From c9552390e76c53cf9b37dee634d4b4de095d2555 Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Tue, 30 Apr 2019 12:56:21 +0400
Subject: [PATCH] Fix stack overflow crash in emoji panel hiding.

A call to hideChildren before setting _hiding to the desired value
could lead through leaveEvent to a recursive call to hideAnimated.
---
 .../SourceFiles/chat_helpers/tabbed_panel.cpp | 22 +++++++++++++------
 .../SourceFiles/chat_helpers/tabbed_panel.h   |  2 +-
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/Telegram/SourceFiles/chat_helpers/tabbed_panel.cpp b/Telegram/SourceFiles/chat_helpers/tabbed_panel.cpp
index a8c56da20..c18992b5c 100644
--- a/Telegram/SourceFiles/chat_helpers/tabbed_panel.cpp
+++ b/Telegram/SourceFiles/chat_helpers/tabbed_panel.cpp
@@ -255,15 +255,21 @@ void TabbedPanel::hideByTimerOrLeave() {
 	hideAnimated();
 }
 
-void TabbedPanel::prepareCache() {
-	if (_a_opacity.animating()) return;
+void TabbedPanel::prepareCacheFor(bool hiding) {
+	if (_a_opacity.animating()) {
+		return;
+	}
 
 	auto showAnimation = base::take(_a_show);
 	auto showAnimationData = base::take(_showAnimation);
+	_hiding = false;
 	showChildren();
+
 	_cache = Ui::GrabWidget(this);
-	_showAnimation = base::take(showAnimationData);
+
 	_a_show = base::take(showAnimation);
+	_showAnimation = base::take(showAnimationData);
+	_hiding = hiding;
 	if (_a_show.animating()) {
 		hideChildren();
 	}
@@ -273,11 +279,13 @@ void TabbedPanel::startOpacityAnimation(bool hiding) {
 	if (_selector && !_selector->isHidden()) {
 		_selector->beforeHiding();
 	}
-	_hiding = false;
-	prepareCache();
-	_hiding = hiding;
+	prepareCacheFor(hiding);
 	hideChildren();
-	_a_opacity.start([this] { opacityAnimationCallback(); }, _hiding ? 1. : 0., _hiding ? 0. : 1., st::emojiPanDuration);
+	_a_opacity.start(
+		[=] { opacityAnimationCallback(); },
+		_hiding ? 1. : 0.,
+		_hiding ? 0. : 1.,
+		st::emojiPanDuration);
 }
 
 void TabbedPanel::startShowAnimation() {
diff --git a/Telegram/SourceFiles/chat_helpers/tabbed_panel.h b/Telegram/SourceFiles/chat_helpers/tabbed_panel.h
index 6f144a3a1..053eae7f4 100644
--- a/Telegram/SourceFiles/chat_helpers/tabbed_panel.h
+++ b/Telegram/SourceFiles/chat_helpers/tabbed_panel.h
@@ -77,7 +77,7 @@ private:
 	QImage grabForAnimation();
 	void startShowAnimation();
 	void startOpacityAnimation(bool hiding);
-	void prepareCache();
+	void prepareCacheFor(bool hiding);
 
 	void opacityAnimationCallback();