Loading wavefront obj file into an indexed vertex array...

[Syslock]

struct face {
union {
struct {
int x, y, z;
int nx, ny, nz;
int u, t, p;
};
int data[9];
};
};

This isn't even a complete face since you only list one vertex.

Try this:

struct face {

 int num_indices;
 int *vertex_indices;	// dynamically allocated (num_indices)
 int *uv_indices;	// dynamically allocated (num_indices)
 int *normal_indices;	// dynamically allocated (num_indices)
}

Or if you're using STL:

struct face {
 vector<int> vertex_indices;
 vector<int> uv_indices;
 vector<int> normal_indices;
}