Index: dist/util.c
===================================================================
RCS file: /cvsroot/src/external/bsd/pam-u2f/dist/util.c,v
retrieving revision 1.4
diff -u -r1.4 util.c
--- dist/util.c	24 Sep 2021 13:08:16 -0000	1.4
+++ dist/util.c	20 Aug 2022 10:50:52 -0000
@@ -1306,6 +1306,27 @@
   return ok;
 }
 
+#ifndef WITH_FUZZING
+static FILE *log_handler_debug_file;
+static void log_handler(const char *str)
+{
+	size_t n = strlen(str);
+
+	/* remove linefeed */
+	if (n > 0 && str[n-1] == '\n')
+		--n;
+
+	/*
+	 * Field width can only be an int,
+	 * but printing more than INT_MAX ??
+	 */
+	if (n > INT_MAX)
+		return;
+
+	D(log_handler_debug_file, "%.*s", (int)n, str);
+}
+#endif
+
 int do_authentication(const cfg_t *cfg, const device_t *devices,
                       const unsigned n_devs, pam_handle_t *pamh) {
   fido_assert_t *assert = NULL;
@@ -1323,7 +1344,12 @@
 
   init_opts(&opts);
 #ifndef WITH_FUZZING
-  fido_init(cfg->debug ? FIDO_DEBUG : 0);
+  if (cfg->debug) {
+  	fido_init(FIDO_DEBUG);
+	log_handler_debug_file = cfg->debug_file;
+	fido_set_log_handler(log_handler);
+  } else
+  	fido_init(0);
 #else
   fido_init(0);
 #endif
@@ -1590,7 +1616,12 @@
 	goto out;
 
 #ifndef WITH_FUZZING
-  fido_init(cfg->debug ? FIDO_DEBUG : 0);
+  if (cfg->debug) {
+  	fido_init(FIDO_DEBUG);
+	log_handler_debug_file = cfg->debug_file;
+	fido_set_log_handler(log_handler);
+  } else
+  	fido_init(0);
 #else
   fido_init(0);
 #endif