2 files changed, 132 insertions, 0 deletions

diff --git a/src/core/file_sys/patch_manager.cpp b/src/core/file_sys/patch_manager.cpp
new file mode 100644
index 000000000..697b8a4c9
--- /dev/null
+++ b/src/core/file_sys/patch_manager.cpp
@@ -0,0 +1,90 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "core/file_sys/patch_manager.h"
+#include "core/file_sys/registered_cache.h"
+#include "core/hle/service/filesystem/filesystem.h"
+
+namespace FileSys {
+
+union TitleVersion {
+    u32 version;
+
+    struct {
+        u8 v_revision;
+        u8 v_micro;
+        u8 v_minor;
+        u8 v_major;
+    };
+};
+
+std::string FormatTitleVersion(u32 version_, bool full) {
+    TitleVersion ver{};
+    ver.version = version_;
+
+    if (full)
+        return fmt::format("v{}.{}.{}.{}", ver.v_major, ver.v_minor, ver.v_minor, ver.v_revision);
+    return fmt::format("v{}.{}.{}", ver.v_major, ver.v_minor, ver.v_micro);
+}
+
+constexpr std::array<const char*, 1> PATCH_TYPE_NAMES{
+    "Update",
+};
+
+std::string FormatPatchTypeName(PatchType type) {
+    return PATCH_TYPE_NAMES.at(static_cast<size_t>(type));
+}
+
+PatchManager::PatchManager(u64 title_id) : title_id(title_id) {}
+
+VirtualDir PatchManager::PatchExeFS(VirtualDir exefs) const {
+    if (exefs == nullptr)
+        return exefs;
+
+    const auto installed = Service::FileSystem::GetUnionContents();
+
+    // Game Updates
+    const auto update_tid = GetUpdateTitleID(title_id);
+    const auto update = installed->GetEntry(update_tid, ContentRecordType::Program);
+    if (update != nullptr) {
+        if (update->GetStatus() == Loader::ResultStatus::ErrorMissingBKTRBaseRomFS &&
+            update->GetExeFS() != nullptr)
+            exefs = update->GetExeFS();
+    }
+
+    return exefs;
+}
+
+VirtualFile PatchManager::PatchRomFS(VirtualFile romfs) const {
+    if (romfs == nullptr)
+        return romfs;
+
+    const auto installed = Service::FileSystem::GetUnionContents();
+
+    // Game Updates
+    const auto update_tid = GetUpdateTitleID(title_id);
+    const auto update = installed->GetEntryRaw(update_tid, ContentRecordType::Program);
+    if (update != nullptr) {
+        const auto nca = std::make_shared<NCA>(update, romfs);
+        if (nca->GetStatus() == Loader::ResultStatus::Success && nca->GetRomFS() != nullptr)
+            romfs = nca->GetRomFS();
+    }
+
+    return romfs;
+}
+
+std::map<PatchType, u32> PatchManager::GetPatchVersionNames() const {
+    std::map<PatchType, u32> out;
+    const auto installed = Service::FileSystem::GetUnionContents();
+
+    const auto update_tid = GetUpdateTitleID(title_id);
+    const auto update_version = installed->GetEntryVersion(update_tid);
+    if (update_version != boost::none &&
+        installed->HasEntry(update_tid, ContentRecordType::Program))
+        out[PatchType::Update] = update_version.get();
+
+    return out;
+}
+
+} // namespace FileSys
diff --git a/src/core/file_sys/patch_manager.h b/src/core/file_sys/patch_manager.h
new file mode 100644
index 000000000..2a39c473a
--- /dev/null
+++ b/src/core/file_sys/patch_manager.h
@@ -0,0 +1,42 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <map>
+#include "common/common_types.h"
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+std::string FormatTitleVersion(u32 version, bool full = false);
+
+enum class PatchType {
+    Update,
+};
+
+std::string FormatPatchTypeName(PatchType type);
+
+// A centralized class to manage patches to games.
+class PatchManager {
+public:
+    explicit PatchManager(u64 title_id);
+
+    // Currently tracked ExeFS patches:
+    // - Game Updates
+    VirtualDir PatchExeFS(VirtualDir exefs) const;
+
+    // Currently tracked RomFS patches:
+    // - Game Updates
+    VirtualFile PatchRomFS(VirtualFile romfs) const;
+
+    // Returns a vector of pairs between patch names and patch versions.
+    // i.e. Update v80 will return {Update, 80}
+    std::map<PatchType, u32> GetPatchVersionNames() const;
+
+private:
+    u64 title_id;
+};
+
+} // namespace FileSys