Preserve modtime on copy so subsequent syncs don't re-copy everything

1 files changed, 11 insertions, 2 deletions

diff --git a/sync.go b/sync.go
index 78f3fa8..a22e628 100644
--- a/sync.go
+++ b/sync.go
@@ -141,6 +141,15 @@ func copyFile(src, dst string, mode os.FileMode) error {
 	}
 	defer dstFile.Close()
 
-	_, err = io.Copy(dstFile, srcFile)
-	return err
+	if _, err = io.Copy(dstFile, srcFile); err != nil {
+		return err
+	}
+
+	// Preserve modtime so next sync comparison matches
+	srcInfo, err := os.Lstat(src)
+	if err != nil {
+		return nil // content copied, modtime is non-fatal
+	}
+	os.Chtimes(dst, srcInfo.ModTime(), srcInfo.ModTime())
+	return nil
 }