bus: properly detect and handle if a callback is installed/removed from within a callback

1 files changed, 13 insertions, 0 deletions

diff --git a/src/libsystemd-bus/bus-match.c b/src/libsystemd-bus/bus-match.c
index 972ac8e00e..fed25c1a2a 100644
--- a/src/libsystemd-bus/bus-match.c
+++ b/src/libsystemd-bus/bus-match.c
@@ -212,6 +212,9 @@ int bus_match_run(
         if (!node)
                 return 0;
 
+        if (bus && bus->match_callbacks_modified)
+                return 0;
+
         /* Not these special semantics: when traversing the tree we
          * usually let bus_match_run() when called for a node
          * recursively invoke bus_match_run(). There's are two
@@ -241,6 +244,13 @@ int bus_match_run(
 
         case BUS_MATCH_LEAF:
 
+                if (bus) {
+                        if (node->leaf.last_iteration == bus->iteration_counter)
+                                return 0;
+
+                        node->leaf.last_iteration = bus->iteration_counter;
+                }
+
                 /* Run the callback. And then invoke siblings. */
                 assert(node->leaf.callback);
                 r = node->leaf.callback(bus, ret, m, node->leaf.userdata);
@@ -323,6 +333,9 @@ int bus_match_run(
                 }
         }
 
+        if (bus && bus->match_callbacks_modified)
+                return 0;
+
         /* And now, let's invoke our siblings */
         return bus_match_run(bus, node->next, ret, m);
 }