From 7a3d6cf3f9106513befeebb4d92f6ca7558cb038 Mon Sep 17 00:00:00 2001
From: Nadav0077 <18245584+Nadav0077@users.noreply.github.com>
Date: Fri, 17 Apr 2026 23:19:51 +0300
Subject: [PATCH] accounts/keystore: fsync temp keyfile before rename

Without this, a crash or power loss between the write and the rename can leave the final UTC--... keyfile on disk with zero bytes, which permanently loses the newly generated key. Mirrors the fix in core/rawdb for freezer index files (573d94013).
---
 accounts/keystore/key.go | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/accounts/keystore/key.go b/accounts/keystore/key.go
index 9b2ac14712..6a554d831c 100644
--- a/accounts/keystore/key.go
+++ b/accounts/keystore/key.go
@@ -205,7 +205,18 @@ func writeTemporaryKeyFile(file string, content []byte) (string, error) {
 		os.Remove(f.Name())
 		return "", err
 	}
-	f.Close()
+	// Persist the contents to disk before the caller renames it into place,
+	// so that a crash or power loss between the write and the rename cannot
+	// leave a zero-length keyfile at the final path.
+	if err := f.Sync(); err != nil {
+		f.Close()
+		os.Remove(f.Name())
+		return "", err
+	}
+	if err := f.Close(); err != nil {
+		os.Remove(f.Name())
+		return "", err
+	}
 	return f.Name(), nil
 }