func (me *File) prepareReader() (err error) {
if me.r != nil && me.off != me.rOff {
me.r.Close()
me.r = nil
}
if me.r != nil {
return nil
}
req, err := http.NewRequest("GET", me.url, nil)
if err != nil {
return
}
if me.off != 0 {
req.Header.Set("Range", fmt.Sprintf("bytes=%d-", me.off))
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return
}
switch resp.StatusCode {
case http.StatusPartialContent:
cr, ok := missinggo.ParseHTTPBytesContentRange(resp.Header.Get("Content-Range"))
if !ok || cr.First != me.off {
err = errors.New("bad response")
resp.Body.Close()
return
}
me.length = cr.Length
case http.StatusOK:
if me.off != 0 {
err = errors.New("bad response")
resp.Body.Close()
return
}
if h := resp.Header.Get("Content-Length"); h != "" {
var cl uint64
cl, err = strconv.ParseUint(h, 10, 64)
if err != nil {
resp.Body.Close()
return
}
me.length = int64(cl)
}
default:
err = errors.New(resp.Status)
resp.Body.Close()
return
}
me.r = resp.Body
me.rOff = me.off
return
}
func instanceLength(r *http.Response) (int64, error) {
switch r.StatusCode {
case http.StatusOK:
if h := r.Header.Get("Content-Length"); h != "" {
return strconv.ParseInt(h, 10, 64)
} else {
return -1, nil
}
case http.StatusPartialContent:
cr, ok := missinggo.ParseHTTPBytesContentRange(r.Header.Get("Content-Range"))
if !ok {
return -1, errors.New("bad 206 response")
}
return cr.Length, nil
default:
return -1, errors.New(r.Status)
}
}