Re: [PATCH v2] malloc_stats(): Fix `unsigned int` overflow

[DJ Delorie <dj@redhat.com>]

Niklas Hambchen <mail@nh2.me> writes:
> @@ -5374,7 +5374,7 @@ __malloc_stats (void)
>  {
>    int i;
>    mstate ar_ptr;
> -  unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
> +  size_t in_use_b = mp_.mmapped_mem, system_b = in_use_b;

Ok.

> @@ -5389,8 +5389,8 @@ __malloc_stats (void)
>        __libc_lock_lock (ar_ptr->mutex);
>        int_mallinfo (ar_ptr, &mi);
>        fprintf (stderr, "Arena %d:\n", i);
> -      fprintf (stderr, "system bytes     = %10u\n", (unsigned int) mi.arena);
> -      fprintf (stderr, "in use bytes     = %10u\n", (unsigned int) mi.uordblks);
> +      fprintf (stderr, "system bytes     = %10zu\n", mi.arena);
> +      fprintf (stderr, "in use bytes     = %10zu\n", mi.uordblks);

Ok.

> -  fprintf (stderr, "system bytes     = %10u\n", system_b);
> -  fprintf (stderr, "in use bytes     = %10u\n", in_use_b);
> -  fprintf (stderr, "max mmap bytes   = %10lu\n",
> -           (unsigned long) mp_.max_mmapped_mem);
> +  fprintf (stderr, "system bytes     = %10zu\n", system_b);
> +  fprintf (stderr, "in use bytes     = %10zu\n", in_use_b);
> +  fprintf (stderr, "max mmap bytes   = %10zu\n", mp_.max_mmapped_mem);

This needs a cast to (size_t) as max_mmapped_mem is INTERNAL_SIZE_T,
which may be smaller than size_t.

> -  fprintf (stderr, "max mmap regions = %10u\n", (unsigned int) mp_.max_n_mmaps);
> +  fprintf (stderr, "max mmap regions = %10d\n", mp_.max_n_mmaps);

This causes a negative number to be printed when max_n_mmaps increments
past 2^31, where using "u" defers bad results until 2^32.  So IMHO this
one is a regression, not a fix.