DirectoryBlob: Let DiscContent be backed by memory instead of file

2 files changed, 30 insertions, 5 deletions

diff --git a/Source/Core/DiscIO/DirectoryBlob.cpp b/Source/Core/DiscIO/DirectoryBlob.cpp
index a974e882d6..8f000454e8 100644
--- a/Source/Core/DiscIO/DirectoryBlob.cpp
+++ b/Source/Core/DiscIO/DirectoryBlob.cpp
@@ -14,6 +14,7 @@
 #include <set>
 #include <string>
 #include <utility>
+#include <variant>
 #include <vector>
 
 #include "Common/Align.h"
@@ -50,7 +51,12 @@ const std::array<u32, 10> PARTITION_TABLE = {
      Common::swap32(GAME_PARTITION_ADDRESS >> 2), 0}};
 
 DiscContent::DiscContent(u64 offset, u64 size, const std::string& path)
-    : m_offset(offset), m_size(size), m_path(path)
+    : m_offset(offset), m_size(size), m_content_source(path)
+{
+}
+
+DiscContent::DiscContent(u64 offset, u64 size, const u8* data)
+    : m_offset(offset), m_size(size), m_content_source(data)
 {
 }
 
@@ -80,10 +86,18 @@ bool DiscContent::Read(u64* offset, u64* length, u8** buffer) const
   {
     const u64 bytes_to_read = std::min(m_size - offset_in_content, *length);
 
-    File::IOFile file(m_path, "rb");
-    file.Seek(offset_in_content, SEEK_SET);
-    if (!file.ReadBytes(*buffer, bytes_to_read))
-      return false;
+    if (std::holds_alternative<std::string>(m_content_source))
+    {
+      File::IOFile file(std::get<std::string>(m_content_source), "rb");
+      file.Seek(offset_in_content, SEEK_SET);
+      if (!file.ReadBytes(*buffer, bytes_to_read))
+        return false;
+    }
+    else
+    {
+      const u8* const content_pointer = std::get<const u8*>(m_content_source) + offset_in_content;
+      std::copy(content_pointer, content_pointer + bytes_to_read, *buffer);
+    }
 
     *length -= bytes_to_read;
     *buffer += bytes_to_read;
diff --git a/Source/Core/DiscIO/DirectoryBlob.h b/Source/Core/DiscIO/DirectoryBlob.h
index 3e4683b906..f3879c97f6 100644
--- a/Source/Core/DiscIO/DirectoryBlob.h
+++ b/Source/Core/DiscIO/DirectoryBlob.h
@@ -9,6 +9,7 @@
 #include <optional>
 #include <set>
 #include <string>
+#include <variant>
 #include <vector>
 
 #include "Common/CommonTypes.h"
@@ -26,7 +27,10 @@ namespace DiscIO
 class DiscContent
 {
 public:
+  using ContentSource = std::variant<std::string, const u8*>;
+
   DiscContent(u64 offset, u64 size, const std::string& path);
+  DiscContent(u64 offset, u64 size, const u8* data);
 
   // Provided because it's convenient when searching for DiscContent in an std::set
   explicit DiscContent(u64 offset);
@@ -45,6 +49,7 @@ private:
   u64 m_offset;
   u64 m_size = 0;
   std::string m_path;
+  ContentSource m_content_source;
 };
 
 class DirectoryBlobReader : public BlobReader
@@ -53,6 +58,12 @@ public:
   static bool IsValidDirectoryBlob(const std::string& dol_path);
   static std::unique_ptr<DirectoryBlobReader> Create(File::IOFile dol, const std::string& dol_path);
 
+  // We do not allow copying, because it might mess up the pointers inside DiscContents
+  DirectoryBlobReader(const DirectoryBlobReader&) = delete;
+  DirectoryBlobReader& operator=(const DirectoryBlobReader&) = delete;
+  DirectoryBlobReader(DirectoryBlobReader&&) = default;
+  DirectoryBlobReader& operator=(DirectoryBlobReader&&) = default;
+
   bool Read(u64 offset, u64 length, u8* buffer) override;
   bool SupportsReadWiiDecrypted() const override;
   bool ReadWiiDecrypted(u64 offset, u64 size, u8* buffer, u64 partition_offset) override;