Reverse Engineering for Beginners

CHAPTER 51. C++ CHAPTER 51. C++

struct a t1;

t1.x=1;

t1.y=2;

l.push_front (t1);

t1.x=3;

t1.y=4;

l.push_front (t1);

t1.x=5;

t1.y=6;

l.push_back (t1);

printf ("* 3-elements list:\n");

dump_List_val((unsigned int*)(void*)&l);

std::list<struct a>::iterator tmp;

printf ("node at .begin:\n");

tmp=l.begin();

dump_List_node ((struct List_node *)*(void**)&tmp);

printf ("node at .end:\n");

tmp=l.end();

dump_List_node ((struct List_node *)*(void**)&tmp);

printf ("* let's count from the begin:\n");

std::list<struct a>::iterator it=l.begin();

printf ("1st element: %d %d\n", (*it).x, (*it).y);

it++;

printf ("2nd element: %d %d\n", (*it).x, (*it).y);

it++;

printf ("3rd element: %d %d\n", (*it).x, (*it).y);

it++;

printf ("element at .end(): %d %d\n", (*it).x, (*it).y);

printf ("* let's count from the end:\n");

std::list<struct a>::iterator it2=l.end();

printf ("element at .end(): %d %d\n", (*it2).x, (*it2).y);

it2--;

printf ("3rd element: %d %d\n", (*it2).x, (*it2).y);

it2--;

printf ("2nd element: %d %d\n", (*it2).x, (*it2).y);

it2--;

printf ("1st element: %d %d\n", (*it2).x, (*it2).y);

printf ("removing last element...\n");
l.pop_back();
dump_List_val((unsigned int)(void)&l);
};

GCC

Let’s start with GCC.

When we run the example, we’ll see a long dump, let’s work with it in pieces.

• empty list:
  ptr=0x0028fe90 _Next=0x0028fe90 _Prev=0x0028fe90 x=3 y=0

Here we see an empty list. Despite the fact it is empty, it has one element with garbage (AKAdummy node) inxandy. Both
the “next” and “prev” pointers are pointing to the self node: