Subject: Re: [PATCH 1/3] pathspec: catch prepending :(prefix) on pathspec with short magic

From: Junio C Hamano <[email-masked]>
Date: Thu, 05 Sep 2013 11:39:56 -0700

Nguyễn Thái Ngọc Duy  <[email-masked]> writes:

> :(prefix) is in the long form. Suppose people pass :!foo with '!'
> being the short form of magic 'bar', the code will happily turn it to
> :(prefix..)!foo, which makes '!' part of the path and no longer a magic.
>
> The correct form must be ':(prefix..,bar)foo', but as so far we
> haven't had any magic in short form yet (*), the code to convert from
> short form to long one will be inactive anyway. Let's postpone it
> until a real short form magic appears.
>
> (*) The short form magic '/' is a special case and won't be caught by
> this die(), which is correct. When '/' magic is detected, prefixlen is
> set back to 0 and the whole "if (prefixlen..)" block is skipped.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
> ---
>  fixes on top of nd/magic-pathspec.
>
>  pathspec.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/pathspec.c b/pathspec.c
> index d9f4143..62fde50 100644
> --- a/pathspec.c
> +++ b/pathspec.c
> @@ -231,7 +231,9 @@ static unsigned prefix_pathspec(struct pathspec_item *item,
>  		const char *start = elt;
>  		if (prefixlen && !literal_global) {
>  			/* Preserve the actual prefix length of each pattern */
> -			if (long_magic_end) {
> +			if (short_magic)
> +				die("BUG: prefixing on short magic is not supported");
> +			else if (long_magic_end) {
>  				strbuf_add(&sb, start, long_magic_end - start);
>  				strbuf_addf(&sb, ",prefix:%d", prefixlen);
>  				start = long_magic_end;

Good.

I wonder if we should start thinking about removing the big
"NEEDSWORK" comment in front of this function.

Also the pathspec_magic[] array was the table-driven way that was
meant to be enhanced to fit future needs to parse all supported
types of pathspec magic, but it seems that "prefix:12" magic is
implemented using a custom/special case code.  We may want to see if
we want to enrich the parser to fold this to match the table-driven
approach better someday---this is not urgent as we are not adding
any new pathspec magic now.

Will queue.  Thanks.