From 54adc7ddd5918f6430c5712102176b7c6ca9f424 Mon Sep 17 00:00:00 2001
From: Avi Deitcher <avi@deitcher.net>
Date: Fri, 27 Jun 2025 10:07:42 +0300
Subject: [PATCH] ensure that new index does not break on missing lock file

Signed-off-by: Avi Deitcher <avi@deitcher.net>
---
 src/cmd/linuxkit/cache/open.go | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/cmd/linuxkit/cache/open.go b/src/cmd/linuxkit/cache/open.go
index d0d20c5fd..7c2025398 100644
--- a/src/cmd/linuxkit/cache/open.go
+++ b/src/cmd/linuxkit/cache/open.go
@@ -2,6 +2,7 @@ package cache
 
 import (
 	"fmt"
+	"os"
 	"path/filepath"
 
 	"github.com/google/go-containerregistry/pkg/v1/empty"
@@ -10,19 +11,29 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+var (
+	newIndexLockFile = filepath.Join(os.TempDir(), "linuxkit-new-cache-index.lock")
+)
+
 // Get get or initialize the cache
 func Get(cache string) (layout.Path, error) {
 	// initialize the cache path if needed
 	p, err := layout.FromPath(cache)
 	if err != nil {
-		lock, err := util.Lock(filepath.Join(cache, indexFile))
+		if err := os.WriteFile(newIndexLockFile, []byte{}, 0644); err != nil {
+			return "", fmt.Errorf("unable to create lock file %s for writing descriptor for new cache %s: %v", newIndexLockFile, cache, err)
+		}
+		lock, err := util.Lock(newIndexLockFile)
 		if err != nil {
-			return "", fmt.Errorf("unable to lock cache index for writing descriptor for new cache: %v", err)
+			return "", fmt.Errorf("unable to retrieve lock for writing descriptor for new cache %s: %v", newIndexLockFile, err)
 		}
 		defer func() {
 			if err := lock.Unlock(); err != nil {
 				log.Errorf("unable to close lock for cache index after writing descriptor for new cache: %v", err)
 			}
+			if err := os.RemoveAll(newIndexLockFile); err != nil {
+				log.Errorf("unable to remove lock file %s after writing descriptor for new cache: %v", newIndexLockFile, err)
+			}
 		}()
 		p, err = layout.Write(cache, empty.Index)
 		if err != nil {