Re: [PATCH v2] misra: deviate C library-style functions from Misra C:2012 rule 11.8

[Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>]

On 11/2/26 12:37, Dmytro Prokopchuk wrote:
> On 10/26/26 13:09, Jan Beulich wrote:
> > On 19.10.2026 12:41, Dmytro Prokopchuk1 wrote:
> > > bsearch(), memchr(), strchr(), strpbrk(), strrchr() and strstr() all
> > > accept a const pointer/object but return a non-const pointer to the
> > > matched element or byte, matching their standard C library interfaces.
> > > The casts in these implementations strip const so that callers searching
> > > a non-const object get back a mutable pointer. Fixing this would require
> > > changing the public API, so document these uses as deviations instead.
> > Imo "public API" is misleading here, as it could mean "public interface",
> > which isn't affected here at all. Then ...
> Agreed. I'll reword the last sentence to:
> "Avoiding the casts would require deviating from the standard C library
> prototypes of these functions, so document these uses as deviations
> instead."
>
> > > Update docs/misra/rules.rst to note that this class of double-use
> > > library functions is deviated on a per-function basis.
> > >
> > > Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
> > Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> >
> > Albeit there another minor remark:
> >
> > > --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> > > @@ -450,6 +450,14 @@ write or not"
> > >   - 
> > > config=MC3A2.R11.8,reports+={safe,"any_area(any_loc(file(hvm_guestcopy)&&text(^.*__hvm_copy.*HVMCOPY_to_guest doesn't modify.*$)))"}
> > >   -doc_end
> > > +-doc_begin="Functions bsearch(), memchr(), strchr(), strpbrk(), 
> > > strrchr() and
> > > +strstr() accept a const pointer/object and return a non-const 
> > > pointer to the
> > > +matched element or byte, matching their standard C library 
> > > interfaces. The
> > > +casts in these implementations strip const so that a search of a 
> > > non-const
> > > +object yields a mutable pointer. This use is deemed safe."
> > > +-config=MC3A2.R11.8,reports+={safe,"any_area(any_loc(file(^xen/ 
> > > include/xen/bsearch\\.h$||^xen/lib/(memchr|strchr|strpbrk|strrchr| 
> > > strstr)\\.c$)))"}
> > > +-doc_end
> > Can't we fold strchr and strrchr here, e.g. as simple as (memchr| 
> > str+chr|strpbrk|strstr)?
Sure, will do in v3.

> > Jan
BR, Dmytro.