Function fetch

coderd/files/cache.go:290–323

(store database.Store, fileID uuid.UUID)

}

func fetch(store database.Store, fileID uuid.UUID) (CacheEntryValue, error) {
	// Because many callers can be waiting on the same file fetch concurrently, we
	// want to prevent any failures that would cause them all to receive errors
	// because the caller who initiated the fetch would fail.
	// - We always run the fetch with an uncancelable context, and then check
	//   context cancellation for each acquirer afterwards.
	// - We always run the fetch as a system user, and then check authorization
	//   for each acquirer afterwards.
	// This prevents a canceled context or an unauthorized user from "holding up
	// the queue".
	//nolint:gocritic
	file, err := store.GetFileByID(dbauthz.AsFileReader(context.Background()), fileID)
	if err != nil {
		return CacheEntryValue{}, xerrors.Errorf("failed to read file from database: %w", err)
	}

	var files fs.FS
	switch file.Mimetype {
	case "application/zip", "application/x-zip-compressed":
		files, err = archivefs.FromZipReader(bytes.NewReader(file.Data), int64(len(file.Data)))
		if err != nil {
			return CacheEntryValue{}, xerrors.Errorf("failed to read zip file: %w", err)
		}
	default:
		// Assume '"application/x-tar"' as the default mimetype.
		files = archivefs.FromTarReader(bytes.NewBuffer(file.Data))
	}

	return CacheEntryValue{
		Object: file.RBACObject(),
		FS:     files,
		Size:   int64(len(file.Data)),
	}, nil
}