/**
 * @file   realloc.c
 * @brief  realloc implementation.
 */

#include "libft.h"
#include "malloc.h"
#include "malloc_internal.h"

static t_chunk *
_s_ptr_to_chunk (void *ptr)
{
  return ((t_chunk *)((char *)ptr - ALIGN (sizeof (t_chunk))));
}

void *
realloc (void *ptr, size_t size)
{
  t_chunk *chunk;
  void *new_ptr;
  size_t copy_size;

  if (!ptr)
    return (malloc (size));
  if (size == 0)
    {
      free (ptr);
      return (NULL);
    }
  chunk = _s_ptr_to_chunk (ptr);
  if (chunk->size >= ALIGN (size))
    return (ptr);
  new_ptr = malloc (size);
  if (!new_ptr)
    return (NULL);
  copy_size = chunk->size;
  if (copy_size > size)
    copy_size = size;
  ft_memcpy (new_ptr, ptr, copy_size);
  free (ptr);
  return (new_ptr);
}