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core: create/remove unit bus name slots always together

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When a service unit watches a bus name (i.e. because of BusName= being
set), then we do two things: we install a match slot to watch how its
ownership changes, and we inquire about the current owner. Make sure we
always do both together or neither.

This in particular fixes a corner-case memleak when destroying bus
connections, since we never freed the GetNameOwner() bus slots when
destroying a bus when they were still ongoing.
This commit is contained in:
Lennart Poettering 2019-12-23 16:48:18 +01:00
parent 5085ef0d71
commit a5b0784795
2 changed files with 25 additions and 18 deletions
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11
src/core/dbus.c
View file

@ -1051,13 +1051,10 @@ 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)
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->match_bus_slot && sd_bus_slot_get_bus(u->match_bus_slot) == *bus)
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 */

32
src/core/unit.c
View file

@ -3238,12 +3238,13 @@ static int get_name_owner_handler(sd_bus_message *message, void *userdata, sd_bu
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)
if (u->match_bus_slot || u->get_name_owner_slot)
return -EBUSY;
match = strjoina("type='signal',"
@ -3253,19 +3254,27 @@ int unit_install_bus_match(Unit *u, sd_bus *bus, const char *name) {
"member='NameOwnerChanged',"
"arg0='", name, "'");
int r = sd_bus_add_match_async(bus, &u->match_bus_slot, match, signal_name_owner_changed, NULL, u);
r = sd_bus_add_match_async(bus, &u->match_bus_slot, match, signal_name_owner_changed, NULL, u);
if (r < 0)
return r;
return sd_bus_call_method_async(bus,
&u->get_name_owner_slot,
"org.freedesktop.DBus",
"/org/freedesktop/DBus",
"org.freedesktop.DBus",
"GetNameOwner",
get_name_owner_handler,
u,
"s", name);
r = sd_bus_call_method_async(
bus,
&u->get_name_owner_slot,
"org.freedesktop.DBus",
"/org/freedesktop/DBus",
"org.freedesktop.DBus",
"GetNameOwner",
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) {
@ -3288,6 +3297,7 @@ 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");
}