Re: [PATCH 1/5] 9pfs: introduce P9Array

[Christian Schoenebeck]

On Freitag, 1. Oktober 2021 17:16:47 CEST Daniel P. Berrangé wrote:
> On Fri, Oct 01, 2021 at 04:26:17PM +0200, Christian Schoenebeck wrote:
> > Implements deep auto free of arrays while retaining common C-style
> > squared bracket access. Main purpose of this API is to get rid of
> > error prone individual array deallocation pathes in user code, i.e.
> > 
> > turning something like this:
> >   void doSomething(size_t n) {
> >   
> >       Foo *foos = malloc(n * sizeof(Foo));
> >       for (...) {
> >       
> >           foos[i].s = malloc(...);
> >           if (...) {
> >           
> >               goto out;
> >           
> >           }
> >       
> >       }
> >   
> >   out:
> >       if (...) {
> >       
> >           for (...) {
> >           
> >               /* deep deallocation */
> >               free(foos[i].s);
> >           
> >           }
> >           /* array deallocation */
> >           free(foos);
> >       
> >       }
> >   
> >   }
> > 
> > into something more simple and safer like:
> >   void doSomething(size_t n) {
> >   
> >       P9ARRAY_REF(Foo) foos = NULL;
> >       P9ARRAY_NEW(Foo, foos, n);
> >       for (...) {
> >       
> >           foos[i].s = malloc(...);
> >           if (...) {
> >           
> >               return; /* array auto freed here */
> >           
> >           }
> >       
> >       }
> >       /* array auto freed here */
> >   
> >   }
> 
> As explained before, I'm against the idea of introducing new ways
> to automatically free local variables that are not using g_auto*
> functionality. It is not following the QEMU wide coding style
> that is documented.

Yes, your concerns are linked in the cover letter. And I also made it clear 
that what you suggested does not fit either. So my position has not changed.

Best regards,
Christian Schoenebeck