Wrap lyd_meta_is_internal to check if meta is internal

There are some internal meta attributes that libyang uses for internal
stuff and they are ignored when printing the meta collections. One (and
now also the only) example of such node is yang:lyds_tree attribute.

It can be useful to check if the meta attribute is internal. For
instance, when we want to be sure that our parsed data did not contain
any meta attributes from user. However, sometimes, libyang silently
inserts these internal attributes while parsing.

We asked upstream if there could be a function that checks for us if the
attribute is internal and therefore we should ignore it. They kindly
provided us with such function (`lyd_meta_is_internal`) [1].

This commit wraps the function. Unfortunately, our Meta class does not
wrap lyd_meta, only copies data from the structure so we can't just call
this function when requested but we call it in Meta object construction
which creates a little overhead in both time and memory.

[1] CESNET/libyang@f77ca9c

Change-Id: Id772ded765569089525cf4fd5dba8a64efe87d02

CMakeLists.txt

@@ -28,7 +28,7 @@ option(WITH_DOCS "Create and install internal documentation (needs Doxygen)" ${D
 option(BUILD_SHARED_LIBS "By default, shared libs are enabled. Turn off for a static build." ON)
 
 find_package(PkgConfig REQUIRED)
-pkg_check_modules(LIBYANG REQUIRED libyang>=3.0.1 IMPORTED_TARGET)
+pkg_check_modules(LIBYANG REQUIRED libyang>=3.0.11 IMPORTED_TARGET)
 set(LIBYANG_CPP_PKG_VERSION "2")
 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)

include/libyang-cpp/DataNode.hpp

@@ -183,6 +183,7 @@ class LIBYANG_CPP_EXPORT Meta {
     std::string name() const;
     std::string valueStr() const;
     Module module() const;
+    bool isInternal() const;
 
 private:
     friend Iterator<Meta, IterationType::Meta>;
@@ -191,6 +192,7 @@ class LIBYANG_CPP_EXPORT Meta {
     std::string m_name;
     std::string m_value;
     Module m_mod;
+    bool m_isInternal;
 };
 
 

src/DataNode.cpp

@@ -981,6 +981,7 @@ Meta::Meta(lyd_meta* meta, std::shared_ptr<ly_ctx> ctx)
     : m_name(meta->name)
     , m_value(lyd_get_meta_value(meta))
     , m_mod(meta->annotation->module, ctx)
+    , m_isInternal(lyd_meta_is_internal(meta))
 {
 }
 
@@ -999,6 +1000,12 @@ Module Meta::module() const
     return m_mod;
 }
 
+/** @brief Checks if the meta attribute is considered internal for libyang, see `lyd_meta_is_internal` */
+bool Meta::isInternal() const
+{
+    return m_isInternal;
+}
+
 /**
  * Creates a JSON attribute for an opaque data node.
  * Wraps `lyd_new_attr`.

tests/data_node.cpp

@@ -1899,6 +1899,7 @@ TEST_CASE("Data Node manipulation")
             }
 
             auto meta = netconfDeletePresenceCont.meta();
+            REQUIRE(std::none_of(meta.begin(), meta.end(), [](const auto& meta) { return meta.isInternal(); }));
             std::transform(meta.begin(), meta.end(), std::back_inserter(actual), [] (const auto& it) { return std::pair{it.name(), it.valueStr()}; });
             REQUIRE(actual == expected);
         }
@@ -1976,6 +1977,28 @@ TEST_CASE("Data Node manipulation")
             REQUIRE(*out->printStr(libyang::DataFormat::JSON, libyang::PrintFlags::WithSiblings) == expectedJson);
             REQUIRE(*out->printStr(libyang::DataFormat::XML, libyang::PrintFlags::WithSiblings) == expectedXml);
         }
+
+        DOCTEST_SUBCASE("libyang internal metadata")
+        {
+            /*
+             * - currently, libyang creates an internal meta node yang:lyds_tree representing a RB-tree for ordering of data in lists
+             * - this test depends on internal libyang implementation which can of course change anytime
+             * - but it seems that yang:lyds_tree can't be created manually (there is no valid value for it?) and I don't know how to test this otherwise
+             */
+            DOCTEST_SUBCASE("leaf-list ordered by system")
+            {
+                auto node = ctx.parseData(R"({"example-schema3:valuesOrderedBySystem": [1,2,3]})"s, libyang::DataFormat::JSON, libyang::ParseOptions::Strict | libyang::ParseOptions::NoState | libyang::ParseOptions::ParseOnly);
+                const auto metaColl = node->meta();
+                REQUIRE(std::find_if(metaColl.begin(), metaColl.end(), [](const auto& meta) { return meta.isInternal(); }) != metaColl.end());
+            }
+
+            DOCTEST_SUBCASE("leaf-list ordered by user")
+            {
+                auto node = ctx.parseData(R"({"example-schema3:values": [1,2,3]})"s, libyang::DataFormat::JSON, libyang::ParseOptions::Strict | libyang::ParseOptions::NoState | libyang::ParseOptions::ParseOnly);
+                const auto metaColl = node->meta();
+                REQUIRE(std::find_if(metaColl.begin(), metaColl.end(), [](const auto& meta) { return meta.isInternal(); }) == metaColl.end());
+            }
+        }
     }
 
     DOCTEST_SUBCASE("Extension nodes")

tests/example_schema.hpp

@@ -293,6 +293,10 @@ module example-schema3 {
         type int32;
     }
 
+    leaf-list valuesOrderedBySystem {
+        type int32;
+    }
+
     list person {
         key 'name';
         leaf name {