[U-Boot] escape sequence issue

[Wolfgang Denk]

Dear Frans Meulenbroeks,

In message <CACW_hTa_8=u=QppRO9SnAycPqu786XP-md7R3BEFjcjwnYjWxQ at mail.gmail.com> you wrote:
>
> setenv tst "setexpr.b mode *1000 \& 0xe8"
> and I do a
> printenv tst
> I get:
> tst=setexpr.b mode *1000 \& 0xe8
> Note: one slash.
> But if I do a printenv without argument I get
> tst=setexpr.b mode *1000 \\& 0xe8
> Note the two slashes.

Yes, this is a known (not widely, but still) inconsistency.  I didn';t
know of a good way to fix it, so I left it unchanged.

> Reason is that printenv when reading one entry directly fetches it from the
> hash table; no processing of escape sequences is done, while printenv uses
> hexport_r (or so) which does replace all \ with \\

Correct.

> Not sure what the best solution is to resolve this (so no patch)
> Perhaps printenv should not use hexport_r, or maybe hexport_r should have
> an additional argument whether or not to escape backslashes.

The reason to use hexport_r() here is so we are able to copy & past
the output of printenv into a text file, which later can be used as is
with "env import".

> Is it desired to have escape sequence handling while importing the ENV
> default settings. Personally I'm inclined to say no. I can understand that
> cpp eats up a \ but it is somewhat hard to understand that if one on the
> cmd line types a cmd with a single \ it should become \\\\ in the default
> env.

...in the default env settings as processed in a C file though CPP.

I think you should use the external storage representation as
reference, i. e. what U-Boot creates with env export, and what it
reads with env import.

There must be a way to deal with escapes. The current implementation
tried to compromize between ideally no changes to previous behaviour
on one side (even maintaining binary compatibility to the stored
environments olf older versions), and a consistent way to import and
export variable settings on the other side.

> PS: please keep me on cc as I am not on the list)

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Best regards,

Wolfgang Denk

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