Meaningful error codes instead of plain -1

libuavcan/src/protocol/data_type_info_provider.cpp

@@ -84,7 +84,7 @@ void DataTypeInfoProvider::handleGetDataTypeInfoRequest(const protocol::GetDataT
 
 int DataTypeInfoProvider::start()
 {
-    int res = -1;
+    int res = 0;
 
     res = cats_srv_.start(
         ComputeAggregateTypeSignatureCallback(this, &DataTypeInfoProvider::handleComputeAggregateTypeSignatureRequest));

libuavcan/src/protocol/global_time_sync_master.cpp

@@ -108,12 +108,12 @@ int GlobalTimeSyncMaster::init()
         GlobalDataTypeRegistry::instance().find(DataTypeKindMessage, protocol::GlobalTimeSync::getDataTypeFullName());
     if (desc == NULL)
     {
-        return -1;
+        return -ErrUnknownDataType;
     }
     dtid_ = desc->getID();
 
     // Iface master array
-    int res = -1;
+    int res = -ErrLogic;
     for (uint8_t i = 0; i < MaxCanIfaces; i++)
     {
         if (!iface_masters_[i].isConstructed())

libuavcan/src/protocol/node_initializer.cpp

@@ -105,7 +105,7 @@ int NodeInitializer::checkOneNodeOneDataTypeKind(NodeID nid, DataTypeKind kind)
     }
     if (!last_cats_request_ok_)
     {
-        return -1;
+        return -ErrFailure;
     }
     return 0;
 }

libuavcan/src/protocol/node_status_provider.cpp

@@ -59,15 +59,13 @@ void NodeStatusProvider::handleGetNodeInfoRequest(const protocol::GetNodeInfo::R
 
 int NodeStatusProvider::startAndPublish()
 {
-    int res = -1;
-
     if (!isNodeInfoInitialized())
     {
         UAVCAN_TRACE("NodeStatusProvider", "Node info was not initialized");
-        return -1;
+        return -ErrNotInited;
     }
 
-    res = publish(); // Initial broadcast
+    int res = publish(); // Initial broadcast
     if (res < 0)
     {
         goto fail;

libuavcan/src/protocol/param_server.cpp

@@ -73,7 +73,7 @@ int ParamServer::start(IParamManager* manager)
 {
     if (manager == NULL)
     {
-        return -1;
+        return -ErrInvalidParam;
     }
     manager_ = manager;