From 23c8ef2f63720f0962e27238066f4cb904c94b8c Mon Sep 17 00:00:00 2001
From: levlam <levlam@telegram.org>
Date: Thu, 23 Mar 2023 16:53:11 +0300
Subject: [PATCH] Return error 404 from addApplicationChangelog if nothing was
 added.

---
 td/generate/scheme/td_api.tl   |  2 +-
 td/telegram/Application.cpp    |  6 +++++-
 td/telegram/UpdatesManager.cpp | 19 +++++++++++++++++++
 td/telegram/UpdatesManager.h   |  5 ++++-
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/td/generate/scheme/td_api.tl b/td/generate/scheme/td_api.tl
index cf73ab456..04bcc7837 100644
--- a/td/generate/scheme/td_api.tl
+++ b/td/generate/scheme/td_api.tl
@@ -8215,7 +8215,7 @@ getDeepLinkInfo link:string = DeepLinkInfo;
 //@description Returns application config, provided by the server. Can be called before authorization
 getApplicationConfig = JsonValue;
 
-//@description Adds server-provided application changelog as messages to the chat 777000 (Telegram); for official applications only @previous_application_version The previous application version
+//@description Adds server-provided application changelog as messages to the chat 777000 (Telegram); for official applications only. Returns a 404 error if nothing changed @previous_application_version The previous application version
 addApplicationChangelog previous_application_version:string = Ok;
 
 //@description Saves application log event on the server. Can be called before authorization @type Event type @chat_id Optional chat identifier, associated with the event @data The log event data
diff --git a/td/telegram/Application.cpp b/td/telegram/Application.cpp
index c3217ca8f..dfbf71bbe 100644
--- a/td/telegram/Application.cpp
+++ b/td/telegram/Application.cpp
@@ -95,7 +95,11 @@ class GetAppChangelogQuery final : public Td::ResultHandler {
       return on_error(result_ptr.move_as_error());
     }
 
-    td_->updates_manager_->on_get_updates(result_ptr.move_as_ok(), std::move(promise_));
+    auto ptr = result_ptr.move_as_ok();
+    if (td_->updates_manager_->are_empty_updates(ptr.get())) {
+      return promise_.set_error(Status::Error(404, "Changelog not found"));
+    }
+    td_->updates_manager_->on_get_updates(std::move(ptr), std::move(promise_));
   }
 
   void on_error(Status status) final {
diff --git a/td/telegram/UpdatesManager.cpp b/td/telegram/UpdatesManager.cpp
index 8ac77bb4c..a7dbb99e5 100644
--- a/td/telegram/UpdatesManager.cpp
+++ b/td/telegram/UpdatesManager.cpp
@@ -1174,6 +1174,25 @@ vector<tl_object_ptr<telegram_api::Update>> *UpdatesManager::get_updates(telegra
       get_updates(static_cast<const telegram_api::Updates *>(updates_ptr)));
 }
 
+bool UpdatesManager::are_empty_updates(const telegram_api::Updates *updates_ptr) {
+  switch (updates_ptr->get_id()) {
+    case telegram_api::updatesTooLong::ID:
+    case telegram_api::updateShortSentMessage::ID:
+      return true;
+    case telegram_api::updateShortMessage::ID:
+    case telegram_api::updateShortChatMessage::ID:
+    case telegram_api::updateShort::ID:
+      return false;
+    case telegram_api::updatesCombined::ID:
+      return static_cast<const telegram_api::updatesCombined *>(updates_ptr)->updates_.empty();
+    case telegram_api::updates::ID:
+      return static_cast<const telegram_api::updates *>(updates_ptr)->updates_.empty();
+    default:
+      UNREACHABLE();
+      return true;
+  }
+}
+
 vector<UserId> UpdatesManager::extract_group_invite_privacy_forbidden_updates(
     tl_object_ptr<telegram_api::Updates> &updates_ptr) {
   auto updates = get_updates(updates_ptr.get());
diff --git a/td/telegram/UpdatesManager.h b/td/telegram/UpdatesManager.h
index 1268beeb7..6510fde6d 100644
--- a/td/telegram/UpdatesManager.h
+++ b/td/telegram/UpdatesManager.h
@@ -103,7 +103,10 @@ class UpdatesManager final : public Actor {
   void add_pending_pts_update(tl_object_ptr<telegram_api::Update> &&update, int32 new_pts, int32 pts_count,
                               double receive_time, Promise<Unit> &&promise, const char *source);
 
-  vector<UserId> extract_group_invite_privacy_forbidden_updates(tl_object_ptr<telegram_api::Updates> &updates_ptr);
+  static bool are_empty_updates(const telegram_api::Updates *updates_ptr);
+
+  static vector<UserId> extract_group_invite_privacy_forbidden_updates(
+      tl_object_ptr<telegram_api::Updates> &updates_ptr);
 
   static FlatHashSet<int64> get_sent_messages_random_ids(const telegram_api::Updates *updates_ptr);