transport-helper: add no-private-update capability

Since 664059f (transport-helper: update remote helper namespace,
2013-04-17), a 'push' operation on a remote helper updates the
private ref by default. This is often a good thing, but it can also
be desirable to disable this update to force the next 'pull' to
re-import the pushed revisions.

Allow remote-helpers to disable the automatic update by introducing a new
capability.

Signed-off-by: Matthieu Moy <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: moy

Documentation/gitremote-helpers.txt

@@ -120,6 +120,11 @@ connecting (see the 'connect' command under COMMANDS).
 When choosing between 'push' and 'export', Git prefers 'push'.
 Other frontends may have some other order of preference.
 
+'no-private-update'::
+	When using the 'refspec' capability, git normally updates the
+	private ref on successful push. This update is disabled when
+	the remote-helper declares the capability 'no-private-update'.
+
 
 Capabilities for Fetching
 ^^^^^^^^^^^^^^^^^^^^^^^^^

git-remote-testgit.sh

@@ -38,6 +38,7 @@ do
 			echo "*export-marks $gitmarks"
 		fi
 		test -n "$GIT_REMOTE_TESTGIT_SIGNED_TAGS" && echo "signed-tags"
+		test -n "$GIT_REMOTE_TESTGIT_NO_PRIVATE_UPDATE" && echo "no-private-update"
 		echo
 		;;
 	list)

t/t5801-remote-helpers.sh

@@ -182,6 +182,17 @@ test_expect_success 'push update refs' '
 	)
 '
 
+test_expect_success 'push update refs disabled by no-private-update' '
+	(cd local &&
+	echo more-update >>file &&
+	git commit -a -m more-update &&
+	git rev-parse --verify testgit/origin/heads/update >expect &&
+	GIT_REMOTE_TESTGIT_NO_PRIVATE_UPDATE=t git push origin update &&
+	git rev-parse --verify testgit/origin/heads/update >actual &&
+	test_cmp expect actual
+	)
+'
+
 test_expect_success 'push update refs failure' '
 	(cd local &&
 	git checkout update &&

transport-helper.c

@@ -27,7 +27,8 @@ struct helper_data {
 		push : 1,
 		connect : 1,
 		signed_tags : 1,
-		no_disconnect_req : 1;
+		no_disconnect_req : 1,
+		no_private_update : 1;
 	char *export_marks;
 	char *import_marks;
 	/* These go from remote name (as in "list") to private name */
@@ -205,6 +206,8 @@ static struct child_process *get_helper(struct transport *transport)
 			strbuf_addstr(&arg, "--import-marks=");
 			strbuf_addstr(&arg, capname + strlen("import-marks "));
 			data->import_marks = strbuf_detach(&arg, NULL);
+		} else if (!prefixcmp(capname, "no-private-update")) {
+			data->no_private_update = 1;
 		} else if (mandatory) {
 			die("Unknown mandatory capability %s. This remote "
 			    "helper probably needs newer version of Git.",
@@ -723,7 +726,7 @@ static void push_update_refs_status(struct helper_data *data,
 		if (push_update_ref_status(&buf, &ref, remote_refs))
 			continue;
 
-		if (!data->refspecs)
+		if (!data->refspecs || data->no_private_update)
 			continue;
 
 		/* propagate back the update to the remote namespace */