docs/HACKING.md

@@ -2,8 +2,6 @@
 title: Hacking on systemd
 category: Contributing
 layout: default
-redirect_from:
-  - HACKING/
 ---
 
 # Hacking on systemd

docs/UIDS-GIDS.md

@@ -1,10 +1,10 @@
 ---
-title: Users, Groups, UIDs and GIDs on systemd Systems
+title: Users, Groups, UIDs and GIDs on `systemd` Systems
 category: Concepts
 layout: default
 ---
 
-# Users, Groups, UIDs and GIDs on systemd Systems
+# Users, Groups, UIDs and GIDs on `systemd` Systems
 
 Here's a summary of the requirements `systemd` (and Linux) make on UID/GID
 assignments and their ranges.

docs/index.md

@@ -8,6 +8,8 @@ systemd provides aggressive parallelization capabilities, uses socket and D-Bus
 
 Other parts include a logging daemon, utilities to control basic system configuration like the hostname, date, locale, maintain a list of logged-in users and running containers and virtual machines, system accounts, runtime directories and settings, and daemons to manage simple network configuration, network time synchronization, log forwarding, and name resolution.
 
+See the introductory blog story and three status updates for a longer introduction. Also see the [Wikipedia article](https://en.wikipedia.org/wiki/systemd).
+
 ---
 
 {% assign by_category = site.pages | group_by:"category" %}
@@ -22,74 +24,3 @@ Other parts include a logging daemon, utilities to control basic system configur
   {% endif %}
 {% endfor %}
 
-## See also
-
-* [Introductory blog story](http://0pointer.de/blog/projects/systemd.html)
-* [Three](http://0pointer.de/blog/projects/systemd-update.html) [status](http://0pointer.de/blog/projects/systemd-update-2.html) [updates](http://0pointer.de/blog/projects/systemd-update-3.html)
-* The [Wikipedia article](https://en.wikipedia.org/wiki/systemd)
-
----
-
-<pre style="color:white; background-color:black; font-size:smaller; width:45%; padding:6pt 8pt">
-Welcome to <span style="color:blue">Fedora 20 (Heisenbug)</span>!
-
-[  <span style="color:green">OK</span>  ] Reached target Remote File Systems.
-[  <span style="color:green">OK</span>  ] Listening on Delayed Shutdown Socket.
-[  <span style="color:green">OK</span>  ] Listening on /dev/initctl Compatibility Named Pipe.
-[  <span style="color:green">OK</span>  ] Reached target Paths.
-[  <span style="color:green">OK</span>  ] Reached target Encrypted Volumes.
-[  <span style="color:green">OK</span>  ] Listening on Journal Socket.
-         Mounting Huge Pages File System...
-         Mounting POSIX Message Queue File System...
-         Mounting Debug File System...
-         Starting Journal Service...
-[  <span style="color:green">OK</span>  ] Started Journal Service.
-         Mounting Configuration File System...
-         Mounting FUSE Control File System...
-[  <span style="color:green">OK</span>  ] Created slice Root Slice.
-[  <span style="color:green">OK</span>  ] Created slice User and Session Slice.
-[  <span style="color:green">OK</span>  ] Created slice System Slice.
-[  <span style="color:green">OK</span>  ] Reached target Slices.
-[  <span style="color:green">OK</span>  ] Reached target Swap.
-         Mounting Temporary Directory...
-[  <span style="color:green">OK</span>  ] Reached target Local File Systems (Pre).
-         Starting Load Random Seed...
-         Starting Load/Save Random Seed...
-[  <span style="color:green">OK</span>  ] Mounted Huge Pages File System.
-[  <span style="color:green">OK</span>  ] Mounted POSIX Message Queue File System.
-[  <span style="color:green">OK</span>  ] Mounted Debug File System.
-[  <span style="color:green">OK</span>  ] Mounted Configuration File System.
-[  <span style="color:green">OK</span>  ] Mounted FUSE Control File System.
-[  <span style="color:green">OK</span>  ] Mounted Temporary Directory.
-[  <span style="color:green">OK</span>  ] Started Load Random Seed.
-[  <span style="color:green">OK</span>  ] Started Load/Save Random Seed.
-[  <span style="color:green">OK</span>  ] Reached target Local File Systems.
-         Starting Recreate Volatile Files and Directories...
-         Starting Trigger Flushing of Journal to Persistent Storage...
-[  <span style="color:green">OK</span>  ] Started Recreate Volatile Files and Directories.
-         Starting Update UTMP about System Reboot/Shutdown...
-[  <span style="color:green">OK</span>  ] Started Trigger Flushing of Journal to Persistent Storage.
-[  <span style="color:green">OK</span>  ] Started Update UTMP about System Reboot/Shutdown.
-[  <span style="color:green">OK</span>  ] Reached target System Initialization.
-[  <span style="color:green">OK</span>  ] Reached target Timers.
-[  <span style="color:green">OK</span>  ] Listening on D-Bus System Message Bus Socket.
-[  <span style="color:green">OK</span>  ] Reached target Sockets.
-[  <span style="color:green">OK</span>  ] Reached target Basic System.
-         Starting Permit User Sessions...
-         Starting D-Bus System Message Bus...
-[  <span style="color:green">OK</span>  ] Started D-Bus System Message Bus.
-         Starting Login Service...
-         Starting Cleanup of Temporary Directories...
-[  <span style="color:green">OK</span>  ] Started Permit User Sessions.
-[  <span style="color:green">OK</span>  ] Started Cleanup of Temporary Directories.
-         Starting Console Getty...
-[  <span style="color:green">OK</span>  ] Started Console Getty.
-[  <span style="color:green">OK</span>  ] Reached target Login Prompts.
-[  <span style="color:green">OK</span>  ] Started Login Service.
-[  <span style="color:green">OK</span>  ] Reached target Multi-User System.
-
-Fedora release 20 (Heisenbug)
-Kernel 3.9.2-200.fc18.x86_64 on an x86_64 (console)
-
-fedora login:
-</pre>

man/systemd.scope.xml

@@ -46,14 +46,14 @@
     Control Group Interfaces</ulink> for an introduction on how to make
     use of scope units from programs.</para>
 
-    <para>Note that, unlike service units, scope units have no "main" process: all processes in the scope are
+    <para>Note that unlike service units scope units have no "main" process, all processes in the scope are
-    equivalent. The lifecycle of the scope unit is thus not bound to the lifetime of one specific process,
+    equivalent. The lifecycle of the scope unit is thus not bound to the lifetime of one specific process but
-    but to the existence of at least one process in the scope. This also means that the exit statuses of
+    to the existance of any processes in the scope. This also means that the exit status of these processes
-    these processes are not relevant for the scope unit failure state. Scope units may still enter a failure
+    do not cause the scope unit to enter a failure state. Scope units may still enter a failure state, for
-    state, for example due to resource exhaustion or stop timeouts being reached, but not due to programs
+    example due to resource exhaustion or stop timeouts being reached, but not due to programs inside of them
-    inside of them terminating uncleanly. Since processes managed as scope units generally remain children of
+    terminating uncleanly. Since processes managed as scope units generally remain children of the original
-    the original process that forked them off, it is also the job of that process to collect their exit
+    process that forked them off it's also the job of that process to collect their exit statuses and act on
-    statuses and act on them as needed.</para>
+    them as needed.</para>
   </refsect1>
 
   <refsect1>

meson.build

@@ -2993,7 +2993,7 @@ install_data('LICENSE.GPL2',
              'docs/CODING_STYLE.md',
              'docs/DISTRO_PORTING.md',
              'docs/ENVIRONMENT.md',
-             'docs/Hacking.md',
+             'docs/HACKING.md',
              'docs/TRANSIENT-SETTINGS.md',
              'docs/TRANSLATORS.md',
              'docs/UIDS-GIDS.md',

src/core/dbus.c

@@ -719,6 +719,114 @@ static int bus_on_connection(sd_event_source *s, int fd, uint32_t revents, void
         return 0;
 }
 
+static int manager_dispatch_sync_bus_names(sd_event_source *es, void *userdata) {
+        _cleanup_strv_free_ char **names = NULL;
+        Manager *m = userdata;
+        const char *name;
+        Iterator i;
+        Unit *u;
+        int r;
+
+        assert(es);
+        assert(m);
+        assert(m->sync_bus_names_event_source == es);
+
+        /* First things first, destroy the defer event so that we aren't triggered again */
+        m->sync_bus_names_event_source = sd_event_source_unref(m->sync_bus_names_event_source);
+
+        /* Let's see if there's anything to do still? */
+        if (!m->api_bus)
+                return 0;
+        if (hashmap_isempty(m->watch_bus))
+                return 0;
+
+        /* OK, let's sync up the names. Let's see which names are currently on the bus. */
+        r = sd_bus_list_names(m->api_bus, &names, NULL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to get initial list of names: %m");
+
+        /* We have to synchronize the current bus names with the
+         * list of active services. To do this, walk the list of
+         * all units with bus names. */
+        HASHMAP_FOREACH_KEY(u, name, m->watch_bus, i) {
+                Service *s = SERVICE(u);
+
+                assert(s);
+
+                if (!streq_ptr(s->bus_name, name)) {
+                        log_unit_warning(u, "Bus name has changed from %s → %s, ignoring.", s->bus_name, name);
+                        continue;
+                }
+
+                /* Check if a service's bus name is in the list of currently
+                 * active names */
+                if (strv_contains(names, name)) {
+                        _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
+                        const char *unique;
+
+                        /* If it is, determine its current owner */
+                        r = sd_bus_get_name_creds(m->api_bus, name, SD_BUS_CREDS_UNIQUE_NAME, &creds);
+                        if (r < 0) {
+                                log_full_errno(r == -ENXIO ? LOG_DEBUG : LOG_ERR, r, "Failed to get bus name owner %s: %m", name);
+                                continue;
+                        }
+
+                        r = sd_bus_creds_get_unique_name(creds, &unique);
+                        if (r < 0) {
+                                log_full_errno(r == -ENXIO ? LOG_DEBUG : LOG_ERR, r, "Failed to get unique name for %s: %m", name);
+                                continue;
+                        }
+
+                        /* Now, let's compare that to the previous bus owner, and
+                         * if it's still the same, all is fine, so just don't
+                         * bother the service. Otherwise, the name has apparently
+                         * changed, so synthesize a name owner changed signal. */
+
+                        if (!streq_ptr(unique, s->bus_name_owner))
+                                UNIT_VTABLE(u)->bus_name_owner_change(u, s->bus_name_owner, unique);
+                } else {
+                        /* So, the name we're watching is not on the bus.
+                         * This either means it simply hasn't appeared yet,
+                         * or it was lost during the daemon reload.
+                         * Check if the service has a stored name owner,
+                         * and synthesize a name loss signal in this case. */
+
+                        if (s->bus_name_owner)
+                                UNIT_VTABLE(u)->bus_name_owner_change(u, s->bus_name_owner, NULL);
+                }
+        }
+
+        return 0;
+}
+
+int manager_enqueue_sync_bus_names(Manager *m) {
+        int r;
+
+        assert(m);
+
+        /* Enqueues a request to synchronize the bus names in a later event loop iteration. The callers generally don't
+         * want us to invoke ->bus_name_owner_change() unit calls from their stack frames as this might result in event
+         * dispatching on its own creating loops, hence we simply create a defer event for the event loop and exit. */
+
+        if (m->sync_bus_names_event_source)
+                return 0;
+
+        r = sd_event_add_defer(m->event, &m->sync_bus_names_event_source, manager_dispatch_sync_bus_names, m);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create bus name synchronization event: %m");
+
+        r = sd_event_source_set_priority(m->sync_bus_names_event_source, SD_EVENT_PRIORITY_IDLE);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set event priority: %m");
+
+        r = sd_event_source_set_enabled(m->sync_bus_names_event_source, SD_EVENT_ONESHOT);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set even to oneshot: %m");
+
+        (void) sd_event_source_set_description(m->sync_bus_names_event_source, "manager-sync-bus-names");
+        return 0;
+}
+
 static int bus_setup_api(Manager *m, sd_bus *bus) {
         Iterator i;
         char *name;
@@ -802,6 +910,10 @@ int bus_init_api(Manager *m) {
 
         m->api_bus = TAKE_PTR(bus);
 
+        r = manager_enqueue_sync_bus_names(m);
+        if (r < 0)
+                return r;
+
         return 0;
 }
 
@@ -939,10 +1051,13 @@ static void destroy_bus(Manager *m, sd_bus **bus) {
 
         /* Make sure all bus slots watching names are released. */
         HASHMAP_FOREACH(u, m->watch_bus, i) {
-                if (u->match_bus_slot && sd_bus_slot_get_bus(u->match_bus_slot) == *bus)
+                if (!u->match_bus_slot)
+                        continue;
+
+                if (sd_bus_slot_get_bus(u->match_bus_slot) != *bus)
+                        continue;
+
                 u->match_bus_slot = sd_bus_slot_unref(u->match_bus_slot);
-                if (u->get_name_owner_slot && sd_bus_slot_get_bus(u->get_name_owner_slot) == *bus)
-                        u->get_name_owner_slot = sd_bus_slot_unref(u->get_name_owner_slot);
         }
 
         /* Get rid of tracked clients on this bus */

src/core/dbus.h

@@ -21,6 +21,8 @@ int bus_fdset_add_all(Manager *m, FDSet *fds);
 void bus_track_serialize(sd_bus_track *t, FILE *f, const char *prefix);
 int bus_track_coldplug(Manager *m, sd_bus_track **t, bool recursive, char **l);
 
+int manager_enqueue_sync_bus_names(Manager *m);
+
 int bus_foreach_bus(Manager *m, sd_bus_track *subscribed2, int (*send_message)(sd_bus *bus, void *userdata), void *userdata);
 
 int bus_verify_manage_units_async(Manager *m, sd_bus_message *call, sd_bus_error *error);

src/core/manager.c

@@ -1373,6 +1373,7 @@ Manager* manager_free(Manager *m) {
         sd_event_source_unref(m->jobs_in_progress_event_source);
         sd_event_source_unref(m->run_queue_event_source);
         sd_event_source_unref(m->user_lookup_event_source);
+        sd_event_source_unref(m->sync_bus_names_event_source);
 
         safe_close(m->signal_fd);
         safe_close(m->notify_fd);
@@ -1609,6 +1610,9 @@ static void manager_ready(Manager *m) {
         manager_recheck_journal(m);
         manager_recheck_dbus(m);
 
+        /* Sync current state of bus names with our set of listening units */
+        (void) manager_enqueue_sync_bus_names(m);
+
         /* Let's finally catch up with any changes that took place while we were reloading/reexecing */
         manager_catchup(m);
 

src/core/manager.h

@@ -219,6 +219,8 @@ struct Manager {
         int user_lookup_fds[2];
         sd_event_source *user_lookup_event_source;
 
+        sd_event_source *sync_bus_names_event_source;
+
         UnitFileScope unit_file_scope;
         LookupPaths lookup_paths;
         Hashmap *unit_id_map;

src/core/service.c

@@ -4062,17 +4062,24 @@ static int service_get_timeout(Unit *u, usec_t *timeout) {
         return 1;
 }
 
-static void service_bus_name_owner_change(Unit *u, const char *new_owner) {
+static void service_bus_name_owner_change(
+                Unit *u,
+                const char *old_owner,
+                const char *new_owner) {
 
         Service *s = SERVICE(u);
         int r;
 
         assert(s);
 
-        if (new_owner)
+        assert(old_owner || new_owner);
-                log_unit_debug(u, "D-Bus name %s now owned by %s", s->bus_name, new_owner);
+
+        if (old_owner && new_owner)
+                log_unit_debug(u, "D-Bus name %s changed owner from %s to %s", s->bus_name, old_owner, new_owner);
+        else if (old_owner)
+                log_unit_debug(u, "D-Bus name %s no longer registered by %s", s->bus_name, old_owner);
         else
-                log_unit_debug(u, "D-Bus name %s now not owned by anyone.", s->bus_name);
+                log_unit_debug(u, "D-Bus name %s now registered by %s", s->bus_name, new_owner);
 
         s->bus_name_good = !!new_owner;
 

src/core/unit.c

@@ -3201,21 +3201,24 @@ int unit_load_related_unit(Unit *u, const char *type, Unit **_found) {
 }
 
 static int signal_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {
-        const char *new_owner;
+        const char *name, *old_owner, *new_owner;
         Unit *u = userdata;
         int r;
 
         assert(message);
         assert(u);
 
-        r = sd_bus_message_read(message, "sss", NULL, NULL, &new_owner);
+        r = sd_bus_message_read(message, "sss", &name, &old_owner, &new_owner);
         if (r < 0) {
                 bus_log_parse_error(r);
                 return 0;
         }
 
+        old_owner = empty_to_null(old_owner);
+        new_owner = empty_to_null(new_owner);
+
         if (UNIT_VTABLE(u)->bus_name_owner_change)
-                UNIT_VTABLE(u)->bus_name_owner_change(u, empty_to_null(new_owner));
+                UNIT_VTABLE(u)->bus_name_owner_change(u, old_owner, new_owner);
 
         return 0;
 }
@@ -3231,35 +3234,42 @@ static int get_name_owner_handler(sd_bus_message *message, void *userdata, sd_bu
 
         u->get_name_owner_slot = sd_bus_slot_unref(u->get_name_owner_slot);
 
-        e = sd_bus_message_get_error(message);
+        if (sd_bus_error_is_set(error)) {
-        if (e) {
+                log_error("Failed to get name owner from bus: %s", error->message);
-                if (!sd_bus_error_has_name(e, "org.freedesktop.DBus.Error.NameHasNoOwner"))
+                return 0;
-                        log_unit_error(u, "Unexpected error response from GetNameOwner(): %s", e->message);
-
-                new_owner = NULL;
-        } else {
-                r = sd_bus_message_read(message, "s", &new_owner);
-                if (r < 0)
-                        return bus_log_parse_error(r);
-
-                assert(!isempty(new_owner));
         }
 
+        e = sd_bus_message_get_error(message);
+        if (sd_bus_error_has_name(e, "org.freedesktop.DBus.Error.NameHasNoOwner"))
+                return 0;
+
+        if (e) {
+                log_error("Unexpected error response from GetNameOwner: %s", e->message);
+                return 0;
+        }
+
+        r = sd_bus_message_read(message, "s", &new_owner);
+        if (r < 0) {
+                bus_log_parse_error(r);
+                return 0;
+        }
+
+        new_owner = empty_to_null(new_owner);
+
         if (UNIT_VTABLE(u)->bus_name_owner_change)
-                UNIT_VTABLE(u)->bus_name_owner_change(u, new_owner);
+                UNIT_VTABLE(u)->bus_name_owner_change(u, NULL, new_owner);
 
         return 0;
 }
 
 int unit_install_bus_match(Unit *u, sd_bus *bus, const char *name) {
         const char *match;
-        int r;
 
         assert(u);
         assert(bus);
         assert(name);
 
-        if (u->match_bus_slot || u->get_name_owner_slot)
+        if (u->match_bus_slot)
                 return -EBUSY;
 
         match = strjoina("type='signal',"
@@ -3269,12 +3279,11 @@ int unit_install_bus_match(Unit *u, sd_bus *bus, const char *name) {
                          "member='NameOwnerChanged',"
                          "arg0='", name, "'");
 
-        r = sd_bus_add_match_async(bus, &u->match_bus_slot, match, signal_name_owner_changed, NULL, u);
+        int r = sd_bus_add_match_async(bus, &u->match_bus_slot, match, signal_name_owner_changed, NULL, u);
         if (r < 0)
                 return r;
 
-        r = sd_bus_call_method_async(
+        return sd_bus_call_method_async(bus,
-                        bus,
                                         &u->get_name_owner_slot,
                                         "org.freedesktop.DBus",
                                         "/org/freedesktop/DBus",
@@ -3283,13 +3292,6 @@ int unit_install_bus_match(Unit *u, sd_bus *bus, const char *name) {
                                         get_name_owner_handler,
                                         u,
                                         "s", name);
-        if (r < 0) {
-                u->match_bus_slot = sd_bus_slot_unref(u->match_bus_slot);
-                return r;
-        }
-
-        log_unit_debug(u, "Watching D-Bus name '%s'.", name);
-        return 0;
 }
 
 int unit_watch_bus_name(Unit *u, const char *name) {
@@ -3312,7 +3314,6 @@ int unit_watch_bus_name(Unit *u, const char *name) {
         r = hashmap_put(u->manager->watch_bus, name, u);
         if (r < 0) {
                 u->match_bus_slot = sd_bus_slot_unref(u->match_bus_slot);
-                u->get_name_owner_slot = sd_bus_slot_unref(u->get_name_owner_slot);
                 return log_warning_errno(r, "Failed to put bus name to hashmap: %m");
         }
 

src/core/unit.h

@@ -530,7 +530,7 @@ typedef struct UnitVTable {
         void (*notify_message)(Unit *u, const struct ucred *ucred, char **tags, FDSet *fds);
 
         /* Called whenever a name this Unit registered for comes or goes away. */
-        void (*bus_name_owner_change)(Unit *u, const char *new_owner);
+        void (*bus_name_owner_change)(Unit *u, const char *old_owner, const char *new_owner);
 
         /* Called for each property that is being set */
         int (*bus_set_property)(Unit *u, const char *name, sd_bus_message *message, UnitWriteFlags flags, sd_bus_error *error);