Re: [SOLVED] Libtool/zsh quoting problem: a zsh... bug?

[Andrey Borzenkov <arvidjaar@newmail.ru>]

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On Saturday 11 February 2006 21:14, Wayne Davison wrote:
> On Sat, Feb 11, 2006 at 01:21:43PM +0300, Andrey Borzenkov wrote:
> > See this thread: <http://www.zsh.org/mla/workers/2002/msg00542.html>;
> > there was an attempt to fix it in 16949 but apparently it was incomplete
> > and never went in.
>
> I just took a look at that code using Peter's old patch as a start, and
> the assertion that the quotes have been stripped out is not quite true:
> there are still Dnull and Snull characters remaining which indicate that
> there used to be a double- or single-quotes present.  This allows us to
> check the string.  An overly simple version is this:
>
> --- subst.c	6 Feb 2006 11:57:06 -0000	1.44
> +++ subst.c	11 Feb 2006 18:07:23 -0000
> @@ -2012,6 +2012,8 @@ paramsubst(LinkList l, LinkNode n, char
>  		 */
>  		multsub(&val, (aspar ? NULL : &aval), &isarr, NULL);
>  		copied = 1;
> +		if (spbreak && (*s == Dnull || *s == Snull))
> +		    spbreak = 0;
>  	    }
>  	    break;
>  	case ':':
>
> This will turn off word-splitting if the string started with a single or
> a double quote.  This is incomplete because the arg may be something
> more complicated (such as: 'one' 'two' 'three four'), but it seems
> better than what we have now.
>

I am not at all sure that the above is valid in POSIX shell. The word in 
${var+word} is a token, and token is delimited by the first blank; so while 
you can do ${var+$(any command with blank)} (because command substitution 
forms token by itself) you apparently cannot do ${var+foo bar baz}.

That's said, bash accepts the above just fine and correctly preserves quoting:

bash-3.1$ args()
> {
> while [[ $# -gt 0 ]]; do
> echo "$1"
> shift
> done
> }
bash-3.1$ args ${var+"foo bar" baz}
foo bar
baz

So assuming my interpretation is correct, we have two options:

- -  turn the above on only is sh (POSIX?) emulation mode on assumption that 
multiple words on the right side are invalid anyway

- - attempt to fix it to be compatible with bash i.e. correctly preserve 
individual quoted words.

Is it possible to recursively call expansion on rhs word? According to SUS: 
"word shall be subjected to tilde expansion, parameter expansion, command 
substitution, and arithmetic expansion." so recursively calling expansion 
looks the right way to go.

> One question I have is what to do about ${=1:"$@"}?  In the patch above,
> I chose to let the double quotes override the '='.  If that is not
> desired, change the new "if" to only trigger disallow an spbreak of 2:
>
> +		if (spbreak == 1 && (*s == Dnull || *s == Snull))
>
As long as it is documented ...

- -andrey
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