deep copy of struct with Pointer Point in C

Question

i need your help!

I like to copy a struct like this:

typedef struct PackageObject_s {
  long  **vertex;          // vertices
  long    num_vertex;      // count of vertices
  long    objectType;      // 
  REAL    r;               // 
  long    bottom[3];       // bounding box bottom vector
  long    top[3];          // bounding box top vector
  long   *start;           // 
  REAL    coverage;        // 
} PackageObject __attribute__ ((aligned));

I try it like this:

static inline void PackageObject_copy(PackageObject *dst, const PackageObject *src) {

  dst->num_vertex = src->num_vertex;
  dst->objectType = src->objectType;
  dst->r          = src->r;
  vec_assign3l(dst->bottom, src->bottom);
  vec_assign3l(dst->top,    src->top);

  // TODO copy **vertex ???

  dst->coverage   = src->coverage;
  dst->coverage   = src->coverage;
}

How can i solve this?

Thank you in advance for your help!!

UPDATE - my solution for deepcopy of vertex - thx for all help:

dst->vertex = (long *)malloc(dst->num_vertex * 3 * sizeof(long));
for (long i=0; i < src->num_vertex; i++) { 
  dst->vertex[i] = (long)malloc(3*sizeof(long)); 
  memcpy(dst->vertex[i],src->vertex[i],3 * sizeof(long)); 
}

Answer 1

I'm going to assume that the vertices are not shared between objects. That is, they belong to the structure in question.

There are two primary cases to consider:

1. Copying into a new object
2. Copying into an existing object

Copying into the new object is straightforward.

1a. Allocate space for <num_vertex> pointers.
1b. Allocate space for each vertex.
2a. Copy <num_vertex> pointers from source to destination.
2b. Copy <num_vertex> vertices from source to destination.

Copying into an existing object is much the same as copying into a new object except that you have to do the following first.

0a. Loop through each element of <vertex> and free the vertex.
0b. Free the array of vertex pointers.
1. Follow the steps for copying into a new object.

Hope this helps.

Answer 2

Original answer:

Assuming vertex points to an array of vertices, and that each vertice contains 3 longs (x,y,z):

dst->vertex = (long **)malloc(dst->num_vertex * 3 * sizeof(long);
memcpy(dst,src,dst->num_vertex * 3 * sizeof(long));  

Update because I realized this might work but isn't clean or especially safe As I mentioned in comments, code would be cleaner if you had

typedef struct vertextag { 
  long x;
  long y;
  long z;
} vertex_type;

And then did: dst->vertex = (vertex_type *)malloc(dst->num_vertex * sizeof(vertex_type); memcpy(dst,src,dst->num_vertex * sizeof(vertex_type));