runc/patch/0131-runc-save-state-atomic.patch

From 957c155cdf03ef1b3bb53d1e107850924bda2c89 Mon Sep 17 00:00:00 2001
From: cenhuilin <cenhuilin@kylinos.cn>
Date: Fri, 8 Jul 2022 02:00:53 +0000
Subject: [PATCH] Write state.json atomically
We want to make sure that the state file is syned and cannot be
read partially or truncated.

Signed-off-by: Mrunal Patel <mrunalp@gmail.com>
---
 libcontainer/container_linux.go | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/libcontainer/container_linux.go b/libcontainer/container_linux.go
index 7be84a6..709a95e 100644
--- a/libcontainer/container_linux.go
+++ b/libcontainer/container_linux.go
@@ -1385,13 +1385,30 @@ func (c *linuxContainer) updateState(process parentProcess) (*State, error) {
 	return state, nil
 }
 
-func (c *linuxContainer) saveState(s *State) error {
-	f, err := os.Create(filepath.Join(c.root, stateFilename))
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-	return utils.WriteJSON(f, s)
+func (c *linuxContainer) saveState(s *State) (retErr error) {
+        tmpFile, err := ioutil.TempFile(c.root, "state-")
+        if err != nil {
+                return err
+        }
+
+        defer func() {
+                if retErr != nil {
+                        tmpFile.Close()
+                        os.Remove(tmpFile.Name())
+                }
+        }()
+
+        err = utils.WriteJSON(tmpFile, s)
+        if err != nil {
+                return err
+        }
+        err = tmpFile.Close()
+        if err != nil {
+                return err
+        }
+
+        stateFilePath := filepath.Join(c.root, stateFilename)
+        return os.Rename(tmpFile.Name(), stateFilePath)
 }
 
 func (c *linuxContainer) deleteState() error {
-- 
2.33.0