jmuehlner commented on code in PR #455:
URL: https://github.com/apache/guacamole-server/pull/455#discussion_r1308031814
##########
src/libguac/client.c:
##########
@@ -169,35 +290,56 @@ guac_client* guac_client_alloc() {
client->__output_streams[i].index = GUAC_CLIENT_CLOSED_STREAM_INDEX;
}
-
/* Init locks */
- pthread_rwlockattr_init(&lock_attributes);
- pthread_rwlockattr_setpshared(&lock_attributes, PTHREAD_PROCESS_SHARED);
+ guac_init_reentrant_rwlock(&(client->__users_lock));
+ guac_init_reentrant_rwlock(&(client->__pending_users_lock));
- pthread_rwlock_init(&(client->__users_lock), &lock_attributes);
+ /* Initialize the write lock flags to 0, as threads won't have yet */
+ pthread_key_create(&(client->__users_lock.key), (void *) 0);
+ pthread_key_create(&(client->__pending_users_lock.key), (void *) 0);
- /* Set up socket to broadcast to all users */
+ /* The timer will be lazily created in the child process */
+ client->__pending_users_timer_state =
GUAC_CLIENT_PENDING_TIMER_UNREGISTERED;
+
+ /* Set up the pending user promotion mutex */
+ pthread_mutex_init(&(client->__pending_users_timer_mutex), NULL);
+
+ /* Set up broadcast sockets */
client->socket = guac_socket_broadcast(client);
+ client->pending_socket = guac_socket_broadcast_pending(client);
return client;
}
void guac_client_free(guac_client* client) {
+ /* Acquire write locks before referencing user pointers */
Review Comment:
Added this extra locking layer here because it's not really valid to
reference the `__users` or `__pending_users` fields without holding these
locks.
I had thought about using `guac_client_remove_user` as a callback for
`guac_client_foreach_user` and `guac_client_foreach_pending_user`, which is a
more standard way of doing things, but that would also mean that'd be acquiring
the read lock first, and upgrading to the write lock inside
`guac_client_remove_user()`, which should technically work but should probably
be avoided.
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