Merge pull request #11579 from ethereum/better-errors-about-bad-paths-in-tests-with-external-sources

Better errors about bad paths in tests with external sources

libsolutil/CommonIO.cpp

@@ -43,9 +43,17 @@ namespace
 template <typename T>
 inline T readFile(std::string const& _file)
 {
+	assertThrow(boost::filesystem::exists(_file), FileNotFound, _file);
+
+	// ifstream does not always fail when the path leads to a directory. Instead it might succeed
+	// with tellg() returning a nonsensical value so that std::length_error gets raised in resize().
+	assertThrow(boost::filesystem::is_regular_file(_file), NotAFile, _file);
+
 	T ret;
 	size_t const c_elementSize = sizeof(typename T::value_type);
 	std::ifstream is(_file, std::ifstream::binary);
+
+	// Technically, this can still fail even though we checked above because FS content can change at any time.
 	assertThrow(is, FileNotFound, _file);
 
 	// get length of file:

libsolutil/CommonIO.h

@@ -33,6 +33,7 @@ namespace solidity::util
 
 /// Retrieve and returns the contents of the given file as a std::string.
 /// If the file doesn't exist, it will throw a FileNotFound exception.
+/// If the file exists but is not a regular file, it will throw NotAFile exception.
 /// If the file is empty, returns an empty string.
 std::string readFileAsString(std::string const& _file);
 

libsolutil/Exceptions.h

@@ -49,6 +49,7 @@ DEV_SIMPLE_EXCEPTION(InvalidAddress);
 DEV_SIMPLE_EXCEPTION(BadHexCharacter);
 DEV_SIMPLE_EXCEPTION(BadHexCase);
 DEV_SIMPLE_EXCEPTION(FileNotFound);
+DEV_SIMPLE_EXCEPTION(NotAFile);
 DEV_SIMPLE_EXCEPTION(DataTooLong);
 DEV_SIMPLE_EXCEPTION(StringTooLong);