Fix possible null pointer access

Author: BewareMyPower

lib/ClientImpl.cc

@@ -76,6 +76,12 @@ typedef std::unique_lock<std::mutex> Lock;
 
 typedef std::vector<std::string> StringList;
 
+template <typename T>
+static std::string getName(std::weak_ptr<T> ptr) {
+    auto value = ptr.lock();
+    return value ? value->getName() : "(null)";
+}
+
 ClientImpl::ClientImpl(const std::string& serviceUrl, const ClientConfiguration& clientConfiguration)
     : mutex_(),
       state_(Open),
@@ -226,7 +232,7 @@ void ClientImpl::handleProducerCreated(Result result, ProducerImplBaseWeakPtr pr
         auto existingProducer = producers_.create(address, producer);
         if (existingProducer) {
             LOG_ERROR("Unexpected existing producer at the same address: "
-                      << address << ", producer: " << existingProducer.value().lock()->getProducerName());
+                      << address << ", producer: " << getName(existingProducer.value()));
             callback(ResultUnknownError, {});
             return;
         }
@@ -314,7 +320,7 @@ void ClientImpl::handleReaderMetadataLookup(const Result result, const LookupDat
             auto existingConsumer = consumers_.create(address, consumer);
             if (existingConsumer) {
                 LOG_ERROR("Unexpected existing consumer at the same address: "
-                          << address << ", consumer: " << existingConsumer.value().lock()->getName());
+                          << address << ", consumer: " << getName(existingConsumer.value()));
             }
         } else {
             LOG_ERROR("Unexpected case: the consumer is somehow expired");
@@ -514,7 +520,7 @@ void ClientImpl::handleConsumerCreated(Result result, ConsumerImplBaseWeakPtr co
         auto existingConsumer = consumers_.create(address, consumer);
         if (existingConsumer) {
             LOG_ERROR("Unexpected existing consumer at the same address: "
-                      << address << ", consumer: " << existingConsumer.value().lock()->getName());
+                      << address << ", consumer: " << getName(existingConsumer.value()));
             callback(ResultUnknownError, {});
             return;
         }