machined: keep track of the initial leader PID of a machine

This way we can without races always determine the machine for a leader
PID. This allows machine managers to query the machine for a forked off
container/VM  without a race where the child might already have died
before we could read the cgroup information from /proc/$PID/cgroup.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/machine/machine.c b/src/machine/machine.c
index a33a111043..cf3ef15456 100644
--- a/src/machine/machine.c
+++ b/src/machine/machine.c
@@ -85,6 +85,9 @@ void machine_free(Machine *m) {
 
         hashmap_remove(m->manager->machines, m->name);
 
+        if (m->leader > 0)
+                hashmap_remove_value(m->manager->machine_leaders, UINT_TO_PTR(m->leader), m);
+
         sd_bus_message_unref(m->create_message);
 
         free(m->name);
@@ -263,6 +266,10 @@ int machine_start(Machine *m, sd_bus_message *properties, sd_bus_error *error) {
         if (m->started)
                 return 0;
 
+        r = hashmap_put(m->manager->machine_leaders, UINT_TO_PTR(m->leader), m);
+        if (r < 0)
+                return r;
+
         /* Create cgroup */
         r = machine_start_scope(m, properties, error);
         if (r < 0)