git-submodule - make "submodule add" more strict, and document it

This change makes "submodule add" much more strict in the arguments it
takes, and is intended to address confusion as recently noted on the
git-list. With this change, the required syntax is:

	$ git submodule add URL path

Specifically, this eliminates the form

	$ git submodule add URL

which was confused by more than one person as

	$ git submodule add path

With this patch, the URL locating the submodule's origin repository can be
either an absolute URL, or (if it begins with ./ or ../) can express the
submodule's repository location relative to the superproject's origin.

This patch also eliminates a third form of URL, which was relative to the
superproject's top-level directory (not its repository).  Any URL that was
neither absolute nor matched ./*|../* was assumed to point to a
subdirectory of the superproject as the location of the submodule's origin
repository.  This URL form was confusing and does not seem to correspond
to an important use-case.  Specifically, no-one has identified the need to
clone from a repository already in the superproject's tree, but if this is
needed it is easily done using an absolute URL: $(pwd)/relative-path.  So,
no functionality is lost with this patch. (t6008-rev-list-submodule.sh did
rely upon this relative URL, fixed by using $(pwd).)

Following this change, there are exactly four variants of
submodule-add, as both arguments have two flavors:

URL can be absolute, or can begin with ./|../ and thus names the
submodule's origin relative to the superproject's origin.

Note: With this patch, "submodule add" discerns an absolute URL as
matching /*|*:*: e.g., URL begins with /, or it contains a :.  This works
for all valid URLs, an absolute path in POSIX, as well as an absolute path
on Windows).

path can either already exist as a valid git repo, or will be cloned from
the given URL.  The first form here eases creation of a new submodule in
an existing superproject as the submodule can be added and tested in-tree
before pushing to the public repository.  However, the more usual form is
the second, where the repo is cloned from the given URL.

This specifically addresses the issue of

	$ git submodule add a/b/c

attempting to clone from a repository at "a/b/c" to create a new module
in "c". This also simplifies description of "relative URL" as there is now
exactly *one* form: a URL relative to the parent's origin repo.

Signed-off-by: Mark Levedahl <mlevedahl@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 20 insertions, 35 deletions

diff --git a/git-submodule.sh b/git-submodule.sh
index 099a7d7560..c2ce2fbe8a 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -5,7 +5,7 @@
 # Copyright (c) 2007 Lars Hjemli
 
 USAGE="[--quiet] [--cached] \
-[add <repo> [-b branch]|status|init|update [-i|--init]|summary [-n|--summary-limit <n>] [<commit>]] \
+[add <repo> [-b branch] <path>]|[status|init|update [-i|--init]|summary [-n|--summary-limit <n>] [<commit>]] \
 [--] [<path>...]"
 OPTIONS_SPEC=
 . git-sh-setup
@@ -27,18 +27,6 @@ say()
 	fi
 }
 
-# NEEDSWORK: identical function exists in get_repo_base in clone.sh
-get_repo_base() {
-	(
-		cd "`/bin/pwd`" &&
-		cd "$1" || cd "$1.git" &&
-		{
-			cd .git
-			pwd
-		}
-	) 2>/dev/null
-}
-
 # Resolve relative url by appending to parent's url
 resolve_relative_url ()
 {
@@ -115,7 +103,7 @@ module_clone()
 #
 # Add a new submodule to the working tree, .gitmodules and the index
 #
-# $@ = repo [path]
+# $@ = repo path
 #
 # optional branch is stored in global branch variable
 #
@@ -150,16 +138,27 @@ cmd_add()
 	repo=$1
 	path=$2
 
-	if test -z "$repo"; then
+	if test -z "$repo" -o -z "$path"; then
 		usage
 	fi
 
-	# Guess path from repo if not specified or strip trailing slashes
-	if test -z "$path"; then
-		path=$(echo "$repo" | sed -e 's|/*$||' -e 's|:*/*\.git$||' -e 's|.*[/:]||g')
-	else
-		path=$(echo "$path" | sed -e 's|/*$||')
-	fi
+	# assure repo is absolute or relative to parent
+	case "$repo" in
+	./*|../*)
+		# dereference source url relative to parent's url
+		realrepo=$(resolve_relative_url "$repo") || exit
+		;;
+	*:*|/*)
+		# absolute url
+		realrepo=$repo
+		;;
+	*)
+		die "repo URL: '$repo' must be absolute or begin with ./|../"
+	;;
+	esac
+
+	# strip trailing slashes from path
+	path=$(echo "$path" | sed -e 's|/*$||')
 
 	git ls-files --error-unmatch "$path" > /dev/null 2>&1 &&
 	die "'$path' already exists in the index"
@@ -174,20 +173,6 @@ cmd_add()
 			die "'$path' already exists and is not a valid git repo"
 		fi
 	else
-		case "$repo" in
-		./*|../*)
-			# dereference source url relative to parent's url
-			realrepo=$(resolve_relative_url "$repo") || exit
-			;;
-		*)
-			# Turn the source into an absolute path if
-			# it is local
-			if base=$(get_repo_base "$repo"); then
-				repo="$base"
-			fi
-			realrepo=$repo
-			;;
-		esac
 
 		module_clone "$path" "$realrepo" || exit
 		(unset GIT_DIR; cd "$path" && git checkout -q ${branch:+-b "$branch" "origin/$branch"}) ||