Re: [PATCH v8 02/10] lib: kstrtox: add kstrntoull() helper

[Rodrigo Alencar]

On 26/03/03 02:16PM, Rodrigo Alencar wrote:
> On 26/03/03 03:49PM, Andy Shevchenko wrote:
> > On Tue, Mar 03, 2026 at 01:27:07PM +0000, Rodrigo Alencar via B4 Relay wrote:
> > 
> > > Add kstrntoull() function, which converts a string to an ULL with a max
> > > character limit. The function is an alternative integer parsing function
> > > that does not require a null-terminated string. It becomes a better option
> > 
> > null -->  NUL
> > 
> > > over simple_strtoull() or kstrtoull() when parsing integers from a buffer
> > > with custom delimiters without having to create temporary copies.
> > > The function is consumed inside the implementation _kstrtoull(),
> > > promoting reuse.
> > 
> > But this will not properly convert 0000000000000000000000000000000000000000100,
> > for example, if the max_chars say set to 20.
> 
> Why would I want that? truncation will happen in the case and the value will
> be zero. max_chars can be zet to INT_MAX/SIZE_MAX if you want to get 100.
> 
> > Also kstrto*() have a common idea behind to consume the only \n and allowed
> > digits. This (naming) doesn't fit into the kstrto*() category.
> 
> mmm ok, but include/linux/kstrtox.h is the right place for this? how about just
> strntoull()? I feel like a safe_ prefix does not make much sense if it is
> only to differentiate from simple_strto*(), which should have been safe at
> the first place.

Also kstrntoull() does not really match kstrto*(), as the 'n' is often used
to indicate a stop condition on amount of characters, which would not need
to require any termination character at all.
The 'k' prefix was add to 'strntoull', mostly because the function is being
added to the include/linux/kstrtox.h file. Other names I could think off:
- bounded_strtoull()
- bstrtoull() - 'b' for bounded
- bstrntoull()
- strtoull_bounded()
- strtoull_limit()
- safe_strntoull() - emphasizes overflow safety over simple_strtoull()

Extras considerations:
- Single-letter prefixes (bstrntoull, lstrntoull, etc.) are too cryptic
for a public API
- safe_ prefix is subjective and doesn't describe the actual behavior

kstrntoull() is still my first candidate, other than that it would be
bounded_strtoull().

-- 
Kind regards,

Rodrigo Alencar