DiscIO: Add a blob reader for Volume files

Source/Core/DiscIO/VolumeFileBlobReader.cpp

@@ -0,0 +1,51 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "DiscIO/VolumeFileBlobReader.h"
+
+#include "DiscIO/Filesystem.h"
+#include "DiscIO/Volume.h"
+
+namespace DiscIO
+{
+std::unique_ptr<VolumeFileBlobReader> VolumeFileBlobReader::Create(const Volume& volume,
+                                                                   const FileSystem& file_system,
+                                                                   const std::string& file_path)
+{
+  if (!file_system.IsValid())
+    return nullptr;
+
+  std::unique_ptr<FileInfo> file_info = file_system.FindFileInfo(file_path);
+  if (!file_info || file_info->IsDirectory())
+    return nullptr;
+
+  return std::unique_ptr<VolumeFileBlobReader>{
+      new VolumeFileBlobReader(volume, file_system, std::move(file_info))};
+}
+
+VolumeFileBlobReader::VolumeFileBlobReader(const Volume& volume, const FileSystem& file_system,
+                                           std::unique_ptr<FileInfo> file_info)
+    : m_volume(volume), m_file_system(file_system), m_file_info(std::move(file_info))
+{
+}
+
+u64 VolumeFileBlobReader::GetDataSize() const
+{
+  return m_file_info->GetSize();
+}
+
+u64 VolumeFileBlobReader::GetRawSize() const
+{
+  return GetDataSize();
+}
+
+bool VolumeFileBlobReader::Read(u64 offset, u64 length, u8* out_ptr)
+{
+  if (offset + length > m_file_info->GetSize())
+    return false;
+
+  return m_volume.Read(m_file_info->GetOffset() + offset, length, out_ptr,
+                       m_file_system.GetPartition());
+}
+}  // namespace