func NewRFile(f *File) (RFile, error) {
	data, err := fileData(f)
	if err != nil {
		return nil, err
	}
	return &file{f: f, data: data, readable: true}, nil
}
NewRFile returns a RFile from a *File.
package vfs
import (
	"bytes"
	"compress/zlib"
	"errors"
	"fmt"
	"io"
	"os"
	"runtime"
	"time"
)
var (
	errFileClosed = errors.New("file is closed")
)