From 4cda859eb8001342be30e46fdf2d9df7e39a5ee2 Mon Sep 17 00:00:00 2001
From: "Dirk-Jan C. Binnema" <djcb@djcbsoftware.nl>
Date: Sun, 23 Mar 2025 17:09:03 +0200
Subject: [PATCH] mu-sexp: tighten definition of plistp

In a plist, we also require the first of each two element pairs to start
with ':'

Fixes #2830.
---
 lib/utils/mu-sexp.cc | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/utils/mu-sexp.cc b/lib/utils/mu-sexp.cc
index 8434f986..6a173b7c 100644
--- a/lib/utils/mu-sexp.cc
+++ b/lib/utils/mu-sexp.cc
@@ -326,7 +326,9 @@ Sexp::plistp(Sexp::const_iterator b, Sexp::const_iterator e) const
 	else if (b + 1 == e)
 		return false;
 	else
-		return b->symbolp() && plistp(b + 2, e);
+		return b->symbolp() &&
+			b->symbol().name.starts_with(':')
+			&& plistp(b + 2, e);
 }