--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/fitz/track-usage.c	Mon Sep 15 11:44:09 2025 +0200
@@ -0,0 +1,56 @@
+// Copyright (C) 2004-2021 Artifex Software, Inc.
+//
+// This file is part of MuPDF.
+//
+// MuPDF is free software: you can redistribute it and/or modify it under the
+// terms of the GNU Affero General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
+//
+// Alternative licensing terms are available from the licensor.
+// For commercial licensing, see <https://www.artifex.com/> or contact
+// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
+// CA 94129, USA, for further information.
+
+#include "mupdf/fitz.h"
+
+#ifdef TRACK_USAGE
+
+static track_usage_data_t *usage_head = NULL;
+
+static void dump_usage(void)
+{
+	track_usage_data_t *u = usage_head;
+
+	while (u)
+	{
+		fprintf(stderr, "USAGE: %s (%s:%d) %d calls\n",
+			u->desc, u->function, u->line, u->count);
+		u = u->next;
+	}
+}
+
+void track_usage(track_usage_data_t *data, const char *function, int line, const char *desc)
+{
+	int c = data->count++;
+	if (c == 0)
+	{
+		data->function = function;
+		data->line = line;
+		data->desc = desc;
+		if (usage_head == NULL)
+			atexit(dump_usage);
+		data->next = usage_head;
+		usage_head = data;
+	}
+}
+
+#endif