS. GitHub issue 2555.

compat.h

@@ -265,6 +265,13 @@ void	warnx(const char *, ...);
 #define HOST_NAME_MAX 255
 #endif
 
+#ifndef CLOCK_REALTIME
+#define CLOCK_REALTIME 0
+#endif
+#ifndef CLOCK_MONOTONIC
+#define CLOCK_MONOTONIC CLOCK_REALTIME
+#endif
+
 #ifndef HAVE_FLOCK
 #define LOCK_SH 0
 #define LOCK_EX 0
@@ -342,6 +349,11 @@ const char	*getprogname(void);
 void		 setproctitle(const char *, ...);
 #endif
 
+#ifndef HAVE_CLOCK_GETTIME
+/* clock_gettime.c */
+int		 clock_gettime(int, struct timespec *);
+#endif
+
 #ifndef HAVE_B64_NTOP
 /* base64.c */
 #undef b64_ntop

compat/clock_gettime.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2021 Nicholas Marriott <nicholas.marriott@gmail.com>
+ *
+ * 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.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
+ * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/time.h>
+
+#include "compat.h"
+
+#ifndef TIMEVAL_TO_TIMESPEC
+#define TIMEVAL_TO_TIMESPEC(tv, ts) do {	\
+	(ts)->tv_sec = (tv)->tv_sec;		\
+	(ts)->tv_nsec = (tv)->tv_usec * 1000;	\
+} while (0)
+#endif
+
+int
+clock_gettime(int clock, struct timespec *ts)
+{
+	struct timeval	tv;
+
+	gettimeofday(&tv, NULL);
+	TIMEVAL_TO_TIMESPEC(&tv, ts);
+	return 0;
+}

configure.ac

@@ -133,6 +133,7 @@ AC_CHECK_FUNCS([ \
 AC_REPLACE_FUNCS([ \
 	asprintf \
 	cfmakeraw \
+	clock_gettime \
 	closefrom \
 	explicit_bzero \
 	fgetln \