From 85aabe233ec17b25b65d547e59b9a7f5d2e8479b Mon Sep 17 00:00:00 2001
From: Liu Hua <weldonliu@tencent.com>
Date: Thu, 13 May 2021 11:42:53 +0800
Subject: [PATCH] C/R: let criu use its default if --work-path is not set

Now runc puts dump/restore logs in c.root defaultly, which will be deleted
when container exits. So if checkpinting/restoring failed, we can not get
these logs and analyze why.

This patch lets criu use its default if --work-path is not set:
 - Use WorkDirectory found in criu's configfile.
 - Use ImageDirectory.

Signed-off-by: Liu Hua <weldonliu@tencent.com>
---
 libcontainer/container_linux.go | 55 ++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 29 deletions(-)

diff --git a/libcontainer/container_linux.go b/libcontainer/container_linux.go
index 6ce1854f6..7409f6f88 100644
--- a/libcontainer/container_linux.go
+++ b/libcontainer/container_linux.go
@@ -972,20 +972,6 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 		return err
 	}
 
-	if criuOpts.WorkDirectory == "" {
-		criuOpts.WorkDirectory = filepath.Join(c.root, "criu.work")
-	}
-
-	if err := os.Mkdir(criuOpts.WorkDirectory, 0o700); err != nil && !os.IsExist(err) {
-		return err
-	}
-
-	workDir, err := os.Open(criuOpts.WorkDirectory)
-	if err != nil {
-		return err
-	}
-	defer workDir.Close()
-
 	imageDir, err := os.Open(criuOpts.ImagesDirectory)
 	if err != nil {
 		return err
@@ -994,7 +980,6 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 
 	rpcOpts := criurpc.CriuOpts{
 		ImagesDirFd:     proto.Int32(int32(imageDir.Fd())),
-		WorkDirFd:       proto.Int32(int32(workDir.Fd())),
 		LogLevel:        proto.Int32(4),
 		LogFile:         proto.String("dump.log"),
 		Root:            proto.String(c.config.Rootfs),
@@ -1012,6 +997,19 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 		LazyPages:       proto.Bool(criuOpts.LazyPages),
 	}
 
+	// if criuOpts.WorkDirectory is not set, criu default is used.
+	if criuOpts.WorkDirectory != "" {
+		if err := os.Mkdir(criuOpts.WorkDirectory, 0o700); err != nil && !os.IsExist(err) {
+			return err
+		}
+		workDir, err := os.Open(criuOpts.WorkDirectory)
+		if err != nil {
+			return err
+		}
+		defer workDir.Close()
+		rpcOpts.WorkDirFd = proto.Int32(int32(workDir.Fd()))
+	}
+
 	c.handleCriuConfigurationFile(&rpcOpts)
 
 	// If the container is running in a network namespace and has
@@ -1311,19 +1309,6 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 	if err := c.checkCriuVersion(30000); err != nil {
 		return err
 	}
-	if criuOpts.WorkDirectory == "" {
-		criuOpts.WorkDirectory = filepath.Join(c.root, "criu.work")
-	}
-	// Since a container can be C/R'ed multiple times,
-	// the work directory may already exist.
-	if err := os.Mkdir(criuOpts.WorkDirectory, 0o700); err != nil && !os.IsExist(err) {
-		return err
-	}
-	workDir, err := os.Open(criuOpts.WorkDirectory)
-	if err != nil {
-		return err
-	}
-	defer workDir.Close()
 	if criuOpts.ImagesDirectory == "" {
 		return errors.New("invalid directory to restore checkpoint")
 	}
@@ -1356,7 +1341,6 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 		Type: &t,
 		Opts: &criurpc.CriuOpts{
 			ImagesDirFd:     proto.Int32(int32(imageDir.Fd())),
-			WorkDirFd:       proto.Int32(int32(workDir.Fd())),
 			EvasiveDevices:  proto.Bool(true),
 			LogLevel:        proto.Int32(4),
 			LogFile:         proto.String("restore.log"),
@@ -1384,6 +1368,19 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 		req.Opts.LsmProfile = proto.String(criuOpts.LsmProfile)
 	}
 
+	if criuOpts.WorkDirectory != "" {
+		// Since a container can be C/R'ed multiple times,
+		// the work directory may already exist.
+		if err := os.Mkdir(criuOpts.WorkDirectory, 0o700); err != nil && !os.IsExist(err) {
+			return err
+		}
+		workDir, err := os.Open(criuOpts.WorkDirectory)
+		if err != nil {
+			return err
+		}
+		defer workDir.Close()
+		req.Opts.WorkDirFd = proto.Int32(int32(workDir.Fd()))
+	}
 	c.handleCriuConfigurationFile(req.Opts)
 
 	if err := c.handleRestoringNamespaces(req.Opts, &extraFiles); err != nil {