This example handles the client side of a pipe. It attempts to open an existing named pipe, if the pipe is not available, it uses this API to wait until it becames avalilable and opens it. It then sets the pipe handle state, sends a message to the host, reads the host reply, and finally closes the pipe.

Before running this example, compile and run the example code shown in the DosConnectNPipe, DosCreateNPipe, DosDisConnectNPipe, or DosSetNPipeSem functions, which handles the host side of the pipe.

#define INCL_DOSFILEMGR       /* DOS File Manager values */
#define INCL_DOSNMPIPES       /* DOS Named Pipes values */
#define INCL_DOSSEMAPHORES    /* DOS Semaphore values */
#define INCL_DOSERRORS        /* DOS Error values */
#include <os2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(VOID) {
   APIRET   rc                     = NO_ERROR;   /* Return code */
   CHAR     message[256]           = "";         /* Message buffer */
   HFILE    PipeHandle             = NULLHANDLE; /* Pipe handle */
   struct   _AVAILDATA  BytesAvail = {0};
   UCHAR    Buffer[200]            = {0};
   ULONG    bytes                  = 0;
   ULONG    Action                 = 0;
   ULONG    PipeState              = 0;
   ULONG    HandType               = 0;
   ULONG    FlagWord               = 0;
   ULONG    BytesRead              = 0;

   rc = DosOpen("\\PIPE\\EXAMPLE", &PipeHandle, &Action, 0, 0, FILE_OPEN,
                OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYREADWRITE |
                OPEN_FLAGS_FAIL_ON_ERROR, NULL);
   if (rc == ERROR_PIPE_BUSY)
      if (DosWaitNPipe("\\PIPE\\EXAMPLE", 30000)) {
         rc = DosOpen("\\PIPE\\EXAMPLE", &PipeHandle, &Action, 0, 0, FILE_OPEN,
                      OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYREADWRITE |
                      OPEN_FLAGS_FAIL_ON_ERROR, NULL);
      }

   if (rc != NO_ERROR) {
      printf("DosOpen error: error code = %u\n", rc);
      return 1;
   }  else printf("Connected to HOST\n");

   rc = DosSetNPHState(PipeHandle, NP_WAIT);
   if (rc != NO_ERROR) {
      printf("DosSetNPHState error: error code = %u\n", rc);
      return 1;
   }

   printf("Enter message to send to PIPEHOST: ");

   fflush(NULL);  /* Cause above printf to show on display */
   gets(message);

   rc = DosWrite(PipeHandle, message, strlen(message), &bytes);
   if (rc != NO_ERROR) {
      printf("DosWrite error: error code = %u\n", rc);
      return 1;
   }
   rc = DosRead(PipeHandle, message, sizeof(message), &bytes);
   if (rc != NO_ERROR) {
      printf("DosRead error: error code = %u\n", rc);
      return 1;
   }

   printf("\nMessage received from PIPEHOST was: %s\n\n", message);

   rc = DosClose(PipeHandle);
   printf("...Disconnected\n");
   return NO_ERROR;
}