#include <sys/mman.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

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


void print_file(char *filename)
{
  int fd = open(filename,O_RDONLY);
  if(fd == -1)
    {
      printf("Cannot open file %s...\n",filename);
      exit(1);
    }

  char buffer[4096];
  int bytes;
  while((bytes = read(fd,buffer,4096)) > 0)
    {
      write(1,buffer,bytes);
    }
}

int main()
{
  printf("Before we create a memory map, here's a view of this process's current memory map:\n");
  print_file("/proc/self/maps");

  int fd = open("/bin/bash",O_RDONLY);
  char *ptr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);

  if(ptr == NULL)
    {
      printf("Cannot mmap!\n");
      exit(1);
    }

  printf("Okay, we have mapped '/bin/bash' in, let's print its first few bytes:\n");

  *(ptr+4) = 0;
  printf("\t Here's the elf: '%s'!\n",ptr+1);
  
  printf("\n=-=-=-=-=-=\n\n");
  printf("Okay, we have created a memory map, here's the new view of this process's current memory map:\n");
  print_file("/proc/self/maps");
  
}