Use jack_on_shutdown callback to terminate gracefully when Jack is shutting down.

jackdriver.c

@@ -369,6 +369,15 @@ int pop_midi(void* seqq, uint8_t msg[], uint8_t *port_no)
   return 0;
 }
 
+int jack_shutdown;
+
+void
+shutdown_callback()
+{
+  // we can't do anything fancy here, just ping the main thread
+  jack_shutdown = 1;
+}
+
 ////////////////////////////////
 //this is run in the main thread
 ////////////////////////////////
@@ -388,6 +397,9 @@ init_jack(JACK_SEQ* seq, uint8_t verbose)
       return 0;
     }
 
+    if(verbose)printf("assigning shutdown callback...\n");
+    jack_on_shutdown(seq->jack_client, shutdown_callback, (void*)seq);
+
     if(verbose)printf("assigning process callback...\n");
     err = jack_set_process_callback(seq->jack_client, process_callback, (void*)seq);
     if (err)

jackdriver.h

@@ -15,6 +15,8 @@ typedef struct _jseq
   uint8_t n_out;
 } JACK_SEQ;
 
+extern int jack_shutdown;
+
 int init_jack(JACK_SEQ* seq, uint8_t verbose);
 void close_jack(JACK_SEQ* seq);
 void queue_midi(void* seqq, uint8_t msg[], uint8_t port_no);

midizap.c

@@ -900,6 +900,11 @@ main(int argc, char **argv)
   signal(SIGINT, quitter);
   while (!quit) {
     uint8_t portno;
+    if (jack_shutdown) {
+      fprintf(stderr, "%s: jack shutting down, exiting\n", argv[0]);
+      close_jack(&seq);
+      exit(0);
+    }
     while (pop_midi(&seq, msg, &portno)) {
       handle_event(msg, portno);
       count = 0;