From cf9359b3d76b2eb794af4c6d2161fac9d8c28e0e Mon Sep 17 00:00:00 2001
From: Mark Yen <mark.yen@suse.com>
Date: Thu, 2 Sep 2021 15:26:18 -0700
Subject: [PATCH 1/2] copy: use SSHArgs if copying to a single remote host.

This lets us use ControlPath with the connection, so that if a small number
of copies run in parallel we can reuse the connection, rather than failing
when too many connections are in flight.

Signed-off-by: Mark Yen <mark.yen@suse.com>
---
 cmd/limactl/copy.go    | 30 ++++++++++++++++++++++--------
 pkg/sshutil/sshutil.go |  2 +-
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/cmd/limactl/copy.go b/cmd/limactl/copy.go
index 07c7595282c..4c1a0d70d6d 100644
--- a/cmd/limactl/copy.go
+++ b/cmd/limactl/copy.go
@@ -36,12 +36,8 @@ func copyAction(clicontext *cli.Context) error {
 		return err
 	}
 
-	const useDotSSH = false
-	args, err := sshutil.CommonArgs(useDotSSH)
-	if err != nil {
-		return err
-	}
-	args = append(args, "-3", "--")
+	instDirs := make(map[string]string)
+	args := []string{"-3", "--"}
 	for _, arg := range clicontext.Args().Slice() {
 		path := strings.Split(arg, ":")
 		switch len(path) {
@@ -60,15 +56,33 @@ func copyAction(clicontext *cli.Context) error {
 				return fmt.Errorf("instance %q is stopped, run `limactl start %s` to start the instance", instName, instName)
 			}
 			args = append(args, fmt.Sprintf("scp://%s@127.0.0.1:%d/%s", u.Username, inst.SSHLocalPort, path[1]))
+			instDirs[instName] = inst.Dir
 		default:
 			return fmt.Errorf("Path %q contains multiple colons", arg)
 		}
 	}
-	cmd := exec.Command(arg0, args...)
+
+	sshArgs := []string{}
+	if len(instDirs) == 1 {
+		for _, instDir := range instDirs {
+			sshArgs, err = sshutil.SSHArgs(instDir, false)
+			if err != nil {
+				return err
+			}
+		}
+	} else {
+		// Copying among multiple hosts; we can't pass in host-specific options.
+		sshArgs, err = sshutil.CommonArgs(false)
+		if err != nil {
+			return err
+		}
+	}
+
+	cmd := exec.Command(arg0, append(sshArgs, args...)...)
 	cmd.Stdin = os.Stdin
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
-	logrus.Debugf("executing scp (may take a long)): %+v", cmd.Args)
+	logrus.Debugf("executing scp (may take a long time)): %+v", cmd.Args)
 
 	// TODO: use syscall.Exec directly (results in losing tty?)
 	return cmd.Run()
diff --git a/pkg/sshutil/sshutil.go b/pkg/sshutil/sshutil.go
index b57590aff1d..b37a4fd0a71 100644
--- a/pkg/sshutil/sshutil.go
+++ b/pkg/sshutil/sshutil.go
@@ -172,7 +172,7 @@ func SSHArgs(instDir string, useDotSSH bool) ([]string, error) {
 		return nil, err
 	}
 	args = append(args,
-		"-l", u.Username, // guest and host have the same username, but we should specify the username explicitly (#85)
+		"-o", fmt.Sprintf("User=%s", u.Username), // guest and host have the same username, but we should specify the username explicitly (#85)
 		"-o", "ControlMaster=auto",
 		"-o", fmt.Sprintf("ControlPath=\"%s\"", controlSock),
 		"-o", "ControlPersist=5m",

From 13d5197493798df84ef80e5fd155d828308cb573 Mon Sep 17 00:00:00 2001
From: Mark Yen <mark.yen@suse.com>
Date: Thu, 2 Sep 2021 16:54:02 -0700
Subject: [PATCH 2/2] Copy: Add comment on why we want to use instance-specific
 args.

https://github.com/lima-vm/lima/pull/194#pullrequestreview-745595685

Signed-off-by: Mark Yen <mark.yen@suse.com>
---
 cmd/limactl/copy.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/cmd/limactl/copy.go b/cmd/limactl/copy.go
index 4c1a0d70d6d..2967521fde9 100644
--- a/cmd/limactl/copy.go
+++ b/cmd/limactl/copy.go
@@ -64,6 +64,9 @@ func copyAction(clicontext *cli.Context) error {
 
 	sshArgs := []string{}
 	if len(instDirs) == 1 {
+		// Only one (instance) host is involved; we can use the instance-specific
+		// arguments such as ControlPath.  This is preferred as we can multiplex
+		// sessions without re-authenticating (MaxSessions permitting).
 		for _, instDir := range instDirs {
 			sshArgs, err = sshutil.SSHArgs(instDir, false)
 			if err != nil {