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
}
if me.flags&missinggo.O_ACCMODE == os.O_WRONLY {
err = errors.New("read flags missing")
return
}
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 := me.fs.Client.Do(req)
if err != nil {
return
}
switch resp.StatusCode {
case http.StatusPartialContent:
cr, ok := httptoo.ParseBytesContentRange(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)
}
case http.StatusNotFound:
err = ErrNotFound
resp.Body.Close()
return
default:
err = errors.New(resp.Status)
resp.Body.Close()
return
}
me.r = resp.Body
me.rOff = me.off
return
}
// ok is false if the response just doesn't specify anything we handle.
func instanceLength(r *http.Response) (l int64, err error) {
switch r.StatusCode {
case http.StatusOK:
l, err = strconv.ParseInt(r.Header.Get("Content-Length"), 10, 64)
return
case http.StatusPartialContent:
cr, parseOk := httptoo.ParseBytesContentRange(r.Header.Get("Content-Range"))
l = cr.Length
if !parseOk {
err = errors.New("error parsing Content-Range")
}
return
default:
err = errors.New("unhandled status code")
return
}
}