Question

here is the situation: I need to send a data to a neighbor(socket) and then switch to listening mode. Ive got a client part in client.c, which just listens, and server part in server.c – sends data. Using sockets I need to have a main() in both of them. How should I get them “cooperate” together, so both mainss are not going result in error?

Or any other ideas how to solve this issue with sending and listening?

Thanks in advance!

Lucas

Answer 1

You can always create two executables from the sources. Each of them will have its own main.

Or, you can create a single executable and let it fork another process or create another thread. When creating a new thread you’ll specify the second “main” to be the thread function.

When fork-ing, you should create two functions main_server and main_client and let the actual main decide which of them to call, just after the fork. See snippet:

int main_server(int argc, int argv){
  //TODO: complete
  return 0;
}

int main_client(int argc, int argv){
  //TODO: complete
  return 0;
}

int main(int argc, int argv){
  //TODO: parse args and get argv_server, argv_client, argc_server, argc_client
  int pid = fork();
  if (pid < 0) {
     //TODO: handle error and leave
  } else if (pid) {
     // start client here for example
     main_client(argc_client, argv_client);
  } else {
     main_server(argc_server, argv_server);
     wait(pid);
  }
  return 0;
  /* TODO: each of the above calls should be checked for errors */
}

Hope it helps.

Note: it’s better to create a separate executable but if you are required to have only one, use the above snippet.