bbs: Ignore SIGHUP signal and don't skip logging if daemonized. (#47)

When running as a daemon, the BBS receives a SIGHUP whenever a remote
sysop console disconnects. Without handling the signal, this causes
the BBS to get killed by the kernel. To avoid this, install a dummy
signal handler when daemonized to ignore the signal and continue
running.

Additionally, logger.c was using the wrong check to determine whether
to generate a log message for outputting to terminals, which resulted
in no log messages on consoles when the BBS was daemonized. Adjust
this logic so that console messages are generated when needed.

Resolves: #46

bbs/bbs.c

@@ -670,6 +670,13 @@ static void __sigint_handler(int num)
 	}
 }
 
+static void __sighup_handler(int num)
+{
+	UNUSED(num);
+
+	bbs_debug(2, "Got SIGHUP, ignoring\n"); /* XXX technically not safe to use in signal handler */
+}
+
 /*! \brief Log any SIGWINCHes received */
 static void __sigwinch_handler(int num)
 {
@@ -711,6 +718,7 @@ static void __sigwinch_handler(int num)
 static void __sigusr1_handler(int num)
 {
 	UNUSED(num);
+
 	/* By default, if we use pthread_kill to try to send SIGUSR1 to a thread,
 	 * it will terminate the entire BBS.
 	 * Installing this dummy signal handler that does nothing prevents that,
@@ -986,6 +994,14 @@ int main(int argc, char *argv[])
 	}
 	signal(SIGINT, __sigint_handler);
 	signal(SIGTERM, __sigint_handler);
+	if (!option_nofork) {
+		/* If daemonized, we get a SIGHUP whenever a remote sysop console disconnects... ignore it,
+		 * or the BBS will get killed by the signal.
+		 * Frequently used by daemonized processes to reread their configuration,
+		 * for now we just ignore it.
+		 * If running in the foreground, then allow SIGHUP to terminate as usual. */
+		signal(SIGHUP, __sighup_handler);
+	}
 	signal(SIGWINCH, __sigwinch_handler);
 	signal(SIGUSR1, __sigusr1_handler);
 	sigaction(SIGPIPE, &ignore_sig_handler, NULL);

bbs/logger.c

@@ -180,6 +180,7 @@ static RWLIST_HEAD_STATIC(remote_log_fds, remote_log_fd);
 
 /*! \note Assumes all remote consoles are going to use a fd within the first 1024 */
 static int fd_logging[1024]; /* Array for constant time access instead of a linked list. Even though we traverse the list for writing, to set logging on/off, we don't need to. */
+static int active_remote_consoles = 0;
 
 int bbs_set_fd_logging(int fd, int enabled)
 {
@@ -254,6 +255,7 @@ int bbs_add_logging_fd(int fd)
 	rfd->maxdebug = MAX_DEBUG; /* By default, there is no local restriction on the max debug level */
 	RWLIST_INSERT_HEAD(&remote_log_fds, rfd, entry);
 	fd_logging[fd] = 1; /* Initialize to enabled */
+	active_remote_consoles++;
 	RWLIST_UNLOCK(&remote_log_fds);
 	bbs_debug(5, "Registered file descriptor %d for logging\n", fd);
 	return 0;
@@ -263,7 +265,10 @@ int bbs_remove_logging_fd(int fd)
 {
 	struct remote_log_fd *rfd;
 
-	rfd = RWLIST_WRLOCK_REMOVE_BY_FIELD(&remote_log_fds, fd, fd, entry);
+	RWLIST_WRLOCK(&remote_log_fds);
+	rfd = RWLIST_REMOVE_BY_FIELD(&remote_log_fds, fd, fd, entry);
+	active_remote_consoles--;
+	RWLIST_UNLOCK(&remote_log_fds);
 	if (unlikely(!rfd)) {
 		bbs_error("File descriptor %d did not have logging\n", fd);
 	} else {
@@ -389,7 +394,7 @@ void __attribute__ ((format (gnu_printf, 6, 7))) __bbs_log(enum bbs_log_level lo
 	int thread_id;
 	int dynamic = 0, fulldynamic = 0;
 	int bytes;
-	int log_stdout;
+	int log_stdout, log_remote;
 	int need_reset = 0;
 	int skip_logfile = 0;
 
@@ -484,8 +489,10 @@ void __attribute__ ((format (gnu_printf, 6, 7))) __bbs_log(enum bbs_log_level lo
 
 	/* Race condition here is fine, but helgrind won't like it: */
 	log_stdout = logstdout;
+	log_remote = active_remote_consoles > 0; /* Small chance a brand new console could register between this check and traversing the remote consoles... but not a big deal. */
 
-	if (log_stdout) {
+	/* If the foreground or any remote consoles are active, prepare a log message for any connected consoles. */
+	if (log_stdout || log_remote) {
 		struct remote_log_fd *rfd;
 		if (loglevel == LOG_VERBOSE && verbose_special_formatting) {
 			const char *verbprefix = verbose_prefix(level);
@@ -517,7 +524,12 @@ void __attribute__ ((format (gnu_printf, 6, 7))) __bbs_log(enum bbs_log_level lo
 			}
 		}
 
-		term_puts(fullbuf);
+		/* Log to foreground console, if there is one */
+		if (log_stdout) {
+			term_puts(fullbuf);
+		}
+
+		/* Log to remote consoles */
 		RWLIST_RDLOCK(&remote_log_fds);
 		RWLIST_TRAVERSE(&remote_log_fds, rfd, entry) {
 			if (loglevel == LOG_DEBUG && level > rfd->maxdebug) {