DiscIO: Move scrubbing code out of ConvertToGCZ

This way, scrubbing can also be performed when converting
to other formats.

Source/Core/DiscIO/ScrubbedBlob.cpp

@@ -0,0 +1,67 @@
+// Copyright 2020 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include "DiscIO/ScrubbedBlob.h"
+
+#include <algorithm>
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "Common/Align.h"
+#include "DiscIO/Blob.h"
+#include "DiscIO/DiscScrubber.h"
+#include "DiscIO/Volume.h"
+
+namespace DiscIO
+{
+ScrubbedBlob::ScrubbedBlob(std::unique_ptr<BlobReader> blob_reader, DiscScrubber scrubber)
+    : m_blob_reader(std::move(blob_reader)), m_scrubber(std::move(scrubber))
+{
+}
+
+std::unique_ptr<ScrubbedBlob> ScrubbedBlob::Create(const std::string& path)
+{
+  std::unique_ptr<VolumeDisc> disc = CreateDisc(path);
+  if (!disc)
+    return nullptr;
+
+  DiscScrubber scrubber;
+  if (!scrubber.SetupScrub(disc.get()))
+    return nullptr;
+
+  std::unique_ptr<BlobReader> blob = CreateBlobReader(path);
+  if (!blob)
+    return nullptr;
+
+  return std::unique_ptr<ScrubbedBlob>(new ScrubbedBlob(std::move(blob), std::move(scrubber)));
+}
+
+bool ScrubbedBlob::Read(u64 offset, u64 size, u8* out_ptr)
+{
+  while (size > 0)
+  {
+    constexpr size_t CLUSTER_SIZE = DiscScrubber::CLUSTER_SIZE;
+    const u64 bytes_to_read =
+        std::min(Common::AlignDown(offset + CLUSTER_SIZE, CLUSTER_SIZE) - offset, size);
+
+    if (m_scrubber.CanBlockBeScrubbed(offset))
+    {
+      std::fill_n(out_ptr, bytes_to_read, 0);
+    }
+    else
+    {
+      if (!m_blob_reader->Read(offset, bytes_to_read, out_ptr))
+        return false;
+    }
+
+    offset += bytes_to_read;
+    size -= bytes_to_read;
+    out_ptr += bytes_to_read;
+  }
+
+  return true;
+}
+
+}  // namespace DiscIO