Merge pull request #833 from Ryex/advanced_copy_instance

.github/workflows/build.yml

@@ -400,7 +400,7 @@ jobs:
           if (Get-Content ./codesign.pfx){
             cd ${{ env.INSTALL_DIR }}
             # We ship the exact same executable for portable and non-portable editions, so signing just once is fine
-            SignTool sign /fd sha256 /td sha256 /f ../codesign.pfx /p '${{ secrets.WINDOWS_CODESIGN_PASSWORD }}' /tr http://timestamp.digicert.com prismlauncher.exe
+            SignTool sign /fd sha256 /td sha256 /f ../codesign.pfx /p '${{ secrets.WINDOWS_CODESIGN_PASSWORD }}' /tr http://timestamp.digicert.com prismlauncher.exe prismlauncher_filelink.exe
           } else {
             ":warning: Skipped code signing for Windows, as certificate was not present." >> $env:GITHUB_STEP_SUMMARY
           }

.gitignore

@@ -12,6 +12,8 @@ html/
 CMakeLists.txt.user
 CMakeLists.txt.user.*
 CMakeSettings.json
+/CMakeFiles
+CMakeCache.txt
 /.project
 /.settings
 /.idea

launcher/BaseInstance.cpp

@@ -40,6 +40,8 @@
 #include <QDir>
 #include <QDebug>
 #include <QRegularExpression>
+#include <QJsonDocument>
+#include <QJsonObject>
 
 #include "settings/INISettingsObject.h"
 #include "settings/Setting.h"
@@ -64,6 +66,8 @@ BaseInstance::BaseInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr s
     m_settings->registerSetting("totalTimePlayed", 0);
     m_settings->registerSetting("lastTimePlayed", 0);
 
+    m_settings->registerSetting("linkedInstances", "[]");
+
     // Game time override
     auto gameTimeOverride = m_settings->registerSetting("OverrideGameTime", false);
     m_settings->registerOverride(globalSettings->getSetting("ShowGameTime"), gameTimeOverride);
@@ -182,6 +186,38 @@ bool BaseInstance::shouldStopOnConsoleOverflow() const
     return m_settings->get("ConsoleOverflowStop").toBool();
 }
 
+QStringList BaseInstance::getLinkedInstances() const
+{
+    return m_settings->get("linkedInstances").toStringList();
+}
+
+void BaseInstance::setLinkedInstances(const QStringList& list)
+{
+    auto linkedInstances = m_settings->get("linkedInstances").toStringList();
+    m_settings->set("linkedInstances", list);
+}
+
+void BaseInstance::addLinkedInstanceId(const QString& id)
+{
+    auto linkedInstances = m_settings->get("linkedInstances").toStringList();
+    linkedInstances.append(id);
+    setLinkedInstances(linkedInstances);
+}
+
+bool BaseInstance::removeLinkedInstanceId(const QString& id)
+{
+    auto linkedInstances = m_settings->get("linkedInstances").toStringList();
+    int numRemoved = linkedInstances.removeAll(id);
+    setLinkedInstances(linkedInstances);
+    return numRemoved > 0;
+}
+
+bool BaseInstance::isLinkedToInstanceId(const QString& id) const
+{
+    auto linkedInstances = m_settings->get("linkedInstances").toStringList();
+    return linkedInstances.contains(id);
+}
+
 void BaseInstance::iconUpdated(QString key)
 {
     if(iconKey() == key)

launcher/BaseInstance.h

@@ -282,6 +282,12 @@ public:
     int getConsoleMaxLines() const;
     bool shouldStopOnConsoleOverflow() const;
 
+    QStringList getLinkedInstances() const;
+    void setLinkedInstances(const QStringList& list);
+    void addLinkedInstanceId(const QString& id);
+    bool removeLinkedInstanceId(const QString& id);
+    bool isLinkedToInstanceId(const QString& id) const;
+
 protected:
     void changeStatus(Status newStatus);
 

launcher/CMakeLists.txt

@@ -26,6 +26,7 @@ set(CORE_SOURCES
     MMCZip.cpp
     StringUtils.h
     StringUtils.cpp
+    QVariantUtils.h
     RuntimeContext.h
 
     # Basic instance manipulation tasks (derived from InstanceTask)
@@ -552,6 +553,18 @@ set(ATLAUNCHER_SOURCES
     modplatform/atlauncher/ATLShareCode.h
 )
 
+set(LINKEXE_SOURCES
+    filelink/FileLink.h
+    filelink/FileLink.cpp
+    FileSystem.h
+    FileSystem.cpp
+    Exception.h
+    StringUtils.h
+    StringUtils.cpp
+    DesktopServices.h
+    DesktopServices.cpp
+)
+
 ######## Logging categories ########
 
 ecm_qt_declare_logging_category(CORE_SOURCES
@@ -1091,6 +1104,41 @@ install(TARGETS ${Launcher_Name}
     FRAMEWORK DESTINATION ${FRAMEWORK_DEST_DIR} COMPONENT Runtime
 )
 
+if(WIN32)
+    add_library(filelink_logic STATIC ${LINKEXE_SOURCES})
+    target_include_directories(filelink_logic PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+    target_link_libraries(filelink_logic
+        systeminfo
+        BuildConfig
+        ghcFilesystem::ghc_filesystem
+        Qt${QT_VERSION_MAJOR}::Widgets
+        Qt${QT_VERSION_MAJOR}::Core
+        Qt${QT_VERSION_MAJOR}::Network
+        # Qt${QT_VERSION_MAJOR}::Concurrent
+        ${Launcher_QT_LIBS}
+    )
+
+    add_executable("${Launcher_Name}_filelink" WIN32 filelink/main.cpp)
+
+    target_sources("${Launcher_Name}_filelink" PRIVATE filelink/filelink.exe.manifest)
+
+    target_link_libraries("${Launcher_Name}_filelink" filelink_logic)
+
+    if(DEFINED Launcher_APP_BINARY_NAME)
+        set_target_properties("${Launcher_Name}_filelink" PROPERTIES OUTPUT_NAME "${Launcher_APP_BINARY_NAME}_filelink")
+    endif()
+    if(DEFINED Launcher_BINARY_RPATH)
+        SET_TARGET_PROPERTIES("${Launcher_Name}_filelink" PROPERTIES INSTALL_RPATH "${Launcher_BINARY_RPATH}")
+    endif()
+
+    install(TARGETS "${Launcher_Name}_filelink"
+        BUNDLE DESTINATION "." COMPONENT Runtime
+        LIBRARY DESTINATION ${LIBRARY_DEST_DIR} COMPONENT Runtime
+        RUNTIME DESTINATION ${BINARY_DEST_DIR} COMPONENT Runtime
+        FRAMEWORK DESTINATION ${FRAMEWORK_DEST_DIR} COMPONENT Runtime
+    )
+endif()
+
 if (UNIX AND APPLE)
     # Add Sparkle updater
     # It has to be copied here instead of just allowing fixup_bundle to install it, otherwise essential parts of

launcher/DesktopServices.cpp

@@ -37,7 +37,6 @@
 #include <QDesktopServices>
 #include <QProcess>
 #include <QDebug>
-#include "Application.h"
 
 /**
  * This shouldn't exist, but until QTBUG-9328 and other unreported bugs are fixed, it needs to be a thing.

launcher/FileSystem.h

@@ -3,6 +3,7 @@
  *  Prism Launcher - Minecraft Launcher
  *  Copyright (C) 2022 Sefa Eyeoglu <contact@scrumplex.net>
  *  Copyright (C) 2022 TheKodeToad <TheKodeToad@proton.me>
+ *  Copyright (C) 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -39,9 +40,13 @@
 #include "Exception.h"
 #include "pathmatcher/IPathMatcher.h"
 
+#include <system_error>
+
 #include <QDir>
 #include <QFlags>
+#include <QLocalServer>
 #include <QObject>
+#include <QThread>
 
 namespace FS {
 
@@ -77,7 +82,9 @@ bool ensureFilePathExists(QString filenamepath);
  */
 bool ensureFolderPathExists(QString filenamepath);
 
-/// @brief Copies a directory and it's contents from src to dest
+/**
+ * @brief Copies a directory and it's contents from src to dest
+ */
 class copy : public QObject {
     Q_OBJECT
    public:
@@ -122,6 +129,127 @@ class copy : public QObject {
     int m_copied;
 };
 
+struct LinkPair {
+    QString src;
+    QString dst;
+};
+
+struct LinkResult {
+    QString src;
+    QString dst;
+    QString err_msg;
+    int err_value;
+};
+
+class ExternalLinkFileProcess : public QThread {
+    Q_OBJECT
+   public:
+    ExternalLinkFileProcess(QString server, bool useHardLinks, QObject* parent = nullptr)
+        : QThread(parent), m_useHardLinks(useHardLinks), m_server(server)
+    {}
+
+    void run() override
+    {
+        runLinkFile();
+        emit processExited();
+    }
+
+   signals:
+    void processExited();
+
+   private:
+    void runLinkFile();
+
+    bool m_useHardLinks = false;
+
+    QString m_server;
+};
+
+/**
+ * @brief links (a file / a directory and it's contents) from src to dest
+ */
+class create_link : public QObject {
+    Q_OBJECT
+   public:
+    create_link(const QList<LinkPair> path_pairs, QObject* parent = nullptr) : QObject(parent) { m_path_pairs.append(path_pairs); }
+    create_link(const QString& src, const QString& dst, QObject* parent = nullptr) : QObject(parent)
+    {
+        LinkPair pair = { src, dst };
+        m_path_pairs.append(pair);
+    }
+    create_link& useHardLinks(const bool useHard)
+    {
+        m_useHardLinks = useHard;
+        return *this;
+    }
+    create_link& matcher(const IPathMatcher* filter)
+    {
+        m_matcher = filter;
+        return *this;
+    }
+    create_link& whitelist(bool whitelist)
+    {
+        m_whitelist = whitelist;
+        return *this;
+    }
+    create_link& linkRecursively(bool recursive)
+    {
+        m_recursive = recursive;
+        return *this;
+    }
+    create_link& setMaxDepth(int depth)
+    {
+        m_max_depth = depth;
+        return *this;
+    }
+    create_link& debug(bool d)
+    {
+        m_debug = d;
+        return *this;
+    }
+
+    std::error_code getOSError() { return m_os_err; }
+
+    bool operator()(bool dryRun = false) { return operator()(QString(), dryRun); }
+
+    int totalLinked() { return m_linked; }
+
+    void runPrivileged() { runPrivileged(QString()); }
+    void runPrivileged(const QString& offset);
+
+    QList<LinkResult> getResults() { return m_path_results; }
+
+   signals:
+    void fileLinked(const QString& srcName, const QString& dstName);
+    void linkFailed(const QString& srcName, const QString& dstName, const QString& err_msg, int err_value);
+    void finished();
+    void finishedPrivileged(bool gotResults);
+
+   private:
+    bool operator()(const QString& offset, bool dryRun = false);
+    void make_link_list(const QString& offset);
+    bool make_links();
+
+   private:
+    bool m_useHardLinks = false;
+    const IPathMatcher* m_matcher = nullptr;
+    bool m_whitelist = false;
+    bool m_recursive = true;
+
+    /// @brief >= -1 = infinite, 0 = link files at src/* to dest/*, 1 = link files at src/*/* to dest/*/*, etc.
+    int m_max_depth = -1;
+
+    QList<LinkPair> m_path_pairs;
+    QList<LinkResult> m_path_results;
+    QList<LinkPair> m_links_to_make;
+
+    int m_linked;
+    bool m_debug = false;
+    std::error_code m_os_err;
+
+    QLocalServer m_linkServer;
+};
+
 /**
  * @brief moves a file by renaming it
  * @param source source file path
@@ -138,13 +266,30 @@ bool deletePath(QString path);
 /**
  * Trash a folder / file
  */
-bool trash(QString path, QString *pathInTrash = nullptr);
+bool trash(QString path, QString* pathInTrash = nullptr);
 
 QString PathCombine(const QString& path1, const QString& path2);
 QString PathCombine(const QString& path1, const QString& path2, const QString& path3);
 QString PathCombine(const QString& path1, const QString& path2, const QString& path3, const QString& path4);
 
-QString AbsolutePath(QString path);
+QString AbsolutePath(const QString& path);
+
+/**
+ * @brief depth of path. "foo.txt" -> 0 , "bar/foo.txt" -> 1, /baz/bar/foo.txt -> 2, etc.
+ *
+ * @param path path to measure
+ * @return int number of components before base path
+ */
+int pathDepth(const QString& path);
+
+/**
+ * @brief  cut off segments of path until it is a max of length depth
+ *
+ * @param path path to truncate
+ * @param depth max depth of new path
+ * @return QString truncated path
+ */
+QString pathTruncate(const QString& path, int depth);
 
 /**
  * Resolve an executable
@@ -186,4 +331,194 @@ bool overrideFolder(QString overwritten_path, QString override_path);
  * Creates a shortcut to the specified target file at the specified destination path.
  */
 bool createShortcut(QString destination, QString target, QStringList args, QString name, QString icon);
-}
+
+enum class FilesystemType {
+    FAT,
+    NTFS,
+    REFS,
+    EXT,
+    EXT_2_OLD,
+    EXT_2_3_4,
+    XFS,
+    BTRFS,
+    NFS,
+    ZFS,
+    APFS,
+    HFS,
+    HFSPLUS,
+    HFSX,
+    FUSEBLK,
+    F2FS,
+    UNKNOWN
+};
+
+/**
+ * @brief Ordered Mapping of enum types to reported filesystem names
+ * this mapping is non exsaustive, it just attempts to capture the filesystems which could be reasonalbly be in use .
+ * all string values are in uppercase, use `QString.toUpper()` or equivalent during lookup.
+ *
+ * QMap is ordered
+ *
+ */
+static const QMap<FilesystemType, QStringList> s_filesystem_type_names = {
+    {FilesystemType::FAT,        { "FAT" }},
+    {FilesystemType::NTFS,       { "NTFS" }},
+    {FilesystemType::REFS,       { "REFS" }},
+    {FilesystemType::EXT_2_OLD,  { "EXT_2_OLD", "EXT2_OLD" }},
+    {FilesystemType::EXT_2_3_4,  { "EXT2/3/4", "EXT_2_3_4", "EXT2", "EXT3", "EXT4" }},
+    {FilesystemType::EXT,        { "EXT" }},
+    {FilesystemType::XFS,        { "XFS" }},
+    {FilesystemType::BTRFS,      { "BTRFS" }},
+    {FilesystemType::NFS,        { "NFS" }},
+    {FilesystemType::ZFS,        { "ZFS" }},
+    {FilesystemType::APFS,       { "APFS" }},
+    {FilesystemType::HFS,        { "HFS" }},
+    {FilesystemType::HFSPLUS,    { "HFSPLUS" }},
+    {FilesystemType::HFSX,       { "HFSX" }},
+    {FilesystemType::FUSEBLK,    { "FUSEBLK" }},
+    {FilesystemType::F2FS,       { "F2FS" }},
+    {FilesystemType::UNKNOWN,    { "UNKNOWN" }}
+};
+
+/**
+ * @brief Get the string name of Filesystem enum object
+ *
+ * @param type
+ * @return QString
+ */
+QString getFilesystemTypeName(FilesystemType type);
+
+/**
+ * @brief Get the Filesystem enum object from a name
+ *  Does a lookup of the type name and returns an exact match
+ *
+ * @param name
+ * @return FilesystemType
+ */
+FilesystemType getFilesystemType(const QString& name);
+
+/**
+ * @brief Get the Filesystem enum object from a name
+ *  Does a fuzzy lookup of the type name and returns an apropreate match
+ *
+ * @param name
+ * @return FilesystemType
+ */
+FilesystemType getFilesystemTypeFuzzy(const QString& name);
+
+struct FilesystemInfo {
+    FilesystemType fsType = FilesystemType::UNKNOWN;
+    QString fsTypeName;
+    int blockSize;
+    qint64 bytesAvailable;
+    qint64 bytesFree;
+    qint64 bytesTotal;
+    QString name;
+    QString rootPath;
+};
+
+/**
+ * @brief path to the near ancestor that exists
+ *
+ */
+QString nearestExistentAncestor(const QString& path);
+
+/**
+ * @brief colect information about the filesystem under a file
+ *
+ */
+FilesystemInfo statFS(const QString& path);
+
+static const QList<FilesystemType> s_clone_filesystems = { FilesystemType::BTRFS, FilesystemType::APFS, FilesystemType::ZFS,
+                                                           FilesystemType::XFS, FilesystemType::REFS };
+
+/**
+ * @brief if the Filesystem is reflink/clone capable
+ *
+ */
+bool canCloneOnFS(const QString& path);
+bool canCloneOnFS(const FilesystemInfo& info);
+bool canCloneOnFS(FilesystemType type);
+
+/**
+ * @brief if the Filesystems are reflink/clone capable and both are on the same device
+ *
+ */
+bool canClone(const QString& src, const QString& dst);
+
+/**
+ * @brief Copies a directory and it's contents from src to dest
+ */
+class clone : public QObject {
+    Q_OBJECT
+   public:
+    clone(const QString& src, const QString& dst, QObject* parent = nullptr) : QObject(parent)
+    {
+        m_src.setPath(src);
+        m_dst.setPath(dst);
+    }
+    clone& matcher(const IPathMatcher* filter)
+    {
+        m_matcher = filter;
+        return *this;
+    }
+    clone& whitelist(bool whitelist)
+    {
+        m_whitelist = whitelist;
+        return *this;
+    }
+
+    bool operator()(bool dryRun = false) { return operator()(QString(), dryRun); }
+
+    int totalCloned() { return m_cloned; }
+
+   signals:
+    void fileCloned(const QString& src, const QString& dst);
+    void cloneFailed(const QString& src, const QString& dst);
+
+   private:
+    bool operator()(const QString& offset, bool dryRun = false);
+
+   private:
+    const IPathMatcher* m_matcher = nullptr;
+    bool m_whitelist = false;
+    QDir m_src;
+    QDir m_dst;
+    int m_cloned;
+};
+
+/**
+ * @brief clone/reflink file from src to dst
+ *
+ */
+bool clone_file(const QString& src, const QString& dst, std::error_code& ec);
+
+#if defined(Q_OS_WIN)
+bool win_ioctl_clone(const std::wstring& src_path, const std::wstring& dst_path, std::error_code& ec);
+#elif defined(Q_OS_LINUX)
+bool linux_ficlone(const std::string& src_path, const std::string& dst_path, std::error_code& ec);
+#elif defined(Q_OS_MACOS) || defined(Q_OS_FREEBSD) || defined(Q_OS_OPENBSD)
+bool macos_bsd_clonefile(const std::string& src_path, const std::string& dst_path, std::error_code& ec);
+#endif
+
+static const QList<FilesystemType> s_non_link_filesystems = {
+    FilesystemType::FAT,
+};
+
+/**
+ * @brief if the Filesystem is symlink capable
+ *
+ */
+bool canLinkOnFS(const QString& path);
+bool canLinkOnFS(const FilesystemInfo& info);
+bool canLinkOnFS(FilesystemType type);
+
+/**
+ * @brief if the Filesystem is symlink capable on both ends
+ *
+ */
+bool canLink(const QString& src, const QString& dst);
+
+uintmax_t hardLinkCount(const QString& path);
+
+}  // namespace FS

launcher/InstanceCopyPrefs.cpp

@@ -16,8 +16,13 @@ bool InstanceCopyPrefs::allTrue() const
         copyScreenshots;
 }
 
+
 // Returns a single RegEx string of the selected folders/files to filter out (ex: ".minecraft/saves|.minecraft/server.dat")
 QString InstanceCopyPrefs::getSelectedFiltersAsRegex() const
+{
+    return getSelectedFiltersAsRegex({});
+}
+QString InstanceCopyPrefs::getSelectedFiltersAsRegex(const QStringList& additionalFilters) const
 {
     QStringList filters;
 
@@ -42,6 +47,10 @@ QString InstanceCopyPrefs::getSelectedFiltersAsRegex() const
     if(!copyScreenshots)
         filters << "screenshots";
 
+    for (auto filter : additionalFilters) {
+        filters << filter;
+    }
+
     // If we have any filters to add, join them as a single regex string to return:
     if (!filters.isEmpty()) {
         const QString MC_ROOT = "[.]?minecraft/";
@@ -93,6 +102,31 @@ bool InstanceCopyPrefs::isCopyScreenshotsEnabled() const
     return copyScreenshots;
 }
 
+bool InstanceCopyPrefs::isUseSymLinksEnabled() const
+{
+    return useSymLinks;
+}
+
+bool InstanceCopyPrefs::isUseHardLinksEnabled() const
+{
+    return useHardLinks;
+}
+
+bool InstanceCopyPrefs::isLinkRecursivelyEnabled() const
+{
+    return linkRecursively;
+}
+
+bool InstanceCopyPrefs::isDontLinkSavesEnabled() const
+{
+    return dontLinkSaves;
+}
+
+bool InstanceCopyPrefs::isUseCloneEnabled() const
+{
+    return useClone;
+}
+
 // ======= Setters =======
 void InstanceCopyPrefs::enableCopySaves(bool b)
 {
@@ -133,3 +167,28 @@ void InstanceCopyPrefs::enableCopyScreenshots(bool b)
 {
     copyScreenshots = b;
 }
+
+void InstanceCopyPrefs::enableUseSymLinks(bool b)
+{
+    useSymLinks = b;
+}
+
+void InstanceCopyPrefs::enableLinkRecursively(bool b)
+{
+    linkRecursively = b;
+}
+
+void InstanceCopyPrefs::enableUseHardLinks(bool b)
+{
+    useHardLinks = b;
+}
+
+void InstanceCopyPrefs::enableDontLinkSaves(bool b)
+{
+    dontLinkSaves = b;
+}
+
+void InstanceCopyPrefs::enableUseClone(bool b)
+{
+    useClone = b;
+}

launcher/InstanceCopyPrefs.h

@@ -10,6 +10,7 @@ struct InstanceCopyPrefs {
    public:
     [[nodiscard]] bool allTrue() const;
     [[nodiscard]] QString getSelectedFiltersAsRegex() const;
+    [[nodiscard]] QString getSelectedFiltersAsRegex(const QStringList& additionalFilters) const;
     // Getters
     [[nodiscard]] bool isCopySavesEnabled() const;
     [[nodiscard]] bool isKeepPlaytimeEnabled() const;
@@ -19,6 +20,11 @@ struct InstanceCopyPrefs {
     [[nodiscard]] bool isCopyServersEnabled() const;
     [[nodiscard]] bool isCopyModsEnabled() const;
     [[nodiscard]] bool isCopyScreenshotsEnabled() const;
+    [[nodiscard]] bool isUseSymLinksEnabled() const;
+    [[nodiscard]] bool isLinkRecursivelyEnabled() const;
+    [[nodiscard]] bool isUseHardLinksEnabled() const;
+    [[nodiscard]] bool isDontLinkSavesEnabled() const;
+    [[nodiscard]] bool isUseCloneEnabled() const;
     // Setters
     void enableCopySaves(bool b);
     void enableKeepPlaytime(bool b);
@@ -28,6 +34,11 @@ struct InstanceCopyPrefs {
     void enableCopyServers(bool b);
     void enableCopyMods(bool b);
     void enableCopyScreenshots(bool b);
+    void enableUseSymLinks(bool b);
+    void enableLinkRecursively(bool b);
+    void enableUseHardLinks(bool b);
+    void enableDontLinkSaves(bool b);
+    void enableUseClone(bool b);
 
    protected: // data
     bool copySaves = true;
@@ -38,4 +49,9 @@ struct InstanceCopyPrefs {
     bool copyServers = true;
     bool copyMods = true;
     bool copyScreenshots = true;
+    bool useSymLinks = false;
+    bool linkRecursively = false;
+    bool useHardLinks = false;
+    bool dontLinkSaves = false;
+    bool useClone = false;
 };

launcher/InstanceCopyTask.cpp

@@ -1,18 +1,31 @@
 #include "InstanceCopyTask.h"
-#include "settings/INISettingsObject.h"
+#include <QDebug>
+#include <QtConcurrentRun>
 #include "FileSystem.h"
 #include "NullInstance.h"
 #include "pathmatcher/RegexpMatcher.h"
-#include <QtConcurrentRun>
+#include "settings/INISettingsObject.h"
 
 InstanceCopyTask::InstanceCopyTask(InstancePtr origInstance, const InstanceCopyPrefs& prefs)
 {
     m_origInstance = origInstance;
     m_keepPlaytime = prefs.isKeepPlaytimeEnabled();
+    m_useLinks = prefs.isUseSymLinksEnabled();
+    m_linkRecursively = prefs.isLinkRecursivelyEnabled();
+    m_useHardLinks = prefs.isLinkRecursivelyEnabled() && prefs.isUseHardLinksEnabled();
+    m_copySaves = prefs.isLinkRecursivelyEnabled() && prefs.isDontLinkSavesEnabled() && prefs.isCopySavesEnabled();
+    m_useClone = prefs.isUseCloneEnabled();
 
     QString filters = prefs.getSelectedFiltersAsRegex();
+    if (m_useLinks || m_useHardLinks) {
         if (!filters.isEmpty())
-    {
+            filters += "|";
+        filters += "instance.cfg";
+    }
+
+    qDebug() << "CopyFilters:" << filters;
+
+    if (!filters.isEmpty()) {
         // Set regex filter:
         // FIXME: get this from the original instance type...
         auto matcherReal = new RegexpMatcher(filters);
@@ -25,11 +38,78 @@ void InstanceCopyTask::executeTask()
 {
     setStatus(tr("Copying instance %1").arg(m_origInstance->name()));
 
-    m_copyFuture = QtConcurrent::run(QThreadPool::globalInstance(), [this]{
+    auto copySaves = [&]() {
+        FS::copy savesCopy(FS::PathCombine(m_origInstance->instanceRoot(), "saves"), FS::PathCombine(m_stagingPath, "saves"));
+        savesCopy.followSymlinks(true);
+
+        return savesCopy();
+    };
+
+    m_copyFuture = QtConcurrent::run(QThreadPool::globalInstance(), [this, copySaves] {
+        if (m_useClone) {
+            FS::clone folderClone(m_origInstance->instanceRoot(), m_stagingPath);
+            folderClone.matcher(m_matcher.get());
+
+            return folderClone();
+        } else if (m_useLinks || m_useHardLinks) {
+            FS::create_link folderLink(m_origInstance->instanceRoot(), m_stagingPath);
+            int depth = m_linkRecursively ? -1 : 0;  // we need to at least link the top level instead of the instance folder
+            folderLink.linkRecursively(true).setMaxDepth(depth).useHardLinks(m_useHardLinks).matcher(m_matcher.get());
+
+            bool there_were_errors = false;
+
+            if (!folderLink()) {
+#if defined Q_OS_WIN32
+                if (!m_useHardLinks) {
+                    qDebug() << "EXPECTED: Link failure, Windows requires permissions for symlinks";
+
+                    qDebug() << "attempting to run with privelage";
+
+                    QEventLoop loop;
+                    bool got_priv_results = false;
+
+                    connect(&folderLink, &FS::create_link::finishedPrivileged, this, [&](bool gotResults) {
+                        if (!gotResults) {
+                            qDebug() << "Privileged run exited without results!";
+                        }
+                        got_priv_results = gotResults;
+                        loop.quit();
+                    });
+                    folderLink.runPrivileged();
+
+                    loop.exec();  // wait for the finished signal
+
+                    for (auto result : folderLink.getResults()) {
+                        if (result.err_value != 0) {
+                            there_were_errors = true;
+                        }
+                    }
+
+                    if (m_copySaves) {
+                        there_were_errors |= !copySaves();
+                    }
+
+                    return got_priv_results && !there_were_errors;
+                } else {
+                    qDebug() << "Link Failed!" << folderLink.getOSError().value() << folderLink.getOSError().message().c_str();
+                }
+#else
+                qDebug() << "Link Failed!" << folderLink.getOSError().value() << folderLink.getOSError().message().c_str();
+#endif
+                return false;
+            }
+
+            if (m_copySaves) {
+                there_were_errors |= !copySaves();
+            }
+
+            return !there_were_errors;
+        } else {
             FS::copy folderCopy(m_origInstance->instanceRoot(), m_stagingPath);
             folderCopy.followSymlinks(false).matcher(m_matcher.get());
 
             return folderCopy();
+        }
     });
     connect(&m_copyFutureWatcher, &QFutureWatcher<bool>::finished, this, &InstanceCopyTask::copyFinished);
     connect(&m_copyFutureWatcher, &QFutureWatcher<bool>::canceled, this, &InstanceCopyTask::copyAborted);
@@ -39,8 +119,7 @@ void InstanceCopyTask::executeTask()
 void InstanceCopyTask::copyFinished()
 {
     auto successful = m_copyFuture.result();
-    if(!successful)
+    if (!successful) {
-    {
         emitFailed(tr("Instance folder copy failed."));
         return;
     }
@@ -50,9 +129,11 @@ void InstanceCopyTask::copyFinished()
     InstancePtr inst(new NullInstance(m_globalSettings, instanceSettings, m_stagingPath));
     inst->setName(name());
     inst->setIconKey(m_instIcon);
-    if(!m_keepPlaytime) {
+    if (!m_keepPlaytime) {
         inst->resetTimePlayed();
     }
+    if (m_useLinks)
+        inst->addLinkedInstanceId(m_origInstance->id());
     emitSucceeded();
 }
 

launcher/InstanceCopyTask.h

@@ -30,4 +30,9 @@ private:
     QFutureWatcher<bool> m_copyFutureWatcher;
     std::unique_ptr<IPathMatcher> m_matcher;
     bool m_keepPlaytime;
+    bool m_useLinks = false;
+    bool m_useHardLinks = false;
+    bool m_copySaves = false;
+    bool m_linkRecursively = false;
+    bool m_useClone = false;
 };

launcher/InstanceList.cpp

@@ -129,6 +129,16 @@ QMimeData* InstanceList::mimeData(const QModelIndexList& indexes) const
     return mimeData;
 }
 
+QStringList InstanceList::getLinkedInstancesById(const QString &id) const
+{
+    QStringList linkedInstances;
+    for (auto inst : m_instances) {
+        if (inst->isLinkedToInstanceId(id))
+            linkedInstances.append(inst->id());
+    }
+    return linkedInstances;
+}
+
 int InstanceList::rowCount(const QModelIndex& parent) const
 {
     Q_UNUSED(parent);
@@ -865,7 +875,7 @@ Task* InstanceList::wrapInstanceTask(InstanceTask* task)
 
 QString InstanceList::getStagedInstancePath()
 {
-    QString key = QUuid::createUuid().toString();
+    QString key = QUuid::createUuid().toString(QUuid::WithoutBraces);
     QString tempDir = ".LAUNCHER_TEMP/";
     QString relPath = FS::PathCombine(tempDir, key);
     QDir rootPath(m_instDir);

launcher/InstanceList.h

@@ -154,6 +154,8 @@ public:
     QStringList mimeTypes() const override;
     QMimeData *mimeData(const QModelIndexList &indexes) const override;
 
+    QStringList getLinkedInstancesById(const QString &id) const;
+
 signals:
     void dataIsInvalid();
     void instancesChanged();

launcher/MMCZip.cpp

@@ -94,20 +94,28 @@ bool MMCZip::mergeZipFiles(QuaZip *into, QFileInfo from, QSet<QString> &containe
     return true;
 }
 
-bool MMCZip::compressDirFiles(QuaZip *zip, QString dir, QFileInfoList files)
+bool MMCZip::compressDirFiles(QuaZip *zip, QString dir, QFileInfoList files, bool followSymlinks)
 {
     QDir directory(dir);
     if (!directory.exists()) return false;
 
     for (auto e : files) {
         auto filePath = directory.relativeFilePath(e.absoluteFilePath());
-        if( !JlCompress::compressFile(zip, e.absoluteFilePath(), filePath)) return false;
+        auto srcPath = e.absoluteFilePath();
+        if (followSymlinks) {
+            if (e.isSymLink()) {
+                srcPath = e.symLinkTarget();
+            } else {
+                srcPath = e.canonicalFilePath();
+            }
+        }
+        if( !JlCompress::compressFile(zip, srcPath, filePath)) return false;
     }
 
     return true;
 }
 
-bool MMCZip::compressDirFiles(QString fileCompressed, QString dir, QFileInfoList files)
+bool MMCZip::compressDirFiles(QString fileCompressed, QString dir, QFileInfoList files, bool followSymlinks)
 {
     QuaZip zip(fileCompressed);
     QDir().mkpath(QFileInfo(fileCompressed).absolutePath());
@@ -116,7 +124,7 @@ bool MMCZip::compressDirFiles(QString fileCompressed, QString dir, QFileInfoList
         return false;
     }
 
-    auto result = compressDirFiles(&zip, dir, files);
+    auto result = compressDirFiles(&zip, dir, files, followSymlinks);
 
     zip.close();
     if(zip.getZipError()!=0) {

launcher/MMCZip.h

@@ -59,18 +59,20 @@ namespace MMCZip
      * \param zip target archive
      * \param dir directory that will be compressed (to compress with relative paths)
      * \param files list of files to compress
+     * \param followSymlinks should follow symlinks when compressing file data
      * \return true for success or false for failure
      */
-    bool compressDirFiles(QuaZip *zip, QString dir, QFileInfoList files);
+    bool compressDirFiles(QuaZip *zip, QString dir, QFileInfoList files, bool followSymlinks = false);
 
     /**
      * Compress directory, by providing a list of files to compress
      * \param fileCompressed target archive file
      * \param dir directory that will be compressed (to compress with relative paths)
      * \param files list of files to compress
+     * \param followSymlinks should follow symlinks when compressing file data
      * \return true for success or false for failure
      */
-    bool compressDirFiles(QString fileCompressed, QString dir, QFileInfoList files);
+    bool compressDirFiles(QString fileCompressed, QString dir, QFileInfoList files, bool followSymlinks = false);
 
     /**
      * take a source jar, add mods to it, resulting in target jar

launcher/QVariantUtils.h

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 Sefa Eyeoglu <contact@scrumplex.net>
+ *  Copyright (C) 2023 flowln <flowlnlnln@gmail.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *
+ *      Copyright 2013-2021 MultiMC Contributors
+ *
+ *      Licensed under the Apache License, Version 2.0 (the "License");
+ *      you may not use this file except in compliance with the License.
+ *      You may obtain a copy of the License at
+ *
+ *          http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *      Unless required by applicable law or agreed to in writing, software
+ *      distributed under the License is distributed on an "AS IS" BASIS,
+ *      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *      See the License for the specific language governing permissions and
+ *      limitations under the License.
+ */
+
+#pragma once
+
+
+#include <QVariant>
+#include <QList>
+
+namespace QVariantUtils {
+
+template <typename T> 
+inline QList<T> toList(QVariant src) {
+    QVariantList variantList = src.toList();
+
+    QList<T> list_t;
+    list_t.reserve(variantList.size());
+    for (const QVariant& v : variantList)
+    {
+        list_t.append(v.value<T>());
+    }
+    return list_t; 
+}
+
+template <typename T> 
+inline QVariant fromList(QList<T> val) {
+    QVariantList variantList;
+    variantList.reserve(val.size());
+    for (const T& v : val)
+    {
+        variantList.append(v);
+    }
+
+    return variantList;
+}
+
+}

launcher/StringUtils.cpp

@@ -1,5 +1,43 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 Sefa Eyeoglu <contact@scrumplex.net>
+ *  Copyright (C) 2023 flowln <flowlnlnln@gmail.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *
+ *      Copyright 2013-2021 MultiMC Contributors
+ *
+ *      Licensed under the Apache License, Version 2.0 (the "License");
+ *      you may not use this file except in compliance with the License.
+ *      You may obtain a copy of the License at
+ *
+ *          http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *      Unless required by applicable law or agreed to in writing, software
+ *      distributed under the License is distributed on an "AS IS" BASIS,
+ *      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *      See the License for the specific language governing permissions and
+ *      limitations under the License.
+ */
+ 
 #include "StringUtils.h"
 
+#include <QUuid>
+
 /// If you're wondering where these came from exactly, then know you're not the only one =D
 
 /// TAKEN FROM Qt, because it doesn't expose it intelligently
@@ -74,3 +112,8 @@ int StringUtils::naturalCompare(const QString& s1, const QString& s2, Qt::CaseSe
     // The two strings are the same (02 == 2) so fall back to the normal sort
     return QString::compare(s1, s2, cs);
 }
+
+QString StringUtils::getRandomAlphaNumeric()
+{
+    return QUuid::createUuid().toString(QUuid::Id128);
+}

launcher/StringUtils.h

@@ -1,3 +1,39 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 Sefa Eyeoglu <contact@scrumplex.net>
+ *  Copyright (C) 2023 flowln <flowlnlnln@gmail.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *
+ *      Copyright 2013-2021 MultiMC Contributors
+ *
+ *      Licensed under the Apache License, Version 2.0 (the "License");
+ *      you may not use this file except in compliance with the License.
+ *      You may obtain a copy of the License at
+ *
+ *          http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *      Unless required by applicable law or agreed to in writing, software
+ *      distributed under the License is distributed on an "AS IS" BASIS,
+ *      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *      See the License for the specific language governing permissions and
+ *      limitations under the License.
+ */
+
 #pragma once
 
 #include <QString>
@@ -29,4 +65,6 @@ inline QString fromStdString(string s)
 #endif
 
 int naturalCompare(const QString& s1, const QString& s2, Qt::CaseSensitivity cs);
+
+QString getRandomAlphaNumeric();
 }  // namespace StringUtils

launcher/filelink/FileLink.cpp

@@ -0,0 +1,277 @@
+// SPDX-FileCopyrightText: 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
+//
+// SPDX-License-Identifier: GPL-3.0-only
+
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "FileLink.h"
+#include "BuildConfig.h"
+
+#include "StringUtils.h"
+
+#include <iostream>
+
+#include <QAccessible>
+#include <QCommandLineParser>
+
+#include <QDebug>
+
+#include <DesktopServices.h>
+
+#include <sys.h>
+
+#if defined Q_OS_WIN32
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include <stdio.h>
+#include <windows.h>
+#endif
+
+// Snippet from https://github.com/gulrak/filesystem#using-it-as-single-file-header
+
+#ifdef __APPLE__
+#include <Availability.h>  // for deployment target to support pre-catalina targets without std::fs
+#endif                     // __APPLE__
+
+#if ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703L) || (defined(__cplusplus) && __cplusplus >= 201703L)) && defined(__has_include)
+#if __has_include(<filesystem>) && (!defined(__MAC_OS_X_VERSION_MIN_REQUIRED) || __MAC_OS_X_VERSION_MIN_REQUIRED >= 101500)
+#define GHC_USE_STD_FS
+#include <filesystem>
+namespace fs = std::filesystem;
+#endif  // MacOS min version check
+#endif  // Other OSes version check
+
+#ifndef GHC_USE_STD_FS
+#include <ghc/filesystem.hpp>
+namespace fs = ghc::filesystem;
+#endif
+
+FileLinkApp::FileLinkApp(int& argc, char** argv) : QCoreApplication(argc, argv), socket(new QLocalSocket(this))
+{
+#if defined Q_OS_WIN32
+    // attach the parent console
+    if (AttachConsole(ATTACH_PARENT_PROCESS)) {
+        // if attach succeeds, reopen and sync all the i/o
+        if (freopen("CON", "w", stdout)) {
+            std::cout.sync_with_stdio();
+        }
+        if (freopen("CON", "w", stderr)) {
+            std::cerr.sync_with_stdio();
+        }
+        if (freopen("CON", "r", stdin)) {
+            std::cin.sync_with_stdio();
+        }
+        auto out = GetStdHandle(STD_OUTPUT_HANDLE);
+        DWORD written;
+        const char* endline = "\n";
+        WriteConsole(out, endline, strlen(endline), &written, NULL);
+        consoleAttached = true;
+    }
+#endif
+    setOrganizationName(BuildConfig.LAUNCHER_NAME);
+    setOrganizationDomain(BuildConfig.LAUNCHER_DOMAIN);
+    setApplicationName(BuildConfig.LAUNCHER_NAME + "FileLink");
+    setApplicationVersion(BuildConfig.printableVersionString() + "\n" + BuildConfig.GIT_COMMIT);
+
+    // Commandline parsing
+    QCommandLineParser parser;
+    parser.setApplicationDescription(QObject::tr("a batch MKLINK program for windows to be used with prismlauncher"));
+
+    parser.addOptions({ { { "s", "server" }, "Join the specified server on launch", "pipe name" },
+                        { { "H", "hard" }, "use hard links instead of symbolic", "true/false" } });
+    parser.addHelpOption();
+    parser.addVersionOption();
+
+    parser.process(arguments());
+
+    QString serverToJoin = parser.value("server");
+    m_useHardLinks = QVariant(parser.value("hard")).toBool();
+
+    qDebug() << "link program launched";
+
+    if (!serverToJoin.isEmpty()) {
+        qDebug() << "joining server" << serverToJoin;
+        joinServer(serverToJoin);
+    } else {
+        qDebug() << "no server to join";
+        exit();
+    }
+}
+
+void FileLinkApp::joinServer(QString server)
+{
+    blockSize = 0;
+
+    in.setDevice(&socket);
+
+    connect(&socket, &QLocalSocket::connected, this, [&]() { qDebug() << "connected to server"; });
+
+    connect(&socket, &QLocalSocket::readyRead, this, &FileLinkApp::readPathPairs);
+
+    connect(&socket, &QLocalSocket::errorOccurred, this, [&](QLocalSocket::LocalSocketError socketError) {
+        switch (socketError) {
+            case QLocalSocket::ServerNotFoundError:
+                qDebug()
+                    << ("The host was not found. Please make sure "
+                        "that the server is running and that the "
+                        "server name is correct.");
+                break;
+            case QLocalSocket::ConnectionRefusedError:
+                qDebug()
+                    << ("The connection was refused by the peer. "
+                        "Make sure the server is running, "
+                        "and check that the server name "
+                        "is correct.");
+                break;
+            case QLocalSocket::PeerClosedError:
+                qDebug() << ("The connection was closed by the peer. ");
+                break;
+            default:
+                qDebug() << "The following error occurred: " << socket.errorString();
+        }
+    });
+
+    connect(&socket, &QLocalSocket::disconnected, this, [&]() {
+        qDebug() << "disconnected from server, should exit";
+        exit();
+    });
+
+    socket.connectToServer(server);
+}
+
+void FileLinkApp::runLink()
+{
+    std::error_code os_err;
+
+    qDebug() << "creating links";
+
+    for (auto link : m_links_to_make) {
+        QString src_path = link.src;
+        QString dst_path = link.dst;
+
+        FS::ensureFilePathExists(dst_path);
+        if (m_useHardLinks) {
+            qDebug() << "making hard link:" << src_path << "to" << dst_path;
+            fs::create_hard_link(StringUtils::toStdString(src_path), StringUtils::toStdString(dst_path), os_err);
+        } else if (fs::is_directory(StringUtils::toStdString(src_path))) {
+            qDebug() << "making directory_symlink:" << src_path << "to" << dst_path;
+            fs::create_directory_symlink(StringUtils::toStdString(src_path), StringUtils::toStdString(dst_path), os_err);
+        } else {
+            qDebug() << "making symlink:" << src_path << "to" << dst_path;
+            fs::create_symlink(StringUtils::toStdString(src_path), StringUtils::toStdString(dst_path), os_err);
+        }
+
+        if (os_err) {
+            qWarning() << "Failed to link files:" << QString::fromStdString(os_err.message());
+            qDebug() << "Source file:" << src_path;
+            qDebug() << "Destination file:" << dst_path;
+            qDebug() << "Error category:" << os_err.category().name();
+            qDebug() << "Error code:" << os_err.value();
+
+            FS::LinkResult result = { src_path, dst_path, QString::fromStdString(os_err.message()), os_err.value() };
+            m_path_results.append(result);
+        } else {
+            FS::LinkResult result = { src_path, dst_path };
+            m_path_results.append(result);
+        }
+    }
+
+    sendResults();
+    qDebug() << "done, should exit soon";
+}
+
+void FileLinkApp::sendResults()
+{
+    // construct block of data to send
+    QByteArray block;
+    QDataStream out(&block, QIODevice::WriteOnly);
+
+    qint32 blocksize = quint32(sizeof(quint32));
+    for (auto result : m_path_results) {
+        blocksize += quint32(result.src.size());
+        blocksize += quint32(result.dst.size());
+        blocksize += quint32(result.err_msg.size());
+        blocksize += quint32(sizeof(quint32));
+    }
+    qDebug() << "About to write block of size:" << blocksize;
+    out << blocksize;
+
+    out << quint32(m_path_results.length());
+    for (auto result : m_path_results) {
+        out << result.src;
+        out << result.dst;
+        out << result.err_msg;
+        out << quint32(result.err_value);
+    }
+
+    qint64 byteswritten = socket.write(block);
+    bool bytesflushed = socket.flush();
+    qDebug() << "block flushed" << byteswritten << bytesflushed;
+}
+
+void FileLinkApp::readPathPairs()
+{
+    m_links_to_make.clear();
+    qDebug() << "Reading path pairs from server";
+    qDebug() << "bytes available" << socket.bytesAvailable();
+    if (blockSize == 0) {
+        // Relies on the fact that QDataStream serializes a quint32 into
+        // sizeof(quint32) bytes
+        if (socket.bytesAvailable() < (int)sizeof(quint32))
+            return;
+        qDebug() << "reading block size";
+        in >> blockSize;
+    }
+    qDebug() << "blocksize is" << blockSize;
+    qDebug() << "bytes available" << socket.bytesAvailable();
+    if (socket.bytesAvailable() < blockSize || in.atEnd())
+        return;
+
+    quint32 numLinks;
+    in >> numLinks;
+    qDebug() << "numLinks" << numLinks;
+
+    for (int i = 0; i < numLinks; i++) {
+        FS::LinkPair pair;
+        in >> pair.src;
+        in >> pair.dst;
+        qDebug() << "link" << pair.src << "to" << pair.dst;
+        m_links_to_make.append(pair);
+    }
+
+    runLink();
+}
+
+FileLinkApp::~FileLinkApp()
+{
+    qDebug() << "link program shutting down";
+    // Shut down logger by setting the logger function to nothing
+    qInstallMessageHandler(nullptr);
+
+#if defined Q_OS_WIN32
+    // Detach from Windows console
+    if (consoleAttached) {
+        fclose(stdout);
+        fclose(stdin);
+        fclose(stderr);
+        FreeConsole();
+    }
+#endif
+}

launcher/filelink/FileLink.h

@@ -0,0 +1,67 @@
+// SPDX-FileCopyrightText: 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
+//
+// SPDX-License-Identifier: GPL-3.0-only
+
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <QtCore>
+
+#include <QApplication>
+#include <QDataStream>
+#include <QDateTime>
+#include <QDebug>
+#include <QFlag>
+#include <QIcon>
+#include <QLocalSocket>
+#include <QUrl>
+#include <memory>
+
+#define PRISM_EXTERNAL_EXE
+#include "FileSystem.h"
+
+class FileLinkApp : public QCoreApplication {
+    // friends for the purpose of limiting access to deprecated stuff
+    Q_OBJECT
+   public:
+    FileLinkApp(int& argc, char** argv);
+    virtual ~FileLinkApp();
+
+   private:
+    void joinServer(QString server);
+    void readPathPairs();
+    void runLink();
+    void sendResults();
+
+    bool m_useHardLinks = false;
+
+    QDateTime m_startTime;
+    QLocalSocket socket;
+    QDataStream in;
+    quint32 blockSize;
+
+    QList<FS::LinkPair> m_links_to_make;
+    QList<FS::LinkResult> m_path_results;
+
+#if defined Q_OS_WIN32
+    // used on Windows to attach the standard IO streams
+    bool consoleAttached = false;
+#endif
+};

launcher/filelink/filelink.exe.manifest

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
+  <application xmlns="urn:schemas-microsoft-com:asm.v3">
+    <windowsSettings>
+    </windowsSettings>
+  </application>
+  <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
+    <application>
+      <!-- Windows 10, Windows 11 -->
+      <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}"/>
+      <!-- Windows 8.1 -->
+      <supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}"/>
+      <!-- Windows 8 -->
+      <supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}"/>
+      <!-- Windows 7 -->
+      <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/>
+    </application>
+  </compatibility>
+  <trustInfo xmlns="urn:schemas-microsoft-com:asm.v2">
+    <security>
+      <requestedPrivileges>
+        <requestedExecutionLevel
+          level="requireAdministrator"
+          uiAccess="false"/>
+       </requestedPrivileges>
+    </security>
+  </trustInfo>
+</assembly>

launcher/filelink/main.cpp

@@ -0,0 +1,30 @@
+// SPDX-FileCopyrightText: 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
+//
+// SPDX-License-Identifier: GPL-3.0-only
+
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 Rachel Powers <508861+Ryex@users.noreply.github.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "FileLink.h"
+
+int main(int argc, char* argv[])
+{
+    FileLinkApp ldh(argc, argv);
+
+    return ldh.exec();
+}

launcher/minecraft/MinecraftInstance.cpp

@@ -1114,7 +1114,7 @@ std::shared_ptr<ModFolderModel> MinecraftInstance::loaderModList() const
     if (!m_loader_mod_list)
     {
         bool is_indexed = !APPLICATION->settings()->get("ModMetadataDisabled").toBool();
-        m_loader_mod_list.reset(new ModFolderModel(modsRoot(), is_indexed));
+        m_loader_mod_list.reset(new ModFolderModel(modsRoot(), shared_from_this(), is_indexed));
         m_loader_mod_list->disableInteraction(isRunning());
         connect(this, &BaseInstance::runningStatusChanged, m_loader_mod_list.get(), &ModFolderModel::disableInteraction);
     }
@@ -1126,7 +1126,7 @@ std::shared_ptr<ModFolderModel> MinecraftInstance::coreModList() const
     if (!m_core_mod_list)
     {
         bool is_indexed = !APPLICATION->settings()->get("ModMetadataDisabled").toBool();
-        m_core_mod_list.reset(new ModFolderModel(coreModsDir(), is_indexed));
+        m_core_mod_list.reset(new ModFolderModel(coreModsDir(), shared_from_this(), is_indexed));
         m_core_mod_list->disableInteraction(isRunning());
         connect(this, &BaseInstance::runningStatusChanged, m_core_mod_list.get(), &ModFolderModel::disableInteraction);
     }
@@ -1138,7 +1138,7 @@ std::shared_ptr<ModFolderModel> MinecraftInstance::nilModList() const
     if (!m_nil_mod_list)
     {
         bool is_indexed = !APPLICATION->settings()->get("ModMetadataDisabled").toBool();
-        m_nil_mod_list.reset(new ModFolderModel(nilModsDir(), is_indexed, false));
+        m_nil_mod_list.reset(new ModFolderModel(nilModsDir(), shared_from_this(), is_indexed, false));
         m_nil_mod_list->disableInteraction(isRunning());
         connect(this, &BaseInstance::runningStatusChanged, m_nil_mod_list.get(), &ModFolderModel::disableInteraction);
     }
@@ -1149,7 +1149,7 @@ std::shared_ptr<ResourcePackFolderModel> MinecraftInstance::resourcePackList() c
 {
     if (!m_resource_pack_list)
     {
-        m_resource_pack_list.reset(new ResourcePackFolderModel(resourcePacksDir()));
+        m_resource_pack_list.reset(new ResourcePackFolderModel(resourcePacksDir(), shared_from_this()));
     }
     return m_resource_pack_list;
 }
@@ -1158,7 +1158,7 @@ std::shared_ptr<TexturePackFolderModel> MinecraftInstance::texturePackList() con
 {
     if (!m_texture_pack_list)
     {
-        m_texture_pack_list.reset(new TexturePackFolderModel(texturePacksDir()));
+        m_texture_pack_list.reset(new TexturePackFolderModel(texturePacksDir(), shared_from_this()));
     }
     return m_texture_pack_list;
 }
@@ -1167,7 +1167,7 @@ std::shared_ptr<ShaderPackFolderModel> MinecraftInstance::shaderPackList() const
 {
     if (!m_shader_pack_list)
     {
-        m_shader_pack_list.reset(new ShaderPackFolderModel(shaderPacksDir()));
+        m_shader_pack_list.reset(new ShaderPackFolderModel(shaderPacksDir(), shared_from_this()));
     }
     return m_shader_pack_list;
 }
@@ -1176,7 +1176,7 @@ std::shared_ptr<WorldList> MinecraftInstance::worldList() const
 {
     if (!m_world_list)
     {
-        m_world_list.reset(new WorldList(worldDir()));
+        m_world_list.reset(new WorldList(worldDir(), shared_from_this()));
     }
     return m_world_list;
 }

launcher/minecraft/World.cpp

@@ -56,6 +56,8 @@
 
 #include <optional>
 
+#include "FileSystem.h"
+
 using std::optional;
 using std::nullopt;
 
@@ -567,3 +569,25 @@ bool World::operator==(const World &other) const
 {
     return is_valid == other.is_valid && folderName() == other.folderName();
 }
+
+bool World::isSymLinkUnder(const QString& instPath) const
+{
+    if (isSymLink())
+        return true;
+
+    auto instDir = QDir(instPath);
+
+    auto relAbsPath = instDir.relativeFilePath(m_containerFile.absoluteFilePath());
+    auto relCanonPath = instDir.relativeFilePath(m_containerFile.canonicalFilePath());
+
+    return relAbsPath != relCanonPath;
+}
+
+bool World::isMoreThanOneHardLink() const
+{
+    if (m_containerFile.isDir())
+    {
+        return FS::hardLinkCount(QDir(m_containerFile.absoluteFilePath()).filePath("level.dat")) > 1;
+    }
+    return FS::hardLinkCount(m_containerFile.absoluteFilePath()) > 1;
+}

launcher/minecraft/World.h

@@ -95,6 +95,21 @@ public:
     // WEAK compare operator - used for replacing worlds
     bool operator==(const World &other) const;
 
+    [[nodiscard]] auto isSymLink() const -> bool{ return m_containerFile.isSymLink(); }
+
+    /**
+     * @brief Take a instance path, checks if the file pointed to by the resource is a symlink or under a symlink in that instance
+     * 
+     * @param instPath path to an instance directory
+     * @return true 
+     * @return false 
+     */
+    [[nodiscard]] bool isSymLinkUnder(const QString& instPath) const;
+
+    [[nodiscard]] bool isMoreThanOneHardLink() const;
+
+    QString canonicalFilePath() const { return m_containerFile.canonicalFilePath(); }
+
 private:
     void readFromZip(const QFileInfo &file);
     void readFromFS(const QFileInfo &file);

launcher/minecraft/WorldList.cpp

@@ -45,8 +45,8 @@
 #include <QFileSystemWatcher>
 #include <QDebug>
 
-WorldList::WorldList(const QString &dir)
+WorldList::WorldList(const QString &dir, std::shared_ptr<const BaseInstance> instance)
-    : QAbstractListModel(), m_dir(dir)
+    : QAbstractListModel(), m_instance(instance), m_dir(dir)
 {
     FS::ensureFolderPathExists(m_dir.absolutePath());
     m_dir.setFilter(QDir::Readable | QDir::NoDotAndDotDot | QDir::Files | QDir::Dirs);
@@ -128,6 +128,10 @@ bool WorldList::isValid()
     return m_dir.exists() && m_dir.isReadable();
 }
 
+QString WorldList::instDirPath() const {
+    return QFileInfo(m_instance->instanceRoot()).absoluteFilePath();
+}
+
 bool WorldList::deleteWorld(int index)
 {
     if (index >= worlds.size() || index < 0)
@@ -173,7 +177,7 @@ bool WorldList::resetIcon(int row)
 
 int WorldList::columnCount(const QModelIndex &parent) const
 {
-    return parent.isValid()? 0 : 4;
+    return parent.isValid()? 0 : 5;
 }
 
 QVariant WorldList::data(const QModelIndex &index, int role) const
@@ -207,6 +211,14 @@ QVariant WorldList::data(const QModelIndex &index, int role) const
         case SizeColumn:
             return locale.formattedDataSize(world.bytes());
 
+        case InfoColumn:
+            if (world.isSymLinkUnder(instDirPath())) {
+                return tr("This world is symbolically linked from elsewhere.");
+            }
+            if (world.isMoreThanOneHardLink()) {
+                return tr("\nThis world is hard linked elsewhere.");
+            }
+            return "";
         default:
             return QVariant();
         }
@@ -223,6 +235,15 @@ QVariant WorldList::data(const QModelIndex &index, int role) const
 
     case Qt::ToolTipRole:
     {   
+        if (column == InfoColumn) {
+            if (world.isSymLinkUnder(instDirPath())) {
+                return tr("Warning: This world is symbolically linked from elsewhere. Editing it will also change the original." 
+                          "\nCanonical Path: %1").arg(world.canonicalFilePath());
+            }
+            if (world.isMoreThanOneHardLink()) {
+                return tr("Warning: This world is hard linked elsewhere. Editing it will also change the original.");
+            }
+        }
         return world.folderName();
     }
     case ObjectRole:
@@ -274,6 +295,9 @@ QVariant WorldList::headerData(int section, Qt::Orientation orientation, int rol
         case SizeColumn:
             //: World size on disk
             return tr("Size");
+        case InfoColumn:
+            //: special warnings?
+            return tr("Info");
         default:
             return QVariant();
         }
@@ -289,6 +313,8 @@ QVariant WorldList::headerData(int section, Qt::Orientation orientation, int rol
             return tr("Date and time the world was last played.");
         case SizeColumn:
             return tr("Size of the world on disk.");
+        case InfoColumn:
+            return tr("Information and warnings about the world.");
         default:
             return QVariant();
         }

launcher/minecraft/WorldList.h

@@ -21,6 +21,7 @@
 #include <QAbstractListModel>
 #include <QMimeData>
 #include "minecraft/World.h"
+#include "BaseInstance.h"
 
 class QFileSystemWatcher;
 
@@ -33,7 +34,8 @@ public:
         NameColumn,
         GameModeColumn,
         LastPlayedColumn,
-        SizeColumn
+        SizeColumn,
+        InfoColumn
     };
 
     enum Roles
@@ -48,7 +50,7 @@ public:
         IconFileRole
     };
 
-    WorldList(const QString &dir);
+    WorldList(const QString &dir, std::shared_ptr<const BaseInstance> instance);
 
     virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
 
@@ -112,6 +114,8 @@ public:
         return m_dir;
     }
 
+    QString instDirPath() const;
+
     const QList<World> &allWorlds() const
     {
         return worlds;
@@ -124,6 +128,7 @@ signals:
     void changed();
 
 protected:
+    std::shared_ptr<const BaseInstance> m_instance;
     QFileSystemWatcher *m_watcher;
     bool is_watching;
     QDir m_dir;

launcher/minecraft/mod/ModFolderModel.cpp

@@ -39,18 +39,23 @@
 #include <FileSystem.h>
 #include <QDebug>
 #include <QFileSystemWatcher>
+#include <QIcon>
 #include <QMimeData>
 #include <QString>
+#include <QStyle>
 #include <QThreadPool>
 #include <QUrl>
 #include <QUuid>
 #include <algorithm>
 
+#include "Application.h"
+
 #include "minecraft/mod/tasks/LocalModParseTask.h"
 #include "minecraft/mod/tasks/ModFolderLoadTask.h"
 #include "modplatform/ModIndex.h"
 
-ModFolderModel::ModFolderModel(const QString &dir, bool is_indexed, bool create_dir) : ResourceFolderModel(QDir(dir), nullptr, create_dir), m_is_indexed(is_indexed)
+ModFolderModel::ModFolderModel(const QString& dir, std::shared_ptr<const BaseInstance> instance, bool is_indexed, bool create_dir)
+    : ResourceFolderModel(QDir(dir), instance, nullptr, create_dir), m_is_indexed(is_indexed)
 {
     m_column_sort_keys = { SortType::ENABLED, SortType::NAME, SortType::VERSION, SortType::DATE, SortType::PROVIDER };
 }
@@ -97,8 +102,25 @@ QVariant ModFolderModel::data(const QModelIndex &index, int role) const
         }
 
     case Qt::ToolTipRole:
+        if (column == NAME_COLUMN) {
+            if (at(row)->isSymLinkUnder(instDirPath())) {
+                return m_resources[row]->internal_id() +
+                    tr("\nWarning: This resource is symbolically linked from elsewhere. Editing it will also change the original." 
+                       "\nCanonical Path: %1")
+                        .arg(at(row)->fileinfo().canonicalFilePath());
+            }
+            if (at(row)->isMoreThanOneHardLink()) {
+                return m_resources[row]->internal_id() +
+                    tr("\nWarning: This resource is hard linked elsewhere. Editing it will also change the original.");
+            }
+        }
         return m_resources[row]->internal_id();
+    case Qt::DecorationRole: {
+        if (column == NAME_COLUMN && (at(row)->isSymLinkUnder(instDirPath()) || at(row)->isMoreThanOneHardLink()))
+            return APPLICATION->getThemedIcon("status-yellow");
 
+        return {};
+    }
     case Qt::CheckStateRole:
         switch (column)
         {

launcher/minecraft/mod/ModFolderModel.h

@@ -75,7 +75,7 @@ public:
         Enable,
         Toggle
     };
-    ModFolderModel(const QString &dir, bool is_indexed = false, bool create_dir = true);
+    ModFolderModel(const QString &dir, std::shared_ptr<const BaseInstance> instance, bool is_indexed = false, bool create_dir = true);
 
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
 

launcher/minecraft/mod/Resource.cpp

@@ -1,6 +1,8 @@
 #include "Resource.h"
 
+
 #include <QRegularExpression>
+#include <QFileInfo>
 
 #include "FileSystem.h"
 
@@ -152,3 +154,21 @@ bool Resource::destroy()
 
     return FS::deletePath(m_file_info.filePath());
 }
+
+bool Resource::isSymLinkUnder(const QString& instPath) const 
+{
+    if (isSymLink())
+        return true;
+
+    auto instDir = QDir(instPath);
+
+    auto relAbsPath = instDir.relativeFilePath(m_file_info.absoluteFilePath());
+    auto relCanonPath = instDir.relativeFilePath(m_file_info.canonicalFilePath());
+
+    return relAbsPath != relCanonPath;
+}
+
+bool Resource::isMoreThanOneHardLink() const 
+{
+    return FS::hardLinkCount(m_file_info.absoluteFilePath()) > 1;
+}

launcher/minecraft/mod/Resource.h

@@ -94,6 +94,19 @@ class Resource : public QObject {
     // Delete all files of this resource.
     bool destroy();
 
+    [[nodiscard]] auto isSymLink() const -> bool { return m_file_info.isSymLink(); }
+
+    /**
+     * @brief Take a instance path, checks if the file pointed to by the resource is a symlink or under a symlink in that instance
+     * 
+     * @param instPath path to an instance directory
+     * @return true 
+     * @return false 
+     */
+    [[nodiscard]] bool isSymLinkUnder(const QString& instPath) const;
+
+    [[nodiscard]] bool isMoreThanOneHardLink() const;
+
    protected:
     /* The file corresponding to this resource. */
     QFileInfo m_file_info;

launcher/minecraft/mod/ResourceFolderModel.cpp

@@ -2,17 +2,22 @@
 
 #include <QCoreApplication>
 #include <QDebug>
+#include <QFileInfo>
+#include <QIcon>
 #include <QMimeData>
+#include <QStyle>
 #include <QThreadPool>
 #include <QUrl>
 
+#include "Application.h"
 #include "FileSystem.h"
 
 #include "minecraft/mod/tasks/BasicFolderLoadTask.h"
 
 #include "tasks/Task.h"
 
-ResourceFolderModel::ResourceFolderModel(QDir dir, QObject* parent, bool create_dir) : QAbstractListModel(parent), m_dir(dir), m_watcher(this)
+ResourceFolderModel::ResourceFolderModel(QDir dir, std::shared_ptr<const BaseInstance> instance, QObject* parent, bool create_dir)
+    : QAbstractListModel(parent), m_dir(dir), m_instance(instance), m_watcher(this)
 {
     if (create_dir) {
         FS::ensureFolderPathExists(m_dir.absolutePath());
@@ -22,7 +27,7 @@ ResourceFolderModel::ResourceFolderModel(QDir dir, QObject* parent, bool create_
     m_dir.setSorting(QDir::Name | QDir::IgnoreCase | QDir::LocaleAware);
 
     connect(&m_watcher, &QFileSystemWatcher::directoryChanged, this, &ResourceFolderModel::directoryChanged);
-    connect(&m_helper_thread_task, &ConcurrentTask::finished, this, [this]{ m_helper_thread_task.clear(); });
+    connect(&m_helper_thread_task, &ConcurrentTask::finished, this, [this] { m_helper_thread_task.clear(); });
 }
 
 ResourceFolderModel::~ResourceFolderModel()
@@ -417,7 +422,26 @@ QVariant ResourceFolderModel::data(const QModelIndex& index, int role) const
                     return {};
             }
         case Qt::ToolTipRole:
+            if (column == NAME_COLUMN) {
+                if (at(row).isSymLinkUnder(instDirPath())) {
+                    return m_resources[row]->internal_id() +
+                        tr("\nWarning: This resource is symbolically linked from elsewhere. Editing it will also change the original."
+                           "\nCanonical Path: %1")
+                            .arg(at(row).fileinfo().canonicalFilePath());;
+                }
+                if (at(row).isMoreThanOneHardLink()) {
+                    return m_resources[row]->internal_id() +
+                        tr("\nWarning: This resource is hard linked elsewhere. Editing it will also change the original.");
+                }
+            }
+            
             return m_resources[row]->internal_id();
+        case Qt::DecorationRole: {
+            if (column == NAME_COLUMN && (at(row).isSymLinkUnder(instDirPath()) || at(row).isMoreThanOneHardLink()))
+                return APPLICATION->getThemedIcon("status-yellow");
+
+            return {};
+        }
         case Qt::CheckStateRole:
             switch (column) {
                 case ACTIVE_COLUMN:
@@ -531,3 +555,7 @@ void ResourceFolderModel::enableInteraction(bool enabled)
         return (compare_result.first < 0);
     return (compare_result.first > 0);
 }
+
+QString ResourceFolderModel::instDirPath() const {
+    return QFileInfo(m_instance->instanceRoot()).absoluteFilePath();
+}

launcher/minecraft/mod/ResourceFolderModel.h

@@ -9,6 +9,8 @@
 
 #include "Resource.h"
 
+#include "BaseInstance.h"
+
 #include "tasks/Task.h"
 #include "tasks/ConcurrentTask.h"
 
@@ -24,7 +26,7 @@ class QSortFilterProxyModel;
 class ResourceFolderModel : public QAbstractListModel {
     Q_OBJECT
    public:
-    ResourceFolderModel(QDir, QObject* parent = nullptr, bool create_dir = true);
+    ResourceFolderModel(QDir, std::shared_ptr<const BaseInstance>, QObject* parent = nullptr, bool create_dir = true);
     ~ResourceFolderModel() override;
 
     /** Starts watching the paths for changes.
@@ -125,6 +127,8 @@ class ResourceFolderModel : public QAbstractListModel {
         [[nodiscard]] bool lessThan(const QModelIndex& source_left, const QModelIndex& source_right) const override;
     };
 
+    QString instDirPath() const;
+
    public slots:
     void enableInteraction(bool enabled);
     void disableInteraction(bool disabled) { enableInteraction(!disabled); }
@@ -187,6 +191,7 @@ class ResourceFolderModel : public QAbstractListModel {
     bool m_can_interact = true;
 
     QDir m_dir;
+    std::shared_ptr<const BaseInstance> m_instance;
     QFileSystemWatcher m_watcher;
     bool m_is_watching = false;
 

launcher/minecraft/mod/ResourcePackFolderModel.cpp

@@ -36,12 +36,17 @@
 
 #include "ResourcePackFolderModel.h"
 
+#include <QIcon>
+#include <QStyle>
+
+#include "Application.h"
 #include "Version.h"
 
 #include "minecraft/mod/tasks/BasicFolderLoadTask.h"
 #include "minecraft/mod/tasks/LocalResourcePackParseTask.h"
 
-ResourcePackFolderModel::ResourcePackFolderModel(const QString& dir) : ResourceFolderModel(QDir(dir))
+ResourcePackFolderModel::ResourcePackFolderModel(const QString& dir, std::shared_ptr<const BaseInstance> instance)
+    : ResourceFolderModel(QDir(dir), instance)
 {
     m_column_sort_keys = { SortType::ENABLED, SortType::NAME, SortType::PACK_FORMAT, SortType::DATE };
 }
@@ -78,12 +83,29 @@ QVariant ResourcePackFolderModel::data(const QModelIndex& index, int role) const
                 default:
                     return {};
             }
+        case Qt::DecorationRole: {
+            if (column == NAME_COLUMN && (at(row)->isSymLinkUnder(instDirPath()) || at(row)->isMoreThanOneHardLink()))
+                return APPLICATION->getThemedIcon("status-yellow");
 
+            return {};
+        }
         case Qt::ToolTipRole: {
             if (column == PackFormatColumn) {
                 //: The string being explained by this is in the format: ID (Lower version - Upper version)
                 return tr("The resource pack format ID, as well as the Minecraft versions it was designed for.");
             }
+            if (column == NAME_COLUMN) {
+                if (at(row)->isSymLinkUnder(instDirPath())) {
+                    return m_resources[row]->internal_id() +
+                        tr("\nWarning: This resource is symbolically linked from elsewhere. Editing it will also change the original."
+                           "\nCanonical Path: %1")
+                            .arg(at(row)->fileinfo().canonicalFilePath());;
+                }
+                if (at(row)->isMoreThanOneHardLink()) {
+                    return m_resources[row]->internal_id() +
+                        tr("\nWarning: This resource is hard linked elsewhere. Editing it will also change the original.");
+                }
+            }
             return m_resources[row]->internal_id();
         }
         case Qt::CheckStateRole:

launcher/minecraft/mod/ResourcePackFolderModel.h

@@ -17,7 +17,7 @@ public:
         NUM_COLUMNS
     };
 
-    explicit ResourcePackFolderModel(const QString &dir);
+    explicit ResourcePackFolderModel(const QString &dir, std::shared_ptr<const BaseInstance> instance);
 
     [[nodiscard]] QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
 

launcher/minecraft/mod/ShaderPackFolderModel.h

@@ -6,5 +6,7 @@ class ShaderPackFolderModel : public ResourceFolderModel {
     Q_OBJECT
 
    public:
-    explicit ShaderPackFolderModel(const QString& dir) : ResourceFolderModel(QDir(dir)) {}
+    explicit ShaderPackFolderModel(const QString& dir, std::shared_ptr<const BaseInstance> instance)
+        : ResourceFolderModel(QDir(dir), instance)
+    {}
 };

launcher/minecraft/mod/TexturePackFolderModel.cpp

@@ -39,7 +39,9 @@
 #include "minecraft/mod/tasks/BasicFolderLoadTask.h"
 #include "minecraft/mod/tasks/LocalTexturePackParseTask.h"
 
-TexturePackFolderModel::TexturePackFolderModel(const QString &dir) : ResourceFolderModel(QDir(dir)) {}
+TexturePackFolderModel::TexturePackFolderModel(const QString& dir, std::shared_ptr<const BaseInstance> instance)
+    : ResourceFolderModel(QDir(dir), instance)
+{}
 
 Task* TexturePackFolderModel::createUpdateTask()
 {

launcher/minecraft/mod/TexturePackFolderModel.h

@@ -43,7 +43,7 @@ class TexturePackFolderModel : public ResourceFolderModel
     Q_OBJECT
 
 public:
-    explicit TexturePackFolderModel(const QString &dir);
+    explicit TexturePackFolderModel(const QString &dir, std::shared_ptr<const BaseInstance> instance);
     [[nodiscard]] Task* createUpdateTask() override;
     [[nodiscard]] Task* createParseTask(Resource&) override;
 };

launcher/minecraft/mod/tasks/LocalModParseTask.cpp

@@ -242,7 +242,7 @@ ModDetails ReadQuiltModInfo(QByteArray contents)
     return details;
 }
 
-ModDetails ReadForgeInfo(QByteArray contents)
+ModDetails ReadForgeInfo(QString fileName)
 {
     ModDetails details;
     // Read the data
@@ -250,7 +250,7 @@ ModDetails ReadForgeInfo(QByteArray contents)
     details.mod_id = "Forge";
     details.homeurl = "http://www.minecraftforge.net/forum/";
     INIFile ini;
-    if (!ini.loadFile(contents))
+    if (!ini.loadFile(fileName))
         return details;
 
     QString major = ini.get("forge.major.number", "0").toString();
@@ -422,7 +422,7 @@ bool processZIP(Mod& mod, ProcessingLevel level)
             return false;
         }
 
-        details = ReadForgeInfo(file.readAll());
+        details = ReadForgeInfo(file.getFileName());
         file.close();
         zip.close();
 

launcher/settings/INIFile.cpp

@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: GPL-3.0-only
 /*
- *  PolyMC - Minecraft Launcher
+ *  Prism Launcher - Minecraft Launcher
  *  Copyright (C) 2022 Sefa Eyeoglu <contact@scrumplex.net>
+ *  Copyright (C) 2023 flowln <flowlnlnln@gmail.com>
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -42,131 +43,50 @@
 #include <QSaveFile>
 #include <QDebug>
 
+#include <QSettings>
+
 INIFile::INIFile()
 {
 }
 
-QString INIFile::unescape(QString orig)
-{
-    QString out;
-    QChar prev = QChar::Null;
-    for(auto c: orig)
-    {
-        if(prev == '\\')
-        {
-            if(c == 'n')
-                out += '\n';
-            else if(c == 't')
-                out += '\t';
-            else if(c == '#')
-                out += '#';
-            else
-                out += c;
-            prev = QChar::Null;
-        }
-        else
-        {
-            if(c == '\\')
-            {
-                prev = c;
-                continue;
-            }
-            out += c;
-            prev = QChar::Null;
-        }
-    }
-    return out;
-}
-
-QString INIFile::escape(QString orig)
-{
-    QString out;
-    for(auto c: orig)
-    {
-        if(c == '\n')
-            out += "\\n";
-        else if (c == '\t')
-            out += "\\t";
-        else if(c == '\\')
-            out += "\\\\";
-        else if(c == '#')
-            out += "\\#";
-        else
-            out += c;
-    }
-    return out;
-}
-
 bool INIFile::saveFile(QString fileName)
 {
-    QByteArray outArray;
+    QSettings _settings_obj{ fileName, QSettings::Format::IniFormat };
-    for (Iterator iter = begin(); iter != end(); iter++)
+    _settings_obj.setFallbacksEnabled(false);
-    {
+
-        QString value = iter.value().toString();
+    for (Iterator iter = begin(); iter != end(); iter++)
-        value = escape(value);
+        _settings_obj.setValue(iter.key(), iter.value());
-        outArray.append(iter.key().toUtf8());
+
-        outArray.append('=');
+    _settings_obj.sync();
-        outArray.append(value.toUtf8());
+
-        outArray.append('\n');
+    if (auto status = _settings_obj.status(); status != QSettings::Status::NoError) {
-    }
+        // Shouldn't be possible!
+        Q_ASSERT(status != QSettings::Status::FormatError);
+
+        if (status == QSettings::Status::AccessError)
+            qCritical() << "An access error occurred (e.g. trying to write to a read-only file).";
 
-    try
-    {
-        FS::write(fileName, outArray);
-    }
-    catch (const Exception &e)
-    {
-        qCritical() << e.what();
         return false;
     }
 
     return true;
 }
 
-
 bool INIFile::loadFile(QString fileName)
 {
-    QFile file(fileName);
+    QSettings _settings_obj{ fileName, QSettings::Format::IniFormat };
-    if (!file.open(QIODevice::ReadOnly))
+    _settings_obj.setFallbacksEnabled(false);
+
+    if (auto status = _settings_obj.status(); status != QSettings::Status::NoError) {
+        if (status == QSettings::Status::AccessError)
+            qCritical() << "An access error occurred (e.g. trying to write to a read-only file).";
+        if (status == QSettings::Status::FormatError)
+            qCritical() << "A format error occurred (e.g. loading a malformed INI file).";
         return false;
-    bool success = loadFile(file.readAll());
-    file.close();
-    return success;
-}
-
-bool INIFile::loadFile(QByteArray file)
-{
-    QTextStream in(file);
-#if QT_VERSION <= QT_VERSION_CHECK(6, 0, 0)
-    in.setCodec("UTF-8");
-#endif
-
-    QStringList lines = in.readAll().split('\n');
-    for (int i = 0; i < lines.count(); i++)
-    {
-        QString &lineRaw = lines[i];
-        // Ignore comments.
-        int commentIndex = 0;
-        QString line = lineRaw;
-        // Search for comments until no more escaped # are available
-        while((commentIndex = line.indexOf('#', commentIndex + 1)) != -1) {
-            if(commentIndex > 0 && line.at(commentIndex - 1) == '\\') {
-                continue;
-            }
-            line = line.left(lineRaw.indexOf('#')).trimmed();
     }
 
-        int eqPos = line.indexOf('=');
+    for (auto&& key : _settings_obj.allKeys())
-        if (eqPos == -1)
+        insert(key, _settings_obj.value(key));
-            continue;
-        QString key = line.left(eqPos).trimmed();
-        QString valueStr = line.right(line.length() - eqPos - 1).trimmed();
-
-        valueStr = unescape(valueStr);
-
-        QVariant value(valueStr);
-        this->operator[](key) = value;
-    }
  
     return true;
 }
@@ -183,3 +103,4 @@ void INIFile::set(QString key, QVariant val)
 {
     this->operator[](key) = val;
 }
+

launcher/settings/INIFile.h

@@ -1,4 +1,25 @@
-/* Copyright 2013-2021 MultiMC Contributors
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 Sefa Eyeoglu <contact@scrumplex.net>
+ *  Copyright (C) 2023 flowln <flowlnlnln@gmail.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *
+ *      Copyright 2013-2021 MultiMC Contributors
  *
  *      Licensed under the Apache License, Version 2.0 (the "License");
  *      you may not use this file except in compliance with the License.
@@ -19,18 +40,18 @@
 #include <QVariant>
 #include <QIODevice>
 
+#include <QJsonDocument>
+#include <QJsonArray>
+
 // Sectionless INI parser (for instance config files)
 class INIFile : public QMap<QString, QVariant>
 {
 public:
     explicit INIFile();
 
-    bool loadFile(QByteArray file);
     bool loadFile(QString fileName);
     bool saveFile(QString fileName);
 
     QVariant get(QString key, QVariant def) const;
     void set(QString key, QVariant val);
-    static QString unescape(QString orig);
-    static QString escape(QString orig);
 };

launcher/settings/SettingsObject.h

@@ -19,6 +19,8 @@
 #include <QMap>
 #include <QStringList>
 #include <QVariant>
+#include <QJsonDocument>
+#include <QJsonArray>
 #include <memory>
 
 class Setting;

launcher/ui/MainWindow.cpp

@@ -1337,6 +1337,20 @@ void MainWindow::on_actionDeleteInstance_triggered()
     if (response != QMessageBox::Yes)
         return;
 
+    auto linkedInstances = APPLICATION->instances()->getLinkedInstancesById(id);
+    if (!linkedInstances.empty()) {
+        response = CustomMessageBox::selectable(
+                this, tr("There are linked instances"),
+                tr("The following instance(s) might reference files in this instance:\n\n"
+                "%1\n\n"
+                "Deleting it could break the other instance(s), \n\n"
+                "Do you wish to proceed?", nullptr, linkedInstances.count()).arg(linkedInstances.join("\n")), 
+                QMessageBox::Warning, QMessageBox::Yes | QMessageBox::No, QMessageBox::No
+            )->exec();
+        if (response != QMessageBox::Yes)
+            return;
+    }
+
     if (APPLICATION->instances()->trashInstance(id)) {
         ui->actionUndoTrashInstance->setEnabled(APPLICATION->instances()->trashedSomething());
         return;

launcher/ui/dialogs/CopyInstanceDialog.cpp

@@ -37,18 +37,21 @@
 #include <QPushButton>
 
 #include "Application.h"
+#include "BuildConfig.h"
 #include "CopyInstanceDialog.h"
 #include "ui_CopyInstanceDialog.h"
 
 #include "ui/dialogs/IconPickerDialog.h"
 
-#include "BaseVersion.h"
-#include "icons/IconList.h"
 #include "BaseInstance.h"
+#include "BaseVersion.h"
+#include "DesktopServices.h"
+#include "FileSystem.h"
 #include "InstanceList.h"
+#include "icons/IconList.h"
 
-CopyInstanceDialog::CopyInstanceDialog(InstancePtr original, QWidget *parent)
+CopyInstanceDialog::CopyInstanceDialog(InstancePtr original, QWidget* parent)
-    :QDialog(parent), ui(new Ui::CopyInstanceDialog), m_original(original)
+    : QDialog(parent), ui(new Ui::CopyInstanceDialog), m_original(original)
 {
     ui->setupUi(this);
     resize(minimumSizeHint());
@@ -71,8 +74,7 @@ CopyInstanceDialog::CopyInstanceDialog(InstancePtr original, QWidget *parent)
     groupList.push_front("");
     ui->groupBox->addItems(groupList);
     int index = groupList.indexOf(APPLICATION->instances()->getInstanceGroup(m_original->id()));
-    if(index == -1)
+    if (index == -1) {
-    {
         index = 0;
     }
     ui->groupBox->setCurrentIndex(index);
@@ -85,6 +87,35 @@ CopyInstanceDialog::CopyInstanceDialog(InstancePtr original, QWidget *parent)
     ui->copyServersCheckbox->setChecked(m_selectedOptions.isCopyServersEnabled());
     ui->copyModsCheckbox->setChecked(m_selectedOptions.isCopyModsEnabled());
     ui->copyScreenshotsCheckbox->setChecked(m_selectedOptions.isCopyScreenshotsEnabled());
+
+    ui->symbolicLinksCheckbox->setChecked(m_selectedOptions.isUseSymLinksEnabled());
+    ui->hardLinksCheckbox->setChecked(m_selectedOptions.isUseHardLinksEnabled());
+
+    ui->recursiveLinkCheckbox->setChecked(m_selectedOptions.isLinkRecursivelyEnabled());
+    ui->dontLinkSavesCheckbox->setChecked(m_selectedOptions.isDontLinkSavesEnabled());
+
+    auto detectedFS = FS::statFS(m_original->instanceRoot()).fsType;
+
+    m_cloneSupported = FS::canCloneOnFS(detectedFS);
+    m_linkSupported = FS::canLinkOnFS(detectedFS);
+
+    if (m_cloneSupported) {
+        ui->cloneSupportedLabel->setText(tr("Reflinks are supported on %1").arg(FS::getFilesystemTypeName(detectedFS)));
+    } else {
+        ui->cloneSupportedLabel->setText(tr("Reflinks aren't supported on %1").arg(FS::getFilesystemTypeName(detectedFS)));
+    }
+
+#if defined(Q_OS_WIN)
+    ui->symbolicLinksCheckbox->setIcon(style()->standardIcon(QStyle::SP_VistaShield));
+    ui->symbolicLinksCheckbox->setToolTip(tr("Use symbolic links instead of copying files.") +
+                                          "\n" + tr("On Windows, symbolic links may require admin permission to create."));
+#endif
+
+    updateLinkOptions();
+    updateUseCloneCheckbox();
+
+    auto HelpButton = ui->buttonBox->button(QDialogButtonBox::Help);
+    connect(HelpButton, &QPushButton::clicked, this, &CopyInstanceDialog::help);
 }
 
 CopyInstanceDialog::~CopyInstanceDialog()
@@ -96,8 +127,7 @@ void CopyInstanceDialog::updateDialogState()
 {
     auto allowOK = !instName().isEmpty();
     auto OkButton = ui->buttonBox->button(QDialogButtonBox::Ok);
-    if(OkButton->isEnabled() != allowOK)
+    if (OkButton->isEnabled() != allowOK) {
-    {
         OkButton->setEnabled(allowOK);
     }
 }
@@ -105,8 +135,7 @@ void CopyInstanceDialog::updateDialogState()
 QString CopyInstanceDialog::instName() const
 {
     auto result = ui->instNameTextBox->text().trimmed();
-    if(result.size())
+    if (result.size()) {
-    {
         return result;
     }
     return QString();
@@ -127,6 +156,11 @@ const InstanceCopyPrefs& CopyInstanceDialog::getChosenOptions() const
     return m_selectedOptions;
 }
 
+void CopyInstanceDialog::help()
+{
+    DesktopServices::openUrl(QUrl(BuildConfig.HELP_URL.arg("instance-copy")));
+}
+
 void CopyInstanceDialog::checkAllCheckboxes(const bool& b)
 {
     ui->keepPlaytimeCheckbox->setChecked(b);
@@ -147,20 +181,46 @@ void CopyInstanceDialog::updateSelectAllCheckbox()
     ui->selectAllCheckbox->blockSignals(false);
 }
 
+void CopyInstanceDialog::updateUseCloneCheckbox()
+{
+    ui->useCloneCheckbox->setEnabled(m_cloneSupported && !ui->symbolicLinksCheckbox->isChecked() && !ui->hardLinksCheckbox->isChecked());
+    ui->useCloneCheckbox->setChecked(m_cloneSupported && m_selectedOptions.isUseCloneEnabled() && !ui->symbolicLinksCheckbox->isChecked() &&
+                                     !ui->hardLinksCheckbox->isChecked());
+}
+
+void CopyInstanceDialog::updateLinkOptions()
+{
+    ui->symbolicLinksCheckbox->setEnabled(m_linkSupported && !ui->hardLinksCheckbox->isChecked() && !ui->useCloneCheckbox->isChecked());
+    ui->hardLinksCheckbox->setEnabled(m_linkSupported && !ui->symbolicLinksCheckbox->isChecked() && !ui->useCloneCheckbox->isChecked());
+
+    ui->symbolicLinksCheckbox->setChecked(m_linkSupported && m_selectedOptions.isUseSymLinksEnabled() &&
+                                          !ui->useCloneCheckbox->isChecked());
+    ui->hardLinksCheckbox->setChecked(m_linkSupported && m_selectedOptions.isUseHardLinksEnabled() && !ui->useCloneCheckbox->isChecked());
+
+    bool linksInUse = (ui->symbolicLinksCheckbox->isChecked() || ui->hardLinksCheckbox->isChecked());
+    ui->recursiveLinkCheckbox->setEnabled(m_linkSupported && linksInUse && !ui->hardLinksCheckbox->isChecked());
+    ui->dontLinkSavesCheckbox->setEnabled(m_linkSupported && linksInUse);
+    ui->recursiveLinkCheckbox->setChecked(m_linkSupported && linksInUse && m_selectedOptions.isLinkRecursivelyEnabled());
+    ui->dontLinkSavesCheckbox->setChecked(m_linkSupported && linksInUse && m_selectedOptions.isDontLinkSavesEnabled());
+
+#if defined(Q_OS_WIN)
+    auto OkButton = ui->buttonBox->button(QDialogButtonBox::Ok);
+    OkButton->setIcon(m_selectedOptions.isUseSymLinksEnabled() ? style()->standardIcon(QStyle::SP_VistaShield) : QIcon());
+#endif
+}
+
 void CopyInstanceDialog::on_iconButton_clicked()
 {
     IconPickerDialog dlg(this);
     dlg.execWithSelection(InstIconKey);
 
-    if (dlg.result() == QDialog::Accepted)
+    if (dlg.result() == QDialog::Accepted) {
-    {
         InstIconKey = dlg.selectedIconKey;
         ui->iconButton->setIcon(APPLICATION->icons()->getIcon(InstIconKey));
     }
 }
 
-
+void CopyInstanceDialog::on_instNameTextBox_textChanged(const QString& arg1)
-void CopyInstanceDialog::on_instNameTextBox_textChanged(const QString &arg1)
 {
     updateDialogState();
 }
@@ -175,10 +235,10 @@ void CopyInstanceDialog::on_selectAllCheckbox_stateChanged(int state)
 void CopyInstanceDialog::on_copySavesCheckbox_stateChanged(int state)
 {
     m_selectedOptions.enableCopySaves(state == Qt::Checked);
+    ui->dontLinkSavesCheckbox->setChecked((state == Qt::Checked) && ui->dontLinkSavesCheckbox->isChecked());
     updateSelectAllCheckbox();
 }
 
-
 void CopyInstanceDialog::on_keepPlaytimeCheckbox_stateChanged(int state)
 {
     m_selectedOptions.enableKeepPlaytime(state == Qt::Checked);
@@ -220,3 +280,38 @@ void CopyInstanceDialog::on_copyScreenshotsCheckbox_stateChanged(int state)
     m_selectedOptions.enableCopyScreenshots(state == Qt::Checked);
     updateSelectAllCheckbox();
 }
+
+void CopyInstanceDialog::on_symbolicLinksCheckbox_stateChanged(int state)
+{
+    m_selectedOptions.enableUseSymLinks(state == Qt::Checked);
+    updateUseCloneCheckbox();
+    updateLinkOptions();
+}
+
+void CopyInstanceDialog::on_hardLinksCheckbox_stateChanged(int state)
+{
+    m_selectedOptions.enableUseHardLinks(state == Qt::Checked);
+    if (state == Qt::Checked && !ui->recursiveLinkCheckbox->isChecked()) {
+        ui->recursiveLinkCheckbox->setChecked(true);
+    }
+    updateUseCloneCheckbox();
+    updateLinkOptions();
+}
+
+void CopyInstanceDialog::on_recursiveLinkCheckbox_stateChanged(int state)
+{
+    m_selectedOptions.enableLinkRecursively(state == Qt::Checked);
+    updateLinkOptions();
+}
+
+void CopyInstanceDialog::on_dontLinkSavesCheckbox_stateChanged(int state)
+{
+    m_selectedOptions.enableDontLinkSaves(state == Qt::Checked);
+}
+
+void CopyInstanceDialog::on_useCloneCheckbox_stateChanged(int state)
+{
+    m_selectedOptions.enableUseClone(m_cloneSupported && (state == Qt::Checked));
+    updateUseCloneCheckbox();
+    updateLinkOptions();
+}

launcher/ui/dialogs/CopyInstanceDialog.h

@@ -16,22 +16,21 @@
 #pragma once
 
 #include <QDialog>
+#include "BaseInstance.h"
 #include "BaseVersion.h"
 #include "InstanceCopyPrefs.h"
 
 class BaseInstance;
 
-namespace Ui
+namespace Ui {
-{
 class CopyInstanceDialog;
 }
 
-class CopyInstanceDialog : public QDialog
+class CopyInstanceDialog : public QDialog {
-{
     Q_OBJECT
 
-public:
+   public:
-    explicit CopyInstanceDialog(InstancePtr original, QWidget *parent = 0);
+    explicit CopyInstanceDialog(InstancePtr original, QWidget* parent = 0);
     ~CopyInstanceDialog();
 
     void updateDialogState();
@@ -41,10 +40,12 @@ public:
     QString iconKey() const;
     const InstanceCopyPrefs& getChosenOptions() const;
 
-private
+   public slots:
-slots:
+    void help();
+
+   private slots:
     void on_iconButton_clicked();
-    void on_instNameTextBox_textChanged(const QString &arg1);
+    void on_instNameTextBox_textChanged(const QString& arg1);
     // Checkboxes
     void on_selectAllCheckbox_stateChanged(int state);
     void on_copySavesCheckbox_stateChanged(int state);
@@ -55,13 +56,23 @@ slots:
     void on_copyServersCheckbox_stateChanged(int state);
     void on_copyModsCheckbox_stateChanged(int state);
     void on_copyScreenshotsCheckbox_stateChanged(int state);
+    void on_symbolicLinksCheckbox_stateChanged(int state);
+    void on_hardLinksCheckbox_stateChanged(int state);
+    void on_recursiveLinkCheckbox_stateChanged(int state);
+    void on_dontLinkSavesCheckbox_stateChanged(int state);
+    void on_useCloneCheckbox_stateChanged(int state);
 
-private:
+   private:
     void checkAllCheckboxes(const bool& b);
     void updateSelectAllCheckbox();
+    void updateUseCloneCheckbox();
+    void updateLinkOptions();
+
     /* data */
-    Ui::CopyInstanceDialog *ui;
+    Ui::CopyInstanceDialog* ui;
     QString InstIconKey;
     InstancePtr m_original;
     InstanceCopyPrefs m_selectedOptions;
+    bool m_cloneSupported = false;
+    bool m_linkSupported = false;
 };

launcher/ui/dialogs/CopyInstanceDialog.ui

@@ -9,8 +9,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>341</width>
+    <width>575</width>
-    <height>399</height>
+    <height>695</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -113,30 +113,18 @@
     </layout>
    </item>
    <item>
-    <layout class="QHBoxLayout" name="selectAllButtonLayout">
+    <widget class="QGroupBox" name="copyOptionsGroup">
-     <item>
+     <property name="title">
-      <widget class="QCheckBox" name="selectAllCheckbox">
+      <string>Instance Copy Options</string>
-       <property name="sizePolicy">
-        <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
-         <horstretch>0</horstretch>
-         <verstretch>0</verstretch>
-        </sizepolicy>
-       </property>
-       <property name="layoutDirection">
-        <enum>Qt::LeftToRight</enum>
      </property>
+     <layout class="QGridLayout" name="copyOptionsLayout">
+      <item row="1" column="0">
+       <widget class="QCheckBox" name="keepPlaytimeCheckbox">
         <property name="text">
-        <string>Select all</string>
+         <string>Keep play time</string>
-       </property>
-       <property name="checked">
-        <bool>false</bool>
         </property>
        </widget>
       </item>
-    </layout>
-   </item>
-   <item>
-    <layout class="QGridLayout" name="copyOptionsLayout">
       <item row="6" column="1">
        <widget class="QCheckBox" name="copyModsCheckbox">
         <property name="toolTip">
@@ -147,6 +135,16 @@
         </property>
        </widget>
       </item>
+      <item row="6" column="0">
+       <widget class="QCheckBox" name="copyResPacksCheckbox">
+        <property name="enabled">
+         <bool>true</bool>
+        </property>
+        <property name="text">
+         <string>Copy resource packs</string>
+        </property>
+       </widget>
+      </item>
       <item row="5" column="0">
        <widget class="QCheckBox" name="copyGameOptionsCheckbox">
         <property name="toolTip">
@@ -157,13 +155,6 @@
         </property>
        </widget>
       </item>
-     <item row="3" column="0">
-      <widget class="QCheckBox" name="copySavesCheckbox">
-       <property name="text">
-        <string>Copy saves</string>
-       </property>
-      </widget>
-     </item>
       <item row="3" column="1">
        <widget class="QCheckBox" name="copyShaderPacksCheckbox">
         <property name="text">
@@ -178,20 +169,10 @@
         </property>
        </widget>
       </item>
-     <item row="6" column="0">
+      <item row="3" column="0">
-      <widget class="QCheckBox" name="copyResPacksCheckbox">
+       <widget class="QCheckBox" name="copySavesCheckbox">
-       <property name="enabled">
-        <bool>true</bool>
-       </property>
         <property name="text">
-        <string>Copy resource packs</string>
+         <string>Copy saves</string>
-       </property>
-      </widget>
-     </item>
-     <item row="1" column="0">
-      <widget class="QCheckBox" name="keepPlaytimeCheckbox">
-       <property name="text">
-        <string>Keep play time</string>
         </property>
        </widget>
       </item>
@@ -202,6 +183,200 @@
         </property>
        </widget>
       </item>
+      <item row="7" column="1">
+       <widget class="QCheckBox" name="selectAllCheckbox">
+        <property name="sizePolicy">
+         <sizepolicy hsizetype="Minimum" vsizetype="Fixed">
+          <horstretch>0</horstretch>
+          <verstretch>0</verstretch>
+         </sizepolicy>
+        </property>
+        <property name="layoutDirection">
+         <enum>Qt::LeftToRight</enum>
+        </property>
+        <property name="text">
+         <string>Select all</string>
+        </property>
+        <property name="checked">
+         <bool>false</bool>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
+   <item>
+    <widget class="Line" name="line_2">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QLabel" name="advancedOptionsLabel">
+     <property name="text">
+      <string>Advanced Copy Options</string>
+     </property>
+     <property name="alignment">
+      <set>Qt::AlignCenter</set>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <layout class="QVBoxLayout" name="copyModeLayout">
+     <item>
+      <widget class="QGroupBox" name="linkFilesGroup">
+       <property name="toolTip">
+        <string>Use symbolic or hard links instead of copying files.</string>
+       </property>
+       <property name="title">
+        <string>Symbolic and Hard Link Options</string>
+       </property>
+       <property name="flat">
+        <bool>false</bool>
+       </property>
+       <property name="checkable">
+        <bool>false</bool>
+       </property>
+       <property name="checked">
+        <bool>false</bool>
+       </property>
+       <layout class="QVBoxLayout" name="linkOptionsLayout">
+        <item>
+         <widget class="QLabel" name="linkOptionsLabel">
+          <property name="text">
+           <string>Links are supported on most filesystems except FAT</string>
+          </property>
+          <property name="alignment">
+           <set>Qt::AlignCenter</set>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <layout class="QGridLayout" name="linkOptionsGridLayout" rowstretch="0,0,0,0" columnstretch="0,0" rowminimumheight="0,0,0,0" columnminimumwidth="0,0">
+          <property name="leftMargin">
+           <number>6</number>
+          </property>
+          <property name="topMargin">
+           <number>6</number>
+          </property>
+          <property name="rightMargin">
+           <number>6</number>
+          </property>
+          <property name="bottomMargin">
+           <number>6</number>
+          </property>
+          <item row="2" column="1">
+           <widget class="QCheckBox" name="recursiveLinkCheckbox">
+            <property name="enabled">
+             <bool>false</bool>
+            </property>
+            <property name="toolTip">
+             <string>Link each resource individually instead of linking whole folders at once</string>
+            </property>
+            <property name="text">
+             <string>Link files recursively</string>
+            </property>
+           </widget>
+          </item>
+          <item row="3" column="1">
+           <widget class="QCheckBox" name="dontLinkSavesCheckbox">
+            <property name="enabled">
+             <bool>false</bool>
+            </property>
+            <property name="toolTip">
+             <string>If &quot;copy saves&quot; is selected world save data will be copied instead of linked and thus not shared between instances.</string>
+            </property>
+            <property name="text">
+             <string>Don't link saves</string>
+            </property>
+            <property name="checked">
+             <bool>false</bool>
+            </property>
+           </widget>
+          </item>
+          <item row="3" column="0">
+           <widget class="QCheckBox" name="hardLinksCheckbox">
+            <property name="enabled">
+             <bool>true</bool>
+            </property>
+            <property name="toolTip">
+             <string>Use hard links instead of copying files.</string>
+            </property>
+            <property name="text">
+             <string>Use hard links</string>
+            </property>
+           </widget>
+          </item>
+          <item row="2" column="0">
+           <widget class="QCheckBox" name="symbolicLinksCheckbox">
+            <property name="toolTip">
+             <string>Use symbolic links instead of copying files.</string>
+            </property>
+            <property name="text">
+             <string>Use symbolic links</string>
+            </property>
+           </widget>
+          </item>
+         </layout>
+        </item>
+       </layout>
+      </widget>
+     </item>
+     <item>
+      <widget class="QGroupBox" name="horizontalGroupBox">
+       <property name="title">
+        <string>CoW (Copy-on-Write) Options</string>
+       </property>
+       <layout class="QHBoxLayout" name="useCloneLayout">
+        <item>
+         <widget class="QCheckBox" name="useCloneCheckbox">
+          <property name="enabled">
+           <bool>false</bool>
+          </property>
+          <property name="toolTip">
+           <string>Files cloned with reflinks take up no extra space until they are modified.</string>
+          </property>
+          <property name="text">
+           <string>Clone instead of copying</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <spacer name="CoWSpacer">
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+          <property name="sizeHint" stdset="0">
+           <size>
+            <width>40</width>
+            <height>20</height>
+           </size>
+          </property>
+         </spacer>
+        </item>
+        <item>
+         <widget class="QLabel" name="cloneSupportedLabel">
+          <property name="sizePolicy">
+           <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
+            <horstretch>1</horstretch>
+            <verstretch>0</verstretch>
+           </sizepolicy>
+          </property>
+          <property name="text">
+           <string>Your filesystem and/or OS doesn't support reflinks</string>
+          </property>
+          <property name="alignment">
+           <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
+          </property>
+          <property name="margin">
+           <number>4</number>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </widget>
+     </item>
     </layout>
    </item>
    <item>
@@ -210,7 +385,7 @@
       <enum>Qt::Horizontal</enum>
      </property>
      <property name="standardButtons">
-      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Help|QDialogButtonBox::Ok</set>
      </property>
     </widget>
    </item>
@@ -220,10 +395,21 @@
   <tabstop>iconButton</tabstop>
   <tabstop>instNameTextBox</tabstop>
   <tabstop>groupBox</tabstop>
+  <tabstop>keepPlaytimeCheckbox</tabstop>
+  <tabstop>copyScreenshotsCheckbox</tabstop>
+  <tabstop>copySavesCheckbox</tabstop>
+  <tabstop>copyShaderPacksCheckbox</tabstop>
+  <tabstop>copyGameOptionsCheckbox</tabstop>
+  <tabstop>copyServersCheckbox</tabstop>
+  <tabstop>copyResPacksCheckbox</tabstop>
+  <tabstop>copyModsCheckbox</tabstop>
+  <tabstop>symbolicLinksCheckbox</tabstop>
+  <tabstop>recursiveLinkCheckbox</tabstop>
+  <tabstop>hardLinksCheckbox</tabstop>
+  <tabstop>dontLinkSavesCheckbox</tabstop>
+  <tabstop>useCloneCheckbox</tabstop>
  </tabstops>
- <resources>
+ <resources/>
-  <include location="../../graphics.qrc"/>
- </resources>
  <connections>
   <connection>
    <sender>buttonBox</sender>
@@ -232,8 +418,8 @@
    <slot>accept()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>254</x>
+     <x>269</x>
-     <y>316</y>
+     <y>692</y>
     </hint>
     <hint type="destinationlabel">
      <x>157</x>
@@ -248,8 +434,8 @@
    <slot>reject()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>322</x>
+     <x>337</x>
-     <y>316</y>
+     <y>692</y>
     </hint>
     <hint type="destinationlabel">
      <x>286</x>

launcher/ui/dialogs/ExportInstanceDialog.cpp

@@ -45,6 +45,8 @@
 #include <QDebug>
 #include <QSaveFile>
 #include <QStack>
+#include <QFileInfo>
+
 #include "StringUtils.h"
 #include "SeparatorPrefixTree.h"
 #include "Application.h"
@@ -429,7 +431,8 @@ bool ExportInstanceDialog::doExport()
         QMessageBox::warning(this, tr("Error"), tr("Unable to export instance"));
         return false;
     }
-    if (!MMCZip::compressDirFiles(output, m_instance->instanceRoot(), files))
+
+    if (!MMCZip::compressDirFiles(output, m_instance->instanceRoot(), files, true))
     {
         QMessageBox::warning(this, tr("Error"), tr("Unable to export instance"));
         return false;

launcher/ui/pages/instance/WorldListPage.cpp

@@ -107,6 +107,7 @@ WorldListPage::WorldListPage(BaseInstance *inst, std::shared_ptr<WorldList> worl
     auto head = ui->worldTreeView->header();
     head->setSectionResizeMode(0, QHeaderView::Stretch);
     head->setSectionResizeMode(1, QHeaderView::ResizeToContents);
+    head->setSectionResizeMode(4, QHeaderView::ResizeToContents);
 
     connect(ui->worldTreeView->selectionModel(), &QItemSelectionModel::currentChanged, this, &WorldListPage::worldChanged);
     worldChanged(QModelIndex(), QModelIndex());

program_info/win_install.nsi.in

@@ -281,6 +281,7 @@ Section "@Launcher_DisplayName@"
   SetOutPath $INSTDIR
 
   File "@Launcher_APP_BINARY_NAME@.exe"
+  File "@Launcher_APP_BINARY_NAME@_filelink.exe"
   File "qt.conf"
   File *.dll
   File /r "iconengines"
@@ -361,6 +362,7 @@ Section "Uninstall"
   DeleteRegKey HKCU SOFTWARE\@Launcher_CommonName@
 
   Delete $INSTDIR\@Launcher_APP_BINARY_NAME@.exe
+  Delete $INSTDIR\@Launcher_APP_BINARY_NAME@_filelink.exe
   Delete $INSTDIR\qt.conf
   Delete $INSTDIR\*.dll
 

tests/FileSystem_test.cpp

@@ -1,11 +1,104 @@
 #include <QTest>
+#include <QDir>
 #include <QTemporaryDir>
 #include <QStandardPaths>
 
+#include <tasks/Task.h>
+
 #include <FileSystem.h>
+#include <StringUtils.h>
+
+// Snippet from https://github.com/gulrak/filesystem#using-it-as-single-file-header
+
+#ifdef __APPLE__
+#include <Availability.h> // for deployment target to support pre-catalina targets without std::fs
+#endif // __APPLE__
+
+#if ((defined(_MSVC_LANG) && _MSVC_LANG >= 201703L) || (defined(__cplusplus) && __cplusplus >= 201703L)) && defined(__has_include)
+#if __has_include(<filesystem>) && (!defined(__MAC_OS_X_VERSION_MIN_REQUIRED) || __MAC_OS_X_VERSION_MIN_REQUIRED >= 101500)
+#define GHC_USE_STD_FS
+#include <filesystem>
+namespace fs = std::filesystem;
+#endif // MacOS min version check
+#endif // Other OSes version check
+
+#ifndef GHC_USE_STD_FS
+#include <ghc/filesystem.hpp>
+namespace fs = ghc::filesystem;
+#endif
 
 #include <pathmatcher/RegexpMatcher.h>
 
+
+
+class LinkTask : public Task {
+    Q_OBJECT
+
+    friend class FileSystemTest;
+
+    LinkTask(QString src, QString dst)
+    {
+        m_lnk = new FS::create_link(src, dst, this);
+        m_lnk->debug(true);
+    }
+
+    void matcher(const IPathMatcher *filter)
+    {
+        m_lnk->matcher(filter);
+    }
+
+    void linkRecursively(bool recursive) 
+    {
+        m_lnk->linkRecursively(recursive);
+        m_linkRecursive = recursive;
+    }
+
+    void whitelist(bool b)
+    {
+        m_lnk->whitelist(b);
+    }
+
+    void setMaxDepth(int depth)
+    {
+        m_lnk->setMaxDepth(depth);
+    }
+
+   private:
+    void executeTask() override
+    {
+        if(!(*m_lnk)()){
+#if defined Q_OS_WIN32
+            if (!m_useHard) {
+                qDebug() << "EXPECTED: Link failure, Windows requires permissions for symlinks";
+
+                qDebug() << "atempting to run with privelage";
+                connect(m_lnk, &FS::create_link::finishedPrivileged, this, [&](bool gotResults){
+                    if (gotResults) {
+                        emitSucceeded();
+                    } else {
+                        qDebug() << "Privileged run exited without results!";
+                        emitFailed();
+                    }
+                });
+                m_lnk->runPrivileged();
+            } else {
+                qDebug() << "Link Failed!" << m_lnk->getOSError().value() << m_lnk->getOSError().message().c_str();
+            }      
+#else
+            qDebug() << "Link Failed!" << m_lnk->getOSError().value() << m_lnk->getOSError().message().c_str();
+#endif
+        } else {
+            emitSucceeded();
+        }
+        
+    };
+
+    FS::create_link *m_lnk;
+    bool m_useHard = false;
+    bool m_linkRecursive = true;
+};
+
+
 class FileSystemTest : public QObject
 {
     Q_OBJECT
@@ -248,6 +341,447 @@ slots:
     {
         QCOMPARE(FS::getDesktopDir(), QStandardPaths::writableLocation(QStandardPaths::DesktopLocation));
     }
+
+
+    void test_link()
+    {
+        QString folder = QFINDTESTDATA("testdata/FileSystem/test_folder");
+        auto f = [&folder, this]()
+        {
+            QTemporaryDir tempDir;
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+
+            LinkTask lnk_tsk(folder, target_dir.path());
+            lnk_tsk.linkRecursively(false);
+            QObject::connect(&lnk_tsk, &Task::finished, [&]{ 
+                QVERIFY2(lnk_tsk.wasSuccessful(), "Task finished but was not successful when it should have been."); 
+            });
+            lnk_tsk.start();
+
+            QVERIFY2(QTest::qWaitFor([&]() {
+                return lnk_tsk.isFinished();
+            }, 100000), "Task didn't finish as it should.");
+
+            for(auto entry: target_dir.entryList())
+            {
+                qDebug() << entry;
+                QFileInfo entry_lnk_info(target_dir.filePath(entry));
+                if (!entry_lnk_info.isDir())
+                    QVERIFY(!entry_lnk_info.isSymLink());
+            }
+
+            QFileInfo lnk_info(target_dir.path());
+            QVERIFY(lnk_info.exists());
+            QVERIFY(lnk_info.isSymLink());
+
+            QVERIFY(target_dir.entryList().contains("pack.mcmeta"));
+            QVERIFY(target_dir.entryList().contains("assets"));
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_hard_link()
+    {
+        QString folder = QFINDTESTDATA("testdata/FileSystem/test_folder");
+        auto f = [&folder]()
+        {   
+            // use working dir to prevent makeing a hard link to a tmpfs or across devices
+            QTemporaryDir tempDir("./tmp"); 
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+            FS::create_link lnk(folder, target_dir.path());
+            lnk.useHardLinks(true);
+            lnk.debug(true);
+            if(!lnk()){
+                qDebug() << "Link Failed!" << lnk.getOSError().value() << lnk.getOSError().message().c_str();
+            }
+
+            for(auto entry: target_dir.entryList())
+            {
+                qDebug() << entry;
+                QFileInfo entry_lnk_info(target_dir.filePath(entry));
+                QVERIFY(!entry_lnk_info.isSymLink());
+                QFileInfo entry_orig_info(QDir(folder).filePath(entry));
+                if (!entry_lnk_info.isDir()) {
+                    qDebug() << "hard link equivalency?" << entry_lnk_info.absoluteFilePath() << "vs" << entry_orig_info.absoluteFilePath();
+                    QVERIFY(fs::equivalent(
+                        fs::path(StringUtils::toStdString(entry_lnk_info.absoluteFilePath())),
+                        fs::path(StringUtils::toStdString(entry_orig_info.absoluteFilePath()))
+                    ));
+                } 
+            }
+
+            QFileInfo lnk_info(target_dir.path());
+            QVERIFY(lnk_info.exists());
+            QVERIFY(!lnk_info.isSymLink());
+
+            QVERIFY(target_dir.entryList().contains("pack.mcmeta"));
+            QVERIFY(target_dir.entryList().contains("assets"));
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_link_with_blacklist()
+    {
+        QString folder = QFINDTESTDATA("testdata/FileSystem/test_folder");
+        auto f = [&folder]()
+        {
+            QTemporaryDir tempDir;
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+
+            LinkTask lnk_tsk(folder, target_dir.path());
+            lnk_tsk.matcher(new RegexpMatcher("[.]?mcmeta"));
+            lnk_tsk.linkRecursively(true);
+            QObject::connect(&lnk_tsk, &Task::finished, [&]{ 
+                QVERIFY2(lnk_tsk.wasSuccessful(), "Task finished but was not successful when it should have been."); 
+            });
+            lnk_tsk.start();
+
+            QVERIFY2(QTest::qWaitFor([&]() {
+                return lnk_tsk.isFinished();
+            }, 100000), "Task didn't finish as it should.");
+
+
+            for(auto entry: target_dir.entryList())
+            {
+                qDebug() << entry;
+                QFileInfo entry_lnk_info(target_dir.filePath(entry));
+                if (!entry_lnk_info.isDir())
+                    QVERIFY(entry_lnk_info.isSymLink());
+            }
+
+            QFileInfo lnk_info(target_dir.path());
+            QVERIFY(lnk_info.exists());
+
+            QVERIFY(!target_dir.entryList().contains("pack.mcmeta"));
+            QVERIFY(target_dir.entryList().contains("assets"));
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_link_with_whitelist()
+    {
+        QString folder = QFINDTESTDATA("testdata/FileSystem/test_folder");
+        auto f = [&folder]()
+        {
+            QTemporaryDir tempDir;
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+
+            LinkTask lnk_tsk(folder, target_dir.path());
+            lnk_tsk.matcher(new RegexpMatcher("[.]?mcmeta"));
+            lnk_tsk.linkRecursively(true);
+            lnk_tsk.whitelist(true);
+            QObject::connect(&lnk_tsk, &Task::finished, [&]{ 
+                QVERIFY2(lnk_tsk.wasSuccessful(), "Task finished but was not successful when it should have been."); 
+            });
+            lnk_tsk.start();
+
+            QVERIFY2(QTest::qWaitFor([&]() {
+                return lnk_tsk.isFinished();
+            }, 100000), "Task didn't finish as it should.");
+
+            for(auto entry: target_dir.entryList())
+            {
+                qDebug() << entry;
+                QFileInfo entry_lnk_info(target_dir.filePath(entry));
+                if (!entry_lnk_info.isDir())
+                    QVERIFY(entry_lnk_info.isSymLink());
+            }
+
+            QFileInfo lnk_info(target_dir.path());
+            QVERIFY(lnk_info.exists());
+
+            QVERIFY(target_dir.entryList().contains("pack.mcmeta"));
+            QVERIFY(!target_dir.entryList().contains("assets"));
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_link_with_dot_hidden()
+    {
+        QString folder = QFINDTESTDATA("testdata/FileSystem/test_folder");
+        auto f = [&folder]()
+        {
+            QTemporaryDir tempDir;
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+
+            LinkTask lnk_tsk(folder, target_dir.path());
+            lnk_tsk.linkRecursively(true);
+            QObject::connect(&lnk_tsk, &Task::finished, [&]{ 
+                QVERIFY2(lnk_tsk.wasSuccessful(), "Task finished but was not successful when it should have been."); 
+            });
+            lnk_tsk.start();
+
+            QVERIFY2(QTest::qWaitFor([&]() {
+                return lnk_tsk.isFinished();
+            }, 100000), "Task didn't finish as it should.");
+
+            auto filter = QDir::Filter::Files | QDir::Filter::Dirs | QDir::Filter::Hidden;
+
+            for (auto entry: target_dir.entryList(filter)) {
+                qDebug() << entry;
+                QFileInfo entry_lnk_info(target_dir.filePath(entry));
+                if (!entry_lnk_info.isDir())
+                    QVERIFY(entry_lnk_info.isSymLink());
+            }
+
+            QFileInfo lnk_info(target_dir.path());
+            QVERIFY(lnk_info.exists());
+
+            QVERIFY(target_dir.entryList(filter).contains(".secret_folder"));
+            target_dir.cd(".secret_folder");
+            QVERIFY(target_dir.entryList(filter).contains(".secret_file.txt"));
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_link_single_file()
+    {
+        QTemporaryDir tempDir;
+        tempDir.setAutoRemove(true);
+
+        {
+            QString file = QFINDTESTDATA("testdata/FileSystem/test_folder/pack.mcmeta");
+
+            qDebug() << "From:" << file << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "pack.mcmeta"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+
+            LinkTask lnk_tsk(file,  target_dir.filePath("pack.mcmeta"));
+            QObject::connect(&lnk_tsk, &Task::finished, [&]{ 
+                QVERIFY2(lnk_tsk.wasSuccessful(), "Task finished but was not successful when it should have been."); 
+            });
+            lnk_tsk.start();
+
+            QVERIFY2(QTest::qWaitFor([&]() {
+                return lnk_tsk.isFinished();
+            }, 100000), "Task didn't finish as it should.");
+
+            auto filter = QDir::Filter::Files;
+
+            for (auto entry: target_dir.entryList(filter)) {
+                qDebug() << entry;
+            }
+
+            QFileInfo lnk_info(target_dir.filePath("pack.mcmeta"));
+            QVERIFY(lnk_info.exists());
+            QVERIFY(lnk_info.isSymLink());
+
+            QVERIFY(target_dir.entryList(filter).contains("pack.mcmeta"));
+        }
+    }
+
+    void test_link_with_max_depth()
+    {
+        QString folder = QFINDTESTDATA("testdata/FileSystem/test_folder");
+        auto f = [&folder, this]()
+        {
+            QTemporaryDir tempDir;
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+
+            LinkTask lnk_tsk(folder, target_dir.path());
+            lnk_tsk.linkRecursively(true);
+            lnk_tsk.setMaxDepth(0);
+            QObject::connect(&lnk_tsk, &Task::finished, [&]{ 
+                QVERIFY2(lnk_tsk.wasSuccessful(), "Task finished but was not successful when it should have been."); 
+            });
+            lnk_tsk.start();
+
+            QVERIFY2(QTest::qWaitFor([&]() {
+                return lnk_tsk.isFinished();
+            }, 100000), "Task didn't finish as it should.");
+
+            QVERIFY(!QFileInfo(target_dir.path()).isSymLink());
+
+            auto filter = QDir::Filter::Files | QDir::Filter::Dirs | QDir::Filter::Hidden;
+            for(auto entry: target_dir.entryList(filter))
+            {
+                qDebug() << entry;
+                if (entry == "." || entry == "..") continue;
+                QFileInfo entry_lnk_info(target_dir.filePath(entry));
+                QVERIFY(entry_lnk_info.isSymLink());
+            }
+
+            QFileInfo lnk_info(target_dir.path());
+            QVERIFY(lnk_info.exists());
+            QVERIFY(!lnk_info.isSymLink());
+
+            QVERIFY(target_dir.entryList().contains("pack.mcmeta"));
+            QVERIFY(target_dir.entryList().contains("assets"));
+
+
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_link_with_no_max_depth()
+    {
+        QString folder = QFINDTESTDATA("testdata/FileSystem/test_folder");
+        auto f = [&folder]()
+        {
+            QTemporaryDir tempDir;
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+
+            LinkTask lnk_tsk(folder, target_dir.path());
+            lnk_tsk.linkRecursively(true);
+            lnk_tsk.setMaxDepth(-1);
+            QObject::connect(&lnk_tsk, &Task::finished, [&]{ 
+                QVERIFY2(lnk_tsk.wasSuccessful(), "Task finished but was not successful when it should have been."); 
+            });
+            lnk_tsk.start();
+
+            QVERIFY2(QTest::qWaitFor([&]() {
+                return lnk_tsk.isFinished();
+            }, 100000), "Task didn't finish as it should.");
+
+
+            std::function<void(QString)> verify_check = [&](QString check_path) {
+                QDir check_dir(check_path);
+                auto filter = QDir::Filter::Files | QDir::Filter::Dirs | QDir::Filter::Hidden;
+                for(auto entry: check_dir.entryList(filter))
+                {
+                    QFileInfo entry_lnk_info(check_dir.filePath(entry));
+                    qDebug() << entry << check_dir.filePath(entry);
+                    if (!entry_lnk_info.isDir()){
+                        QVERIFY(entry_lnk_info.isSymLink());
+                    } else if (entry != "." && entry != "..") {
+                        qDebug() << "Decending tree to verify symlinks:" << check_dir.filePath(entry);
+                        verify_check(entry_lnk_info.filePath());
+                    }
+                }
+            };
+            
+            verify_check(target_dir.path());
+            
+
+            QFileInfo lnk_info(target_dir.path());
+            QVERIFY(lnk_info.exists());
+
+            QVERIFY(target_dir.entryList().contains("pack.mcmeta"));
+            QVERIFY(target_dir.entryList().contains("assets"));
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_path_depth() {
+        QCOMPARE(FS::pathDepth(""), 0);
+        QCOMPARE(FS::pathDepth("."), 0);
+        QCOMPARE(FS::pathDepth("foo.txt"), 0);
+        QCOMPARE(FS::pathDepth("./foo.txt"), 0);
+        QCOMPARE(FS::pathDepth("./bar/foo.txt"), 1);
+        QCOMPARE(FS::pathDepth("../bar/foo.txt"), 0);
+        QCOMPARE(FS::pathDepth("/bar/foo.txt"), 1);
+        QCOMPARE(FS::pathDepth("baz/bar/foo.txt"), 2);
+        QCOMPARE(FS::pathDepth("/baz/bar/foo.txt"), 2);
+        QCOMPARE(FS::pathDepth("./baz/bar/foo.txt"), 2);
+        QCOMPARE(FS::pathDepth("/baz/../bar/foo.txt"), 1);
+    }
+
+    void test_path_trunc() {
+        QCOMPARE(FS::pathTruncate("", 0), QDir::toNativeSeparators(""));
+        QCOMPARE(FS::pathTruncate("foo.txt", 0), QDir::toNativeSeparators(""));
+        QCOMPARE(FS::pathTruncate("foo.txt", 1), QDir::toNativeSeparators(""));
+        QCOMPARE(FS::pathTruncate("./bar/foo.txt", 0), QDir::toNativeSeparators("./bar"));
+        QCOMPARE(FS::pathTruncate("./bar/foo.txt", 1), QDir::toNativeSeparators("./bar"));
+        QCOMPARE(FS::pathTruncate("/bar/foo.txt", 1), QDir::toNativeSeparators("/bar"));
+        QCOMPARE(FS::pathTruncate("bar/foo.txt", 1), QDir::toNativeSeparators("bar"));
+        QCOMPARE(FS::pathTruncate("baz/bar/foo.txt", 2), QDir::toNativeSeparators("baz/bar"));
+#if defined(Q_OS_WIN)
+        QCOMPARE(FS::pathTruncate("C:\\bar\\foo.txt", 1), QDir::toNativeSeparators("C:\\bar"));
+#endif
+    }
 };
 
 QTEST_GUILESS_MAIN(FileSystemTest)

tests/INIFile_test.cpp

@@ -1,7 +1,11 @@
 #include <QTest>
 
+#include <QList>
+#include <QVariant>
 #include <settings/INIFile.h>
 
+#include <QVariantUtils.h>
+
 class IniFileTest : public QObject
 {
     Q_OBJECT
@@ -27,15 +31,6 @@ slots:
         QTest::newRow("Escape sequences 2") << "\"\n\n\"";
         QTest::newRow("Hashtags") << "some data#something";
     }
-    void test_Escape()
-    {
-        QFETCH(QString, through);
-
-        QString there = INIFile::escape(through);
-        QString back = INIFile::unescape(there);
-
-        QCOMPARE(back, through);
-    }
 
     void test_SaveLoad()
     {
@@ -52,8 +47,37 @@ slots:
         // load
         INIFile f2;
         f2.loadFile(filename);
-        QCOMPARE(a, f2.get("a","NOT SET").toString());
+        QCOMPARE(f2.get("a","NOT SET").toString(), a);
-        QCOMPARE(b, f2.get("b","NOT SET").toString());
+        QCOMPARE(f2.get("b","NOT SET").toString(), b);
+    }
+
+    void test_SaveLoadLists()
+    {
+        QString slist_strings = "(\"a\",\"b\",\"c\")";
+        QStringList list_strings = {"a", "b", "c"};
+
+        QString slist_numbers = "(1,2,3,10)";
+        QList<int> list_numbers = {1, 2, 3, 10};
+
+        QString filename = "test_SaveLoadLists.ini";
+
+        INIFile f;
+        f.set("list_strings", list_strings);
+        f.set("list_numbers", QVariantUtils::fromList(list_numbers));
+        f.saveFile(filename);
+
+        // load
+        INIFile f2;
+        f2.loadFile(filename);
+
+        QStringList out_list_strings = f2.get("list_strings", QStringList()).toStringList();
+        qDebug() << "OutStringList" << out_list_strings;
+        
+        QList<int> out_list_numbers = QVariantUtils::toList<int>(f2.get("list_numbers", QVariantUtils::fromList(QList<int>())));
+        qDebug() << "OutNumbersList" << out_list_numbers;
+
+        QCOMPARE(out_list_strings, list_strings);
+        QCOMPARE(out_list_numbers, list_numbers);
     }
 };
 

tests/ResourceFolderModel_test.cpp

@@ -36,6 +36,7 @@
 #include <QTest>
 #include <QTemporaryDir>
 #include <QTimer>
+#include "BaseInstance.h"
 
 #include <FileSystem.h>
 
@@ -89,7 +90,9 @@ slots:
 
             QEventLoop loop;
 
-            ModFolderModel m(tempDir.path(), true);
+            InstancePtr instance;
+
+            ModFolderModel m(tempDir.path(), instance, true);
 
             connect(&m, &ModFolderModel::updateFinished, &loop, &QEventLoop::quit);
 
@@ -113,7 +116,8 @@ slots:
             QString folder = source + '/';
             QTemporaryDir tempDir;
             QEventLoop loop;
-            ModFolderModel m(tempDir.path(), true);
+            InstancePtr instance;
+            ModFolderModel m(tempDir.path(), instance, true);
 
             connect(&m, &ModFolderModel::updateFinished, &loop, &QEventLoop::quit);
 
@@ -136,8 +140,8 @@ slots:
     void test_addFromWatch()
     {
         QString source = QFINDTESTDATA("testdata/ResourceFolderModel");
-
+        InstancePtr instance;
-        ModFolderModel model(source);
+        ModFolderModel model(source, instance);
 
         QCOMPARE(model.size(), 0);
 
@@ -157,8 +161,9 @@ slots:
         QString file_mod = QFINDTESTDATA("testdata/ResourceFolderModel/supercoolmod.jar");
 
         QTemporaryDir tmp;
+        InstancePtr instance;
 
-        ResourceFolderModel model(QDir(tmp.path()));
+        ResourceFolderModel model(QDir(tmp.path()), instance);
 
         QCOMPARE(model.size(), 0);
 
@@ -209,7 +214,8 @@ slots:
         QString file_mod = QFINDTESTDATA("testdata/ResourceFolderModel/supercoolmod.jar");
 
         QTemporaryDir tmp;
-        ResourceFolderModel model(tmp.path());
+        InstancePtr instance;
+        ResourceFolderModel model(tmp.path(), instance);
 
         QCOMPARE(model.size(), 0);