[PATCH 1/7] submodule--helper: add valid-label-name

[Stefan Beller <sbeller@google.com>]

We could allow more than just alphanumeric and dash characters
for submodule labels. As a precaution we'll first allow only this
subset and later on we can extend it once we have more experience
with them.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 builtin/submodule--helper.c  | 30 ++++++++++++++++++++++++++-
 t/t7412-submodule--helper.sh | 49 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100755 t/t7412-submodule--helper.sh

diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 7f0941d..d3f4684 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -831,6 +831,33 @@ static int update_clone(int argc, const char **argv, const char *prefix)
 	return 0;
 }
 
+static int submodule_valid_label_name(const char *label)
+{
+	if (!label || !strlen(label))
+		return 0;
+
+	if (!isalnum(*label))
+		return 0;
+
+	while (*label) {
+		if (!(isalnum(*label) ||
+			*label == '-'))
+			return 0;
+		label++;
+	}
+
+	return 1;
+}
+
+static int valid_label_name(int argc, const char **argv, const char *prefix)
+{
+	if (argc == 2 && submodule_valid_label_name(argv[1]))
+		return 0;
+
+	die(_("submodule label must start with an alphanumeric character"
+	      "and must contain alphanumeric characters or dashes only."));
+}
+
 struct cmd_struct {
 	const char *cmd;
 	int (*fn)(int, const char **, const char *);
@@ -843,7 +870,8 @@ static struct cmd_struct commands[] = {
 	{"update-clone", update_clone},
 	{"resolve-relative-url", resolve_relative_url},
 	{"resolve-relative-url-test", resolve_relative_url_test},
-	{"init", module_init}
+	{"init", module_init},
+	{"valid-label-name", valid_label_name}
 };
 
 int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
diff --git a/t/t7412-submodule--helper.sh b/t/t7412-submodule--helper.sh
new file mode 100755
index 0000000..3af315c
--- /dev/null
+++ b/t/t7412-submodule--helper.sh
@@ -0,0 +1,49 @@
+#!/bin/sh
+
+test_description='Basic plumbing support of submodule--helper
+
+This test verifies the submodule--helper plumbing command used to implement
+git-submodule.
+'
+
+. ./test-lib.sh
+
+
+test_expect_success 'valid-label-name tests empty label' '
+	test_must_fail git submodule--helper valid-label-name 2>actual &&
+	test_i18ngrep alphanumeric actual &&
+	test_must_fail git submodule--helper valid-label-name "" 2>actual &&
+	test_i18ngrep alphanumeric actual
+'
+
+test_expect_success 'valid-label-name tests correct label asdf' '
+	git submodule--helper valid-label-name asdf 2>actual &&
+	test_must_be_empty actual
+'
+
+test_expect_success 'valid-label-name tests correct label a' '
+	git submodule--helper valid-label-name a 2>actual &&
+	test_must_be_empty actual
+'
+
+test_expect_success 'valid-label-name tests correct label a-b' '
+	git submodule--helper valid-label-name a-b 2>actual &&
+	test_must_be_empty actual
+'
+
+test_expect_success 'valid-label-name fails with multiple arguments' '
+	test_must_fail git submodule--helper valid-label-name a b 2>actual &&
+	test_i18ngrep alphanumeric actual
+'
+
+test_expect_success 'valid-label-name fails with white spaced arguments' '
+	test_must_fail git submodule--helper valid-label-name "a b" 2>actual &&
+	test_i18ngrep alphanumeric actual
+'
+
+test_expect_success 'valid-label-name fails with utf8 characters' '
+	test_must_fail git submodule--helper valid-label-name ☺ 2>actual &&
+	test_i18ngrep alphanumeric actual
+'
+
+test_done
-- 
2.8.0.35.g58985d9.dirty