From 975710f1451df0139ec444e471d384ca34361d97 Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Sat, 1 Nov 2025 10:23:41 +0100
Subject: [PATCH] remote: guard against (very unlikely) truncation when reading
 symlink target

---
 remote/sync/files.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/remote/sync/files.go b/remote/sync/files.go
index 3f0f196..4ccca5d 100644
--- a/remote/sync/files.go
+++ b/remote/sync/files.go
@@ -264,10 +264,16 @@ reopen:
 			}
 			oldData = x
 		case fs.ModeSymlink:
-			buf := make([]byte, unix.PathMax)
+			buf := make([]byte, unix.PathMax+1)
 			n, err := unix.Readlinkat(parentFd, baseName, buf)
 			if err != nil {
-				return fmt.Errorf("reading old content: %v", err)
+				return fmt.Errorf("reading old target: %v", err)
+			}
+			if n == len(buf) {
+				// Cannot differentiate between exact match and truncation.
+				// This shouldn't occur with unix.PathMax but let's be
+				// careful.
+				return fmt.Errorf("old path possibly truncated")
 			}
 			oldData = buf[:n]
 		}
-- 
2.51.2