tmux/spawn.c
Nicholas Marriott b9524f5b72 Add support for spawning panes in separate cgroups with systemd and a configure
flag to disable. From Eric T Johnson yut23 AT gvljohnsons DOT com in GitHub
issue 3514.
2023-04-03 08:54:06 +01:00

497 lines
14 KiB
C

/* $OpenBSD$ */
/*
* 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 <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.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) {
free(w->name);
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 = 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, *new_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);
if (*cwd != '/') {
xasprintf(&new_cwd, "%s/%s", server_client_get_cwd(c,
target->s), cwd);
free(cwd);
cwd = new_cwd;
}
} 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);
if (sc->flags & SPAWN_ZOOM)
layout_assign_pane(sc->lc, new_wp, 1);
else
layout_assign_pane(sc->lc, new_wp, 0);
}
/*
* 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);
}
log_debug("%s: cwd=%s", __func__, new_wp->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) {
#if defined(HAVE_SYSTEMD) && defined(ENABLE_CGROUPS)
/*
* Move the child process into a new cgroup for systemd-oomd
* isolation.
*/
if (systemd_move_pid_to_new_cgroup(new_wp->pid, cause) < 0) {
log_debug("%s: moving pane to new cgroup failed: %s",
__func__, *cause);
free (*cause);
}
#endif
goto complete;
}
/*
* Child process. Change to the working directory or home if that
* fails.
*/
if (chdir(new_wp->cwd) == 0)
environ_set(child, "PWD", 0, "%s", new_wp->cwd);
else if ((tmp = find_home()) != NULL && chdir(tmp) == 0)
environ_set(child, "PWD", 0, "%s", tmp);
else if (chdir("/") == 0)
environ_set(child, "PWD", 0, "/");
else
fatal("chdir failed");
/*
* 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;
#ifdef IUTF8
now.c_iflag |= IUTF8;
#endif
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:
#ifdef HAVE_UTEMPTER
if (~new_wp->flags & PANE_EMPTY) {
xasprintf(&cp, "tmux(%lu).%%%u", (long)getpid(), new_wp->id);
utempter_add_record(new_wp->fd, cp);
kill(getpid(), SIGCHLD);
free(cp);
}
#endif
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);
}