#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#define FIFOT_NAME  "fifot.fifo"

int
main(int argc, char *argv[])
{
   int         readfd,
               val,
               writefd;
   struct stat stat_buf;

   if (stat(FIFOT_NAME, &stat_buf) == -1)
   {
      if (errno == ENOENT)
      {
         if (mkfifo(FIFOT_NAME, S_IRUSR | S_IWUSR) == -1)
         {
            (void)fprintf(stderr, "mkfifo() error : %s\n", strerror(errno));
            exit(1);
         }
      }
      else
      {
         (void)fprintf(stderr, "stat() error : %s\n", strerror(errno));
         exit(1);
      }
   }

   if ((readfd = open(FIFOT_NAME, O_RDONLY | O_NONBLOCK)) == -1)
   {
      (void)fprintf(stderr, "open() error : %s\n", strerror(errno));
      exit(1);
   }
   if ((writefd = open(FIFOT_NAME, O_WRONLY)) == -1)
   {
      (void)fprintf(stderr, "open() error : %s\n", strerror(errno));
      exit(1);
   }
   if ((val = fcntl(readfd, F_GETFD, 0)) == -1)
   {
      (void)fprintf(stderr, "fcntl() error : %s\n", strerror(errno));
      exit(1);
   }
   val &= ~O_NONBLOCK;
   if (fcntl(readfd, F_SETFD, val) == -1)
   {
      (void)fprintf(stderr, "fcntl() error : %s\n", strerror(errno));
      exit(1);
   }
   if (argc == 1)
   {
      int    ret;
      char   buffer[13];
      fd_set rset;

      FD_ZERO(&rset);
      FD_SET(readfd, &rset);
      ret = select(readfd + 1, &rset, NULL, NULL, NULL);
      if (FD_ISSET(readfd, &rset))
      {
         if ((ret = read(readfd, &buffer, 12)) != 12)
         {
            (void)fprintf(stderr, "read() error (%d) : %s\n", ret, strerror(errno));
            exit(1);
         }
         buffer[12] = '\0';
         (void)fprintf(stdout, "Have received `%s'\n", buffer);
      }
      else
      {
         (void)fprintf(stderr, "select() error : %s\n", strerror(errno));
         exit(1);
      }
   }
   else
   {
      if (write(writefd, "Hallo Ballo!", 12) != 12)
      {
         (void)fprintf(stderr, "write() error : %s\n", strerror(errno));
         exit(1);
      }
   }
   exit(0);
}