time.h: reduce CLOCK_ namespace pollution, move to _clock_id.h

Attempt to comply with the strict namespace pollution requirements of
_POSIX_C_SOURCE. Add guards to limit visitbility of CLOCK_ and TIMER_
defines as appropriate. Only define the CLOCK_ variables relevant to the
specific standards. Move all the sharing to sys/_clock_id.h and make
time.h and sys/time.h both include that rather than copy due to the
now large number of clocks and compat defines.

Please note: The old time.h previously used these newer dates:
	CLOCK_REALTIME			199506
	CLOCK_MONOTONIC			200112
	CLOCK_THREAD_CPUTIME_ID		200112
	CLOCK_PROCESS_CPUTIME_ID	200112

but glibc defines all of these for 199309. glibc uses this date for all
these values, however, only CLOCK_REALTIME was in IEEE 1003.1b. Add a
comment about this to document it. A large number of programs and
libraries assume that these will be defined for _POSIX_C_SOURCE =
199309.

In addition, leak CLOCK_UPTIME_FAST for the pocl package until it can be
updated to use a simple CLOCK_MONOTONIC.

Reviewed by:		kib
Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D31056

include/time.h

@@ -46,6 +46,7 @@
 #include <sys/cdefs.h>
 #include <sys/_null.h>
 #include <sys/_types.h>
+#include <sys/_clock_id.h>
 
 #if __POSIX_VISIBLE > 0 && __POSIX_VISIBLE < 200112 || __BSD_VISIBLE
 /*
@@ -97,35 +98,6 @@ typedef	__pid_t		pid_t;
 #endif
 #endif
 
-/* These macros are also in sys/time.h. */
-#if !defined(CLOCK_REALTIME) && __POSIX_VISIBLE >= 199506
-#define CLOCK_REALTIME	0
-#endif /* !defined(CLOCK_REALTIME) && __POSIX_VISIBLE >= 199506 */
-#if !defined(CLOCK_VIRTUAL) && __BSD_VISIBLE
-#define CLOCK_VIRTUAL	1
-#define CLOCK_PROF	2
-#endif /* !defined(CLOCK_VIRTUAL) && __BSD_VISIBLE */
-#if !defined(CLOCK_MONOTONIC) && __POSIX_VISIBLE >= 200112
-#define CLOCK_MONOTONIC	4
-#define CLOCK_UPTIME	5		/* FreeBSD-specific. */
-#define CLOCK_UPTIME_PRECISE	7	/* FreeBSD-specific. */
-#define CLOCK_UPTIME_FAST	8	/* FreeBSD-specific. */
-#define CLOCK_REALTIME_PRECISE	9	/* FreeBSD-specific. */
-#define CLOCK_REALTIME_FAST	10	/* FreeBSD-specific. */
-#define CLOCK_MONOTONIC_PRECISE	11	/* FreeBSD-specific. */
-#define CLOCK_MONOTONIC_FAST	12	/* FreeBSD-specific. */
-#define CLOCK_SECOND	13		/* FreeBSD-specific. */
-#define CLOCK_THREAD_CPUTIME_ID	14
-#define	CLOCK_PROCESS_CPUTIME_ID	15
-#endif /* !defined(CLOCK_MONOTONIC) && __POSIX_VISIBLE >= 200112 */
-
-#if __BSD_VISIBLE
-#define TIMER_RELTIME	0x0	/* relative timer */
-#endif
-#if !defined(TIMER_ABSTIME) && __POSIX_VISIBLE >= 199506
-#define TIMER_ABSTIME	0x1	/* absolute timer */
-#endif /* !defined(TIMER_ABSTIME) && __POSIX_VISIBLE >= 199506 */
-
 struct tm {
 	int	tm_sec;		/* seconds after the minute [0-60] */
 	int	tm_min;		/* minutes after the hour [0-59] */

sys/sys/_clock_id.h

@@ -0,0 +1,95 @@
+/*-
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright (c) 1989, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * 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.
+ * 3. 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.
+ *
+ *	@(#)time.h	8.3 (Berkeley) 1/21/94
+ */
+
+#ifndef _SYS_SYS__CLOCK_ID_H
+#define	_SYS_SYS__CLOCK_ID_H
+
+/*
+ * These macros are shared between time.h and sys/time.h.
+ */
+
+/*
+ * Note: The values shown below as a comment for the __POSIX_VISIBLE values are
+ * the ones FreeBSD traditionally used based on our reading of the POSIX
+ * standards. However, glibc uses 199309 for all of them, even those many were
+ * not defined there. To remain bug compatible with glibc means more software
+ * that relied on the glibc behavior will compile easily on FreeBSD.
+ *
+ * Also, CLOCK_UPTIME_FAST is improperly visible temporarily for the lang/pocl
+ * port until it can be updated properly. It incorrectly assumes that this was a
+ * standard value. It will be moved back to the __BSD_VISIBLE section once the
+ * issue is corrected.
+ */
+
+#if __POSIX_VISIBLE >= 199309		/* 199506 */
+#define CLOCK_REALTIME		0
+#endif /* __POSIX_VISIBLE >= 199309 */
+#ifdef __BSD_VISIBLE
+#define CLOCK_VIRTUAL		1
+#define CLOCK_PROF		2
+#endif /* __BSD_VISIBLE */
+#if __POSIX_VISIBLE >= 199309		/* 200112 */
+#define CLOCK_MONOTONIC		4
+#define CLOCK_UPTIME_FAST	8
+#endif /* __POSIX_VISIBLE >= 199309 */
+#ifdef __BSD_VISIBLE
+/*
+ * FreeBSD-specific clocks.
+ */
+#define CLOCK_UPTIME		5
+#define CLOCK_UPTIME_PRECISE	7
+#define CLOCK_REALTIME_PRECISE	9
+#define CLOCK_REALTIME_FAST	10
+#define CLOCK_MONOTONIC_PRECISE	11
+#define CLOCK_MONOTONIC_FAST	12
+#define CLOCK_SECOND		13
+#endif /* __BSD_VISIBLE */
+
+#if __POSIX_VISIBLE >= 199309		/* 200112 */
+#define CLOCK_THREAD_CPUTIME_ID	14
+#define	CLOCK_PROCESS_CPUTIME_ID 15
+#endif /* __POSIX_VISIBLE >= 199309 */
+
+#if __BSD_VISIBLE
+#define TIMER_RELTIME	0x0	/* relative timer */
+#endif
+#if __POSIX_VISIBLE >= 199309
+#define TIMER_ABSTIME	0x1	/* absolute timer */
+#endif /* __POSIX_VISIBLE >= 199309 */
+
+#endif /* _SYS_SYS__CLOCK_ID_H */

sys/sys/time.h

@@ -38,6 +38,7 @@
 #include <sys/_timeval.h>
 #include <sys/types.h>
 #include <sys/timespec.h>
+#include <sys/_clock_id.h>
 
 struct timezone {
 	int	tz_minuteswest;	/* minutes west of Greenwich */
@@ -471,33 +472,6 @@ struct clockinfo {
 	int	profhz;		/* profiling clock frequency */
 };
 
-/* These macros are also in time.h. */
-#ifndef CLOCK_REALTIME
-#define	CLOCK_REALTIME	0
-#endif
-#ifndef CLOCK_VIRTUAL
-#define	CLOCK_VIRTUAL	1
-#define	CLOCK_PROF	2
-#endif
-#ifndef CLOCK_MONOTONIC
-#define	CLOCK_MONOTONIC	4
-#define	CLOCK_UPTIME	5		/* FreeBSD-specific. */
-#define	CLOCK_UPTIME_PRECISE	7	/* FreeBSD-specific. */
-#define	CLOCK_UPTIME_FAST	8	/* FreeBSD-specific. */
-#define	CLOCK_REALTIME_PRECISE	9	/* FreeBSD-specific. */
-#define	CLOCK_REALTIME_FAST	10	/* FreeBSD-specific. */
-#define	CLOCK_MONOTONIC_PRECISE	11	/* FreeBSD-specific. */
-#define	CLOCK_MONOTONIC_FAST	12	/* FreeBSD-specific. */
-#define	CLOCK_SECOND	13		/* FreeBSD-specific. */
-#define	CLOCK_THREAD_CPUTIME_ID	14
-#define	CLOCK_PROCESS_CPUTIME_ID	15
-#endif
-
-#ifndef TIMER_ABSTIME
-#define	TIMER_RELTIME	0x0	/* relative timer */
-#define	TIMER_ABSTIME	0x1	/* absolute timer */
-#endif
-
 #if __BSD_VISIBLE
 #define	CPUCLOCK_WHICH_PID	0
 #define	CPUCLOCK_WHICH_TID	1