VFS implementation for local storage service (#396)

currently, only Windows (using Projected File System) is supported

3 files changed, 112 insertions, 0 deletions

diff --git a/src/zenvfs/include/zenvfs/projfs.h b/src/zenvfs/include/zenvfs/projfs.h
new file mode 100644
index 000000000..8a89c2835
--- /dev/null
+++ b/src/zenvfs/include/zenvfs/projfs.h
@@ -0,0 +1,14 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#pragma once
+
+#include "zenvfs.h"
+
+#if ZEN_WITH_VFS
+
+namespace zen {
+
+bool IsProjFsAvailable();
+
+}  // namespace zen
+#endif
diff --git a/src/zenvfs/include/zenvfs/vfs.h b/src/zenvfs/include/zenvfs/vfs.h
new file mode 100644
index 000000000..412970860
--- /dev/null
+++ b/src/zenvfs/include/zenvfs/vfs.h
@@ -0,0 +1,89 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#pragma once
+
+#include "zenvfs.h"
+
+#if ZEN_WITH_VFS
+
+#	include <zencore/zencore.h>
+#	include <zencore/refcount.h>
+#	include <zencore/uid.h>
+
+#	include <string_view>
+#	include <memory>
+#	include <vector>
+
+namespace zen {
+
+struct VfsProvider;
+
+//////////////////////////////////////////////////////////////////////////
+
+struct VfsTreeNode;
+
+struct VfsTreeDataSource : public RefCounted
+{
+	virtual void ReadNamedData(std::string_view Path, void* Buffer, uint64_t ByteOffset, uint64_t ByteCount) = 0;
+	virtual void ReadChunkData(const Oid& ChunkId, void* Buffer, uint64_t ByteOffset, uint64_t ByteCount)	 = 0;
+	virtual void PopulateDirectory(std::string NodePath, VfsTreeNode& DirNode)								 = 0;
+};
+
+struct VfsTreeNode
+{
+	inline VfsTreeNode(VfsTreeNode* InParent) : ParentNode(InParent) {}
+
+	const std::string_view GetName() const { return Name; }
+	uint64_t			   GetFileSize() const { return FileSize; }
+	VfsTreeDataSource*	   GetDataSource() const { return DataSource.Get(); }
+	const Oid&			   GetChunkId() const { return ChunkId; }
+
+	const std::string GetPath() const;
+
+	VfsTreeNode* FindNode(std::wstring_view NodeName);
+	VfsTreeNode* FindNode(std::string_view NodeName);
+
+	void AddVirtualNode(std::string_view NodeName, Ref<VfsTreeDataSource>&& DataSource);
+	void AddFileNode(std::string_view NodeName, uint64_t InFileSize, Oid InChunkId, Ref<VfsTreeDataSource> DataSource = {});
+	void NormalizeTree();
+	bool IsDirectory() const;
+	void PopulateVirtualNode();
+
+	const std::vector<std::unique_ptr<VfsTreeNode>>& GetChildren() const { return ChildArray; }
+	std::vector<std::unique_ptr<VfsTreeNode>>&		 GetChildren() { return ChildArray; }
+
+private:
+	std::string			   Name;
+	uint64_t			   FileSize = 0;
+	Oid					   ChunkId	= Oid::Zero;
+	Ref<VfsTreeDataSource> DataSource;
+
+	inline static const uint64_t			  DirectoryMarker = ~uint64_t(0);
+	std::vector<std::unique_ptr<VfsTreeNode>> ChildArray;
+	VfsTreeNode*							  ParentNode = nullptr;
+
+	VfsTreeNode* AddNewChildNode() { return ChildArray.emplace_back(std::make_unique<VfsTreeNode>(this)).get(); }
+
+	void GetPath(StringBuilderBase& Path) const;
+};
+
+//////////////////////////////////////////////////////////////////////////
+
+class VfsHost
+{
+public:
+	VfsHost(std::string_view VfsRootPath);
+	~VfsHost();
+
+	void Initialize();
+	void AddMount(std::string_view Mountpoint, Ref<VfsTreeDataSource>&& DataSource);
+	void Run();
+	void RequestStop();
+	void Cleanup();
+
+private:
+	VfsProvider* m_Provider = nullptr;
+};
+
+}  // namespace zen
+#endif
diff --git a/src/zenvfs/include/zenvfs/zenvfs.h b/src/zenvfs/include/zenvfs/zenvfs.h
new file mode 100644
index 000000000..c70368a1d
--- /dev/null
+++ b/src/zenvfs/include/zenvfs/zenvfs.h
@@ -0,0 +1,9 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#pragma once
+
+#include <zencore/zencore.h>
+
+#ifndef ZEN_WITH_VFS
+#	define ZEN_WITH_VFS ZEN_PLATFORM_WINDOWS
+#endif