Treat plausible but invalid keys (like C-BSpace) as literal like any

other unrecognised string passed to send-keys. Reported by Anthony
Sottile in GitHub issue 2049.

cmd-send-keys.c

@@ -60,6 +60,9 @@ static struct cmdq_item *
 cmd_send_keys_inject_key(struct client *c, struct cmd_find_state *fs,
     struct cmdq_item *item, key_code key)
 {
+	struct session			*s = fs->s;
+	struct winlink			*wl = fs->wl;
+	struct window_pane		*wp = fs->wp;
 	struct window_mode_entry	*wme;
 	struct key_table		*table;
 	struct key_binding		*bd;
@@ -68,7 +71,8 @@ cmd_send_keys_inject_key(struct client *c, struct cmd_find_state *fs,
 	if (wme == NULL || wme->mode->key_table == NULL) {
 		if (options_get_number(fs->wp->window->options, "xterm-keys"))
 			key |= KEYC_XTERM;
-		window_pane_key(fs->wp, item->client, fs->s, fs->wl, key, NULL);
+		if (window_pane_key(wp, item->client, s, wl, key, NULL) != 0)
+			return (NULL);
 		return (item);
 	}
 	table = key_bindings_get_table(wme->mode->key_table(wme), 1);
@@ -87,6 +91,7 @@ cmd_send_keys_inject_string(struct client *c, struct cmd_find_state *fs,
     struct cmdq_item *item, struct args *args, int i)
 {
 	const char		*s = args->argv[i];
+	struct cmdq_item	*new_item;
 	struct utf8_data	*ud, *uc;
 	wchar_t			 wc;
 	key_code		 key;
@@ -104,8 +109,11 @@ cmd_send_keys_inject_string(struct client *c, struct cmd_find_state *fs,
 	literal = args_has(args, 'l');
 	if (!literal) {
 		key = key_string_lookup_string(s);
-		if (key != KEYC_NONE && key != KEYC_UNKNOWN)
+		if (key != KEYC_NONE && key != KEYC_UNKNOWN) {
-			return (cmd_send_keys_inject_key(c, fs, item, key));
+			new_item = cmd_send_keys_inject_key(c, fs, item, key);
+			if (new_item != NULL)
+				return (new_item);
+		}
 		literal = 1;
 	}
 	if (literal) {

input-keys.c

@@ -150,7 +150,7 @@ input_split2(u_int c, u_char *dst)
 }
 
 /* Translate a key code into an output key sequence. */
-void
+int
 input_key(struct window_pane *wp, key_code key, struct mouse_event *m)
 {
 	const struct input_key_ent	*ike;
@@ -167,14 +167,14 @@ input_key(struct window_pane *wp, key_code key, struct mouse_event *m)
 	if (KEYC_IS_MOUSE(key)) {
 		if (m != NULL && m->wp != -1 && (u_int)m->wp == wp->id)
 			input_key_mouse(wp, m);
-		return;
+		return (0);
 	}
 
 	/* Literal keys go as themselves (can't be more than eight bits). */
 	if (key & KEYC_LITERAL) {
 		ud.data[0] = (u_char)key;
 		bufferevent_write(wp->event, &ud.data[0], 1);
-		return;
+		return (0);
 	}
 
 	/* Is this backspace? */
@@ -195,15 +195,15 @@ input_key(struct window_pane *wp, key_code key, struct mouse_event *m)
 			bufferevent_write(wp->event, "\033", 1);
 		ud.data[0] = justkey;
 		bufferevent_write(wp->event, &ud.data[0], 1);
-		return;
+		return (0);
 	}
 	if (justkey > 0x7f && justkey < KEYC_BASE) {
 		if (utf8_split(justkey, &ud) != UTF8_DONE)
-			return;
+			return (-1);
 		if (key & KEYC_ESCAPE)
 			bufferevent_write(wp->event, "\033", 1);
 		bufferevent_write(wp->event, ud.data, ud.size);
-		return;
+		return (0);
 	}
 
 	/*
@@ -214,7 +214,7 @@ input_key(struct window_pane *wp, key_code key, struct mouse_event *m)
 		if ((out = xterm_keys_lookup(key)) != NULL) {
 			bufferevent_write(wp->event, out, strlen(out));
 			free(out);
-			return;
+			return (0);
 		}
 	}
 	key &= ~KEYC_XTERM;
@@ -237,7 +237,7 @@ input_key(struct window_pane *wp, key_code key, struct mouse_event *m)
 	}
 	if (i == nitems(input_keys)) {
 		log_debug("key 0x%llx missing", key);
-		return;
+		return (-1);
 	}
 	dlen = strlen(ike->data);
 	log_debug("found key 0x%llx: \"%s\"", key, ike->data);
@@ -246,6 +246,7 @@ input_key(struct window_pane *wp, key_code key, struct mouse_event *m)
 	if (key & KEYC_ESCAPE)
 		bufferevent_write(wp->event, "\033", 1);
 	bufferevent_write(wp->event, ike->data, dlen);
+	return (0);
 }
 
 /* Translate mouse and output. */

tmux.h

@@ -2275,7 +2275,7 @@ void	 input_parse(struct window_pane *);
 void	 input_parse_buffer(struct window_pane *, u_char *, size_t);
 
 /* input-key.c */
-void	 input_key(struct window_pane *, key_code, struct mouse_event *);
+int	 input_key(struct window_pane *, key_code, struct mouse_event *);
 
 /* xterm-keys.c */
 char	*xterm_keys_lookup(key_code);
@@ -2498,7 +2498,7 @@ int		 window_pane_set_mode(struct window_pane *,
 		     struct args *);
 void		 window_pane_reset_mode(struct window_pane *);
 void		 window_pane_reset_mode_all(struct window_pane *);
-void		 window_pane_key(struct window_pane *, struct client *,
+int		 window_pane_key(struct window_pane *, struct client *,
 		     struct session *, struct winlink *, key_code,
 		     struct mouse_event *);
 int		 window_pane_visible(struct window_pane *);

window.c

@@ -1229,7 +1229,7 @@ window_pane_reset_mode_all(struct window_pane *wp)
 		window_pane_reset_mode(wp);
 }
 
-void
+int
 window_pane_key(struct window_pane *wp, struct client *c, struct session *s,
     struct winlink *wl, key_code key, struct mouse_event *m)
 {
@@ -1237,23 +1237,24 @@ window_pane_key(struct window_pane *wp, struct client *c, struct session *s,
 	struct window_pane		*wp2;
 
 	if (KEYC_IS_MOUSE(key) && m == NULL)
-		return;
+		return (-1);
 
 	wme = TAILQ_FIRST(&wp->modes);
 	if (wme != NULL) {
 		wp->modelast = time(NULL);
 		if (wme->mode->key != NULL)
 			wme->mode->key(wme, c, s, wl, (key & ~KEYC_XTERM), m);
-		return;
+		return (0);
 	}
 
 	if (wp->fd == -1 || wp->flags & PANE_INPUTOFF)
-		return;
+		return (0);
 
-	input_key(wp, key, m);
+	if (input_key(wp, key, m) != 0)
+		return (-1);
 
 	if (KEYC_IS_MOUSE(key))
-		return;
+		return (0);
 	if (options_get_number(wp->window->options, "synchronize-panes")) {
 		TAILQ_FOREACH(wp2, &wp->window->panes, entry) {
 			if (wp2 != wp &&
@@ -1264,6 +1265,7 @@ window_pane_key(struct window_pane *wp, struct client *c, struct session *s,
 				input_key(wp2, key, NULL);
 		}
 	}
+	return (0);
 }
 
 int