Ensure FlatFileSchemaResolver enforces relative references (#1425)

Signed-off-by: Juan Cruz Viotti <[email protected]>

src/jsonschema/include/sourcemeta/jsontoolkit/jsonschema_resolver.h

@@ -145,6 +145,7 @@ class SOURCEMETA_JSONTOOLKIT_JSONSCHEMA_EXPORT FlatFileSchemaResolver {
   struct Entry {
     std::filesystem::path path;
     std::optional<std::string> default_dialect;
+    std::string original_identifier;
   };
 
 private:

src/jsonschema/resolver.cc

@@ -95,8 +95,9 @@ auto FlatFileSchemaResolver::add(
     throw SchemaError(error.str());
   }
 
-  const auto result{this->schemas.emplace(identifier.value(),
-                                          Entry{canonical, default_dialect})};
+  const auto result{this->schemas.emplace(
+      identifier.value(),
+      Entry{canonical, default_dialect, identifier.value()})};
   if (!result.second && result.first->second.path != canonical) {
     std::ostringstream error;
     error << "Cannot register the same identifier twice: "
@@ -128,6 +129,14 @@ auto FlatFileSchemaResolver::operator()(std::string_view identifier) const
       schema.assign("$schema", JSON{result->second.default_dialect.value()});
     }
 
+    sourcemeta::jsontoolkit::reidentify(schema,
+                                        result->second.original_identifier,
+                                        *this, result->second.default_dialect);
+    // Because we allow re-identification, we can get into issues unless we
+    // always try to relativize references
+    sourcemeta::jsontoolkit::relativize(schema, default_schema_walker, *this,
+                                        result->second.default_dialect,
+                                        result->second.original_identifier);
     sourcemeta::jsontoolkit::reidentify(schema, result->first, *this,
                                         result->second.default_dialect);
 

test/jsonschema/jsonschema_flat_file_resolver_test.cc

@@ -196,3 +196,24 @@ TEST(JSONSchema_FlatFileSchemaResolver, reidentify) {
 
   EXPECT_EQ(resolver("https://example.com").value(), expected);
 }
+
+TEST(JSONSchema_FlatFileSchemaResolver, with_absolute_references) {
+  sourcemeta::jsontoolkit::FlatFileSchemaResolver resolver;
+  const auto schema_path{std::filesystem::path{SCHEMAS_PATH} /
+                         "2020-12-absolute-ref.json"};
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$id": "https://www.sourcemeta.com/2020-12-absolute-ref.json",
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "$ref": "2020-12-id.json"
+  })JSON");
+
+  const auto &identifier{resolver.add(schema_path)};
+  EXPECT_EQ(identifier, "https://www.sourcemeta.com/2020-12-absolute-ref.json");
+  EXPECT_TRUE(resolver("https://www.sourcemeta.com/2020-12-absolute-ref.json")
+                  .has_value());
+  EXPECT_EQ(
+      resolver("https://www.sourcemeta.com/2020-12-absolute-ref.json").value(),
+      expected);
+}

test/jsonschema/schemas/2020-12-absolute-ref.json

@@ -0,0 +1,5 @@
+{
+  "$id": "https://www.sourcemeta.com/2020-12-absolute-ref.json",
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "https://www.sourcemeta.com/2020-12-id.json"
+}