Question : Sockets - Non-blocking read

Hi,

    I tried with the following code to implelemt a non-blocking read from sockets. But this returns error while reading.

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

int main()
{
    int ctrlsock,datasock;
      struct sockaddr_in sock;
      char command[100];
      int iores,bytesread;
      fd_set sockset;
      struct timeval tv;
      int valopts;
      socklen_t slen;


      if((ctrlsock=socket(AF_INET,SOCK_STREAM,0))<0)
      {
            printf("Error Creating Socket\n");
            return 0;
      }
      if(fcntl(ctrlsock,F_SETFL,fcntl(ctrlsock,F_GETFL) | O_NONBLOCK)<0)
      {
            printf("Error switching to non-blocking mode\n");
            return 0;
      }


      sock.sin_family=AF_INET;
      sock.sin_port=htons(21);
      if(inet_aton("10.2.0.111",(struct in_addr*)&sock.sin_addr)<=0)
      {
            printf("Invalid IP address\n");
            return 0;
      }
      if(connect(ctrlsock,(struct sockaddr*)&sock,sizeof(sock))<0)
      {
            printf("Error connecing to server\n");
            if(errno==EINPROGRESS)
            {
                  printf("EINPROGRESS...\n");
                  tv.tv_sec=150;
                  tv.tv_usec=0;
                  FD_ZERO(&sockset);
                  FD_SET(ctrlsock,&sockset);
                  if(select(ctrlsock+1,&sockset,&sockset,NULL,&tv)<=0)
                  {
                        printf("Damn... Cannot open non-blocking socket!\n");
                        return (0);
                  }
                  slen=sizeof(int);
                  if(getsockopt(ctrlsock,SOL_SOCKET,SO_ERROR,&valopts,&slen)!=0)
                  {
                        printf("Error with getsockopt\n");
                        return 0;
                  }
            }
      }
      printf("Connected to Server.\n");
      printf("Reading from server...\n");
      
      do
      {
            iores=read(ctrlsock,command,99);
            if(iores<0)
            {
                  printf("Error reading from server\n");
                  break;
            }
            command[iores]='\0';
            printf("%s",command);
            printf("iores:%d\n",iores);
            
      }while(iores>=0);
      printf("\n");
      close(ctrlsock);
      
      
      return 0;

}

I even tried with ioctl - FIONBIO. But that does'nt help. Can anyone tell what's wrong with the code?

Answer : Sockets - Non-blocking read

from the read man page

     EAGAIN Non-blocking I/O has been selected using O_NONBLOCK and no data was immediately available for reading.