Return to spawn.c CVS log

Up to [local] / src / usr.bin / tmux

Add a client flag 'active-pane' which stores the active pane in the
client and allows it to be changed independently from the real active
pane stored in the window. This is can be used with session groups which
allow an independent current window (although it would be nice to have a
flag for this too and remove session groups). The client active pane is
only really useful interactively, many things (hooks, window-style,
zooming) still use the window active pane.

/* $OpenBSD: spawn.c,v 1.23 2020/05/16 16:20:59 nicm Exp $ */

/*
 * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <errno.h>
#include <paths.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

#include "tmux.h"

/*
 * Set up the environment and create a new window and pane or a new pane.
 *
 * We need to set up the following items:
 *
 * - history limit, comes from the session;
 *
 * - base index, comes from the session;
 *
 * - current working directory, may be specified - if it isn't it comes from
 *   either the client or the session;
 *
 * - PATH variable, comes from the client if any, otherwise from the session
 *   environment;
 *
 * - shell, comes from default-shell;
 *
 * - termios, comes from the session;
 *
 * - remaining environment, comes from the session.
 */

static void
spawn_log(const char *from, struct spawn_context *sc)
{
	struct session		*s = sc->s;
	struct winlink		*wl = sc->wl;
	struct window_pane	*wp0 = sc->wp0;
	const char		*name = cmdq_get_name(sc->item);
	char			 tmp[128];

	log_debug("%s: %s, flags=%#x", from, name, sc->flags);

	if (wl != NULL && wp0 != NULL)
		xsnprintf(tmp, sizeof tmp, "wl=%d wp0=%%%u", wl->idx, wp0->id);
	else if (wl != NULL)
		xsnprintf(tmp, sizeof tmp, "wl=%d wp0=none", wl->idx);
	else if (wp0 != NULL)
		xsnprintf(tmp, sizeof tmp, "wl=none wp0=%%%u", wp0->id);
	else
		xsnprintf(tmp, sizeof tmp, "wl=none wp0=none");
	log_debug("%s: s=$%u %s idx=%d", from, s->id, tmp, sc->idx);
	log_debug("%s: name=%s", from, sc->name == NULL ? "none" : sc->name);
}

struct winlink *
spawn_window(struct spawn_context *sc, char **cause)
{
	struct cmdq_item	*item = sc->item;
	struct client		*c = cmdq_get_client(item);
	struct session		*s = sc->s;
	struct window		*w;
	struct window_pane	*wp;
	struct winlink		*wl;
	int			 idx = sc->idx;
	u_int			 sx, sy, xpixel, ypixel;

	spawn_log(__func__, sc);

	/*
	 * If the window already exists, we are respawning, so destroy all the
	 * panes except one.
	 */
	if (sc->flags & SPAWN_RESPAWN) {
		w = sc->wl->window;
		if (~sc->flags & SPAWN_KILL) {
			TAILQ_FOREACH(wp, &w->panes, entry) {
				if (wp->fd != -1)
					break;
			}
			if (wp != NULL) {
				xasprintf(cause, "window %s:%d still active",
				    s->name, sc->wl->idx);
				return (NULL);
			}
		}

		sc->wp0 = TAILQ_FIRST(&w->panes);
		TAILQ_REMOVE(&w->panes, sc->wp0, entry);

		layout_free(w);
		window_destroy_panes(w);

		TAILQ_INSERT_HEAD(&w->panes, sc->wp0, entry);
		window_pane_resize(sc->wp0, w->sx, w->sy);

		layout_init(w, sc->wp0);
		window_set_active_pane(w, sc->wp0, 0);
	}

	/*
	 * Otherwise we have no window so we will need to create one. First
	 * check if the given index already exists and destroy it if so.
	 */
	if ((~sc->flags & SPAWN_RESPAWN) && idx != -1) {
		wl = winlink_find_by_index(&s->windows, idx);
		if (wl != NULL && (~sc->flags & SPAWN_KILL)) {
			xasprintf(cause, "index %d in use", idx);
			return (NULL);
		}
		if (wl != NULL) {
			/*
			 * Can't use session_detach as it will destroy session
			 * if this makes it empty.
			 */
			wl->flags &= ~WINLINK_ALERTFLAGS;
			notify_session_window("window-unlinked", s, wl->window);
			winlink_stack_remove(&s->lastw, wl);
			winlink_remove(&s->windows, wl);

			if (s->curw == wl) {
				s->curw = NULL;
				sc->flags &= ~SPAWN_DETACHED;
			}
		}
	}

	/* Then create a window if needed. */
	if (~sc->flags & SPAWN_RESPAWN) {
		if (idx == -1)
			idx = -1 - options_get_number(s->options, "base-index");
		if ((sc->wl = winlink_add(&s->windows, idx)) == NULL) {
			xasprintf(cause, "couldn't add window %d", idx);
			return (NULL);
		}
		default_window_size(sc->tc, s, NULL, &sx, &sy, &xpixel, &ypixel,
		    -1);
		if ((w = window_create(sx, sy, xpixel, ypixel)) == NULL) {
			winlink_remove(&s->windows, sc->wl);
			xasprintf(cause, "couldn't create window %d", idx);
			return (NULL);
		}
		if (s->curw == NULL)
			s->curw = sc->wl;
		sc->wl->session = s;
		w->latest = sc->tc;
		winlink_set_window(sc->wl, w);
	} else
		w = NULL;
	sc->flags |= SPAWN_NONOTIFY;

	/* Spawn the pane. */
	wp = spawn_pane(sc, cause);
	if (wp == NULL) {
		if (~sc->flags & SPAWN_RESPAWN)
			winlink_remove(&s->windows, sc->wl);
		return (NULL);
	}

	/* Set the name of the new window. */
	if (~sc->flags & SPAWN_RESPAWN) {
		if (sc->name != NULL) {
			w->name = format_single(item, sc->name, c, s, NULL,
			    NULL);
			options_set_number(w->options, "automatic-rename", 0);
		} else
			w->name = xstrdup(default_window_name(w));
	}

	/* Switch to the new window if required. */
	if (~sc->flags & SPAWN_DETACHED)
		session_select(s, sc->wl->idx);

	/* Fire notification if new window. */
	if (~sc->flags & SPAWN_RESPAWN)
		notify_session_window("window-linked", s, w);

	session_group_synchronize_from(s);
	return (sc->wl);
}

struct window_pane *
spawn_pane(struct spawn_context *sc, char **cause)
{
	struct cmdq_item	 *item = sc->item;
	struct cmd_find_state	 *target = cmdq_get_target(item);
	struct client		 *c = cmdq_get_client(item);
	struct session		 *s = sc->s;
	struct window		 *w = sc->wl->window;
	struct window_pane	 *new_wp;
	struct environ		 *child;
	struct environ_entry	 *ee;
	char			**argv, *cp, **argvp, *argv0, *cwd;
	const char		 *cmd, *tmp;
	int			  argc;
	u_int			  idx;
	struct termios		  now;
	u_int			  hlimit;
	struct winsize		  ws;
	sigset_t		  set, oldset;
	key_code		  key;

	spawn_log(__func__, sc);

	/*
	 * Work out the current working directory. If respawning, use
	 * the pane's stored one unless specified.
	 */
	if (sc->cwd != NULL)
		cwd = format_single(item, sc->cwd, c, target->s, NULL, NULL);
	else if (~sc->flags & SPAWN_RESPAWN)
		cwd = xstrdup(server_client_get_cwd(c, target->s));
	else
		cwd = NULL;

	/*
	 * If we are respawning then get rid of the old process. Otherwise
	 * either create a new cell or assign to the one we are given.
	 */
	hlimit = options_get_number(s->options, "history-limit");
	if (sc->flags & SPAWN_RESPAWN) {
		if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) {
			window_pane_index(sc->wp0, &idx);
			xasprintf(cause, "pane %s:%d.%u still active",
			    s->name, sc->wl->idx, idx);
			free(cwd);
			return (NULL);
		}
		if (sc->wp0->fd != -1) {
			bufferevent_free(sc->wp0->event);
			close(sc->wp0->fd);
		}
		window_pane_reset_mode_all(sc->wp0);
		screen_reinit(&sc->wp0->base);
		input_free(sc->wp0->ictx);
		sc->wp0->ictx = NULL;
		new_wp = sc->wp0;
		new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN);
	} else if (sc->lc == NULL) {
		new_wp = window_add_pane(w, NULL, hlimit, sc->flags);
		layout_init(w, new_wp);
	} else {
		new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags);
		layout_assign_pane(sc->lc, new_wp);
	}

	/*
	 * Now we have a pane with nothing running in it ready for the new process.
	 * Work out the command and arguments and store the working directory.
	 */
	if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) {
		cmd = options_get_string(s->options, "default-command");
		if (cmd != NULL && *cmd != '\0') {
			argc = 1;
			argv = (char **)&cmd;
		} else {
			argc = 0;
			argv = NULL;
		}
	} else {
		argc = sc->argc;
		argv = sc->argv;
	}
	if (cwd != NULL) {
		free(new_wp->cwd);
		new_wp->cwd = cwd;
	}

	/*
	 * Replace the stored arguments if there are new ones. If not, the
	 * existing ones will be used (they will only exist for respawn).
	 */
	if (argc > 0) {
		cmd_free_argv(new_wp->argc, new_wp->argv);
		new_wp->argc = argc;
		new_wp->argv = cmd_copy_argv(argc, argv);
	}

	/* Create an environment for this pane. */
	child = environ_for_session(s, 0);
	if (sc->environ != NULL)
		environ_copy(sc->environ, child);
	environ_set(child, "TMUX_PANE", 0, "%%%u", new_wp->id);

	/*
	 * Then the PATH environment variable. The session one is replaced from
	 * the client if there is one because otherwise running "tmux new
	 * myprogram" wouldn't work if myprogram isn't in the session's path.
	 */
	if (c != NULL && c->session == NULL) { /* only unattached clients */
		ee = environ_find(c->environ, "PATH");
		if (ee != NULL)
			environ_set(child, "PATH", 0, "%s", ee->value);
	}
	if (environ_find(child, "PATH") == NULL)
		environ_set(child, "PATH", 0, "%s", _PATH_DEFPATH);

	/* Then the shell. If respawning, use the old one. */
	if (~sc->flags & SPAWN_RESPAWN) {
		tmp = options_get_string(s->options, "default-shell");
		if (!checkshell(tmp))
			tmp = _PATH_BSHELL;
		free(new_wp->shell);
		new_wp->shell = xstrdup(tmp);
	}
	environ_set(child, "SHELL", 0, "%s", new_wp->shell);

	/* Log the arguments we are going to use. */
	log_debug("%s: shell=%s", __func__, new_wp->shell);
	if (new_wp->argc != 0) {
		cp = cmd_stringify_argv(new_wp->argc, new_wp->argv);
		log_debug("%s: cmd=%s", __func__, cp);
		free(cp);
	}
	if (cwd != NULL)
		log_debug("%s: cwd=%s", __func__, cwd);
	cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__);
	environ_log(child, "%s: environment ", __func__);

	/* Initialize the window size. */
	memset(&ws, 0, sizeof ws);
	ws.ws_col = screen_size_x(&new_wp->base);
	ws.ws_row = screen_size_y(&new_wp->base);
	ws.ws_xpixel = w->xpixel * ws.ws_col;
	ws.ws_ypixel = w->ypixel * ws.ws_row;

	/* Block signals until fork has completed. */
	sigfillset(&set);
	sigprocmask(SIG_BLOCK, &set, &oldset);

	/* If the command is empty, don't fork a child process. */
	if (sc->flags & SPAWN_EMPTY) {
		new_wp->flags |= PANE_EMPTY;
		new_wp->base.mode &= ~MODE_CURSOR;
		new_wp->base.mode |= MODE_CRLF;
		goto complete;
	}

	/* Fork the new process. */
	new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws);
	if (new_wp->pid == -1) {
		xasprintf(cause, "fork failed: %s", strerror(errno));
		new_wp->fd = -1;
		if (~sc->flags & SPAWN_RESPAWN) {
			server_client_remove_pane(new_wp);
			layout_close_pane(new_wp);
			window_remove_pane(w, new_wp);
		}
		sigprocmask(SIG_SETMASK, &oldset, NULL);
		environ_free(child);
		return (NULL);
	}

	/* In the parent process, everything is done now. */
	if (new_wp->pid != 0)
		goto complete;

	/*
	 * Child process. Change to the working directory or home if that
	 * fails.
	 */
	if (chdir(new_wp->cwd) != 0) {
		if ((tmp = find_home()) == NULL || chdir(tmp) != 0)
			chdir("/");
	}

	/*
	 * Update terminal escape characters from the session if available and
	 * force VERASE to tmux's backspace.
	 */
	if (tcgetattr(STDIN_FILENO, &now) != 0)
		_exit(1);
	if (s->tio != NULL)
		memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc);
	key = options_get_number(global_options, "backspace");
	if (key >= 0x7f)
		now.c_cc[VERASE] = '\177';
	else
		now.c_cc[VERASE] = key;
	if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0)
		_exit(1);

	/* Clean up file descriptors and signals and update the environment. */
	closefrom(STDERR_FILENO + 1);
	proc_clear_signals(server_proc, 1);
	sigprocmask(SIG_SETMASK, &oldset, NULL);
	log_close();
	environ_push(child);

	/*
	 * If given multiple arguments, use execvp(). Copy the arguments to
	 * ensure they end in a NULL.
	 */
	if (new_wp->argc != 0 && new_wp->argc != 1) {
		argvp = cmd_copy_argv(new_wp->argc, new_wp->argv);
		execvp(argvp[0], argvp);
		_exit(1);
	}

	/*
	 * If one argument, pass it to $SHELL -c. Otherwise create a login
	 * shell.
	 */
	cp = strrchr(new_wp->shell, '/');
	if (new_wp->argc == 1) {
		tmp = new_wp->argv[0];
		if (cp != NULL && cp[1] != '\0')
			xasprintf(&argv0, "%s", cp + 1);
		else
			xasprintf(&argv0, "%s", new_wp->shell);
		execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL);
		_exit(1);
	}
	if (cp != NULL && cp[1] != '\0')
		xasprintf(&argv0, "-%s", cp + 1);
	else
		xasprintf(&argv0, "-%s", new_wp->shell);
	execl(new_wp->shell, argv0, (char *)NULL);
	_exit(1);

complete:
	new_wp->pipe_off = 0;
	new_wp->flags &= ~PANE_EXITED;

	sigprocmask(SIG_SETMASK, &oldset, NULL);
	window_pane_set_event(new_wp);

	environ_free(child);

	if (sc->flags & SPAWN_RESPAWN)
		return (new_wp);
	if ((~sc->flags & SPAWN_DETACHED) || w->active == NULL) {
		if (sc->flags & SPAWN_NONOTIFY)
			window_set_active_pane(w, new_wp, 0);
		else
			window_set_active_pane(w, new_wp, 1);
	}
	if (~sc->flags & SPAWN_NONOTIFY)
		notify_window("window-layout-changed", w);
	return (new_wp);
}