vtespawn.cc 33.9 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
/* gspawn.c - Process launching
 *
 *  Copyright 2000 Red Hat, Inc.
 *  g_execvpe implementation based on GNU libc execvp:
 *   Copyright 1991, 92, 95, 96, 97, 98, 99 Free Software Foundation, Inc.
 *
 * GLib is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * GLib is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with GLib; see the file COPYING.LIB.  If not, write
 * to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>   /* for fdwalk */
#include <dirent.h>

#ifdef HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif /* HAVE_SYS_RESOURCE_H */

#include <glib-unix.h>

41 42 43 44
#ifdef __linux__
#include <sys/syscall.h>  /* for syscall and SYS_getdents64 */
#endif

45
#include "vtespawn.hh"
46
#include "vteutils.h"  /* for strchrnul on non-GNU systems */
47 48 49 50 51
#include "reaper.hh"

#define VTE_SPAWN_ERROR_TIMED_OUT (G_SPAWN_ERROR_FAILED + 1000)
#define VTE_SPAWN_ERROR_CANCELLED (G_SPAWN_ERROR_FAILED + 1001)

52
#define _(s) g_dgettext("glib20", s)
53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160

/*
 * SECTION:spawn
 * @Short_description: process launching
 * @Title: Spawning Processes
 *
 * GLib supports spawning of processes with an API that is more
 * convenient than the bare UNIX fork() and exec().
 *
 * The vte_spawn family of functions has synchronous (vte_spawn_sync())
 * and asynchronous variants (vte_spawn_async(), vte_spawn_async_with_pipes(),
 * vte_spawn_async_cancellable(), vte_spawn_async_with_pipes_cancellable),
 * as well as convenience variants that take a complete shell-like
 * commandline (vte_spawn_command_line_sync(), vte_spawn_command_line_async()).
 *
 * See #GSubprocess in GIO for a higher-level API that provides
 * stream interfaces for communication with child processes.
 */

static gint g_execute (const gchar  *file,
                       gchar **argv,
                       gchar **envp,
                       gboolean search_path,
                       gboolean search_path_from_envp);

static gboolean fork_exec_with_pipes (gboolean              intermediate_child,
                                      const gchar          *working_directory,
                                      gchar               **argv,
                                      gchar               **envp,
                                      gboolean              close_descriptors,
                                      gboolean              search_path,
                                      gboolean              search_path_from_envp,
                                      gboolean              stdout_to_null,
                                      gboolean              stderr_to_null,
                                      gboolean              child_inherits_stdin,
                                      gboolean              file_and_argv_zero,
                                      gboolean              cloexec_pipes,
                                      GSpawnChildSetupFunc  child_setup,
                                      gpointer              user_data,
                                      GPid                 *child_pid,
                                      gint                 *standard_input,
                                      gint                 *standard_output,
                                      gint                 *standard_error,
                                      gint                  timeout,
                                      GPollFD              *pollfd,
                                      GError              **error);

/*
 * vte_spawn_async_cancellable:
 * @working_directory: (type filename) (allow-none): child's current working directory, or %NULL to inherit parent's
 * @argv: (array zero-terminated=1): child's argument vector
 * @envp: (array zero-terminated=1) (allow-none): child's environment, or %NULL to inherit parent's
 * @flags: flags from #GSpawnFlags
 * @child_setup: (scope async) (allow-none): function to run in the child just before exec()
 * @user_data: (closure): user data for @child_setup
 * @child_pid: (out) (allow-none): return location for child process reference, or %NULL
 * @timeout: a timeout value in ms, or -1 to wait indefinitely
 * @pollfd: (allow-none): a #GPollFD, or %NULL
 * @error: return location for error
 * 
 * See vte_spawn_async_with_pipes_cancellable() for a full description; this function
 * simply calls the vte_spawn_async_with_pipes_cancellable() without any pipes.
 *
 * You should call vte_spawn_close_pid() on the returned child process
 * reference when you don't need it any more.
 * 
 * Note that the returned @child_pid on Windows is a handle to the child
 * process and not its identifier. Process handles and process identifiers
 * are different concepts on Windows.
 *
 * Returns: %TRUE on success, %FALSE if error is set
 *
 * Since: 2.52
 **/
gboolean
vte_spawn_async_cancellable (const gchar          *working_directory,
                             gchar               **argv,
                             gchar               **envp,
                             GSpawnFlags           flags,
                             GSpawnChildSetupFunc  child_setup,
                             gpointer              user_data,
                             GPid                 *child_pid,
                             gint                  timeout,
                             GPollFD              *pollfd,
                             GError              **error)
{
  return vte_spawn_async_with_pipes_cancellable (working_directory,
                                               argv, envp,
                                               flags,
                                               child_setup,
                                               user_data,
                                               child_pid,
                                               NULL, NULL, NULL,
                                               timeout, pollfd,
                                               error);
}

/* Avoids a danger in threaded situations (calling close()
 * on a file descriptor twice, and another thread has
 * re-opened it since the first close)
 */
static void
close_and_invalidate (gint *fd)
{
  if (*fd < 0)
    return;
  else
    {
Christian Persch's avatar
Christian Persch committed
161
      (void)close(*fd);
162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416
      *fd = -1;
    }
}

/*
 * vte_spawn_async_with_pipes_cancellable:
 * @working_directory: (type filename) (allow-none): child's current working directory, or %NULL to inherit parent's, in the GLib file name encoding
 * @argv: (array zero-terminated=1): child's argument vector, in the GLib file name encoding
 * @envp: (array zero-terminated=1) (allow-none): child's environment, or %NULL to inherit parent's, in the GLib file name encoding
 * @flags: flags from #GSpawnFlags
 * @child_setup: (scope async) (allow-none): function to run in the child just before exec()
 * @user_data: (closure): user data for @child_setup
 * @child_pid: (out) (allow-none): return location for child process ID, or %NULL
 * @standard_input: (out) (allow-none): return location for file descriptor to write to child's stdin, or %NULL
 * @standard_output: (out) (allow-none): return location for file descriptor to read child's stdout, or %NULL
 * @standard_error: (out) (allow-none): return location for file descriptor to read child's stderr, or %NULL
 * @timeout: a timeout value in ms, or -1 to wait indefinitely
 * @pollfd: (allow-none): a #GPollFD, or %NULL
 * @error: return location for error
 *
 * Like vte_spawn_async_with_pipes(), but allows the spawning to be
 * aborted.
 *
 * If @timeout is not -1, then the spawning will be aborted if
 * the timeout is exceeded before spawning has completed.
 *
 * If @pollfd is not %NULL, then the spawning will be aborted if
 * the @pollfd.fd becomes readable. Usually, you want to create
 * this parameter with g_cancellable_make_pollfd().
 *
 * Returns: %TRUE on success, %FALSE if an error occurred or the
 *  spawning was aborted
 *
 * Since: 2.52
 */
gboolean
vte_spawn_async_with_pipes_cancellable (const gchar          *working_directory,
                                        gchar               **argv,
                                        gchar               **envp,
                                        GSpawnFlags           flags,
                                        GSpawnChildSetupFunc  child_setup,
                                        gpointer              user_data,
                                        GPid                 *child_pid,
                                        gint                 *standard_input,
                                        gint                 *standard_output,
                                        gint                 *standard_error,
                                        gint                  timeout,
                                        GPollFD              *pollfd,
                                        GError              **error)
{
  g_return_val_if_fail (argv != NULL, FALSE);
  g_return_val_if_fail (standard_output == NULL ||
                        !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
  g_return_val_if_fail (standard_error == NULL ||
                        !(flags & G_SPAWN_STDERR_TO_DEV_NULL), FALSE);
  /* can't inherit stdin if we have an input pipe. */
  g_return_val_if_fail (standard_input == NULL ||
                        !(flags & G_SPAWN_CHILD_INHERITS_STDIN), FALSE);
  
  return fork_exec_with_pipes (!(flags & G_SPAWN_DO_NOT_REAP_CHILD),
                               working_directory,
                               argv,
                               envp,
                               !(flags & G_SPAWN_LEAVE_DESCRIPTORS_OPEN),
                               (flags & G_SPAWN_SEARCH_PATH) != 0,
                               (flags & G_SPAWN_SEARCH_PATH_FROM_ENVP) != 0,
                               (flags & G_SPAWN_STDOUT_TO_DEV_NULL) != 0,
                               (flags & G_SPAWN_STDERR_TO_DEV_NULL) != 0,
                               (flags & G_SPAWN_CHILD_INHERITS_STDIN) != 0,
                               (flags & G_SPAWN_FILE_AND_ARGV_ZERO) != 0,
                               (flags & G_SPAWN_CLOEXEC_PIPES) != 0,
                               child_setup,
                               user_data,
                               child_pid,
                               standard_input,
                               standard_output,
                               standard_error,
                               timeout,
                               pollfd,
                               error);
}

static gint
exec_err_to_g_error (gint en)
{
  switch (en)
    {
#ifdef EACCES
    case EACCES:
      return G_SPAWN_ERROR_ACCES;
      break;
#endif

#ifdef EPERM
    case EPERM:
      return G_SPAWN_ERROR_PERM;
      break;
#endif

#ifdef E2BIG
    case E2BIG:
      return G_SPAWN_ERROR_TOO_BIG;
      break;
#endif

#ifdef ENOEXEC
    case ENOEXEC:
      return G_SPAWN_ERROR_NOEXEC;
      break;
#endif

#ifdef ENAMETOOLONG
    case ENAMETOOLONG:
      return G_SPAWN_ERROR_NAMETOOLONG;
      break;
#endif

#ifdef ENOENT
    case ENOENT:
      return G_SPAWN_ERROR_NOENT;
      break;
#endif

#ifdef ENOMEM
    case ENOMEM:
      return G_SPAWN_ERROR_NOMEM;
      break;
#endif

#ifdef ENOTDIR
    case ENOTDIR:
      return G_SPAWN_ERROR_NOTDIR;
      break;
#endif

#ifdef ELOOP
    case ELOOP:
      return G_SPAWN_ERROR_LOOP;
      break;
#endif
      
#ifdef ETXTBUSY
    case ETXTBUSY:
      return G_SPAWN_ERROR_TXTBUSY;
      break;
#endif

#ifdef EIO
    case EIO:
      return G_SPAWN_ERROR_IO;
      break;
#endif

#ifdef ENFILE
    case ENFILE:
      return G_SPAWN_ERROR_NFILE;
      break;
#endif

#ifdef EMFILE
    case EMFILE:
      return G_SPAWN_ERROR_MFILE;
      break;
#endif

#ifdef EINVAL
    case EINVAL:
      return G_SPAWN_ERROR_INVAL;
      break;
#endif

#ifdef EISDIR
    case EISDIR:
      return G_SPAWN_ERROR_ISDIR;
      break;
#endif

#ifdef ELIBBAD
    case ELIBBAD:
      return G_SPAWN_ERROR_LIBBAD;
      break;
#endif
      
    default:
      return G_SPAWN_ERROR_FAILED;
      break;
    }
}

static gssize
write_all (gint fd, gconstpointer vbuf, gsize to_write)
{
  gchar *buf = (gchar *) vbuf;
  
  while (to_write > 0)
    {
      gssize count = write (fd, buf, to_write);
      if (count < 0)
        {
          if (errno != EINTR)
            return FALSE;
        }
      else
        {
          to_write -= count;
          buf += count;
        }
    }
  
  return TRUE;
}

G_GNUC_NORETURN
static void
write_err_and_exit (gint fd, gint msg)
{
  gint en = errno;
  
  write_all (fd, &msg, sizeof(msg));
  write_all (fd, &en, sizeof(en));
  
  _exit (1);
}

static int
fd_set_cloexec(int fd)
{
        int flags = fcntl(fd, F_GETFD, 0);
        if (flags < 0)
                return flags;

        return fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}

static int
fd_set_nonblocking(int fd)
{
        int flags = fcntl(fd, F_GETFL, 0);
        if (flags < 0)
                return -1;
        if ((flags & O_NONBLOCK) != 0)
                return 0;
        return fcntl(fd, F_SETFL, flags | O_NONBLOCK);
}

static int
set_cloexec (void *data, gint fd)
{
  if (fd >= GPOINTER_TO_INT (data))
    fd_set_cloexec (fd);

  return 0;
}

#ifndef HAVE_FDWALK
417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454
#ifdef __linux__
struct linux_dirent64
{
  guint64        d_ino;    /* 64-bit inode number */
  guint64        d_off;    /* 64-bit offset to next structure */
  unsigned short d_reclen; /* Size of this dirent */
  unsigned char  d_type;   /* File type */
  char           d_name[]; /* Filename (null-terminated) */
};

static gint
filename_to_fd (const char *p)
{
  char c;
  int fd = 0;
  const int cutoff = G_MAXINT / 10;
  const int cutlim = G_MAXINT % 10;

  if (*p == '\0')
    return -1;

  while ((c = *p++) != '\0')
    {
      if (!g_ascii_isdigit (c))
        return -1;
      c -= '0';

      /* Check for overflow. */
      if (fd > cutoff || (fd == cutoff && c > cutlim))
        return -1;

      fd = fd * 10 + c;
    }

  return fd;
}
#endif

455 456 457 458 459 460 461 462 463 464 465
static int
fdwalk (int (*cb)(void *data, int fd), void *data)
{
  gint open_max;
  gint fd;
  gint res = 0;
  
#ifdef HAVE_SYS_RESOURCE_H
  struct rlimit rl;
#endif

466 467 468 469 470 471 472 473
#ifdef __linux__
  /* Avoid use of opendir/closedir since these are not async-signal-safe. */
  int dir_fd = open ("/proc/self/fd", O_RDONLY | O_DIRECTORY);
  if (dir_fd >= 0)
    {
      char buf[4096];
      int pos, nread;
      struct linux_dirent64 *de;
474

475 476 477 478 479
      while ((nread = syscall (SYS_getdents64, dir_fd, buf, sizeof(buf))) > 0)
        {
          for (pos = 0; pos < nread; pos += de->d_reclen)
            {
              de = (struct linux_dirent64 *)(buf + pos);
480

481 482 483
              fd = filename_to_fd (de->d_name);
              if (fd < 0 || fd == dir_fd)
                  continue;
484

485 486 487
              if ((res = cb (data, fd)) != 0)
                  break;
            }
488
        }
489 490

      close (dir_fd);
491
      return res;
492
    }
493 494 495 496 497

  /* If /proc is not mounted or not accessible we fall back to the old
   * rlimit trick */

#endif
498

499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548
#ifdef HAVE_SYS_RESOURCE_H
      
  if (getrlimit(RLIMIT_NOFILE, &rl) == 0 && rl.rlim_max != RLIM_INFINITY)
      open_max = rl.rlim_max;
  else
#endif
      open_max = sysconf (_SC_OPEN_MAX);

  for (fd = 0; fd < open_max; fd++)
      if ((res = cb (data, fd)) != 0)
          break;

  return res;
}
#endif

static gint
sane_dup2 (gint fd1, gint fd2)
{
  gint ret;

 retry:
  ret = dup2 (fd1, fd2);
  if (ret < 0 && errno == EINTR)
    goto retry;

  return ret;
}

static gint
sane_open (const char *path, gint mode)
{
  gint ret;

 retry:
  ret = open (path, mode);
  if (ret < 0 && errno == EINTR)
    goto retry;

  return ret;
}

enum
{
  CHILD_CHDIR_FAILED,
  CHILD_EXEC_FAILED,
  CHILD_DUP2_FAILED,
  CHILD_FORK_FAILED
};

549
static G_GNUC_NORETURN void
550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671
do_exec (gint                  child_err_report_fd,
         gint                  stdin_fd,
         gint                  stdout_fd,
         gint                  stderr_fd,
         const gchar          *working_directory,
         gchar               **argv,
         gchar               **envp,
         gboolean              close_descriptors,
         gboolean              search_path,
         gboolean              search_path_from_envp,
         gboolean              stdout_to_null,
         gboolean              stderr_to_null,
         gboolean              child_inherits_stdin,
         gboolean              file_and_argv_zero,
         GSpawnChildSetupFunc  child_setup,
         gpointer              user_data)
{
  if (working_directory && chdir (working_directory) < 0)
    write_err_and_exit (child_err_report_fd,
                        CHILD_CHDIR_FAILED);

  /* Close all file descriptors but stdin stdout and stderr as
   * soon as we exec. Note that this includes
   * child_err_report_fd, which keeps the parent from blocking
   * forever on the other end of that pipe.
   */
  if (close_descriptors)
    {
      fdwalk (set_cloexec, GINT_TO_POINTER(3));
    }
  else
    {
      /* We need to do child_err_report_fd anyway */
      set_cloexec (GINT_TO_POINTER(0), child_err_report_fd);
    }
  
  /* Redirect pipes as required */
  
  if (stdin_fd >= 0)
    {
      /* dup2 can't actually fail here I don't think */
          
      if (sane_dup2 (stdin_fd, 0) < 0)
        write_err_and_exit (child_err_report_fd,
                            CHILD_DUP2_FAILED);

      /* ignore this if it doesn't work */
      close_and_invalidate (&stdin_fd);
    }
  else if (!child_inherits_stdin)
    {
      /* Keep process from blocking on a read of stdin */
      gint read_null = open ("/dev/null", O_RDONLY);
      g_assert (read_null != -1);
      sane_dup2 (read_null, 0);
      close_and_invalidate (&read_null);
    }

  if (stdout_fd >= 0)
    {
      /* dup2 can't actually fail here I don't think */
          
      if (sane_dup2 (stdout_fd, 1) < 0)
        write_err_and_exit (child_err_report_fd,
                            CHILD_DUP2_FAILED);

      /* ignore this if it doesn't work */
      close_and_invalidate (&stdout_fd);
    }
  else if (stdout_to_null)
    {
      gint write_null = sane_open ("/dev/null", O_WRONLY);
      g_assert (write_null != -1);
      sane_dup2 (write_null, 1);
      close_and_invalidate (&write_null);
    }

  if (stderr_fd >= 0)
    {
      /* dup2 can't actually fail here I don't think */
          
      if (sane_dup2 (stderr_fd, 2) < 0)
        write_err_and_exit (child_err_report_fd,
                            CHILD_DUP2_FAILED);

      /* ignore this if it doesn't work */
      close_and_invalidate (&stderr_fd);
    }
  else if (stderr_to_null)
    {
      gint write_null = sane_open ("/dev/null", O_WRONLY);
      sane_dup2 (write_null, 2);
      close_and_invalidate (&write_null);
    }
  
  /* Call user function just before we exec */
  if (child_setup)
    {
      (* child_setup) (user_data);
    }

  g_execute (argv[0],
             file_and_argv_zero ? argv + 1 : argv,
             envp, search_path, search_path_from_envp);

  /* Exec failed */
  write_err_and_exit (child_err_report_fd,
                      CHILD_EXEC_FAILED);
}

static gboolean
read_ints (int      fd,
           gint*    buf,
           gint     n_ints_in_buf,    
           gint    *n_ints_read,
           gint     timeout,
           GPollFD *cancellable_pollfd,
           GError **error)
{
  gsize bytes = 0;
  GPollFD pollfds[2];
  guint n_pollfds;
672
  gint64 start_time = 0;
673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814

  if (timeout >= 0 || cancellable_pollfd != NULL)
    {
      if (fd_set_nonblocking(fd) < 0)
        {
          int errsv = errno;
          g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
                       _("Failed to set pipe nonblocking: %s"), g_strerror (errsv));
          return FALSE;
        }

      pollfds[0].fd = fd;
      pollfds[0].events = G_IO_IN | G_IO_HUP | G_IO_ERR;
      n_pollfds = 1;

      if (cancellable_pollfd != NULL)
        {
          pollfds[1] = *cancellable_pollfd;
          n_pollfds = 2;
        }
    }
  else
    n_pollfds = 0;

  if (timeout >= 0)
    start_time = g_get_monotonic_time ();

  while (TRUE)
    {
      gssize chunk;    

      if (bytes >= sizeof(gint)*2)
        break; /* give up, who knows what happened, should not be
                * possible.
                */
          
    again:
      if (n_pollfds != 0)
        {
          int r;

          pollfds[0].revents = pollfds[1].revents = 0;

          r = g_poll (pollfds, n_pollfds, timeout);

          /* Update timeout */
          if (timeout >= 0)
            {
              timeout -= (g_get_monotonic_time () - start_time) / 1000;
              if (timeout < 0)
                timeout = 0;
            }

          if (r < 0 && errno == EINTR)
            goto again;
          if (r < 0)
            {
              int errsv = errno;
              g_set_error (error, G_SPAWN_ERROR, G_SPAWN_ERROR_FAILED,
                           _("poll error: %s"), g_strerror (errsv));
              return FALSE;
            }
          if (r == 0)
            {
              g_set_error_literal (error, G_SPAWN_ERROR, VTE_SPAWN_ERROR_TIMED_OUT,
                                   _("Operation timed out"));
              return FALSE;
            }

          /* If the passed-in poll FD becomes readable, that's the signal
           * to cancel the operation. We do NOT actually read from its FD!
           */
          if (n_pollfds == 2 && pollfds[1].revents)
            {
              g_set_error_literal (error, G_SPAWN_ERROR, VTE_SPAWN_ERROR_CANCELLED,
                                   _("Operation was cancelled"));
              return FALSE;
            }

          /* Now we know we can try to read from the child */
        }

      chunk = read (fd,
                    ((gchar*)buf) + bytes,
                    sizeof(gint) * n_ints_in_buf - bytes);
      if (chunk < 0 && errno == EINTR)
        goto again;
          
      if (chunk < 0)
        {
          int errsv = errno;

          /* Some weird shit happened, bail out */
          g_set_error (error,
                       G_SPAWN_ERROR,
                       G_SPAWN_ERROR_FAILED,
                       _("Failed to read from child pipe (%s)"),
                       g_strerror (errsv));

          return FALSE;
        }
      else if (chunk == 0)
        break; /* EOF */
      else /* chunk > 0 */
	bytes += chunk;
    }

  *n_ints_read = (gint)(bytes / sizeof(gint));

  return TRUE;
}

static gboolean
fork_exec_with_pipes (gboolean              intermediate_child,
                      const gchar          *working_directory,
                      gchar               **argv,
                      gchar               **envp,
                      gboolean              close_descriptors,
                      gboolean              search_path,
                      gboolean              search_path_from_envp,
                      gboolean              stdout_to_null,
                      gboolean              stderr_to_null,
                      gboolean              child_inherits_stdin,
                      gboolean              file_and_argv_zero,
                      gboolean              cloexec_pipes,
                      GSpawnChildSetupFunc  child_setup,
                      gpointer              user_data,
                      GPid                 *child_pid,
                      gint                 *standard_input,
                      gint                 *standard_output,
                      gint                 *standard_error,
                      gint                  timeout,
                      GPollFD              *pollfd,
                      GError              **error)     
{
  GPid pid = -1;
  gint stdin_pipe[2] = { -1, -1 };
  gint stdout_pipe[2] = { -1, -1 };
  gint stderr_pipe[2] = { -1, -1 };
  gint child_err_report_pipe[2] = { -1, -1 };
  gint child_pid_report_pipe[2] = { -1, -1 };
  guint pipe_flags = cloexec_pipes ? FD_CLOEXEC : 0;
815 816 817

  g_assert(!intermediate_child);

818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870
  if (!g_unix_open_pipe (child_err_report_pipe, pipe_flags, error))
    return FALSE;

  if (standard_input && !g_unix_open_pipe (stdin_pipe, pipe_flags, error))
    goto cleanup_and_fail;
  
  if (standard_output && !g_unix_open_pipe (stdout_pipe, pipe_flags, error))
    goto cleanup_and_fail;

  if (standard_error && !g_unix_open_pipe (stderr_pipe, FD_CLOEXEC, error))
    goto cleanup_and_fail;

  pid = fork ();

  if (pid < 0)
    {
      int errsv = errno;

      g_set_error (error,
                   G_SPAWN_ERROR,
                   G_SPAWN_ERROR_FORK,
                   _("Failed to fork (%s)"),
                   g_strerror (errsv));

      goto cleanup_and_fail;
    }
  else if (pid == 0)
    {
      /* Immediate child. This may or may not be the child that
       * actually execs the new process.
       */

      /* Reset some signal handlers that we may use */
      signal (SIGCHLD, SIG_DFL);
      signal (SIGINT, SIG_DFL);
      signal (SIGTERM, SIG_DFL);
      signal (SIGHUP, SIG_DFL);
      
      /* Be sure we crash if the parent exits
       * and we write to the err_report_pipe
       */
      signal (SIGPIPE, SIG_DFL);

      /* Close the parent's end of the pipes;
       * not needed in the close_descriptors case,
       * though
       */
      close_and_invalidate (&child_err_report_pipe[0]);
      close_and_invalidate (&child_pid_report_pipe[0]);
      close_and_invalidate (&stdin_pipe[1]);
      close_and_invalidate (&stdout_pipe[0]);
      close_and_invalidate (&stderr_pipe[0]);
      
871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886
      do_exec (child_err_report_pipe[1],
               stdin_pipe[0],
               stdout_pipe[1],
               stderr_pipe[1],
               working_directory,
               argv,
               envp,
               close_descriptors,
               search_path,
               search_path_from_envp,
               stdout_to_null,
               stderr_to_null,
               child_inherits_stdin,
               file_and_argv_zero,
               child_setup,
               user_data);
887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
    }
  else
    {
      /* Parent */
      
      gint buf[2];
      gint n_ints = 0;    

      /* Close the uncared-about ends of the pipes */
      close_and_invalidate (&child_err_report_pipe[1]);
      close_and_invalidate (&child_pid_report_pipe[1]);
      close_and_invalidate (&stdin_pipe[0]);
      close_and_invalidate (&stdout_pipe[1]);
      close_and_invalidate (&stderr_pipe[1]);

      if (!read_ints (child_err_report_pipe[0],
                      buf, 2, &n_ints,
                      timeout, pollfd,
                      error))
        goto cleanup_and_fail;
        
      if (n_ints >= 2)
        {
          /* Error from the child. */

          switch (buf[0])
            {
            case CHILD_CHDIR_FAILED:
              g_set_error (error,
                           G_SPAWN_ERROR,
                           G_SPAWN_ERROR_CHDIR,
                           _("Failed to change to directory “%s” (%s)"),
                           working_directory,
                           g_strerror (buf[1]));

              break;
              
            case CHILD_EXEC_FAILED:
              g_set_error (error,
                           G_SPAWN_ERROR,
                           exec_err_to_g_error (buf[1]),
                           _("Failed to execute child process “%s” (%s)"),
                           argv[0],
                           g_strerror (buf[1]));

              break;
              
            case CHILD_DUP2_FAILED:
              g_set_error (error,
                           G_SPAWN_ERROR,
                           G_SPAWN_ERROR_FAILED,
                           _("Failed to redirect output or input of child process (%s)"),
                           g_strerror (buf[1]));

              break;

            case CHILD_FORK_FAILED:
              g_set_error (error,
                           G_SPAWN_ERROR,
                           G_SPAWN_ERROR_FORK,
                           _("Failed to fork child process (%s)"),
                           g_strerror (buf[1]));
              break;
              
            default:
              g_set_error (error,
                           G_SPAWN_ERROR,
                           G_SPAWN_ERROR_FAILED,
                           _("Unknown error executing child process “%s”"),
                           argv[0]);
              break;
            }

          goto cleanup_and_fail;
        }

      /* Success against all odds! return the information */
      close_and_invalidate (&child_err_report_pipe[0]);
      close_and_invalidate (&child_pid_report_pipe[0]);
 
      if (child_pid)
        *child_pid = pid;

      if (standard_input)
        *standard_input = stdin_pipe[1];
      if (standard_output)
        *standard_output = stdout_pipe[0];
      if (standard_error)
        *standard_error = stderr_pipe[0];
      
      return TRUE;
    }

 cleanup_and_fail:

  /* There was an error from the Child, reap the child to avoid it being
     a zombie.
   */

  if (pid > 0)
    {
      vte_reaper_add_child(pid);
     }

  close_and_invalidate (&child_err_report_pipe[0]);
  close_and_invalidate (&child_err_report_pipe[1]);
  close_and_invalidate (&child_pid_report_pipe[0]);
  close_and_invalidate (&child_pid_report_pipe[1]);
  close_and_invalidate (&stdin_pipe[0]);
  close_and_invalidate (&stdin_pipe[1]);
  close_and_invalidate (&stdout_pipe[0]);
  close_and_invalidate (&stdout_pipe[1]);
  close_and_invalidate (&stderr_pipe[0]);
  close_and_invalidate (&stderr_pipe[1]);

  return FALSE;
}

/* Based on execvp from GNU C Library */

static void
script_execute (const gchar *file,
                gchar      **argv,
                gchar      **envp)
{
  /* Count the arguments.  */
  int argc = 0;
  while (argv[argc])
    ++argc;
  
  /* Construct an argument list for the shell.  */
  {
    gchar **new_argv;

    new_argv = g_new0 (gchar*, argc + 2); /* /bin/sh and NULL */
    
    new_argv[0] = (char *) "/bin/sh";
    new_argv[1] = (char *) file;
    while (argc > 0)
      {
	new_argv[argc + 1] = argv[argc];
	--argc;
      }

    /* Execute the shell. */
    if (envp)
      execve (new_argv[0], new_argv, envp);
    else
      execv (new_argv[0], new_argv);
    
    g_free (new_argv);
  }
}

static gint
g_execute (const gchar *file,
           gchar      **argv,
           gchar      **envp,
           gboolean     search_path,
           gboolean     search_path_from_envp)
{
  if (*file == '\0')
    {
      /* We check the simple case first. */
      errno = ENOENT;
      return -1;
    }

  if (!(search_path || search_path_from_envp) || strchr (file, '/') != NULL)
    {
      /* Don't search when it contains a slash. */
      if (envp)
        execve (file, argv, envp);
      else
        execv (file, argv);
      
      if (errno == ENOEXEC)
	script_execute (file, argv, envp);
    }
  else
    {
      gboolean got_eacces = 0;
      const gchar *path, *p;
      gchar *name, *freeme;
      gsize len;
      gsize pathlen;

      path = NULL;
      if (search_path_from_envp)
        path = g_environ_getenv (envp, "PATH");
      if (search_path && path == NULL)
        path = g_getenv ("PATH");

      if (path == NULL)
	{
	  /* There is no 'PATH' in the environment.  The default
	   * search path in libc is the current directory followed by
	   * the path 'confstr' returns for '_CS_PATH'.
           */

          /* In GLib we put . last, for security, and don't use the
           * unportable confstr(); UNIX98 does not actually specify
           * what to search if PATH is unset. POSIX may, dunno.
           */
          
          path = "/bin:/usr/bin:.";
	}

      len = strlen (file) + 1;
      pathlen = strlen (path);
      freeme = name = (char*)g_malloc (pathlen + len + 1);
      
      /* Copy the file name at the top, including '\0'  */
      memcpy (name + pathlen + 1, file, len);
      name = name + pathlen;
      /* And add the slash before the filename  */
      *name = '/';

      p = path;
      do
	{
	  char *startp;

	  path = p;
1111
	  p = strchrnul (path, ':');
1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185

	  if (p == path)
	    /* Two adjacent colons, or a colon at the beginning or the end
             * of 'PATH' means to search the current directory.
             */
	    startp = name + 1;
	  else
            startp = (char*)memcpy (name - (p - path), path, p - path);

	  /* Try to execute this name.  If it works, execv will not return.  */
          if (envp)
            execve (startp, argv, envp);
          else
            execv (startp, argv);
          
	  if (errno == ENOEXEC)
	    script_execute (startp, argv, envp);

	  switch (errno)
	    {
	    case EACCES:
	      /* Record the we got a 'Permission denied' error.  If we end
               * up finding no executable we can use, we want to diagnose
               * that we did find one but were denied access.
               */
	      got_eacces = TRUE;

              /* FALL THRU */
              
	    case ENOENT:
#ifdef ESTALE
	    case ESTALE:
#endif
#ifdef ENOTDIR
	    case ENOTDIR:
#endif
	      /* Those errors indicate the file is missing or not executable
               * by us, in which case we want to just try the next path
               * directory.
               */
	      break;

	    case ENODEV:
	    case ETIMEDOUT:
	      /* Some strange filesystems like AFS return even
	       * stranger error numbers.  They cannot reasonably mean anything
	       * else so ignore those, too.
	       */
	      break;

	    default:
	      /* Some other error means we found an executable file, but
               * something went wrong executing it; return the error to our
               * caller.
               */
              g_free (freeme);
	      return -1;
	    }
	}
      while (*p++ != '\0');

      /* We tried every element and none of them worked.  */
      if (got_eacces)
	/* At least one failure was due to permissions, so report that
         * error.
         */
        errno = EACCES;

      g_free (freeme);
    }

  /* Return the error from the last attempt (probably ENOENT).  */
  return -1;
}