[PATCH v2] Makefile: fix generating environment file

[Oleksandr Suvorov <oleksandr.suvorov@toradex.com>]

On Wed, Apr 21, 2021 at 11:56 PM Rasmus Villemoes
<rasmus.villemoes@prevas.dk> wrote:
>
> On 21/04/2021 17.21, Oleksandr Suvorov wrote:
> > Hi Rasmus,
> >
> > On Wed, Apr 21, 2021 at 12:34 AM Rasmus Villemoes
> > <rasmus.villemoes@prevas.dk> wrote:
> >>
> >> On 20/04/2021 23.10, Oleksandr Suvorov wrote:
> >>> Hi Rasmus,
> >>>
> >>> Thanks for your feedback!
> >>> Yes, I noted that there were no possible situations with the trailing
> >>> code != 0x00, but simply removing the additional trailing 0x00
> >>> gives us an empty array default_environment[] for the empty defaultenv file.
> >>> I need to test whether this case is handled in u-boot properly and
> >>> then prepare the next patch version :P
> >>
> >> No, I'm not suggesting removing the trailing nul byte, it very much has
> >> to be there - the binary format of the environment is a sequence of
> >> nul-terminated C strings of the key=value form, concatenated
> >> back-to-back, terminated by an empty string.
> >
> > (/me saying: never answer at night, never answer at night, never
> > answer at night  :-D)
> >
> >>
> >> What I'm suggesting is to take the input file
> >>
> >> ===
> >> foo=bar
> >>
> >> # Set our IP address
> >> ip=1.2.3.4
> >> ===
> >>
> >> do the comment- and empty-line stripping (the two first greps), and then
> >> after that add an extra empty line
> >>
> >> ===
> >> foo=bar
> >> ip=1.2.3.4
> >>
> >> ===
> >>
> >> and then feed that to the 'replace \n by nul bytes' | 'delete
> >> backslash+nul+whitespace' | xxd pipe. That way there's always that
> >> trailing nul on the input to xxd, i.e. in the example above, we would
> >> feed foo=bar\0ip-1.2.3.4\0\0 into xxd, while with an initially empty
> >> file xxd would just receive that single nul byte.
> >>
> >> It's just that I think terminating the sequence of key=value lines by an
> >> empty line more exactly matches the binary format.
> >
> > Sure, now I see. Your solution is more straight and clear.
> > Unfortunately, it doesn't work :)
>
> Yeah, I didn't really expect it to. Ah, it's because "set -e" is in
> effect, so in
>
>         ( { grep -v '^#' | grep -v '^$$' ; echo '' ; } | \
>
> the return value of the  grep -v '^#' | grep -v '^$$' pipeline is that
> of the second grep, and when there's no input lines that match (such as,
> with an empty input file), that's an EXIT_FAILURE. So the whole subshell
> exits at that point, and nothing gets written to defaultenv_autogenerated.h.
>
> Doing
>
> define filechk_defaultenv.h
>         ( { grep -v '^#' | grep -v '^$$' || true ; echo '' ; } | \
>          tr '\n' '\0' | \
>          sed -e 's/\\\x0\s*//g' | \
>          xxd -i ; )
> endef
>
> seems to work.

So will you post your own patch?

> Rasmus


-- 
Best regards
Oleksandr Suvorov

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