Add FUSE external mapping support, BG3/Oblivion Remastered fixes, fomod-plus and NaK integration

FUSE VFS now deploys non-data-dir mod mappings (Paks, OBSE, UE4SS, etc.)
via real symlinks and injects file-level data-dir mappings (plugins.txt,
loadorder.txt) into the VFS tree. Fixes game launches for Oblivion
Remastered (Root Builder path resolution, script extender support) and
BG3 (Wine prefix documents directory, file mapper symlinks on Linux).

Vendors mo2-fomod-plus plugin and NaK crate for FOMOD installer and
game finder/runtime support.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 98 insertions, 0 deletions

diff --git a/libs/installer_fomod_plus/scanner/archiveparser.h b/libs/installer_fomod_plus/scanner/archiveparser.h
new file mode 100644
index 0000000..4058d43
--- /dev/null
+++ b/libs/installer_fomod_plus/scanner/archiveparser.h
@@ -0,0 +1,98 @@
+#pragma once
+#include "stringutil.h"
+
+#include <QDir>
+#include <QString>
+#include <archive.h>
+#include <iostream>
+#include <ostream>
+
+inline std::ostream& operator<<(std::ostream& os, const Archive::Error& error)
+{
+    switch (error) {
+    case Archive::Error::ERROR_NONE:
+        os << "No error";
+        break;
+    case Archive::Error::ERROR_ARCHIVE_NOT_FOUND:
+        os << "File not found";
+        break;
+    case Archive::Error::ERROR_FAILED_TO_OPEN_ARCHIVE:
+        os << "Failed to open file";
+        break;
+    case Archive::Error::ERROR_INVALID_ARCHIVE_FORMAT:
+        os << "Invalid archive format";
+        break;
+    default:
+        os << "Unknown error??";
+    }
+    return os;
+}
+
+inline bool hasFomodFiles(const std::vector<FileData*>& files)
+{
+    bool hasModuleXml = false;
+    bool hasInfoXml   = false;
+
+    for (const auto* file : files) {
+        if (endsWithCaseInsensitive(file->getArchiveFilePath(), StringConstants::FomodFiles::W_MODULE_CONFIG.data())) {
+            hasModuleXml = true;
+        }
+        if (endsWithCaseInsensitive(file->getArchiveFilePath(), StringConstants::FomodFiles::W_INFO_XML.data())) {
+            hasInfoXml = true;
+        }
+    }
+    return hasModuleXml && hasInfoXml;
+}
+
+/* This class can do the following:
+ * 1.) Detects if an archive has FOMOD files in it (without extracting)
+ *      - This is used by the FOMOD scanner to set content flags
+ *
+ * 2.) It may support extracting ESPs and FOMODs, but this might be better served
+ *     by a separate class. Maybe it could return a ModuleConfiguration to use like
+ *     the installer.
+ */
+
+enum class ScanResult {
+    HAS_FOMOD,
+    NO_FOMOD,
+    NO_ARCHIVE
+};
+
+class ArchiveParser {
+public:
+    static ScanResult scanForFomodFiles(const QString& downloadsPath, const QString& installationFilePath,
+        const QString& modName)
+    {
+        if (installationFilePath.isEmpty()) {
+            return ScanResult::NO_ARCHIVE;
+        }
+        const auto qualifiedInstallerPath = QDir(installationFilePath).isAbsolute()
+            ? installationFilePath
+            : downloadsPath + "/" + installationFilePath;
+
+        const auto archive = CreateArchive();
+
+        if (!archive->isValid()) {
+            logErrorForMod(modName, "Failed to load the archive module ", archive);
+            return ScanResult::NO_ARCHIVE;
+        }
+        if (!archive->open(qualifiedInstallerPath.toStdWString(), nullptr)) {
+            logErrorForMod(modName, "Failed to open archive [" + qualifiedInstallerPath + "]", archive);
+            return ScanResult::NO_ARCHIVE;
+        }
+
+        if (hasFomodFiles(archive->getFileList())) {
+            std::cout << "Found FOMOD files in " << qualifiedInstallerPath.toStdString() << std::endl;
+            return ScanResult::HAS_FOMOD;
+        }
+        return ScanResult::NO_FOMOD;
+    }
+
+private:
+    static void logErrorForMod(const QString& modName, const QString& message, const std::unique_ptr<Archive>& archive)
+    {
+        std::cerr << "[" << modName.toStdString() << "] " << message.toStdString() << " (" << archive->getLastError() <<
+            ")" << std::endl;
+    }
+};
\ No newline at end of file