simple server thread for receiving file from a local PC - file temporarily empty

Question

(I'm not a pro)

I'd like some tip on what is going wrong in my code.

The connexion is always with the same computer once the first file is received.

Just after receiving the file I want to open it to modify some variable in my main program. But the file is considered empty in the program. If I stop the program and open the file directly it contain all the data that should be there (not empty). Should I do something more when closing the output file?

modele_vao, and modele_count are variable shared with the main program (that's the reason for the mutex)

Here's the code for the thread:

    void threadservfct()
{

    while (1)
    {

        {
            boost::mutex::scoped_lock lk(m);

            std::wcout << "Server_thread START " << std::endl;
            boost::array<char, 1024> buf;
            size_t file_size = 0;
            boost::asio::io_service io_service;
            boost::asio::ip::tcp::acceptor acceptor(io_service, boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), 13));
            boost::system::error_code error;
            boost::asio::ip::tcp::socket socket(io_service);
            acceptor.accept(socket);
            boost::asio::streambuf request_buf;
            boost::asio::read_until(socket, request_buf, "\n\n");
            std::wcout << "request size:" << request_buf.size() << std::endl;
            std::istream request_stream(&request_buf);
            std::string file_path;
            request_stream >> file_path;
            request_stream >> file_size;
            request_stream.read(buf.c_array(), 2); // eat the "\n\n" 
            size_t pos = file_path.find_last_of("\\");
            if (pos != std::string::npos)
                file_path = file_path.substr(pos + 1);
            std::ofstream output_file(file_path.c_str(), std::ios_base::binary);


            if (!output_file)
            {
                std::wcout << "failed to open " << std::endl;
            }

            // write extra bytes to file
            do
            {
                request_stream.read(buf.c_array(), (std::streamsize)buf.size());
                std::wcout << __FUNCTION__ << " write " << request_stream.gcount() << " bytes" << std::endl;
                output_file.write(buf.c_array(), request_stream.gcount());
            } while (request_stream.gcount()>0);

            for (;;)
            {
                size_t len = socket.read_some(boost::asio::buffer(buf), error);
                if (len>0)
                    output_file.write(buf.c_array(), (std::streamsize)len);
                if (output_file.tellp() == (std::fstream::pos_type)(std::streamsize)file_size)
                    break; // file was received
                if (error)
                {
                    std::wcout << error << std::endl;
                    break;
                }
            }
            std::wcout << "received " << output_file.tellp() << " bytes" << std::endl;


            output_file.close();

            std::wcout << "END TRANSMISSION. Reiceived:" << file_path.c_str() << std::endl;


            std::wcout << "import new mesh" << std::endl;
            assert(load_mesh(file_path.c_str(), &modele_vao, &modele_count));
            std::wcout << "end mesh import" << std::endl;
        }

    }
}

Why C tag ? It seems to be a C++ only program. – Yann Jun 16 '14 at 11:25 — Yann, Jun 16 '14 at 11:25
yea my fault I removed it – user3544665 Jun 16 '14 at 11:28 — user3544665, Jun 16 '14 at 11:28

sehe · Answer 1 · 2014-06-16T11:53:33.180

0

You're listening on port 13. This requires administrative privileges.

Also, it's likely not what you want to do because it's a "Well known service port" http://en.wikipedia.org/wiki/Daytime_Protocol

Also, it seems very strange (to say the least) that you call threadservfct(); unconditionally in the thread. It would seem that this results in infinite recursion in the best case, and indefinite waiting in the most likely scenario.

edited Jun 16 '14 at 11:53

answered Jun 16 '14 at 11:47

sehe

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Thx for your answer. I don't know a lot about differences beetween ports. Which one should I choose then? I don't get what you mean about calling `threadservfct();` in the thread. `threadservfct();` is the thread fct -> I begin it like that `boost::thread thrd1(&threadservfct);` This thread is supposed to wait all the time for new file coming and to put the waiting part off of the main program. – user3544665 Jun 17 '14 at 06:59
@user3544665 just remove the self-call then. Here's a simple modification that was able to receive a small file correctly for me: http://paste.ubuntu.com/7656987/ And read a book :) – sehe Jun 17 '14 at 07:01
there's no self call in my fct :s you just added it but i'll look for the port 6767 plus my code works, i can receive file without problem, it's just that if I open them in the program with the `assert(load_mesh(file_path.c_str(), &modele_vao, &modele_count));` function it consider the file empty but when i close the program all the files downloaded are present with all the data – user3544665 Jun 17 '14 at 07:14
@user3544665 Oops. It appears I had a silent copy/paste error somewhere. Well, forget about the self call :) If the file exists with the data, it's obviously not empty, which means that `load_mesh` is failing for a different reason. Good luck with the rest! – sehe Jun 17 '14 at 07:36
Oh, also: http://stackoverflow.com/questions/133879/how-should-one-go-about-choosing-a-default-tcp-ip-port-for-a-new-service – sehe Jun 17 '14 at 07:37

score 0 · Accepted Answer · answered Jun 17 '14 at 09:41

0

Found the problem, the file I was opening with load_mesh was a .obj that was refering to a mtl file. The mtl file wasnt sent so that's why it didnt worked.

pretty stupid error

answered Jun 17 '14 at 09:41

user3544665

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simple server thread for receiving file from a local PC - file temporarily empty

2 Answers2