Some improvements and bug fixes for hooks:

- Prepare the state again before the "after" hooks are run, because the
  command may have killed or moved windows.

- Use the hooks list from the newly prepared target, not the old hooks
  list (only matters for new-session really).

- Correctly detect an invalid current state and ignore it in
  cmd_find_target ("killw; swapw").

- Change neww, new, killp, killw, splitw, swapp, swapw to update the
  current state (used if no explicit target is given) to something more
  useful after they have finished. For example, neww changes it to the
  newly created window.

Hooks are still relatively new and primitive so there are likely to be
more changes to come.

Parts based on bug reports from Uwe Werler and Iblis Lin.

cmd-find.c

@@ -803,6 +803,15 @@ cmd_find_clear_state(struct cmd_find_state *fs, struct cmd_q *cmdq, int flags)
 	fs->idx = -1;
 }
 
+/* Check if state is empty/ */
+int
+cmd_find_empty_state(struct cmd_find_state *fs)
+{
+	if (fs->s == NULL && fs->wl == NULL && fs->w == NULL && fs->wp == NULL)
+		return (1);
+	return (0);
+}
+
 /* Check if a state if valid. */
 int
 cmd_find_valid_state(struct cmd_find_state *fs)
@@ -959,12 +968,19 @@ cmd_find_target(struct cmd_find_state *fs, struct cmd_find_state *current,
 	cmd_find_clear_state(fs, cmdq, flags);
 
 	/* Find current state. */
-	if (server_check_marked() && (flags & CMD_FIND_DEFAULT_MARKED))
+	if (server_check_marked() && (flags & CMD_FIND_DEFAULT_MARKED)) {
 		fs->current = &marked_pane;
-	else if (cmd_find_valid_state(&cmdq->current))
+		log_debug("    current is marked pane");
+	} else if (cmd_find_valid_state(&cmdq->current)) {
 		fs->current = &cmdq->current;
-	else
+		log_debug("    current is from queue");
+	} else {
 		fs->current = current;
+		log_debug("    current is from argument");
+	}
+	if (!cmd_find_empty_state(fs->current) &&
+	    !cmd_find_valid_state(fs->current))
+		fatalx("invalid current find state");
 
 	/* An empty or NULL target is the current. */
 	if (target == NULL || *target == '\0')

cmd-join-pane.c

@@ -156,5 +156,12 @@ cmd_join_pane_exec(struct cmd *self, struct cmd_q *cmdq)
 		notify_window_layout_changed(src_w);
 	notify_window_layout_changed(dst_w);
 
+	cmd_find_clear_state(&cmdq->current, NULL, 0);
+	cmdq->current.s = dst_s;
+	cmdq->current.wl = dst_wl;
+	cmdq->current.w = dst_w;
+	cmdq->current.wp = dst_wp;
+	cmd_find_log_state(__func__, &cmdq->current);
+
 	return (CMD_RETURN_NORMAL);
 }

cmd-new-session.c

@@ -310,6 +310,8 @@ cmd_new_session_exec(struct cmd *self, struct cmd_q *cmdq)
 		format_free(ft);
 	}
 
+	cmd_find_from_session(&cmdq->current, s);
+
 	if (!detached)
 		cmdq->client_exit = 0;
 

cmd-new-window.c

@@ -152,6 +152,8 @@ cmd_new_window_exec(struct cmd *self, struct cmd_q *cmdq)
 		format_free(ft);
 	}
 
+	cmd_find_from_winlink(&cmdq->current, s, wl);
+
 	if (to_free != NULL)
 		free((void *)to_free);
 	return (CMD_RETURN_NORMAL);

cmd-queue.c

@@ -182,13 +182,30 @@ cmdq_append(struct cmd_q *cmdq, struct cmd_list *cmdlist, struct mouse_event *m)
 		item->mouse.valid = 0;
 }
 
+/* Find hooks list. */
+static struct hooks *
+cmdq_get_hooks(struct cmd_q *cmdq)
+{
+	struct session	*s;
+
+	s = NULL;
+	if (cmdq->state.tflag.s != NULL)
+		s = cmdq->state.tflag.s;
+	else if (cmdq->state.sflag.s != NULL)
+		s = cmdq->state.sflag.s;
+	else if (cmdq->state.c != NULL)
+		s = cmdq->state.c->session;
+	if (s != NULL)
+		return (s->hooks);
+	return (global_hooks);
+}
+
 /* Process one command. */
 static enum cmd_retval
 cmdq_continue_one(struct cmd_q *cmdq)
 {
 	struct cmd	*cmd = cmdq->cmd;
 	const char	*name = cmd->entry->name;
-	struct session	*s;
 	struct hooks	*hooks;
 	enum cmd_retval	 retval;
 	char		*tmp;
@@ -208,18 +225,7 @@ cmdq_continue_one(struct cmd_q *cmdq)
 		goto error;
 
 	if (~cmdq->flags & CMD_Q_NOHOOKS) {
-		s = NULL;
-		if (cmdq->state.tflag.s != NULL)
-			s = cmdq->state.tflag.s;
-		else if (cmdq->state.sflag.s != NULL)
-			s = cmdq->state.sflag.s;
-		else if (cmdq->state.c != NULL)
-			s = cmdq->state.c->session;
-		if (s != NULL)
-			hooks = s->hooks;
-		else
-			hooks = global_hooks;
-
+		hooks = cmdq_get_hooks(cmdq);
 		if (~cmdq->flags & CMD_Q_REENTRY) {
 			cmdq->flags |= CMD_Q_REENTRY;
 			if (hooks_wait(hooks, cmdq, NULL,
@@ -236,9 +242,13 @@ cmdq_continue_one(struct cmd_q *cmdq)
 	if (retval == CMD_RETURN_ERROR)
 		goto error;
 
-	if (hooks != NULL && hooks_wait(hooks, cmdq, NULL,
-	    "after-%s", name) == 0)
-		retval = CMD_RETURN_WAIT;
+	if (hooks != NULL) {
+		if (cmd_prepare_state(cmd, cmdq, cmdq->parent) != 0)
+			goto error;
+		hooks = cmdq_get_hooks(cmdq);
+		if (hooks_wait(hooks, cmdq, NULL, "after-%s", name) == 0)
+			retval = CMD_RETURN_WAIT;
+	}
 	cmdq_guard(cmdq, "end", flags);
 
 	return (retval);
@@ -261,6 +271,8 @@ cmdq_continue(struct cmd_q *cmdq)
 	cmdq->references++;
 	notify_disable();
 
+	cmd_find_clear_state(&cmdq->current, NULL, 0);
+
 	log_debug("continuing cmdq %p: flags %#x, client %p", cmdq, cmdq->flags,
 	    c);
 

cmd-split-window.c

@@ -178,6 +178,13 @@ cmd_split_window_exec(struct cmd *self, struct cmd_q *cmdq)
 	}
 	notify_window_layout_changed(w);
 
+	cmd_find_clear_state(&cmdq->current, NULL, 0);
+	cmdq->current.s = s;
+	cmdq->current.wl = wl;
+	cmdq->current.w = wl->window;
+	cmdq->current.wp = new_wp;
+	cmd_find_log_state(__func__, &cmdq->current);
+
 	if (to_free != NULL)
 		free((void *)to_free);
 	return (CMD_RETURN_NORMAL);

cmd-swap-pane.c

@@ -124,5 +124,12 @@ cmd_swap_pane_exec(struct cmd *self, struct cmd_q *cmdq)
 	server_redraw_window(src_w);
 	server_redraw_window(dst_w);
 
+	cmd_find_clear_state(&cmdq->current, NULL, 0);
+	cmdq->current.s = cmdq->state.tflag.s;
+	cmdq->current.wl = cmdq->state.tflag.wl;
+	cmdq->current.w = dst_w;
+	cmdq->current.wp = src_wp;
+	cmd_find_log_state(__func__, &cmdq->current);
+
 	return (CMD_RETURN_NORMAL);
 }

cmd-swap-window.c

@@ -84,5 +84,12 @@ cmd_swap_window_exec(struct cmd *self, struct cmd_q *cmdq)
 	}
 	recalculate_sizes();
 
+	cmd_find_clear_state(&cmdq->current, NULL, 0);
+	cmdq->current.s = dst;
+	cmdq->current.wl = wl_dst;
+	cmdq->current.w = wl_dst->window;
+	cmdq->current.wp = cmdq->state.sflag.wp;
+	cmd_find_log_state(__func__, &cmdq->current);
+
 	return (CMD_RETURN_NORMAL);
 }

cmd.c

@@ -456,12 +456,15 @@ cmd_prepare_state_flag(char c, const char *target, enum cmd_entry_flag flag,
 			current = &parent->state.tflag;
 		else if (c == 's')
 			current = &parent->state.sflag;
-	} else {
+	}
+	if (current == NULL || !cmd_find_valid_state(current)) {
 		error = cmd_find_current(&tmp, cmdq, targetflags);
 		if (error != 0 && ~targetflags & CMD_FIND_QUIET)
 			return (-1);
 		current = &tmp;
 	}
+	if (!cmd_find_empty_state(current) && !cmd_find_valid_state(current))
+		fatalx("invalid current state");
 
 	switch (flag) {
 	case CMD_NONE:
@@ -558,6 +561,13 @@ cmd_prepare_state(struct cmd *cmd, struct cmd_q *cmdq, struct cmd_q *parent)
 	if (error != 0)
 		return (error);
 
+	if (!cmd_find_empty_state(&state->tflag) &&
+	    !cmd_find_valid_state(&state->tflag))
+		fatalx("invalid -t state");
+	if (!cmd_find_empty_state(&state->sflag) &&
+	    !cmd_find_valid_state(&state->sflag))
+		fatalx("invalid -s state");
+
 	return (0);
 }
 

tmux.h

@@ -1730,6 +1730,7 @@ int		 cmd_find_target(struct cmd_find_state *,
 struct client	*cmd_find_client(struct cmd_q *, const char *, int);
 void		 cmd_find_clear_state(struct cmd_find_state *, struct cmd_q *,
 		     int);
+int		 cmd_find_empty_state(struct cmd_find_state *);
 int		 cmd_find_valid_state(struct cmd_find_state *);
 void		 cmd_find_copy_state(struct cmd_find_state *,
 		     struct cmd_find_state *);