glibc/posix/tst-spawn-chdir.c

/* Test the posix_spawn_file_actions_addchdir_np function.
   Copyright (C) 2018-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library 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 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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 the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <array_length.h>
#include <errno.h>
#include <fcntl.h>
#include <spawn.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <support/check.h>
#include <support/support.h>
#include <support/temp_file.h>
#include <support/test-driver.h>
#include <support/xstdio.h>
#include <support/xunistd.h>
#include <unistd.h>

/* Reads the file at PATH, which must consist of exactly one line.
   Removes the line terminator at the end of the file.  */
static char *
read_one_line (const char *path)
{
  FILE *fp = xfopen (path, "r");
  char *buffer = NULL;
  size_t length = 0;
  ssize_t ret = getline (&buffer, &length, fp);
  if (ferror (fp))
    FAIL_EXIT1 ("getline: %m");
  if (ret < 1)
    FAIL_EXIT1 ("getline returned %zd", ret);
  if (fgetc (fp) != EOF)
    FAIL_EXIT1 ("trailing bytes in %s", path);
  if (ferror (fp))
    FAIL_EXIT1 ("fgetc: %m");
  xfclose (fp);
  if (buffer[ret - 1] != '\n')
    FAIL_EXIT1 ("missing line terminator in %s", path);
  buffer[ret - 1] = 0;
  return buffer;
}

/* Return the path to the "pwd" program.  */
const char *
get_pwd_program (void)
{
  const char *const paths[] = { "/bin/pwd", "/usr/bin/pwd" };
  for (size_t i = 0; i < array_length (paths); ++i)
    if (access (paths[i], X_OK) == 0)
      return paths[i];
  FAIL_EXIT1 ("cannot find pwd program");
}

/* Adds chdir operations to ACTIONS, using PATH.  If DO_FCHDIR, use
   the open function and TMPFD to emulate chdir using fchdir.  */
static void
add_chdir (posix_spawn_file_actions_t *actions, const char *path,
           bool do_fchdir, int tmpfd)
{
  if (do_fchdir)
    {
      TEST_COMPARE (posix_spawn_file_actions_addopen
                    (actions, tmpfd, path, O_DIRECTORY | O_RDONLY, 0), 0);
      TEST_COMPARE (posix_spawn_file_actions_addfchdir_np
                    (actions, tmpfd), 0);
      TEST_COMPARE (posix_spawn_file_actions_addclose (actions, tmpfd), 0);
    }
  else
    TEST_COMPARE (posix_spawn_file_actions_addchdir_np (actions, path), 0);
}

static int
do_test (void)
{
  /* Directory for temporary file data.  Each subtest uses a numeric
     subdirectory.  */
  char *directory = support_create_temp_directory ("tst-spawn-chdir-");
  {
    /* Avoid symbolic links, to get more consistent behavior from the
       pwd command.  */
    char *tmp = realpath (directory, NULL);
    if (tmp == NULL)
      FAIL_EXIT1 ("realpath: %m");
    free (directory);
    directory = tmp;
  }

  char *original_cwd = get_current_dir_name ();
  if (original_cwd == NULL)
    FAIL_EXIT1 ("get_current_dir_name: %m");

  int iteration = 0;
  for (int do_spawnp = 0; do_spawnp < 2; ++do_spawnp)
    for (int do_overwrite = 0; do_overwrite < 2; ++do_overwrite)
      for (int do_fchdir = 0; do_fchdir < 2; ++do_fchdir)
        {
          /* This subtest does not make sense for fchdir.  */
          if (do_overwrite && do_fchdir)
            continue;

          ++iteration;
          if (test_verbose > 0)
            printf ("info: iteration=%d do_spawnp=%d do_overwrite=%d"
                    " do_fchdir=%d\n",
                    iteration, do_spawnp, do_overwrite, do_fchdir);

          /* The "pwd" program runs in this directory.  */
          char *iteration_directory = xasprintf ("%s/%d", directory, iteration);
          add_temp_file (iteration_directory);
          xmkdir (iteration_directory, 0777);

          /* This file receives output from "pwd".  */
          char *output_file_path
            = xasprintf ("%s/output-file", iteration_directory);
          add_temp_file (output_file_path);

          /* This subdirectory is used for chdir ordering checks.  */
          char *subdir_path = xasprintf ("%s/subdir", iteration_directory);
          add_temp_file (subdir_path);
          xmkdir (subdir_path, 0777);

          /* Also used for checking the order of actions.  */
          char *probe_file_path
            = xasprintf ("%s/subdir/probe-file", iteration_directory);
          add_temp_file (probe_file_path);
          TEST_COMPARE (access (probe_file_path, F_OK), -1);
          TEST_COMPARE (errno, ENOENT);

          /* This symbolic link is used in a relative path with
             posix_spawn.  */
          char *pwd_symlink_path
            = xasprintf ("%s/subdir/pwd-symlink", iteration_directory);
          xsymlink (get_pwd_program (), pwd_symlink_path);
          add_temp_file (pwd_symlink_path);

          posix_spawn_file_actions_t actions;
          TEST_COMPARE (posix_spawn_file_actions_init (&actions), 0);
          add_chdir (&actions, subdir_path, do_fchdir, 4);
          TEST_COMPARE (posix_spawn_file_actions_addopen
                        (&actions, 3, /* Arbitrary unused descriptor.  */
                         "probe-file",
                         O_WRONLY | O_CREAT | O_EXCL, 0777), 0);
          TEST_COMPARE (posix_spawn_file_actions_addclose (&actions, 3), 0);
          /* Run the actual in iteration_directory.  */
          add_chdir (&actions, "..", do_fchdir, 5);
          TEST_COMPARE (posix_spawn_file_actions_addopen
                        (&actions, STDOUT_FILENO, "output-file",
                         O_WRONLY | O_CREAT | O_EXCL, 0777), 0);

          /* Check that posix_spawn_file_actions_addchdir_np made a copy
             of the path.  */
          if (do_overwrite)
            subdir_path[0] = '\0';

          char *const argv[] = { (char *) "pwd", NULL };
          char *const envp[] = { NULL } ;
          pid_t pid;
          if (do_spawnp)
            TEST_COMPARE (posix_spawnp (&pid, "pwd", &actions,
                                        NULL, argv, envp), 0);
          else
            TEST_COMPARE (posix_spawn (&pid, "subdir/pwd-symlink", &actions,
                                       NULL, argv, envp), 0);
          TEST_VERIFY (pid > 0);
          int status;
          xwaitpid (pid, &status, 0);
          TEST_COMPARE (status, 0);

          /* Check that the current directory did not change.  */
          {
            char *cwd = get_current_dir_name ();
            if (cwd == NULL)
              FAIL_EXIT1 ("get_current_dir_name: %m");
            TEST_COMPARE_BLOB (original_cwd, strlen (original_cwd),
                               cwd, strlen (cwd));
            free (cwd);
          }


          /* Check the output from "pwd".  */
          {
            char *pwd = read_one_line (output_file_path);
            TEST_COMPARE_BLOB (iteration_directory, strlen (iteration_directory),
                               pwd, strlen (pwd));
            free (pwd);
          }

          /* This file must now exist.  */
          TEST_COMPARE (access (probe_file_path, F_OK), 0);

          TEST_COMPARE (posix_spawn_file_actions_destroy (&actions), 0);
          free (pwd_symlink_path);
          free (probe_file_path);
          free (subdir_path);
          free (output_file_path);
        }

  free (directory);

  return 0;
}

#include <support/test-driver.c>