MemoryCardImage: Implement save file importing and exporting

src/core/memory_card_image.cpp

@@ -466,4 +466,95 @@ bool ImportCard(DataArray* data, const char* filename)
   }
 }
 
-} // namespace MemoryCardImage
+bool ExportSave(DataArray* data, const FileInfo& fi, const char* filename)
+{
+  std::unique_ptr<ByteStream> stream =
+    FileSystem::OpenFile(filename, BYTESTREAM_OPEN_CREATE | BYTESTREAM_OPEN_TRUNCATE | BYTESTREAM_OPEN_WRITE |
+                                     BYTESTREAM_OPEN_ATOMIC_UPDATE | BYTESTREAM_OPEN_STREAMED);
+  if (!stream)
+  {
+    Log_ErrorPrintf("Failed to open '%s' for writing.", filename);
+    return false;
+  }
+
+  DirectoryFrame* df_ptr = GetFramePtr<DirectoryFrame>(data, 0, fi.first_block);
+  std::vector<u8> header = std::vector<u8>(static_cast<size_t>(FRAME_SIZE));
+  std::memcpy(header.data(), df_ptr, sizeof(*df_ptr));
+
+  std::vector<u8> blocks;
+  if (!ReadFile(*data, fi, &blocks))
+  {
+    Log_ErrorPrintf("Failed to read save blocks from memory card data");
+    return false;
+  }
+
+  if (!stream->Write(header.data(), static_cast<u32>(header.size())) ||
+      !stream->Write(blocks.data(), static_cast<u32>(blocks.size())) || !stream->Commit())
+  {
+    Log_ErrorPrintf("Failed to write exported save to '%s'", filename);
+    stream->Discard();
+    return false;
+  }
+
+  return true;
+}
+
+bool ImportSave(DataArray* data, const char* filename)
+{
+  FILESYSTEM_STAT_DATA sd;
+  if (!FileSystem::StatFile(filename, &sd))
+  {
+    Log_ErrorPrintf("Failed to stat file '%s'", filename);
+    return false;
+  }
+
+  // Make sure the size of the actual file is valid
+  if (sd.Size <= FRAME_SIZE || (sd.Size - FRAME_SIZE) % BLOCK_SIZE != 0u || (sd.Size - FRAME_SIZE) / BLOCK_SIZE > 15u)
+  {
+    Log_ErrorPrintf("Invalid size for save file '%s'", filename);
+    return false;
+  }
+
+  std::unique_ptr<ByteStream> stream = FileSystem::OpenFile(filename, BYTESTREAM_OPEN_READ | BYTESTREAM_OPEN_STREAMED);
+  if (!stream)
+  {
+    Log_ErrorPrintf("Failed to open '%s' for reading", filename);
+    return false;
+  }
+
+  DirectoryFrame df;
+  if (stream->Read(&df, FRAME_SIZE) != FRAME_SIZE)
+  {
+    Log_ErrorPrintf("Failed to read directory frame from '%s'", filename);
+    return false;
+  }
+
+  // Make sure the size reported by the directory frame is valid
+  if (df.file_size < BLOCK_SIZE || df.file_size % BLOCK_SIZE != 0 || df.file_size / BLOCK_SIZE > 15u)
+  {
+    Log_ErrorPrintf("Invalid size (%u bytes) reported by directory frame", df.file_size);
+    return false;
+  }
+
+  // Make sure there isn't already a save with the same name
+  std::vector<FileInfo> fileinfos = EnumerateFiles(*data);
+  for (const FileInfo& fi : fileinfos)
+  {
+    if (fi.filename.compare(0, sizeof(df.filename), df.filename) == 0)
+    {
+      Log_ErrorPrintf("Save file with the same name already exists in memory card");
+      return false;
+    }
+  }
+
+  std::vector<u8> blocks = std::vector<u8>(static_cast<size_t>(df.file_size));
+  if (stream->Read(blocks.data(), df.file_size) != df.file_size)
+  {
+    Log_ErrorPrintf("Failed to read block bytes from '%s'", filename);
+    return false;
+  }
+
+  return WriteFile(data, df.filename, blocks);
+}
+
+} // namespace MemoryCardImage