5 files changed, 525 insertions, 87 deletions

diff --git a/src/core/file_sys/savedata_factory.h b/src/core/file_sys/savedata_factory.h
index e3a578c0f..f3cf50d5a 100644
--- a/src/core/file_sys/savedata_factory.h
+++ b/src/core/file_sys/savedata_factory.h
@@ -7,6 +7,7 @@
 #include <memory>
 #include <string>
 #include "common/common_types.h"
+#include "common/swap.h"
 #include "core/hle/result.h"
 
 namespace FileSys {
diff --git a/src/core/file_sys/vfs.cpp b/src/core/file_sys/vfs.cpp
index dae1c16ef..24e158962 100644
--- a/src/core/file_sys/vfs.cpp
+++ b/src/core/file_sys/vfs.cpp
@@ -4,12 +4,160 @@
 
 #include <algorithm>
 #include <numeric>
+#include <string>
+#include "common/common_paths.h"
 #include "common/file_util.h"
 #include "common/logging/backend.h"
 #include "core/file_sys/vfs.h"
 
 namespace FileSys {
 
+VfsFilesystem::VfsFilesystem(VirtualDir root_) : root(std::move(root_)) {}
+
+VfsFilesystem::~VfsFilesystem() = default;
+
+std::string VfsFilesystem::GetName() const {
+    return root->GetName();
+}
+
+bool VfsFilesystem::IsReadable() const {
+    return root->IsReadable();
+}
+
+bool VfsFilesystem::IsWritable() const {
+    return root->IsWritable();
+}
+
+VfsEntryType VfsFilesystem::GetEntryType(std::string_view path_) const {
+    const auto path = FileUtil::SanitizePath(path_);
+    if (root->GetFileRelative(path) != nullptr)
+        return VfsEntryType::File;
+    if (root->GetDirectoryRelative(path) != nullptr)
+        return VfsEntryType::Directory;
+
+    return VfsEntryType::None;
+}
+
+VirtualFile VfsFilesystem::OpenFile(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_);
+    return root->GetFileRelative(path);
+}
+
+VirtualFile VfsFilesystem::CreateFile(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_);
+    return root->CreateFileRelative(path);
+}
+
+VirtualFile VfsFilesystem::CopyFile(std::string_view old_path_, std::string_view new_path_) {
+    const auto old_path = FileUtil::SanitizePath(old_path_);
+    const auto new_path = FileUtil::SanitizePath(new_path_);
+
+    // VfsDirectory impls are only required to implement copy across the current directory.
+    if (FileUtil::GetParentPath(old_path) == FileUtil::GetParentPath(new_path)) {
+        if (!root->Copy(FileUtil::GetFilename(old_path), FileUtil::GetFilename(new_path)))
+            return nullptr;
+        return OpenFile(new_path, Mode::ReadWrite);
+    }
+
+    // Do it using RawCopy. Non-default impls are encouraged to optimize this.
+    const auto old_file = OpenFile(old_path, Mode::Read);
+    if (old_file == nullptr)
+        return nullptr;
+    auto new_file = OpenFile(new_path, Mode::Read);
+    if (new_file != nullptr)
+        return nullptr;
+    new_file = CreateFile(new_path, Mode::Write);
+    if (new_file == nullptr)
+        return nullptr;
+    if (!VfsRawCopy(old_file, new_file))
+        return nullptr;
+    return new_file;
+}
+
+VirtualFile VfsFilesystem::MoveFile(std::string_view old_path_, std::string_view new_path_) {
+    const auto old_path = FileUtil::SanitizePath(old_path_);
+    const auto new_path = FileUtil::SanitizePath(new_path_);
+
+    // Again, non-default impls are highly encouraged to provide a more optimized version of this.
+    auto out = CopyFile(old_path_, new_path_);
+    if (out == nullptr)
+        return nullptr;
+    if (DeleteFile(old_path))
+        return out;
+    return nullptr;
+}
+
+bool VfsFilesystem::DeleteFile(std::string_view path_) {
+    const auto path = FileUtil::SanitizePath(path_);
+    auto parent = OpenDirectory(FileUtil::GetParentPath(path), Mode::Write);
+    if (parent == nullptr)
+        return false;
+    return parent->DeleteFile(FileUtil::GetFilename(path));
+}
+
+VirtualDir VfsFilesystem::OpenDirectory(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_);
+    return root->GetDirectoryRelative(path);
+}
+
+VirtualDir VfsFilesystem::CreateDirectory(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_);
+    return root->CreateDirectoryRelative(path);
+}
+
+VirtualDir VfsFilesystem::CopyDirectory(std::string_view old_path_, std::string_view new_path_) {
+    const auto old_path = FileUtil::SanitizePath(old_path_);
+    const auto new_path = FileUtil::SanitizePath(new_path_);
+
+    // Non-default impls are highly encouraged to provide a more optimized version of this.
+    auto old_dir = OpenDirectory(old_path, Mode::Read);
+    if (old_dir == nullptr)
+        return nullptr;
+    auto new_dir = OpenDirectory(new_path, Mode::Read);
+    if (new_dir != nullptr)
+        return nullptr;
+    new_dir = CreateDirectory(new_path, Mode::Write);
+    if (new_dir == nullptr)
+        return nullptr;
+
+    for (const auto& file : old_dir->GetFiles()) {
+        const auto x =
+            CopyFile(old_path + DIR_SEP + file->GetName(), new_path + DIR_SEP + file->GetName());
+        if (x == nullptr)
+            return nullptr;
+    }
+
+    for (const auto& dir : old_dir->GetSubdirectories()) {
+        const auto x =
+            CopyDirectory(old_path + DIR_SEP + dir->GetName(), new_path + DIR_SEP + dir->GetName());
+        if (x == nullptr)
+            return nullptr;
+    }
+
+    return new_dir;
+}
+
+VirtualDir VfsFilesystem::MoveDirectory(std::string_view old_path_, std::string_view new_path_) {
+    const auto old_path = FileUtil::SanitizePath(old_path_);
+    const auto new_path = FileUtil::SanitizePath(new_path_);
+
+    // Non-default impls are highly encouraged to provide a more optimized version of this.
+    auto out = CopyDirectory(old_path_, new_path_);
+    if (out == nullptr)
+        return nullptr;
+    if (DeleteDirectory(old_path))
+        return out;
+    return nullptr;
+}
+
+bool VfsFilesystem::DeleteDirectory(std::string_view path_) {
+    const auto path = FileUtil::SanitizePath(path_);
+    auto parent = OpenDirectory(FileUtil::GetParentPath(path), Mode::Write);
+    if (parent == nullptr)
+        return false;
+    return parent->DeleteSubdirectoryRecursive(FileUtil::GetFilename(path));
+}
+
 VfsFile::~VfsFile() = default;
 
 std::string VfsFile::GetExtension() const {
diff --git a/src/core/file_sys/vfs.h b/src/core/file_sys/vfs.h
index fab9e2b45..141a053ce 100644
--- a/src/core/file_sys/vfs.h
+++ b/src/core/file_sys/vfs.h
@@ -11,14 +11,74 @@
 #include <vector>
 #include "boost/optional.hpp"
 #include "common/common_types.h"
+#include "core/file_sys/mode.h"
 
 namespace FileSys {
+
+struct VfsFilesystem;
 struct VfsFile;
 struct VfsDirectory;
 
-// Convenience typedefs to use VfsDirectory and VfsFile
-using VirtualDir = std::shared_ptr<FileSys::VfsDirectory>;
-using VirtualFile = std::shared_ptr<FileSys::VfsFile>;
+// Convenience typedefs to use Vfs* interfaces
+using VirtualFilesystem = std::shared_ptr<VfsFilesystem>;
+using VirtualDir = std::shared_ptr<VfsDirectory>;
+using VirtualFile = std::shared_ptr<VfsFile>;
+
+// An enumeration representing what can be at the end of a path in a VfsFilesystem
+enum class VfsEntryType {
+    None,
+    File,
+    Directory,
+};
+
+// A class representing an abstract filesystem. A default implementation given the root VirtualDir
+// is provided for convenience, but if the Vfs implementation has any additional state or
+// functionality, they will need to override.
+struct VfsFilesystem : NonCopyable {
+    VfsFilesystem(VirtualDir root);
+    virtual ~VfsFilesystem();
+
+    // Gets the friendly name for the filesystem.
+    virtual std::string GetName() const;
+
+    // Return whether or not the user has read permissions on this filesystem.
+    virtual bool IsReadable() const;
+    // Return whether or not the user has write permission on this filesystem.
+    virtual bool IsWritable() const;
+
+    // Determine if the entry at path is non-existant, a file, or a directory.
+    virtual VfsEntryType GetEntryType(std::string_view path) const;
+
+    // Opens the file with path relative to root. If it doesn't exist, returns nullptr.
+    virtual VirtualFile OpenFile(std::string_view path, Mode perms);
+    // Creates a new, empty file at path
+    virtual VirtualFile CreateFile(std::string_view path, Mode perms);
+    // Copies the file from old_path to new_path, returning the new file on success and nullptr on
+    // failure.
+    virtual VirtualFile CopyFile(std::string_view old_path, std::string_view new_path);
+    // Moves the file from old_path to new_path, returning the moved file on success and nullptr on
+    // failure.
+    virtual VirtualFile MoveFile(std::string_view old_path, std::string_view new_path);
+    // Deletes the file with path relative to root, returing true on success.
+    virtual bool DeleteFile(std::string_view path);
+
+    // Opens the directory with path relative to root. If it doesn't exist, returns nullptr.
+    virtual VirtualDir OpenDirectory(std::string_view path, Mode perms);
+    // Creates a new, empty directory at path
+    virtual VirtualDir CreateDirectory(std::string_view path, Mode perms);
+    // Copies the directory from old_path to new_path, returning the new directory on success and
+    // nullptr on failure.
+    virtual VirtualDir CopyDirectory(std::string_view old_path, std::string_view new_path);
+    // Moves the directory from old_path to new_path, returning the moved directory on success and
+    // nullptr on failure.
+    virtual VirtualDir MoveDirectory(std::string_view old_path, std::string_view new_path);
+    // Deletes the directory with path relative to root, returing true on success.
+    virtual bool DeleteDirectory(std::string_view path);
+
+protected:
+    // Root directory in default implementation.
+    VirtualDir root;
+};
 
 // A class representing a file in an abstract filesystem.
 struct VfsFile : NonCopyable {
diff --git a/src/core/file_sys/vfs_real.cpp b/src/core/file_sys/vfs_real.cpp
index 82d54da4a..1b5919737 100644
--- a/src/core/file_sys/vfs_real.cpp
+++ b/src/core/file_sys/vfs_real.cpp
@@ -6,7 +6,7 @@
 #include <cstddef>
 #include <iterator>
 #include <utility>
-
+#include "common/assert.h"
 #include "common/common_paths.h"
 #include "common/logging/log.h"
 #include "core/file_sys/vfs_real.h"
@@ -29,6 +29,8 @@ static std::string ModeFlagsToString(Mode mode) {
             mode_str = "a";
         else if (mode & Mode::Write)
             mode_str = "w";
+        else
+            UNREACHABLE_MSG("Invalid file open mode: {:02X}", static_cast<u8>(mode));
     }
 
     mode_str += "b";
@@ -36,8 +38,174 @@ static std::string ModeFlagsToString(Mode mode) {
     return mode_str;
 }
 
-RealVfsFile::RealVfsFile(const std::string& path_, Mode perms_)
-    : backing(path_, ModeFlagsToString(perms_).c_str()), path(path_),
+RealVfsFilesystem::RealVfsFilesystem() : VfsFilesystem(nullptr) {}
+
+std::string RealVfsFilesystem::GetName() const {
+    return "Real";
+}
+
+bool RealVfsFilesystem::IsReadable() const {
+    return true;
+}
+
+bool RealVfsFilesystem::IsWritable() const {
+    return true;
+}
+
+VfsEntryType RealVfsFilesystem::GetEntryType(std::string_view path_) const {
+    const auto path = FileUtil::SanitizePath(path_, FileUtil::DirectorySeparator::PlatformDefault);
+    if (!FileUtil::Exists(path))
+        return VfsEntryType::None;
+    if (FileUtil::IsDirectory(path))
+        return VfsEntryType::Directory;
+
+    return VfsEntryType::File;
+}
+
+VirtualFile RealVfsFilesystem::OpenFile(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_, FileUtil::DirectorySeparator::PlatformDefault);
+    if (cache.find(path) != cache.end()) {
+        auto weak = cache[path];
+        if (!weak.expired()) {
+            return std::shared_ptr<RealVfsFile>(new RealVfsFile(*this, weak.lock(), path, perms));
+        }
+    }
+
+    if (!FileUtil::Exists(path) && (perms & Mode::WriteAppend) != 0)
+        FileUtil::CreateEmptyFile(path);
+
+    auto backing = std::make_shared<FileUtil::IOFile>(path, ModeFlagsToString(perms).c_str());
+    cache[path] = backing;
+
+    // Cannot use make_shared as RealVfsFile constructor is private
+    return std::shared_ptr<RealVfsFile>(new RealVfsFile(*this, backing, path, perms));
+}
+
+VirtualFile RealVfsFilesystem::CreateFile(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_, FileUtil::DirectorySeparator::PlatformDefault);
+    if (!FileUtil::Exists(path) && !FileUtil::CreateEmptyFile(path))
+        return nullptr;
+    return OpenFile(path, perms);
+}
+
+VirtualFile RealVfsFilesystem::CopyFile(std::string_view old_path_, std::string_view new_path_) {
+    const auto old_path =
+        FileUtil::SanitizePath(old_path_, FileUtil::DirectorySeparator::PlatformDefault);
+    const auto new_path =
+        FileUtil::SanitizePath(new_path_, FileUtil::DirectorySeparator::PlatformDefault);
+
+    if (!FileUtil::Exists(old_path) || FileUtil::Exists(new_path) ||
+        FileUtil::IsDirectory(old_path) || !FileUtil::Copy(old_path, new_path))
+        return nullptr;
+    return OpenFile(new_path, Mode::ReadWrite);
+}
+
+VirtualFile RealVfsFilesystem::MoveFile(std::string_view old_path_, std::string_view new_path_) {
+    const auto old_path =
+        FileUtil::SanitizePath(old_path_, FileUtil::DirectorySeparator::PlatformDefault);
+    const auto new_path =
+        FileUtil::SanitizePath(new_path_, FileUtil::DirectorySeparator::PlatformDefault);
+
+    if (!FileUtil::Exists(old_path) || FileUtil::Exists(new_path) ||
+        FileUtil::IsDirectory(old_path) || !FileUtil::Rename(old_path, new_path))
+        return nullptr;
+
+    if (cache.find(old_path) != cache.end()) {
+        auto cached = cache[old_path];
+        if (!cached.expired()) {
+            auto file = cached.lock();
+            file->Open(new_path, "r+b");
+            cache.erase(old_path);
+            cache[new_path] = file;
+        }
+    }
+    return OpenFile(new_path, Mode::ReadWrite);
+}
+
+bool RealVfsFilesystem::DeleteFile(std::string_view path_) {
+    const auto path = FileUtil::SanitizePath(path_, FileUtil::DirectorySeparator::PlatformDefault);
+    if (cache.find(path) != cache.end()) {
+        if (!cache[path].expired())
+            cache[path].lock()->Close();
+        cache.erase(path);
+    }
+    return FileUtil::Delete(path);
+}
+
+VirtualDir RealVfsFilesystem::OpenDirectory(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_, FileUtil::DirectorySeparator::PlatformDefault);
+    // Cannot use make_shared as RealVfsDirectory constructor is private
+    return std::shared_ptr<RealVfsDirectory>(new RealVfsDirectory(*this, path, perms));
+}
+
+VirtualDir RealVfsFilesystem::CreateDirectory(std::string_view path_, Mode perms) {
+    const auto path = FileUtil::SanitizePath(path_, FileUtil::DirectorySeparator::PlatformDefault);
+    if (!FileUtil::Exists(path) && !FileUtil::CreateDir(path))
+        return nullptr;
+    // Cannot use make_shared as RealVfsDirectory constructor is private
+    return std::shared_ptr<RealVfsDirectory>(new RealVfsDirectory(*this, path, perms));
+}
+
+VirtualDir RealVfsFilesystem::CopyDirectory(std::string_view old_path_,
+                                            std::string_view new_path_) {
+    const auto old_path =
+        FileUtil::SanitizePath(old_path_, FileUtil::DirectorySeparator::PlatformDefault);
+    const auto new_path =
+        FileUtil::SanitizePath(new_path_, FileUtil::DirectorySeparator::PlatformDefault);
+    if (!FileUtil::Exists(old_path) || FileUtil::Exists(new_path) ||
+        !FileUtil::IsDirectory(old_path))
+        return nullptr;
+    FileUtil::CopyDir(old_path, new_path);
+    return OpenDirectory(new_path, Mode::ReadWrite);
+}
+
+VirtualDir RealVfsFilesystem::MoveDirectory(std::string_view old_path_,
+                                            std::string_view new_path_) {
+    const auto old_path =
+        FileUtil::SanitizePath(old_path_, FileUtil::DirectorySeparator::PlatformDefault);
+    const auto new_path =
+        FileUtil::SanitizePath(new_path_, FileUtil::DirectorySeparator::PlatformDefault);
+    if (!FileUtil::Exists(old_path) || FileUtil::Exists(new_path) ||
+        FileUtil::IsDirectory(old_path) || !FileUtil::Rename(old_path, new_path))
+        return nullptr;
+
+    for (auto& kv : cache) {
+        // Path in cache starts with old_path
+        if (kv.first.rfind(old_path, 0) == 0) {
+            const auto file_old_path =
+                FileUtil::SanitizePath(kv.first, FileUtil::DirectorySeparator::PlatformDefault);
+            const auto file_new_path =
+                FileUtil::SanitizePath(new_path + DIR_SEP + kv.first.substr(old_path.size()),
+                                       FileUtil::DirectorySeparator::PlatformDefault);
+            auto cached = cache[file_old_path];
+            if (!cached.expired()) {
+                auto file = cached.lock();
+                file->Open(file_new_path, "r+b");
+                cache.erase(file_old_path);
+                cache[file_new_path] = file;
+            }
+        }
+    }
+
+    return OpenDirectory(new_path, Mode::ReadWrite);
+}
+
+bool RealVfsFilesystem::DeleteDirectory(std::string_view path_) {
+    const auto path = FileUtil::SanitizePath(path_, FileUtil::DirectorySeparator::PlatformDefault);
+    for (auto& kv : cache) {
+        // Path in cache starts with old_path
+        if (kv.first.rfind(path, 0) == 0) {
+            if (!cache[kv.first].expired())
+                cache[kv.first].lock()->Close();
+            cache.erase(kv.first);
+        }
+    }
+    return FileUtil::DeleteDirRecursively(path);
+}
+
+RealVfsFile::RealVfsFile(RealVfsFilesystem& base_, std::shared_ptr<FileUtil::IOFile> backing_,
+                         const std::string& path_, Mode perms_)
+    : base(base_), backing(std::move(backing_)), path(path_),
       parent_path(FileUtil::GetParentPath(path_)),
       path_components(FileUtil::SplitPathComponents(path_)),
       parent_components(FileUtil::SliceVector(path_components, 0, path_components.size() - 1)),
@@ -48,15 +216,15 @@ std::string RealVfsFile::GetName() const {
 }
 
 size_t RealVfsFile::GetSize() const {
-    return backing.GetSize();
+    return backing->GetSize();
 }
 
 bool RealVfsFile::Resize(size_t new_size) {
-    return backing.Resize(new_size);
+    return backing->Resize(new_size);
 }
 
 std::shared_ptr<VfsDirectory> RealVfsFile::GetContainingDirectory() const {
-    return std::make_shared<RealVfsDirectory>(parent_path, perms);
+    return base.OpenDirectory(parent_path, perms);
 }
 
 bool RealVfsFile::IsWritable() const {
@@ -68,62 +236,118 @@ bool RealVfsFile::IsReadable() const {
 }
 
 size_t RealVfsFile::Read(u8* data, size_t length, size_t offset) const {
-    if (!backing.Seek(offset, SEEK_SET))
+    if (!backing->Seek(offset, SEEK_SET))
         return 0;
-    return backing.ReadBytes(data, length);
+    return backing->ReadBytes(data, length);
 }
 
 size_t RealVfsFile::Write(const u8* data, size_t length, size_t offset) {
-    if (!backing.Seek(offset, SEEK_SET))
+    if (!backing->Seek(offset, SEEK_SET))
         return 0;
-    return backing.WriteBytes(data, length);
+    return backing->WriteBytes(data, length);
 }
 
 bool RealVfsFile::Rename(std::string_view name) {
-    std::string name_str(name.begin(), name.end());
-    const auto out = FileUtil::Rename(GetName(), name_str);
+    return base.MoveFile(path, parent_path + DIR_SEP + std::string(name)) != nullptr;
+}
+
+bool RealVfsFile::Close() {
+    return backing->Close();
+}
 
-    path = (parent_path + DIR_SEP).append(name);
-    path_components = parent_components;
-    path_components.push_back(std::move(name_str));
-    backing = FileUtil::IOFile(path, ModeFlagsToString(perms).c_str());
+// TODO(DarkLordZach): MSVC would not let me combine the following two functions using 'if
+// constexpr' because there is a compile error in the branch not used.
+
+template <>
+std::vector<VirtualFile> RealVfsDirectory::IterateEntries<RealVfsFile, VfsFile>() const {
+    if (perms == Mode::Append)
+        return {};
+
+    std::vector<VirtualFile> out;
+    FileUtil::ForeachDirectoryEntry(
+        nullptr, path,
+        [&out, this](u64* entries_out, const std::string& directory, const std::string& filename) {
+            const std::string full_path = directory + DIR_SEP + filename;
+            if (!FileUtil::IsDirectory(full_path))
+                out.emplace_back(base.OpenFile(full_path, perms));
+            return true;
+        });
 
     return out;
 }
 
-bool RealVfsFile::Close() {
-    return backing.Close();
+template <>
+std::vector<VirtualDir> RealVfsDirectory::IterateEntries<RealVfsDirectory, VfsDirectory>() const {
+    if (perms == Mode::Append)
+        return {};
+
+    std::vector<VirtualDir> out;
+    FileUtil::ForeachDirectoryEntry(
+        nullptr, path,
+        [&out, this](u64* entries_out, const std::string& directory, const std::string& filename) {
+            const std::string full_path = directory + DIR_SEP + filename;
+            if (FileUtil::IsDirectory(full_path))
+                out.emplace_back(base.OpenDirectory(full_path, perms));
+            return true;
+        });
+
+    return out;
 }
 
-RealVfsDirectory::RealVfsDirectory(const std::string& path_, Mode perms_)
-    : path(FileUtil::RemoveTrailingSlash(path_)), parent_path(FileUtil::GetParentPath(path)),
+RealVfsDirectory::RealVfsDirectory(RealVfsFilesystem& base_, const std::string& path_, Mode perms_)
+    : base(base_), path(FileUtil::RemoveTrailingSlash(path_)),
+      parent_path(FileUtil::GetParentPath(path)),
       path_components(FileUtil::SplitPathComponents(path)),
       parent_components(FileUtil::SliceVector(path_components, 0, path_components.size() - 1)),
       perms(perms_) {
     if (!FileUtil::Exists(path) && perms & Mode::WriteAppend)
         FileUtil::CreateDir(path);
+}
 
-    if (perms == Mode::Append)
-        return;
+std::shared_ptr<VfsFile> RealVfsDirectory::GetFileRelative(std::string_view path) const {
+    const auto full_path = FileUtil::SanitizePath(this->path + DIR_SEP + std::string(path));
+    if (!FileUtil::Exists(full_path))
+        return nullptr;
+    return base.OpenFile(full_path, perms);
+}
 
-    FileUtil::ForeachDirectoryEntry(
-        nullptr, path,
-        [this](u64* entries_out, const std::string& directory, const std::string& filename) {
-            std::string full_path = directory + DIR_SEP + filename;
-            if (FileUtil::IsDirectory(full_path))
-                subdirectories.emplace_back(std::make_shared<RealVfsDirectory>(full_path, perms));
-            else
-                files.emplace_back(std::make_shared<RealVfsFile>(full_path, perms));
-            return true;
-        });
+std::shared_ptr<VfsDirectory> RealVfsDirectory::GetDirectoryRelative(std::string_view path) const {
+    const auto full_path = FileUtil::SanitizePath(this->path + DIR_SEP + std::string(path));
+    if (!FileUtil::Exists(full_path))
+        return nullptr;
+    return base.OpenDirectory(full_path, perms);
+}
+
+std::shared_ptr<VfsFile> RealVfsDirectory::GetFile(std::string_view name) const {
+    return GetFileRelative(name);
+}
+
+std::shared_ptr<VfsDirectory> RealVfsDirectory::GetSubdirectory(std::string_view name) const {
+    return GetDirectoryRelative(name);
+}
+
+std::shared_ptr<VfsFile> RealVfsDirectory::CreateFileRelative(std::string_view path) {
+    const auto full_path = FileUtil::SanitizePath(this->path + DIR_SEP + std::string(path));
+    return base.CreateFile(full_path, perms);
+}
+
+std::shared_ptr<VfsDirectory> RealVfsDirectory::CreateDirectoryRelative(std::string_view path) {
+    const auto full_path = FileUtil::SanitizePath(this->path + DIR_SEP + std::string(path));
+    auto parent = std::string(FileUtil::GetParentPath(full_path));
+    return base.CreateDirectory(full_path, perms);
+}
+
+bool RealVfsDirectory::DeleteSubdirectoryRecursive(std::string_view name) {
+    auto full_path = FileUtil::SanitizePath(this->path + DIR_SEP + std::string(name));
+    return base.DeleteDirectory(full_path);
 }
 
 std::vector<std::shared_ptr<VfsFile>> RealVfsDirectory::GetFiles() const {
-    return files;
+    return IterateEntries<RealVfsFile, VfsFile>();
 }
 
 std::vector<std::shared_ptr<VfsDirectory>> RealVfsDirectory::GetSubdirectories() const {
-    return subdirectories;
+    return IterateEntries<RealVfsDirectory, VfsDirectory>();
 }
 
 bool RealVfsDirectory::IsWritable() const {
@@ -142,57 +366,32 @@ std::shared_ptr<VfsDirectory> RealVfsDirectory::GetParentDirectory() const {
     if (path_components.size() <= 1)
         return nullptr;
 
-    return std::make_shared<RealVfsDirectory>(parent_path, perms);
+    return base.OpenDirectory(parent_path, perms);
 }
 
 std::shared_ptr<VfsDirectory> RealVfsDirectory::CreateSubdirectory(std::string_view name) {
     const std::string subdir_path = (path + DIR_SEP).append(name);
-
-    if (!FileUtil::CreateDir(subdir_path)) {
-        return nullptr;
-    }
-
-    subdirectories.emplace_back(std::make_shared<RealVfsDirectory>(subdir_path, perms));
-    return subdirectories.back();
+    return base.CreateDirectory(subdir_path, perms);
 }
 
 std::shared_ptr<VfsFile> RealVfsDirectory::CreateFile(std::string_view name) {
     const std::string file_path = (path + DIR_SEP).append(name);
-
-    if (!FileUtil::CreateEmptyFile(file_path)) {
-        return nullptr;
-    }
-
-    files.emplace_back(std::make_shared<RealVfsFile>(file_path, perms));
-    return files.back();
+    return base.CreateFile(file_path, perms);
 }
 
 bool RealVfsDirectory::DeleteSubdirectory(std::string_view name) {
     const std::string subdir_path = (path + DIR_SEP).append(name);
-
-    return FileUtil::DeleteDirRecursively(subdir_path);
+    return base.DeleteDirectory(subdir_path);
 }
 
 bool RealVfsDirectory::DeleteFile(std::string_view name) {
-    const auto file = GetFile(name);
-
-    if (file == nullptr) {
-        return false;
-    }
-
-    files.erase(std::find(files.begin(), files.end(), file));
-
-    auto real_file = std::static_pointer_cast<RealVfsFile>(file);
-    real_file->Close();
-
     const std::string file_path = (path + DIR_SEP).append(name);
-    return FileUtil::Delete(file_path);
+    return base.DeleteFile(file_path);
 }
 
 bool RealVfsDirectory::Rename(std::string_view name) {
     const std::string new_name = (parent_path + DIR_SEP).append(name);
-
-    return FileUtil::Rename(path, new_name);
+    return base.MoveFile(path, new_name) != nullptr;
 }
 
 std::string RealVfsDirectory::GetFullPath() const {
@@ -202,16 +401,6 @@ std::string RealVfsDirectory::GetFullPath() const {
 }
 
 bool RealVfsDirectory::ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) {
-    const auto iter = std::find(files.begin(), files.end(), file);
-    if (iter == files.end())
-        return false;
-
-    const std::ptrdiff_t offset = std::distance(files.begin(), iter);
-    files[offset] = files.back();
-    files.pop_back();
-
-    subdirectories.emplace_back(std::move(dir));
-
-    return true;
+    return false;
 }
 } // namespace FileSys
diff --git a/src/core/file_sys/vfs_real.h b/src/core/file_sys/vfs_real.h
index 243d58576..8a1e79ef6 100644
--- a/src/core/file_sys/vfs_real.h
+++ b/src/core/file_sys/vfs_real.h
@@ -6,18 +6,45 @@
 
 #include <string_view>
 
+#include <boost/container/flat_map.hpp>
 #include "common/file_util.h"
 #include "core/file_sys/mode.h"
 #include "core/file_sys/vfs.h"
 
 namespace FileSys {
 
+class RealVfsFilesystem : public VfsFilesystem {
+public:
+    RealVfsFilesystem();
+
+    std::string GetName() const override;
+    bool IsReadable() const override;
+    bool IsWritable() const override;
+    VfsEntryType GetEntryType(std::string_view path) const override;
+    VirtualFile OpenFile(std::string_view path, Mode perms = Mode::Read) override;
+    VirtualFile CreateFile(std::string_view path, Mode perms = Mode::ReadWrite) override;
+    VirtualFile CopyFile(std::string_view old_path, std::string_view new_path) override;
+    VirtualFile MoveFile(std::string_view old_path, std::string_view new_path) override;
+    bool DeleteFile(std::string_view path) override;
+    VirtualDir OpenDirectory(std::string_view path, Mode perms = Mode::Read) override;
+    VirtualDir CreateDirectory(std::string_view path, Mode perms = Mode::ReadWrite) override;
+    VirtualDir CopyDirectory(std::string_view old_path, std::string_view new_path) override;
+    VirtualDir MoveDirectory(std::string_view old_path, std::string_view new_path) override;
+    bool DeleteDirectory(std::string_view path) override;
+
+private:
+    boost::container::flat_map<std::string, std::weak_ptr<FileUtil::IOFile>> cache;
+};
+
 // An implmentation of VfsFile that represents a file on the user's computer.
-struct RealVfsFile : public VfsFile {
-    friend struct RealVfsDirectory;
+class RealVfsFile : public VfsFile {
+    friend class RealVfsDirectory;
+    friend class RealVfsFilesystem;
 
-    RealVfsFile(const std::string& name, Mode perms = Mode::Read);
+    RealVfsFile(RealVfsFilesystem& base, std::shared_ptr<FileUtil::IOFile> backing,
+                const std::string& path, Mode perms = Mode::Read);
 
+public:
     std::string GetName() const override;
     size_t GetSize() const override;
     bool Resize(size_t new_size) override;
@@ -31,7 +58,8 @@ struct RealVfsFile : public VfsFile {
 private:
     bool Close();
 
-    FileUtil::IOFile backing;
+    RealVfsFilesystem& base;
+    std::shared_ptr<FileUtil::IOFile> backing;
     std::string path;
     std::string parent_path;
     std::vector<std::string> path_components;
@@ -40,9 +68,19 @@ private:
 };
 
 // An implementation of VfsDirectory that represents a directory on the user's computer.
-struct RealVfsDirectory : public VfsDirectory {
-    RealVfsDirectory(const std::string& path, Mode perms = Mode::Read);
+class RealVfsDirectory : public VfsDirectory {
+    friend class RealVfsFilesystem;
 
+    RealVfsDirectory(RealVfsFilesystem& base, const std::string& path, Mode perms = Mode::Read);
+
+public:
+    std::shared_ptr<VfsFile> GetFileRelative(std::string_view path) const override;
+    std::shared_ptr<VfsDirectory> GetDirectoryRelative(std::string_view path) const override;
+    std::shared_ptr<VfsFile> GetFile(std::string_view name) const override;
+    std::shared_ptr<VfsDirectory> GetSubdirectory(std::string_view name) const override;
+    std::shared_ptr<VfsFile> CreateFileRelative(std::string_view path) override;
+    std::shared_ptr<VfsDirectory> CreateDirectoryRelative(std::string_view path) override;
+    bool DeleteSubdirectoryRecursive(std::string_view name) override;
     std::vector<std::shared_ptr<VfsFile>> GetFiles() const override;
     std::vector<std::shared_ptr<VfsDirectory>> GetSubdirectories() const override;
     bool IsWritable() const override;
@@ -60,13 +98,15 @@ protected:
     bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
 
 private:
+    template <typename T, typename R>
+    std::vector<std::shared_ptr<R>> IterateEntries() const;
+
+    RealVfsFilesystem& base;
     std::string path;
     std::string parent_path;
     std::vector<std::string> path_components;
     std::vector<std::string> parent_components;
     Mode perms;
-    std::vector<std::shared_ptr<VfsFile>> files;
-    std::vector<std::shared_ptr<VfsDirectory>> subdirectories;
 };
 
 } // namespace FileSys