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// Copyright 2021 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package executor
import (
"bufio"
"fmt"
"io"
"io/fs"
"os"
"path/filepath"
"strconv"
"strings"
"github.com/pingcap/tiup/pkg/utils"
"golang.org/x/crypto/ssh"
)
// ScpDownload downloads a file from remote with SCP
// The implementation is partially inspired by github.com/dtylman/scp
// Do not support pattern, src and dst must be dir or file path
func ScpDownload(session *ssh.Session, client *ssh.Client, src, dst string, limit int, compress bool) error {
r, err := session.StdoutPipe()
if err != nil {
return err
}
bufr := bufio.NewReader(r)
w, err := session.StdinPipe()
if err != nil {
return err
}
remoteArgs := make([]string, 0)
if compress {
remoteArgs = append(remoteArgs, "-C")
}
if limit > 0 {
remoteArgs = append(remoteArgs, fmt.Sprintf("-l %d", limit))
}
remoteCmd := fmt.Sprintf("scp -r %s -f %s", strings.Join(remoteArgs, " "), src)
err = session.Start(remoteCmd)
if err != nil {
return err
}
if err := ack(w); err != nil { // send an empty byte to start transfer
return err
}
wd := dst
for firstCommand := true; ; firstCommand = false {
// parse scp command
line, err := bufr.ReadString('\n')
if err == io.EOF {
break
} else if err != nil {
return err
}
switch line[0] {
// ignore ACK from server
case '\x00':
line = line[1:]
case '\x01':
return fmt.Errorf("scp warning: %s", line[1:])
case '\x02':
return fmt.Errorf("scp error: %s", line[1:])
}
switch line[0] {
case 'C':
mode, size, name, err := parseLine(line)
if err != nil {
return err
}
fp := filepath.Join(wd, name)
// first scp command is 'C' means src is a single file
if firstCommand {
fp = dst
}
targetFile, err := os.OpenFile(fp, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode|0700)
if err != nil {
return err
}
defer targetFile.Close()
if err := ack(w); err != nil {
return err
}
// transferring data
n, err := io.CopyN(targetFile, bufr, size)
if err != nil {
return err
}
if n < size {
return fmt.Errorf("error downloading via scp, file size mismatch")
}
if err := targetFile.Sync(); err != nil {
return err
}
case 'D':
mode, _, name, err := parseLine(line)
if err != nil {
return err
}
// normally, workdir is like this
wd = filepath.Join(wd, name)
// first scp command is 'D' means src is a dir
if firstCommand {
fi, err := os.Stat(dst)
if err != nil && !os.IsNotExist(err) {
return err
} else if err == nil && !fi.IsDir() {
return fmt.Errorf("%s cannot be an exist file", wd)
} else if os.IsNotExist(err) {
// dst is not exist, so dst is the target dir
wd = dst
} else {
// dst is exist, dst/name is the target dir
break
}
}
err = utils.MkdirAll(wd, mode)
if err != nil {
return err
}
case 'E':
wd = filepath.Dir(wd)
default:
return fmt.Errorf("incorrect scp command '%b', should be 'C', 'D' or 'E'", line[0])
}
err = ack(w)
if err != nil {
return err
}
}
return session.Wait()
}
func ack(w io.Writer) error {
msg := []byte("\x00")
n, err := w.Write(msg)
if err != nil {
return fmt.Errorf("fail to send response to remote: %s", err)
}
if n < len(msg) {
return fmt.Errorf("fail to send response to remote, size mismatch")
}
return nil
}
func parseLine(line string) (mode fs.FileMode, size int64, name string, err error) {
words := strings.Fields(strings.TrimSuffix(line, "\n"))
if len(words) < 3 {
return 0, 0, "", fmt.Errorf("incorrect scp command param number: %d", len(words))
}
modeN, err := strconv.ParseUint(words[0][1:], 0, 32)
if err != nil {
return 0, 0, "", fmt.Errorf("error parsing file mode; %s", err)
}
mode = fs.FileMode(modeN)
size, err = strconv.ParseInt(words[1], 10, 64)
if err != nil {
return 0, 0, "", err
}
name = words[2]
return
}
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