timedated: manage systemd-timesyncd directly instead of lists of alternatives

Alternative NTP implementations should add a:
  Conflicts=systemd-timesyncd.service
to take over the built-in NTP functionality of systemd.

Makefile.am

@@ -106,7 +106,6 @@ udevrulesdir=$(udevlibexecdir)/rules.d
 udevhwdbdir=$(udevlibexecdir)/hwdb.d
 catalogdir=$(prefix)/lib/systemd/catalog
 kernelinstalldir = $(prefix)/lib/kernel/install.d
-ntpunitsdir=$(prefix)/lib/systemd/ntp-units.d
 
 # And these are the special ones for /
 rootprefix=@rootprefix@
@@ -4320,10 +4319,6 @@ dist_systemunit_DATA += \
 polkitpolicy_files += \
 	src/timedate/org.freedesktop.timedate1.policy
 
-INSTALL_DIRS += \
-	$(prefix)/lib/systemd/ntp-units.d \
-	$(sysconfdir)/systemd/ntp-units.d
-
 SYSTEM_UNIT_ALIASES += \
 	systemd-timedated.service dbus-org.freedesktop.timedate1.service
 
@@ -4397,10 +4392,6 @@ EXTRA_DIST += \
 
 CLEANFILES += \
 	src/timesync/timesyncd.conf
-
-dist_ntpunits_DATA = \
-	src/timesync/90-systemd.list
-
 endif
 
 # ------------------------------------------------------------------------------

NEWS

@@ -1,5 +1,12 @@
 systemd System and Service Manager
 
+CHANGES WITH 216:
+        * timedated does no longer read NTP unit names from
+          /usr/lib/systemd/ntp-units.d/*.list. Alternative NTP
+          implementations should add a:
+            Conflicts=systemd-timesyncd.service
+          to take over and replace systemd's NTP functionality.
+
 CHANGES WITH 215:
 
         * A new tool systemd-sysusers has been added. This tool

src/timedate/timedated.c

@@ -180,68 +180,15 @@ static int context_write_data_local_rtc(Context *c) {
         return write_string_file_atomic_label("/etc/adjtime", w);
 }
 
-static char** get_ntp_services(void) {
-        _cleanup_strv_free_ char **r = NULL, **files = NULL;
-        char **i;
-        int k;
-
-        k = conf_files_list(&files, ".list", NULL,
-                            "/etc/systemd/ntp-units.d",
-                            "/run/systemd/ntp-units.d",
-                            "/usr/local/lib/systemd/ntp-units.d",
-                            "/usr/lib/systemd/ntp-units.d",
-                            NULL);
-        if (k < 0)
-                return NULL;
-
-        STRV_FOREACH(i, files) {
-                _cleanup_fclose_ FILE *f;
-
-                f = fopen(*i, "re");
-                if (!f)
-                        continue;
-
-                for (;;) {
-                        char line[PATH_MAX], *l;
-
-                        if (!fgets(line, sizeof(line), f)) {
-                                if (ferror(f))
-                                        log_error("Failed to read NTP unit file: %m");
-
-                                break;
-                        }
-
-                        l = strstrip(line);
-                        if (l[0] == 0 || l[0] == '#')
-                                continue;
-
-                        if (strv_extend(&r, l) < 0) {
-                                log_oom();
-                                return NULL;
-                        }
-                }
-        }
-
-        i = r;
-        r = NULL; /* avoid cleanup */
-
-        return strv_uniq(i);
-}
-
 static int context_read_ntp(Context *c, sd_bus *bus) {
-        _cleanup_strv_free_ char **l;
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
-        char **i;
+        sd_bus_message *reply = NULL;
+        const char *s;
         int r;
 
         assert(c);
         assert(bus);
 
-        l = get_ntp_services();
-        STRV_FOREACH(i, l) {
-                _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
-                sd_bus_message *reply = NULL;
-                const char *s;
-
         r = sd_bus_call_method(
                         bus,
                         "org.freedesktop.systemd1",
@@ -251,12 +198,13 @@ static int context_read_ntp(Context *c, sd_bus *bus) {
                         &error,
                         &reply,
                         "s",
-                                *i);
+                        "systemd-timesyncd.service");
 
         if (r < 0) {
-                        /* This implementation does not exist. Try the next one. */
+                if (sd_bus_error_has_name(&error, SD_BUS_ERROR_FILE_NOT_FOUND) ||
-                        if (sd_bus_error_has_name(&error, SD_BUS_ERROR_FILE_NOT_FOUND))
+                    sd_bus_error_has_name(&error, "org.freedesktop.systemd1.LoadFailed") ||
-                                continue;
+                    sd_bus_error_has_name(&error, "org.freedesktop.systemd1.NoSuchUnit"))
+                        return 0;
 
                 return r;
         }
@@ -271,21 +219,13 @@ static int context_read_ntp(Context *c, sd_bus *bus) {
         return 0;
 }
 
-        return 0;
-}
-
 static int context_start_ntp(Context *c, sd_bus *bus, sd_bus_error *error) {
-        _cleanup_strv_free_ char **l = NULL;
-        char **i;
         int r;
 
         assert(c);
         assert(bus);
         assert(error);
 
-        l = get_ntp_services();
-        STRV_FOREACH(i, l) {
-
         if (c->use_ntp)
                 r = sd_bus_call_method(
                                 bus,
@@ -295,7 +235,9 @@ static int context_start_ntp(Context *c, sd_bus *bus, sd_bus_error *error) {
                                 "StartUnit",
                                 error,
                                 NULL,
-                                        "ss", *i, "replace");
+                                "ss",
+                                "systemd-timesyncd.service",
+                                "replace");
         else
                 r = sd_bus_call_method(
                                 bus,
@@ -305,38 +247,31 @@ static int context_start_ntp(Context *c, sd_bus *bus, sd_bus_error *error) {
                                 "StopUnit",
                                 error,
                                 NULL,
-                                        "ss", *i, "replace");
+                                "ss",
+                                "systemd-timesyncd.service",
+                                "replace");
 
         if (r < 0) {
                 if (sd_bus_error_has_name(error, SD_BUS_ERROR_FILE_NOT_FOUND) ||
                     sd_bus_error_has_name(error, "org.freedesktop.systemd1.LoadFailed") ||
                     sd_bus_error_has_name(error, "org.freedesktop.systemd1.NoSuchUnit")) {
-                                /* This implementation does not exist. Try the next one. */
+                        sd_bus_error_set_const(error, "org.freedesktop.timedate1.NoNTPSupport", "NTP not supported.");
-                                sd_bus_error_free(error);
+                        return -ENOTSUP;
-                                continue;
                 }
 
                 return r;
         }
 
-                return 1;
+        return 0;
-        }
-
-        sd_bus_error_set_const(error, "org.freedesktop.timedate1.NoNTPSupport", "NTP not supported.");
-        return -ENOTSUP;
 }
 
 static int context_enable_ntp(Context*c, sd_bus *bus, sd_bus_error *error) {
-        _cleanup_strv_free_ char **l = NULL;
-        char **i;
         int r;
 
         assert(c);
         assert(bus);
         assert(error);
 
-        l = get_ntp_services();
-        STRV_FOREACH(i, l) {
         if (c->use_ntp)
                 r = sd_bus_call_method(
                                 bus,
@@ -346,7 +281,9 @@ static int context_enable_ntp(Context*c, sd_bus *bus, sd_bus_error *error) {
                                 "EnableUnitFiles",
                                 error,
                                 NULL,
-                                        "asbb", 1, *i, false, true);
+                                "asbb", 1,
+                                "systemd-timesyncd.service",
+                                false, true);
         else
                 r = sd_bus_call_method(
                                 bus,
@@ -356,13 +293,14 @@ static int context_enable_ntp(Context*c, sd_bus *bus, sd_bus_error *error) {
                                 "DisableUnitFiles",
                                 error,
                                 NULL,
-                                        "asb", 1, *i, false);
+                                "asb", 1,
+                                "systemd-timesyncd.service",
+                                false);
 
         if (r < 0) {
                 if (sd_bus_error_has_name(error, SD_BUS_ERROR_FILE_NOT_FOUND)) {
-                                /* This implementation does not exist. Try the next one. */
+                        sd_bus_error_set_const(error, "org.freedesktop.timedate1.NoNTPSupport", "NTP not supported.");
-                                sd_bus_error_free(error);
+                        return -ENOTSUP;
-                                continue;
                 }
 
                 return r;
@@ -380,11 +318,7 @@ static int context_enable_ntp(Context*c, sd_bus *bus, sd_bus_error *error) {
         if (r < 0)
                 return r;
 
-                return 1;
+        return 0;
-        }
-
-        sd_bus_error_set_const(error, "org.freedesktop.timedate1.NoNTPSupport", "NTP not supported.");
-        return -ENOTSUP;
 }
 
 static int property_get_rtc_time(