code review request , storing anything into void* storage area - c

Question

I need help in reviewing following code.
I am trying to store anything into memory allocated ( void *) and retrive the same.
Please take a look at the code and let me know if there is anything wrong, Or if it will not work, of if there is better approach to achieve the same.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
typedef struct __c_object {
void *data;
size_t size;
} c_object;
c_object *new_c_object(void *inObject, size_t obj_size) {
c_object *tmp = (c_object*)malloc(sizeof(c_object));
tmp->size = obj_size;
tmp->data = (void*)malloc(obj_size);
memcpy ( tmp->data, inObject, obj_size);
return tmp;
}
void get_raw_c_object ( c_object *inObject, void **tmp) {
*tmp = (void*)malloc(inObject->size);
memcpy ( *tmp, inObject->data, inObject->size );
}
void delete_c_object ( c_object *inObject ) {
if (inObject ) {
free ( inObject->data );
free ( inObject);
}
inObject = ( c_object *)0;
}
int main() {
int in = 0;
c_object *co = new_c_object ( &in, sizeof(int));
void *ptrOut = (void*)0;
void *ptr = (void*)0;
get_raw_c_object( co , &ptrOut);
printf ( "Interger = [%d]\n", *(int*)ptrOut);
delete_c_object ( co );
float float_in = 10.99;
co = new_c_object ( &float_in, sizeof(float));
get_raw_c_object( co, &ptrOut);
printf ( "Float = [%f]\n", *(float*)ptrOut);
delete_c_object ( co );
int *ptr_int = ( int*) malloc ( sizeof ( int ));
in = 999;
ptr = &in;
co = new_c_object ( ptr, sizeof(int*));
get_raw_c_object( co,&ptrOut );
printf ( "Interger Pointer = [%d]\n", *(int*)ptrOut);
delete_c_object ( co );
char *inStr = "Hello Hello Hello";
char *inStrDup = _strdup (inStr);
co = new_c_object ( inStrDup, strlen(inStr) + 1);
free ( inStrDup );
get_raw_c_object( co ,&ptrOut);
printf ( "Character = [%s]\n", (char*)ptrOut);
delete_c_object ( co );
char *inStr2 = "Hello Hello Hello";
co = new_c_object ( inStr2, strlen(inStr2) + 1);
get_raw_c_object( co,&ptrOut );
printf ( "Character = [%s]\n", (char*)ptrOut);
delete_c_object ( co );
}

Answer 1

One Problem in the code it that get_raw_c_object( co, &ptrOut); allocates memory with malloc (returned by ptrOut) yet you never free that memory!
I don't exactly know what you are trying to achive but take a look at the following pseudo C/C++ code. Maybe it can help you:
typedef struct Variadic {
enum DataType type;
union {
char charData;
short shortData;
int intData;
unsigned int uintData;
char *charPtrData;
[...]
} data;
};
// functions for allocation and destruction
Variadic* new_variadic();
void delete_variadic(Variadic*);
// using the variadic
Variadic *a = new_variadic;
a->type = TYPE_INT;
a->data.intData = 10;
In case of a char* string delete_variadic would also delete the contained string.

Answer 2

You do really much copying with your objects. So I hope that all the types you want to store support being copied. One counter-example that comes to mind is a node of a doubly linked list, because there are some pointers outside that point to that exact address.
But as long as your data is not referenced from the outside, this works. You also need to make sure that your program has enough memory available, otherwise you run into undefined behavior as soon as malloc returns NULL.
In the delete_c_object function you don't need to zero out inObject. That statement has no effect at all.
The section for the integer pointer is missing one level of pointers. It looks just like the integer section.