FS: Stream RomFS from file instead of loading all of it to memory

4 files changed, 20 insertions, 9 deletions

diff --git a/src/core/loader/loader.cpp b/src/core/loader/loader.cpp
index 2e450fce..b6549daf 100644
--- a/src/core/loader/loader.cpp
+++ b/src/core/loader/loader.cpp
@@ -124,7 +124,7 @@ ResultStatus LoadFile(const std::string& filename) {
     case FileType::CXI:
     case FileType::CCI:
     {
-        AppLoader_NCCH app_loader(std::move(file));
+        AppLoader_NCCH app_loader(std::move(file), filename);
 
         // Load application and RomFS
         if (ResultStatus::Success == app_loader.Load()) {
diff --git a/src/core/loader/loader.h b/src/core/loader/loader.h
index 52bbf35b..ff298222 100644
--- a/src/core/loader/loader.h
+++ b/src/core/loader/loader.h
@@ -99,10 +99,13 @@ public:
 
     /**
      * Get the RomFS of the application
-     * @param buffer Reference to buffer to store data
+     * Since the RomFS can be huge, we return a file reference instead of copying to a buffer
+     * @param romfs_file The file containing the RomFS
+     * @param offset The offset the romfs begins on
+     * @param size The size of the romfs
      * @return ResultStatus result of function
      */
-    virtual ResultStatus ReadRomFS(std::vector<u8>& buffer) const {
+    virtual ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset, u64& size) const {
         return ResultStatus::ErrorNotImplemented;
     }
 
diff --git a/src/core/loader/ncch.cpp b/src/core/loader/ncch.cpp
index 87603d19..2bf1a6a2 100644
--- a/src/core/loader/ncch.cpp
+++ b/src/core/loader/ncch.cpp
@@ -299,7 +299,7 @@ ResultStatus AppLoader_NCCH::ReadLogo(std::vector<u8>& buffer) const {
     return LoadSectionExeFS("logo", buffer);
 }
 
-ResultStatus AppLoader_NCCH::ReadRomFS(std::vector<u8>& buffer) const {
+ResultStatus AppLoader_NCCH::ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset, u64& size) const {
     if (!file->IsOpen())
         return ResultStatus::Error;
 
@@ -311,12 +311,17 @@ ResultStatus AppLoader_NCCH::ReadRomFS(std::vector<u8>& buffer) const {
         LOG_DEBUG(Loader, "RomFS offset:           0x%08X", romfs_offset);
         LOG_DEBUG(Loader, "RomFS size:             0x%08X", romfs_size);
 
-        buffer.resize(romfs_size);
+        if (file->GetSize () < romfs_offset + romfs_size)
+            return ResultStatus::Error;
 
-        file->Seek(romfs_offset, SEEK_SET);
-        if (file->ReadBytes(&buffer[0], romfs_size) != 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, "NCCH has no RomFS");
diff --git a/src/core/loader/ncch.h b/src/core/loader/ncch.h
index 29e39d2c..d180e77e 100644
--- a/src/core/loader/ncch.h
+++ b/src/core/loader/ncch.h
@@ -163,7 +163,8 @@ namespace Loader {
 /// Loads an NCCH file (e.g. from a CCI, or the first NCCH in a CXI)
 class AppLoader_NCCH final : public AppLoader {
 public:
-    AppLoader_NCCH(std::unique_ptr<FileUtil::IOFile>&& file) : AppLoader(std::move(file)) { }
+    AppLoader_NCCH(std::unique_ptr<FileUtil::IOFile>&& file, const std::string& filepath)
+        : AppLoader(std::move(file)), filepath(filepath) { }
 
     /**
      * Returns the type of the file
@@ -211,7 +212,7 @@ public:
      * @param buffer Reference to buffer to store data
      * @return ResultStatus result of function
      */
-    ResultStatus ReadRomFS(std::vector<u8>& buffer) const override;
+    ResultStatus ReadRomFS(std::shared_ptr<FileUtil::IOFile>& romfs_file, u64& offset, u64& size) const override;
 
 private:
 
@@ -244,6 +245,8 @@ private:
     NCCH_Header     ncch_header;
     ExeFs_Header    exefs_header;
     ExHeader_Header exheader_header;
+
+    std::string     filepath;
 };
 
 } // namespace Loader