platform: add nm_linux_platform_lookup()

Give a direct access to the cache to lookup values there. This is only
useful for testing.

src/platform/nm-linux-platform.c

@@ -3728,6 +3728,16 @@ cache_lookup_link (NMPlatform *platform, int ifindex)
 	return obj_cache;
 }
 
+const NMPlatformObject *const*
+nm_linux_platform_lookup (NMPlatform *platform, const NMPCacheId *cache_id, guint *out_len)
+{
+	g_return_val_if_fail (NM_IS_LINUX_PLATFORM (platform), NULL);
+	g_return_val_if_fail (cache_id, NULL);
+
+	return nmp_cache_lookup_multi (NM_LINUX_PLATFORM_GET_PRIVATE (platform)->cache,
+	                               cache_id, out_len);
+}
+
 static GArray *
 link_get_all (NMPlatform *platform)
 {

src/platform/nm-linux-platform.h

@@ -52,4 +52,10 @@ NMPlatform *nm_linux_platform_new (gboolean netns_support);
 
 void nm_linux_platform_setup (void);
 
+struct _NMPCacheId;
+
+const NMPlatformObject *const *nm_linux_platform_lookup (NMPlatform *platform,
+                                                         const struct _NMPCacheId *cache_id,
+                                                         guint *out_len);
+
 #endif /* __NETWORKMANAGER_LINUX_PLATFORM_H__ */

src/platform/nmp-object.h

@@ -95,8 +95,9 @@ typedef enum { /*< skip >*/
 } NMPCacheIdType;
 
 typedef struct _NMPObject NMPObject;
+typedef struct _NMPCacheId NMPCacheId;
 
-typedef struct {
+struct _NMPCacheId {
 	union {
 		NMMultiIndexId base;
 		guint8 _id_type; /* NMPCacheIdType as guint8 */
@@ -136,7 +137,7 @@ typedef struct {
 			struct in6_addr _misaligned_network;
 		} routes_by_destination_ip6;
 	};
-} NMPCacheId;
+};
 
 extern NMPCacheId _nmp_cache_id_static;
 #define NMP_CACHE_ID_STATIC  (&_nmp_cache_id_static)