Merge branch 'jk/deny-push-to-current'

* jk/deny-push-to-current:
  receive-pack: detect push to current branch of non-bare repo
  t5516: refactor oddball tests

Documentation/config.txt

@@ -1198,6 +1198,15 @@ receive.denyNonFastForwards::
 	even if that push is forced. This configuration variable is
 	set when initializing a shared repository.
 
+receive.denyCurrentBranch::
+	If set to true or "refuse", receive-pack will deny a ref update
+	to the currently checked out branch of a non-bare repository.
+	Such a push is potentially dangerous because it brings the HEAD
+	out of sync with the index and working tree. If set to "warn",
+	print a warning of such a push to stderr, but allow the push to
+	proceed. If set to false or "ignore", allow such pushes with no
+	message. Defaults to "warn".
+
 transfer.unpackLimit::
 	When `fetch.unpackLimit` or `receive.unpackLimit` are
 	not set, the value of this variable is used instead.

builtin-receive-pack.c

@@ -11,8 +11,15 @@
 
 static const char receive_pack_usage[] = "git-receive-pack <git-dir>";
 
+enum deny_action {
+	DENY_IGNORE,
+	DENY_WARN,
+	DENY_REFUSE,
+};
+
 static int deny_deletes = 0;
 static int deny_non_fast_forwards = 0;
+static enum deny_action deny_current_branch = DENY_WARN;
 static int receive_fsck_objects;
 static int receive_unpack_limit = -1;
 static int transfer_unpack_limit = -1;
@@ -22,6 +29,21 @@ static int report_status;
 static char capabilities[] = " report-status delete-refs ";
 static int capabilities_sent;
 
+static enum deny_action parse_deny_action(const char *var, const char *value)
+{
+	if (value) {
+		if (!strcasecmp(value, "ignore"))
+			return DENY_IGNORE;
+		if (!strcasecmp(value, "warn"))
+			return DENY_WARN;
+		if (!strcasecmp(value, "refuse"))
+			return DENY_REFUSE;
+	}
+	if (git_config_bool(var, value))
+		return DENY_REFUSE;
+	return DENY_IGNORE;
+}
+
 static int receive_pack_config(const char *var, const char *value, void *cb)
 {
 	if (strcmp(var, "receive.denydeletes") == 0) {
@@ -49,6 +71,11 @@ static int receive_pack_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (!strcmp(var, "receive.denycurrentbranch")) {
+		deny_current_branch = parse_deny_action(var, value);
+		return 0;
+	}
+
 	return git_default_config(var, value, cb);
 }
 
@@ -173,6 +200,20 @@ static int run_update_hook(struct command *cmd)
 	return hook_status(run_command(&proc), update_hook);
 }
 
+static int is_ref_checked_out(const char *ref)
+{
+	unsigned char sha1[20];
+	const char *head;
+
+	if (is_bare_repository())
+		return 0;
+
+	head = resolve_ref("HEAD", sha1, 0, NULL);
+	if (!head)
+		return 0;
+	return !strcmp(head, ref);
+}
+
 static const char *update(struct command *cmd)
 {
 	const char *name = cmd->ref_name;
@@ -186,6 +227,24 @@ static const char *update(struct command *cmd)
 		return "funny refname";
 	}
 
+	switch (deny_current_branch) {
+	case DENY_IGNORE:
+		break;
+	case DENY_WARN:
+		if (!is_ref_checked_out(name))
+			break;
+		warning("updating the currently checked out branch; this may"
+			" cause confusion,\n"
+			"as the index and working tree do not reflect changes"
+			" that are now in HEAD.");
+		break;
+	case DENY_REFUSE:
+		if (!is_ref_checked_out(name))
+			break;
+		error("refusing to update checked out branch: %s", name);
+		return "branch is currently checked out";
+	}
+
 	if (!is_null_sha1(new_sha1) && !has_sha1_file(new_sha1)) {
 		error("unpack should have generated %s, "
 		      "but I can't find it!", sha1_to_hex(new_sha1));

t/t5516-fetch-push.sh

@@ -39,6 +39,11 @@ mk_test () {
 	)
 }
 
+mk_child() {
+	rm -rf "$1" &&
+	git clone testrepo "$1"
+}
+
 check_push_result () {
 	(
 		cd testrepo &&
@@ -425,13 +430,10 @@ test_expect_success 'push with dry-run' '
 
 test_expect_success 'push updates local refs' '
 
-	rm -rf parent child &&
+	mk_test heads/master &&
-	mkdir parent &&
+	mk_child child &&
-	(cd parent && git init &&
-		echo one >foo && git add foo && git commit -m one) &&
-	git clone parent child &&
 	(cd child &&
-		echo two >foo && git commit -a -m two &&
+		git pull .. master &&
 		git push &&
 	test $(git rev-parse master) = $(git rev-parse remotes/origin/master))
 
@@ -439,15 +441,10 @@ test_expect_success 'push updates local refs' '
 
 test_expect_success 'push updates up-to-date local refs' '
 
-	rm -rf parent child &&
+	mk_test heads/master &&
-	mkdir parent &&
+	mk_child child1 &&
-	(cd parent && git init &&
+	mk_child child2 &&
-		echo one >foo && git add foo && git commit -m one) &&
+	(cd child1 && git pull .. master && git push) &&
-	git clone parent child1 &&
-	git clone parent child2 &&
-	(cd child1 &&
-		echo two >foo && git commit -a -m two &&
-		git push) &&
 	(cd child2 &&
 		git pull ../child1 master &&
 		git push &&
@@ -457,11 +454,8 @@ test_expect_success 'push updates up-to-date local refs' '
 
 test_expect_success 'push preserves up-to-date packed refs' '
 
-	rm -rf parent child &&
+	mk_test heads/master &&
-	mkdir parent &&
+	mk_child child &&
-	(cd parent && git init &&
-		echo one >foo && git add foo && git commit -m one) &&
-	git clone parent child &&
 	(cd child &&
 		git push &&
 	! test -f .git/refs/remotes/origin/master)
@@ -470,15 +464,13 @@ test_expect_success 'push preserves up-to-date packed refs' '
 
 test_expect_success 'push does not update local refs on failure' '
 
-	rm -rf parent child &&
+	mk_test heads/master &&
-	mkdir parent &&
+	mk_child child &&
-	(cd parent && git init &&
+	mkdir testrepo/.git/hooks &&
-		echo one >foo && git add foo && git commit -m one &&
+	echo exit 1 >testrepo/.git/hooks/pre-receive &&
-		echo exit 1 >.git/hooks/pre-receive &&
+	chmod +x testrepo/.git/hooks/pre-receive &&
-		chmod +x .git/hooks/pre-receive) &&
-	git clone parent child &&
 	(cd child &&
-		echo two >foo && git commit -a -m two &&
+		git pull .. master
 		test_must_fail git push &&
 		test $(git rev-parse master) != \
 			$(git rev-parse remotes/origin/master))
@@ -487,11 +479,48 @@ test_expect_success 'push does not update local refs on failure' '
 
 test_expect_success 'allow deleting an invalid remote ref' '
 
-	pwd &&
+	mk_test heads/master &&
 	rm -f testrepo/.git/objects/??/* &&
 	git push testrepo :refs/heads/master &&
 	(cd testrepo && test_must_fail git rev-parse --verify refs/heads/master)
 
 '
 
+test_expect_success 'warn on push to HEAD of non-bare repository' '
+	mk_test heads/master
+	(cd testrepo &&
+		git checkout master &&
+		git config receive.denyCurrentBranch warn) &&
+	git push testrepo master 2>stderr &&
+	grep "warning.*this may cause confusion" stderr
+'
+
+test_expect_success 'deny push to HEAD of non-bare repository' '
+	mk_test heads/master
+	(cd testrepo &&
+		git checkout master &&
+		git config receive.denyCurrentBranch true) &&
+	test_must_fail git push testrepo master
+'
+
+test_expect_success 'allow push to HEAD of bare repository (bare)' '
+	mk_test heads/master
+	(cd testrepo &&
+		git checkout master &&
+		git config receive.denyCurrentBranch true &&
+		git config core.bare true) &&
+	git push testrepo master 2>stderr &&
+	! grep "warning.*this may cause confusion" stderr
+'
+
+test_expect_success 'allow push to HEAD of non-bare repository (config)' '
+	mk_test heads/master
+	(cd testrepo &&
+		git checkout master &&
+		git config receive.denyCurrentBranch false
+	) &&
+	git push testrepo master 2>stderr &&
+	! grep "warning.*this may cause confusion" stderr
+'
+
 test_done