Fix a long-standing bug where the user directory would return 1 more row than requested. (#14631)

4 files changed, 10 insertions, 3 deletions

diff --git a/changelog.d/14631.bugfix b/changelog.d/14631.bugfix
new file mode 100644

index 0000000000..c5376bab9f
--- /dev/null
+++ b/changelog.d/14631.bugfix
@@ -0,0 +1 @@
+Fix a long-standing bug where the user directory would return 1 more row than requested.
\ No newline at end of file
diff --git a/synapse/rest/client/user_directory.py b/synapse/rest/client/user_directory.py

index 116c982ce6..4670fad608 100644
--- a/synapse/rest/client/user_directory.py
+++ b/synapse/rest/client/user_directory.py
@@ -63,8 +63,8 @@ class UserDirectorySearchRestServlet(RestServlet):
 
         body = parse_json_object_from_request(request)
 
-        limit = body.get("limit", 10)
-        limit = min(limit, 50)
+        limit = int(body.get("limit", 10))
+        limit = max(min(limit, 50), 0)
 
         try:
             search_term = body["search_term"]
diff --git a/synapse/storage/databases/main/user_directory.py b/synapse/storage/databases/main/user_directory.py

index 044435deab..af9952f513 100644
--- a/synapse/storage/databases/main/user_directory.py
+++ b/synapse/storage/databases/main/user_directory.py
@@ -886,7 +886,7 @@ class UserDirectoryStore(UserDirectoryBackgroundUpdateStore):
 
         limited = len(results) > limit
 
-        return {"limited": limited, "results": results}
+        return {"limited": limited, "results": results[0:limit]}
 
 
 def _parse_query_sqlite(search_term: str) -> str:
diff --git a/tests/storage/test_user_directory.py b/tests/storage/test_user_directory.py

index 5b60cf5285..88c7d5fec0 100644
--- a/tests/storage/test_user_directory.py
+++ b/tests/storage/test_user_directory.py
@@ -449,6 +449,12 @@ class UserDirectoryStoreTestCase(HomeserverTestCase):
         )
 
     @override_config({"user_directory": {"search_all_users": True}})
+    def test_search_user_limit_correct(self) -> None:
+        r = self.get_success(self.store.search_user_dir(ALICE, "bob", 1))
+        self.assertTrue(r["limited"])
+        self.assertEqual(1, len(r["results"]))
+
+    @override_config({"user_directory": {"search_all_users": True}})
     def test_search_user_dir_stop_words(self) -> None:
         """Tests that a user can look up another user by searching for the start if its
         display name even if that name happens to be a common English word that would