From 14dbd1c92dfea5bb3b2d713d27170e1270a7c779 Mon Sep 17 00:00:00 2001
From: arvidn <arvid@cs.umu.se>
Date: Sun, 7 May 2017 11:01:42 -0400
Subject: [PATCH] fix race condition in disk I/O storage class

---
 ChangeLog                      | 1 +
 include/libtorrent/storage.hpp | 1 +
 src/storage.cpp                | 9 +++++++--
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 12ac76686..ba72f7f9f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,4 @@
+	* fix race condition in disk I/O storage class
 	* fix http connection timeout on multi-homed hosts
 	* removed depdendency on boost::uintptr_t for better compatibility
 	* fix memory leak in the disk cache
diff --git a/include/libtorrent/storage.hpp b/include/libtorrent/storage.hpp
index da894d7f9..844071d28 100644
--- a/include/libtorrent/storage.hpp
+++ b/include/libtorrent/storage.hpp
@@ -476,6 +476,7 @@ namespace libtorrent
 		// whose bit is 0, we set the file size, to make the file allocated
 		// on disk (in full allocation mode) and just sparsely allocated in
 		// case of sparse allocation mode
+		mutable mutex m_file_created_mutex;
 		mutable bitfield m_file_created;
 
 		bool m_allocate_files;
diff --git a/src/storage.cpp b/src/storage.cpp
index a22c70e5f..9c0b7b1ce 100644
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -524,7 +524,10 @@ namespace libtorrent
 			m_allocate_files = false;
 #endif
 
-		m_file_created.resize(files().num_files(), false);
+		{
+			mutex::scoped_lock l(m_file_created_mutex);
+			m_file_created.resize(files().num_files(), false);
+		}
 
 		// first, create all missing directories
 		std::string last_path;
@@ -1494,6 +1497,7 @@ namespace libtorrent
 
 		if (m_allocate_files && (mode & file::rw_mask) != file::read_only)
 		{
+			mutex::scoped_lock l(m_file_created_mutex);
 			if (m_file_created.size() != files().num_files())
 				m_file_created.resize(files().num_files(), false);
 
@@ -1504,10 +1508,11 @@ namespace libtorrent
 			// the file right away, to allocate it on the filesystem.
 			if (m_file_created[file] == false)
 			{
+				m_file_created.set_bit(file);
+				l.unlock();
 				error_code e;
 				boost::int64_t const size = files().file_size(file);
 				h->set_size(size, e);
-				m_file_created.set_bit(file);
 				if (e)
 				{
 					ec.ec = e;