18 bool GetFileSize(const std::string& file_name, size_t* size) {  in GetFileSize()  argument
20   if (stat(file_name.c_str(), &stat_buf)) {  in GetFileSize()
30 unique_ptr<ostream> OpenOutputFile(const std::string& file_name,  in OpenOutputFile()  argument
32   auto* file_stream = new fstream(file_name, std::ios::out | std::ios::binary);  in OpenOutputFile()
37       message_handler->ReportMessage(Message::kStdLibError, file_name);  in OpenOutputFile()
43 unique_ptr<istream> OpenInputFile(const std::string& file_name,  in OpenInputFile()  argument
45   auto* file_stream = new fstream(file_name, std::ios::in | std::ios::binary);  in OpenInputFile()
50       message_handler->ReportMessage(Message::kStdLibError, file_name);  in OpenInputFile()
56 std::shared_ptr<DataSegment> ReadEntireFile(const std::string& file_name,  in ReadEntireFile()  argument
60   if (GetFileSize(file_name, &buffer_size)) {  in ReadEntireFile()
62         OpenInputFile(file_name, message_handler);  in ReadEntireFile()
77     message_handler->ReportMessage(Message::kStdLibError, file_name);  in ReadEntireFile()