#include <stdio.h>
#include <sys/mman.h>

#define UNPROTECT(addr,len) (mprotect((void*)(addr-(addr%len)),len,PROT_READ|PROT_WRITE|PROT_EXEC))

#ifdef __x86_64
  #define PROGRAM_START_OFFSET 0x400440
  #define DATA_START_OFFSET 0x601000
#else
  #define PROGRAM_START_OFFSET 0x8048000
  #define DATA_START_OFFSET 0x804A020
#endif

void * find_sig(unsigned char * array, int len, void * start, void * end, int offset, int align)    {
  void * pos;
  for (pos = start; pos < end; pos += align) {
    if (memcmp(pos, array, len) == 0)
      return pos + offset;
  }
  return NULL;
}

char I_WANT_SPACE_SIGNATURE[] = "IWANTSPACE";
char HUEBR_SIGNATURE[] = "HUEBR\n";
char printfHUEoffset[] = { 0xBF, 0x00, 0x00, 0x00, 0x00 };

void __attribute__((constructor)) initialize(void) {
  //char *x = 0x6010A8; // Address in empty space of I_WANT_SPACE
  char *x = find_sig(I_WANT_SPACE_SIGNATURE, 10, (void *)DATA_START_OFFSET, (void *)(DATA_START_OFFSET+4096), 0, 1);
  char *huebr = find_sig(HUEBR_SIGNATURE, 6, (void *)DATA_START_OFFSET, (void *)(DATA_START_OFFSET+4096), 0, 1);

  if (x == NULL || huebr == NULL) {
    printf("OH FUCK IT! %p %p\n", x, huebr);
    exit(1);
  }


  printfHUEoffset[1] = (((int)huebr) >> 0) & 0xFF;
  printfHUEoffset[2] = (((int)huebr) >> 8) & 0xFF;
  printfHUEoffset[3] = (((int)huebr) >> 16) & 0xFF;
  printfHUEoffset[4] = (((int)huebr) >> 24) & 0xFF;

  int *z = find_sig(printfHUEoffset, 5, (void *)PROGRAM_START_OFFSET, (void *)(PROGRAM_START_OFFSET+4096),0,1);

  x[0] = 'p';
  x[1] = 'h';
  x[2] = 'p';
  x[3] = '\n';
  x[4] = 0x00;

  UNPROTECT(PROGRAM_START_OFFSET,4096); // 0x400530 is the address of the main() space
  int *t = (((int)z)+1); // mov     edi, offset teste ; "HUEBR\n" - Adress to offset teste
  *t = x;
/*
  x = 0x40056F; // mov     eax, 0 - Before last line
  x[0] = 0x48;
  x[1] = 0xc7;
  x[2] = 0xc0;
  t = x + 3;
  *t = 0x40053A; // Address of start of the main() function excluding the stack pushes.
  x[7] = 0xff;
  x[8] = 0xe0;
  */
}