Initialize cwd fd to -1 so that we don't close fd 0 if the client is

destroyed before it is changed. Also allow ttyname() to fail. Fixes
problems when running out of file descriptors reported by Bruno Sutic.

server-client.c

@@ -96,6 +96,8 @@ server_client_create(int fd)
 
 	environ_init(&c->environ);
 
+	c->cwd = -1;
+
 	c->cmdq = cmdq_new(c);
 	c->cmdq->client_exit = 1;
 
@@ -1253,12 +1255,11 @@ server_client_msg_identify(struct client *c, struct imsg *imsg)
 
 	if (c->fd == -1)
 		return;
-	if (!isatty(c->fd)) {
+	if (tty_init(&c->tty, c, c->fd, c->term) != 0) {
 		close(c->fd);
 		c->fd = -1;
 		return;
 	}
-	tty_init(&c->tty, c, c->fd, c->term);
 	if (c->flags & CLIENT_UTF8)
 		c->tty.flags |= TTY_UTF8;
 	if (c->flags & CLIENT_256COLOURS)

tmux.h

@@ -1600,7 +1600,7 @@ void	tty_putcode_ptr2(struct tty *, enum tty_code_code, const void *,
 void	tty_puts(struct tty *, const char *);
 void	tty_putc(struct tty *, u_char);
 void	tty_putn(struct tty *, const void *, size_t, u_int);
-void	tty_init(struct tty *, struct client *, int, char *);
+int	tty_init(struct tty *, struct client *, int, char *);
 int	tty_resize(struct tty *);
 int	tty_set_size(struct tty *, u_int, u_int);
 void	tty_set_class(struct tty *, u_int);

tty.c

@@ -59,11 +59,14 @@ void	tty_default_colours(struct grid_cell *, const struct window_pane *);
 #define tty_pane_full_width(tty, ctx) \
 	((ctx)->xoff == 0 && screen_size_x((ctx)->wp->screen) >= (tty)->sx)
 
-void
+int
 tty_init(struct tty *tty, struct client *c, int fd, char *term)
 {
 	char	*path;
 
+	if (!isatty(fd))
+		return (-1);
+
 	memset(tty, 0, sizeof *tty);
 	tty->log_fd = -1;
 
@@ -75,13 +78,15 @@ tty_init(struct tty *tty, struct client *c, int fd, char *term)
 	tty->client = c;
 
 	if ((path = ttyname(fd)) == NULL)
-		fatalx("ttyname failed");
+		return (-1);
 	tty->path = xstrdup(path);
 	tty->cstyle = 0;
 	tty->ccolour = xstrdup("");
 
 	tty->flags = 0;
 	tty->term_flags = 0;
+
+	return (0);
 }
 
 int