Server logs stack trace on SIGSEGV

Makefile.am

@@ -23,6 +23,7 @@ endif
 
 CFLAGS += -Wno-unused-parameter -Wno-unused-variable
 CFLAGS += -Ilibssh/include/ -Imsgpack/src
+CFLAGS += -rdynamic # for stack traces
 
 if IS_DEVENV
 CFLAGS += -DDEVENV

tmate-debug.c

@@ -59,8 +59,8 @@ void tmate_print_trace(void)
 	char **strings;
 	size_t i;
 
-	size = backtrace (array, 20);
-	strings = backtrace_symbols (array, size);
+	size = backtrace(array, 20);
+	strings = backtrace_symbols(array, size);
 
 	tmate_info("============ %zd stack frames ============", size);
 
@@ -71,5 +71,11 @@ void tmate_print_trace(void)
 			tmate_info("%s", strings[i]);
 	}
 
-	free (strings);
+	free(strings);
+}
+
+void tmate_preload_trace_lib(void)
+{
+	void *array[0];
+	backtrace(array, 0);
 }

tmate-slave.c

@@ -61,6 +61,8 @@ int main(int argc, char **argv)
 	    (mkdir(TMATE_WORKDIR "/jail", 0700)     < 0 && errno != EEXIST))
 		tmate_fatal("Cannot prepare session in " TMATE_WORKDIR);
 
+	tmate_preload_trace_lib();
+
 	tmate_ssh_server_main(port);
 	return 0;
 }

tmate-ssh-server.c

@@ -189,11 +189,18 @@ static void handle_sigalrm(void)
 	tmate_fatal("Connection grace period (%d) passed", SSH_GRACE_PERIOD);
 }
 
+static void handle_sigsegv(void)
+{
+	tmate_print_trace();
+	tmate_fatal("CRASH");
+}
+
 static void signal_handler(int sig)
 {
 	switch (sig) {
 	case SIGCHLD: handle_sigchld(); break;
 	case SIGALRM: handle_sigalrm(); break;
+	case SIGSEGV: handle_sigsegv(); break;
 	}
 }
 
@@ -201,6 +208,7 @@ static void setup_signals(void)
 {
 	signal(SIGCHLD, signal_handler);
 	signal(SIGALRM, signal_handler);
+	signal(SIGSEGV, signal_handler);
 }
 
 static void ssh_log_cb(ssh_session session, int priority,

tmate.h

@@ -137,6 +137,7 @@ extern const char *tmate_session_token;
 extern void tmate_spawn_slave(struct tmate_ssh_client *client);
 
 /* tmate-debug.c */
+extern void tmate_preload_trace_lib(void);
 extern void tmate_print_trace(void);
 
 /* tmux-bare.c */