From 0559807783fd307c5b825b92653412e82b239c01 Mon Sep 17 00:00:00 2001
From: Jakob van Santen <jvansanten@gmail.com>
Date: Wed, 11 Feb 2026 17:46:08 +0100
Subject: [PATCH] Always write complete files in sidecar meta provider

Some filesystems like dCache don't allow file truncation
---
 backend/meta/sidecar.go | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/backend/meta/sidecar.go b/backend/meta/sidecar.go
index 1d6a6b4f..a713b115 100644
--- a/backend/meta/sidecar.go
+++ b/backend/meta/sidecar.go
@@ -75,11 +75,22 @@ func (s SideCar) StoreAttribute(_ *os.File, bucket, object, attribute string, va
 	}
 
 	attr := filepath.Join(metadir, attribute)
-	err = os.WriteFile(attr, value, 0666)
+	tempfile, err := os.CreateTemp(metadir, attribute)
+	if err != nil {
+		return fmt.Errorf("failed to create temporary file: %v", err)
+	}
+	defer os.Remove(tempfile.Name())
+	defer tempfile.Close()
+
+	_, err = tempfile.Write(value)
 	if err != nil {
 		return fmt.Errorf("failed to write attribute: %v", err)
 	}
 
+	err = os.Rename(tempfile.Name(), attr)
+	if err != nil {
+		return fmt.Errorf("failed to rename temporary file: %v", err)
+	}
 	return nil
 }