sd-event: add a single implementation of an event source that runs on clock changes

We basically had the same code in three places. Let's unify it in a
common helper function.

event_add_time_change() might be something we should add to the official
sd-event API sooner or later, given its general usefulness.

7 files changed, 49 insertions, 36 deletions

diff --git a/src/core/manager.c b/src/core/manager.c
index 4c59506ccb..a4ff2c8355 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -39,6 +39,7 @@
 #include "dirent-util.h"
 #include "env-util.h"
 #include "escape.h"
+#include "event-util.h"
 #include "exec-util.h"
 #include "execute.h"
 #include "exit-status.h"
@@ -406,13 +407,8 @@ static int manager_setup_time_change(Manager *m) {
                 return 0;
 
         m->time_change_event_source = sd_event_source_disable_unref(m->time_change_event_source);
-        m->time_change_fd = safe_close(m->time_change_fd);
 
-        m->time_change_fd = time_change_fd();
-        if (m->time_change_fd < 0)
-                return log_error_errno(m->time_change_fd, "Failed to create timer change timer fd: %m");
-
-        r = sd_event_add_io(m->event, &m->time_change_event_source, m->time_change_fd, EPOLLIN, manager_dispatch_time_change_fd, m);
+        r = event_add_time_change(m->event, &m->time_change_event_source, manager_dispatch_time_change_fd, m);
         if (r < 0)
                 return log_error_errno(r, "Failed to create time change event source: %m");
 
@@ -421,8 +417,6 @@ static int manager_setup_time_change(Manager *m) {
         if (r < 0)
                 return log_error_errno(r, "Failed to set priority of time change event sources: %m");
 
-        (void) sd_event_source_set_description(m->time_change_event_source, "manager-time-change");
-
         log_debug("Set up TFD_TIMER_CANCEL_ON_SET timerfd.");
 
         return 0;
@@ -820,7 +814,6 @@ int manager_new(UnitFileScope scope, ManagerTestRunFlags test_run_flags, Manager
                 .notify_fd = -1,
                 .cgroups_agent_fd = -1,
                 .signal_fd = -1,
-                .time_change_fd = -1,
                 .user_lookup_fds = { -1, -1 },
                 .private_listen_fd = -1,
                 .dev_autofs_fd = -1,
@@ -1509,7 +1502,6 @@ Manager* manager_free(Manager *m) {
         safe_close(m->signal_fd);
         safe_close(m->notify_fd);
         safe_close(m->cgroups_agent_fd);
-        safe_close(m->time_change_fd);
         safe_close_pair(m->user_lookup_fds);
 
         manager_close_ask_password(m);
@@ -2913,7 +2905,6 @@ static int manager_dispatch_time_change_fd(sd_event_source *source, int fd, uint
         Unit *u;
 
         assert(m);
-        assert(m->time_change_fd == fd);
 
         log_struct(LOG_DEBUG,
                    "MESSAGE_ID=" SD_MESSAGE_TIME_CHANGE_STR,
diff --git a/src/core/manager.h b/src/core/manager.h
index e5d988b745..f9096cf348 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -226,7 +226,6 @@ struct Manager {
 
         sd_event_source *sigchld_event_source;
 
-        int time_change_fd;
         sd_event_source *time_change_event_source;
 
         sd_event_source *timezone_change_event_source;
diff --git a/src/libsystemd/sd-event/event-util.c b/src/libsystemd/sd-event/event-util.c
index 0e53406a94..4d0d780741 100644
--- a/src/libsystemd/sd-event/event-util.c
+++ b/src/libsystemd/sd-event/event-util.c
@@ -4,6 +4,7 @@
 
 #include "event-source.h"
 #include "event-util.h"
+#include "fd-util.h"
 #include "log.h"
 #include "string-util.h"
 
@@ -121,3 +122,41 @@ int event_source_is_enabled(sd_event_source *s) {
 
         return sd_event_source_get_enabled(s, NULL);
 }
+
+int event_add_time_change(sd_event *e, sd_event_source **ret, sd_event_io_handler_t callback, void *userdata) {
+        _cleanup_(sd_event_source_disable_unrefp) sd_event_source *s = NULL;
+        _cleanup_close_ int fd = -1;
+        int r;
+
+        assert(e);
+
+        /* Allocates an IO event source that gets woken up whenever the clock changes. Needs to be recreated on each event */
+
+        fd = time_change_fd();
+        if (fd < 0)
+                return fd;
+
+        r = sd_event_add_io(e, &s, fd, EPOLLIN, callback, userdata);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_io_fd_own(s, true);
+        if (r < 0)
+                return r;
+
+        TAKE_FD(fd);
+
+        r = sd_event_source_set_description(s, "time-change");
+        if (r < 0)
+                return r;
+
+        if (ret)
+                *ret = TAKE_PTR(s);
+        else {
+                r = sd_event_source_set_floating(s, true);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
diff --git a/src/libsystemd/sd-event/event-util.h b/src/libsystemd/sd-event/event-util.h
index 64a4199244..abd043bdcc 100644
--- a/src/libsystemd/sd-event/event-util.h
+++ b/src/libsystemd/sd-event/event-util.h
@@ -29,3 +29,5 @@ int event_reset_time_relative(
                 bool force_reset);
 int event_source_disable(sd_event_source *s);
 int event_source_is_enabled(sd_event_source *s);
+
+int event_add_time_change(sd_event *e, sd_event_source **ret, sd_event_io_handler_t callback, void *userdata);
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 615431ebb7..221d0afbdb 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -13,6 +13,7 @@
 #include "bus-polkit.h"
 #include "dirent-util.h"
 #include "dns-domain.h"
+#include "event-util.h"
 #include "fd-util.h"
 #include "fileio.h"
 #include "hostname-util.h"
@@ -338,28 +339,16 @@ static int on_clock_change(sd_event_source *source, int fd, uint32_t revents, vo
 }
 
 static int manager_clock_change_listen(Manager *m) {
-        _cleanup_close_ int fd = -1;
         int r;
 
         assert(m);
 
         m->clock_change_event_source = sd_event_source_disable_unref(m->clock_change_event_source);
 
-        fd = time_change_fd();
-        if (fd < 0)
-                return log_error_errno(fd, "Failed to allocate clock change timer fd: %m");
-
-        r = sd_event_add_io(m->event, &m->clock_change_event_source, fd, EPOLLIN, on_clock_change, m);
+        r = event_add_time_change(m->event, &m->clock_change_event_source, on_clock_change, m);
         if (r < 0)
                 return log_error_errno(r, "Failed to create clock change event source: %m");
 
-        r = sd_event_source_set_io_fd_own(m->clock_change_event_source, true);
-        if (r < 0)
-                return log_error_errno(r, "Failed to pass ownership of clock fd to event source: %m");
-        TAKE_FD(fd);
-
-        (void) sd_event_source_set_description(m->clock_change_event_source, "clock-change");
-
         return 0;
 }
 
diff --git a/src/timesync/timesyncd-manager.c b/src/timesync/timesyncd-manager.c
index 3ab08a0fd6..193d13742b 100644
--- a/src/timesync/timesyncd-manager.c
+++ b/src/timesync/timesyncd-manager.c
@@ -14,6 +14,7 @@
 
 #include "alloc-util.h"
 #include "dns-domain.h"
+#include "event-util.h"
 #include "fd-util.h"
 #include "format-util.h"
 #include "fs-util.h"
@@ -229,14 +230,9 @@ static int manager_clock_watch_setup(Manager *m) {
 
         assert(m);
 
-        m->event_clock_watch = sd_event_source_unref(m->event_clock_watch);
-        safe_close(m->clock_watch_fd);
+        m->event_clock_watch = sd_event_source_disable_unref(m->event_clock_watch);
 
-        m->clock_watch_fd = time_change_fd();
-        if (m->clock_watch_fd < 0)
-                return log_error_errno(m->clock_watch_fd, "Failed to create timerfd: %m");
-
-        r = sd_event_add_io(m->event, &m->event_clock_watch, m->clock_watch_fd, EPOLLIN, manager_clock_watch, m);
+        r = event_add_time_change(m->event, &m->event_clock_watch, manager_clock_watch, m);
         if (r < 0)
                 return log_error_errno(r, "Failed to create clock watch event source: %m");
 
@@ -889,8 +885,7 @@ void manager_disconnect(Manager *m) {
 
         manager_listen_stop(m);
 
-        m->event_clock_watch = sd_event_source_unref(m->event_clock_watch);
-        m->clock_watch_fd = safe_close(m->clock_watch_fd);
+        m->event_clock_watch = sd_event_source_disable_unref(m->event_clock_watch);
 
         m->event_timeout = sd_event_source_unref(m->event_timeout);
 
@@ -1089,7 +1084,6 @@ int manager_new(Manager **ret) {
                 .connection_retry_usec = DEFAULT_CONNECTION_RETRY_USEC,
 
                 .server_socket = -1,
-                .clock_watch_fd = -1,
 
                 .ratelimit = (RateLimit) {
                         RATELIMIT_INTERVAL_USEC,
diff --git a/src/timesync/timesyncd-manager.h b/src/timesync/timesyncd-manager.h
index aceb0098ce..5368dba98c 100644
--- a/src/timesync/timesyncd-manager.h
+++ b/src/timesync/timesyncd-manager.h
@@ -92,7 +92,6 @@ struct Manager {
 
         /* watch for time changes */
         sd_event_source *event_clock_watch;
-        int clock_watch_fd;
 
         /* Retry connections */
         sd_event_source *event_retry;