[PATCH 01/12] Generate unique ID for submodules created using "git submodule add"

[Peter Collingbourne <peter@pcc.me.uk>]

This patch causes "git submodule add" to generate a unique ID for
the submodule which is used as its name.  The ID is generated by
computing the SHA1 hash of the pid, date and initial path.

The purpose of this patch is to avoid name conflicts which may
arise due to the ability to rename submodules.

Signed-off-by: Peter Collingbourne <peter@pcc.me.uk>
---
 Documentation/git-submodule.txt |    8 +++++++-
 git-submodule.sh                |   28 ++++++++++++++++++++++++++--
 t/t7403-submodule-sync.sh       |    2 +-
 t/t7406-submodule-update.sh     |    6 +++---
 t/t7407-submodule-foreach.sh    |   14 +++++++-------
 5 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
index 2502531..1bf78b6 100644
--- a/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git submodule' [--quiet] add [-b branch]
-	      [--reference <repository>] [--] <repository> [<path>]
+	      [--reference <repository>] [-n <name>] [--] <repository> [<path>]
 'git submodule' [--quiet] status [--cached] [--recursive] [--] [<path>...]
 'git submodule' [--quiet] init [--] [<path>...]
 'git submodule' [--quiet] update [--init] [-N|--no-fetch] [--rebase]
@@ -199,6 +199,12 @@ OPTIONS
 	(the default). This limit only applies to modified submodules. The
 	size is always limited to 1 for added/deleted/typechanged submodules.
 
+-n <name>::
+--name <name>::
+	This option is only valid for the add command.
+	Name of the new submodule.  By default, a unique identifier
+	is generated.
+
 -N::
 --no-fetch::
 	This option is only valid for the update command.
diff --git a/git-submodule.sh b/git-submodule.sh
index 2dd372a..f05ff4e 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -114,6 +114,20 @@ module_clone()
 }
 
 #
+# Generate a unique identifier.  Used to name a submodule.
+#
+gen_uid()
+{
+	path="$1"
+
+	(
+	 echo "$path"
+	 echo $$
+	 date
+	) | git hash-object --stdin
+}
+
+#
 # Add a new submodule to the working tree, .gitmodules and the index
 #
 # $@ = repo path
@@ -131,6 +145,11 @@ cmd_add()
 			branch=$2
 			shift
 			;;
+		-n | --name)
+			case "$2" in '') usage ;; esac
+			name=$2
+			shift
+			;;
 		-q|--quiet)
 			GIT_QUIET=1
 			;;
@@ -235,8 +254,13 @@ cmd_add()
 	git add "$path" ||
 	die "Failed to add submodule '$path'"
 
-	git config -f .gitmodules submodule."$path".path "$path" &&
-	git config -f .gitmodules submodule."$path".url "$repo" &&
+	if test -z "$name"
+	then
+		name=$(gen_uid "$path")
+	fi
+
+	git config -f .gitmodules submodule."$name".path "$path" &&
+	git config -f .gitmodules submodule."$name".url "$repo" &&
 	git add .gitmodules ||
 	die "Failed to register submodule '$path'"
 }
diff --git a/t/t7403-submodule-sync.sh b/t/t7403-submodule-sync.sh
index 7538756..f2c66f8 100755
--- a/t/t7403-submodule-sync.sh
+++ b/t/t7403-submodule-sync.sh
@@ -18,7 +18,7 @@ test_expect_success setup '
 	git clone . super &&
 	git clone super submodule &&
 	(cd super &&
-	 git submodule add ../submodule submodule &&
+	 git submodule add -n submodule ../submodule submodule &&
 	 test_tick &&
 	 git commit -m "submodule"
 	) &&
diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index 1382a8e..5bcac8f 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -31,7 +31,7 @@ test_expect_success 'setup a submodule tree' '
 	git clone super rebasing &&
 	git clone super merging &&
 	(cd super &&
-	 git submodule add ../submodule submodule &&
+	 git submodule add -n submodule ../submodule submodule &&
 	 test_tick &&
 	 git commit -m "submodule" &&
 	 git submodule init submodule
@@ -49,12 +49,12 @@ test_expect_success 'setup a submodule tree' '
 	 git commit -m "submodule update"
 	) &&
 	(cd super &&
-	 git submodule add ../rebasing rebasing &&
+	 git submodule add -n rebasing ../rebasing rebasing &&
 	 test_tick &&
 	 git commit -m "rebasing"
 	) &&
 	(cd super &&
-	 git submodule add ../merging merging &&
+	 git submodule add -n merging ../merging merging &&
 	 test_tick &&
 	 git commit -m "rebasing"
 	)
diff --git a/t/t7407-submodule-foreach.sh b/t/t7407-submodule-foreach.sh
index 2a52775..a0390dd 100755
--- a/t/t7407-submodule-foreach.sh
+++ b/t/t7407-submodule-foreach.sh
@@ -21,9 +21,9 @@ test_expect_success 'setup a submodule tree' '
 	git clone super submodule &&
 	(
 		cd super &&
-		git submodule add ../submodule sub1 &&
-		git submodule add ../submodule sub2 &&
-		git submodule add ../submodule sub3 &&
+		git submodule add -n sub1 ../submodule sub1 &&
+		git submodule add -n sub2 ../submodule sub2 &&
+		git submodule add -n sub3 ../submodule sub3 &&
 		git config -f .gitmodules --rename-section \
 			submodule.sub1 submodule.foo1 &&
 		git config -f .gitmodules --rename-section \
@@ -82,28 +82,28 @@ test_expect_success 'setup nested submodules' '
 	git clone submodule nested3 &&
 	(
 		cd nested3 &&
-		git submodule add ../submodule submodule &&
+		git submodule add -n submodule ../submodule submodule &&
 		test_tick &&
 		git commit -m "submodule" &&
 		git submodule init submodule
 	) &&
 	(
 		cd nested2 &&
-		git submodule add ../nested3 nested3 &&
+		git submodule add -n nested3 ../nested3 nested3 &&
 		test_tick &&
 		git commit -m "nested3" &&
 		git submodule init nested3
 	) &&
 	(
 		cd nested1 &&
-		git submodule add ../nested2 nested2 &&
+		git submodule add -n nested2 ../nested2 nested2 &&
 		test_tick &&
 		git commit -m "nested2" &&
 		git submodule init nested2
 	) &&
 	(
 		cd super &&
-		git submodule add ../nested1 nested1 &&
+		git submodule add -n nested1 ../nested1 nested1 &&
 		test_tick &&
 		git commit -m "nested1" &&
 		git submodule init nested1
-- 
1.6.5