Re: [RFC PATCH v1 5/6] tools/nolibc/stdlib: Implement `malloc()`, `calloc()`, `realloc()` and `free()`

[Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org>]

On Sun, Mar 20, 2022 at 4:37 PM Ammar Faizi wrote:
> +void *realloc(void *old_ptr, size_t new_size)
> +{
> +       struct nolibc_heap *heap;
> +       void *ret;
> +
> +       if (!old_ptr)
> +               return malloc(new_size);
> +
> +       ret = malloc(new_size);
> +       if (__builtin_expect(!ret, 0))
> +               return NULL;
> +
> +       heap = container_of(old_ptr, struct nolibc_heap, user_p);
> +       memcpy(ret, heap->user_p, heap->len);
> +       munmap(heap, heap->len);
> +       return ret;
> +}

This better be simplified like this, so only have 1 malloc() call that
applies to both branches.

  void *realloc(void *old_ptr, size_t new_size)
  {
         struct nolibc_heap *heap;
         void *ret;

         ret = malloc(new_size);
         if (__builtin_expect(!ret, 0))
                 return NULL;

         if (!old_ptr)
                 return ret;

         heap = container_of(old_ptr, struct nolibc_heap, user_p);
         memcpy(ret, heap->user_p, heap->len);
         munmap(heap, heap->len);
         return ret;
  }

-- Viro