/*-------------------------------------------------------------------*/
/* testpipe.c                                                        */
/* The pipe system call.                                             */
/*-------------------------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <wait.h>

#define BUFFER_SIZE 100

int main(int argc, char *argv[])
{
   int piPipeFd[2];
   int iProducerPid;
   int iConsumerPid;
   int iRet;

   iRet = pipe(piPipeFd);
   if (iRet == -1) {perror(argv[0]); return 1; }

   fflush(NULL);
   iProducerPid = fork();  /* Fork a producer child. */
   if (iProducerPid == -1) {perror(argv[0]); return 1; }

   if (iProducerPid == 0)
   {
      /* Producer child */

      char pcBuffer[] = "somedata\n";
      int iBytesWritten = 0;

      iRet = close(piPipeFd[0]);
      if (iRet == -1) {perror(argv[0]); exit(1); }

      while (iBytesWritten < 9)
      {
         iRet = write(piPipeFd[1], pcBuffer + iBytesWritten, 9 - iBytesWritten);
         if (iRet == -1) {perror(argv[0]); exit(1); }
         iBytesWritten += iRet;
      }

      iRet = close(piPipeFd[1]);
      if (iRet == -1) {perror(argv[0]); exit(1); }

      exit(0);
   }

   iRet = close(piPipeFd[1]);
   if (iRet == -1) {wait(NULL); perror(argv[0]); return 1; }

   fflush(NULL);
   iConsumerPid = fork();  /* Fork a consumer child. */
   if (iConsumerPid == -1) {wait(NULL); perror(argv[0]); return 1; }

   if (iConsumerPid == 0)
   {
      /* Consumer child */

      char pcBuffer[BUFFER_SIZE];
      int iBytesRead = 0;
      int i;

      while (iBytesRead < 9)
      {
         iRet = read(piPipeFd[0], pcBuffer + iBytesRead, 9 - iBytesRead);
         if (iRet == -1) {perror(argv[0]); exit(1); }
         iBytesRead += iRet;
      }

      iRet = close(piPipeFd[0]);
      if (iRet == -1) {perror(argv[0]); exit(1); }

      /* Print the data to make sure it was communicated properly. */
      for (i = 0; i < 9; i++)
         putchar(pcBuffer[i]);

      exit(0);
   }

   iRet = close(piPipeFd[0]);
   if (iRet == -1) {wait(NULL); wait(NULL); perror(argv[0]); return 1; }

   wait(NULL);
   wait(NULL);

   return 0;
}

/* Sample execution:

$ gcc -Wall -ansi -pedantic -o testpipe testpipe.c
$ testpipe
somedata
$

*/