Created scp.go image_scp_test.go and podman-image-scp.1.md

added functionality for image secure copying from local to remote.
Also moved system connection add code around a bit so functions within that file
can be used by scp.

Signed-off-by: cdoern <cdoern@redhat.com>

vendor/github.com/dtylman/scp/scp.go

@@ -0,0 +1,153 @@
+package scp
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/crypto/ssh"
+)
+
+const (
+	fileMode = "0644"
+	buffSize = 1024 * 256
+)
+
+//CopyTo copy from local to remote
+func CopyTo(sshClient *ssh.Client, local string, remote string) (int64, error) {
+	session, err := sshClient.NewSession()
+	if err != nil {
+		return 0, err
+	}
+	defer session.Close()
+	stderr := &bytes.Buffer{}
+	session.Stderr = stderr
+	stdout := &bytes.Buffer{}
+	session.Stdout = stdout
+	writer, err := session.StdinPipe()
+	if err != nil {
+		return 0, err
+	}
+	defer writer.Close()
+	err = session.Start("scp -t " + filepath.Dir(remote))
+	if err != nil {
+		return 0, err
+	}
+
+	localFile, err := os.Open(local)
+	if err != nil {
+		return 0, err
+	}
+	fileInfo, err := localFile.Stat()
+	if err != nil {
+		return 0, err
+	}
+	_, err = fmt.Fprintf(writer, "C%s %d %s\n", fileMode, fileInfo.Size(), filepath.Base(remote))
+	if err != nil {
+		return 0, err
+	}
+	n, err := copyN(writer, localFile, fileInfo.Size())
+	if err != nil {
+		return 0, err
+	}
+	err = ack(writer)
+	if err != nil {
+		return 0, err
+	}
+
+	err = session.Wait()
+	log.Debugf("Copied %v bytes out of %v. err: %v stdout:%v. stderr:%v", n, fileInfo.Size(), err, stdout, stderr)
+	//NOTE: Process exited with status 1 is not an error, it just how scp work. (waiting for the next control message and we send EOF)
+	return n, nil
+}
+
+//CopyFrom copy from remote to local
+func CopyFrom(sshClient *ssh.Client, remote string, local string) (int64, error) {
+	session, err := sshClient.NewSession()
+	if err != nil {
+		return 0, err
+	}
+	defer session.Close()
+	stderr := &bytes.Buffer{}
+	session.Stderr = stderr
+	writer, err := session.StdinPipe()
+	if err != nil {
+		return 0, err
+	}
+	defer writer.Close()
+	reader, err := session.StdoutPipe()
+	if err != nil {
+		return 0, err
+	}
+	err = session.Start("scp -f " + remote)
+	if err != nil {
+		return 0, err
+	}
+	err = ack(writer)
+	if err != nil {
+		return 0, err
+	}
+	msg, err := NewMessageFromReader(reader)
+	if err != nil {
+		return 0, err
+	}
+	if msg.Type == ErrorMessage || msg.Type == WarnMessage {
+		return 0, msg.Error
+	}
+	log.Debugf("Receiving %v", msg)
+
+	err = ack(writer)
+	if err != nil {
+		return 0, err
+	}
+	outFile, err := os.Create(local)
+	if err != nil {
+		return 0, err
+	}
+	defer outFile.Close()
+	n, err := copyN(outFile, reader, msg.Size)
+	if err != nil {
+		return 0, err
+	}
+	err = outFile.Sync()
+	if err != nil {
+		return 0, err
+	}
+	err = outFile.Close()
+	if err != nil {
+		return 0, err
+	}
+	err = session.Wait()
+	log.Debugf("Copied %v bytes out of %v. err: %v stderr:%v", n, msg.Size, err, stderr)
+	return n, nil
+}
+
+func ack(writer io.Writer) error {
+	var msg = []byte{0, 0, 10, 13}
+	n, err := writer.Write(msg)
+	if err != nil {
+		return err
+	}
+	if n < len(msg) {
+		return errors.New("Failed to write ack buffer")
+	}
+	return nil
+}
+
+func copyN(writer io.Writer, src io.Reader, size int64) (int64, error) {
+	reader := io.LimitReader(src, size)
+	var total int64
+	for total < size {
+		n, err := io.CopyBuffer(writer, reader, make([]byte, buffSize))
+		log.Debugf("Copied chunk %v total: %v out of %v err: %v ", n, total, size, err)
+		if err != nil {
+			return 0, err
+		}
+		total += n
+	}
+	return total, nil
+}