git-submodule: fix subcommand parser

The subcommand parser of "git submodule" made its subcommand
names reserved words.  As a consequence, a command like this:

    $ git submodule add init update

which is meant to add a submodule called 'init' at path 'update'
was misinterpreted as a request to invoke more than one mutually
incompatible subcommands and incorrectly rejected.

This patch fixes the issue by stopping the subcommand parsing at
the first subcommand word, to allow the sample command line
above to work as expected.

It also introduces the usual -- option disambiguator, so that a
submodule at path '-foo' can be updated with

    $ git submodule update -- -foo

without triggering an "unrecognized option -foo" error.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

git-submodule.sh

@@ -9,11 +9,8 @@ OPTIONS_SPEC=
 . git-sh-setup
 require_work_tree
 
-add=
+command=
 branch=
-init=
-update=
-status=
 quiet=
 cached=
 
@@ -123,6 +120,32 @@ module_clone()
 #
 cmd_add()
 {
+	# parse $args after "submodule ... add".
+	while test $# -ne 0
+	do
+		case "$1" in
+		-b | --branch)
+			case "$2" in '') usage ;; esac
+			branch=$2
+			shift
+			;;
+		-q|--quiet)
+			quiet=1
+			;;
+		--)
+			shift
+			break
+			;;
+		-*)
+			usage
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+
 	repo=$1
 	path=$2
 
@@ -176,6 +199,27 @@ cmd_add()
 #
 cmd_init()
 {
+	# parse $args after "submodule ... init".
+	while test $# -ne 0
+	do
+		case "$1" in
+		-q|--quiet)
+			quiet=1
+			;;
+		--)
+			shift
+			break
+			;;
+		-*)
+			usage
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+
 	git ls-files --stage -- "$@" | grep -e '^160000 ' |
 	while read mode sha1 stage path
 	do
@@ -209,6 +253,27 @@ cmd_init()
 #
 cmd_update()
 {
+	# parse $args after "submodule ... update".
+	while test $# -ne 0
+	do
+		case "$1" in
+		-q|--quiet)
+			quiet=1
+			;;
+		--)
+			shift
+			break
+			;;
+		-*)
+			usage
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+
 	git ls-files --stage -- "$@" | grep -e '^160000 ' |
 	while read mode sha1 stage path
 	do
@@ -268,6 +333,30 @@ set_name_rev () {
 #
 cmd_status()
 {
+	# parse $args after "submodule ... status".
+	while test $# -ne 0
+	do
+		case "$1" in
+		-q|--quiet)
+			quiet=1
+			;;
+		--cached)
+			cached=1
+			;;
+		--)
+			shift
+			break
+			;;
+		-*)
+			usage
+			;;
+		*)
+			break
+			;;
+		esac
+		shift
+	done
+
 	git ls-files --stage -- "$@" | grep -e '^160000 ' |
 	while read mode sha1 stage path
 	do
@@ -293,20 +382,17 @@ cmd_status()
 	done
 }
 
-while test $# != 0
+# This loop parses the command line arguments to find the
+# subcommand name to dispatch.  Parsing of the subcommand specific
+# options are primarily done by the subcommand implementations.
+# Subcommand specific options such as --branch and --cached are
+# parsed here as well, for backward compatibility.
+
+while test $# != 0 && test -z "$command"
 do
 	case "$1" in
-	add)
-		add=1
-		;;
-	init)
-		init=1
-		;;
-	update)
-		update=1
-		;;
-	status)
-		status=1
+	add | init | update | status)
+		command=$1
 		;;
 	-q|--quiet)
 		quiet=1
@@ -335,30 +421,19 @@ do
 	shift
 done
 
-case "$add,$branch" in
-1,*)
-	;;
-,)
-	;;
-,*)
+# No command word defaults to "status"
+test -n "$command" || command=status
+
+# "-b branch" is accepted only by "add"
+if test -n "$branch" && test "$command" != add
+then
 	usage
-	;;
-esac
-
-case "$add,$init,$update,$status,$cached" in
-1,,,,)
-	cmd_add "$@"
-	;;
-,1,,,)
-	cmd_init "$@"
-	;;
-,,1,,)
-	cmd_update "$@"
-	;;
-,,,*,*)
-	cmd_status "$@"
-	;;
-*)
+fi
+
+# "--cached" is accepted only by "status"
+if test -n "$cached" && test "$command" != status
+then
 	usage
-	;;
-esac
+fi
+
+"cmd_$command" "$@"