spawn.c

   1 /* $OpenBSD$ */
   2
   3 /*
   4  * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
  15  * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
  16  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include <sys/types.h>
  20
  21 #include <errno.h>
  22 #include <paths.h>
  23 #include <signal.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <util.h>
  28
  29 #include "tmux.h"
  30
  31 /*
  32  * Set up the environment and create a new window and pane or a new pane.
  33  *
  34  * We need to set up the following items:
  35  *
  36  * - history limit, comes from the session;
  37  *
  38  * - base index, comes from the session;
  39  *
  40  * - current working directory, may be specified - if it isn't it comes from
  41  *   either the client or the session;
  42  *
  43  * - PATH variable, comes from the client if any, otherwise from the session
  44  *   environment;
  45  *
  46  * - shell, comes from default-shell;
  47  *
  48  * - termios, comes from the session;
  49  *
  50  * - remaining environment, comes from the session.
  51  */
  52
  53 static void
  54 spawn_log(const char *from, struct spawn_context *sc)
  55 {
  56         struct session          *s = sc->s;
  57         struct winlink          *wl = sc->wl;
  58         struct window_pane      *wp0 = sc->wp0;
  59         const char              *name = cmdq_get_name(sc->item);
  60         char                     tmp[128];
  61
  62         log_debug("%s: %s, flags=%#x", from, name, sc->flags);
  63
  64         if (wl != NULL && wp0 != NULL)
  65                 xsnprintf(tmp, sizeof tmp, "wl=%d wp0=%%%u", wl->idx, wp0->id);
  66         else if (wl != NULL)
  67                 xsnprintf(tmp, sizeof tmp, "wl=%d wp0=none", wl->idx);
  68         else if (wp0 != NULL)
  69                 xsnprintf(tmp, sizeof tmp, "wl=none wp0=%%%u", wp0->id);
  70         else
  71                 xsnprintf(tmp, sizeof tmp, "wl=none wp0=none");
  72         log_debug("%s: s=$%u %s idx=%d", from, s->id, tmp, sc->idx);
  73         log_debug("%s: name=%s", from, sc->name == NULL ? "none" : sc->name);
  74 }
  75
  76 struct winlink *
  77 spawn_window(struct spawn_context *sc, char **cause)
  78 {
  79         struct cmdq_item        *item = sc->item;
  80         struct client           *c = cmdq_get_client(item);
  81         struct session          *s = sc->s;
  82         struct window           *w;
  83         struct window_pane      *wp;
  84         struct winlink          *wl;
  85         int                      idx = sc->idx;
  86         u_int                    sx, sy, xpixel, ypixel;
  87
  88         spawn_log(__func__, sc);
  89
  90         /*
  91          * If the window already exists, we are respawning, so destroy all the
  92          * panes except one.
  93          */
  94         if (sc->flags & SPAWN_RESPAWN) {
  95                 w = sc->wl->window;
  96                 if (~sc->flags & SPAWN_KILL) {
  97                         TAILQ_FOREACH(wp, &w->panes, entry) {
  98                                 if (wp->fd != -1)
  99                                         break;
 100                         }
 101                         if (wp != NULL) {
 102                                 xasprintf(cause, "window %s:%d still active",
 103                                     s->name, sc->wl->idx);
 104                                 return (NULL);
 105                         }
 106                 }
 107
 108                 sc->wp0 = TAILQ_FIRST(&w->panes);
 109                 TAILQ_REMOVE(&w->panes, sc->wp0, entry);
 110
 111                 layout_free(w);
 112                 window_destroy_panes(w);
 113
 114                 TAILQ_INSERT_HEAD(&w->panes, sc->wp0, entry);
 115                 window_pane_resize(sc->wp0, w->sx, w->sy);
 116
 117                 layout_init(w, sc->wp0);
 118                 w->active = NULL;
 119                 window_set_active_pane(w, sc->wp0, 0);
 120         }
 121
 122         /*
 123          * Otherwise we have no window so we will need to create one. First
 124          * check if the given index already exists and destroy it if so.
 125          */
 126         if ((~sc->flags & SPAWN_RESPAWN) && idx != -1) {
 127                 wl = winlink_find_by_index(&s->windows, idx);
 128                 if (wl != NULL && (~sc->flags & SPAWN_KILL)) {
 129                         xasprintf(cause, "index %d in use", idx);
 130                         return (NULL);
 131                 }
 132                 if (wl != NULL) {
 133                         /*
 134                          * Can't use session_detach as it will destroy session
 135                          * if this makes it empty.
 136                          */
 137                         wl->flags &= ~WINLINK_ALERTFLAGS;
 138                         notify_session_window("window-unlinked", s, wl->window);
 139                         winlink_stack_remove(&s->lastw, wl);
 140                         winlink_remove(&s->windows, wl);
 141
 142                         if (s->curw == wl) {
 143                                 s->curw = NULL;
 144                                 sc->flags &= ~SPAWN_DETACHED;
 145                         }
 146                 }
 147         }
 148
 149         /* Then create a window if needed. */
 150         if (~sc->flags & SPAWN_RESPAWN) {
 151                 if (idx == -1)
 152                         idx = -1 - options_get_number(s->options, "base-index");
 153                 if ((sc->wl = winlink_add(&s->windows, idx)) == NULL) {
 154                         xasprintf(cause, "couldn't add window %d", idx);
 155                         return (NULL);
 156                 }
 157                 default_window_size(sc->tc, s, NULL, &sx, &sy, &xpixel, &ypixel,
 158                     -1);
 159                 if ((w = window_create(sx, sy, xpixel, ypixel)) == NULL) {
 160                         winlink_remove(&s->windows, sc->wl);
 161                         xasprintf(cause, "couldn't create window %d", idx);
 162                         return (NULL);
 163                 }
 164                 if (s->curw == NULL)
 165                         s->curw = sc->wl;
 166                 sc->wl->session = s;
 167                 w->latest = sc->tc;
 168                 winlink_set_window(sc->wl, w);
 169         } else
 170                 w = NULL;
 171         sc->flags |= SPAWN_NONOTIFY;
 172
 173         /* Spawn the pane. */
 174         wp = spawn_pane(sc, cause);
 175         if (wp == NULL) {
 176                 if (~sc->flags & SPAWN_RESPAWN)
 177                         winlink_remove(&s->windows, sc->wl);
 178                 return (NULL);
 179         }
 180
 181         /* Set the name of the new window. */
 182         if (~sc->flags & SPAWN_RESPAWN) {
 183                 free(w->name);
 184                 if (sc->name != NULL) {
 185                         w->name = format_single(item, sc->name, c, s, NULL,
 186                             NULL);
 187                         options_set_number(w->options, "automatic-rename", 0);
 188                 } else
 189                         w->name = default_window_name(w);
 190         }
 191
 192         /* Switch to the new window if required. */
 193         if (~sc->flags & SPAWN_DETACHED)
 194                 session_select(s, sc->wl->idx);
 195
 196         /* Fire notification if new window. */
 197         if (~sc->flags & SPAWN_RESPAWN)
 198                 notify_session_window("window-linked", s, w);
 199
 200         session_group_synchronize_from(s);
 201         return (sc->wl);
 202 }
 203
 204 struct window_pane *
 205 spawn_pane(struct spawn_context *sc, char **cause)
 206 {
 207         struct cmdq_item         *item = sc->item;
 208         struct cmd_find_state    *target = cmdq_get_target(item);
 209         struct client            *c = cmdq_get_client(item);
 210         struct session           *s = sc->s;
 211         struct window            *w = sc->wl->window;
 212         struct window_pane       *new_wp;
 213         struct environ           *child;
 214         struct environ_entry     *ee;
 215         char                    **argv, *cp, **argvp, *argv0, *cwd, *new_cwd;
 216         const char               *cmd, *tmp;
 217         int                       argc;
 218         u_int                     idx;
 219         struct termios            now;
 220         u_int                     hlimit;
 221         struct winsize            ws;
 222         sigset_t                  set, oldset;
 223         key_code                  key;
 224
 225         spawn_log(__func__, sc);
 226
 227         /*
 228          * Work out the current working directory. If respawning, use
 229          * the pane's stored one unless specified.
 230          */
 231         if (sc->cwd != NULL) {
 232                 cwd = format_single(item, sc->cwd, c, target->s, NULL, NULL);
 233                 if (*cwd != '/') {
 234                         xasprintf(&new_cwd, "%s/%s", server_client_get_cwd(c,
 235                             target->s), cwd);
 236                         free(cwd);
 237                         cwd = new_cwd;
 238                 }
 239         } else if (~sc->flags & SPAWN_RESPAWN)
 240                 cwd = xstrdup(server_client_get_cwd(c, target->s));
 241         else
 242                 cwd = NULL;
 243
 244         /*
 245          * If we are respawning then get rid of the old process. Otherwise
 246          * either create a new cell or assign to the one we are given.
 247          */
 248         hlimit = options_get_number(s->options, "history-limit");
 249         if (sc->flags & SPAWN_RESPAWN) {
 250                 if (sc->wp0->fd != -1 && (~sc->flags & SPAWN_KILL)) {
 251                         window_pane_index(sc->wp0, &idx);
 252                         xasprintf(cause, "pane %s:%d.%u still active",
 253                             s->name, sc->wl->idx, idx);
 254                         free(cwd);
 255                         return (NULL);
 256                 }
 257                 if (sc->wp0->fd != -1) {
 258                         bufferevent_free(sc->wp0->event);
 259                         close(sc->wp0->fd);
 260                 }
 261                 window_pane_reset_mode_all(sc->wp0);
 262                 screen_reinit(&sc->wp0->base);
 263                 input_free(sc->wp0->ictx);
 264                 sc->wp0->ictx = NULL;
 265                 new_wp = sc->wp0;
 266                 new_wp->flags &= ~(PANE_STATUSREADY|PANE_STATUSDRAWN);
 267         } else if (sc->lc == NULL) {
 268                 new_wp = window_add_pane(w, NULL, hlimit, sc->flags);
 269                 layout_init(w, new_wp);
 270         } else {
 271                 new_wp = window_add_pane(w, sc->wp0, hlimit, sc->flags);
 272                 if (sc->flags & SPAWN_ZOOM)
 273                         layout_assign_pane(sc->lc, new_wp, 1);
 274                 else
 275                         layout_assign_pane(sc->lc, new_wp, 0);
 276         }
 277
 278         /*
 279          * Now we have a pane with nothing running in it ready for the new
 280          * process. Work out the command and arguments and store the working
 281          * directory.
 282          */
 283         if (sc->argc == 0 && (~sc->flags & SPAWN_RESPAWN)) {
 284                 cmd = options_get_string(s->options, "default-command");
 285                 if (cmd != NULL && *cmd != '\0') {
 286                         argc = 1;
 287                         argv = (char **)&cmd;
 288                 } else {
 289                         argc = 0;
 290                         argv = NULL;
 291                 }
 292         } else {
 293                 argc = sc->argc;
 294                 argv = sc->argv;
 295         }
 296         if (cwd != NULL) {
 297                 free(new_wp->cwd);
 298                 new_wp->cwd = cwd;
 299         }
 300
 301         /*
 302          * Replace the stored arguments if there are new ones. If not, the
 303          * existing ones will be used (they will only exist for respawn).
 304          */
 305         if (argc > 0) {
 306                 cmd_free_argv(new_wp->argc, new_wp->argv);
 307                 new_wp->argc = argc;
 308                 new_wp->argv = cmd_copy_argv(argc, argv);
 309         }
 310
 311         /* Create an environment for this pane. */
 312         child = environ_for_session(s, 0);
 313         if (sc->environ != NULL)
 314                 environ_copy(sc->environ, child);
 315         environ_set(child, "TMUX_PANE", 0, "%%%u", new_wp->id);
 316
 317         /*
 318          * Then the PATH environment variable. The session one is replaced from
 319          * the client if there is one because otherwise running "tmux new
 320          * myprogram" wouldn't work if myprogram isn't in the session's path.
 321          */
 322         if (c != NULL && c->session == NULL) { /* only unattached clients */
 323                 ee = environ_find(c->environ, "PATH");
 324                 if (ee != NULL)
 325                         environ_set(child, "PATH", 0, "%s", ee->value);
 326         }
 327         if (environ_find(child, "PATH") == NULL)
 328                 environ_set(child, "PATH", 0, "%s", _PATH_DEFPATH);
 329
 330         /* Then the shell. If respawning, use the old one. */
 331         if (~sc->flags & SPAWN_RESPAWN) {
 332                 tmp = options_get_string(s->options, "default-shell");
 333                 if (!checkshell(tmp))
 334                         tmp = _PATH_BSHELL;
 335                 free(new_wp->shell);
 336                 new_wp->shell = xstrdup(tmp);
 337         }
 338         environ_set(child, "SHELL", 0, "%s", new_wp->shell);
 339
 340         /* Log the arguments we are going to use. */
 341         log_debug("%s: shell=%s", __func__, new_wp->shell);
 342         if (new_wp->argc != 0) {
 343                 cp = cmd_stringify_argv(new_wp->argc, new_wp->argv);
 344                 log_debug("%s: cmd=%s", __func__, cp);
 345                 free(cp);
 346         }
 347         log_debug("%s: cwd=%s", __func__, new_wp->cwd);
 348         cmd_log_argv(new_wp->argc, new_wp->argv, "%s", __func__);
 349         environ_log(child, "%s: environment ", __func__);
 350
 351         /* Initialize the window size. */
 352         memset(&ws, 0, sizeof ws);
 353         ws.ws_col = screen_size_x(&new_wp->base);
 354         ws.ws_row = screen_size_y(&new_wp->base);
 355         ws.ws_xpixel = w->xpixel * ws.ws_col;
 356         ws.ws_ypixel = w->ypixel * ws.ws_row;
 357
 358         /* Block signals until fork has completed. */
 359         sigfillset(&set);
 360         sigprocmask(SIG_BLOCK, &set, &oldset);
 361
 362         /* If the command is empty, don't fork a child process. */
 363         if (sc->flags & SPAWN_EMPTY) {
 364                 new_wp->flags |= PANE_EMPTY;
 365                 new_wp->base.mode &= ~MODE_CURSOR;
 366                 new_wp->base.mode |= MODE_CRLF;
 367                 goto complete;
 368         }
 369
 370         /* Fork the new process. */
 371         new_wp->pid = fdforkpty(ptm_fd, &new_wp->fd, new_wp->tty, NULL, &ws);
 372         if (new_wp->pid == -1) {
 373                 xasprintf(cause, "fork failed: %s", strerror(errno));
 374                 new_wp->fd = -1;
 375                 if (~sc->flags & SPAWN_RESPAWN) {
 376                         server_client_remove_pane(new_wp);
 377                         layout_close_pane(new_wp);
 378                         window_remove_pane(w, new_wp);
 379                 }
 380                 sigprocmask(SIG_SETMASK, &oldset, NULL);
 381                 environ_free(child);
 382                 return (NULL);
 383         }
 384
 385         /* In the parent process, everything is done now. */
 386         if (new_wp->pid != 0)
 387                 goto complete;
 388
 389         /*
 390          * Child process. Change to the working directory or home if that
 391          * fails.
 392          */
 393         if (chdir(new_wp->cwd) == 0)
 394                 environ_set(child, "PWD", 0, "%s", new_wp->cwd);
 395         else if ((tmp = find_home()) != NULL && chdir(tmp) == 0)
 396                 environ_set(child, "PWD", 0, "%s", tmp);
 397         else if (chdir("/") == 0)
 398                 environ_set(child, "PWD", 0, "/");
 399         else
 400                 fatal("chdir failed");
 401
 402         /*
 403          * Update terminal escape characters from the session if available and
 404          * force VERASE to tmux's backspace.
 405          */
 406         if (tcgetattr(STDIN_FILENO, &now) != 0)
 407                 _exit(1);
 408         if (s->tio != NULL)
 409                 memcpy(now.c_cc, s->tio->c_cc, sizeof now.c_cc);
 410         key = options_get_number(global_options, "backspace");
 411         if (key >= 0x7f)
 412                 now.c_cc[VERASE] = '\177';
 413         else
 414                 now.c_cc[VERASE] = key;
 415         if (tcsetattr(STDIN_FILENO, TCSANOW, &now) != 0)
 416                 _exit(1);
 417
 418         /* Clean up file descriptors and signals and update the environment. */
 419         proc_clear_signals(server_proc, 1);
 420         closefrom(STDERR_FILENO + 1);
 421         sigprocmask(SIG_SETMASK, &oldset, NULL);
 422         log_close();
 423         environ_push(child);
 424
 425         /*
 426          * If given multiple arguments, use execvp(). Copy the arguments to
 427          * ensure they end in a NULL.
 428          */
 429         if (new_wp->argc != 0 && new_wp->argc != 1) {
 430                 argvp = cmd_copy_argv(new_wp->argc, new_wp->argv);
 431                 execvp(argvp[0], argvp);
 432                 _exit(1);
 433         }
 434
 435         /*
 436          * If one argument, pass it to $SHELL -c. Otherwise create a login
 437          * shell.
 438          */
 439         cp = strrchr(new_wp->shell, '/');
 440         if (new_wp->argc == 1) {
 441                 tmp = new_wp->argv[0];
 442                 if (cp != NULL && cp[1] != '\0')
 443                         xasprintf(&argv0, "%s", cp + 1);
 444                 else
 445                         xasprintf(&argv0, "%s", new_wp->shell);
 446                 execl(new_wp->shell, argv0, "-c", tmp, (char *)NULL);
 447                 _exit(1);
 448         }
 449         if (cp != NULL && cp[1] != '\0')
 450                 xasprintf(&argv0, "-%s", cp + 1);
 451         else
 452                 xasprintf(&argv0, "-%s", new_wp->shell);
 453         execl(new_wp->shell, argv0, (char *)NULL);
 454         _exit(1);
 455
 456 complete:
 457         new_wp->flags &= ~PANE_EXITED;
 458
 459         sigprocmask(SIG_SETMASK, &oldset, NULL);
 460         window_pane_set_event(new_wp);
 461
 462         environ_free(child);
 463
 464         if (sc->flags & SPAWN_RESPAWN)
 465                 return (new_wp);
 466         if ((~sc->flags & SPAWN_DETACHED) || w->active == NULL) {
 467                 if (sc->flags & SPAWN_NONOTIFY)
 468                         window_set_active_pane(w, new_wp, 0);
 469                 else
 470                         window_set_active_pane(w, new_wp, 1);
 471         }
 472         if (~sc->flags & SPAWN_NONOTIFY)
 473                 notify_window("window-layout-changed", w);
 474         return (new_wp);
 475 }