libnm: add and use _nml_coerce_property_*()th/libnm-various-fixes

Our NMObject implementations should behave in a similar manner.
For example, string properties should be coerced the a consistent
manner.

Add functions _nml_coerce_property_*() for that. Of course, they
are trivial. Their value is not that they encapsulate some complex
implementation, but that they convey a general concept of how we
want to handle certain properties in NMClient's object cache.

24 files changed, 74 insertions, 43 deletions

diff --git a/libnm/nm-access-point.c b/libnm/nm-access-point.c
index 58def0368c..d21bb60acc 100644
--- a/libnm/nm-access-point.c
+++ b/libnm/nm-access-point.c
@@ -163,7 +163,7 @@ nm_access_point_get_bssid (NMAccessPoint *ap)
 {
 	g_return_val_if_fail (NM_IS_ACCESS_POINT (ap), NULL);
 
-	return nm_str_not_empty (NM_ACCESS_POINT_GET_PRIVATE (ap)->bssid);
+	return _nml_coerce_property_str_not_empty (NM_ACCESS_POINT_GET_PRIVATE (ap)->bssid);
 }
 
 /**
diff --git a/libnm/nm-active-connection.c b/libnm/nm-active-connection.c
index c52c2cf54d..6b49f9a5e0 100644
--- a/libnm/nm-active-connection.c
+++ b/libnm/nm-active-connection.c
@@ -109,7 +109,7 @@ nm_active_connection_get_id (NMActiveConnection *connection)
 {
 	g_return_val_if_fail (NM_IS_ACTIVE_CONNECTION (connection), NULL);
 
-	return nm_str_not_empty (NM_ACTIVE_CONNECTION_GET_PRIVATE (connection)->id);
+	return _nml_coerce_property_str_not_empty (NM_ACTIVE_CONNECTION_GET_PRIVATE (connection)->id);
 }
 
 /**
@@ -126,7 +126,7 @@ nm_active_connection_get_uuid (NMActiveConnection *connection)
 {
 	g_return_val_if_fail (NM_IS_ACTIVE_CONNECTION (connection), NULL);
 
-	return nm_str_not_empty (NM_ACTIVE_CONNECTION_GET_PRIVATE (connection)->uuid);
+	return _nml_coerce_property_str_not_empty (NM_ACTIVE_CONNECTION_GET_PRIVATE (connection)->uuid);
 }
 
 /**
@@ -143,7 +143,7 @@ nm_active_connection_get_connection_type (NMActiveConnection *connection)
 {
 	g_return_val_if_fail (NM_IS_ACTIVE_CONNECTION (connection), NULL);
 
-	return nm_str_not_empty (NM_ACTIVE_CONNECTION_GET_PRIVATE (connection)->type);
+	return _nml_coerce_property_str_not_empty (NM_ACTIVE_CONNECTION_GET_PRIVATE (connection)->type);
 }
 
 /**
diff --git a/libnm/nm-device-bond.c b/libnm/nm-device-bond.c
index b62d829b57..880c4f94b8 100644
--- a/libnm/nm-device-bond.c
+++ b/libnm/nm-device-bond.c
@@ -56,7 +56,7 @@ nm_device_bond_get_hw_address (NMDeviceBond *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_BOND (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_BOND_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_BOND_GET_PRIVATE (device)->hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-bridge.c b/libnm/nm-device-bridge.c
index c4fc6e557b..8c3db03e9c 100644
--- a/libnm/nm-device-bridge.c
+++ b/libnm/nm-device-bridge.c
@@ -56,7 +56,7 @@ nm_device_bridge_get_hw_address (NMDeviceBridge *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_BRIDGE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_BRIDGE_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_BRIDGE_GET_PRIVATE (device)->hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-bt.c b/libnm/nm-device-bt.c
index e3d9d4559f..d1600a4277 100644
--- a/libnm/nm-device-bt.c
+++ b/libnm/nm-device-bt.c
@@ -57,7 +57,7 @@ nm_device_bt_get_hw_address (NMDeviceBt *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_BT (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_BT_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_BT_GET_PRIVATE (device)->hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-dummy.c b/libnm/nm-device-dummy.c
index 7a56d53b99..a7f375fdf1 100644
--- a/libnm/nm-device-dummy.c
+++ b/libnm/nm-device-dummy.c
@@ -52,7 +52,7 @@ nm_device_dummy_get_hw_address (NMDeviceDummy *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_DUMMY (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_DUMMY_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_DUMMY_GET_PRIVATE (device)->hw_address);
 }
 
 static gboolean
diff --git a/libnm/nm-device-ethernet.c b/libnm/nm-device-ethernet.c
index 28d3a1076a..94ec318ed6 100644
--- a/libnm/nm-device-ethernet.c
+++ b/libnm/nm-device-ethernet.c
@@ -61,7 +61,7 @@ nm_device_ethernet_get_hw_address (NMDeviceEthernet *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_ETHERNET (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_ETHERNET_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_ETHERNET_GET_PRIVATE (device)->hw_address);
 }
 
 /**
@@ -78,7 +78,7 @@ nm_device_ethernet_get_permanent_hw_address (NMDeviceEthernet *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_ETHERNET (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_ETHERNET_GET_PRIVATE (device)->perm_hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_ETHERNET_GET_PRIVATE (device)->perm_hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-generic.c b/libnm/nm-device-generic.c
index cdc92351a0..f8c4d25737 100644
--- a/libnm/nm-device-generic.c
+++ b/libnm/nm-device-generic.c
@@ -52,7 +52,7 @@ nm_device_generic_get_hw_address (NMDeviceGeneric *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_GENERIC (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GENERIC_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GENERIC_GET_PRIVATE (device)->hw_address);
 }
 
 /*****************************************************************************/
@@ -62,7 +62,7 @@ get_type_description (NMDevice *device)
 {
 	NMDeviceGenericPrivate *priv = NM_DEVICE_GENERIC_GET_PRIVATE (device);
 
-	return nm_str_not_empty (priv->type_description);
+	return _nml_coerce_property_str_not_empty (priv->type_description);
 }
 
 static const char *
diff --git a/libnm/nm-device-infiniband.c b/libnm/nm-device-infiniband.c
index 5c750e7ac7..b48431a91c 100644
--- a/libnm/nm-device-infiniband.c
+++ b/libnm/nm-device-infiniband.c
@@ -53,7 +53,7 @@ nm_device_infiniband_get_hw_address (NMDeviceInfiniband *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_INFINIBAND (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_INFINIBAND_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_INFINIBAND_GET_PRIVATE (device)->hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-ip-tunnel.c b/libnm/nm-device-ip-tunnel.c
index 2f38071ace..3408dd28f0 100644
--- a/libnm/nm-device-ip-tunnel.c
+++ b/libnm/nm-device-ip-tunnel.c
@@ -105,7 +105,7 @@ nm_device_ip_tunnel_get_local (NMDeviceIPTunnel *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_IP_TUNNEL (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->local);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->local);
 }
 
 /**
@@ -121,7 +121,7 @@ nm_device_ip_tunnel_get_remote (NMDeviceIPTunnel *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_IP_TUNNEL (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->remote);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->remote);
 }
 
 /**
@@ -186,7 +186,7 @@ nm_device_ip_tunnel_get_input_key (NMDeviceIPTunnel *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_IP_TUNNEL (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->input_key);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->input_key);
 }
 
 /**
@@ -202,7 +202,7 @@ nm_device_ip_tunnel_get_output_key (NMDeviceIPTunnel *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_IP_TUNNEL (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->output_key);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_IP_TUNNEL_GET_PRIVATE (device)->output_key);
 }
 
 /**
diff --git a/libnm/nm-device-macvlan.c b/libnm/nm-device-macvlan.c
index d511b0b65c..59565b64a1 100644
--- a/libnm/nm-device-macvlan.c
+++ b/libnm/nm-device-macvlan.c
@@ -77,7 +77,7 @@ nm_device_macvlan_get_mode (NMDeviceMacvlan *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_MACVLAN (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_MACVLAN_GET_PRIVATE (device)->mode);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_MACVLAN_GET_PRIVATE (device)->mode);
 }
 
 /**
diff --git a/libnm/nm-device-olpc-mesh.c b/libnm/nm-device-olpc-mesh.c
index 367580bbbd..4d81abcc53 100644
--- a/libnm/nm-device-olpc-mesh.c
+++ b/libnm/nm-device-olpc-mesh.c
@@ -55,7 +55,7 @@ nm_device_olpc_mesh_get_hw_address (NMDeviceOlpcMesh *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_OLPC_MESH (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_OLPC_MESH_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_OLPC_MESH_GET_PRIVATE (device)->hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-team.c b/libnm/nm-device-team.c
index 49c3aad2d8..08b3b082c1 100644
--- a/libnm/nm-device-team.c
+++ b/libnm/nm-device-team.c
@@ -58,7 +58,7 @@ nm_device_team_get_hw_address (NMDeviceTeam *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_TEAM (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_TEAM_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_TEAM_GET_PRIVATE (device)->hw_address);
 }
 
 /**
@@ -111,7 +111,7 @@ nm_device_team_get_config (NMDeviceTeam *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_TEAM (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_TEAM_GET_PRIVATE (device)->config);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_TEAM_GET_PRIVATE (device)->config);
 }
 
 static const char *
diff --git a/libnm/nm-device-tun.c b/libnm/nm-device-tun.c
index e3b36d767e..220c9a2980 100644
--- a/libnm/nm-device-tun.c
+++ b/libnm/nm-device-tun.c
@@ -67,7 +67,7 @@ nm_device_tun_get_hw_address (NMDeviceTun *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_TUN (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_TUN_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_TUN_GET_PRIVATE (device)->hw_address);
 }
 
 /**
@@ -85,7 +85,7 @@ nm_device_tun_get_mode (NMDeviceTun *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_TUN (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_TUN_GET_PRIVATE (device)->mode);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_TUN_GET_PRIVATE (device)->mode);
 }
 
 /**
diff --git a/libnm/nm-device-vlan.c b/libnm/nm-device-vlan.c
index 323d5b30e6..ebe9f00cbe 100644
--- a/libnm/nm-device-vlan.c
+++ b/libnm/nm-device-vlan.c
@@ -58,7 +58,7 @@ nm_device_vlan_get_hw_address (NMDeviceVlan *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_VLAN (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_VLAN_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_VLAN_GET_PRIVATE (device)->hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-vxlan.c b/libnm/nm-device-vxlan.c
index f63e1bdf57..27d7db1d7e 100644
--- a/libnm/nm-device-vxlan.c
+++ b/libnm/nm-device-vxlan.c
@@ -86,7 +86,7 @@ nm_device_vxlan_get_hw_address (NMDeviceVxlan *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_VXLAN (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_VXLAN_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_VXLAN_GET_PRIVATE (device)->hw_address);
 }
 
 /**
@@ -156,7 +156,7 @@ nm_device_vxlan_get_group (NMDeviceVxlan *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_VXLAN (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_VXLAN_GET_PRIVATE (device)->group);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_VXLAN_GET_PRIVATE (device)->group);
 }
 
 /**
@@ -172,7 +172,7 @@ nm_device_vxlan_get_local (NMDeviceVxlan *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_VXLAN (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_VXLAN_GET_PRIVATE (device)->local);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_VXLAN_GET_PRIVATE (device)->local);
 }
 
 /**
diff --git a/libnm/nm-device-wifi-p2p.c b/libnm/nm-device-wifi-p2p.c
index c4fc142c55..92652b3841 100644
--- a/libnm/nm-device-wifi-p2p.c
+++ b/libnm/nm-device-wifi-p2p.c
@@ -73,7 +73,7 @@ nm_device_wifi_p2p_get_hw_address (NMDeviceWifiP2P *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_WIFI_P2P (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_WIFI_P2P_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_WIFI_P2P_GET_PRIVATE (device)->hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-wifi.c b/libnm/nm-device-wifi.c
index d358256060..36b26561c2 100644
--- a/libnm/nm-device-wifi.c
+++ b/libnm/nm-device-wifi.c
@@ -92,7 +92,7 @@ nm_device_wifi_get_hw_address (NMDeviceWifi *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_WIFI (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_WIFI_GET_PRIVATE (device)->hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_WIFI_GET_PRIVATE (device)->hw_address);
 }
 
 /**
@@ -109,7 +109,7 @@ nm_device_wifi_get_permanent_hw_address (NMDeviceWifi *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE_WIFI (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_WIFI_GET_PRIVATE (device)->perm_hw_address);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_WIFI_GET_PRIVATE (device)->perm_hw_address);
 }
 
 /**
diff --git a/libnm/nm-device-wpan.c b/libnm/nm-device-wpan.c
index 24d16faf13..3dfa8f267c 100644
--- a/libnm/nm-device-wpan.c
+++ b/libnm/nm-device-wpan.c
@@ -50,7 +50,7 @@ nm_device_wpan_get_hw_address (NMDeviceWpan *device)
 {
         g_return_val_if_fail (NM_IS_DEVICE_WPAN (device), NULL);
 
-        return nm_str_not_empty (NM_DEVICE_WPAN_GET_PRIVATE (device)->hw_address);
+        return _nml_coerce_property_str_not_empty (NM_DEVICE_WPAN_GET_PRIVATE (device)->hw_address);
 }
 
 static gboolean
diff --git a/libnm/nm-device.c b/libnm/nm-device.c
index 51139bfceb..96698967b9 100644
--- a/libnm/nm-device.c
+++ b/libnm/nm-device.c
@@ -860,7 +860,7 @@ nm_device_get_iface (NMDevice *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->iface);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->iface);
 }
 
 /**
@@ -878,7 +878,7 @@ nm_device_get_ip_iface (NMDevice *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->ip_iface);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->ip_iface);
 }
 
 /**
@@ -912,7 +912,7 @@ nm_device_get_udi (NMDevice *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->udi);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->udi);
 }
 
 /**
@@ -929,7 +929,7 @@ nm_device_get_driver (NMDevice *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->driver);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->driver);
 }
 
 /**
@@ -946,7 +946,7 @@ nm_device_get_driver_version (NMDevice *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->driver_version);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->driver_version);
 }
 
 /**
@@ -963,7 +963,7 @@ nm_device_get_firmware_version (NMDevice *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->firmware_version);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->firmware_version);
 }
 
 /**
@@ -988,7 +988,7 @@ nm_device_get_type_description (NMDevice *device)
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
 	if (priv->type_description)
-		return nm_str_not_empty (priv->type_description);
+		return _nml_coerce_property_str_not_empty (priv->type_description);
 
 	if (NM_DEVICE_GET_CLASS (device)->get_type_description) {
 		desc = NM_DEVICE_GET_CLASS (device)->get_type_description (device);
@@ -1001,7 +1001,7 @@ nm_device_get_type_description (NMDevice *device)
 		typename += 8;
 	priv->type_description = g_ascii_strdown (typename, -1);
 
-	return nm_str_not_empty (priv->type_description);
+	return _nml_coerce_property_str_not_empty (priv->type_description);
 }
 
 /**
@@ -1861,7 +1861,7 @@ nm_device_get_physical_port_id (NMDevice *device)
 {
 	g_return_val_if_fail (NM_IS_DEVICE (device), NULL);
 
-	return nm_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->physical_port_id);
+	return _nml_coerce_property_str_not_empty (NM_DEVICE_GET_PRIVATE (device)->physical_port_id);
 }
 
 /**
diff --git a/libnm/nm-ip-config.c b/libnm/nm-ip-config.c
index bc313bb327..19e008ed05 100644
--- a/libnm/nm-ip-config.c
+++ b/libnm/nm-ip-config.c
@@ -377,7 +377,7 @@ nm_ip_config_get_gateway (NMIPConfig *config)
 {
 	g_return_val_if_fail (NM_IS_IP_CONFIG (config), NULL);
 
-	return nm_str_not_empty (NM_IP_CONFIG_GET_PRIVATE (config)->gateway);
+	return _nml_coerce_property_str_not_empty (NM_IP_CONFIG_GET_PRIVATE (config)->gateway);
 }
 
 /**
diff --git a/libnm/nm-libnm-utils.h b/libnm/nm-libnm-utils.h
index 2e0c792aba..39b86aac64 100644
--- a/libnm/nm-libnm-utils.h
+++ b/libnm/nm-libnm-utils.h
@@ -7,6 +7,7 @@
 #define __NM_LIBNM_UTILS_H__
 
 #include "nm-types.h"
+#include "nm-glib-aux/nm-ref-string.h"
 
 /*****************************************************************************/
 
@@ -106,6 +107,36 @@ void _nml_dbus_log (NMLDBusLogLevel level,
 
 /*****************************************************************************/
 
+static inline const char *
+_nml_coerce_property_str_not_null (const char *str)
+{
+	return str ?: "";
+}
+
+static inline const char *
+_nml_coerce_property_str_not_empty (const char *str)
+{
+	return str && str[0] ? str : NULL;
+}
+
+static inline const char *
+_nml_coerce_property_object_path (NMRefString *path)
+{
+	if (!path)
+		return NULL;
+	if (nm_streq (path->str, "/"))
+		return NULL;
+	return path->str;
+}
+
+static inline const char *const*
+_nml_coerce_property_strv_not_null (char **strv)
+{
+	return ((const char *const*) strv) ?: NM_PTRARRAY_EMPTY (const char *);
+}
+
+/*****************************************************************************/
+
 char *nm_utils_wincaps_to_dash (const char *caps);
 
 /*****************************************************************************/
diff --git a/libnm/nm-manager.c b/libnm/nm-manager.c
index 10fb4a18b6..872c9fa8b9 100644
--- a/libnm/nm-manager.c
+++ b/libnm/nm-manager.c
@@ -436,7 +436,7 @@ nm_manager_get_version (NMManager *manager)
 {
 	g_return_val_if_fail (NM_IS_MANAGER (manager), NULL);
 
-	return nm_str_not_empty (NM_MANAGER_GET_PRIVATE (manager)->version);
+	return _nml_coerce_property_str_not_empty (NM_MANAGER_GET_PRIVATE (manager)->version);
 }
 
 NMState
diff --git a/libnm/nm-vpn-connection.c b/libnm/nm-vpn-connection.c
index 3927397e31..a0d673e913 100644
--- a/libnm/nm-vpn-connection.c
+++ b/libnm/nm-vpn-connection.c
@@ -67,7 +67,7 @@ nm_vpn_connection_get_banner (NMVpnConnection *vpn)
 {
 	g_return_val_if_fail (NM_IS_VPN_CONNECTION (vpn), NULL);
 
-	return nm_str_not_empty (NM_VPN_CONNECTION_GET_PRIVATE (vpn)->banner);
+	return _nml_coerce_property_str_not_empty (NM_VPN_CONNECTION_GET_PRIVATE (vpn)->banner);
 }
 
 /**