// Failed attempt to test if O_NONBLOCK was set in open

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h> // O_RDONLY
#include <errno.h>

int main(int argc, char* argv[]) {
  const int BUF_SIZE = 81;
  char buffer[BUF_SIZE];

  if (argc == 1) {
      fprintf(stderr, "Usage: %s pathname\n", argv[0]);
      exit(EXIT_FAILURE);
  }

  int fd = open(argv[1], O_RDONLY | O_NONBLOCK);
  if (fd < 0) perror("Failed to open");
  int flags = fcntl(fd, F_GETFL);
  if (flags & O_NONBLOCK == O_NONBLOCK)
  //  if ((flags & O_NONBLOCK) == O_NONBLOCK)
    puts("O_NONBLOCK was enabled in open.");
  else
    puts("O_NONBLOCK was NOT enabled in open.");
}