Handle null json EVM ASM input

Author: r0qs

libevmasm/Assembly.cpp

@@ -510,6 +510,10 @@ Json::Value Assembly::assemblyJSON(std::map<std::string, unsigned> const& _sourc
 
 std::pair<std::shared_ptr<Assembly>, std::vector<std::string>> Assembly::fromJSON(Json::Value const& _json, std::vector<std::string> const& _sourceList, int _level)
 {
+	std::shared_ptr<Assembly> result = std::make_shared<Assembly>(langutil::EVMVersion(), _level == 0, "");
+	if (_json.isNull())
+		return std::make_pair(result, std::vector<std::string>());
+
 	solRequire(_json.isObject(), AssemblyImportException, "Supplied JSON is not an object.");
 	static std::set<std::string> const validMembers{".code", ".data", ".auxdata", "sourceList"};
 	for (auto const& attribute: _json.getMemberNames())
@@ -534,7 +538,6 @@ std::pair<std::shared_ptr<Assembly>, std::vector<std::string>> Assembly::fromJSO
 			"Member 'sourceList' is only allowed in root JSON object."
 		);
 
-	std::shared_ptr<Assembly> result = std::make_shared<Assembly>(langutil::EVMVersion(), _level == 0, "");
 	std::vector<std::string> sourceList;
 	if (_json.isMember("sourceList"))
 	{

libevmasm/EVMAssemblyStack.cpp

@@ -36,7 +36,7 @@ void EVMAssemblyStack::parseAndAnalyze(std::string const& _sourceName, std::stri
 	solAssert(!m_evmAssembly);
 	m_name = _sourceName;
 	Json::Value assemblyJson;
-	solRequire(jsonParseStrict(_source, assemblyJson), AssemblyImportException, "Could not parse JSON file.");
+	solRequire(jsonParse(_source, assemblyJson), AssemblyImportException, "Could not parse JSON file.");
 	std::tie(m_evmAssembly, m_sourceList) = evmasm::Assembly::fromJSON(assemblyJson);
 	solRequire(m_evmAssembly != nullptr, AssemblyImportException, "Could not create evm assembly object.");
 }

libsolutil/JSON.cpp

@@ -144,6 +144,12 @@ bool jsonParseStrict(std::string const& _input, Json::Value& _json, std::string*
 	return parse(readerBuilder, _input, _json, _errs);
 }
 
+bool jsonParse(std::string const& _input, Json::Value& _json, std::string* _errs /* = nullptr */)
+{
+	static Json::CharReaderBuilder readerBuilder;
+	return parse(readerBuilder, _input, _json, _errs);
+}
+
 std::optional<Json::Value> jsonValueByPath(Json::Value const& _node, std::string_view _jsonPath)
 {
 	if (!_node.isObject() || _jsonPath.empty())

libsolutil/JSON.h

@@ -69,6 +69,8 @@ std::string jsonPrint(Json::Value const& _input, JsonFormat const& _format);
 /// \return \c true if the document was successfully parsed, \c false if an error occurred.
 bool jsonParseStrict(std::string const& _input, Json::Value& _json, std::string* _errs = nullptr);
 
+bool jsonParse(std::string const& _input, Json::Value& _json, std::string* _errs = nullptr);
+
 /// Retrieves the value specified by @p _jsonPath by from a series of nested JSON dictionaries.
 /// @param _jsonPath A dot-separated series of dictionary keys.
 /// @param _node The node representing the start of the path.

scripts/ASTImportTest.sh

@@ -207,11 +207,6 @@ function test_evmjson_import_export_equivalence
     local export_options=(--bin --asm-json "${input_files[@]}" --output-dir export/)
     run_solc "${export_options[@]}"
 
-    # NOTE: If there is no bytecode, the compiler produces a JSON file that contains just 'null'.
-    # This is not accepted by assembly import though so we must skip such contracts.
-    echo -n null > null
-    find export/ -name '*.json' -exec cmp --quiet --bytes=4 {} null \; -delete
-
     find export/ -name '*.bin' -size 0 -delete
 
     for asm_json_file in export/*.json