unit-name: add new unit_name_build_from_type() helper

The new helper is much like unit_name_build() but expects a UnitType
value instead of a suffix.

src/basic/unit-name.c

@@ -241,25 +241,45 @@ int unit_name_change_suffix(const char *n, const char *suffix, char **ret) {
 }
 
 int unit_name_build(const char *prefix, const char *instance, const char *suffix, char **ret) {
-        char *s;
+        UnitType type;
 
         assert(prefix);
         assert(suffix);
         assert(ret);
 
+        if (isempty(suffix))
+                return -EINVAL;
+        if (suffix[0] != '.')
+                return -EINVAL;
+
+        type = unit_type_from_string(suffix + 1);
+        if (type < 0)
+                return -EINVAL;
+
+        return unit_name_build_from_type(prefix, instance, type, ret);
+}
+
+int unit_name_build_from_type(const char *prefix, const char *instance, UnitType type, char **ret) {
+        const char *ut;
+        char *s;
+
+        assert(prefix);
+        assert(type >= 0);
+        assert(type < _UNIT_TYPE_MAX);
+        assert(ret);
+
         if (!unit_prefix_is_valid(prefix))
                 return -EINVAL;
 
         if (instance && !unit_instance_is_valid(instance))
                 return -EINVAL;
 
-        if (!unit_suffix_is_valid(suffix))
-                return -EINVAL;
+        ut = unit_type_to_string(type);
 
         if (!instance)
-                s = strappend(prefix, suffix);
+                s = strjoin(prefix, ".", ut);
         else
-                s = strjoin(prefix, "@", instance, suffix);
+                s = strjoin(prefix, "@", instance, ".", ut);
         if (!s)
                 return -ENOMEM;
 

src/basic/unit-name.h

@@ -40,6 +40,7 @@ UnitType unit_name_to_type(const char *n) _pure_;
 int unit_name_change_suffix(const char *n, const char *suffix, char **ret);
 
 int unit_name_build(const char *prefix, const char *instance, const char *suffix, char **ret);
+int unit_name_build_from_type(const char *prefix, const char *instance, UnitType, char **ret);
 
 char *unit_name_escape(const char *f);
 int unit_name_unescape(const char *f, char **ret);

src/test/test-unit-name.c

@@ -449,6 +449,26 @@ static void test_unit_name_path_unescape(void) {
         test_unit_name_path_unescape_one("", NULL, -EINVAL);
 }
 
+static void test_unit_name_to_prefix_one(const char *input, int ret, const char *output) {
+        _cleanup_free_ char *k = NULL;
+
+        assert_se(unit_name_to_prefix(input, &k) == ret);
+        assert_se(streq_ptr(k, output));
+}
+
+static void test_unit_name_to_prefix(void) {
+        test_unit_name_to_prefix_one("foobar.service", 0, "foobar");
+        test_unit_name_to_prefix_one("", -EINVAL, NULL);
+        test_unit_name_to_prefix_one("foobar", -EINVAL, NULL);
+        test_unit_name_to_prefix_one(".service", -EINVAL, NULL);
+        test_unit_name_to_prefix_one("quux.quux", -EINVAL, NULL);
+        test_unit_name_to_prefix_one("quux.mount", 0, "quux");
+        test_unit_name_to_prefix_one("quux-quux.mount", 0, "quux-quux");
+        test_unit_name_to_prefix_one("quux@bar.mount", 0, "quux");
+        test_unit_name_to_prefix_one("quux-@.mount", 0, "quux-");
+        test_unit_name_to_prefix_one("@.mount", -EINVAL, NULL);
+}
+
 int main(int argc, char* argv[]) {
         _cleanup_(rm_rf_physical_and_freep) char *runtime_dir = NULL;
         int r, rc = 0;
@@ -482,6 +502,7 @@ int main(int argc, char* argv[]) {
         test_unit_name_escape();
         test_unit_name_template();
         test_unit_name_path_unescape();
+        test_unit_name_to_prefix();
 
         return rc;
 }