File size: 2,159 Bytes
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package ftp
import (
"io"
"os"
"sync"
"sync/atomic"
"time"
"github.com/jlaffaye/ftp"
)
// do others that not defined in Driver interface
func (d *FTP) login() error {
if d.conn != nil {
_, err := d.conn.CurrentDir()
if err == nil {
return nil
}
}
conn, err := ftp.Dial(d.Address, ftp.DialWithShutTimeout(10*time.Second))
if err != nil {
return err
}
err = conn.Login(d.Username, d.Password)
if err != nil {
return err
}
d.conn = conn
return nil
}
// FileReader An FTP file reader that implements io.MFile for seeking.
type FileReader struct {
conn *ftp.ServerConn
resp *ftp.Response
offset atomic.Int64
readAtOffset int64
mu sync.Mutex
path string
size int64
}
func NewFileReader(conn *ftp.ServerConn, path string, size int64) *FileReader {
return &FileReader{
conn: conn,
path: path,
size: size,
}
}
func (r *FileReader) Read(buf []byte) (n int, err error) {
n, err = r.ReadAt(buf, r.offset.Load())
r.offset.Add(int64(n))
return
}
func (r *FileReader) ReadAt(buf []byte, off int64) (n int, err error) {
if off < 0 {
return -1, os.ErrInvalid
}
r.mu.Lock()
defer r.mu.Unlock()
if off != r.readAtOffset {
//have to restart the connection, to correct offset
_ = r.resp.Close()
r.resp = nil
}
if r.resp == nil {
r.resp, err = r.conn.RetrFrom(r.path, uint64(off))
r.readAtOffset = off
if err != nil {
return 0, err
}
}
n, err = r.resp.Read(buf)
r.readAtOffset += int64(n)
return
}
func (r *FileReader) Seek(offset int64, whence int) (int64, error) {
oldOffset := r.offset.Load()
var newOffset int64
switch whence {
case io.SeekStart:
newOffset = offset
case io.SeekCurrent:
newOffset = oldOffset + offset
case io.SeekEnd:
return r.size, nil
default:
return -1, os.ErrInvalid
}
if newOffset < 0 {
// offset out of range
return oldOffset, os.ErrInvalid
}
if newOffset == oldOffset {
// offset not changed, so return directly
return oldOffset, nil
}
r.offset.Store(newOffset)
return newOffset, nil
}
func (r *FileReader) Close() error {
if r.resp != nil {
return r.resp.Close()
}
return nil
}
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