From 8a8e101cd01ea5d0e2f2e35aa6ef06843864ac57 Mon Sep 17 00:00:00 2001
From: John Preston <johnprestonmail@gmail.com>
Date: Sat, 15 Apr 2017 20:35:13 +0300
Subject: [PATCH] Fix crash in file downloader destruction.

Regression was introduced in 835b1801bc.

We need to destroy all FileLoader instances before destroying the
Downloader instance, because they hold pointers to it and call its
methods in destructor if they need to cancel some MTP requests.
---
 Telegram/SourceFiles/storage/file_download.cpp | 7 +++++++
 Telegram/SourceFiles/storage/file_download.h   | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/Telegram/SourceFiles/storage/file_download.cpp b/Telegram/SourceFiles/storage/file_download.cpp
index 9f49cc8c8..ae7993da4 100644
--- a/Telegram/SourceFiles/storage/file_download.cpp
+++ b/Telegram/SourceFiles/storage/file_download.cpp
@@ -69,6 +69,13 @@ int Downloader::chooseDcIndexForRequest(MTP::DcId dcId) const {
 	return result;
 }
 
+Downloader::~Downloader() {
+	// The file loaders have pointer to downloader and they cancel
+	// requests in destructor where they use that pointer, so all
+	// of them need to be destroyed before any internal state of Downloader.
+	_delayedDestroyedLoaders.clear();
+}
+
 } // namespace Storage
 
 namespace {
diff --git a/Telegram/SourceFiles/storage/file_download.h b/Telegram/SourceFiles/storage/file_download.h
index 5bc1a314f..62631d65a 100644
--- a/Telegram/SourceFiles/storage/file_download.h
+++ b/Telegram/SourceFiles/storage/file_download.h
@@ -43,6 +43,8 @@ public:
 	void requestedAmountIncrement(MTP::DcId dcId, int index, int amount);
 	int chooseDcIndexForRequest(MTP::DcId dcId) const;
 
+	~Downloader();
+
 private:
 	base::Observable<void> _taskFinishedObservable;
 	int _priority = 1;