unit: allocate bus name match string on the stack

Let's use strjoina() rather than strjoin() for construct dbus match
strings.

Also, while we are at it, fix parameter ordering, so that our functions
always put the object first, like it is customary for OO-like
programming.

1 files changed, 8 insertions, 11 deletions

diff --git a/src/core/unit.c b/src/core/unit.c
index 39cd89f1e3..d8f0eb8111 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -2508,26 +2508,23 @@ static int signal_name_owner_changed(sd_bus_message *message, void *userdata, sd
         return 0;
 }
 
-int unit_install_bus_match(sd_bus *bus, Unit *u, const char *name) {
-        _cleanup_free_ char *match = NULL;
-        Manager *m = u->manager;
+int unit_install_bus_match(Unit *u, sd_bus *bus, const char *name) {
+        const char *match;
 
-        assert(m);
+        assert(u);
+        assert(bus);
+        assert(name);
 
         if (u->match_bus_slot)
                 return -EBUSY;
 
-        match = strjoin("type='signal',"
+        match = strjoina("type='signal',"
                         "sender='org.freedesktop.DBus',"
                         "path='/org/freedesktop/DBus',"
                         "interface='org.freedesktop.DBus',"
                         "member='NameOwnerChanged',"
-                        "arg0='",
-                        name,
-                        "'",
+                        "arg0='", name, "'",
                         NULL);
-        if (!match)
-                return -ENOMEM;
 
         return sd_bus_add_match(bus, &u->match_bus_slot, match, signal_name_owner_changed, u);
 }
@@ -2544,7 +2541,7 @@ int unit_watch_bus_name(Unit *u, const char *name) {
         if (u->manager->api_bus) {
                 /* If the bus is already available, install the match directly.
                  * Otherwise, just put the name in the list. bus_setup_api() will take care later. */
-                r = unit_install_bus_match(u->manager->api_bus, u, name);
+                r = unit_install_bus_match(u, u->manager->api_bus, name);
                 if (r < 0)
                         return log_warning_errno(r, "Failed to subscribe to NameOwnerChanged signal: %m");
         }