Virtual Filesystem (#597)

* Add VfsFile and VfsDirectory classes

* Finish abstract Vfs classes

* Implement RealVfsFile (computer fs backend)

* Finish RealVfsFile and RealVfsDirectory

* Finished OffsetVfsFile

* More changes

* Fix import paths

* Major refactor

* Remove double const

* Use experimental/filesystem or filesystem depending on compiler

* Port partition_filesystem

* More changes

* More Overhaul

* FSP_SRV fixes

* Fixes and testing

* Try to get filesystem to compile

* Filesystem on linux

* Remove std::filesystem and document/test

* Compile fixes

* Missing include

* Bug fixes

* Fixes

* Rename v_file and v_dir

* clang-format fix

* Rename NGLOG_* to LOG_*

* Most review changes

* Fix TODO

* Guess 'main' to be Directory by filename

src/common/file_util.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <sstream>
 #include "common/assert.h"
 #include "common/common_funcs.h"
 #include "common/common_paths.h"
@@ -386,7 +387,7 @@ u64 GetSize(FILE* f) {
 bool CreateEmptyFile(const std::string& filename) {
     LOG_TRACE(Common_Filesystem, "{}", filename);
 
-    if (!FileUtil::IOFile(filename, "wb")) {
+    if (!FileUtil::IOFile(filename, "wb").IsOpen()) {
         LOG_ERROR(Common_Filesystem, "failed {}: {}", filename, GetLastErrorMsg());
         return false;
     }
@@ -750,7 +751,7 @@ size_t WriteStringToFile(bool text_file, const std::string& str, const char* fil
 size_t ReadFileToString(bool text_file, const char* filename, std::string& str) {
     IOFile file(filename, text_file ? "r" : "rb");
 
-    if (!file)
+    if (!file.IsOpen())
         return false;
 
     str.resize(static_cast<u32>(file.GetSize()));
@@ -799,6 +800,57 @@ void SplitFilename83(const std::string& filename, std::array<char, 9>& short_nam
     }
 }
 
+std::vector<std::string> SplitPathComponents(const std::string& filename) {
+    auto copy(filename);
+    std::replace(copy.begin(), copy.end(), '\\', '/');
+    std::vector<std::string> out;
+
+    std::stringstream stream(filename);
+    std::string item;
+    while (std::getline(stream, item, '/'))
+        out.push_back(std::move(item));
+
+    return out;
+}
+
+std::string GetParentPath(const std::string& path) {
+    auto out = path;
+    const auto name_bck_index = out.find_last_of('\\');
+    const auto name_fwd_index = out.find_last_of('/');
+    size_t name_index;
+    if (name_bck_index == std::string::npos || name_fwd_index == std::string::npos)
+        name_index = std::min<size_t>(name_bck_index, name_fwd_index);
+    else
+        name_index = std::max<size_t>(name_bck_index, name_fwd_index);
+
+    return out.erase(name_index);
+}
+
+std::string GetFilename(std::string path) {
+    std::replace(path.begin(), path.end(), '\\', '/');
+    auto name_index = path.find_last_of('/');
+    if (name_index == std::string::npos)
+        return "";
+    return path.substr(name_index + 1);
+}
+
+std::string GetExtensionFromFilename(const std::string& name) {
+    size_t index = name.find_last_of('.');
+    if (index == std::string::npos)
+        return "";
+
+    return name.substr(index + 1);
+}
+
+std::string RemoveTrailingSlash(const std::string& path) {
+    if (path.empty())
+        return path;
+    if (path.back() == '\\' || path.back() == '/')
+        return path.substr(0, path.size() - 1);
+
+    return path;
+}
+
 IOFile::IOFile() {}
 
 IOFile::IOFile(const std::string& filename, const char openmode[], int flags) {
@@ -820,7 +872,6 @@ IOFile& IOFile::operator=(IOFile&& other) noexcept {
 
 void IOFile::Swap(IOFile& other) noexcept {
     std::swap(m_file, other.m_file);
-    std::swap(m_good, other.m_good);
 }
 
 bool IOFile::Open(const std::string& filename, const char openmode[], int flags) {
@@ -837,16 +888,15 @@ bool IOFile::Open(const std::string& filename, const char openmode[], int flags)
     m_file = fopen(filename.c_str(), openmode);
 #endif
 
-    m_good = IsOpen();
-    return m_good;
+    return IsOpen();
 }
 
 bool IOFile::Close() {
     if (!IsOpen() || 0 != std::fclose(m_file))
-        m_good = false;
+        return false;
 
     m_file = nullptr;
-    return m_good;
+    return true;
 }
 
 u64 IOFile::GetSize() const {
@@ -856,11 +906,8 @@ u64 IOFile::GetSize() const {
     return 0;
 }
 
-bool IOFile::Seek(s64 off, int origin) {
-    if (!IsOpen() || 0 != fseeko(m_file, off, origin))
-        m_good = false;
-
-    return m_good;
+bool IOFile::Seek(s64 off, int origin) const {
+    return IsOpen() && 0 == fseeko(m_file, off, origin);
 }
 
 u64 IOFile::Tell() const {
@@ -871,26 +918,20 @@ u64 IOFile::Tell() const {
 }
 
 bool IOFile::Flush() {
-    if (!IsOpen() || 0 != std::fflush(m_file))
-        m_good = false;
-
-    return m_good;
+    return IsOpen() && 0 == std::fflush(m_file);
 }
 
 bool IOFile::Resize(u64 size) {
-    if (!IsOpen() || 0 !=
+    return IsOpen() && 0 ==
 #ifdef _WIN32
-                         // ector: _chsize sucks, not 64-bit safe
-                         // F|RES: changed to _chsize_s. i think it is 64-bit safe
-                         _chsize_s(_fileno(m_file), size)
+                           // ector: _chsize sucks, not 64-bit safe
+                           // F|RES: changed to _chsize_s. i think it is 64-bit safe
+                           _chsize_s(_fileno(m_file), size)
 #else
-                         // TODO: handle 64bit and growing
-                         ftruncate(fileno(m_file), size)
+                           // TODO: handle 64bit and growing
+                           ftruncate(fileno(m_file), size)
 #endif
-    )
-        m_good = false;
-
-    return m_good;
+        ;
 }
 
 } // namespace FileUtil

src/common/file_util.h

@@ -150,6 +150,31 @@ size_t ReadFileToString(bool text_file, const char* filename, std::string& str);
 void SplitFilename83(const std::string& filename, std::array<char, 9>& short_name,
                      std::array<char, 4>& extension);
 
+// Splits the path on '/' or '\' and put the components into a vector
+// i.e. "C:\Users\Yuzu\Documents\save.bin" becomes {"C:", "Users", "Yuzu", "Documents", "save.bin" }
+std::vector<std::string> SplitPathComponents(const std::string& filename);
+
+// Gets all of the text prior to the last '/' or '\' in the path.
+std::string GetParentPath(const std::string& path);
+
+// Gets the filename of the path
+std::string GetFilename(std::string path);
+
+// Gets the extension of the filename
+std::string GetExtensionFromFilename(const std::string& name);
+
+// Removes the final '/' or '\' if one exists
+std::string RemoveTrailingSlash(const std::string& path);
+
+// Creates a new vector containing indices [first, last) from the original.
+template <typename T>
+std::vector<T> SliceVector(const std::vector<T>& vector, size_t first, size_t last) {
+    if (first >= last)
+        return {};
+    last = std::min<size_t>(last, vector.size());
+    return std::vector<T>(vector.begin() + first, vector.begin() + first + last);
+}
+
 // simple wrapper for cstdlib file functions to
 // hopefully will make error checking easier
 // and make forgetting an fclose() harder
@@ -172,41 +197,27 @@ public:
     bool Close();
 
     template <typename T>
-    size_t ReadArray(T* data, size_t length) {
+    size_t ReadArray(T* data, size_t length) const {
         static_assert(std::is_trivially_copyable<T>(),
                       "Given array does not consist of trivially copyable objects");
 
-        if (!IsOpen()) {
-            m_good = false;
+        if (!IsOpen())
             return -1;
-        }
 
-        size_t items_read = std::fread(data, sizeof(T), length, m_file);
-        if (items_read != length)
-            m_good = false;
-
-        return items_read;
+        return std::fread(data, sizeof(T), length, m_file);
     }
 
     template <typename T>
     size_t WriteArray(const T* data, size_t length) {
         static_assert(std::is_trivially_copyable<T>(),
                       "Given array does not consist of trivially copyable objects");
-
-        if (!IsOpen()) {
-            m_good = false;
+        if (!IsOpen())
             return -1;
-        }
-
-        size_t items_written = std::fwrite(data, sizeof(T), length, m_file);
-        if (items_written != length)
-            m_good = false;
-
-        return items_written;
+        return std::fwrite(data, sizeof(T), length, m_file);
     }
 
     template <typename T>
-    size_t ReadBytes(T* data, size_t length) {
+    size_t ReadBytes(T* data, size_t length) const {
         static_assert(std::is_trivially_copyable<T>(), "T must be trivially copyable");
         return ReadArray(reinterpret_cast<char*>(data), length);
     }
@@ -231,15 +242,7 @@ public:
         return nullptr != m_file;
     }
 
-    // m_good is set to false when a read, write or other function fails
-    bool IsGood() const {
-        return m_good;
-    }
-    explicit operator bool() const {
-        return IsGood();
-    }
-
-    bool Seek(s64 off, int origin);
+    bool Seek(s64 off, int origin) const;
     u64 Tell() const;
     u64 GetSize() const;
     bool Resize(u64 size);
@@ -247,13 +250,11 @@ public:
 
     // clear error state
     void Clear() {
-        m_good = true;
         std::clearerr(m_file);
     }
 
 private:
     std::FILE* m_file = nullptr;
-    bool m_good = true;
 };
 
 } // namespace FileUtil

src/core/CMakeLists.txt

@@ -8,9 +8,9 @@ add_library(core STATIC
     core_cpu.h
     core_timing.cpp
     core_timing.h
+    file_sys/content_archive.cpp
+    file_sys/content_archive.h
     file_sys/directory.h
-    file_sys/disk_filesystem.cpp
-    file_sys/disk_filesystem.h
     file_sys/errors.h
     file_sys/filesystem.cpp
     file_sys/filesystem.h
@@ -20,15 +20,13 @@ add_library(core STATIC
     file_sys/path_parser.h
     file_sys/program_metadata.cpp
     file_sys/program_metadata.h
-    file_sys/romfs_factory.cpp
-    file_sys/romfs_factory.h
-    file_sys/romfs_filesystem.cpp
-    file_sys/romfs_filesystem.h
-    file_sys/savedata_factory.cpp
-    file_sys/savedata_factory.h
-    file_sys/sdmc_factory.cpp
-    file_sys/sdmc_factory.h
     file_sys/storage.h
+    file_sys/vfs.cpp
+    file_sys/vfs.h
+    file_sys/vfs_offset.cpp
+    file_sys/vfs_offset.h
+    file_sys/vfs_real.cpp
+    file_sys/vfs_real.h
     frontend/emu_window.cpp
     frontend/emu_window.h
     frontend/framebuffer_layout.cpp

src/core/core.cpp

@@ -19,6 +19,7 @@
 #include "core/loader/loader.h"
 #include "core/memory_setup.h"
 #include "core/settings.h"
+#include "file_sys/vfs_real.h"
 #include "video_core/video_core.h"
 
 namespace Core {
@@ -84,7 +85,7 @@ System::ResultStatus System::SingleStep() {
 }
 
 System::ResultStatus System::Load(EmuWindow* emu_window, const std::string& filepath) {
-    app_loader = Loader::GetLoader(filepath);
+    app_loader = Loader::GetLoader(std::make_shared<FileSys::RealVfsFile>(filepath));
 
     if (!app_loader) {
         LOG_CRITICAL(Core, "Failed to obtain loader for {}!", filepath);

src/core/file_sys/content_archive.cpp

@@ -0,0 +1,164 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/logging/log.h"
+#include "core/file_sys/content_archive.h"
+#include "core/file_sys/vfs_offset.h"
+#include "core/loader/loader.h"
+
+namespace FileSys {
+
+// Media offsets in headers are stored divided by 512. Mult. by this to get real offset.
+constexpr u64 MEDIA_OFFSET_MULTIPLIER = 0x200;
+
+constexpr u64 SECTION_HEADER_SIZE = 0x200;
+constexpr u64 SECTION_HEADER_OFFSET = 0x400;
+
+constexpr u32 IVFC_MAX_LEVEL = 6;
+
+enum class NCASectionFilesystemType : u8 { PFS0 = 0x2, ROMFS = 0x3 };
+
+struct NCASectionHeaderBlock {
+    INSERT_PADDING_BYTES(3);
+    NCASectionFilesystemType filesystem_type;
+    u8 crypto_type;
+    INSERT_PADDING_BYTES(3);
+};
+static_assert(sizeof(NCASectionHeaderBlock) == 0x8, "NCASectionHeaderBlock has incorrect size.");
+
+struct PFS0Superblock {
+    NCASectionHeaderBlock header_block;
+    std::array<u8, 0x20> hash;
+    u32_le size;
+    INSERT_PADDING_BYTES(4);
+    u64_le hash_table_offset;
+    u64_le hash_table_size;
+    u64_le pfs0_header_offset;
+    u64_le pfs0_size;
+    INSERT_PADDING_BYTES(432);
+};
+static_assert(sizeof(PFS0Superblock) == 0x200, "PFS0Superblock has incorrect size.");
+
+struct IVFCLevel {
+    u64_le offset;
+    u64_le size;
+    u32_le block_size;
+    u32_le reserved;
+};
+static_assert(sizeof(IVFCLevel) == 0x18, "IVFCLevel has incorrect size.");
+
+struct RomFSSuperblock {
+    NCASectionHeaderBlock header_block;
+    u32_le magic;
+    u32_le magic_number;
+    INSERT_PADDING_BYTES(8);
+    std::array<IVFCLevel, 6> levels;
+    INSERT_PADDING_BYTES(64);
+};
+static_assert(sizeof(RomFSSuperblock) == 0xE8, "RomFSSuperblock has incorrect size.");
+
+NCA::NCA(VirtualFile file_) : file(file_) {
+    if (sizeof(NCAHeader) != file->ReadObject(&header))
+        LOG_CRITICAL(Loader, "File reader errored out during header read.");
+
+    if (!IsValidNCA(header)) {
+        status = Loader::ResultStatus::ErrorInvalidFormat;
+        return;
+    }
+
+    std::ptrdiff_t number_sections =
+        std::count_if(std::begin(header.section_tables), std::end(header.section_tables),
+                      [](NCASectionTableEntry entry) { return entry.media_offset > 0; });
+
+    for (std::ptrdiff_t i = 0; i < number_sections; ++i) {
+        // Seek to beginning of this section.
+        NCASectionHeaderBlock block{};
+        if (sizeof(NCASectionHeaderBlock) !=
+            file->ReadObject(&block, SECTION_HEADER_OFFSET + i * SECTION_HEADER_SIZE))
+            LOG_CRITICAL(Loader, "File reader errored out during header read.");
+
+        if (block.filesystem_type == NCASectionFilesystemType::ROMFS) {
+            RomFSSuperblock sb{};
+            if (sizeof(RomFSSuperblock) !=
+                file->ReadObject(&sb, SECTION_HEADER_OFFSET + i * SECTION_HEADER_SIZE))
+                LOG_CRITICAL(Loader, "File reader errored out during header read.");
+
+            const size_t romfs_offset =
+                header.section_tables[i].media_offset * MEDIA_OFFSET_MULTIPLIER +
+                sb.levels[IVFC_MAX_LEVEL - 1].offset;
+            const size_t romfs_size = sb.levels[IVFC_MAX_LEVEL - 1].size;
+            files.emplace_back(std::make_shared<OffsetVfsFile>(file, romfs_size, romfs_offset));
+            romfs = files.back();
+        } else if (block.filesystem_type == NCASectionFilesystemType::PFS0) {
+            PFS0Superblock sb{};
+            // Seek back to beginning of this section.
+            if (sizeof(PFS0Superblock) !=
+                file->ReadObject(&sb, SECTION_HEADER_OFFSET + i * SECTION_HEADER_SIZE))
+                LOG_CRITICAL(Loader, "File reader errored out during header read.");
+
+            u64 offset = (static_cast<u64>(header.section_tables[i].media_offset) *
+                          MEDIA_OFFSET_MULTIPLIER) +
+                         sb.pfs0_header_offset;
+            u64 size = MEDIA_OFFSET_MULTIPLIER * (header.section_tables[i].media_end_offset -
+                                                  header.section_tables[i].media_offset);
+            auto npfs = std::make_shared<PartitionFilesystem>(
+                std::make_shared<OffsetVfsFile>(file, size, offset));
+
+            if (npfs->GetStatus() == Loader::ResultStatus::Success) {
+                dirs.emplace_back(npfs);
+                if (IsDirectoryExeFS(dirs.back()))
+                    exefs = dirs.back();
+            }
+        }
+    }
+
+    status = Loader::ResultStatus::Success;
+}
+
+Loader::ResultStatus NCA::GetStatus() const {
+    return status;
+}
+
+std::vector<std::shared_ptr<VfsFile>> NCA::GetFiles() const {
+    if (status != Loader::ResultStatus::Success)
+        return {};
+    return files;
+}
+
+std::vector<std::shared_ptr<VfsDirectory>> NCA::GetSubdirectories() const {
+    if (status != Loader::ResultStatus::Success)
+        return {};
+    return dirs;
+}
+
+std::string NCA::GetName() const {
+    return file->GetName();
+}
+
+std::shared_ptr<VfsDirectory> NCA::GetParentDirectory() const {
+    return file->GetContainingDirectory();
+}
+
+NCAContentType NCA::GetType() const {
+    return header.content_type;
+}
+
+u64 NCA::GetTitleId() const {
+    if (status != Loader::ResultStatus::Success)
+        return {};
+    return header.title_id;
+}
+
+VirtualFile NCA::GetRomFS() const {
+    return romfs;
+}
+
+VirtualDir NCA::GetExeFS() const {
+    return exefs;
+}
+
+bool NCA::ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) {
+    return false;
+}
+} // namespace FileSys

src/core/file_sys/content_archive.h

@@ -0,0 +1,89 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_funcs.h"
+#include "common/common_types.h"
+#include "common/swap.h"
+#include "core/file_sys/partition_filesystem.h"
+
+namespace FileSys {
+
+enum class NCAContentType : u8 { Program = 0, Meta = 1, Control = 2, Manual = 3, Data = 4 };
+
+struct NCASectionTableEntry {
+    u32_le media_offset;
+    u32_le media_end_offset;
+    INSERT_PADDING_BYTES(0x8);
+};
+static_assert(sizeof(NCASectionTableEntry) == 0x10, "NCASectionTableEntry has incorrect size.");
+
+struct NCAHeader {
+    std::array<u8, 0x100> rsa_signature_1;
+    std::array<u8, 0x100> rsa_signature_2;
+    u32_le magic;
+    u8 is_system;
+    NCAContentType content_type;
+    u8 crypto_type;
+    u8 key_index;
+    u64_le size;
+    u64_le title_id;
+    INSERT_PADDING_BYTES(0x4);
+    u32_le sdk_version;
+    u8 crypto_type_2;
+    INSERT_PADDING_BYTES(15);
+    std::array<u8, 0x10> rights_id;
+    std::array<NCASectionTableEntry, 0x4> section_tables;
+    std::array<std::array<u8, 0x20>, 0x4> hash_tables;
+    std::array<std::array<u8, 0x10>, 0x4> key_area;
+    INSERT_PADDING_BYTES(0xC0);
+};
+static_assert(sizeof(NCAHeader) == 0x400, "NCAHeader has incorrect size.");
+
+static bool IsDirectoryExeFS(std::shared_ptr<FileSys::VfsDirectory> pfs) {
+    // According to switchbrew, an exefs must only contain these two files:
+    return pfs->GetFile("main") != nullptr && pfs->GetFile("main.npdm") != nullptr;
+}
+
+static bool IsValidNCA(const NCAHeader& header) {
+    return header.magic == Common::MakeMagic('N', 'C', 'A', '2') ||
+           header.magic == Common::MakeMagic('N', 'C', 'A', '3');
+}
+
+// An implementation of VfsDirectory that represents a Nintendo Content Archive (NCA) conatiner.
+// After construction, use GetStatus to determine if the file is valid and ready to be used.
+class NCA : public ReadOnlyVfsDirectory {
+public:
+    explicit NCA(VirtualFile file);
+    Loader::ResultStatus GetStatus() const;
+
+    std::vector<std::shared_ptr<VfsFile>> GetFiles() const override;
+    std::vector<std::shared_ptr<VfsDirectory>> GetSubdirectories() const override;
+    std::string GetName() const override;
+    std::shared_ptr<VfsDirectory> GetParentDirectory() const override;
+
+    NCAContentType GetType() const;
+    u64 GetTitleId() const;
+
+    VirtualFile GetRomFS() const;
+    VirtualDir GetExeFS() const;
+
+protected:
+    bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
+
+private:
+    std::vector<VirtualDir> dirs;
+    std::vector<VirtualFile> files;
+
+    VirtualFile romfs = nullptr;
+    VirtualDir exefs = nullptr;
+    VirtualFile file;
+
+    NCAHeader header{};
+
+    Loader::ResultStatus status{};
+};
+
+} // namespace FileSys

src/core/file_sys/disk_filesystem.cpp

@@ -1,237 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#include <cstring>
-#include <memory>
-#include "common/common_types.h"
-#include "common/logging/log.h"
-#include "core/file_sys/disk_filesystem.h"
-#include "core/file_sys/errors.h"
-
-namespace FileSys {
-
-static std::string ModeFlagsToString(Mode mode) {
-    std::string mode_str;
-    u32 mode_flags = static_cast<u32>(mode);
-
-    // Calculate the correct open mode for the file.
-    if ((mode_flags & static_cast<u32>(Mode::Read)) &&
-        (mode_flags & static_cast<u32>(Mode::Write))) {
-        if (mode_flags & static_cast<u32>(Mode::Append))
-            mode_str = "a+";
-        else
-            mode_str = "r+";
-    } else {
-        if (mode_flags & static_cast<u32>(Mode::Read))
-            mode_str = "r";
-        else if (mode_flags & static_cast<u32>(Mode::Append))
-            mode_str = "a";
-        else if (mode_flags & static_cast<u32>(Mode::Write))
-            mode_str = "w";
-    }
-
-    mode_str += "b";
-
-    return mode_str;
-}
-
-std::string Disk_FileSystem::GetName() const {
-    return "Disk";
-}
-
-ResultVal<std::unique_ptr<StorageBackend>> Disk_FileSystem::OpenFile(const std::string& path,
-                                                                     Mode mode) const {
-
-    // Calculate the correct open mode for the file.
-    std::string mode_str = ModeFlagsToString(mode);
-
-    std::string full_path = base_directory + path;
-    auto file = std::make_shared<FileUtil::IOFile>(full_path, mode_str.c_str());
-
-    if (!file->IsOpen()) {
-        return ERROR_PATH_NOT_FOUND;
-    }
-
-    return MakeResult<std::unique_ptr<StorageBackend>>(
-        std::make_unique<Disk_Storage>(std::move(file)));
-}
-
-ResultCode Disk_FileSystem::DeleteFile(const std::string& path) const {
-    if (!FileUtil::Exists(path)) {
-        return ERROR_PATH_NOT_FOUND;
-    }
-
-    FileUtil::Delete(path);
-
-    return RESULT_SUCCESS;
-}
-
-ResultCode Disk_FileSystem::RenameFile(const std::string& src_path,
-                                       const std::string& dest_path) const {
-    const std::string full_src_path = base_directory + src_path;
-    const std::string full_dest_path = base_directory + dest_path;
-
-    if (!FileUtil::Exists(full_src_path)) {
-        return ERROR_PATH_NOT_FOUND;
-    }
-    // TODO(wwylele): Use correct error code
-    return FileUtil::Rename(full_src_path, full_dest_path) ? RESULT_SUCCESS : ResultCode(-1);
-}
-
-ResultCode Disk_FileSystem::DeleteDirectory(const Path& path) const {
-    LOG_WARNING(Service_FS, "(STUBBED) called");
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode Disk_FileSystem::DeleteDirectoryRecursively(const Path& path) const {
-    LOG_WARNING(Service_FS, "(STUBBED) called");
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode Disk_FileSystem::CreateFile(const std::string& path, u64 size) const {
-    LOG_WARNING(Service_FS, "(STUBBED) called");
-
-    std::string full_path = base_directory + path;
-    if (size == 0) {
-        FileUtil::CreateEmptyFile(full_path);
-        return RESULT_SUCCESS;
-    }
-
-    FileUtil::IOFile file(full_path, "wb");
-    // Creates a sparse file (or a normal file on filesystems without the concept of sparse files)
-    // We do this by seeking to the right size, then writing a single null byte.
-    if (file.Seek(size - 1, SEEK_SET) && file.WriteBytes("", 1) == 1) {
-        return RESULT_SUCCESS;
-    }
-
-    LOG_ERROR(Service_FS, "Too large file");
-    // TODO(Subv): Find out the correct error code
-    return ResultCode(-1);
-}
-
-ResultCode Disk_FileSystem::CreateDirectory(const std::string& path) const {
-    // TODO(Subv): Perform path validation to prevent escaping the emulator sandbox.
-    std::string full_path = base_directory + path;
-
-    if (FileUtil::CreateDir(full_path)) {
-        return RESULT_SUCCESS;
-    }
-
-    LOG_CRITICAL(Service_FS, "(unreachable) Unknown error creating {}", full_path);
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode Disk_FileSystem::RenameDirectory(const Path& src_path, const Path& dest_path) const {
-    LOG_WARNING(Service_FS, "(STUBBED) called");
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultVal<std::unique_ptr<DirectoryBackend>> Disk_FileSystem::OpenDirectory(
-    const std::string& path) const {
-
-    std::string full_path = base_directory + path;
-
-    if (!FileUtil::IsDirectory(full_path)) {
-        // TODO(Subv): Find the correct error code for this.
-        return ResultCode(-1);
-    }
-
-    auto directory = std::make_unique<Disk_Directory>(full_path);
-    return MakeResult<std::unique_ptr<DirectoryBackend>>(std::move(directory));
-}
-
-u64 Disk_FileSystem::GetFreeSpaceSize() const {
-    LOG_WARNING(Service_FS, "(STUBBED) called");
-    return 0;
-}
-
-ResultVal<FileSys::EntryType> Disk_FileSystem::GetEntryType(const std::string& path) const {
-    std::string full_path = base_directory + path;
-    if (!FileUtil::Exists(full_path)) {
-        return ERROR_PATH_NOT_FOUND;
-    }
-
-    if (FileUtil::IsDirectory(full_path))
-        return MakeResult(EntryType::Directory);
-
-    return MakeResult(EntryType::File);
-}
-
-ResultVal<size_t> Disk_Storage::Read(const u64 offset, const size_t length, u8* buffer) const {
-    LOG_TRACE(Service_FS, "called offset={}, length={}", offset, length);
-    file->Seek(offset, SEEK_SET);
-    return MakeResult<size_t>(file->ReadBytes(buffer, length));
-}
-
-ResultVal<size_t> Disk_Storage::Write(const u64 offset, const size_t length, const bool flush,
-                                      const u8* buffer) const {
-    LOG_WARNING(Service_FS, "(STUBBED) called");
-    file->Seek(offset, SEEK_SET);
-    size_t written = file->WriteBytes(buffer, length);
-    if (flush) {
-        file->Flush();
-    }
-    return MakeResult<size_t>(written);
-}
-
-u64 Disk_Storage::GetSize() const {
-    return file->GetSize();
-}
-
-bool Disk_Storage::SetSize(const u64 size) const {
-    file->Resize(size);
-    file->Flush();
-    return true;
-}
-
-Disk_Directory::Disk_Directory(const std::string& path) {
-    unsigned size = FileUtil::ScanDirectoryTree(path, directory);
-    directory.size = size;
-    directory.isDirectory = true;
-    children_iterator = directory.children.begin();
-}
-
-u64 Disk_Directory::Read(const u64 count, Entry* entries) {
-    u64 entries_read = 0;
-
-    while (entries_read < count && children_iterator != directory.children.cend()) {
-        const FileUtil::FSTEntry& file = *children_iterator;
-        const std::string& filename = file.virtualName;
-        Entry& entry = entries[entries_read];
-
-        LOG_TRACE(Service_FS, "File {}: size={} dir={}", filename, file.size, file.isDirectory);
-
-        // TODO(Link Mauve): use a proper conversion to UTF-16.
-        for (size_t j = 0; j < FILENAME_LENGTH; ++j) {
-            entry.filename[j] = filename[j];
-            if (!filename[j])
-                break;
-        }
-
-        if (file.isDirectory) {
-            entry.file_size = 0;
-            entry.type = EntryType::Directory;
-        } else {
-            entry.file_size = file.size;
-            entry.type = EntryType::File;
-        }
-
-        ++entries_read;
-        ++children_iterator;
-    }
-    return entries_read;
-}
-
-u64 Disk_Directory::GetEntryCount() const {
-    // We convert the children iterator into a const_iterator to allow template argument deduction
-    // in std::distance.
-    std::vector<FileUtil::FSTEntry>::const_iterator current = children_iterator;
-    return std::distance(current, directory.children.end());
-}
-
-} // namespace FileSys

src/core/file_sys/disk_filesystem.h

@@ -1,84 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#pragma once
-
-#include <cstddef>
-#include <memory>
-#include <string>
-#include "common/common_types.h"
-#include "common/file_util.h"
-#include "core/file_sys/directory.h"
-#include "core/file_sys/filesystem.h"
-#include "core/file_sys/storage.h"
-#include "core/hle/result.h"
-
-namespace FileSys {
-
-class Disk_FileSystem : public FileSystemBackend {
-public:
-    explicit Disk_FileSystem(std::string base_directory)
-        : base_directory(std::move(base_directory)) {}
-
-    std::string GetName() const override;
-
-    ResultVal<std::unique_ptr<StorageBackend>> OpenFile(const std::string& path,
-                                                        Mode mode) const override;
-    ResultCode DeleteFile(const std::string& path) const override;
-    ResultCode RenameFile(const std::string& src_path, const std::string& dest_path) const override;
-    ResultCode DeleteDirectory(const Path& path) const override;
-    ResultCode DeleteDirectoryRecursively(const Path& path) const override;
-    ResultCode CreateFile(const std::string& path, u64 size) const override;
-    ResultCode CreateDirectory(const std::string& path) const override;
-    ResultCode RenameDirectory(const Path& src_path, const Path& dest_path) const override;
-    ResultVal<std::unique_ptr<DirectoryBackend>> OpenDirectory(
-        const std::string& path) const override;
-    u64 GetFreeSpaceSize() const override;
-    ResultVal<EntryType> GetEntryType(const std::string& path) const override;
-
-protected:
-    std::string base_directory;
-};
-
-class Disk_Storage : public StorageBackend {
-public:
-    explicit Disk_Storage(std::shared_ptr<FileUtil::IOFile> file) : file(std::move(file)) {}
-
-    ResultVal<size_t> Read(u64 offset, size_t length, u8* buffer) const override;
-    ResultVal<size_t> Write(u64 offset, size_t length, bool flush, const u8* buffer) const override;
-    u64 GetSize() const override;
-    bool SetSize(u64 size) const override;
-    bool Close() const override {
-        return false;
-    }
-    void Flush() const override {}
-
-private:
-    std::shared_ptr<FileUtil::IOFile> file;
-};
-
-class Disk_Directory : public DirectoryBackend {
-public:
-    explicit Disk_Directory(const std::string& path);
-
-    ~Disk_Directory() override {
-        Close();
-    }
-
-    u64 Read(const u64 count, Entry* entries) override;
-    u64 GetEntryCount() const override;
-
-    bool Close() const override {
-        return true;
-    }
-
-protected:
-    FileUtil::FSTEntry directory;
-
-    // We need to remember the last entry we returned, so a subsequent call to Read will continue
-    // from the next one. This iterator will always point to the next unread entry.
-    std::vector<FileUtil::FSTEntry>::iterator children_iterator;
-};
-
-} // namespace FileSys

src/core/file_sys/filesystem.h

@@ -66,136 +66,4 @@ private:
     std::u16string u16str;
 };
 
-/// Parameters of the archive, as specified in the Create or Format call.
-struct ArchiveFormatInfo {
-    u32_le total_size;         ///< The pre-defined size of the archive.
-    u32_le number_directories; ///< The pre-defined number of directories in the archive.
-    u32_le number_files;       ///< The pre-defined number of files in the archive.
-    u8 duplicate_data;         ///< Whether the archive should duplicate the data.
-};
-static_assert(std::is_pod<ArchiveFormatInfo>::value, "ArchiveFormatInfo is not POD");
-
-class FileSystemBackend : NonCopyable {
-public:
-    virtual ~FileSystemBackend() {}
-
-    /**
-     * Get a descriptive name for the archive (e.g. "RomFS", "SaveData", etc.)
-     */
-    virtual std::string GetName() const = 0;
-
-    /**
-     * Create a file specified by its path
-     * @param path Path relative to the Archive
-     * @param size The size of the new file, filled with zeroes
-     * @return Result of the operation
-     */
-    virtual ResultCode CreateFile(const std::string& path, u64 size) const = 0;
-
-    /**
-     * Delete a file specified by its path
-     * @param path Path relative to the archive
-     * @return Result of the operation
-     */
-    virtual ResultCode DeleteFile(const std::string& path) const = 0;
-
-    /**
-     * Create a directory specified by its path
-     * @param path Path relative to the archive
-     * @return Result of the operation
-     */
-    virtual ResultCode CreateDirectory(const std::string& path) const = 0;
-
-    /**
-     * Delete a directory specified by its path
-     * @param path Path relative to the archive
-     * @return Result of the operation
-     */
-    virtual ResultCode DeleteDirectory(const Path& path) const = 0;
-
-    /**
-     * Delete a directory specified by its path and anything under it
-     * @param path Path relative to the archive
-     * @return Result of the operation
-     */
-    virtual ResultCode DeleteDirectoryRecursively(const Path& path) const = 0;
-
-    /**
-     * Rename a File specified by its path
-     * @param src_path Source path relative to the archive
-     * @param dest_path Destination path relative to the archive
-     * @return Result of the operation
-     */
-    virtual ResultCode RenameFile(const std::string& src_path,
-                                  const std::string& dest_path) const = 0;
-
-    /**
-     * Rename a Directory specified by its path
-     * @param src_path Source path relative to the archive
-     * @param dest_path Destination path relative to the archive
-     * @return Result of the operation
-     */
-    virtual ResultCode RenameDirectory(const Path& src_path, const Path& dest_path) const = 0;
-
-    /**
-     * Open a file specified by its path, using the specified mode
-     * @param path Path relative to the archive
-     * @param mode Mode to open the file with
-     * @return Opened file, or error code
-     */
-    virtual ResultVal<std::unique_ptr<StorageBackend>> OpenFile(const std::string& path,
-                                                                Mode mode) const = 0;
-
-    /**
-     * Open a directory specified by its path
-     * @param path Path relative to the archive
-     * @return Opened directory, or error code
-     */
-    virtual ResultVal<std::unique_ptr<DirectoryBackend>> OpenDirectory(
-        const std::string& path) const = 0;
-
-    /**
-     * Get the free space
-     * @return The number of free bytes in the archive
-     */
-    virtual u64 GetFreeSpaceSize() const = 0;
-
-    /**
-     * Get the type of the specified path
-     * @return The type of the specified path or error code
-     */
-    virtual ResultVal<EntryType> GetEntryType(const std::string& path) const = 0;
-};
-
-class FileSystemFactory : NonCopyable {
-public:
-    virtual ~FileSystemFactory() {}
-
-    /**
-     * Get a descriptive name for the archive (e.g. "RomFS", "SaveData", etc.)
-     */
-    virtual std::string GetName() const = 0;
-
-    /**
-     * Tries to open the archive of this type with the specified path
-     * @param path Path to the archive
-     * @return An ArchiveBackend corresponding operating specified archive path.
-     */
-    virtual ResultVal<std::unique_ptr<FileSystemBackend>> Open(const Path& path) = 0;
-
-    /**
-     * Deletes the archive contents and then re-creates the base folder
-     * @param path Path to the archive
-     * @return ResultCode of the operation, 0 on success
-     */
-    virtual ResultCode Format(const Path& path) = 0;
-
-    /**
-     * Retrieves the format info about the archive with the specified path
-     * @param path Path to the archive
-     * @return Format information about the archive or error code
-     */
-    virtual ResultVal<ArchiveFormatInfo> GetFormatInfo(const Path& path) const = 0;
-};
-
 } // namespace FileSys

src/core/file_sys/partition_filesystem.cpp

@@ -6,29 +6,30 @@
 #include "common/file_util.h"
 #include "common/logging/log.h"
 #include "core/file_sys/partition_filesystem.h"
+#include "core/file_sys/vfs_offset.h"
 #include "core/loader/loader.h"
 
 namespace FileSys {
 
-Loader::ResultStatus PartitionFilesystem::Load(const std::string& file_path, size_t offset) {
-    FileUtil::IOFile file(file_path, "rb");
-    if (!file.IsOpen())
-        return Loader::ResultStatus::Error;
-
+PartitionFilesystem::PartitionFilesystem(std::shared_ptr<VfsFile> file) {
     // At least be as large as the header
-    if (file.GetSize() < sizeof(Header))
-        return Loader::ResultStatus::Error;
+    if (file->GetSize() < sizeof(Header)) {
+        status = Loader::ResultStatus::Error;
+        return;
+    }
 
-    file.Seek(offset, SEEK_SET);
     // For cartridges, HFSs can get very large, so we need to calculate the size up to
     // the actual content itself instead of just blindly reading in the entire file.
     Header pfs_header;
-    if (!file.ReadBytes(&pfs_header, sizeof(Header)))
-        return Loader::ResultStatus::Error;
+    if (sizeof(Header) != file->ReadObject(&pfs_header)) {
+        status = Loader::ResultStatus::Error;
+        return;
+    }
 
     if (pfs_header.magic != Common::MakeMagic('H', 'F', 'S', '0') &&
         pfs_header.magic != Common::MakeMagic('P', 'F', 'S', '0')) {
-        return Loader::ResultStatus::ErrorInvalidFormat;
+        status = Loader::ResultStatus::ErrorInvalidFormat;
+        return;
     }
 
     bool is_hfs = pfs_header.magic == Common::MakeMagic('H', 'F', 'S', '0');
@@ -38,99 +39,86 @@ Loader::ResultStatus PartitionFilesystem::Load(const std::string& file_path, siz
         sizeof(Header) + (pfs_header.num_entries * entry_size) + pfs_header.strtab_size;
 
     // Actually read in now...
-    file.Seek(offset, SEEK_SET);
-    std::vector<u8> file_data(metadata_size);
-
-    if (!file.ReadBytes(file_data.data(), metadata_size))
-        return Loader::ResultStatus::Error;
+    std::vector<u8> file_data = file->ReadBytes(metadata_size);
 
-    Loader::ResultStatus result = Load(file_data);
-    if (result != Loader::ResultStatus::Success)
-        LOG_ERROR(Service_FS, "Failed to load PFS from file {}!", file_path);
-
-    return result;
-}
+    if (file_data.size() != metadata_size) {
+        status = Loader::ResultStatus::Error;
+        return;
+    }
 
-Loader::ResultStatus PartitionFilesystem::Load(const std::vector<u8>& file_data, size_t offset) {
-    size_t total_size = file_data.size() - offset;
-    if (total_size < sizeof(Header))
-        return Loader::ResultStatus::Error;
+    size_t total_size = file_data.size();
+    if (total_size < sizeof(Header)) {
+        status = Loader::ResultStatus::Error;
+        return;
+    }
 
-    memcpy(&pfs_header, &file_data[offset], sizeof(Header));
+    memcpy(&pfs_header, file_data.data(), sizeof(Header));
     if (pfs_header.magic != Common::MakeMagic('H', 'F', 'S', '0') &&
         pfs_header.magic != Common::MakeMagic('P', 'F', 'S', '0')) {
-        return Loader::ResultStatus::ErrorInvalidFormat;
+        status = Loader::ResultStatus::ErrorInvalidFormat;
+        return;
     }
 
     is_hfs = pfs_header.magic == Common::MakeMagic('H', 'F', 'S', '0');
 
-    size_t entries_offset = offset + sizeof(Header);
-    size_t entry_size = is_hfs ? sizeof(HFSEntry) : sizeof(PFSEntry);
+    size_t entries_offset = sizeof(Header);
     size_t strtab_offset = entries_offset + (pfs_header.num_entries * entry_size);
+    content_offset = strtab_offset + pfs_header.strtab_size;
     for (u16 i = 0; i < pfs_header.num_entries; i++) {
-        FileEntry entry;
+        FSEntry entry;
 
-        memcpy(&entry.fs_entry, &file_data[entries_offset + (i * entry_size)], sizeof(FSEntry));
-        entry.name = std::string(reinterpret_cast<const char*>(
-            &file_data[strtab_offset + entry.fs_entry.strtab_offset]));
-        pfs_entries.push_back(std::move(entry));
-    }
+        memcpy(&entry, &file_data[entries_offset + (i * entry_size)], sizeof(FSEntry));
+        std::string name(
+            reinterpret_cast<const char*>(&file_data[strtab_offset + entry.strtab_offset]));
 
-    content_offset = strtab_offset + pfs_header.strtab_size;
+        pfs_files.emplace_back(
+            std::make_shared<OffsetVfsFile>(file, entry.size, content_offset + entry.offset, name));
+    }
 
-    return Loader::ResultStatus::Success;
+    status = Loader::ResultStatus::Success;
 }
 
-u32 PartitionFilesystem::GetNumEntries() const {
-    return pfs_header.num_entries;
+Loader::ResultStatus PartitionFilesystem::GetStatus() const {
+    return status;
 }
 
-u64 PartitionFilesystem::GetEntryOffset(u32 index) const {
-    if (index > GetNumEntries())
-        return 0;
-
-    return content_offset + pfs_entries[index].fs_entry.offset;
+std::vector<std::shared_ptr<VfsFile>> PartitionFilesystem::GetFiles() const {
+    return pfs_files;
 }
 
-u64 PartitionFilesystem::GetEntrySize(u32 index) const {
-    if (index > GetNumEntries())
-        return 0;
-
-    return pfs_entries[index].fs_entry.size;
+std::vector<std::shared_ptr<VfsDirectory>> PartitionFilesystem::GetSubdirectories() const {
+    return {};
 }
 
-std::string PartitionFilesystem::GetEntryName(u32 index) const {
-    if (index > GetNumEntries())
-        return "";
+std::string PartitionFilesystem::GetName() const {
+    return is_hfs ? "HFS0" : "PFS0";
+}
 
-    return pfs_entries[index].name;
+std::shared_ptr<VfsDirectory> PartitionFilesystem::GetParentDirectory() const {
+    // TODO(DarkLordZach): Add support for nested containers.
+    return nullptr;
 }
 
-u64 PartitionFilesystem::GetFileOffset(const std::string& name) const {
+void PartitionFilesystem::PrintDebugInfo() const {
+    LOG_DEBUG(Service_FS, "Magic:                  {:.4}", pfs_header.magic);
+    LOG_DEBUG(Service_FS, "Files:                  {}", pfs_header.num_entries);
     for (u32 i = 0; i < pfs_header.num_entries; i++) {
-        if (pfs_entries[i].name == name)
-            return content_offset + pfs_entries[i].fs_entry.offset;
+        LOG_DEBUG(Service_FS, " > File {}:              {} (0x{:X} bytes, at 0x{:X})", i,
+                  pfs_files[i]->GetName(), pfs_files[i]->GetSize(),
+                  dynamic_cast<OffsetVfsFile*>(pfs_files[i].get())->GetOffset());
     }
-
-    return 0;
 }
 
-u64 PartitionFilesystem::GetFileSize(const std::string& name) const {
-    for (u32 i = 0; i < pfs_header.num_entries; i++) {
-        if (pfs_entries[i].name == name)
-            return pfs_entries[i].fs_entry.size;
-    }
+bool PartitionFilesystem::ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) {
+    auto iter = std::find(pfs_files.begin(), pfs_files.end(), file);
+    if (iter == pfs_files.end())
+        return false;
 
-    return 0;
-}
+    pfs_files[iter - pfs_files.begin()] = pfs_files.back();
+    pfs_files.pop_back();
 
-void PartitionFilesystem::Print() const {
-    LOG_DEBUG(Service_FS, "Magic:                  {}", pfs_header.magic);
-    LOG_DEBUG(Service_FS, "Files:                  {}", pfs_header.num_entries);
-    for (u32 i = 0; i < pfs_header.num_entries; i++) {
-        LOG_DEBUG(Service_FS, " > File {}:              {} (0x{:X} bytes, at 0x{:X})", i,
-                  pfs_entries[i].name.c_str(), pfs_entries[i].fs_entry.size,
-                  GetFileOffset(pfs_entries[i].name));
-    }
+    pfs_dirs.emplace_back(dir);
+
+    return true;
 }
 } // namespace FileSys

src/core/file_sys/partition_filesystem.h

@@ -10,6 +10,7 @@
 #include "common/common_funcs.h"
 #include "common/common_types.h"
 #include "common/swap.h"
+#include "core/file_sys/vfs.h"
 
 namespace Loader {
 enum class ResultStatus;
@@ -21,19 +22,19 @@ namespace FileSys {
  * Helper which implements an interface to parse PFS/HFS filesystems.
  * Data can either be loaded from a file path or data with an offset into it.
  */
-class PartitionFilesystem {
+class PartitionFilesystem : public ReadOnlyVfsDirectory {
 public:
-    Loader::ResultStatus Load(const std::string& file_path, size_t offset = 0);
-    Loader::ResultStatus Load(const std::vector<u8>& file_data, size_t offset = 0);
+    explicit PartitionFilesystem(std::shared_ptr<VfsFile> file);
+    Loader::ResultStatus GetStatus() const;
 
-    u32 GetNumEntries() const;
-    u64 GetEntryOffset(u32 index) const;
-    u64 GetEntrySize(u32 index) const;
-    std::string GetEntryName(u32 index) const;
-    u64 GetFileOffset(const std::string& name) const;
-    u64 GetFileSize(const std::string& name) const;
+    std::vector<std::shared_ptr<VfsFile>> GetFiles() const override;
+    std::vector<std::shared_ptr<VfsDirectory>> GetSubdirectories() const override;
+    std::string GetName() const override;
+    std::shared_ptr<VfsDirectory> GetParentDirectory() const override;
+    void PrintDebugInfo() const;
 
-    void Print() const;
+protected:
+    bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
 
 private:
     struct Header {
@@ -72,16 +73,14 @@ private:
 
 #pragma pack(pop)
 
-    struct FileEntry {
-        FSEntry fs_entry;
-        std::string name;
-    };
+    Loader::ResultStatus status;
 
     Header pfs_header;
     bool is_hfs;
     size_t content_offset;
 
-    std::vector<FileEntry> pfs_entries;
+    std::vector<VirtualFile> pfs_files;
+    std::vector<VirtualDir> pfs_dirs;
 };
 
 } // namespace FileSys

src/core/file_sys/program_metadata.cpp

@@ -9,40 +9,29 @@
 
 namespace FileSys {
 
-Loader::ResultStatus ProgramMetadata::Load(const std::string& file_path) {
-    FileUtil::IOFile file(file_path, "rb");
-    if (!file.IsOpen())
+Loader::ResultStatus ProgramMetadata::Load(VirtualFile file) {
+    size_t total_size = static_cast<size_t>(file->GetSize());
+    if (total_size < sizeof(Header))
         return Loader::ResultStatus::Error;
 
-    std::vector<u8> file_data(file.GetSize());
-
-    if (!file.ReadBytes(file_data.data(), file_data.size()))
+    // TODO(DarkLordZach): Use ReadObject when Header/AcidHeader becomes trivially copyable.
+    std::vector<u8> npdm_header_data = file->ReadBytes(sizeof(Header));
+    if (sizeof(Header) != npdm_header_data.size())
         return Loader::ResultStatus::Error;
+    std::memcpy(&npdm_header, npdm_header_data.data(), sizeof(Header));
 
-    Loader::ResultStatus result = Load(file_data);
-    if (result != Loader::ResultStatus::Success)
-        LOG_ERROR(Service_FS, "Failed to load NPDM from file {}!", file_path);
-
-    return result;
-}
-
-Loader::ResultStatus ProgramMetadata::Load(const std::vector<u8> file_data, size_t offset) {
-    size_t total_size = static_cast<size_t>(file_data.size() - offset);
-    if (total_size < sizeof(Header))
+    std::vector<u8> acid_header_data = file->ReadBytes(sizeof(AcidHeader), npdm_header.acid_offset);
+    if (sizeof(AcidHeader) != acid_header_data.size())
         return Loader::ResultStatus::Error;
+    std::memcpy(&acid_header, acid_header_data.data(), sizeof(AcidHeader));
 
-    size_t header_offset = offset;
-    memcpy(&npdm_header, &file_data[offset], sizeof(Header));
-
-    size_t aci_offset = header_offset + npdm_header.aci_offset;
-    size_t acid_offset = header_offset + npdm_header.acid_offset;
-    memcpy(&aci_header, &file_data[aci_offset], sizeof(AciHeader));
-    memcpy(&acid_header, &file_data[acid_offset], sizeof(AcidHeader));
+    if (sizeof(AciHeader) != file->ReadObject(&aci_header, npdm_header.aci_offset))
+        return Loader::ResultStatus::Error;
 
-    size_t fac_offset = acid_offset + acid_header.fac_offset;
-    size_t fah_offset = aci_offset + aci_header.fah_offset;
-    memcpy(&acid_file_access, &file_data[fac_offset], sizeof(FileAccessControl));
-    memcpy(&aci_file_access, &file_data[fah_offset], sizeof(FileAccessHeader));
+    if (sizeof(FileAccessControl) != file->ReadObject(&acid_file_access, acid_header.fac_offset))
+        return Loader::ResultStatus::Error;
+    if (sizeof(FileAccessHeader) != file->ReadObject(&aci_file_access, aci_header.fah_offset))
+        return Loader::ResultStatus::Error;
 
     return Loader::ResultStatus::Success;
 }

src/core/file_sys/program_metadata.h

@@ -10,6 +10,7 @@
 #include "common/bit_field.h"
 #include "common/common_types.h"
 #include "common/swap.h"
+#include "partition_filesystem.h"
 
 namespace Loader {
 enum class ResultStatus;
@@ -37,8 +38,7 @@ enum class ProgramFilePermission : u64 {
  */
 class ProgramMetadata {
 public:
-    Loader::ResultStatus Load(const std::string& file_path);
-    Loader::ResultStatus Load(const std::vector<u8> file_data, size_t offset = 0);
+    Loader::ResultStatus Load(VirtualFile file);
 
     bool Is64BitProgram() const;
     ProgramAddressSpaceType GetAddressSpaceType() const;
@@ -51,6 +51,7 @@ public:
     void Print() const;
 
 private:
+    // TODO(DarkLordZach): BitField is not trivially copyable.
     struct Header {
         std::array<char, 4> magic;
         std::array<u8, 8> reserved;
@@ -77,6 +78,7 @@ private:
 
     static_assert(sizeof(Header) == 0x80, "NPDM header structure size is wrong");
 
+    // TODO(DarkLordZach): BitField is not trivially copyable.
     struct AcidHeader {
         std::array<u8, 0x100> signature;
         std::array<u8, 0x100> nca_modulus;

src/core/file_sys/romfs_factory.cpp

@@ -1,38 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#include <algorithm>
-#include <memory>
-#include "common/common_types.h"
-#include "common/logging/log.h"
-#include "core/file_sys/romfs_factory.h"
-#include "core/file_sys/romfs_filesystem.h"
-
-namespace FileSys {
-
-RomFS_Factory::RomFS_Factory(Loader::AppLoader& app_loader) {
-    // Load the RomFS from the app
-    if (Loader::ResultStatus::Success != app_loader.ReadRomFS(romfs_file, data_offset, data_size)) {
-        LOG_ERROR(Service_FS, "Unable to read RomFS!");
-    }
-}
-
-ResultVal<std::unique_ptr<FileSystemBackend>> RomFS_Factory::Open(const Path& path) {
-    auto archive = std::make_unique<RomFS_FileSystem>(romfs_file, data_offset, data_size);
-    return MakeResult<std::unique_ptr<FileSystemBackend>>(std::move(archive));
-}
-
-ResultCode RomFS_Factory::Format(const Path& path) {
-    LOG_ERROR(Service_FS, "Unimplemented Format archive {}", GetName());
-    // TODO(bunnei): Find the right error code for this
-    return ResultCode(-1);
-}
-
-ResultVal<ArchiveFormatInfo> RomFS_Factory::GetFormatInfo(const Path& path) const {
-    LOG_ERROR(Service_FS, "Unimplemented GetFormatInfo archive {}", GetName());
-    // TODO(bunnei): Find the right error code for this
-    return ResultCode(-1);
-}
-
-} // namespace FileSys

src/core/file_sys/romfs_factory.h

@@ -1,35 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#pragma once
-
-#include <memory>
-#include <string>
-#include <vector>
-#include "common/common_types.h"
-#include "core/file_sys/filesystem.h"
-#include "core/hle/result.h"
-#include "core/loader/loader.h"
-
-namespace FileSys {
-
-/// File system interface to the RomFS archive
-class RomFS_Factory final : public FileSystemFactory {
-public:
-    explicit RomFS_Factory(Loader::AppLoader& app_loader);
-
-    std::string GetName() const override {
-        return "ArchiveFactory_RomFS";
-    }
-    ResultVal<std::unique_ptr<FileSystemBackend>> Open(const Path& path) override;
-    ResultCode Format(const Path& path) override;
-    ResultVal<ArchiveFormatInfo> GetFormatInfo(const Path& path) const override;
-
-private:
-    std::shared_ptr<FileUtil::IOFile> romfs_file;
-    u64 data_offset;
-    u64 data_size;
-};
-
-} // namespace FileSys

src/core/file_sys/romfs_filesystem.cpp

@@ -1,110 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#include <cstring>
-#include <memory>
-#include "common/common_types.h"
-#include "common/logging/log.h"
-#include "core/file_sys/romfs_filesystem.h"
-
-namespace FileSys {
-
-std::string RomFS_FileSystem::GetName() const {
-    return "RomFS";
-}
-
-ResultVal<std::unique_ptr<StorageBackend>> RomFS_FileSystem::OpenFile(const std::string& path,
-                                                                      Mode mode) const {
-    return MakeResult<std::unique_ptr<StorageBackend>>(
-        std::make_unique<RomFS_Storage>(romfs_file, data_offset, data_size));
-}
-
-ResultCode RomFS_FileSystem::DeleteFile(const std::string& path) const {
-    LOG_CRITICAL(Service_FS, "Attempted to delete a file from an ROMFS archive ({}).", GetName());
-    // TODO(bunnei): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode RomFS_FileSystem::RenameFile(const std::string& src_path,
-                                        const std::string& dest_path) const {
-    LOG_CRITICAL(Service_FS, "Attempted to rename a file within an ROMFS archive ({}).", GetName());
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode RomFS_FileSystem::DeleteDirectory(const Path& path) const {
-    LOG_CRITICAL(Service_FS, "Attempted to delete a directory from an ROMFS archive ({}).",
-                 GetName());
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode RomFS_FileSystem::DeleteDirectoryRecursively(const Path& path) const {
-    LOG_CRITICAL(Service_FS, "Attempted to delete a directory from an ROMFS archive ({}).",
-                 GetName());
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode RomFS_FileSystem::CreateFile(const std::string& path, u64 size) const {
-    LOG_CRITICAL(Service_FS, "Attempted to create a file in an ROMFS archive ({}).", GetName());
-    // TODO(bunnei): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode RomFS_FileSystem::CreateDirectory(const std::string& path) const {
-    LOG_CRITICAL(Service_FS, "Attempted to create a directory in an ROMFS archive ({}).",
-                 GetName());
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultCode RomFS_FileSystem::RenameDirectory(const Path& src_path, const Path& dest_path) const {
-    LOG_CRITICAL(Service_FS, "Attempted to rename a file within an ROMFS archive ({}).", GetName());
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultVal<std::unique_ptr<DirectoryBackend>> RomFS_FileSystem::OpenDirectory(
-    const std::string& path) const {
-    LOG_WARNING(Service_FS, "Opening Directory in a ROMFS archive");
-    return MakeResult<std::unique_ptr<DirectoryBackend>>(std::make_unique<ROMFSDirectory>());
-}
-
-u64 RomFS_FileSystem::GetFreeSpaceSize() const {
-    LOG_WARNING(Service_FS, "Attempted to get the free space in an ROMFS archive");
-    return 0;
-}
-
-ResultVal<FileSys::EntryType> RomFS_FileSystem::GetEntryType(const std::string& path) const {
-    LOG_CRITICAL(Service_FS, "Called within an ROMFS archive (path {}).", path);
-    // TODO(wwylele): Use correct error code
-    return ResultCode(-1);
-}
-
-ResultVal<size_t> RomFS_Storage::Read(const u64 offset, const size_t length, u8* buffer) const {
-    LOG_TRACE(Service_FS, "called offset={}, length={}", offset, length);
-    romfs_file->Seek(data_offset + offset, SEEK_SET);
-    size_t read_length = (size_t)std::min((u64)length, data_size - offset);
-
-    return MakeResult<size_t>(romfs_file->ReadBytes(buffer, read_length));
-}
-
-ResultVal<size_t> RomFS_Storage::Write(const u64 offset, const size_t length, const bool flush,
-                                       const u8* buffer) const {
-    LOG_ERROR(Service_FS, "Attempted to write to ROMFS file");
-    // TODO(Subv): Find error code
-    return MakeResult<size_t>(0);
-}
-
-u64 RomFS_Storage::GetSize() const {
-    return data_size;
-}
-
-bool RomFS_Storage::SetSize(const u64 size) const {
-    LOG_ERROR(Service_FS, "Attempted to set the size of an ROMFS file");
-    return false;
-}
-
-} // namespace FileSys

src/core/file_sys/romfs_filesystem.h

@@ -1,85 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#pragma once
-
-#include <cstddef>
-#include <memory>
-#include <string>
-#include <vector>
-#include "common/common_types.h"
-#include "common/file_util.h"
-#include "core/file_sys/directory.h"
-#include "core/file_sys/filesystem.h"
-#include "core/file_sys/storage.h"
-#include "core/hle/result.h"
-
-namespace FileSys {
-
-/**
- * Helper which implements an interface to deal with Switch .istorage ROMFS images used in some
- * archives This should be subclassed by concrete archive types, which will provide the input data
- * (load the raw ROMFS archive) and override any required methods
- */
-class RomFS_FileSystem : public FileSystemBackend {
-public:
-    RomFS_FileSystem(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size)
-        : romfs_file(file), data_offset(offset), data_size(size) {}
-
-    std::string GetName() const override;
-
-    ResultVal<std::unique_ptr<StorageBackend>> OpenFile(const std::string& path,
-                                                        Mode mode) const override;
-    ResultCode DeleteFile(const std::string& path) const override;
-    ResultCode RenameFile(const std::string& src_path, const std::string& dest_path) const override;
-    ResultCode DeleteDirectory(const Path& path) const override;
-    ResultCode DeleteDirectoryRecursively(const Path& path) const override;
-    ResultCode CreateFile(const std::string& path, u64 size) const override;
-    ResultCode CreateDirectory(const std::string& path) const override;
-    ResultCode RenameDirectory(const Path& src_path, const Path& dest_path) const override;
-    ResultVal<std::unique_ptr<DirectoryBackend>> OpenDirectory(
-        const std::string& path) const override;
-    u64 GetFreeSpaceSize() const override;
-    ResultVal<EntryType> GetEntryType(const std::string& path) const override;
-
-protected:
-    std::shared_ptr<FileUtil::IOFile> romfs_file;
-    u64 data_offset;
-    u64 data_size;
-};
-
-class RomFS_Storage : public StorageBackend {
-public:
-    RomFS_Storage(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size)
-        : romfs_file(file), data_offset(offset), data_size(size) {}
-
-    ResultVal<size_t> Read(u64 offset, size_t length, u8* buffer) const override;
-    ResultVal<size_t> Write(u64 offset, size_t length, bool flush, const u8* buffer) const override;
-    u64 GetSize() const override;
-    bool SetSize(u64 size) const override;
-    bool Close() const override {
-        return false;
-    }
-    void Flush() const override {}
-
-private:
-    std::shared_ptr<FileUtil::IOFile> romfs_file;
-    u64 data_offset;
-    u64 data_size;
-};
-
-class ROMFSDirectory : public DirectoryBackend {
-public:
-    u64 Read(const u64 count, Entry* entries) override {
-        return 0;
-    }
-    u64 GetEntryCount() const override {
-        return 0;
-    }
-    bool Close() const override {
-        return false;
-    }
-};
-
-} // namespace FileSys

src/core/file_sys/savedata_factory.cpp

@@ -1,54 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#include <memory>
-#include "common/common_types.h"
-#include "common/logging/log.h"
-#include "core/core.h"
-#include "core/file_sys/disk_filesystem.h"
-#include "core/file_sys/savedata_factory.h"
-#include "core/hle/kernel/process.h"
-
-namespace FileSys {
-
-SaveData_Factory::SaveData_Factory(std::string nand_directory)
-    : nand_directory(std::move(nand_directory)) {}
-
-ResultVal<std::unique_ptr<FileSystemBackend>> SaveData_Factory::Open(const Path& path) {
-    std::string save_directory = GetFullPath();
-    // Return an error if the save data doesn't actually exist.
-    if (!FileUtil::IsDirectory(save_directory)) {
-        // TODO(Subv): Find out correct error code.
-        return ResultCode(-1);
-    }
-
-    auto archive = std::make_unique<Disk_FileSystem>(save_directory);
-    return MakeResult<std::unique_ptr<FileSystemBackend>>(std::move(archive));
-}
-
-ResultCode SaveData_Factory::Format(const Path& path) {
-    LOG_WARNING(Service_FS, "Format archive {}", GetName());
-    // Create the save data directory.
-    if (!FileUtil::CreateFullPath(GetFullPath())) {
-        // TODO(Subv): Find the correct error code.
-        return ResultCode(-1);
-    }
-
-    return RESULT_SUCCESS;
-}
-
-ResultVal<ArchiveFormatInfo> SaveData_Factory::GetFormatInfo(const Path& path) const {
-    LOG_ERROR(Service_FS, "Unimplemented GetFormatInfo archive {}", GetName());
-    // TODO(bunnei): Find the right error code for this
-    return ResultCode(-1);
-}
-
-std::string SaveData_Factory::GetFullPath() const {
-    u64 title_id = Core::CurrentProcess()->program_id;
-    // TODO(Subv): Somehow obtain this value.
-    u32 user = 0;
-    return fmt::format("{}save/{:016X}/{:08X}/", nand_directory, title_id, user);
-}
-
-} // namespace FileSys

src/core/file_sys/savedata_factory.h

@@ -1,33 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#pragma once
-
-#include <memory>
-#include <string>
-#include "common/common_types.h"
-#include "core/file_sys/filesystem.h"
-#include "core/hle/result.h"
-
-namespace FileSys {
-
-/// File system interface to the SaveData archive
-class SaveData_Factory final : public FileSystemFactory {
-public:
-    explicit SaveData_Factory(std::string nand_directory);
-
-    std::string GetName() const override {
-        return "SaveData_Factory";
-    }
-    ResultVal<std::unique_ptr<FileSystemBackend>> Open(const Path& path) override;
-    ResultCode Format(const Path& path) override;
-    ResultVal<ArchiveFormatInfo> GetFormatInfo(const Path& path) const override;
-
-private:
-    std::string nand_directory;
-
-    std::string GetFullPath() const;
-};
-
-} // namespace FileSys

src/core/file_sys/sdmc_factory.cpp

@@ -1,39 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#include <memory>
-#include "common/common_types.h"
-#include "common/logging/log.h"
-#include "common/string_util.h"
-#include "core/core.h"
-#include "core/file_sys/disk_filesystem.h"
-#include "core/file_sys/sdmc_factory.h"
-
-namespace FileSys {
-
-SDMC_Factory::SDMC_Factory(std::string sd_directory) : sd_directory(std::move(sd_directory)) {}
-
-ResultVal<std::unique_ptr<FileSystemBackend>> SDMC_Factory::Open(const Path& path) {
-    // Create the SD Card directory if it doesn't already exist.
-    if (!FileUtil::IsDirectory(sd_directory)) {
-        FileUtil::CreateFullPath(sd_directory);
-    }
-
-    auto archive = std::make_unique<Disk_FileSystem>(sd_directory);
-    return MakeResult<std::unique_ptr<FileSystemBackend>>(std::move(archive));
-}
-
-ResultCode SDMC_Factory::Format(const Path& path) {
-    LOG_ERROR(Service_FS, "Unimplemented Format archive {}", GetName());
-    // TODO(Subv): Find the right error code for this
-    return ResultCode(-1);
-}
-
-ResultVal<ArchiveFormatInfo> SDMC_Factory::GetFormatInfo(const Path& path) const {
-    LOG_ERROR(Service_FS, "Unimplemented GetFormatInfo archive {}", GetName());
-    // TODO(bunnei): Find the right error code for this
-    return ResultCode(-1);
-}
-
-} // namespace FileSys

src/core/file_sys/sdmc_factory.h

@@ -1,31 +0,0 @@
-// Copyright 2018 yuzu emulator team
-// Licensed under GPLv2 or any later version
-// Refer to the license.txt file included.
-
-#pragma once
-
-#include <memory>
-#include <string>
-#include "common/common_types.h"
-#include "core/file_sys/filesystem.h"
-#include "core/hle/result.h"
-
-namespace FileSys {
-
-/// File system interface to the SDCard archive
-class SDMC_Factory final : public FileSystemFactory {
-public:
-    explicit SDMC_Factory(std::string sd_directory);
-
-    std::string GetName() const override {
-        return "SDMC_Factory";
-    }
-    ResultVal<std::unique_ptr<FileSystemBackend>> Open(const Path& path) override;
-    ResultCode Format(const Path& path) override;
-    ResultVal<ArchiveFormatInfo> GetFormatInfo(const Path& path) const override;
-
-private:
-    std::string sd_directory;
-};
-
-} // namespace FileSys

src/core/file_sys/vfs.cpp

@@ -0,0 +1,187 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <numeric>
+#include "common/file_util.h"
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+VfsFile::~VfsFile() = default;
+
+std::string VfsFile::GetExtension() const {
+    return FileUtil::GetExtensionFromFilename(GetName());
+}
+
+VfsDirectory::~VfsDirectory() = default;
+
+boost::optional<u8> VfsFile::ReadByte(size_t offset) const {
+    u8 out{};
+    size_t size = Read(&out, 1, offset);
+    if (size == 1)
+        return out;
+
+    return boost::none;
+}
+
+std::vector<u8> VfsFile::ReadBytes(size_t size, size_t offset) const {
+    std::vector<u8> out(size);
+    size_t read_size = Read(out.data(), size, offset);
+    out.resize(read_size);
+    return out;
+}
+
+std::vector<u8> VfsFile::ReadAllBytes() const {
+    return ReadBytes(GetSize());
+}
+
+bool VfsFile::WriteByte(u8 data, size_t offset) {
+    return Write(&data, 1, offset) == 1;
+}
+
+size_t VfsFile::WriteBytes(std::vector<u8> data, size_t offset) {
+    return Write(data.data(), data.size(), offset);
+}
+
+std::shared_ptr<VfsFile> VfsDirectory::GetFileRelative(const std::string& path) const {
+    auto vec = FileUtil::SplitPathComponents(path);
+    vec.erase(std::remove_if(vec.begin(), vec.end(), [](const auto& str) { return str.empty(); }),
+              vec.end());
+    if (vec.empty())
+        return nullptr;
+    if (vec.size() == 1)
+        return GetFile(vec[0]);
+    auto dir = GetSubdirectory(vec[0]);
+    for (size_t i = 1; i < vec.size() - 1; ++i) {
+        if (dir == nullptr)
+            return nullptr;
+        dir = dir->GetSubdirectory(vec[i]);
+    }
+    if (dir == nullptr)
+        return nullptr;
+    return dir->GetFile(vec.back());
+}
+
+std::shared_ptr<VfsFile> VfsDirectory::GetFileAbsolute(const std::string& path) const {
+    if (IsRoot())
+        return GetFileRelative(path);
+
+    return GetParentDirectory()->GetFileAbsolute(path);
+}
+
+std::shared_ptr<VfsDirectory> VfsDirectory::GetDirectoryRelative(const std::string& path) const {
+    auto vec = FileUtil::SplitPathComponents(path);
+    vec.erase(std::remove_if(vec.begin(), vec.end(), [](const auto& str) { return str.empty(); }),
+              vec.end());
+    if (vec.empty())
+        // return std::shared_ptr<VfsDirectory>(this);
+        return nullptr;
+    auto dir = GetSubdirectory(vec[0]);
+    for (size_t i = 1; i < vec.size(); ++i) {
+        dir = dir->GetSubdirectory(vec[i]);
+    }
+    return dir;
+}
+
+std::shared_ptr<VfsDirectory> VfsDirectory::GetDirectoryAbsolute(const std::string& path) const {
+    if (IsRoot())
+        return GetDirectoryRelative(path);
+
+    return GetParentDirectory()->GetDirectoryAbsolute(path);
+}
+
+std::shared_ptr<VfsFile> VfsDirectory::GetFile(const std::string& name) const {
+    const auto& files = GetFiles();
+    const auto iter = std::find_if(files.begin(), files.end(),
+                                   [&name](const auto& file1) { return name == file1->GetName(); });
+    return iter == files.end() ? nullptr : *iter;
+}
+
+std::shared_ptr<VfsDirectory> VfsDirectory::GetSubdirectory(const std::string& name) const {
+    const auto& subs = GetSubdirectories();
+    const auto iter = std::find_if(subs.begin(), subs.end(),
+                                   [&name](const auto& file1) { return name == file1->GetName(); });
+    return iter == subs.end() ? nullptr : *iter;
+}
+
+bool VfsDirectory::IsRoot() const {
+    return GetParentDirectory() == nullptr;
+}
+
+size_t VfsDirectory::GetSize() const {
+    const auto& files = GetFiles();
+    const auto file_total =
+        std::accumulate(files.begin(), files.end(), 0ull,
+                        [](const auto& f1, const auto& f2) { return f1 + f2->GetSize(); });
+
+    const auto& sub_dir = GetSubdirectories();
+    const auto subdir_total =
+        std::accumulate(sub_dir.begin(), sub_dir.end(), 0ull,
+                        [](const auto& f1, const auto& f2) { return f1 + f2->GetSize(); });
+
+    return file_total + subdir_total;
+}
+
+bool VfsDirectory::DeleteSubdirectoryRecursive(const std::string& name) {
+    auto dir = GetSubdirectory(name);
+    if (dir == nullptr)
+        return false;
+
+    bool success = true;
+    for (const auto& file : dir->GetFiles()) {
+        if (!DeleteFile(file->GetName()))
+            success = false;
+    }
+
+    for (const auto& sdir : dir->GetSubdirectories()) {
+        if (!dir->DeleteSubdirectoryRecursive(sdir->GetName()))
+            success = false;
+    }
+
+    return success;
+}
+
+bool VfsDirectory::Copy(const std::string& src, const std::string& dest) {
+    const auto f1 = GetFile(src);
+    auto f2 = CreateFile(dest);
+    if (f1 == nullptr || f2 == nullptr)
+        return false;
+
+    if (!f2->Resize(f1->GetSize())) {
+        DeleteFile(dest);
+        return false;
+    }
+
+    return f2->WriteBytes(f1->ReadAllBytes()) == f1->GetSize();
+}
+
+bool ReadOnlyVfsDirectory::IsWritable() const {
+    return false;
+}
+
+bool ReadOnlyVfsDirectory::IsReadable() const {
+    return true;
+}
+
+std::shared_ptr<VfsDirectory> ReadOnlyVfsDirectory::CreateSubdirectory(const std::string& name) {
+    return nullptr;
+}
+
+std::shared_ptr<VfsFile> ReadOnlyVfsDirectory::CreateFile(const std::string& name) {
+    return nullptr;
+}
+
+bool ReadOnlyVfsDirectory::DeleteSubdirectory(const std::string& name) {
+    return false;
+}
+
+bool ReadOnlyVfsDirectory::DeleteFile(const std::string& name) {
+    return false;
+}
+
+bool ReadOnlyVfsDirectory::Rename(const std::string& name) {
+    return false;
+}
+} // namespace FileSys

src/core/file_sys/vfs.h

@@ -0,0 +1,220 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <vector>
+#include "boost/optional.hpp"
+#include "common/common_types.h"
+#include "common/file_util.h"
+
+namespace FileSys {
+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>;
+
+// A class representing a file in an abstract filesystem.
+struct VfsFile : NonCopyable {
+    virtual ~VfsFile();
+
+    // Retrieves the file name.
+    virtual std::string GetName() const = 0;
+    // Retrieves the extension of the file name.
+    virtual std::string GetExtension() const;
+    // Retrieves the size of the file.
+    virtual size_t GetSize() const = 0;
+    // Resizes the file to new_size. Returns whether or not the operation was successful.
+    virtual bool Resize(size_t new_size) = 0;
+    // Gets a pointer to the directory containing this file, returning nullptr if there is none.
+    virtual std::shared_ptr<VfsDirectory> GetContainingDirectory() const = 0;
+
+    // Returns whether or not the file can be written to.
+    virtual bool IsWritable() const = 0;
+    // Returns whether or not the file can be read from.
+    virtual bool IsReadable() const = 0;
+
+    // The primary method of reading from the file. Reads length bytes into data starting at offset
+    // into file. Returns number of bytes successfully read.
+    virtual size_t Read(u8* data, size_t length, size_t offset = 0) const = 0;
+    // The primary method of writing to the file. Writes length bytes from data starting at offset
+    // into file. Returns number of bytes successfully written.
+    virtual size_t Write(const u8* data, size_t length, size_t offset = 0) = 0;
+
+    // Reads exactly one byte at the offset provided, returning boost::none on error.
+    virtual boost::optional<u8> ReadByte(size_t offset = 0) const;
+    // Reads size bytes starting at offset in file into a vector.
+    virtual std::vector<u8> ReadBytes(size_t size, size_t offset = 0) const;
+    // Reads all the bytes from the file into a vector. Equivalent to 'file->Read(file->GetSize(),
+    // 0)'
+    virtual std::vector<u8> ReadAllBytes() const;
+
+    // Reads an array of type T, size number_elements starting at offset.
+    // Returns the number of bytes (sizeof(T)*number_elements) read successfully.
+    template <typename T>
+    size_t ReadArray(T* data, size_t number_elements, size_t offset = 0) const {
+        static_assert(std::is_trivially_copyable<T>::value,
+                      "Data type must be trivially copyable.");
+
+        return Read(reinterpret_cast<u8*>(data), number_elements * sizeof(T), offset);
+    }
+
+    // Reads size bytes into the memory starting at data starting at offset into the file.
+    // Returns the number of bytes read successfully.
+    template <typename T>
+    size_t ReadBytes(T* data, size_t size, size_t offset = 0) const {
+        static_assert(std::is_trivially_copyable<T>::value,
+                      "Data type must be trivially copyable.");
+        return Read(reinterpret_cast<u8*>(data), size, offset);
+    }
+
+    // Reads one object of type T starting at offset in file.
+    // Returns the number of bytes read successfully (sizeof(T)).
+    template <typename T>
+    size_t ReadObject(T* data, size_t offset = 0) const {
+        static_assert(std::is_trivially_copyable<T>::value,
+                      "Data type must be trivially copyable.");
+        return Read(reinterpret_cast<u8*>(data), sizeof(T), offset);
+    }
+
+    // Writes exactly one byte to offset in file and retuns whether or not the byte was written
+    // successfully.
+    virtual bool WriteByte(u8 data, size_t offset = 0);
+    // Writes a vector of bytes to offset in file and returns the number of bytes successfully
+    // written.
+    virtual size_t WriteBytes(std::vector<u8> data, size_t offset = 0);
+
+    // Writes an array of type T, size number_elements to offset in file.
+    // Returns the number of bytes (sizeof(T)*number_elements) written successfully.
+    template <typename T>
+    size_t WriteArray(T* data, size_t number_elements, size_t offset = 0) {
+        static_assert(std::is_trivially_copyable<T>::value,
+                      "Data type must be trivially copyable.");
+
+        return Write(data, number_elements * sizeof(T), offset);
+    }
+
+    // Writes size bytes starting at memory location data to offset in file.
+    // Returns the number of bytes written successfully.
+    template <typename T>
+    size_t WriteBytes(T* data, size_t size, size_t offset = 0) {
+        static_assert(std::is_trivially_copyable<T>::value,
+                      "Data type must be trivially copyable.");
+        return Write(reinterpret_cast<u8*>(data), size, offset);
+    }
+
+    // Writes one object of type T to offset in file.
+    // Returns the number of bytes written successfully (sizeof(T)).
+    template <typename T>
+    size_t WriteObject(const T& data, size_t offset = 0) {
+        static_assert(std::is_trivially_copyable<T>::value,
+                      "Data type must be trivially copyable.");
+        return Write(&data, sizeof(T), offset);
+    }
+
+    // Renames the file to name. Returns whether or not the operation was successsful.
+    virtual bool Rename(const std::string& name) = 0;
+};
+
+// A class representing a directory in an abstract filesystem.
+struct VfsDirectory : NonCopyable {
+    virtual ~VfsDirectory();
+
+    // Retrives the file located at path as if the current directory was root. Returns nullptr if
+    // not found.
+    virtual std::shared_ptr<VfsFile> GetFileRelative(const std::string& path) const;
+    // Calls GetFileRelative(path) on the root of the current directory.
+    virtual std::shared_ptr<VfsFile> GetFileAbsolute(const std::string& path) const;
+
+    // Retrives the directory located at path as if the current directory was root. Returns nullptr
+    // if not found.
+    virtual std::shared_ptr<VfsDirectory> GetDirectoryRelative(const std::string& path) const;
+    // Calls GetDirectoryRelative(path) on the root of the current directory.
+    virtual std::shared_ptr<VfsDirectory> GetDirectoryAbsolute(const std::string& path) const;
+
+    // Returns a vector containing all of the files in this directory.
+    virtual std::vector<std::shared_ptr<VfsFile>> GetFiles() const = 0;
+    // Returns the file with filename matching name. Returns nullptr if directory dosen't have a
+    // file with name.
+    virtual std::shared_ptr<VfsFile> GetFile(const std::string& name) const;
+
+    // Returns a vector containing all of the subdirectories in this directory.
+    virtual std::vector<std::shared_ptr<VfsDirectory>> GetSubdirectories() const = 0;
+    // Returns the directory with name matching name. Returns nullptr if directory dosen't have a
+    // directory with name.
+    virtual std::shared_ptr<VfsDirectory> GetSubdirectory(const std::string& name) const;
+
+    // Returns whether or not the directory can be written to.
+    virtual bool IsWritable() const = 0;
+    // Returns whether of not the directory can be read from.
+    virtual bool IsReadable() const = 0;
+
+    // Returns whether or not the directory is the root of the current file tree.
+    virtual bool IsRoot() const;
+
+    // Returns the name of the directory.
+    virtual std::string GetName() const = 0;
+    // Returns the total size of all files and subdirectories in this directory.
+    virtual size_t GetSize() const;
+    // Returns the parent directory of this directory. Returns nullptr if this directory is root or
+    // has no parent.
+    virtual std::shared_ptr<VfsDirectory> GetParentDirectory() const = 0;
+
+    // Creates a new subdirectory with name name. Returns a pointer to the new directory or nullptr
+    // if the operation failed.
+    virtual std::shared_ptr<VfsDirectory> CreateSubdirectory(const std::string& name) = 0;
+    // Creates a new file with name name. Returns a pointer to the new file or nullptr if the
+    // operation failed.
+    virtual std::shared_ptr<VfsFile> CreateFile(const std::string& name) = 0;
+
+    // Deletes the subdirectory with name and returns true on success.
+    virtual bool DeleteSubdirectory(const std::string& name) = 0;
+    // Deletes all subdirectories and files of subdirectory with name recirsively and then deletes
+    // the subdirectory. Returns true on success.
+    virtual bool DeleteSubdirectoryRecursive(const std::string& name);
+    // Returnes whether or not the file with name name was deleted successfully.
+    virtual bool DeleteFile(const std::string& name) = 0;
+
+    // Returns whether or not this directory was renamed to name.
+    virtual bool Rename(const std::string& name) = 0;
+
+    // Returns whether or not the file with name src was successfully copied to a new file with name
+    // dest.
+    virtual bool Copy(const std::string& src, const std::string& dest);
+
+    // Interprets the file with name file instead as a directory of type directory.
+    // The directory must have a constructor that takes a single argument of type
+    // std::shared_ptr<VfsFile>. Allows to reinterpret container files (i.e NCA, zip, XCI, etc) as a
+    // subdirectory in one call.
+    template <typename Directory>
+    bool InterpretAsDirectory(const std::string& file) {
+        auto file_p = GetFile(file);
+        if (file_p == nullptr)
+            return false;
+        return ReplaceFileWithSubdirectory(file, std::make_shared<Directory>(file_p));
+    }
+
+protected:
+    // Backend for InterpretAsDirectory.
+    // Removes all references to file and adds a reference to dir in the directory's implementation.
+    virtual bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) = 0;
+};
+
+// A convenience partial-implementation of VfsDirectory that stubs out methods that should only work
+// if writable. This is to avoid redundant empty methods everywhere.
+struct ReadOnlyVfsDirectory : public VfsDirectory {
+    bool IsWritable() const override;
+    bool IsReadable() const override;
+    std::shared_ptr<VfsDirectory> CreateSubdirectory(const std::string& name) override;
+    std::shared_ptr<VfsFile> CreateFile(const std::string& name) override;
+    bool DeleteSubdirectory(const std::string& name) override;
+    bool DeleteFile(const std::string& name) override;
+    bool Rename(const std::string& name) override;
+};
+} // namespace FileSys

src/core/file_sys/vfs_offset.cpp

@@ -0,0 +1,92 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "core/file_sys/vfs_offset.h"
+
+namespace FileSys {
+
+OffsetVfsFile::OffsetVfsFile(std::shared_ptr<VfsFile> file_, size_t size_, size_t offset_,
+                             const std::string& name_)
+    : file(file_), offset(offset_), size(size_), name(name_) {}
+
+std::string OffsetVfsFile::GetName() const {
+    return name.empty() ? file->GetName() : name;
+}
+
+size_t OffsetVfsFile::GetSize() const {
+    return size;
+}
+
+bool OffsetVfsFile::Resize(size_t new_size) {
+    if (offset + new_size < file->GetSize()) {
+        size = new_size;
+    } else {
+        auto res = file->Resize(offset + new_size);
+        if (!res)
+            return false;
+        size = new_size;
+    }
+
+    return true;
+}
+
+std::shared_ptr<VfsDirectory> OffsetVfsFile::GetContainingDirectory() const {
+    return file->GetContainingDirectory();
+}
+
+bool OffsetVfsFile::IsWritable() const {
+    return file->IsWritable();
+}
+
+bool OffsetVfsFile::IsReadable() const {
+    return file->IsReadable();
+}
+
+size_t OffsetVfsFile::Read(u8* data, size_t length, size_t r_offset) const {
+    return file->Read(data, TrimToFit(length, r_offset), offset + r_offset);
+}
+
+size_t OffsetVfsFile::Write(const u8* data, size_t length, size_t r_offset) {
+    return file->Write(data, TrimToFit(length, r_offset), offset + r_offset);
+}
+
+boost::optional<u8> OffsetVfsFile::ReadByte(size_t r_offset) const {
+    if (r_offset < size)
+        return file->ReadByte(offset + r_offset);
+
+    return boost::none;
+}
+
+std::vector<u8> OffsetVfsFile::ReadBytes(size_t r_size, size_t r_offset) const {
+    return file->ReadBytes(TrimToFit(r_size, r_offset), offset + r_offset);
+}
+
+std::vector<u8> OffsetVfsFile::ReadAllBytes() const {
+    return file->ReadBytes(size, offset);
+}
+
+bool OffsetVfsFile::WriteByte(u8 data, size_t r_offset) {
+    if (r_offset < size)
+        return file->WriteByte(data, offset + r_offset);
+
+    return false;
+}
+
+size_t OffsetVfsFile::WriteBytes(std::vector<u8> data, size_t r_offset) {
+    return file->Write(data.data(), TrimToFit(data.size(), r_offset), offset + r_offset);
+}
+
+bool OffsetVfsFile::Rename(const std::string& name) {
+    return file->Rename(name);
+}
+
+size_t OffsetVfsFile::GetOffset() const {
+    return offset;
+}
+
+size_t OffsetVfsFile::TrimToFit(size_t r_size, size_t r_offset) const {
+    return std::max<size_t>(std::min<size_t>(size - r_offset, r_size), 0);
+}
+
+} // namespace FileSys

src/core/file_sys/vfs_offset.h

@@ -0,0 +1,46 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+// An implementation of VfsFile that wraps around another VfsFile at a certain offset.
+// Similar to seeking to an offset.
+// If the file is writable, operations that would write past the end of the offset file will expand
+// the size of this wrapper.
+struct OffsetVfsFile : public VfsFile {
+    OffsetVfsFile(std::shared_ptr<VfsFile> file, size_t size, size_t offset = 0,
+                  const std::string& new_name = "");
+
+    std::string GetName() const override;
+    size_t GetSize() const override;
+    bool Resize(size_t new_size) override;
+    std::shared_ptr<VfsDirectory> GetContainingDirectory() const override;
+    bool IsWritable() const override;
+    bool IsReadable() const override;
+    size_t Read(u8* data, size_t length, size_t offset) const override;
+    size_t Write(const u8* data, size_t length, size_t offset) override;
+    boost::optional<u8> ReadByte(size_t offset) const override;
+    std::vector<u8> ReadBytes(size_t size, size_t offset) const override;
+    std::vector<u8> ReadAllBytes() const override;
+    bool WriteByte(u8 data, size_t offset) override;
+    size_t WriteBytes(std::vector<u8> data, size_t offset) override;
+
+    bool Rename(const std::string& name) override;
+
+    size_t GetOffset() const;
+
+private:
+    size_t TrimToFit(size_t r_size, size_t r_offset) const;
+
+    std::shared_ptr<VfsFile> file;
+    size_t offset;
+    size_t size;
+    std::string name;
+};
+
+} // namespace FileSys

src/core/file_sys/vfs_real.cpp

@@ -0,0 +1,168 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "common/common_paths.h"
+#include "common/logging/log.h"
+#include "core/file_sys/vfs_real.h"
+
+namespace FileSys {
+
+static std::string PermissionsToCharArray(Mode perms) {
+    std::string out;
+    switch (perms) {
+    case Mode::Read:
+        out += "r";
+        break;
+    case Mode::Write:
+        out += "r+";
+        break;
+    case Mode::Append:
+        out += "a";
+        break;
+    }
+    return out + "b";
+}
+
+RealVfsFile::RealVfsFile(const std::string& path_, Mode perms_)
+    : backing(path_, PermissionsToCharArray(perms_).c_str()), path(path_),
+      parent_path(FileUtil::GetParentPath(path_)),
+      path_components(FileUtil::SplitPathComponents(path_)),
+      parent_components(FileUtil::SliceVector(path_components, 0, path_components.size() - 1)),
+      perms(perms_) {}
+
+std::string RealVfsFile::GetName() const {
+    return path_components.back();
+}
+
+size_t RealVfsFile::GetSize() const {
+    return backing.GetSize();
+}
+
+bool RealVfsFile::Resize(size_t new_size) {
+    return backing.Resize(new_size);
+}
+
+std::shared_ptr<VfsDirectory> RealVfsFile::GetContainingDirectory() const {
+    return std::make_shared<RealVfsDirectory>(parent_path, perms);
+}
+
+bool RealVfsFile::IsWritable() const {
+    return perms == Mode::Append || perms == Mode::Write;
+}
+
+bool RealVfsFile::IsReadable() const {
+    return perms == Mode::Read || perms == Mode::Write;
+}
+
+size_t RealVfsFile::Read(u8* data, size_t length, size_t offset) const {
+    if (!backing.Seek(offset, SEEK_SET))
+        return 0;
+    return backing.ReadBytes(data, length);
+}
+
+size_t RealVfsFile::Write(const u8* data, size_t length, size_t offset) {
+    if (!backing.Seek(offset, SEEK_SET))
+        return 0;
+    return backing.WriteBytes(data, length);
+}
+
+bool RealVfsFile::Rename(const std::string& name) {
+    const auto out = FileUtil::Rename(GetName(), name);
+    path = parent_path + DIR_SEP + name;
+    path_components = parent_components;
+    path_components.push_back(name);
+    backing = FileUtil::IOFile(path, PermissionsToCharArray(perms).c_str());
+    return out;
+}
+
+RealVfsDirectory::RealVfsDirectory(const std::string& path_, Mode perms_)
+    : 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::Write || perms == Mode::Append))
+        FileUtil::CreateDir(path);
+    unsigned size;
+    if (perms != Mode::Append) {
+        FileUtil::ForeachDirectoryEntry(
+            &size, path,
+            [this](unsigned* 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::vector<std::shared_ptr<VfsFile>> RealVfsDirectory::GetFiles() const {
+    return std::vector<std::shared_ptr<VfsFile>>(files);
+}
+
+std::vector<std::shared_ptr<VfsDirectory>> RealVfsDirectory::GetSubdirectories() const {
+    return std::vector<std::shared_ptr<VfsDirectory>>(subdirectories);
+}
+
+bool RealVfsDirectory::IsWritable() const {
+    return perms == Mode::Write || perms == Mode::Append;
+}
+
+bool RealVfsDirectory::IsReadable() const {
+    return perms == Mode::Read || perms == Mode::Write;
+}
+
+std::string RealVfsDirectory::GetName() const {
+    return path_components.back();
+}
+
+std::shared_ptr<VfsDirectory> RealVfsDirectory::GetParentDirectory() const {
+    if (path_components.size() <= 1)
+        return nullptr;
+
+    return std::make_shared<RealVfsDirectory>(parent_path, perms);
+}
+
+std::shared_ptr<VfsDirectory> RealVfsDirectory::CreateSubdirectory(const std::string& name) {
+    if (!FileUtil::CreateDir(path + DIR_SEP + name))
+        return nullptr;
+    subdirectories.emplace_back(std::make_shared<RealVfsDirectory>(path + DIR_SEP + name, perms));
+    return subdirectories.back();
+}
+
+std::shared_ptr<VfsFile> RealVfsDirectory::CreateFile(const std::string& name) {
+    if (!FileUtil::CreateEmptyFile(path + DIR_SEP + name))
+        return nullptr;
+    files.emplace_back(std::make_shared<RealVfsFile>(path + DIR_SEP + name, perms));
+    return files.back();
+}
+
+bool RealVfsDirectory::DeleteSubdirectory(const std::string& name) {
+    return FileUtil::DeleteDirRecursively(path + DIR_SEP + name);
+}
+
+bool RealVfsDirectory::DeleteFile(const std::string& name) {
+    return FileUtil::Delete(path + DIR_SEP + name);
+}
+
+bool RealVfsDirectory::Rename(const std::string& name) {
+    return FileUtil::Rename(path, parent_path + DIR_SEP + name);
+}
+
+bool RealVfsDirectory::ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) {
+    auto iter = std::find(files.begin(), files.end(), file);
+    if (iter == files.end())
+        return false;
+
+    files[iter - files.begin()] = files.back();
+    files.pop_back();
+
+    subdirectories.emplace_back(dir);
+
+    return true;
+}
+} // namespace FileSys

src/core/file_sys/vfs_real.h

@@ -0,0 +1,65 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/file_util.h"
+#include "core/file_sys/filesystem.h"
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+// An implmentation of VfsFile that represents a file on the user's computer.
+struct RealVfsFile : public VfsFile {
+    RealVfsFile(const std::string& name, Mode perms = Mode::Read);
+
+    std::string GetName() const override;
+    size_t GetSize() const override;
+    bool Resize(size_t new_size) override;
+    std::shared_ptr<VfsDirectory> GetContainingDirectory() const override;
+    bool IsWritable() const override;
+    bool IsReadable() const override;
+    size_t Read(u8* data, size_t length, size_t offset) const override;
+    size_t Write(const u8* data, size_t length, size_t offset) override;
+    bool Rename(const std::string& name) override;
+
+private:
+    FileUtil::IOFile backing;
+    std::string path;
+    std::string parent_path;
+    std::vector<std::string> path_components;
+    std::vector<std::string> parent_components;
+    Mode perms;
+};
+
+// An implementation of VfsDirectory that represents a directory on the user's computer.
+struct RealVfsDirectory : public VfsDirectory {
+    RealVfsDirectory(const std::string& path, Mode perms);
+
+    std::vector<std::shared_ptr<VfsFile>> GetFiles() const override;
+    std::vector<std::shared_ptr<VfsDirectory>> GetSubdirectories() const override;
+    bool IsWritable() const override;
+    bool IsReadable() const override;
+    std::string GetName() const override;
+    std::shared_ptr<VfsDirectory> GetParentDirectory() const override;
+    std::shared_ptr<VfsDirectory> CreateSubdirectory(const std::string& name) override;
+    std::shared_ptr<VfsFile> CreateFile(const std::string& name) override;
+    bool DeleteSubdirectory(const std::string& name) override;
+    bool DeleteFile(const std::string& name) override;
+    bool Rename(const std::string& name) override;
+
+protected:
+    bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
+
+private:
+    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

src/core/hle/service/am/am.cpp

@@ -621,7 +621,7 @@ void IApplicationFunctions::EnsureSaveData(Kernel::HLERequestContext& ctx) {
     IPC::ResponseBuilder rb{ctx, 4};
 
     FileSys::Path unused;
-    auto savedata = FileSystem::OpenFileSystem(FileSystem::Type::SaveData, unused);
+    auto savedata = FileSystem::OpenFileSystem(FileSystem::Type::SaveData);
     if (savedata.Failed()) {
         // Create the save data and return an error indicating that the operation was performed.
         FileSystem::FormatFileSystem(FileSystem::Type::SaveData);

src/core/hle/service/filesystem/filesystem.cpp

@@ -2,36 +2,221 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
-#include <boost/container/flat_map.hpp>
+#include "boost/container/flat_map.hpp"
+#include "common/assert.h"
+#include "common/common_paths.h"
 #include "common/file_util.h"
+#include "core/core.h"
+#include "core/file_sys/errors.h"
 #include "core/file_sys/filesystem.h"
-#include "core/file_sys/savedata_factory.h"
-#include "core/file_sys/sdmc_factory.h"
+#include "core/file_sys/vfs.h"
+#include "core/file_sys/vfs_offset.h"
+#include "core/file_sys/vfs_real.h"
+#include "core/hle/kernel/process.h"
 #include "core/hle/service/filesystem/filesystem.h"
 #include "core/hle/service/filesystem/fsp_srv.h"
 
 namespace Service::FileSystem {
 
+// Size of emulated sd card free space, reported in bytes.
+// Just using 32GB because thats reasonable
+// TODO(DarkLordZach): Eventually make this configurable in settings.
+constexpr u64 EMULATED_SD_REPORTED_SIZE = 32000000000;
+
+static FileSys::VirtualDir GetDirectoryRelativeWrapped(FileSys::VirtualDir base,
+                                                       const std::string& dir_name) {
+    if (dir_name == "." || dir_name == "" || dir_name == "/" || dir_name == "\\")
+        return base;
+
+    return base->GetDirectoryRelative(dir_name);
+}
+
+VfsDirectoryServiceWrapper::VfsDirectoryServiceWrapper(FileSys::VirtualDir backing_)
+    : backing(backing_) {}
+
+std::string VfsDirectoryServiceWrapper::GetName() const {
+    return backing->GetName();
+}
+
+ResultCode VfsDirectoryServiceWrapper::CreateFile(const std::string& path, u64 size) const {
+    auto dir = GetDirectoryRelativeWrapped(backing, FileUtil::GetParentPath(path));
+    auto file = dir->CreateFile(FileUtil::GetFilename(path));
+    if (file == nullptr)
+        return ResultCode(-1);
+    if (!file->Resize(size))
+        return ResultCode(-1);
+    return RESULT_SUCCESS;
+}
+
+ResultCode VfsDirectoryServiceWrapper::DeleteFile(const std::string& path) const {
+    auto dir = GetDirectoryRelativeWrapped(backing, FileUtil::GetParentPath(path));
+    if (!backing->DeleteFile(FileUtil::GetFilename(path)))
+        return ResultCode(-1);
+    return RESULT_SUCCESS;
+}
+
+ResultCode VfsDirectoryServiceWrapper::CreateDirectory(const std::string& path) const {
+    auto dir = GetDirectoryRelativeWrapped(backing, FileUtil::GetParentPath(path));
+    if (dir == nullptr && FileUtil::GetFilename(FileUtil::GetParentPath(path)).empty())
+        dir = backing;
+    auto new_dir = dir->CreateSubdirectory(FileUtil::GetFilename(path));
+    if (new_dir == nullptr)
+        return ResultCode(-1);
+    return RESULT_SUCCESS;
+}
+
+ResultCode VfsDirectoryServiceWrapper::DeleteDirectory(const std::string& path) const {
+    auto dir = GetDirectoryRelativeWrapped(backing, FileUtil::GetParentPath(path));
+    if (!dir->DeleteSubdirectory(FileUtil::GetFilename(path)))
+        return ResultCode(-1);
+    return RESULT_SUCCESS;
+}
+
+ResultCode VfsDirectoryServiceWrapper::DeleteDirectoryRecursively(const std::string& path) const {
+    auto dir = GetDirectoryRelativeWrapped(backing, FileUtil::GetParentPath(path));
+    if (!dir->DeleteSubdirectoryRecursive(FileUtil::GetFilename(path)))
+        return ResultCode(-1);
+    return RESULT_SUCCESS;
+}
+
+ResultCode VfsDirectoryServiceWrapper::RenameFile(const std::string& src_path,
+                                                  const std::string& dest_path) const {
+    auto src = backing->GetFileRelative(src_path);
+    if (FileUtil::GetParentPath(src_path) == FileUtil::GetParentPath(dest_path)) {
+        // Use more-optimized vfs implementation rename.
+        if (src == nullptr)
+            return FileSys::ERROR_PATH_NOT_FOUND;
+        if (!src->Rename(FileUtil::GetFilename(dest_path)))
+            return ResultCode(-1);
+        return RESULT_SUCCESS;
+    }
+
+    // Move by hand -- TODO(DarkLordZach): Optimize
+    auto c_res = CreateFile(dest_path, src->GetSize());
+    if (c_res != RESULT_SUCCESS)
+        return c_res;
+
+    auto dest = backing->GetFileRelative(dest_path);
+    ASSERT_MSG(dest != nullptr, "Newly created file with success cannot be found.");
+
+    ASSERT_MSG(dest->WriteBytes(src->ReadAllBytes()) == src->GetSize(),
+               "Could not write all of the bytes but everything else has succeded.");
+
+    if (!src->GetContainingDirectory()->DeleteFile(FileUtil::GetFilename(src_path)))
+        return ResultCode(-1);
+
+    return RESULT_SUCCESS;
+}
+
+ResultCode VfsDirectoryServiceWrapper::RenameDirectory(const std::string& src_path,
+                                                       const std::string& dest_path) const {
+    auto src = GetDirectoryRelativeWrapped(backing, src_path);
+    if (FileUtil::GetParentPath(src_path) == FileUtil::GetParentPath(dest_path)) {
+        // Use more-optimized vfs implementation rename.
+        if (src == nullptr)
+            return FileSys::ERROR_PATH_NOT_FOUND;
+        if (!src->Rename(FileUtil::GetFilename(dest_path)))
+            return ResultCode(-1);
+        return RESULT_SUCCESS;
+    }
+
+    // TODO(DarkLordZach): Implement renaming across the tree (move).
+    ASSERT_MSG(false,
+               "Could not rename directory with path \"{}\" to new path \"{}\" because parent dirs "
+               "don't match -- UNIMPLEMENTED",
+               src_path, dest_path);
+
+    return ResultCode(-1);
+}
+
+ResultVal<FileSys::VirtualFile> VfsDirectoryServiceWrapper::OpenFile(const std::string& path,
+                                                                     FileSys::Mode mode) const {
+    auto file = backing->GetFileRelative(path);
+    if (file == nullptr)
+        return FileSys::ERROR_PATH_NOT_FOUND;
+
+    if ((static_cast<u32>(mode) & static_cast<u32>(FileSys::Mode::Append)) != 0) {
+        return MakeResult<FileSys::VirtualFile>(
+            std::make_shared<FileSys::OffsetVfsFile>(file, 0, file->GetSize()));
+    }
+
+    return MakeResult<FileSys::VirtualFile>(file);
+}
+
+ResultVal<FileSys::VirtualDir> VfsDirectoryServiceWrapper::OpenDirectory(const std::string& path) {
+    auto dir = GetDirectoryRelativeWrapped(backing, path);
+    if (dir == nullptr)
+        return ResultCode(-1);
+    return MakeResult(dir);
+}
+
+u64 VfsDirectoryServiceWrapper::GetFreeSpaceSize() const {
+    if (backing->IsWritable())
+        return EMULATED_SD_REPORTED_SIZE;
+
+    return 0;
+}
+
+ResultVal<FileSys::EntryType> VfsDirectoryServiceWrapper::GetEntryType(
+    const std::string& path) const {
+    auto dir = GetDirectoryRelativeWrapped(backing, FileUtil::GetParentPath(path));
+    if (dir == nullptr)
+        return ResultCode(-1);
+    auto filename = FileUtil::GetFilename(path);
+    if (dir->GetFile(filename) != nullptr)
+        return MakeResult(FileSys::EntryType::File);
+    if (dir->GetSubdirectory(filename) != nullptr)
+        return MakeResult(FileSys::EntryType::Directory);
+    return ResultCode(-1);
+}
+
+// A deferred filesystem for nand save data.
+// This must be deferred because the directory is dependent on title id, which is not set at
+// registration time.
+struct SaveDataDeferredFilesystem : DeferredFilesystem {
+protected:
+    FileSys::VirtualDir CreateFilesystem() override {
+        u64 title_id = Core::CurrentProcess()->program_id;
+        // TODO(DarkLordZach): Users
+        u32 user_id = 0;
+        std::string nand_directory = fmt::format(
+            "{}save/{:016X}/{:08X}/", FileUtil::GetUserPath(D_NAND_IDX), title_id, user_id);
+
+        auto savedata =
+            std::make_shared<FileSys::RealVfsDirectory>(nand_directory, FileSys::Mode::Write);
+        return savedata;
+    }
+};
+
 /**
  * Map of registered file systems, identified by type. Once an file system is registered here, it
  * is never removed until UnregisterFileSystems is called.
  */
-static boost::container::flat_map<Type, std::unique_ptr<FileSys::FileSystemFactory>> filesystem_map;
+static boost::container::flat_map<Type, std::unique_ptr<DeferredFilesystem>> filesystem_map;
+static FileSys::VirtualFile filesystem_romfs = nullptr;
 
-ResultCode RegisterFileSystem(std::unique_ptr<FileSys::FileSystemFactory>&& factory, Type type) {
+ResultCode RegisterFileSystem(std::unique_ptr<DeferredFilesystem>&& factory, Type type) {
     auto result = filesystem_map.emplace(type, std::move(factory));
 
     bool inserted = result.second;
     ASSERT_MSG(inserted, "Tried to register more than one system with same id code");
 
     auto& filesystem = result.first->second;
+    LOG_DEBUG(Service_FS, "Registered file system with id code 0x{:08X}", static_cast<u32>(type));
+    return RESULT_SUCCESS;
+}
+
+ResultCode RegisterRomFS(FileSys::VirtualFile filesystem) {
+    ASSERT_MSG(filesystem_romfs == nullptr,
+               "Tried to register more than one system with same id code");
+
+    filesystem_romfs = filesystem;
     LOG_DEBUG(Service_FS, "Registered file system {} with id code 0x{:08X}", filesystem->GetName(),
-              static_cast<u32>(type));
+              static_cast<u32>(Type::RomFS));
     return RESULT_SUCCESS;
 }
 
-ResultVal<std::unique_ptr<FileSys::FileSystemBackend>> OpenFileSystem(Type type,
-                                                                      FileSys::Path& path) {
+ResultVal<FileSys::VirtualDir> OpenFileSystem(Type type) {
     LOG_TRACE(Service_FS, "Opening FileSystem with type={}", static_cast<u32>(type));
 
     auto itr = filesystem_map.find(type);
@@ -40,7 +225,13 @@ ResultVal<std::unique_ptr<FileSys::FileSystemBackend>> OpenFileSystem(Type type,
         return ResultCode(-1);
     }
 
-    return itr->second->Open(path);
+    return MakeResult(itr->second->Get());
+}
+
+ResultVal<FileSys::VirtualFile> OpenRomFS() {
+    if (filesystem_romfs == nullptr)
+        return ResultCode(-1);
+    return MakeResult(filesystem_romfs);
 }
 
 ResultCode FormatFileSystem(Type type) {
@@ -52,21 +243,21 @@ ResultCode FormatFileSystem(Type type) {
         return ResultCode(-1);
     }
 
-    FileSys::Path unused;
-    return itr->second->Format(unused);
+    return itr->second->Get()->GetParentDirectory()->DeleteSubdirectory(
+               itr->second->Get()->GetName())
+               ? RESULT_SUCCESS
+               : ResultCode(-1);
 }
 
 void RegisterFileSystems() {
     filesystem_map.clear();
+    filesystem_romfs = nullptr;
 
-    std::string nand_directory = FileUtil::GetUserPath(D_NAND_IDX);
     std::string sd_directory = FileUtil::GetUserPath(D_SDMC_IDX);
+    auto sdcard = std::make_shared<FileSys::RealVfsDirectory>(sd_directory, FileSys::Mode::Write);
+    RegisterFileSystem(std::make_unique<DeferredFilesystem>(sdcard), Type::SDMC);
 
-    auto savedata = std::make_unique<FileSys::SaveData_Factory>(std::move(nand_directory));
-    RegisterFileSystem(std::move(savedata), Type::SaveData);
-
-    auto sdcard = std::make_unique<FileSys::SDMC_Factory>(std::move(sd_directory));
-    RegisterFileSystem(std::move(sdcard), Type::SDMC);
+    RegisterFileSystem(std::make_unique<SaveDataDeferredFilesystem>(), Type::SaveData);
 }
 
 void InstallInterfaces(SM::ServiceManager& service_manager) {

src/core/hle/service/filesystem/filesystem.h

@@ -6,6 +6,8 @@
 
 #include <memory>
 #include "common/common_types.h"
+#include "core/file_sys/filesystem.h"
+#include "core/file_sys/vfs.h"
 #include "core/hle/result.h"
 
 namespace FileSys {
@@ -29,12 +31,136 @@ enum class Type {
     SDMC = 3,
 };
 
+// A class that wraps a VfsDirectory with methods that return ResultVal and ResultCode instead of
+// pointers and booleans. This makes using a VfsDirectory with switch services much easier and
+// avoids repetitive code.
+class VfsDirectoryServiceWrapper {
+public:
+    explicit VfsDirectoryServiceWrapper(FileSys::VirtualDir backing);
+
+    /**
+     * Get a descriptive name for the archive (e.g. "RomFS", "SaveData", etc.)
+     */
+    std::string GetName() const;
+
+    /**
+     * Create a file specified by its path
+     * @param path Path relative to the Archive
+     * @param size The size of the new file, filled with zeroes
+     * @return Result of the operation
+     */
+    ResultCode CreateFile(const std::string& path, u64 size) const;
+
+    /**
+     * Delete a file specified by its path
+     * @param path Path relative to the archive
+     * @return Result of the operation
+     */
+    ResultCode DeleteFile(const std::string& path) const;
+
+    /**
+     * Create a directory specified by its path
+     * @param path Path relative to the archive
+     * @return Result of the operation
+     */
+    ResultCode CreateDirectory(const std::string& path) const;
+
+    /**
+     * Delete a directory specified by its path
+     * @param path Path relative to the archive
+     * @return Result of the operation
+     */
+    ResultCode DeleteDirectory(const std::string& path) const;
+
+    /**
+     * Delete a directory specified by its path and anything under it
+     * @param path Path relative to the archive
+     * @return Result of the operation
+     */
+    ResultCode DeleteDirectoryRecursively(const std::string& path) const;
+
+    /**
+     * Rename a File specified by its path
+     * @param src_path Source path relative to the archive
+     * @param dest_path Destination path relative to the archive
+     * @return Result of the operation
+     */
+    ResultCode RenameFile(const std::string& src_path, const std::string& dest_path) const;
+
+    /**
+     * Rename a Directory specified by its path
+     * @param src_path Source path relative to the archive
+     * @param dest_path Destination path relative to the archive
+     * @return Result of the operation
+     */
+    ResultCode RenameDirectory(const std::string& src_path, const std::string& dest_path) const;
+
+    /**
+     * Open a file specified by its path, using the specified mode
+     * @param path Path relative to the archive
+     * @param mode Mode to open the file with
+     * @return Opened file, or error code
+     */
+    ResultVal<FileSys::VirtualFile> OpenFile(const std::string& path, FileSys::Mode mode) const;
+
+    /**
+     * Open a directory specified by its path
+     * @param path Path relative to the archive
+     * @return Opened directory, or error code
+     */
+    ResultVal<FileSys::VirtualDir> OpenDirectory(const std::string& path);
+
+    /**
+     * Get the free space
+     * @return The number of free bytes in the archive
+     */
+    u64 GetFreeSpaceSize() const;
+
+    /**
+     * Get the type of the specified path
+     * @return The type of the specified path or error code
+     */
+    ResultVal<FileSys::EntryType> GetEntryType(const std::string& path) const;
+
+private:
+    FileSys::VirtualDir backing;
+};
+
+// A class that deferres the creation of a filesystem until a later time.
+// This is useful if construction depends on a variable not known when the filesystem is registered.
+// Construct this with a filesystem (VirtualDir) to avoid the deferrence feature or override the
+//     CreateFilesystem method which will be called on first use.
+struct DeferredFilesystem {
+    DeferredFilesystem() = default;
+
+    explicit DeferredFilesystem(FileSys::VirtualDir vfs_directory) : fs(std::move(vfs_directory)) {}
+
+    FileSys::VirtualDir Get() {
+        if (fs == nullptr)
+            fs = CreateFilesystem();
+
+        return fs;
+    }
+
+    virtual ~DeferredFilesystem() = default;
+
+protected:
+    virtual FileSys::VirtualDir CreateFilesystem() {
+        return fs;
+    }
+
+private:
+    FileSys::VirtualDir fs;
+};
+
 /**
  * Registers a FileSystem, instances of which can later be opened using its IdCode.
  * @param factory FileSystem backend interface to use
  * @param type Type used to access this type of FileSystem
  */
-ResultCode RegisterFileSystem(std::unique_ptr<FileSys::FileSystemFactory>&& factory, Type type);
+ResultCode RegisterFileSystem(std::unique_ptr<DeferredFilesystem>&& fs, Type type);
+
+ResultCode RegisterRomFS(FileSys::VirtualFile fs);
 
 /**
  * Opens a file system
@@ -42,8 +168,9 @@ ResultCode RegisterFileSystem(std::unique_ptr<FileSys::FileSystemFactory>&& fact
  * @param path Path to the file system, used with Binary paths
  * @return FileSys::FileSystemBackend interface to the file system
  */
-ResultVal<std::unique_ptr<FileSys::FileSystemBackend>> OpenFileSystem(Type type,
-                                                                      FileSys::Path& path);
+ResultVal<FileSys::VirtualDir> OpenFileSystem(Type type);
+
+ResultVal<FileSys::VirtualFile> OpenRomFS();
 
 /**
  * Formats a file system

src/core/hle/service/filesystem/fsp_srv.cpp

@@ -19,8 +19,8 @@ namespace Service::FileSystem {
 
 class IStorage final : public ServiceFramework<IStorage> {
 public:
-    IStorage(std::unique_ptr<FileSys::StorageBackend>&& backend)
-        : ServiceFramework("IStorage"), backend(std::move(backend)) {
+    IStorage(FileSys::VirtualFile backend_)
+        : ServiceFramework("IStorage"), backend(std::move(backend_)) {
         static const FunctionInfo functions[] = {
             {0, &IStorage::Read, "Read"}, {1, nullptr, "Write"},   {2, nullptr, "Flush"},
             {3, nullptr, "SetSize"},      {4, nullptr, "GetSize"}, {5, nullptr, "OperateRange"},
@@ -29,7 +29,7 @@ public:
     }
 
 private:
-    std::unique_ptr<FileSys::StorageBackend> backend;
+    FileSys::VirtualFile backend;
 
     void Read(Kernel::HLERequestContext& ctx) {
         IPC::RequestParser rp{ctx};
@@ -51,8 +51,8 @@ private:
         }
 
         // Read the data from the Storage backend
-        std::vector<u8> output(length);
-        ResultVal<size_t> res = backend->Read(offset, length, output.data());
+        std::vector<u8> output = backend->ReadBytes(length, offset);
+        auto res = MakeResult<size_t>(output.size());
         if (res.Failed()) {
             IPC::ResponseBuilder rb{ctx, 2};
             rb.Push(res.Code());
@@ -69,8 +69,8 @@ private:
 
 class IFile final : public ServiceFramework<IFile> {
 public:
-    explicit IFile(std::unique_ptr<FileSys::StorageBackend>&& backend)
-        : ServiceFramework("IFile"), backend(std::move(backend)) {
+    explicit IFile(FileSys::VirtualFile backend_)
+        : ServiceFramework("IFile"), backend(std::move(backend_)) {
         static const FunctionInfo functions[] = {
             {0, &IFile::Read, "Read"},       {1, &IFile::Write, "Write"},
             {2, &IFile::Flush, "Flush"},     {3, &IFile::SetSize, "SetSize"},
@@ -80,7 +80,7 @@ public:
     }
 
 private:
-    std::unique_ptr<FileSys::StorageBackend> backend;
+    FileSys::VirtualFile backend;
 
     void Read(Kernel::HLERequestContext& ctx) {
         IPC::RequestParser rp{ctx};
@@ -103,8 +103,8 @@ private:
         }
 
         // Read the data from the Storage backend
-        std::vector<u8> output(length);
-        ResultVal<size_t> res = backend->Read(offset, length, output.data());
+        std::vector<u8> output = backend->ReadBytes(length, offset);
+        auto res = MakeResult<size_t>(output.size());
         if (res.Failed()) {
             IPC::ResponseBuilder rb{ctx, 2};
             rb.Push(res.Code());
@@ -139,9 +139,10 @@ private:
             return;
         }
 
-        // Write the data to the Storage backend
         std::vector<u8> data = ctx.ReadBuffer();
-        ResultVal<size_t> res = backend->Write(offset, length, true, data.data());
+        data.resize(length);
+        // Write the data to the Storage backend
+        auto res = MakeResult<size_t>(backend->WriteBytes(data, offset));
         if (res.Failed()) {
             IPC::ResponseBuilder rb{ctx, 2};
             rb.Push(res.Code());
@@ -154,7 +155,8 @@ private:
 
     void Flush(Kernel::HLERequestContext& ctx) {
         LOG_DEBUG(Service_FS, "called");
-        backend->Flush();
+
+        // Exists for SDK compatibiltity -- No need to flush file.
 
         IPC::ResponseBuilder rb{ctx, 2};
         rb.Push(RESULT_SUCCESS);
@@ -163,7 +165,7 @@ private:
     void SetSize(Kernel::HLERequestContext& ctx) {
         IPC::RequestParser rp{ctx};
         const u64 size = rp.Pop<u64>();
-        backend->SetSize(size);
+        backend->Resize(size);
         LOG_DEBUG(Service_FS, "called, size={}", size);
 
         IPC::ResponseBuilder rb{ctx, 2};
@@ -180,19 +182,38 @@ private:
     }
 };
 
+template <typename T>
+static void BuildEntryIndex(std::vector<FileSys::Entry>& entries, const std::vector<T>& new_data,
+                            FileSys::EntryType type) {
+    for (const auto& new_entry : new_data) {
+        FileSys::Entry entry;
+        entry.filename[0] = '\0';
+        std::strncat(entry.filename, new_entry->GetName().c_str(), FileSys::FILENAME_LENGTH - 1);
+        entry.type = type;
+        entry.file_size = new_entry->GetSize();
+        entries.emplace_back(std::move(entry));
+    }
+}
+
 class IDirectory final : public ServiceFramework<IDirectory> {
 public:
-    explicit IDirectory(std::unique_ptr<FileSys::DirectoryBackend>&& backend)
-        : ServiceFramework("IDirectory"), backend(std::move(backend)) {
+    explicit IDirectory(FileSys::VirtualDir backend_)
+        : ServiceFramework("IDirectory"), backend(std::move(backend_)) {
         static const FunctionInfo functions[] = {
             {0, &IDirectory::Read, "Read"},
             {1, &IDirectory::GetEntryCount, "GetEntryCount"},
         };
         RegisterHandlers(functions);
+
+        // Build entry index now to save time later.
+        BuildEntryIndex(entries, backend->GetFiles(), FileSys::File);
+        BuildEntryIndex(entries, backend->GetSubdirectories(), FileSys::Directory);
     }
 
 private:
-    std::unique_ptr<FileSys::DirectoryBackend> backend;
+    FileSys::VirtualDir backend;
+    std::vector<FileSys::Entry> entries;
+    u64 next_entry_index = 0;
 
     void Read(Kernel::HLERequestContext& ctx) {
         IPC::RequestParser rp{ctx};
@@ -203,26 +224,31 @@ private:
         // Calculate how many entries we can fit in the output buffer
         u64 count_entries = ctx.GetWriteBufferSize() / sizeof(FileSys::Entry);
 
+        // Cap at total number of entries.
+        u64 actual_entries = std::min(count_entries, entries.size() - next_entry_index);
+
         // Read the data from the Directory backend
-        std::vector<FileSys::Entry> entries(count_entries);
-        u64 read_entries = backend->Read(count_entries, entries.data());
+        std::vector<FileSys::Entry> entry_data(entries.begin() + next_entry_index,
+                                               entries.begin() + next_entry_index + actual_entries);
+
+        next_entry_index += actual_entries;
 
         // Convert the data into a byte array
-        std::vector<u8> output(entries.size() * sizeof(FileSys::Entry));
-        std::memcpy(output.data(), entries.data(), output.size());
+        std::vector<u8> output(entry_data.size() * sizeof(FileSys::Entry));
+        std::memcpy(output.data(), entry_data.data(), output.size());
 
         // Write the data to memory
         ctx.WriteBuffer(output);
 
         IPC::ResponseBuilder rb{ctx, 4};
         rb.Push(RESULT_SUCCESS);
-        rb.Push(read_entries);
+        rb.Push(actual_entries);
     }
 
     void GetEntryCount(Kernel::HLERequestContext& ctx) {
         LOG_DEBUG(Service_FS, "called");
 
-        u64 count = backend->GetEntryCount();
+        u64 count = entries.size() - next_entry_index;
 
         IPC::ResponseBuilder rb{ctx, 4};
         rb.Push(RESULT_SUCCESS);
@@ -232,7 +258,7 @@ private:
 
 class IFileSystem final : public ServiceFramework<IFileSystem> {
 public:
-    explicit IFileSystem(std::unique_ptr<FileSys::FileSystemBackend>&& backend)
+    explicit IFileSystem(FileSys::VirtualDir backend)
         : ServiceFramework("IFileSystem"), backend(std::move(backend)) {
         static const FunctionInfo functions[] = {
             {0, &IFileSystem::CreateFile, "CreateFile"},
@@ -267,7 +293,7 @@ public:
         LOG_DEBUG(Service_FS, "called file {} mode 0x{:X} size 0x{:08X}", name, mode, size);
 
         IPC::ResponseBuilder rb{ctx, 2};
-        rb.Push(backend->CreateFile(name, size));
+        rb.Push(backend.CreateFile(name, size));
     }
 
     void DeleteFile(Kernel::HLERequestContext& ctx) {
@@ -279,7 +305,7 @@ public:
         LOG_DEBUG(Service_FS, "called file {}", name);
 
         IPC::ResponseBuilder rb{ctx, 2};
-        rb.Push(backend->DeleteFile(name));
+        rb.Push(backend.DeleteFile(name));
     }
 
     void CreateDirectory(Kernel::HLERequestContext& ctx) {
@@ -291,7 +317,7 @@ public:
         LOG_DEBUG(Service_FS, "called directory {}", name);
 
         IPC::ResponseBuilder rb{ctx, 2};
-        rb.Push(backend->CreateDirectory(name));
+        rb.Push(backend.CreateDirectory(name));
     }
 
     void RenameFile(Kernel::HLERequestContext& ctx) {
@@ -309,7 +335,7 @@ public:
         LOG_DEBUG(Service_FS, "called file '{}' to file '{}'", src_name, dst_name);
 
         IPC::ResponseBuilder rb{ctx, 2};
-        rb.Push(backend->RenameFile(src_name, dst_name));
+        rb.Push(backend.RenameFile(src_name, dst_name));
     }
 
     void OpenFile(Kernel::HLERequestContext& ctx) {
@@ -322,14 +348,14 @@ public:
 
         LOG_DEBUG(Service_FS, "called file {} mode {}", name, static_cast<u32>(mode));
 
-        auto result = backend->OpenFile(name, mode);
+        auto result = backend.OpenFile(name, mode);
         if (result.Failed()) {
             IPC::ResponseBuilder rb{ctx, 2};
             rb.Push(result.Code());
             return;
         }
 
-        auto file = std::move(result.Unwrap());
+        IFile file(result.Unwrap());
 
         IPC::ResponseBuilder rb{ctx, 2, 0, 1};
         rb.Push(RESULT_SUCCESS);
@@ -347,14 +373,14 @@ public:
 
         LOG_DEBUG(Service_FS, "called directory {} filter {}", name, filter_flags);
 
-        auto result = backend->OpenDirectory(name);
+        auto result = backend.OpenDirectory(name);
         if (result.Failed()) {
             IPC::ResponseBuilder rb{ctx, 2};
             rb.Push(result.Code());
             return;
         }
 
-        auto directory = std::move(result.Unwrap());
+        IDirectory directory(result.Unwrap());
 
         IPC::ResponseBuilder rb{ctx, 2, 0, 1};
         rb.Push(RESULT_SUCCESS);
@@ -369,7 +395,7 @@ public:
 
         LOG_DEBUG(Service_FS, "called file {}", name);
 
-        auto result = backend->GetEntryType(name);
+        auto result = backend.GetEntryType(name);
         if (result.Failed()) {
             IPC::ResponseBuilder rb{ctx, 2};
             rb.Push(result.Code());
@@ -389,7 +415,7 @@ public:
     }
 
 private:
-    std::unique_ptr<FileSys::FileSystemBackend> backend;
+    VfsDirectoryServiceWrapper backend;
 };
 
 FSP_SRV::FSP_SRV() : ServiceFramework("fsp-srv") {
@@ -490,8 +516,7 @@ void FSP_SRV::TryLoadRomFS() {
     if (romfs) {
         return;
     }
-    FileSys::Path unused;
-    auto res = OpenFileSystem(Type::RomFS, unused);
+    auto res = OpenRomFS();
     if (res.Succeeded()) {
         romfs = std::move(res.Unwrap());
     }
@@ -507,8 +532,7 @@ void FSP_SRV::Initialize(Kernel::HLERequestContext& ctx) {
 void FSP_SRV::MountSdCard(Kernel::HLERequestContext& ctx) {
     LOG_DEBUG(Service_FS, "called");
 
-    FileSys::Path unused;
-    auto filesystem = OpenFileSystem(Type::SDMC, unused).Unwrap();
+    IFileSystem filesystem(OpenFileSystem(Type::SDMC).Unwrap());
 
     IPC::ResponseBuilder rb{ctx, 2, 0, 1};
     rb.Push(RESULT_SUCCESS);
@@ -531,8 +555,7 @@ void FSP_SRV::CreateSaveData(Kernel::HLERequestContext& ctx) {
 void FSP_SRV::MountSaveData(Kernel::HLERequestContext& ctx) {
     LOG_WARNING(Service_FS, "(STUBBED) called");
 
-    FileSys::Path unused;
-    auto filesystem = OpenFileSystem(Type::SaveData, unused).Unwrap();
+    IFileSystem filesystem(OpenFileSystem(Type::SaveData).Unwrap());
 
     IPC::ResponseBuilder rb{ctx, 2, 0, 1};
     rb.Push(RESULT_SUCCESS);
@@ -559,18 +582,11 @@ void FSP_SRV::OpenDataStorageByCurrentProcess(Kernel::HLERequestContext& ctx) {
         return;
     }
 
-    // Attempt to open a StorageBackend interface to the RomFS
-    auto storage = romfs->OpenFile({}, {});
-    if (storage.Failed()) {
-        LOG_CRITICAL(Service_FS, "no storage interface available!");
-        IPC::ResponseBuilder rb{ctx, 2};
-        rb.Push(storage.Code());
-        return;
-    }
+    IStorage storage(romfs);
 
     IPC::ResponseBuilder rb{ctx, 2, 0, 1};
     rb.Push(RESULT_SUCCESS);
-    rb.PushIpcInterface<IStorage>(std::move(storage.Unwrap()));
+    rb.PushIpcInterface<IStorage>(std::move(storage));
 }
 
 void FSP_SRV::OpenRomStorage(Kernel::HLERequestContext& ctx) {

src/core/hle/service/filesystem/fsp_srv.h

@@ -29,7 +29,7 @@ private:
     void OpenDataStorageByCurrentProcess(Kernel::HLERequestContext& ctx);
     void OpenRomStorage(Kernel::HLERequestContext& ctx);
 
-    std::unique_ptr<FileSys::FileSystemBackend> romfs;
+    FileSys::VirtualFile romfs;
 };
 
 } // namespace Service::FileSystem

src/core/loader/deconstructed_rom_directory.cpp

@@ -4,11 +4,10 @@
 
 #include <cinttypes>
 #include "common/common_funcs.h"
-#include "common/common_paths.h"
 #include "common/file_util.h"
 #include "common/logging/log.h"
 #include "common/string_util.h"
-#include "core/file_sys/romfs_factory.h"
+#include "core/file_sys/content_archive.h"
 #include "core/hle/kernel/process.h"
 #include "core/hle/kernel/resource_limit.h"
 #include "core/hle/service/filesystem/filesystem.h"
@@ -46,55 +45,11 @@ static std::string FindRomFS(const std::string& directory) {
     return filepath_romfs;
 }
 
-AppLoader_DeconstructedRomDirectory::AppLoader_DeconstructedRomDirectory(FileUtil::IOFile&& file,
-                                                                         std::string filepath)
-    : AppLoader(std::move(file)), filepath(std::move(filepath)) {}
-
-FileType AppLoader_DeconstructedRomDirectory::IdentifyType(FileUtil::IOFile& file,
-                                                           const std::string& filepath) {
-    bool is_main_found{};
-    bool is_npdm_found{};
-    bool is_rtld_found{};
-    bool is_sdk_found{};
-
-    const auto callback = [&](unsigned* num_entries_out, const std::string& directory,
-                              const std::string& virtual_name) -> bool {
-        // Skip directories
-        std::string physical_name = directory + virtual_name;
-        if (FileUtil::IsDirectory(physical_name)) {
-            return true;
-        }
-
-        // Verify filename
-        if (Common::ToLower(virtual_name) == "main") {
-            is_main_found = true;
-        } else if (Common::ToLower(virtual_name) == "main.npdm") {
-            is_npdm_found = true;
-            return true;
-        } else if (Common::ToLower(virtual_name) == "rtld") {
-            is_rtld_found = true;
-        } else if (Common::ToLower(virtual_name) == "sdk") {
-            is_sdk_found = true;
-        } else {
-            // Continue searching
-            return true;
-        }
-
-        // Verify file is an NSO
-        FileUtil::IOFile file(physical_name, "rb");
-        if (AppLoader_NSO::IdentifyType(file, physical_name) != FileType::NSO) {
-            return false;
-        }
-
-        // We are done if we've found and verified all required NSOs
-        return !(is_main_found && is_npdm_found && is_rtld_found && is_sdk_found);
-    };
-
-    // Search the directory recursively, looking for the required modules
-    const std::string directory = filepath.substr(0, filepath.find_last_of("/\\")) + DIR_SEP;
-    FileUtil::ForeachDirectoryEntry(nullptr, directory, callback);
+AppLoader_DeconstructedRomDirectory::AppLoader_DeconstructedRomDirectory(FileSys::VirtualFile file)
+    : AppLoader(std::move(file)) {}
 
-    if (is_main_found && is_npdm_found && is_rtld_found && is_sdk_found) {
+FileType AppLoader_DeconstructedRomDirectory::IdentifyType(const FileSys::VirtualFile& file) {
+    if (FileSys::IsDirectoryExeFS(file->GetContainingDirectory())) {
         return FileType::DeconstructedRomDirectory;
     }
 
@@ -106,14 +61,13 @@ ResultStatus AppLoader_DeconstructedRomDirectory::Load(
     if (is_loaded) {
         return ResultStatus::ErrorAlreadyLoaded;
     }
-    if (!file.IsOpen()) {
-        return ResultStatus::Error;
-    }
 
-    const std::string directory = filepath.substr(0, filepath.find_last_of("/\\")) + DIR_SEP;
-    const std::string npdm_path = directory + DIR_SEP + "main.npdm";
+    const FileSys::VirtualDir dir = file->GetContainingDirectory();
+    const FileSys::VirtualFile npdm = dir->GetFile("main.npdm");
+    if (npdm == nullptr)
+        return ResultStatus::ErrorInvalidFormat;
 
-    ResultStatus result = metadata.Load(npdm_path);
+    ResultStatus result = metadata.Load(npdm);
     if (result != ResultStatus::Success) {
         return result;
     }
@@ -128,9 +82,10 @@ ResultStatus AppLoader_DeconstructedRomDirectory::Load(
     VAddr next_load_addr{Memory::PROCESS_IMAGE_VADDR};
     for (const auto& module : {"rtld", "main", "subsdk0", "subsdk1", "subsdk2", "subsdk3",
                                "subsdk4", "subsdk5", "subsdk6", "subsdk7", "sdk"}) {
-        const std::string path = directory + DIR_SEP + module;
         const VAddr load_addr = next_load_addr;
-        next_load_addr = AppLoader_NSO::LoadModule(path, load_addr);
+        const FileSys::VirtualFile module_file = dir->GetFile(module);
+        if (module_file != nullptr)
+            next_load_addr = AppLoader_NSO::LoadModule(module_file, load_addr);
         if (next_load_addr) {
             LOG_DEBUG(Loader, "loaded module {} @ 0x{:X}", module, load_addr);
         } else {
@@ -147,41 +102,19 @@ ResultStatus AppLoader_DeconstructedRomDirectory::Load(
                  metadata.GetMainThreadStackSize());
 
     // Find the RomFS by searching for a ".romfs" file in this directory
-    filepath_romfs = FindRomFS(directory);
-
-    // Register the RomFS if a ".romfs" file was found
-    if (!filepath_romfs.empty()) {
-        Service::FileSystem::RegisterFileSystem(std::make_unique<FileSys::RomFS_Factory>(*this),
-                                                Service::FileSystem::Type::RomFS);
-    }
-
-    is_loaded = true;
-    return ResultStatus::Success;
-}
+    const auto& files = dir->GetFiles();
+    const auto romfs_iter =
+        std::find_if(files.begin(), files.end(), [](const FileSys::VirtualFile& file) {
+            return file->GetName().find(".romfs") != std::string::npos;
+        });
 
-ResultStatus AppLoader_DeconstructedRomDirectory::ReadRomFS(
-    std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset, u64& size) {
+    // TODO(DarkLordZach): Identify RomFS if its a subdirectory.
+    const auto romfs = (romfs_iter == files.end()) ? nullptr : *romfs_iter;
 
-    if (filepath_romfs.empty()) {
-        LOG_DEBUG(Loader, "No RomFS available");
-        return ResultStatus::ErrorNotUsed;
-    }
-
-    // We reopen the file, to allow its position to be independent
-    romfs_file = std::make_shared<FileUtil::IOFile>(filepath_romfs, "rb");
-    if (!romfs_file->IsOpen()) {
-        return ResultStatus::Error;
-    }
-
-    offset = 0;
-    size = romfs_file->GetSize();
-
-    LOG_DEBUG(Loader, "RomFS offset:           0x{:016X}", offset);
-    LOG_DEBUG(Loader, "RomFS size:             0x{:016X}", size);
-
-    // Reset read pointer
-    file.Seek(0, SEEK_SET);
+    if (romfs != nullptr)
+        Service::FileSystem::RegisterRomFS(romfs);
 
+    is_loaded = true;
     return ResultStatus::Success;
 }
 

src/core/loader/deconstructed_rom_directory.h

@@ -20,28 +20,22 @@ namespace Loader {
  */
 class AppLoader_DeconstructedRomDirectory final : public AppLoader {
 public:
-    AppLoader_DeconstructedRomDirectory(FileUtil::IOFile&& file, std::string filepath);
+    explicit AppLoader_DeconstructedRomDirectory(FileSys::VirtualFile main_file);
 
     /**
      * Returns the type of the file
-     * @param file FileUtil::IOFile open file
-     * @param filepath Path of the file that we are opening.
+     * @param file std::shared_ptr<VfsFile> open file
      * @return FileType found, or FileType::Error if this loader doesn't know it
      */
-    static FileType IdentifyType(FileUtil::IOFile& file, const std::string& filepath);
+    static FileType IdentifyType(const FileSys::VirtualFile& file);
 
     FileType GetFileType() override {
-        return IdentifyType(file, filepath);
+        return IdentifyType(file);
     }
 
     ResultStatus Load(Kernel::SharedPtr<Kernel::Process>& process) override;
 
-    ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
-                           u64& size) override;
-
 private:
-    std::string filepath_romfs;
-    std::string filepath;
     FileSys::ProgramMetadata metadata;
 };
 

src/core/loader/elf.cpp

@@ -365,20 +365,17 @@ SectionID ElfReader::GetSectionByName(const char* name, int firstSection) const
 
 namespace Loader {
 
-AppLoader_ELF::AppLoader_ELF(FileUtil::IOFile&& file, std::string filename)
-    : AppLoader(std::move(file)), filename(std::move(filename)) {}
+AppLoader_ELF::AppLoader_ELF(FileSys::VirtualFile file) : AppLoader(std::move(file)) {}
 
-FileType AppLoader_ELF::IdentifyType(FileUtil::IOFile& file, const std::string&) {
+FileType AppLoader_ELF::IdentifyType(const FileSys::VirtualFile& file) {
     static constexpr u16 ELF_MACHINE_ARM{0x28};
 
     u32 magic = 0;
-    file.Seek(0, SEEK_SET);
-    if (1 != file.ReadArray<u32>(&magic, 1))
+    if (4 != file->ReadObject(&magic))
         return FileType::Error;
 
     u16 machine = 0;
-    file.Seek(18, SEEK_SET);
-    if (1 != file.ReadArray<u16>(&machine, 1))
+    if (2 != file->ReadObject(&machine, 18))
         return FileType::Error;
 
     if (Common::MakeMagic('\x7f', 'E', 'L', 'F') == magic && ELF_MACHINE_ARM == machine)
@@ -391,20 +388,13 @@ ResultStatus AppLoader_ELF::Load(Kernel::SharedPtr<Kernel::Process>& process) {
     if (is_loaded)
         return ResultStatus::ErrorAlreadyLoaded;
 
-    if (!file.IsOpen())
-        return ResultStatus::Error;
-
-    // Reset read pointer in case this file has been read before.
-    file.Seek(0, SEEK_SET);
-
-    size_t size = file.GetSize();
-    std::unique_ptr<u8[]> buffer(new u8[size]);
-    if (file.ReadBytes(&buffer[0], size) != size)
+    std::vector<u8> buffer = file->ReadAllBytes();
+    if (buffer.size() != file->GetSize())
         return ResultStatus::Error;
 
     ElfReader elf_reader(&buffer[0]);
     SharedPtr<CodeSet> codeset = elf_reader.LoadInto(Memory::PROCESS_IMAGE_VADDR);
-    codeset->name = filename;
+    codeset->name = file->GetName();
 
     process->LoadModule(codeset, codeset->entrypoint);
     process->svc_access_mask.set();

src/core/loader/elf.h

@@ -16,24 +16,20 @@ namespace Loader {
 /// Loads an ELF/AXF file
 class AppLoader_ELF final : public AppLoader {
 public:
-    AppLoader_ELF(FileUtil::IOFile&& file, std::string filename);
+    explicit AppLoader_ELF(FileSys::VirtualFile file);
 
     /**
      * Returns the type of the file
-     * @param file FileUtil::IOFile open file
-     * @param filepath Path of the file that we are opening.
+     * @param file std::shared_ptr<VfsFile> open file
      * @return FileType found, or FileType::Error if this loader doesn't know it
      */
-    static FileType IdentifyType(FileUtil::IOFile& file, const std::string& filepath);
+    static FileType IdentifyType(const FileSys::VirtualFile& file);
 
     FileType GetFileType() override {
-        return IdentifyType(file, filename);
+        return IdentifyType(file);
     }
 
     ResultStatus Load(Kernel::SharedPtr<Kernel::Process>& process) override;
-
-private:
-    std::string filename;
 };
 
 } // namespace Loader

src/core/loader/loader.cpp

@@ -6,6 +6,7 @@
 #include <string>
 #include "common/logging/log.h"
 #include "common/string_util.h"
+#include "core/file_sys/vfs_real.h"
 #include "core/hle/kernel/process.h"
 #include "core/loader/deconstructed_rom_directory.h"
 #include "core/loader/elf.h"
@@ -21,11 +22,11 @@ const std::initializer_list<Kernel::AddressMapping> default_address_mappings = {
     {0x1F000000, 0x600000, false}, // entire VRAM
 };
 
-FileType IdentifyFile(FileUtil::IOFile& file, const std::string& filepath) {
+FileType IdentifyFile(FileSys::VirtualFile file) {
     FileType type;
 
 #define CHECK_TYPE(loader)                                                                         \
-    type = AppLoader_##loader::IdentifyType(file, filepath);                                       \
+    type = AppLoader_##loader::IdentifyType(file);                                                 \
     if (FileType::Error != type)                                                                   \
         return type;
 
@@ -41,25 +42,22 @@ FileType IdentifyFile(FileUtil::IOFile& file, const std::string& filepath) {
 }
 
 FileType IdentifyFile(const std::string& file_name) {
-    FileUtil::IOFile file(file_name, "rb");
-    if (!file.IsOpen()) {
-        LOG_ERROR(Loader, "Failed to load file {}", file_name);
-        return FileType::Unknown;
-    }
-
-    return IdentifyFile(file, file_name);
+    return IdentifyFile(FileSys::VirtualFile(std::make_shared<FileSys::RealVfsFile>(file_name)));
 }
 
-FileType GuessFromExtension(const std::string& extension_) {
-    std::string extension = Common::ToLower(extension_);
+FileType GuessFromFilename(const std::string& name) {
+    if (name == "main")
+        return FileType::DeconstructedRomDirectory;
 
-    if (extension == ".elf")
+    const std::string extension = Common::ToLower(FileUtil::GetExtensionFromFilename(name));
+
+    if (extension == "elf")
         return FileType::ELF;
-    else if (extension == ".nro")
+    if (extension == "nro")
         return FileType::NRO;
-    else if (extension == ".nso")
+    if (extension == "nso")
         return FileType::NSO;
-    else if (extension == ".nca")
+    if (extension == "nca")
         return FileType::NCA;
 
     return FileType::Unknown;
@@ -93,58 +91,47 @@ const char* GetFileTypeString(FileType type) {
  * @param filepath the file full path (with name)
  * @return std::unique_ptr<AppLoader> a pointer to a loader object;  nullptr for unsupported type
  */
-static std::unique_ptr<AppLoader> GetFileLoader(FileUtil::IOFile&& file, FileType type,
-                                                const std::string& filename,
-                                                const std::string& filepath) {
+static std::unique_ptr<AppLoader> GetFileLoader(FileSys::VirtualFile file, FileType type) {
     switch (type) {
 
     // Standard ELF file format.
     case FileType::ELF:
-        return std::make_unique<AppLoader_ELF>(std::move(file), filename);
+        return std::make_unique<AppLoader_ELF>(std::move(file));
 
     // NX NSO file format.
     case FileType::NSO:
-        return std::make_unique<AppLoader_NSO>(std::move(file), filepath);
+        return std::make_unique<AppLoader_NSO>(std::move(file));
 
     // NX NRO file format.
     case FileType::NRO:
-        return std::make_unique<AppLoader_NRO>(std::move(file), filepath);
+        return std::make_unique<AppLoader_NRO>(std::move(file));
 
     // NX NCA file format.
     case FileType::NCA:
-        return std::make_unique<AppLoader_NCA>(std::move(file), filepath);
+        return std::make_unique<AppLoader_NCA>(std::move(file));
 
     // NX deconstructed ROM directory.
     case FileType::DeconstructedRomDirectory:
-        return std::make_unique<AppLoader_DeconstructedRomDirectory>(std::move(file), filepath);
+        return std::make_unique<AppLoader_DeconstructedRomDirectory>(std::move(file));
 
     default:
         return nullptr;
     }
 }
 
-std::unique_ptr<AppLoader> GetLoader(const std::string& filename) {
-    FileUtil::IOFile file(filename, "rb");
-    if (!file.IsOpen()) {
-        LOG_ERROR(Loader, "Failed to load file {}", filename);
-        return nullptr;
-    }
-
-    std::string filename_filename, filename_extension;
-    Common::SplitPath(filename, nullptr, &filename_filename, &filename_extension);
-
-    FileType type = IdentifyFile(file, filename);
-    FileType filename_type = GuessFromExtension(filename_extension);
+std::unique_ptr<AppLoader> GetLoader(FileSys::VirtualFile file) {
+    FileType type = IdentifyFile(file);
+    FileType filename_type = GuessFromFilename(file->GetName());
 
     if (type != filename_type) {
-        LOG_WARNING(Loader, "File {} has a different type than its extension.", filename);
+        LOG_WARNING(Loader, "File {} has a different type than its extension.", file->GetName());
         if (FileType::Unknown == type)
             type = filename_type;
     }
 
-    LOG_DEBUG(Loader, "Loading file {} as {}...", filename, GetFileTypeString(type));
+    LOG_DEBUG(Loader, "Loading file {} as {}...", file->GetName(), GetFileTypeString(type));
 
-    return GetFileLoader(std::move(file), type, filename_filename, filename);
+    return GetFileLoader(std::move(file), type);
 }
 
 } // namespace Loader

src/core/loader/loader.h

@@ -13,6 +13,7 @@
 #include <boost/optional.hpp>
 #include "common/common_types.h"
 #include "common/file_util.h"
+#include "core/file_sys/vfs.h"
 #include "core/hle/kernel/kernel.h"
 
 namespace Kernel {
@@ -36,10 +37,9 @@ enum class FileType {
 /**
  * Identifies the type of a bootable file based on the magic value in its header.
  * @param file open file
- * @param filepath Path of the file that we are opening.
  * @return FileType of file
  */
-FileType IdentifyFile(FileUtil::IOFile& file, const std::string& filepath);
+FileType IdentifyFile(FileSys::VirtualFile file);
 
 /**
  * Identifies the type of a bootable file based on the magic value in its header.
@@ -50,12 +50,12 @@ FileType IdentifyFile(FileUtil::IOFile& file, const std::string& filepath);
 FileType IdentifyFile(const std::string& file_name);
 
 /**
- * Guess the type of a bootable file from its extension
- * @param extension String extension of bootable file
+ * Guess the type of a bootable file from its name
+ * @param name String name of bootable file
  * @return FileType of file. Note: this will return FileType::Unknown if it is unable to determine
  * a filetype, and will never return FileType::Error.
  */
-FileType GuessFromExtension(const std::string& extension);
+FileType GuessFromFilename(const std::string& name);
 
 /**
  * Convert a FileType into a string which can be displayed to the user.
@@ -79,7 +79,7 @@ enum class ResultStatus {
 /// Interface for loading an application
 class AppLoader : NonCopyable {
 public:
-    AppLoader(FileUtil::IOFile&& file) : file(std::move(file)) {}
+    AppLoader(FileSys::VirtualFile file) : file(std::move(file)) {}
     virtual ~AppLoader() {}
 
     /**
@@ -154,26 +154,20 @@ public:
     /**
      * Get the RomFS of the application
      * Since the RomFS can be huge, we return a file reference instead of copying to a buffer
-     * @param romfs_file The file containing the RomFS
-     * @param offset The offset the romfs begins on
-     * @param size The size of the romfs
+     * @param file The file containing the RomFS
      * @return ResultStatus result of function
      */
-    virtual ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
-                                   u64& size) {
+    virtual ResultStatus ReadRomFS(FileSys::VirtualFile& dir) {
         return ResultStatus::ErrorNotImplemented;
     }
 
     /**
      * Get the update RomFS of the application
      * Since the RomFS can be huge, we return a file reference instead of copying to a buffer
-     * @param romfs_file The file containing the RomFS
-     * @param offset The offset the romfs begins on
-     * @param size The size of the romfs
+     * @param file The file containing the RomFS
      * @return ResultStatus result of function
      */
-    virtual ResultStatus ReadUpdateRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
-                                         u64& size) {
+    virtual ResultStatus ReadUpdateRomFS(FileSys::VirtualFile& file) {
         return ResultStatus::ErrorNotImplemented;
     }
 
@@ -187,7 +181,7 @@ public:
     }
 
 protected:
-    FileUtil::IOFile file;
+    FileSys::VirtualFile file;
     bool is_loaded = false;
 };
 
@@ -202,6 +196,6 @@ extern const std::initializer_list<Kernel::AddressMapping> default_address_mappi
  * @param filename String filename of bootable file
  * @return best loader for this file
  */
-std::unique_ptr<AppLoader> GetLoader(const std::string& filename);
+std::unique_ptr<AppLoader> GetLoader(FileSys::VirtualFile file);
 
 } // namespace Loader

src/core/loader/nca.cpp

@@ -4,13 +4,11 @@
 
 #include <vector>
 
-#include "common/common_funcs.h"
 #include "common/file_util.h"
 #include "common/logging/log.h"
-#include "common/swap.h"
 #include "core/core.h"
+#include "core/file_sys/content_archive.h"
 #include "core/file_sys/program_metadata.h"
-#include "core/file_sys/romfs_factory.h"
 #include "core/hle/kernel/process.h"
 #include "core/hle/kernel/resource_limit.h"
 #include "core/hle/service/filesystem/filesystem.h"
@@ -20,208 +18,15 @@
 
 namespace Loader {
 
-// Media offsets in headers are stored divided by 512. Mult. by this to get real offset.
-constexpr u64 MEDIA_OFFSET_MULTIPLIER = 0x200;
-
-constexpr u64 SECTION_HEADER_SIZE = 0x200;
-constexpr u64 SECTION_HEADER_OFFSET = 0x400;
-
-enum class NcaContentType : u8 { Program = 0, Meta = 1, Control = 2, Manual = 3, Data = 4 };
-
-enum class NcaSectionFilesystemType : u8 { PFS0 = 0x2, ROMFS = 0x3 };
-
-struct NcaSectionTableEntry {
-    u32_le media_offset;
-    u32_le media_end_offset;
-    INSERT_PADDING_BYTES(0x8);
-};
-static_assert(sizeof(NcaSectionTableEntry) == 0x10, "NcaSectionTableEntry has incorrect size.");
-
-struct NcaHeader {
-    std::array<u8, 0x100> rsa_signature_1;
-    std::array<u8, 0x100> rsa_signature_2;
-    u32_le magic;
-    u8 is_system;
-    NcaContentType content_type;
-    u8 crypto_type;
-    u8 key_index;
-    u64_le size;
-    u64_le title_id;
-    INSERT_PADDING_BYTES(0x4);
-    u32_le sdk_version;
-    u8 crypto_type_2;
-    INSERT_PADDING_BYTES(15);
-    std::array<u8, 0x10> rights_id;
-    std::array<NcaSectionTableEntry, 0x4> section_tables;
-    std::array<std::array<u8, 0x20>, 0x4> hash_tables;
-    std::array<std::array<u8, 0x10>, 0x4> key_area;
-    INSERT_PADDING_BYTES(0xC0);
-};
-static_assert(sizeof(NcaHeader) == 0x400, "NcaHeader has incorrect size.");
-
-struct NcaSectionHeaderBlock {
-    INSERT_PADDING_BYTES(3);
-    NcaSectionFilesystemType filesystem_type;
-    u8 crypto_type;
-    INSERT_PADDING_BYTES(3);
-};
-static_assert(sizeof(NcaSectionHeaderBlock) == 0x8, "NcaSectionHeaderBlock has incorrect size.");
-
-struct Pfs0Superblock {
-    NcaSectionHeaderBlock header_block;
-    std::array<u8, 0x20> hash;
-    u32_le size;
-    INSERT_PADDING_BYTES(4);
-    u64_le hash_table_offset;
-    u64_le hash_table_size;
-    u64_le pfs0_header_offset;
-    u64_le pfs0_size;
-    INSERT_PADDING_BYTES(432);
-};
-static_assert(sizeof(Pfs0Superblock) == 0x200, "Pfs0Superblock has incorrect size.");
-
-static bool IsValidNca(const NcaHeader& header) {
-    return header.magic == Common::MakeMagic('N', 'C', 'A', '2') ||
-           header.magic == Common::MakeMagic('N', 'C', 'A', '3');
-}
-
-// TODO(DarkLordZach): Add support for encrypted.
-class Nca final {
-    std::vector<FileSys::PartitionFilesystem> pfs;
-    std::vector<u64> pfs_offset;
-
-    u64 romfs_offset = 0;
-    u64 romfs_size = 0;
-
-    boost::optional<u8> exefs_id = boost::none;
-
-    FileUtil::IOFile file;
-    std::string path;
-
-    u64 GetExeFsFileOffset(const std::string& file_name) const;
-    u64 GetExeFsFileSize(const std::string& file_name) const;
-
-public:
-    ResultStatus Load(FileUtil::IOFile&& file, std::string path);
-
-    FileSys::PartitionFilesystem GetPfs(u8 id) const;
-
-    u64 GetRomFsOffset() const;
-    u64 GetRomFsSize() const;
-
-    std::vector<u8> GetExeFsFile(const std::string& file_name);
-};
-
-static bool IsPfsExeFs(const FileSys::PartitionFilesystem& pfs) {
-    // According to switchbrew, an exefs must only contain these two files:
-    return pfs.GetFileSize("main") > 0 && pfs.GetFileSize("main.npdm") > 0;
-}
-
-ResultStatus Nca::Load(FileUtil::IOFile&& in_file, std::string in_path) {
-    file = std::move(in_file);
-    path = in_path;
-    file.Seek(0, SEEK_SET);
-    std::array<u8, sizeof(NcaHeader)> header_array{};
-    if (sizeof(NcaHeader) != file.ReadBytes(header_array.data(), sizeof(NcaHeader)))
-        LOG_CRITICAL(Loader, "File reader errored out during header read.");
-
-    NcaHeader header{};
-    std::memcpy(&header, header_array.data(), sizeof(NcaHeader));
-    if (!IsValidNca(header))
-        return ResultStatus::ErrorInvalidFormat;
-
-    int number_sections =
-        std::count_if(std::begin(header.section_tables), std::end(header.section_tables),
-                      [](NcaSectionTableEntry entry) { return entry.media_offset > 0; });
-
-    for (int i = 0; i < number_sections; ++i) {
-        // Seek to beginning of this section.
-        file.Seek(SECTION_HEADER_OFFSET + i * SECTION_HEADER_SIZE, SEEK_SET);
-        std::array<u8, sizeof(NcaSectionHeaderBlock)> array{};
-        if (sizeof(NcaSectionHeaderBlock) !=
-            file.ReadBytes(array.data(), sizeof(NcaSectionHeaderBlock)))
-            LOG_CRITICAL(Loader, "File reader errored out during header read.");
-
-        NcaSectionHeaderBlock block{};
-        std::memcpy(&block, array.data(), sizeof(NcaSectionHeaderBlock));
-
-        if (block.filesystem_type == NcaSectionFilesystemType::ROMFS) {
-            romfs_offset = header.section_tables[i].media_offset * MEDIA_OFFSET_MULTIPLIER;
-            romfs_size =
-                header.section_tables[i].media_end_offset * MEDIA_OFFSET_MULTIPLIER - romfs_offset;
-        } else if (block.filesystem_type == NcaSectionFilesystemType::PFS0) {
-            Pfs0Superblock sb{};
-            // Seek back to beginning of this section.
-            file.Seek(SECTION_HEADER_OFFSET + i * SECTION_HEADER_SIZE, SEEK_SET);
-            if (sizeof(Pfs0Superblock) != file.ReadBytes(&sb, sizeof(Pfs0Superblock)))
-                LOG_CRITICAL(Loader, "File reader errored out during header read.");
-
-            u64 offset = (static_cast<u64>(header.section_tables[i].media_offset) *
-                          MEDIA_OFFSET_MULTIPLIER) +
-                         sb.pfs0_header_offset;
-            FileSys::PartitionFilesystem npfs{};
-            ResultStatus status = npfs.Load(path, offset);
-
-            if (status == ResultStatus::Success) {
-                pfs.emplace_back(std::move(npfs));
-                pfs_offset.emplace_back(offset);
-            }
-        }
-    }
-
-    for (size_t i = 0; i < pfs.size(); ++i) {
-        if (IsPfsExeFs(pfs[i]))
-            exefs_id = i;
-    }
-
-    return ResultStatus::Success;
-}
-
-FileSys::PartitionFilesystem Nca::GetPfs(u8 id) const {
-    return pfs[id];
-}
-
-u64 Nca::GetExeFsFileOffset(const std::string& file_name) const {
-    if (exefs_id == boost::none)
-        return 0;
-    return pfs[*exefs_id].GetFileOffset(file_name) + pfs_offset[*exefs_id];
-}
-
-u64 Nca::GetExeFsFileSize(const std::string& file_name) const {
-    if (exefs_id == boost::none)
-        return 0;
-    return pfs[*exefs_id].GetFileSize(file_name);
-}
-
-u64 Nca::GetRomFsOffset() const {
-    return romfs_offset;
-}
-
-u64 Nca::GetRomFsSize() const {
-    return romfs_size;
-}
-
-std::vector<u8> Nca::GetExeFsFile(const std::string& file_name) {
-    std::vector<u8> out(GetExeFsFileSize(file_name));
-    file.Seek(GetExeFsFileOffset(file_name), SEEK_SET);
-    file.ReadBytes(out.data(), GetExeFsFileSize(file_name));
-    return out;
-}
-
-AppLoader_NCA::AppLoader_NCA(FileUtil::IOFile&& file, std::string filepath)
-    : AppLoader(std::move(file)), filepath(std::move(filepath)) {}
-
-FileType AppLoader_NCA::IdentifyType(FileUtil::IOFile& file, const std::string&) {
-    file.Seek(0, SEEK_SET);
-    std::array<u8, 0x400> header_enc_array{};
-    if (0x400 != file.ReadBytes(header_enc_array.data(), 0x400))
-        return FileType::Error;
+AppLoader_NCA::AppLoader_NCA(FileSys::VirtualFile file) : AppLoader(file) {}
 
+FileType AppLoader_NCA::IdentifyType(const FileSys::VirtualFile& file) {
     // TODO(DarkLordZach): Assuming everything is decrypted. Add crypto support.
-    NcaHeader header{};
-    std::memcpy(&header, header_enc_array.data(), sizeof(NcaHeader));
+    FileSys::NCAHeader header{};
+    if (sizeof(FileSys::NCAHeader) != file->ReadObject(&header))
+        return FileType::Error;
 
-    if (IsValidNca(header) && header.content_type == NcaContentType::Program)
+    if (IsValidNCA(header) && header.content_type == FileSys::NCAContentType::Program)
         return FileType::NCA;
 
     return FileType::Error;
@@ -231,17 +36,22 @@ ResultStatus AppLoader_NCA::Load(Kernel::SharedPtr<Kernel::Process>& process) {
     if (is_loaded) {
         return ResultStatus::ErrorAlreadyLoaded;
     }
-    if (!file.IsOpen()) {
-        return ResultStatus::Error;
-    }
 
-    nca = std::make_unique<Nca>();
-    ResultStatus result = nca->Load(std::move(file), filepath);
+    nca = std::make_unique<FileSys::NCA>(file);
+    ResultStatus result = nca->GetStatus();
     if (result != ResultStatus::Success) {
         return result;
     }
 
-    result = metadata.Load(nca->GetExeFsFile("main.npdm"));
+    if (nca->GetType() != FileSys::NCAContentType::Program)
+        return ResultStatus::ErrorInvalidFormat;
+
+    auto exefs = nca->GetExeFS();
+
+    if (exefs == nullptr)
+        return ResultStatus::ErrorInvalidFormat;
+
+    result = metadata.Load(exefs->GetFile("main.npdm"));
     if (result != ResultStatus::Success) {
         return result;
     }
@@ -256,7 +66,8 @@ ResultStatus AppLoader_NCA::Load(Kernel::SharedPtr<Kernel::Process>& process) {
     for (const auto& module : {"rtld", "main", "subsdk0", "subsdk1", "subsdk2", "subsdk3",
                                "subsdk4", "subsdk5", "subsdk6", "subsdk7", "sdk"}) {
         const VAddr load_addr = next_load_addr;
-        next_load_addr = AppLoader_NSO::LoadModule(module, nca->GetExeFsFile(module), load_addr);
+
+        next_load_addr = AppLoader_NSO::LoadModule(exefs->GetFile(module), load_addr);
         if (next_load_addr) {
             LOG_DEBUG(Loader, "loaded module {} @ 0x{:X}", module, load_addr);
         } else {
@@ -272,28 +83,11 @@ ResultStatus AppLoader_NCA::Load(Kernel::SharedPtr<Kernel::Process>& process) {
     process->Run(Memory::PROCESS_IMAGE_VADDR, metadata.GetMainThreadPriority(),
                  metadata.GetMainThreadStackSize());
 
-    if (nca->GetRomFsSize() > 0)
-        Service::FileSystem::RegisterFileSystem(std::make_unique<FileSys::RomFS_Factory>(*this),
-                                                Service::FileSystem::Type::RomFS);
-
     is_loaded = true;
-    return ResultStatus::Success;
-}
-
-ResultStatus AppLoader_NCA::ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
-                                      u64& size) {
-    if (nca->GetRomFsSize() == 0) {
-        LOG_DEBUG(Loader, "No RomFS available");
-        return ResultStatus::ErrorNotUsed;
-    }
-
-    romfs_file = std::make_shared<FileUtil::IOFile>(filepath, "rb");
-
-    offset = nca->GetRomFsOffset();
-    size = nca->GetRomFsSize();
 
-    LOG_DEBUG(Loader, "RomFS offset:           0x{:016X}", offset);
-    LOG_DEBUG(Loader, "RomFS size:             0x{:016X}", size);
+    const auto romfs = nca->GetRomFS();
+    if (romfs != nullptr)
+        Service::FileSystem::RegisterRomFS(romfs);
 
     return ResultStatus::Success;
 }

src/core/loader/nca.h

@@ -6,44 +6,37 @@
 
 #include <string>
 #include "common/common_types.h"
-#include "core/file_sys/partition_filesystem.h"
+#include "core/file_sys/content_archive.h"
 #include "core/file_sys/program_metadata.h"
 #include "core/hle/kernel/kernel.h"
 #include "core/loader/loader.h"
 
 namespace Loader {
 
-class Nca;
-
 /// Loads an NCA file
 class AppLoader_NCA final : public AppLoader {
 public:
-    AppLoader_NCA(FileUtil::IOFile&& file, std::string filepath);
+    explicit AppLoader_NCA(FileSys::VirtualFile file);
 
     /**
      * Returns the type of the file
-     * @param file FileUtil::IOFile open file
-     * @param filepath Path of the file that we are opening.
+     * @param file std::shared_ptr<VfsFile> open file
      * @return FileType found, or FileType::Error if this loader doesn't know it
      */
-    static FileType IdentifyType(FileUtil::IOFile& file, const std::string& filepath);
+    static FileType IdentifyType(const FileSys::VirtualFile& file);
 
     FileType GetFileType() override {
-        return IdentifyType(file, filepath);
+        return IdentifyType(file);
     }
 
     ResultStatus Load(Kernel::SharedPtr<Kernel::Process>& process) override;
 
-    ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset,
-                           u64& size) override;
-
     ~AppLoader_NCA();
 
 private:
-    std::string filepath;
     FileSys::ProgramMetadata metadata;
 
-    std::unique_ptr<Nca> nca;
+    std::unique_ptr<FileSys::NCA> nca;
 };
 
 } // namespace Loader

src/core/loader/nro.cpp

@@ -47,14 +47,12 @@ struct ModHeader {
 };
 static_assert(sizeof(ModHeader) == 0x1c, "ModHeader has incorrect size.");
 
-AppLoader_NRO::AppLoader_NRO(FileUtil::IOFile&& file, std::string filepath)
-    : AppLoader(std::move(file)), filepath(std::move(filepath)) {}
+AppLoader_NRO::AppLoader_NRO(FileSys::VirtualFile file) : AppLoader(file) {}
 
-FileType AppLoader_NRO::IdentifyType(FileUtil::IOFile& file, const std::string&) {
+FileType AppLoader_NRO::IdentifyType(const FileSys::VirtualFile& file) {
     // Read NSO header
     NroHeader nro_header{};
-    file.Seek(0, SEEK_SET);
-    if (sizeof(NroHeader) != file.ReadBytes(&nro_header, sizeof(NroHeader))) {
+    if (sizeof(NroHeader) != file->ReadObject(&nro_header)) {
         return FileType::Error;
     }
     if (nro_header.magic == Common::MakeMagic('N', 'R', 'O', '0')) {
@@ -67,16 +65,10 @@ static constexpr u32 PageAlignSize(u32 size) {
     return (size + Memory::PAGE_MASK) & ~Memory::PAGE_MASK;
 }
 
-bool AppLoader_NRO::LoadNro(const std::string& path, VAddr load_base) {
-    FileUtil::IOFile file(path, "rb");
-    if (!file.IsOpen()) {
-        return {};
-    }
-
+bool AppLoader_NRO::LoadNro(FileSys::VirtualFile file, VAddr load_base) {
     // Read NSO header
     NroHeader nro_header{};
-    file.Seek(0, SEEK_SET);
-    if (sizeof(NroHeader) != file.ReadBytes(&nro_header, sizeof(NroHeader))) {
+    if (sizeof(NroHeader) != file->ReadObject(&nro_header)) {
         return {};
     }
     if (nro_header.magic != Common::MakeMagic('N', 'R', 'O', '0')) {
@@ -85,10 +77,9 @@ bool AppLoader_NRO::LoadNro(const std::string& path, VAddr load_base) {
 
     // Build program image
     Kernel::SharedPtr<Kernel::CodeSet> codeset = Kernel::CodeSet::Create("");
-    std::vector<u8> program_image;
-    program_image.resize(PageAlignSize(nro_header.file_size));
-    file.Seek(0, SEEK_SET);
-    file.ReadBytes(program_image.data(), nro_header.file_size);
+    std::vector<u8> program_image = file->ReadBytes(PageAlignSize(nro_header.file_size));
+    if (program_image.size() != PageAlignSize(nro_header.file_size))
+        return {};
 
     for (int i = 0; i < nro_header.segments.size(); ++i) {
         codeset->segments[i].addr = nro_header.segments[i].offset;
@@ -111,7 +102,7 @@ bool AppLoader_NRO::LoadNro(const std::string& path, VAddr load_base) {
     program_image.resize(static_cast<u32>(program_image.size()) + bss_size);
 
     // Load codeset for current process
-    codeset->name = path;
+    codeset->name = file->GetName();
     codeset->memory = std::make_shared<std::vector<u8>>(std::move(program_image));
     Core::CurrentProcess()->LoadModule(codeset, load_base);
 
@@ -122,14 +113,11 @@ ResultStatus AppLoader_NRO::Load(Kernel::SharedPtr<Kernel::Process>& process) {
     if (is_loaded) {
         return ResultStatus::ErrorAlreadyLoaded;
     }
-    if (!file.IsOpen()) {
-        return ResultStatus::Error;
-    }
 
     // Load NRO
     static constexpr VAddr base_addr{Memory::PROCESS_IMAGE_VADDR};
 
-    if (!LoadNro(filepath, base_addr)) {
+    if (!LoadNro(file, base_addr)) {
         return ResultStatus::ErrorInvalidFormat;
     }
 

src/core/loader/nro.h

@@ -15,26 +15,23 @@ namespace Loader {
 /// Loads an NRO file
 class AppLoader_NRO final : public AppLoader, Linker {
 public:
-    AppLoader_NRO(FileUtil::IOFile&& file, std::string filepath);
+    AppLoader_NRO(FileSys::VirtualFile file);
 
     /**
      * Returns the type of the file
-     * @param file FileUtil::IOFile open file
-     * @param filepath Path of the file that we are opening.
+     * @param file std::shared_ptr<VfsFile> open file
      * @return FileType found, or FileType::Error if this loader doesn't know it
      */
-    static FileType IdentifyType(FileUtil::IOFile& file, const std::string& filepath);
+    static FileType IdentifyType(const FileSys::VirtualFile& file);
 
     FileType GetFileType() override {
-        return IdentifyType(file, filepath);
+        return IdentifyType(file);
     }
 
     ResultStatus Load(Kernel::SharedPtr<Kernel::Process>& process) override;
 
 private:
-    bool LoadNro(const std::string& path, VAddr load_base);
-
-    std::string filepath;
+    bool LoadNro(FileSys::VirtualFile file, VAddr load_base);
 };
 
 } // namespace Loader

src/core/loader/nso.cpp

@@ -37,6 +37,7 @@ struct NsoHeader {
     std::array<u32_le, 3> segments_compressed_size;
 };
 static_assert(sizeof(NsoHeader) == 0x6c, "NsoHeader has incorrect size.");
+static_assert(std::is_trivially_copyable_v<NsoHeader>, "NsoHeader isn't trivially copyable.");
 
 struct ModHeader {
     u32_le magic;
@@ -49,15 +50,11 @@ struct ModHeader {
 };
 static_assert(sizeof(ModHeader) == 0x1c, "ModHeader has incorrect size.");
 
-AppLoader_NSO::AppLoader_NSO(FileUtil::IOFile&& file, std::string filepath)
-    : AppLoader(std::move(file)), filepath(std::move(filepath)) {}
+AppLoader_NSO::AppLoader_NSO(FileSys::VirtualFile file) : AppLoader(std::move(file)) {}
 
-FileType AppLoader_NSO::IdentifyType(FileUtil::IOFile& file, const std::string&) {
+FileType AppLoader_NSO::IdentifyType(const FileSys::VirtualFile& file) {
     u32 magic = 0;
-    file.Seek(0, SEEK_SET);
-    if (1 != file.ReadArray<u32>(&magic, 1)) {
-        return FileType::Error;
-    }
+    file->ReadObject(&magic);
 
     if (Common::MakeMagic('N', 'S', 'O', '0') == magic) {
         return FileType::NSO;
@@ -98,80 +95,27 @@ static constexpr u32 PageAlignSize(u32 size) {
     return (size + Memory::PAGE_MASK) & ~Memory::PAGE_MASK;
 }
 
-VAddr AppLoader_NSO::LoadModule(const std::string& name, const std::vector<u8>& file_data,
-                                VAddr load_base) {
-    if (file_data.size() < sizeof(NsoHeader))
+VAddr AppLoader_NSO::LoadModule(FileSys::VirtualFile file, VAddr load_base) {
+    if (file == nullptr)
         return {};
 
-    NsoHeader nso_header;
-    std::memcpy(&nso_header, file_data.data(), sizeof(NsoHeader));
-
-    if (nso_header.magic != Common::MakeMagic('N', 'S', 'O', '0'))
+    if (file->GetSize() < sizeof(NsoHeader))
         return {};
 
-    // Build program image
-    Kernel::SharedPtr<Kernel::CodeSet> codeset = Kernel::CodeSet::Create("");
-    std::vector<u8> program_image;
-    for (int i = 0; i < nso_header.segments.size(); ++i) {
-        std::vector<u8> compressed_data(nso_header.segments_compressed_size[i]);
-        for (int j = 0; j < nso_header.segments_compressed_size[i]; ++j)
-            compressed_data[j] = file_data[nso_header.segments[i].offset + j];
-        std::vector<u8> data = DecompressSegment(compressed_data, nso_header.segments[i]);
-        program_image.resize(nso_header.segments[i].location);
-        program_image.insert(program_image.end(), data.begin(), data.end());
-        codeset->segments[i].addr = nso_header.segments[i].location;
-        codeset->segments[i].offset = nso_header.segments[i].location;
-        codeset->segments[i].size = PageAlignSize(static_cast<u32>(data.size()));
-    }
-
-    // MOD header pointer is at .text offset + 4
-    u32 module_offset;
-    std::memcpy(&module_offset, program_image.data() + 4, sizeof(u32));
-
-    // Read MOD header
-    ModHeader mod_header{};
-    // Default .bss to size in segment header if MOD0 section doesn't exist
-    u32 bss_size{PageAlignSize(nso_header.segments[2].bss_size)};
-    std::memcpy(&mod_header, program_image.data() + module_offset, sizeof(ModHeader));
-    const bool has_mod_header{mod_header.magic == Common::MakeMagic('M', 'O', 'D', '0')};
-    if (has_mod_header) {
-        // Resize program image to include .bss section and page align each section
-        bss_size = PageAlignSize(mod_header.bss_end_offset - mod_header.bss_start_offset);
-    }
-    codeset->data.size += bss_size;
-    const u32 image_size{PageAlignSize(static_cast<u32>(program_image.size()) + bss_size)};
-    program_image.resize(image_size);
-
-    // Load codeset for current process
-    codeset->name = name;
-    codeset->memory = std::make_shared<std::vector<u8>>(std::move(program_image));
-    Core::CurrentProcess()->LoadModule(codeset, load_base);
-
-    return load_base + image_size;
-}
-
-VAddr AppLoader_NSO::LoadModule(const std::string& path, VAddr load_base) {
-    FileUtil::IOFile file(path, "rb");
-    if (!file.IsOpen()) {
-        return {};
-    }
-
-    // Read NSO header
     NsoHeader nso_header{};
-    file.Seek(0, SEEK_SET);
-    if (sizeof(NsoHeader) != file.ReadBytes(&nso_header, sizeof(NsoHeader))) {
+    if (sizeof(NsoHeader) != file->ReadObject(&nso_header))
         return {};
-    }
-    if (nso_header.magic != Common::MakeMagic('N', 'S', 'O', '0')) {
+
+    if (nso_header.magic != Common::MakeMagic('N', 'S', 'O', '0'))
         return {};
-    }
 
     // Build program image
     Kernel::SharedPtr<Kernel::CodeSet> codeset = Kernel::CodeSet::Create("");
     std::vector<u8> program_image;
     for (int i = 0; i < nso_header.segments.size(); ++i) {
-        std::vector<u8> data =
-            ReadSegment(file, nso_header.segments[i], nso_header.segments_compressed_size[i]);
+        const std::vector<u8> compressed_data =
+            file->ReadBytes(nso_header.segments_compressed_size[i], nso_header.segments[i].offset);
+        std::vector<u8> data = DecompressSegment(compressed_data, nso_header.segments[i]);
         program_image.resize(nso_header.segments[i].location);
         program_image.insert(program_image.end(), data.begin(), data.end());
         codeset->segments[i].addr = nso_header.segments[i].location;
@@ -198,7 +142,7 @@ VAddr AppLoader_NSO::LoadModule(const std::string& path, VAddr load_base) {
     program_image.resize(image_size);
 
     // Load codeset for current process
-    codeset->name = path;
+    codeset->name = file->GetName();
     codeset->memory = std::make_shared<std::vector<u8>>(std::move(program_image));
     Core::CurrentProcess()->LoadModule(codeset, load_base);
 
@@ -209,13 +153,10 @@ ResultStatus AppLoader_NSO::Load(Kernel::SharedPtr<Kernel::Process>& process) {
     if (is_loaded) {
         return ResultStatus::ErrorAlreadyLoaded;
     }
-    if (!file.IsOpen()) {
-        return ResultStatus::Error;
-    }
 
     // Load module
-    LoadModule(filepath, Memory::PROCESS_IMAGE_VADDR);
-    LOG_DEBUG(Loader, "loaded module {} @ 0x{:X}", filepath, Memory::PROCESS_IMAGE_VADDR);
+    LoadModule(file, Memory::PROCESS_IMAGE_VADDR);
+    LOG_DEBUG(Loader, "loaded module {} @ 0x{:X}", file->GetName(), Memory::PROCESS_IMAGE_VADDR);
 
     process->svc_access_mask.set();
     process->address_mappings = default_address_mappings;

src/core/loader/nso.h

@@ -15,29 +15,22 @@ namespace Loader {
 /// Loads an NSO file
 class AppLoader_NSO final : public AppLoader, Linker {
 public:
-    AppLoader_NSO(FileUtil::IOFile&& file, std::string filepath);
+    explicit AppLoader_NSO(FileSys::VirtualFile file);
 
     /**
      * Returns the type of the file
-     * @param file FileUtil::IOFile open file
-     * @param filepath Path of the file that we are opening.
+     * @param file std::shared_ptr<VfsFile> open file
      * @return FileType found, or FileType::Error if this loader doesn't know it
      */
-    static FileType IdentifyType(FileUtil::IOFile& file, const std::string& filepath);
+    static FileType IdentifyType(const FileSys::VirtualFile& file);
 
     FileType GetFileType() override {
-        return IdentifyType(file, filepath);
+        return IdentifyType(file);
     }
 
-    static VAddr LoadModule(const std::string& name, const std::vector<u8>& file_data,
-                            VAddr load_base);
-
-    static VAddr LoadModule(const std::string& path, VAddr load_base);
+    static VAddr LoadModule(FileSys::VirtualFile file, VAddr load_base);
 
     ResultStatus Load(Kernel::SharedPtr<Kernel::Process>& process) override;
-
-private:
-    std::string filepath;
 };
 
 } // namespace Loader

src/yuzu/game_list.cpp

@@ -12,6 +12,7 @@
 #include "common/common_paths.h"
 #include "common/logging/log.h"
 #include "common/string_util.h"
+#include "core/file_sys/vfs_real.h"
 #include "core/loader/loader.h"
 #include "game_list.h"
 #include "game_list_p.h"
@@ -404,7 +405,8 @@ void GameListWorker::AddFstEntriesToGameList(const std::string& dir_path, unsign
         bool is_dir = FileUtil::IsDirectory(physical_name);
         if (!is_dir &&
             (HasSupportedFileExtension(physical_name) || IsExtractedNCAMain(physical_name))) {
-            std::unique_ptr<Loader::AppLoader> loader = Loader::GetLoader(physical_name);
+            std::unique_ptr<Loader::AppLoader> loader =
+                Loader::GetLoader(std::make_shared<FileSys::RealVfsFile>(physical_name));
             if (!loader)
                 return true;