3 files changed, 61 insertions, 3 deletions

diff --git a/src/core/loader/3dsx.cpp b/src/core/loader/3dsx.cpp
index 530837d08..111b6a409 100644
--- a/src/core/loader/3dsx.cpp
+++ b/src/core/loader/3dsx.cpp
@@ -62,6 +62,10 @@ struct THREEDSX_Header
     // Sizes of the code, rodata and data segments +
     // size of the BSS section (uninitialized latter half of the data segment)
     u32 code_seg_size, rodata_seg_size, data_seg_size, bss_size;
+    // offset and size of smdh
+    u32 smdh_offset, smdh_size;
+    // offset to filesystem
+    u32 fs_offset;
 };
 
 // Relocation header: all fields (even extra unknown fields) are guaranteed to be relocation counts.
@@ -267,4 +271,40 @@ ResultStatus AppLoader_THREEDSX::Load() {
     return ResultStatus::Success;
 }
 
+ResultStatus AppLoader_THREEDSX::ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset, u64& size) {
+    if (!file.IsOpen())
+        return ResultStatus::Error;
+
+    // Reset read pointer in case this file has been read before.
+    file.Seek(0, SEEK_SET);
+
+    THREEDSX_Header hdr;
+    if (file.ReadBytes(&hdr, sizeof(THREEDSX_Header)) != sizeof(THREEDSX_Header))
+        return ResultStatus::Error;
+
+    if (hdr.header_size != sizeof(THREEDSX_Header))
+        return ResultStatus::Error;
+
+    // Check if the 3DSX has a RomFS...
+    if (hdr.fs_offset != 0) {
+        u32 romfs_offset = hdr.fs_offset;
+        u32 romfs_size = file.GetSize() - hdr.fs_offset;
+
+        LOG_DEBUG(Loader, "RomFS offset:           0x%08X", romfs_offset);
+        LOG_DEBUG(Loader, "RomFS size:             0x%08X", romfs_size);
+
+        // We reopen the file, to allow its position to be independent from file's
+        romfs_file = std::make_shared<FileUtil::IOFile>(filepath, "rb");
+        if (!romfs_file->IsOpen())
+            return ResultStatus::Error;
+
+        offset = romfs_offset;
+        size = romfs_size;
+
+        return ResultStatus::Success;
+    }
+    LOG_DEBUG(Loader, "3DSX has no RomFS");
+    return ResultStatus::ErrorNotUsed;
+}
+
 } // namespace Loader
diff --git a/src/core/loader/3dsx.h b/src/core/loader/3dsx.h
index a0aa0c533..365ddb7a5 100644
--- a/src/core/loader/3dsx.h
+++ b/src/core/loader/3dsx.h
@@ -17,8 +17,8 @@ namespace Loader {
 /// Loads an 3DSX file
 class AppLoader_THREEDSX final : public AppLoader {
 public:
-    AppLoader_THREEDSX(FileUtil::IOFile&& file, std::string filename)
-        : AppLoader(std::move(file)), filename(std::move(filename)) {}
+    AppLoader_THREEDSX(FileUtil::IOFile&& file, std::string filename, const std::string& filepath)
+        : AppLoader(std::move(file)), filename(std::move(filename)), filepath(filepath) {}
 
     /**
      * Returns the type of the file
@@ -33,8 +33,18 @@ public:
      */
     ResultStatus Load() override;
 
+    /**
+     * Get the RomFS of the application
+     * @param romfs_file Reference to buffer to store data
+     * @param offset     Offset in the file to the RomFS
+     * @param size       Size of the RomFS in bytes
+     * @return ResultStatus result of function
+     */
+    ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset, u64& size) override;
+
 private:
     std::string filename;
+    std::string filepath;
 };
 
 } // namespace Loader
diff --git a/src/core/loader/loader.cpp b/src/core/loader/loader.cpp
index 74eb6e871..c4b4f5a5d 100644
--- a/src/core/loader/loader.cpp
+++ b/src/core/loader/loader.cpp
@@ -116,7 +116,15 @@ ResultStatus LoadFile(const std::string& filename) {
 
     //3DSX file format...
     case FileType::THREEDSX:
-        return AppLoader_THREEDSX(std::move(file), filename_filename).Load();
+    {
+        AppLoader_THREEDSX app_loader(std::move(file), filename_filename, filename);
+        // Load application and RomFS
+        if (ResultStatus::Success == app_loader.Load()) {
+            Service::FS::RegisterArchiveType(Common::make_unique<FileSys::ArchiveFactory_RomFS>(app_loader), Service::FS::ArchiveIdCode::RomFS);
+            return ResultStatus::Success;
+        }
+        break;
+    }
 
     // Standard ELF file format...
     case FileType::ELF: