From cf3ee14a9d55b477772cc625662dca18c43dd44b Mon Sep 17 00:00:00 2001
From: Liryna <adrienj@google.com>
Date: Sun, 13 Feb 2022 18:15:16 -0500
Subject: [PATCH] MemFS - Replace std::mutex by std::shared_mutex

---
 samples/dokan_memfs/filenode.cpp         | 18 +++++++++---------
 samples/dokan_memfs/filenode.h           |  8 ++++----
 samples/dokan_memfs/memfs_operations.cpp |  4 ++--
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/samples/dokan_memfs/filenode.cpp b/samples/dokan_memfs/filenode.cpp
index 748b94deb..99d51e1d5 100644
--- a/samples/dokan_memfs/filenode.cpp
+++ b/samples/dokan_memfs/filenode.cpp
@@ -44,7 +44,7 @@ filenode::filenode(const std::wstring& filename, bool is_directory,
 }
 
 DWORD filenode::read(LPVOID buffer, DWORD bufferlength, LONGLONG offset) {
-  std::lock_guard<std::mutex> lock(_data_mutex);
+  std::shared_lock lock(_data_mutex);
   if (static_cast<size_t>(offset + bufferlength) > _data.size())
     bufferlength = (_data.size() > static_cast<size_t>(offset))
                        ? static_cast<DWORD>(_data.size() - offset)
@@ -60,7 +60,7 @@ DWORD filenode::write(LPCVOID buffer, DWORD number_of_bytes_to_write,
                       LONGLONG offset) {
   if (!number_of_bytes_to_write) return 0;
 
-  std::lock_guard<std::mutex> lock(_data_mutex);
+  std::unique_lock lock(_data_mutex);
   if (static_cast<size_t>(offset + number_of_bytes_to_write) > _data.size())
     _data.resize(static_cast<size_t>(offset + number_of_bytes_to_write));
 
@@ -71,38 +71,38 @@ DWORD filenode::write(LPCVOID buffer, DWORD number_of_bytes_to_write,
 }
 
 const LONGLONG filenode::get_filesize() {
-  std::lock_guard<std::mutex> lock(_data_mutex);
+  std::shared_lock lock(_data_mutex);
   return static_cast<LONGLONG>(_data.size());
 }
 
 void filenode::set_endoffile(const LONGLONG& byte_offset) {
-  std::lock_guard<std::mutex> lock(_data_mutex);
+  std::unique_lock lock(_data_mutex);
   _data.resize(static_cast<size_t>(byte_offset));
 }
 
 const std::wstring filenode::get_filename() {
-  std::lock_guard<std::mutex> lock(_fileName_mutex);
+  std::shared_lock lock(_fileName_mutex);
   return _fileName;
 }
 
 void filenode::set_filename(const std::wstring& f) {
-  std::lock_guard<std::mutex> lock(_fileName_mutex);
+  std::unique_lock lock(_fileName_mutex);
   _fileName = f;
 }
 
 void filenode::add_stream(const std::shared_ptr<filenode>& stream) {
-  std::lock_guard<std::mutex> lock(_data_mutex);
+  std::unique_lock lock(_data_mutex);
   _streams[stream->get_filename()] = stream;
 }
 
 void filenode::remove_stream(const std::shared_ptr<filenode>& stream) {
-  std::lock_guard<std::mutex> lock(_data_mutex);
+  std::unique_lock lock(_data_mutex);
   _streams.erase(stream->get_filename());
 }
 
 std::unordered_map<std::wstring, std::shared_ptr<filenode> >
 filenode::get_streams() {
-  std::lock_guard<std::mutex> lock(_data_mutex);
+  std::shared_lock lock(_data_mutex);
   return _streams;
 }
 }  // namespace memfs
\ No newline at end of file
diff --git a/samples/dokan_memfs/filenode.h b/samples/dokan_memfs/filenode.h
index afef17f2e..63b32389d 100644
--- a/samples/dokan_memfs/filenode.h
+++ b/samples/dokan_memfs/filenode.h
@@ -36,7 +36,7 @@ THE SOFTWARE.
 #include <WinBase.h>
 #include <atomic>
 #include <filesystem>
-#include <mutex>
+#include <shared_mutex>
 #include <sstream>
 #include <string>
 #include <unordered_map>
@@ -44,7 +44,7 @@ THE SOFTWARE.
 namespace memfs {
 
 // Safe class wrapping a Win32 Security Descriptor
-struct security_informations : std::mutex {
+struct security_informations : std::shared_mutex {
   std::unique_ptr<byte[]> descriptor = nullptr;
   DWORD descriptor_size = 0;
 
@@ -121,12 +121,12 @@ class filenode {
  private:
   filenode() = default;
 
-  std::mutex _data_mutex;
+  std::shared_mutex _data_mutex;
   // _data_mutex need to be aquired
   std::vector<uint8_t> _data;
   std::unordered_map<std::wstring, std::shared_ptr<filenode> > _streams;
 
-  std::mutex _fileName_mutex;
+  std::shared_mutex _fileName_mutex;
   // _fileName_mutex need to be aquired
   std::wstring _fileName;
 };
diff --git a/samples/dokan_memfs/memfs_operations.cpp b/samples/dokan_memfs/memfs_operations.cpp
index db158a580..6bbcc1436 100644
--- a/samples/dokan_memfs/memfs_operations.cpp
+++ b/samples/dokan_memfs/memfs_operations.cpp
@@ -655,7 +655,7 @@ static NTSTATUS DOKAN_CALLBACK memfs_getfilesecurity(
 
   if (!f) return STATUS_OBJECT_NAME_NOT_FOUND;
 
-  std::lock_guard<std::mutex> lockFile(f->security);
+  std::shared_lock lockFile(f->security);
 
   // This will make dokan library return a default security descriptor
   if (!f->security.descriptor) return STATUS_NOT_IMPLEMENTED;
@@ -707,7 +707,7 @@ static NTSTATUS DOKAN_CALLBACK memfs_setfilesecurity(
 
   if (!f) return STATUS_OBJECT_NAME_NOT_FOUND;
 
-  std::lock_guard<std::mutex> securityLock(f->security);
+  std::unique_lock securityLock(f->security);
 
   // SetPrivateObjectSecurity - ObjectsSecurityDescriptor
   // The memory for the security descriptor must be allocated from the process