flowtop: Don't init screen until collector is ready

In case if main thread already initialized screen but then collector
called panic, the process exits but console stays with the same colored
screen and shifted shell prompt.

Fixed by adding conditional variable locking.

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

2 files changed, 40 insertions, 0 deletions

diff --git a/flowtop.c b/flowtop.c
index 2db5772..33a110c 100644
--- a/flowtop.c
+++ b/flowtop.c
@@ -80,6 +80,7 @@ struct flow_list {
 static volatile sig_atomic_t sigint = 0;
 static int what = INCLUDE_IPV4 | INCLUDE_IPV6 | INCLUDE_TCP, show_src = 0;
 static struct flow_list flow_list;
+static struct condlock collector_ready;
 
 static const char *short_options = "vhTUsDIS46u";
 static const struct option long_options[] = {
@@ -978,6 +979,8 @@ static void presenter(void)
 	int skip_lines = 0;
 	WINDOW *screen;
 
+	condlock_wait(&collector_ready);
+
 	lookup_init_ports(PORTS_TCP);
 	lookup_init_ports(PORTS_UDP);
 	screen = screen_init(false);
@@ -1104,6 +1107,8 @@ static void *collector(void *null __maybe_unused)
 	nfct_filter_destroy(filter);
 	flow_list_init(&flow_list);
 
+	condlock_signal(&collector_ready);
+
 	rcu_register_thread();
 
 	while (!sigint && ret >= 0)
@@ -1179,12 +1184,16 @@ int main(int argc, char **argv)
 
 	init_geoip(1);
 
+	condlock_init(&collector_ready);
+
 	ret = pthread_create(&tid, NULL, collector, NULL);
 	if (ret < 0)
 		panic("Cannot create phthread!\n");
 
 	presenter();
 
+	condlock_destroy(&collector_ready);
+
 	destroy_geoip();
 
 	return 0;
diff --git a/locking.h b/locking.h
index 51034b3..cb57a9d 100644
--- a/locking.h
+++ b/locking.h
@@ -15,6 +15,11 @@ struct rwlock {
 	pthread_rwlock_t lock;
 };
 
+struct condlock {
+	pthread_mutex_t lock;
+	pthread_cond_t cond;
+};
+
 static inline int spinlock_init(struct spinlock *l)
 {
 	return -pthread_spin_init(&l->lock, 0);
@@ -86,4 +91,30 @@ static inline void rwlock_unlock(struct rwlock *l)
 	pthread_rwlock_unlock(&l->lock);
 }
 
+static inline void condlock_init(struct condlock *c)
+{
+	pthread_mutex_init(&c->lock, NULL);
+	pthread_cond_init(&c->cond, NULL);
+}
+
+static inline void condlock_signal(struct condlock *c)
+{
+	pthread_mutex_lock(&c->lock);
+	pthread_cond_signal(&c->cond);
+	pthread_mutex_unlock(&c->lock);
+}
+
+static inline void condlock_wait(struct condlock *c)
+{
+	pthread_mutex_lock(&c->lock);
+	pthread_cond_wait(&c->cond, &c->lock);
+	pthread_mutex_unlock(&c->lock);
+}
+
+static inline void condlock_destroy(struct condlock *c)
+{
+	pthread_mutex_destroy(&c->lock);
+	pthread_cond_destroy(&c->cond);
+}
+
 #endif /* LOCKING_H */