build-sys: split _PATH_ADJTIME to two files

This patch introduces:

* _PATH_HWCLOCK_MODE_FILE for clock mode (UTC or LOCAL), default is
   _PATH_ADJTIME (/etc/adjtime).

* _PATH_HWCLOCK_DRIFT_FILE - optional file for clock drift information,
  the default is /var/lib/hwclock/drift. If the file does not exist than
  default to _PATH_HWCLOCK_MODE_FILE.

The both files use 'adjtime' file format for better backward compatibility.

The file /etc/adjtime is de-facto standard and it's used by more 3rd party
utils (e.g. systemd). Unfortunately, keep state files in /etc is bad
idea. This change makes /etc/adjtime read-only for UTC / LOCAL info
and rest is maintained in /var/lib/hwclock/drift.

Note that /var/lib/hwclock/drift is not automatically created. It's up
to downstream (or system admin) to create the file, for example by:

 		cp /etc/adjtime /var/lib/hwclock/drift

otherwise binary will fall back to /etc/adjtime. This idea makes
hwclock backwardly compatible and more portable without recompilation.
(This patch does not implement changes for hwclock.)

Signed-off-by: Karel Zak <kzak@redhat.com>

Makefile.am

@@ -141,6 +141,8 @@ edit_cmd = sed \
 	 -e 's|@usrsbin_execdir[@]|$(usrsbin_execdir)|g' \
 	 -e 's|@VERSION[@]|$(VERSION)|g' \
 	 -e 's|@ADJTIME_PATH[@]|$(ADJTIME_PATH)|g' \
+	 -e 's|@CLOCKMODE_PATH[@]|$(CLOCKMODE_PATH)|g' \
+	 -e 's|@CLOCKDRIFT_PATH[@]|$(CLOCKDRIFT_PATH)|g' \
 	 -e 's|@LIBUUID_VERSION[@]|$(LIBUUID_VERSION)|g' \
 	 -e 's|@LIBMOUNT_VERSION[@]|$(LIBMOUNT_VERSION)|g' \
 	 -e 's|@LIBMOUNT_MAJOR_VERSION[@]|$(LIBMOUNT_MAJOR_VERSION)|g' \

configure.ac

@@ -2572,14 +2572,23 @@ AC_ARG_VAR([SOLIB_LDFLAGS],
 	   [LDFLAGS used for shared libraries])
 
 AC_ARG_VAR([ADJTIME_PATH],
-	   [Path to hwclock adjtime file, default /etc/adjtime])
+	   [Path to adjtime file; fallback if CLOCKMODE_PATH or CLOCKDRIFT_PATH do not exist, default is /etc/adjtime])
 AS_IF([test "x$ADJTIME_PATH" = x], [ADJTIME_PATH="/etc/adjtime"])
-AC_DEFINE_UNQUOTED([CONFIG_ADJTIME_PATH], "$ADJTIME_PATH", [Path to hwclock adjtime file])
+AC_DEFINE_UNQUOTED([CONFIG_ADJTIME_FILE], "$ADJTIME_PATH", [Path to adjtime file])
+
+AC_ARG_VAR([CLOCKMODE_PATH],
+	   [Path to hwclock utc/local setting file, default ADJTIME_PATH])
+AS_IF([test "x$CLOCKMODE_PATH" = x], [CLOCKMODE_PATH=$ADJTIME_PATH])
+AC_DEFINE_UNQUOTED([CONFIG_HWCLOCK_MODE_FILE], "$CLOCKMODE_PATH", [Path to hwclock utc/local mode file])
+
+AC_ARG_VAR([CLOCKDRIFT_PATH],
+	   [Path to hwclock drift status file, default /var/lib/hwclock/drift])
+AS_IF([test "x$CLOCKDRIFT_PATH" = x], [CLOCKDRIFT_PATH="/var/lib/hwclock/drift"])
+AC_DEFINE_UNQUOTED([CONFIG_HWCLOCK_DRIFT_FILE], "$CLOCKDRIFT_PATH", [Path to hwclock drift status file])
 
 
 LIBS=""
 
-
 AC_CONFIG_HEADERS([config.h])
 
 #

include/pathnames.h

@@ -156,11 +156,9 @@
 #define _PATH_DEV_BYPARTUUID	"/dev/disk/by-partuuid"
 
 /* hwclock paths */
-#ifdef CONFIG_ADJTIME_PATH
-# define _PATH_ADJTIME		CONFIG_ADJTIME_PATH
-#else
-# define _PATH_ADJTIME		"/etc/adjtime"
-#endif
+#define _PATH_HWCLOCK_DRIFT_FILE	CONFIG_HWCLOCK_DRIFT_FILE
+#define _PATH_HWCLOCK_MODE_FILE		CONFIG_HWCLOCK_MODE_FILE
+#define _PATH_ADJTIME			CONFIG_ADJTIME_FILE
 
 #ifdef __ia64__
 # define _PATH_RTC_DEV		"/dev/efirtc"

include/timeutils.h

@@ -89,4 +89,8 @@ int strtime_short(const time_t *t, struct timeval *now, int flags, char *buf, si
 extern time_t timegm(struct tm *tm);
 #endif
 
+const char *ul_hwclock_get_drift_file(void);
+const char *ul_hwclock_get_mode_file(void);
+int ul_hwclock_mode_is_utc(const char *modefile, int *rc);
+
 #endif /* UTIL_LINUX_TIME_UTIL_H */

lib/timeutils.c

@@ -29,6 +29,7 @@
 #include "nls.h"
 #include "strutils.h"
 #include "timeutils.h"
+#include "pathnames.h"
 
 #define WHITESPACE " \t\n\r"
 
@@ -568,6 +569,59 @@ time_t timegm(struct tm *tm)
 }
 #endif /* HAVE_TIMEGM */
 
+/* hwclock drift information */
+const char *ul_hwclock_get_drift_file(void)
+{
+	if (access(_PATH_HWCLOCK_DRIFT_FILE, F_OK) == 0)
+		return _PATH_HWCLOCK_DRIFT_FILE;
+
+	return ul_hwclock_get_mode_file();
+}
+
+const char *ul_hwclock_get_mode_file(void)
+{
+	if (strcmp(_PATH_HWCLOCK_MODE_FILE, _PATH_ADJTIME) != 0
+	    && access(_PATH_HWCLOCK_MODE_FILE, F_OK) == 0)
+		return _PATH_HWCLOCK_MODE_FILE;
+
+	return _PATH_ADJTIME;	/* backward compatible default */
+}
+
+int ul_hwclock_mode_is_utc(const char *modefile, int *rc)
+{
+	FILE *fp = NULL;
+	char linebuf[8];
+
+	*rc = EINVAL;
+
+	if (!modefile)
+		modefile = ul_hwclock_get_mode_file();
+
+	fp = fopen(modefile, "r");
+	if (!fp) {
+		*rc = errno;
+		goto dflt;
+	}
+	if (skip_fline(fp) || skip_fline(fp))		/* skip two lines */
+		goto dflt;
+	if (!fgets(linebuf, sizeof linebuf, fp))	/* read 3rd line */
+		goto dflt;
+
+	fclose(fp);
+	fp = NULL;
+
+	if (strncmp(linebuf, "LOCAL", 5) == 0) {
+		*rc = 0;
+		return 0;
+	}
+	if (strncmp(linebuf, "UTC", 3) == 0)
+		*rc = 0;
+dflt:
+	if (fp)
+		fclose(fp);
+	return 1;
+}
+
 #ifdef TEST_PROGRAM_TIMEUTILS
 
 int main(int argc, char *argv[])
@@ -576,16 +630,29 @@ int main(int argc, char *argv[])
 	char buf[ISO_BUFSIZ];
 
 	if (argc < 2) {
-		fprintf(stderr, "usage: %s [<time> [<usec>]] | [--timestamp <str>]\n", argv[0]);
+		fprintf(stderr, "usage: %1$s <time> [<usec>]\n"
+				"       %1$s --timestamp <str>\n"
+				"       %1$s --clockmode\n",
+				argv[0]);
 		exit(EXIT_FAILURE);
 	}
 
-	if (strcmp(argv[1], "--timestamp") == 0) {
+	 if (strcmp(argv[1], "--clockmode") == 0) {
+		int rc = 0,
+		    utc = ul_hwclockmode_is_utc(NULL, &rc);
+
+		printf("%s: mode is %s [rc=%d]\n",
+				ul_hwclock_get_mode_file(),
+				utc ? "UTC" : "LOCAL", rc);
+		return rc ? EXIT_FAILURE : EXIT_SUCCESS;
+
+	} else if (strcmp(argv[1], "--timestamp") == 0) {
 		usec_t usec = 0;
 
 		parse_timestamp(argv[2], &usec);
 		tv.tv_sec = (time_t) (usec / 1000000);
 		tv.tv_usec = usec % 1000000;
+
 	} else {
 		tv.tv_sec = strtos64_or_err(argv[1], "failed to parse <time>");
 		if (argc == 3)