#include <fcntl.h>
#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

#define handle_error(msg) \
           do { perror(msg); exit(EXIT_FAILURE); } while (0)


int main(int argc, char *argv[argc+1]) {
  int fd = open(argv[1], O_RDONLY);    
  struct stat sb;
  if (fd == -1)
    handle_error("open");
  if (fstat(fd, &sb) == -1)           /* To obtain file size */
     handle_error("fstat");

  char *addr = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
  if (addr == MAP_FAILED)
    handle_error("mmap");

  printf("addr: %p\n", (void*)addr);
  printf("mmap addr: %p\n", (void*)mmap);

  for (int i = 0; i < sb.st_size; i++) {
    printf("%c", addr[i]);
  }

  printf("\n--------------------------------------------------------------------------------\n");
  
  for (int i = sb.st_size - 1; i >= 0; i--) {
    printf("%c", addr[i]);
  }
  sleep(1000);
  munmap(addr, sb.st_size);

  return EXIT_SUCCESS;
}