Re: How should we deal with actual hush odd behavior?

[Tom Rini <trini@konsulko.com>]

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On Fri, Aug 20, 2021 at 12:22:22PM -0600, Simon Glass wrote:
> Hi Francis,
> 
> On Fri, 20 Aug 2021 at 10:12, Francis Laniel
> <francis.laniel@amarulasolutions.com> wrote:
> >
> > Hi.
> >
> >
> > I hope you are fine and the same for your family and friends.
> >
> > In July, a proposal to add a new shell for U-Boot was posted on the mailing
> > list [1].
> > The community discussed a lot about this changes, some people did not agree
> > with it because the new shell is not compatible with the actual one (hush)
> > [2].
> > So, a proposal to update U-Boot actual hush to follow what they currently have
> > in Busybox was made [3].
> >
> > Porting 2021 Busybox hush to U-Boot seems, for me, to be a good idea as we
> > would benefit from Busybox bug fixes as well as being compatible with actual
> > hush (in theory).
> > We could also add new features to U-Boot hush, like functions, as they were
> > added to Busybox.
> >
> > Nonetheless, the idea of this port is to be compatible.
> > In practice, I noted some cases when this is actually not the case.
> > The first one can be related to how && and || operators were handled in hush.
> > So, the following: false && false || true
> > Returns 0 on Busybox 2021 hush and 1 on U-Boot.
> > The behavior of 2021 is coherent with the definition of these operators [4]:
> > >    The return status of AND and OR lists is the exit
> > >    status of the last command executed in the list.
> > An other example concerns variable expansion, where foo='bar "quux" is
> > expanded to bar quux in U-Boot and bar "quux in Busybox.
> >
> > I do not have a real opinion on the second one, as I think local variable set
> > in U-Boot scripts are quite simple as people do not try to do: foo="bar \"quux
> > 'quuz' \"\"\"corge".
> > The first one is maybe more problematic.
> > Grepping "if test" shows me that the more complex if condition seems to be
> > under the form:
> > if first_test_ AND/OR second_test
> > Here also, people seems to no try to write complex expression like: foo ||
> > bar; echo quux && quuz.
> >
> > So, porting Busybox 2021 hush can solve bugs we have currently in U-Boot, but
> > what if fixing these bugs lead to a board script failing and so a device not
> > booting...
> > I would like to have the opinion of the community on this question.
> 
> My feeling is that we should go with the newer (correct?) behaviour.
> Boards not booting can be found with the existing release process.
> 
> Also if we keep the old hush around for a while people can still use
> it, particularly if it is much smaller.

I would at this point echo this sentiment as well.  Thanks!

-- 
Tom

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