#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <limits.h>
#include <fcntl.h>


static int bailout(const char *str)
{
  perror(str);
  exit(EXIT_FAILURE);
}


static void do_child(int rd)
{
  char buf[16384];
  struct timespec ts = {2, 0};
  int in = 0;
  !nanosleep(&ts, NULL) || bailout("child: nanosleep");
  while (1) {
    ssize_t rdcnt = read(rd, buf, sizeof buf);
    if (-1 == rdcnt)
      bailout("child: read");
    if (0 == rdcnt)
      break;
    in += rdcnt;
  }
  fprintf(stderr, "in = %d\n", in);
  exit(EXIT_SUCCESS);
}


static void do_parent(int wd)
{
  int out;
  char buf[5*PIPE_BUF];
  FILE *stream;
  int opts;
  
  memset(buf, 'a', sizeof buf -1);
  buf[sizeof buf -1] = 0;
  
  if (-1 == (opts = fcntl(wd, F_GETFL))
      || -1 == fcntl(wd, F_SETFL, opts | O_NONBLOCK))
    bailout("parent: fcntl");
  
  NULL != (stream = fdopen(wd, "w")) || bailout("parent: fdopen");
  !setvbuf(stream, NULL, _IONBF, 0) || bailout("parent: setvbbuf");
  out = fprintf(stream, "%s", buf);
  fprintf(stderr, "out = %d (%s)\n", out, strerror(errno));
  exit(EXIT_SUCCESS);
}


void main(void)
{
  int pipe_ends[2];
  
  !pipe(pipe_ends) || bailout("pipe");
  switch (fork()) {
    case -1:
      bailout("fork");
    case 0:
      close(pipe_ends[1]);
      do_child(pipe_ends[0]);
    default:
      close(pipe_ends[0]);
      do_parent(pipe_ends[1]);
  }
}