master: Don't unlink login sockets at startup if someone is listening…

… to them.

The original check there never worked, because null_fd was always set.

Normally the master.pid file would prevent this happening, but if it didn't
exist, the sockets would be unlinked and usually also created back.

src/master/common.h

@@ -11,6 +11,7 @@ extern bool core_dumps_disabled;
 extern const char *ssl_manual_key_password;
 extern int null_fd, global_master_dead_pipe_fd[2];
 extern struct service_list *services;
+extern bool startup_finished;
 
 void process_exec(const char *cmd, const char *extra_args[])
 	ATTR_NORETURN ATTR_NULL(2);

src/master/main.c

@@ -45,6 +45,7 @@ bool core_dumps_disabled;
 const char *ssl_manual_key_password;
 int null_fd, global_master_dead_pipe_fd[2];
 struct service_list *services;
+bool startup_finished = FALSE;
 
 static char *pidfile_path;
 static struct master_instance_list *instances;
@@ -530,6 +531,7 @@ static void main_init(const struct master_settings *set)
 	master_clients_init();
 
 	services_monitor_start(services);
+	startup_finished = TRUE;
 }
 
 static void global_dead_pipe_close(void)

src/master/master-settings.c

@@ -721,8 +721,8 @@ static void unlink_sockets(const char *path, const char *prefix)
 		   listening in them. do this only at startup, because
 		   when SIGHUPing a child process might catch the new
 		   connection before it notices that it's supposed
-		   to die. null_fd == -1 check is a bit kludgy, but works.. */
-		if (null_fd == -1) {
+		   to die. */
+		if (!startup_finished) {
 			int fd = net_connect_unix(str_c(str));
 			if (fd != -1 || errno != ECONNREFUSED) {
 				i_fatal("Dovecot is already running? "