Thread: NAMED PIPE - 1 record behind

I have one server, and multiple clients running as seperate tasks, NOT children. When a client initially writes to the named pipe, the server does a line feed. I have no idea where this comes from. It does a line feed, but does not display the buffer. After that, for every client write to the server, the server shows the previous record. In other words, I never see the first write until a second write occurs, and then the server display is always one record behind. I don't understand why the first write stays in the pipe until a second write occurs. Obviously, I need the first write to display when I perform the first write.

Code:

 /*************************************
*     Server     Server     Server     Server         *
*     server_test_1                                          *
 *************************************/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>
char *ServerPipe="/tmp/Server.pipe";
int main(int argc, char *argv[])
{
     int     Server;
     int     BytesIn;
     char  Buffer[200] = {0};
     int    BufferSize = sizeof(Buffer);

     if (access(ServerPipe, F_OK) != 0) {

          if (mkfifo(ServerPipe, S_IRWXU) != 0) {
 
               printf("\n\nCan't create the FIFO\n\n");
               return(10);
          }
     }
     printf("\n\nServer - Waiting for Client to press Q\n\n");
     Server = open(ServerPipe, O_RDONLY);
     do {

          BytesIn=read(Server, Buffer, BufferSize);
          printf("\nBytesIn: %d %d - %s", BytesIn,
                                                          strlen(Buffer),
                                                          Buffer);
          Buffer[1] = '\0';
 
     } while (Buffer[0] != 'Q');
     sleep(1);
     close(Server);
     unlink(ServerPipe);
     printf("\n\nTat's all folken....\n\n");
     return(0);
}

 /***************************************
*     Client     Client     Client     Client     Client     *
*                                                                       *
*     client_test_2                                               *
 ***************************************/
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <termios.h>
char *ServerPipe="/tmp/Server.pipe";

int main(int argc, char *argv[])
{

     int Server, x = 0;
     char Buffer[200] = {0};
     int  BytesOut;

     printf("\n\nClient_Test_1\n\n");
     if (access(ServerPipe, F_OK) != 0) {

          printf("\n\nServer not running!!!!\n\n");
          return(10);
     }
     Server=open(ServerPipe, O_WRONLY);
     do {

          printf("\nPress 'Q' to quit, 'S' to send...");
          Buffer[0] = getchar();
          if (Buffer[0] == 'S') {

               sprintf(Buffer, "Test record %d from PID: %d", ++x,
                                                                                    getpid());
               printf("\nSending...");
               BytesOut = write(Server, Buffer, sizeof(Buffer));
               printf("BytesOut: %d", BytesOut);
         }
     }
     while (Buffer[0] != 'Q');
     Buffer[1] = '\0';
     write(Server, Buffer, strlen(Buffer));
     close(Server);
     printf("\n\nThat's all folks....\n\n");
     return(0);
}

The problem is, that the outputstream is also buffered.
You can call 'fflush(stdout)' after the printf, or you send an '\n' after the string like:

Code:

printf("BytesIn: %d %d - %s\n", BytesIn, strlen(Buffer), Buffer);

thank you/n thank you/n thank you/n This was so weird. I was getting all the data, just not as I "expected"... sometimes you have to stand back and get away from it for a bit, and get some assistance from the guru's that are way beyond my abilities. The important thing .... never, ever, ever, give up/n/n/n

I can not thank you enough. I now can get some sleep and start thinking about sockets.......CR/LF/FLUSH/FLUSH/FLUSH