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

src/core/file_sys/archive_romfs.cpp

@@ -17,16 +17,15 @@
 
 namespace FileSys {
 
-ArchiveFactory_RomFS::ArchiveFactory_RomFS(const Loader::AppLoader& app_loader)
+ArchiveFactory_RomFS::ArchiveFactory_RomFS(const Loader::AppLoader& app_loader) {
-        : romfs_data(std::make_shared<std::vector<u8>>()) {
     // Load the RomFS from the app
-    if (Loader::ResultStatus::Success != app_loader.ReadRomFS(*romfs_data)) {
+    if (Loader::ResultStatus::Success != app_loader.ReadRomFS(romfs_file, data_offset, data_size)) {
         LOG_ERROR(Service_FS, "Unable to read RomFS!");
     }
 }
 
 ResultVal<std::unique_ptr<ArchiveBackend>> ArchiveFactory_RomFS::Open(const Path& path) {
-    auto archive = Common::make_unique<IVFCArchive>(romfs_data);
+    auto archive = Common::make_unique<IVFCArchive>(romfs_file, data_offset, data_size);
     return MakeResult<std::unique_ptr<ArchiveBackend>>(std::move(archive));
 }
 

src/core/file_sys/archive_romfs.h

@@ -29,7 +29,9 @@ public:
     ResultCode Format(const Path& path) override;
 
 private:
-    std::shared_ptr<std::vector<u8>> romfs_data;
+    std::shared_ptr<FileUtil::IOFile> romfs_file;
+    u64 data_offset;
+    u64 data_size;
 };
 
 } // namespace FileSys

src/core/file_sys/archive_savedatacheck.cpp

@@ -37,17 +37,14 @@ ResultVal<std::unique_ptr<ArchiveBackend>> ArchiveFactory_SaveDataCheck::Open(co
     auto vec = path.AsBinary();
     const u32* data = reinterpret_cast<u32*>(vec.data());
     std::string file_path = GetSaveDataCheckPath(mount_point, data[1], data[0]);
-    FileUtil::IOFile file(file_path, "rb");
+    auto file = std::make_shared<FileUtil::IOFile>(file_path, "rb");
 
-    if (!file.IsOpen()) {
+    if (!file->IsOpen()) {
         return ResultCode(-1); // TODO(Subv): Find the right error code
     }
-    auto size = file.GetSize();
+    auto size = file->GetSize();
-    auto raw_data = std::make_shared<std::vector<u8>>(size);
-    file.ReadBytes(raw_data->data(), size);
-    file.Close();
 
-    auto archive = Common::make_unique<IVFCArchive>(std::move(raw_data));
+    auto archive = Common::make_unique<IVFCArchive>(file, 0, size);
     return MakeResult<std::unique_ptr<ArchiveBackend>>(std::move(archive));
 }
 

src/core/file_sys/ivfc_archive.cpp

@@ -16,15 +16,12 @@
 
 namespace FileSys {
 
-IVFCArchive::IVFCArchive(std::shared_ptr<const std::vector<u8>> data) : data(data) {
-}
-
 std::string IVFCArchive::GetName() const {
     return "IVFC";
 }
 
 std::unique_ptr<FileBackend> IVFCArchive::OpenFile(const Path& path, const Mode mode) const {
-    return Common::make_unique<IVFCFile>(data);
+    return Common::make_unique<IVFCFile>(romfs_file, data_offset, data_size);
 }
 
 bool IVFCArchive::DeleteFile(const Path& path) const {
@@ -66,8 +63,10 @@ std::unique_ptr<DirectoryBackend> IVFCArchive::OpenDirectory(const Path& path) c
 
 size_t IVFCFile::Read(const u64 offset, const u32 length, u8* buffer) const {
     LOG_TRACE(Service_FS, "called offset=%llu, length=%d", offset, length);
-    memcpy(buffer, data->data() + offset, length);
+    romfs_file->Seek(data_offset + offset, SEEK_SET);
-    return length;
+    u32 read_length = (u32)std::min((u64)length, data_size - offset);
+
+    return romfs_file->ReadBytes(buffer, read_length);
 }
 
 size_t IVFCFile::Write(const u64 offset, const u32 length, const u32 flush, const u8* buffer) const {
@@ -76,7 +75,7 @@ size_t IVFCFile::Write(const u64 offset, const u32 length, const u32 flush, cons
 }
 
 size_t IVFCFile::GetSize() const {
-    return sizeof(u8) * data->size();
+    return data_size; // TODO: return value will overflow on 32-bit machines
 }
 
 bool IVFCFile::SetSize(const u64 size) const {

src/core/file_sys/ivfc_archive.h

@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "common/common_types.h"
+#include "common/file_util.h"
 
 #include "core/file_sys/archive_backend.h"
 #include "core/file_sys/directory_backend.h"
@@ -28,7 +29,8 @@ namespace FileSys {
  */
 class IVFCArchive : public ArchiveBackend {
 public:
-    IVFCArchive(std::shared_ptr<const std::vector<u8>> data);
+    IVFCArchive(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size)
+        : romfs_file(file), data_offset(offset), data_size(size) {}
 
     std::string GetName() const override;
 
@@ -42,12 +44,15 @@ public:
     std::unique_ptr<DirectoryBackend> OpenDirectory(const Path& path) const override;
 
 protected:
-    std::shared_ptr<const std::vector<u8>> data;
+    std::shared_ptr<FileUtil::IOFile> romfs_file;
+    u64 data_offset;
+    u64 data_size;
 };
 
 class IVFCFile : public FileBackend {
 public:
-    IVFCFile(std::shared_ptr<const std::vector<u8>> data) : data(data) {}
+    IVFCFile(std::shared_ptr<FileUtil::IOFile> file, u64 offset, u64 size)
+        : romfs_file(file), data_offset(offset), data_size(size) {}
 
     bool Open() override { return true; }
     size_t Read(const u64 offset, const u32 length, u8* buffer) const override;
@@ -58,7 +63,9 @@ public:
     void Flush() const override { }
 
 private:
-    std::shared_ptr<const std::vector<u8>> data;
+    std::shared_ptr<FileUtil::IOFile> romfs_file;
+    u64 data_offset;
+    u64 data_size;
 };
 
 class IVFCDirectory : public DirectoryBackend {

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()) {

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;
     }
 

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)
-
-        file->Seek(romfs_offset, SEEK_SET);
-        if (file->ReadBytes(&buffer[0], romfs_size) != romfs_size)
             return ResultStatus::Error;
 
+        // 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");

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