From: Johannes Sixt <j.sixt@viscovery.net>
Date: Wed, 25 Feb 2009 14:06:14 GMT
Subject: Re: [PATCHv2 4/4] git submodule: Fix handling of // and /.. in paths for added submodules
Message-ID: <49A55056.8020504@viscovery.net>
In-Reply-To: <1235568392-19705-5-git-send-email-git@drmicha.warpmail.net>

Michael J Gruber schrieb:
> @@ -167,6 +167,12 @@ cmd_add()
>  	;;
>  	esac
>  
> +	# simplify multiple /
> +	path=$(echo "$path" | sed -e 's|/\+|/|g')

I think we have so far avoided \+ in sed expressions for portability reasons.

> +
> +	# resolve /.. (add trailing / for matching /..$)
> +	path=$(echo "$path/" | sed -e 's|\([^/]*\)/../||g')

This does not work if there are more than two ../ in a row:

	$ echo a/b/c/../../d | sed -e 's|\([^/]*\)/\.\./||g'
	a/b/../d

(and make this /\.\./ instead of /../).

> +
>  	# strip superfluous ./ from path
>  	path=$(echo "$path" | sed -e 's|^\(\./\)*||' -e's|/\./|/|g')

The latter two transformations should be swapped; otherwise you would
transform foo/./../bar into foo/bar.

Perhaps it's now time to write this as:

	# normalize path
	path=$(printf '%s\n' "$path" |
		 sed -e '
			# simplify multiple /
			s|//*|/|g
			# strip superfluous ./
			s|^\(\./\)*||
			s|/\./|/|g
			# resolve /..
			s|\([^/]*\)/\.\./||g
			# strip trailing slashes
			s|/*$||
		')

But unless you know how to solve the ../../ case with a sed program, I
suggest that you keep things simple and take care only of the common cases.

-- Hannes