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

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Message-ID: <CAOG64qMoDjLer_OgRn2edGLMLMVfA5Lv3CZSU2VeOkgzPWNVUA@mail.gmail.com>
Date:   Sun, 20 Mar 2022 22:50:30 +0700
From:   Alviro Iskandar Setiawan <alviro.iskandar@...weeb.org>
To:     Ammar Faizi <ammarfaizi2@...weeb.org>
Cc:     Willy Tarreau <w@....eu>, "Paul E. McKenney" <paulmck@...nel.org>,
        Nugraha <richiisei@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "GNU/Weeb Mailing List" <gwml@...r.gnuweeb.org>
Subject: Re: [RFC PATCH v1 5/6] tools/nolibc/stdlib: Implement `malloc()`,
 `calloc()`, `realloc()` and `free()`

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