Attempt to fix crash in story preloading.

Telegram/SourceFiles/data/data_document.cpp

@@ -54,6 +54,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 namespace {
 
 constexpr auto kDefaultCoverThumbnailSize = 100;
+constexpr auto kMaxAllowedPreloadPrefix = 6 * 1024 * 1024;
 
 const auto kLottieStickerDimensions = QSize(
 	kStickerSideSize,
@@ -393,7 +394,7 @@ void DocumentData::setattributes(
 				if (data.is_round_message()) {
 					_additional = std::make_unique<RoundData>();
 				} else if (const auto size = data.vpreload_prefix_size()) {
-					if (size->v > 0) {
+					if (size->v > 0 && size->v < kMaxAllowedPreloadPrefix) {
 						_videoPreloadPrefix = size->v;
 					}
 				}

Telegram/SourceFiles/data/data_stories.h

@@ -217,7 +217,7 @@ public:
 	void registerPolling(not_null<Story*> story, Polling polling);
 	void unregisterPolling(not_null<Story*> story, Polling polling);
 
-	bool registerPolling(FullStoryId id, Polling polling);
+	[[nodiscard]] bool registerPolling(FullStoryId id, Polling polling);
 	void unregisterPolling(FullStoryId id, Polling polling);
 	void requestUserStories(
 		not_null<UserData*> user,

Telegram/SourceFiles/data/data_story.cpp

@@ -23,6 +23,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "main/main_session.h"
 #include "media/streaming/media_streaming_reader.h"
 #include "storage/download_manager_mtproto.h"
+#include "storage/file_download.h" // kMaxFileInMemory
 #include "ui/text/text_utilities.h"
 
 namespace Data {
@@ -574,6 +575,7 @@ void StoryPreload::load() {
 	}
 	_task = std::make_unique<LoadTask>(id(), video, [=](QByteArray data) {
 		if (!data.isEmpty()) {
+			Assert(data.size() < Storage::kMaxFileInMemory);
 			_story->owner().cacheBigFile().putIfEmpty(
 				key,
 				Storage::Cache::Database::TaggedValue(std::move(data), 0));

Telegram/SourceFiles/data/stickers/data_custom_emoji.cpp

@@ -22,6 +22,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "lottie/lottie_frame_generator.h"
 #include "ffmpeg/ffmpeg_frame_generator.h"
 #include "chat_helpers/stickers_lottie.h"
+#include "storage/file_download.h" // kMaxFileInMemory
 #include "ui/widgets/input_fields.h"
 #include "ui/text/text_custom_emoji.h"
 #include "ui/text/text_utilities.h"
@@ -345,7 +346,7 @@ void CustomEmojiLoader::check() {
 	};
 	auto put = [=, key = cacheKey(document)](QByteArray value) {
 		const auto size = value.size();
-		if (size <= Storage::Cache::Database::Settings().maxDataSize) {
+		if (size <= Storage::kMaxFileInMemory) {
 			document->owner().cacheBigFile().put(key, std::move(value));
 		} else {
 			LOG(("Data Error: Cached emoji size too big: %1.").arg(size));

Telegram/SourceFiles/info/stories/info_stories_provider.cpp

@@ -283,9 +283,10 @@ BaseLayout *Provider::getLayout(
 		if (auto layout = createLayout(id, delegate)) {
 			layout->initDimensions();
 			it = _layouts.emplace(id, std::move(layout)).first;
-			_peer->owner().stories().registerPolling(
+			const auto ok = _peer->owner().stories().registerPolling(
 				{ _peer->id, id },
 				Data::Stories::Polling::Chat);
+			Assert(ok);
 		} else {
 			return nullptr;
 		}