How do I timeout a recv() function in c++?

I have a program running on a server communicating with another program running on the client. They both sen开发者_开发知识库d data and files back and forth.

I notice that whenever there is a socHandler.read() (function to read data coming in on socket), it gets stuck waiting for data to arrive.

This is what the function looks like.

int CSocHandler::read(char * inBuffer, INT64 iBytesToRead){

    bool blReadMore=false;
    int retVal = 0;

    int iOutputPointer = 0;


    do{
        blReadMore = false;
        if (iStartOfBuffer == iEndOfBuffer) {   //Buffer empty
            if (blClosed ) {
                return -1;
            }
            iStartOfBuffer = 0;
            iEndOfBuffer = 0;
            size_t bufferRemaining = BUFFER_SIZE-iEndOfBuffer;
                        int bytesRecvd = recv( sock, &buffer[iEndOfBuffer], (int)iBytesToRead<bufferRemaining?iBytesToRead:bufferRemaining), 0 );   
            if ( bytesRecvd <= 0) {
                close();
                Yield();
                return retVal;
            }
        }
    } while(blReadMore);

    return retVal;
  }

The variable sock is a type SOCKET and is a global variable defined elsewhere. How can I set the options or make this recv() call non-blocking only for this function call and no affect any other function?

I believe this is where it gets stuck waiting for data, and I want to make it timeout after X seconds.

---

Call select() to query if the socket has any pending data before then calling recv() to read it.

---

Use select(2) on the socket before the recv.

Using Perl syntax, it would look like

sub read_with_timeout {
   my ($sock, $bytes_to_read, $timeout) = @_;

   my $sel = IO::Select->new($sock);
   my $end_time = Time::HiRes::time() + $timeout;

   my $buf = '';
   while ($bytes_to_read) {
      $timeout >= 0 && () = $sel->can_read($timeout);
         or die("Timeout");

      my $rv = sysread($sock, $buf, $bytes_to_read, length($buf));
      die "read: $!" if !defined($rv);
      die "Premature eof" if !$rv;

      $bytes_to_read -= $rv;

      $timeout = $end_time - Time::HiRes::time();
   }

   return $buf;
}

can_read is a call to select(2).