CT-NG 1.11.1: Using Spaces in *_EXTRA_CONFIG

[Yann E. MORIN]

Ben, All,

On Thursday 12 May 2011 22:23:42 Ben Baattheid wrote:
> I have an issue with crosstool-NG 1.11.1: When spaces are used for
> parameters inside *_EXTRA_CONFIG, the corresponding configure commands
> fail.

Yes, indeed. That's a limitation. The problem is that we want to:
 - allow passing more than one configure argument
 - allow for arguments with spaces

But because kconfig only supports strings (and tristates), we have to make
a choice between the two requirements. I initially choose to favour passing
multiple arguments, and thus discarded the ability to pass argmuents with
spaces in them.

So, when using the *_EXTRA_CONFIG variables, crosstool-NG does not enclose
expansion between double quotes.

[--SNIP many examples--]
> As you can see, the --with-pkgversion option gets split in all cases
> because of the space, independently of the quoting choice, which
> breeds the errors.

Yes. Sorry... :-/

So basically, if we want to support both multiple args *and* args with
spaces in them, then we have to come up with a few tricks. And I have a
few ideas.

The first, relatively easy one:
 - use a character as a separator between args. The pipe '|' seems like
   a rather good candidate here. I can't really see args with pipes in
   them, and pipes are commonly used in AsciiArt to create tables, so
   hard-core programmers (they are our target audience, aren't they? ;-])
   would not be too disoriented.
 - then *_EXTRA_CONFIG variables (and potentially others) are split up
   around pipes to create bash-style arrays. I have a mostly-working
   code snippet that does the trick (see below).
 - code that needs to split such variables would call a function, eg.
   somewhere in the binutils build function:
      CT_SplitVar CT_BINUTILS_EXTRA_CONFIG extra_config
 - works in all cases, but breaks existing .config files

The second, relatively complex, but maybe more easy to use from an
end-user perspective (or maybe not):
 - allow for bash-style arrays assignments in the menuconfig, such as
   (note the nultiple conflicting double-quotes):
     CT_BINUTILS_EXTRA_CONFIG="--arg1="val with space" --arg2=no_space"
 - of course, this implies that .config is no longer sourceable as-is and
   needs a bit of love+sed so as to transform such variables into proper
   bash-style array assignments:
     CT_BINUTILS_EXTRA_CONFIG=( --arg1="val with space" "--arg2=no_space" )
 - then the code that needs that variable should simply treat it as a
   bash-style array.
 - much more impact on the infrastructure code, and not very robust.

The third idea would be to make kconfig aware of array variables.
Well, no... Forget this idea. :-]

No need to say that I like the first idea much more than the second one.
Thoughts?

Regards,
Yann E. MORIN.

PS. Mostly-working code snippet to split variables, but breaks on empty
    input variable for now. Easy to fix.
    split_me() {
      local var_to_split="${1}"
      local out_var="${2}"
      local ___foo
      local -a ___bar

      eval ___foo="\${${var_to_split}}\|"
      while [ -n "${___foo}" ]; do
        ___bar+=( "${___foo%%|*}" )
        ___foo="${___foo#*|}"
      done
      eval ${out_var}=\(\"\${___bar[@]}\"\)
    }
I'll see what I can do about it during the WE...

Regards,
Yann E. MORIN.

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