From a3f19c073bf642e9ce1449056d5dbba9767c8428 Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Thu, 20 Feb 2020 13:37:00 +0400
Subject: [PATCH] Fix 'reading' of an empty history.

---
 Telegram/SourceFiles/data/data_histories.cpp | 6 +++++-
 Telegram/SourceFiles/history/history.cpp     | 4 ++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/Telegram/SourceFiles/data/data_histories.cpp b/Telegram/SourceFiles/data/data_histories.cpp
index c3e945da5..f3516d2ca 100644
--- a/Telegram/SourceFiles/data/data_histories.cpp
+++ b/Telegram/SourceFiles/data/data_histories.cpp
@@ -131,6 +131,8 @@ void Histories::readInboxTill(
 		not_null<History*> history,
 		MsgId tillId,
 		bool force) {
+	Expects(IsServerMsgId(tillId) || (!tillId && !force));
+
 	if (!history->readInboxTillNeedsRequest(tillId) && !force) {
 		return;
 	} else if (!force) {
@@ -202,7 +204,9 @@ void Histories::sendReadRequests() {
 	const auto now = crl::now();
 	auto next = std::optional<crl::time>();
 	for (auto &[history, state] : _states) {
-		if (state.readTill && state.readWhen <= now) {
+		if (!state.readTill) {
+			continue;
+		} else if (state.readWhen <= now) {
 			sendReadRequest(history, state);
 		} else if (!next || *next > state.readWhen) {
 			next = state.readWhen;
diff --git a/Telegram/SourceFiles/history/history.cpp b/Telegram/SourceFiles/history/history.cpp
index c225d8cb8..d0c953fe3 100644
--- a/Telegram/SourceFiles/history/history.cpp
+++ b/Telegram/SourceFiles/history/history.cpp
@@ -1615,13 +1615,13 @@ void History::calculateFirstUnreadMessage() {
 }
 
 bool History::readInboxTillNeedsRequest(MsgId tillId) {
-	Expects(IsServerMsgId(tillId));
+	Expects(!tillId || IsServerMsgId(tillId));
 
 	readClientSideMessages();
 	if (unreadMark()) {
 		session().api().changeDialogUnreadMark(this, false);
 	}
-	return (_inboxReadBefore.value_or(1) <= tillId);
+	return IsServerMsgId(tillId) && (_inboxReadBefore.value_or(1) <= tillId);
 }
 
 void History::readClientSideMessages() {