unit-name: rework unit_name_replace_instance function()

https://bugzilla.redhat.com/show_bug.cgi?id=855863

2 files changed, 38 insertions, 21 deletions

diff --git a/src/shared/unit-name.c b/src/shared/unit-name.c
index 7193718792..d6391228f2 100644
--- a/src/shared/unit-name.c
+++ b/src/shared/unit-name.c
@@ -357,36 +357,29 @@ bool unit_name_is_instance(const char *n) {
 char *unit_name_replace_instance(const char *f, const char *i) {
         const char *p, *e;
         char *r, *k;
-        size_t a;
+        size_t a, b;
 
         assert(f);
 
         p = strchr(f, '@');
-        assert_se(e = strrchr(f, '.'));
-
-        a = p - f;
-
-        if (p) {
-                size_t b;
-
-                b = strlen(i);
-
-                r = new(char, a + 1 + b + strlen(e) + 1);
-                if (!r)
-                        return NULL;
+        if (!p)
+                return strdup(f);
 
-                k = mempcpy(r, f, a + 1);
-                k = mempcpy(k, i, b);
-        } else {
+        e = strrchr(f, '.');
+        if (!e)
+                assert_se(e = strchr(f, 0));
 
-                r = new(char, a + strlen(e) + 1);
-                if (!r)
-                        return NULL;
+        a = p - f;
+        b = strlen(i);
 
-                k = mempcpy(r, f, a);
-        }
+        r = new(char, a + 1 + b + strlen(e) + 1);
+        if (!r)
+                return NULL;
 
+        k = mempcpy(r, f, a + 1);
+        k = mempcpy(k, i, b);
         strcpy(k, e);
+
         return r;
 }
 
diff --git a/src/test/test-unit-name.c b/src/test/test-unit-name.c
index 392e358ac2..cf434558c3 100644
--- a/src/test/test-unit-name.c
+++ b/src/test/test-unit-name.c
@@ -29,6 +29,30 @@
 int main(int argc, char* argv[]) {
         char *t, *k;
 
+        t = unit_name_replace_instance("foo@.service", "waldo");
+        puts(t);
+        free(t);
+
+        t = unit_name_replace_instance("foo@xyz.service", "waldo");
+        puts(t);
+        free(t);
+
+        t = unit_name_replace_instance("xyz", "waldo");
+        puts(t);
+        free(t);
+
+        t = unit_name_replace_instance("", "waldo");
+        puts(t);
+        free(t);
+
+        t = unit_name_replace_instance("", "");
+        puts(t);
+        free(t);
+
+        t = unit_name_replace_instance("foo.service", "waldo");
+        puts(t);
+        free(t);
+
         t = unit_name_from_path("/waldo", ".mount");
         puts(t);
         k = unit_name_to_path(t);