From 33cc2c8bc3f81615b348e5d3b0945887b365168a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Fauberteau?= <frederic@fauberteau.org>
Date: Fri, 2 Jan 2026 13:11:02 +0100
Subject: [PATCH] Fix abort with ctype(3) on NetBSD 11

In NetBSD 11, the ctype functions will crash with a signal on certain
invalid inputs as a diagnostic aid for applications.

NetBSD defines tolower(3) with CTYPE_CHECK() that verifies that (c < 0
|| c > UCHAR_MAX). In the case of mp4v2::impl::MP4NameFirstMatches, it
aborts when s1 is "\251nam".
---
 src/mp4util.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mp4util.cpp b/src/mp4util.cpp
index 8a915b2..4212f3e 100644
--- a/src/mp4util.cpp
+++ b/src/mp4util.cpp
@@ -40,7 +40,7 @@ bool MP4NameFirstMatches(const char* s1, const char* s2)
         if (*s2 == '\0' || strchr("[.", *s2)) {
             break;
         }
-        if (tolower(*s1) != tolower(*s2)) {
+        if (tolower((unsigned char)*s1) != tolower((unsigned char)*s2)) {
             return false;
         }
         s1++;