Re: [PATCH v3 1/5] string: Add strprefix(), and deprecate str_has_prefix()

[Joe Perches]

On Tue, 2026-11-10 at 16:33 +0100, Alejandro Colomar wrote:
> As Bartosz reported, str_has_prefix() has a bug: it can't differentiate
> between an empty prefix matching an empty string from a non-matching
> prefix.  This is a fundamental design flaw in this API, and not
> something that can be fixed.
> 
> As always, this is a consequence of choosing sizes instead of pointers.
> Sizes are often the wrong choice.  In this specific case, pointers are
> more capable of differentiating these cases, as NULL is a special
> sentinel value that doesn't need to overload a valid value.
> 
> Let's implement strprefix(), a function that returns a pointer
> right after the prefix if found, and a null pointer if not found.
> 
> We'll slowly migrate existing code from str_has_prefix() to strprefix().

Most uses of str_has_prefix could use the existing strstarts.