default:
		return n, nil
	}
}

func (fw *regFileWriter) ReadFrom(r io.Reader) (int64, error) {
	return io.Copy(struct{ io.Writer }{fw}, r)
}

// logicalRemaining implements fileState.logicalRemaining.
func (fw regFileWriter) logicalRemaining() int64 {
	return fw.nb
}

// physicalRemaining implements fileState.physicalRemaining.
func (fw regFileWriter) physicalRemaining() int64 {
	return fw.nb
}

	default:
		return n, err
	}
}

func (fr *regFileReader) WriteTo(w io.Writer) (int64, error) {
	return io.Copy(w, struct{ io.Reader }{fr})
}

// logicalRemaining implements fileState.logicalRemaining.
func (fr regFileReader) logicalRemaining() int64 {
	return fr.nb
}

// physicalRemaining implements fileState.physicalRemaining.
func (fr regFileReader) physicalRemaining() int64 {
	return fr.nb
}

				}
				if len(f.ops) > 0 {
					t.Errorf("test %d.%d, expected %d more operations", i, j, len(f.ops))
				}
			case testRemaining:
				if got := fw.logicalRemaining(); got != tf.wantLCnt {
					t.Errorf("test %d.%d, logicalRemaining() = %d, want %d", i, j, got, tf.wantLCnt)
				}
				if got := fw.physicalRemaining(); got != tf.wantPCnt {

				}
				if len(f.ops) > 0 {
					t.Errorf("test %d.%d, expected %d more operations", i, j, len(f.ops))
				}
			case testRemaining:
				if got := fr.logicalRemaining(); got != tf.wantLCnt {
					t.Errorf("test %d.%d, logicalRemaining() = %d, want %d", i, j, got, tf.wantLCnt)
				}
				if got := fr.physicalRemaining(); got != tf.wantPCnt {

}

// fileState tracks the number of logical (includes sparse holes) and physical
// (actual in tar archive) bytes remaining for the current file.
//
// Invariant: logicalRemaining >= physicalRemaining
type fileState interface {
	logicalRemaining() int64
	physicalRemaining() int64
}

// allowedFormats determines which formats can be used.
// The value returned is the logical OR of multiple possible formats.