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package httpfile
import (
"bytes"
"errors"
"fmt"
"io"
"net/http"
"os"
"strconv"
"github.com/anacrolix/missinggo"
"github.com/anacrolix/missinggo/httptoo"
)
type File struct {
off int64
r io.ReadCloser
rOff int64
length int64
url string
flags int
fs *FS
}
func (me *File) headLength() (err error) {
l, err := me.fs.GetLength(me.url)
if err != nil {
return
}
if l != -1 {
me.length = l
}
return
}
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
}
func (me *File) Read(b []byte) (n int, err error) {
err = me.prepareReader()
if err != nil {
return
}
n, err = me.r.Read(b)
me.off += int64(n)
me.rOff += int64(n)
return
}
func (me *File) Seek(offset int64, whence int) (ret int64, err error) {
switch whence {
case os.SEEK_SET:
ret = offset
case os.SEEK_CUR:
ret = me.off + offset
case os.SEEK_END:
// Try to update the resource length.
err = me.headLength()
if err != nil {
if me.length == -1 {
// Don't even have an old value.
return
}
err = nil
}
ret = me.length + offset
default:
err = fmt.Errorf("unhandled whence: %d", whence)
return
}
me.off = ret
return
}
func (me *File) Write(b []byte) (n int, err error) {
if me.flags&(os.O_WRONLY|os.O_RDWR) == 0 || me.flags&os.O_CREATE == 0 {
err = errors.New("cannot write without write and create flags")
return
}
req, err := http.NewRequest("PATCH", me.url, bytes.NewReader(b))
if err != nil {
return
}
req.Header.Set("Content-Range", fmt.Sprintf("bytes=%d-", me.off))
req.ContentLength = int64(len(b))
resp, err := me.fs.Client.Do(req)
if err != nil {
return
}
resp.Body.Close()
if resp.StatusCode != http.StatusPartialContent {
err = errors.New(resp.Status)
return
}
n = len(b)
me.off += int64(n)
return
}
func (me *File) Close() error {
me.url = ""
me.length = -1
if me.r != nil {
me.r.Close()
me.r = nil
}
return nil
}
|
