Re: [PATCH] Implement strlcat [BZ#178]

[Paul Eggert <eggert at cs dot ucla dot edu>]

On 11/24/2015 06:30 AM, Florian Weimer wrote:
> +
> +  /* The sum cannot wrap around because both strings would be larger
> +     than half of the address space, which is not possible due to
> +     the restrict qualifier.  */
> +  return dest_length + src_length;

This comment assumes that the address space is flat, e.g., that 
uintptr_t is the same width as size_t. Is this a safe assumption? I 
can't seem to find that assumption documented anywhere. Anyway, assuming 
the assumption is safe, I suggest mentioning it here, e.g.:

  /* The sum cannot wrap around because both strings would be larger
     than half of the address space, which is not possible because of
     the restrict qualifier and because glibc assumes a flat address 
space.  */

I noticed this assumption while preparing a revision to the proposed 
strlcpy+strlcat manual entries, and my next proposal will be based on 
this assumption.