package toreader import "io" type Reader struct { r io.ReaderAt offset int64 } func NewReader(r io.ReaderAt, start int64) *Reader { return &Reader{ r: r, offset: start, } } func (r *Reader) Read(b []byte) (int, error) { n, err := r.r.ReadAt(b, r.offset) r.offset += int64(n) return n, err }