This example handles the client side of a pipe. It opens an existing named pipe and event semaphore, sends a message to the host, displays the state of the pipe semaphore, reads the host reply, and finally closes the event semaphore and 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 */
   HEV      hev                    = NULLHANDLE; /* Event semaphore handle */
   PIPEINFO PipeBuffer[4]          = {{0}};
   struct   _AVAILDATA  BytesAvail = {0};
   UCHAR    Buffer[200]            = {0};
   ULONG    bytes                  = 0;
   ULONG    Action                 = 0;
   int      i                      = 0;
   PIPESEMSTATE infobuf[3]         = {{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 != NO_ERROR) {
      printf("DosOpen error: error code = %u\n", rc);
      return 1;
   }  else printf("Connected to Pipe.\n");

   rc = DosOpenEventSem("\\SEM32\\PIPE\\EXAMPLE", &hev);
   if (rc != NO_ERROR) {
      printf("DosOpenEventSem error: error code = %u\n", rc);
      return 1;
   }

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

   fflush(NULL);  /* Flush printf buffer */
   gets(message);

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

   rc = DosQueryNPipeSemState((HSEM) hev, infobuf, sizeof(PIPESEMSTATE)*3);
   if (rc != NO_ERROR) {
     printf("DosQueryNPipeSemState error: return code = %u\n",rc);
     return 1;
   }

   printf("Status  Flag   Key   Avail\n------ ------ ------ ------\n");
   for (i=0; i<3; i++)
     printf("%6u %6u %6u %6u\n", infobuf[i].fStatus,
            infobuf[i].fFlag, infobuf[i].usKey, infobuf[i].usAvail);

   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: %s\n\n", message);

   rc = DosCloseEventSem(hev);
   /* Should check if (rc != NO_ERROR) here... */

   rc = DosClose(PipeHandle);
   /* Should check if (rc != NO_ERROR) here... */

   printf("...Disconnected\n");
   return NO_ERROR;
}