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/* pressure-vessel-wrap — run a program in a container that protects $HOME,
 * optionally using a Flatpak-style runtime.
 *
 * Contains code taken from Flatpak.
 *
 * Copyright © 2014-2019 Red Hat, Inc
 * Copyright © 2017-2019 Collabora Ltd.
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 * This program 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.
 *
 * This 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 this library. If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"
#include "subprojects/libglnx/config.h"

#include <glib.h>
#include <glib/gstdio.h>
#include <gio/gio.h>

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#include <locale.h>
#include "glib-backports.h"
#include "flatpak-bwrap-private.h"
#include "flatpak-run-private.h"
#include "flatpak-utils-private.h"
#include "utils.h"
#include "wrap-interactive.h"
/*
 * Supported Debian-style multiarch tuples
 */
static const char * const multiarch_tuples[] =
{
  "x86_64-linux-gnu",
  "i386-linux-gnu"
};

/*
 * Directories other than /usr/lib that we must search for loadable
 * modules, in the same order as multiarch_tuples
 */
static const char * const libquals[] =
{
  "lib64",
  "lib32"
};

static gchar *
find_executable_dir (GError **error)
{
  g_autofree gchar *target = glnx_readlinkat_malloc (-1, "/proc/self/exe",
                                                     NULL, error);

  if (target == NULL)
    return glnx_prefix_error_null (error, "Unable to resolve /proc/self/exe");

  return g_path_get_dirname (target);
}

static void
search_path_append (GString *search_path,
                    const gchar *item)
{
  if (item == NULL || item[0] == '\0')
    return;

  if (search_path->len != 0)
    g_string_append (search_path, ":");

  g_string_append (search_path, item);
}

static gchar *
find_bwrap (const char *tools_dir)
{
  static const char * const flatpak_libexecdirs[] =
  {
    "/usr/local/libexec",
    "/usr/libexec",
    "/usr/lib/flatpak"
  };
  const char *tmp;
  g_autofree gchar *candidate = NULL;
  g_autofree gchar *dirname = NULL;
  gsize i;

  g_return_val_if_fail (tools_dir != NULL, NULL);

  tmp = g_getenv ("BWRAP");

  if (tmp != NULL)
    return g_strdup (tmp);

  candidate = g_find_program_in_path ("bwrap");

  if (candidate != NULL)
    return g_steal_pointer (&candidate);

  for (i = 0; i < G_N_ELEMENTS (flatpak_libexecdirs); i++)
    {
      candidate = g_build_filename (flatpak_libexecdirs[i],
                                    "flatpak-bwrap", NULL);

      if (g_file_test (candidate, G_FILE_TEST_IS_EXECUTABLE))
        return g_steal_pointer (&candidate);
      else
        g_clear_pointer (&candidate, g_free);
    }

  candidate = g_build_filename (tools_dir, "bwrap", NULL);

  if (g_file_test (candidate, G_FILE_TEST_IS_EXECUTABLE))
    return g_steal_pointer (&candidate);
  else
    g_clear_pointer (&candidate, g_free);

  return NULL;
}

static gchar *
check_bwrap (const char *tools_dir)
{
  g_autoptr(GError) local_error = NULL;
  GError **error = &local_error;
  g_autofree gchar *bwrap_executable = find_bwrap (tools_dir);
  const char *bwrap_test_argv[] =
  {
    NULL,
    "--bind", "/", "/",
    "true",
    NULL
  };

  g_return_val_if_fail (tools_dir != NULL, NULL);

  if (bwrap_executable == NULL)
    {
      g_warning ("Cannot find bwrap");
    }
  else
    {
      int exit_status;
      g_autofree gchar *child_stdout = NULL;
      g_autofree gchar *child_stderr = NULL;

      bwrap_test_argv[0] = bwrap_executable;

      if (!g_spawn_sync (NULL,  /* cwd */
                         (gchar **) bwrap_test_argv,
                         NULL,  /* environ */
                         G_SPAWN_DEFAULT,
                         NULL, NULL,    /* child setup */
                         &child_stdout,
                         &child_stderr,
                         &exit_status,
                         error))
        {
          g_warning ("Cannot run bwrap: %s", local_error->message);
          g_clear_error (&local_error);
        }
      else if (exit_status != 0)
        {
          g_warning ("Cannot run bwrap: exit status %d", exit_status);

          if (child_stdout != NULL && child_stdout[0] != '\0')
            g_warning ("Output:\n%s", child_stdout);

          if (child_stderr != NULL && child_stderr[0] != '\0')
            g_warning ("Diagnostic output:\n%s", child_stderr);
        }
      else
        {
          return g_steal_pointer (&bwrap_executable);
        }
    }

  return NULL;
}

static gchar *
capture_output (const char * const * argv,
                GError **error)
{
  gsize len;
  gint exit_status;
  g_autofree gchar *output = NULL;
  g_autofree gchar *errors = NULL;
  gsize i;
  g_autoptr(GString) command = g_string_new ("");

  for (i = 0; argv[i] != NULL; i++)
    {
      g_autofree gchar *quoted = g_shell_quote (argv[i]);

      g_string_append_printf (command, " %s", quoted);
    }

  g_debug ("run:%s", command->str);

  if (!g_spawn_sync (NULL,  /* cwd */
                     (char **) argv,
                     NULL,  /* env */
                     G_SPAWN_SEARCH_PATH,
                     NULL, NULL,    /* child setup */
                     &output,
                     &errors,
                     &exit_status,
                     error))
    return NULL;

  g_printerr ("%s", errors);

  if (!g_spawn_check_exit_status (exit_status, error))
    return NULL;

  len = strlen (output);

  /* Emulate shell $() */
  if (len > 0 && output[len - 1] == '\n')
    output[len - 1] = '\0';

  return g_steal_pointer (&output);
}

static gboolean
try_bind_dri (FlatpakBwrap *bwrap,
              FlatpakBwrap *mount_runtime_on_scratch,
              const char *overrides,
              const char *scratch,
              const char *tool_path,
              const char *libdir,
              const char *libdir_on_host,
              GError **error)
{
  g_autofree gchar *dri = g_build_filename (libdir, "dri", NULL);
  g_autofree gchar *s2tc = g_build_filename (libdir, "libtxc_dxtn.so", NULL);

  /* mount_runtime_on_scratch can't own any fds, because if it did,
   * flatpak_bwrap_append_bwrap() would steal them. */
  g_return_val_if_fail (mount_runtime_on_scratch->fds == NULL
                        || mount_runtime_on_scratch->fds->len == 0,
                        FALSE);

  if (g_file_test (dri, G_FILE_TEST_IS_DIR))
    {
      g_autoptr(FlatpakBwrap) temp_bwrap = NULL;
      g_autofree gchar *expr = NULL;
      g_autofree gchar *host_dri = NULL;
      g_autofree gchar *dest_dri = NULL;

      expr = g_strdup_printf ("only-dependencies:if-exists:path-match:%s/dri/*.so",
                              libdir);

      temp_bwrap = flatpak_bwrap_new (NULL);
      g_warn_if_fail (mount_runtime_on_scratch->fds == NULL
                      || mount_runtime_on_scratch->fds->len == 0);
      flatpak_bwrap_append_bwrap (temp_bwrap, mount_runtime_on_scratch);
      flatpak_bwrap_add_args (temp_bwrap,
                              tool_path,
                              "--container", scratch,
                              "--link-target", "/run/host",
                              "--dest", libdir_on_host,
                              "--provider", "/",
                              expr,
                              NULL);
      flatpak_bwrap_finish (temp_bwrap);

      if (!pv_bwrap_run_sync (temp_bwrap, NULL, error))
        return FALSE;

      g_clear_pointer (&temp_bwrap, flatpak_bwrap_free);

      host_dri = g_build_filename ("/run/host", libdir, "dri", NULL);
      dest_dri = g_build_filename (libdir_on_host, "dri", NULL);
      temp_bwrap = flatpak_bwrap_new (NULL);
      flatpak_bwrap_add_args (temp_bwrap,
                              bwrap->argv->pdata[0],
                              "--ro-bind", "/", "/",
                              "--tmpfs", "/run",
                              "--ro-bind", "/", "/run/host",
                              "--bind", overrides, overrides,
                              "sh", "-c",
                              "ln -fns \"$1\"/* \"$2\"",
                              "sh",   /* $0 */
                              host_dri,
                              dest_dri,
                              NULL);
      flatpak_bwrap_finish (temp_bwrap);

      if (!pv_bwrap_run_sync (temp_bwrap, NULL, error))
        return FALSE;
    }

  if (g_file_test (s2tc, G_FILE_TEST_EXISTS))
    {
      g_autoptr(FlatpakBwrap) temp_bwrap = NULL;
      g_autofree gchar *expr = NULL;

      expr = g_strdup_printf ("path-match:%s", s2tc);
      temp_bwrap = flatpak_bwrap_new (NULL);
      g_warn_if_fail (mount_runtime_on_scratch->fds == NULL
                      || mount_runtime_on_scratch->fds->len == 0);
      flatpak_bwrap_append_bwrap (temp_bwrap, mount_runtime_on_scratch);
      flatpak_bwrap_add_args (temp_bwrap,
                              tool_path,
                              "--container", scratch,
                              "--link-target", "/run/host",
                              "--dest", libdir_on_host,
                              "--provider", "/",
                              expr,
                              NULL);
      flatpak_bwrap_finish (temp_bwrap);

      if (!pv_bwrap_run_sync (temp_bwrap, NULL, error))
/*
 * Try to make sure we have all the locales we need, by running
 * the helper from steam-runtime-tools in the container. If this
 * fails, it isn't fatal - carry on anyway.
 *
 * @bwrap must be set up to have the same libc that we will be using
 * for the container.
 */
static void
ensure_locales (gboolean on_host,
                const char *tools_dir,
                FlatpakBwrap *bwrap,
                const char *overrides)
{
  g_autoptr(GError) local_error = NULL;
  g_autoptr(FlatpakBwrap) run_locale_gen = NULL;
  g_autofree gchar *locale_gen = NULL;
  g_autofree gchar *locales = g_build_filename (overrides, "locales", NULL);
  g_autoptr(GDir) dir = NULL;
  int exit_status;

  /* bwrap can't own any fds yet, because if it did,
   * flatpak_bwrap_append_bwrap() would steal them. */
  g_return_if_fail (bwrap->fds == NULL || bwrap->fds->len == 0);

  g_mkdir (locales, 0700);

  run_locale_gen = flatpak_bwrap_new (NULL);

  if (on_host)
    {
      locale_gen = g_build_filename (tools_dir,
                                     "pressure-vessel-locale-gen",
                                     NULL);

      flatpak_bwrap_add_args (run_locale_gen,
                              bwrap->argv->pdata[0],
                              "--ro-bind", "/", "/",
                              NULL);
      pv_bwrap_add_api_filesystems (run_locale_gen);
      flatpak_bwrap_add_args (run_locale_gen,
                              "--bind", locales, locales,
                              "--chdir", locales,
                              locale_gen,
                              "--verbose",
                              NULL);
    }
  else
    {
      locale_gen = g_build_filename ("/run/host/tools",
                                     "pressure-vessel-locale-gen",
                                     NULL);

      flatpak_bwrap_append_bwrap (run_locale_gen, bwrap);
      pv_bwrap_copy_tree (run_locale_gen, overrides, "/overrides");

      if (!flatpak_bwrap_bundle_args (run_locale_gen, 1, -1, FALSE,
                                      &local_error))
        {
          g_warning ("Unable to set up locale-gen command: %s",
                     local_error->message);
          g_clear_error (&local_error);
        }

      flatpak_bwrap_add_args (run_locale_gen,
                              "--ro-bind", tools_dir, "/run/host/tools",
                              "--bind", locales, "/overrides/locales",
                              "--chdir", "/overrides/locales",
                              locale_gen,
                              "--verbose",
                              NULL);
    }

  flatpak_bwrap_finish (run_locale_gen);

  /* locale-gen exits 72 (EX_OSFILE) if it had to correct for
   * missing locales at OS level. This is not an error. */
  if (!pv_bwrap_run_sync (run_locale_gen, &exit_status, &local_error))
    {
      if (exit_status == EX_OSFILE)
        g_debug ("pressure-vessel-locale-gen created missing locales");
      else
        g_warning ("Unable to generate locales: %s", local_error->message);

      g_clear_error (&local_error);
    }
  else
    {
      g_debug ("No locales generated");
    }

  dir = g_dir_open (locales, 0, NULL);

  /* If the directory is not empty, make it the container's LOCPATH */
  if (dir != NULL && g_dir_read_name (dir) != NULL)
    {
      g_autoptr(GString) locpath = NULL;

      g_debug ("%s is non-empty", locales);

      locpath = g_string_new ("/overrides/locales");
      search_path_append (locpath, g_getenv ("LOCPATH"));
      flatpak_bwrap_add_args (bwrap,
                              "--setenv", "LOCPATH", locpath->str,
                              NULL);
    }
  else
    {
      g_debug ("%s is empty", locales);
    }
}

static gboolean
bind_runtime (FlatpakBwrap *bwrap,
              const char *tools_dir,
              const char *runtime,
              const char *overrides,
              const char *scratch,
              GError **error)
{
  static const char * const bind_mutable[] =
  {
    "etc",
    "var/cache",
    "var/lib"
  };
  static const char * const dont_bind[] =
  {
    "/etc/group",
    "/etc/passwd",
    "/etc/host.conf",
    "/etc/hosts",
    "/etc/localtime",
    "/etc/machine-id",
    "/etc/resolv.conf",
    "/var/lib/dbus",
    "/var/lib/dhcp",
    "/var/lib/sudo",
    "/var/lib/urandom",
    NULL
  };
  g_autofree gchar *xrd = g_strdup_printf ("/run/user/%ld", (long) geteuid ());
  g_autofree gchar *usr = NULL;
  gsize i, j;
  const gchar *member;
  g_autoptr(GString) dri_path = g_string_new ("");
  gboolean any_architecture_works = FALSE;
  gboolean any_libc_from_host = FALSE;
  gboolean all_libc_from_host = TRUE;
  g_autofree gchar *localedef = NULL;

  g_return_val_if_fail (tools_dir != NULL, FALSE);
  g_return_val_if_fail (runtime != NULL, FALSE);
  g_return_val_if_fail (overrides != NULL, FALSE);
  g_return_val_if_fail (scratch != NULL, FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  usr = g_build_filename (runtime, "usr", NULL);

  if (!pv_bwrap_bind_usr (bwrap, runtime, "/", error))
    return FALSE;

  flatpak_bwrap_add_args (bwrap,
                          "--setenv", "XDG_RUNTIME_DIR", xrd,
                          "--tmpfs", "/run",
                          "--tmpfs", "/tmp",
                          "--tmpfs", "/var",
                          "--symlink", "../run", "/var/run",
                          NULL);

  for (i = 0; i < G_N_ELEMENTS (bind_mutable); i++)
    {
      g_autofree gchar *path = g_build_filename (runtime, bind_mutable[i],
                                                 NULL);
      g_autoptr(GDir) dir = NULL;

      dir = g_dir_open (path, 0, NULL);

      if (dir == NULL)
        continue;

      for (member = g_dir_read_name (dir);
           member != NULL;
           member = g_dir_read_name (dir))
        {
          g_autofree gchar *dest = g_build_filename ("/", bind_mutable[i],
                                                     member, NULL);
          g_autofree gchar *full = NULL;
          g_autofree gchar *target = NULL;

          if (g_strv_contains (dont_bind, dest))
            continue;

          full = g_build_filename (runtime, bind_mutable[i], member, NULL);
          target = glnx_readlinkat_malloc (-1, full, NULL, NULL);

          if (target != NULL)
            flatpak_bwrap_add_args (bwrap, "--symlink", target, dest, NULL);
          else
            flatpak_bwrap_add_args (bwrap, "--ro-bind", full, dest, NULL);
        }
    }

  if (g_file_test ("/etc/machine-id", G_FILE_TEST_EXISTS))
    {
      flatpak_bwrap_add_args (bwrap,
                              "--ro-bind", "/etc/machine-id", "/etc/machine-id",
                              "--symlink", "/etc/machine-id",
                              "/var/lib/dbus/machine-id",
                              NULL);
    }
  else if (g_file_test ("/var/lib/dbus/machine-id", G_FILE_TEST_EXISTS))
    {
      flatpak_bwrap_add_args (bwrap,
                              "--ro-bind", "/var/lib/dbus/machine-id",
                              "/etc/machine-id",
                              "--symlink", "/etc/machine-id",
                              "/var/lib/dbus/machine-id",
                              NULL);
    }

  if (g_file_test ("/etc/resolv.conf", G_FILE_TEST_EXISTS))
    flatpak_bwrap_add_args (bwrap,
                            "--ro-bind", "/etc/resolv.conf", "/etc/resolv.conf",
                            NULL);
  if (g_file_test ("/etc/host.conf", G_FILE_TEST_EXISTS))
    flatpak_bwrap_add_args (bwrap,
                            "--ro-bind", "/etc/host.conf", "/etc/host.conf",
                            NULL);
  if (g_file_test ("/etc/hosts", G_FILE_TEST_EXISTS))
    flatpak_bwrap_add_args (bwrap,
                            "--ro-bind", "/etc/hosts", "/etc/hosts",
                            NULL);

  /* TODO: Synthesize a passwd with only the user and nobody,
   * like Flatpak does? */
  if (g_file_test ("/etc/passwd", G_FILE_TEST_EXISTS))
    flatpak_bwrap_add_args (bwrap,
                            "--ro-bind", "/etc/passwd", "/etc/passwd",
                            NULL);
  if (g_file_test ("/etc/group", G_FILE_TEST_EXISTS))
    flatpak_bwrap_add_args (bwrap,
                            "--ro-bind", "/etc/group", "/etc/group",
                            NULL);

  for (i = 0; i < G_N_ELEMENTS (multiarch_tuples); i++)
    {
      g_autofree gchar *tool = g_strdup_printf ("%s-capsule-capture-libs",
                                                multiarch_tuples[i]);
      g_autofree gchar *tool_path = NULL;
      g_autofree gchar *ld_so = NULL;
      const gchar *argv[] = { NULL, "--print-ld.so", NULL };

      g_debug ("Checking for %s libraries...", multiarch_tuples[i]);

      tool_path = g_build_filename (tools_dir, tool, NULL);
      argv[0] = tool_path;

      /* This has the side-effect of testing whether we can run binaries
       * for this architecture on the host system. */
      ld_so = capture_output (argv, NULL);

      if (ld_so != NULL)
        {
          g_auto(GStrv) dirs = NULL;
          g_autoptr(FlatpakBwrap) mount_runtime_on_scratch = NULL;
          g_autoptr(FlatpakBwrap) temp_bwrap = NULL;
          g_autofree gchar *libdir_in_container = g_build_filename ("/overrides",
                                                                    "lib",
                                                                    multiarch_tuples[i],
                                                                    NULL);
          g_autofree gchar *libdir_on_host = g_build_filename (overrides, "lib",
                                                               multiarch_tuples[i],
                                                               NULL);
          g_autofree gchar *this_dri_path_on_host = g_build_filename (libdir_on_host,
                                                                      "dri", NULL);
          g_autofree gchar *this_dri_path_in_container = g_build_filename (libdir_in_container,
                                                                           "dri", NULL);
          g_autofree gchar *libc = NULL;
          g_autofree gchar *ld_so_in_runtime = NULL;
          temp_bwrap = flatpak_bwrap_new (NULL);
          flatpak_bwrap_add_args (temp_bwrap,
                                  bwrap->argv->pdata[0],
                                  NULL);

          if (!pv_bwrap_bind_usr (temp_bwrap, runtime, "/", error))
            return FALSE;

          flatpak_bwrap_add_args (temp_bwrap,
                                  "readlink", "-e", ld_so,
                                  NULL);
          flatpak_bwrap_finish (temp_bwrap);

          ld_so_in_runtime = capture_output ((const char * const *) temp_bwrap->argv->pdata,
                                             NULL);

          g_clear_pointer (&temp_bwrap, flatpak_bwrap_free);

          if (ld_so_in_runtime == NULL)
            {
              g_debug ("Container does not have %s so it cannot run "
                       "%s binaries", ld_so, multiarch_tuples[i]);
              continue;
            }

          any_architecture_works = TRUE;
          g_debug ("Container path: %s -> %s", ld_so, ld_so_in_runtime);

          search_path_append (dri_path, this_dri_path_in_container);

          g_mkdir_with_parents (libdir_on_host, 0755);
          g_mkdir_with_parents (this_dri_path_on_host, 0755);

          mount_runtime_on_scratch = flatpak_bwrap_new (NULL);
          flatpak_bwrap_add_args (mount_runtime_on_scratch,
                                  bwrap->argv->pdata[0],
                                  "--ro-bind", "/", "/",
                                  "--bind", overrides, overrides,
                                  "--tmpfs", scratch,
                                  NULL);
          if (!pv_bwrap_bind_usr (mount_runtime_on_scratch, runtime, scratch,
            return FALSE;

          temp_bwrap = flatpak_bwrap_new (NULL);
          /* mount_runtime_on_scratch can't own any fds, because if it did,
           * flatpak_bwrap_append_bwrap() would steal them. */
          g_warn_if_fail (mount_runtime_on_scratch->fds == NULL
                          || mount_runtime_on_scratch->fds->len == 0);
          flatpak_bwrap_append_bwrap (temp_bwrap, mount_runtime_on_scratch);
          flatpak_bwrap_add_args (temp_bwrap,
                                  tool_path,
                                  "--container", scratch,
                                  "--link-target", "/run/host",
                                  "--dest", libdir_on_host,
                                  "--provider", "/",
                                  "gl:",
                                  NULL);
          flatpak_bwrap_finish (temp_bwrap);

          if (!pv_bwrap_run_sync (temp_bwrap, NULL, error))
          g_clear_pointer (&temp_bwrap, flatpak_bwrap_free);

          libc = g_build_filename (libdir_on_host, "libc.so.6", NULL);

          /* If we are going to use the host system's libc6 (likely)
           * then we have to use its ld.so too. */
          if (g_file_test (libc, G_FILE_TEST_IS_SYMLINK))
            {
              g_autofree gchar *ld_so_in_host = NULL;
              g_debug ("Making host ld.so visible in container");

              ld_so_in_host = flatpak_canonicalize_filename (ld_so);
              g_debug ("Host path: %s -> %s", ld_so, ld_so_in_host);

              g_clear_pointer (&temp_bwrap, flatpak_bwrap_free);

              temp_bwrap = flatpak_bwrap_new (NULL);
              flatpak_bwrap_add_args (temp_bwrap,
              if (!pv_bwrap_bind_usr (temp_bwrap, runtime, "/", error))
                return FALSE;

              flatpak_bwrap_add_args (temp_bwrap,
                                      "readlink", "-f", ld_so,
                                      NULL);
              flatpak_bwrap_finish (temp_bwrap);

              g_debug ("Container path: %s -> %s", ld_so, ld_so_in_runtime);
              flatpak_bwrap_add_args (bwrap,
                                      "--ro-bind", ld_so_in_host,
                                      ld_so_in_runtime,
              /* Collect miscellaneous libraries that libc might dlopen.
               * At the moment this is just libidn2. */
              temp_bwrap = flatpak_bwrap_new (NULL);
              g_warn_if_fail (mount_runtime_on_scratch->fds == NULL
                              || mount_runtime_on_scratch->fds->len == 0);
              flatpak_bwrap_append_bwrap (temp_bwrap, mount_runtime_on_scratch);
              flatpak_bwrap_add_args (temp_bwrap,
                                      tool_path,
                                      "--container", scratch,
                                      "--link-target", "/run/host",
                                      "--dest", libdir_on_host,
                                      "--provider", "/",
                                      "if-exists:libidn2.so.0",
                                      NULL);
              flatpak_bwrap_finish (temp_bwrap);

              if (!pv_bwrap_run_sync (temp_bwrap, NULL, error))
                return FALSE;

              g_clear_pointer (&temp_bwrap, flatpak_bwrap_free);

              any_libc_from_host = TRUE;
            }
          else
            {
              all_libc_from_host = FALSE;
          /* /lib32 or /lib64 */
          libqual = libquals[i];
          dirs[0] = g_build_filename ("/lib", multiarch_tuples[i], NULL);
          dirs[1] = g_build_filename ("/usr", "lib", multiarch_tuples[i], NULL);
          dirs[2] = g_strdup ("/lib");
          dirs[3] = g_strdup ("/usr/lib");
          dirs[4] = g_build_filename ("/", libqual, NULL);
          dirs[5] = g_build_filename ("/usr", libqual, NULL);
              if (!try_bind_dri (bwrap, mount_runtime_on_scratch,
                                 overrides, scratch, tool_path, dirs[j],
                                 libdir_on_host, error))
                return FALSE;
            }
        }
      else
        {
          g_debug ("Cannot determine ld.so for %s", multiarch_tuples[i]);
        }
    }

  if (!any_architecture_works)
    {
      GString *archs = g_string_new ("");

      for (i = 0; i < G_N_ELEMENTS (multiarch_tuples); i++)
        {
          if (archs->len > 0)
            g_string_append (archs, ", ");

          g_string_append (archs, multiarch_tuples[i]);
        }

      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
                   "None of the supported CPU architectures are common to "
                   "the host system and the container (tried: %s)",
                   archs->str);
      g_string_free (archs, TRUE);
      return FALSE;
    }

  if (any_libc_from_host && !all_libc_from_host)
    {
      /*
       * This shouldn't happen. It would mean that there exist at least
       * two architectures (let's say aaa and bbb) for which we have:
       * host libc6:aaa < container libc6 < host libc6:bbb
       * (we know that the container's libc6:aaa and libc6:bbb are
       * constrained to be the same version because that's how multiarch
       * works).
       *
       * If the host system locales work OK with both the aaa and bbb
       * versions, let's assume they will also work with the intermediate
       * version from the container...
       */
      g_warning ("Using glibc from host system for some but not all "
                 "architectures! Arbitrarily using host locales.");
    }

  if (any_libc_from_host)
    {
      g_debug ("Making host locale data visible in container");

      if (g_file_test ("/usr/lib/locale", G_FILE_TEST_EXISTS))
        flatpak_bwrap_add_args (bwrap,
                                "--ro-bind", "/usr/lib/locale",
                                "/usr/lib/locale",
                                NULL);

      if (g_file_test ("/usr/share/i18n", G_FILE_TEST_EXISTS))
        flatpak_bwrap_add_args (bwrap,
                                "--ro-bind", "/usr/share/i18n",
                                "/usr/share/i18n",
                                NULL);

      localedef = g_find_program_in_path ("localedef");

      if (localedef == NULL)
        {
          g_warning ("Cannot find localedef in PATH");
        }
      else
        {
          g_autofree gchar *target = g_build_filename ("/run/host",
                                                       localedef, NULL);

          flatpak_bwrap_add_args (bwrap,
                                  "--symlink", target,
                                      "/overrides/bin/localedef",
                                  NULL);
        }
    }
  else
    {
      g_debug ("Using included locale data from container");
    }

  if (!pv_bwrap_bind_usr (bwrap, "/", "/run/host", error))
    return FALSE;

  ensure_locales (any_libc_from_host, tools_dir, bwrap, overrides);

  if (dri_path->len != 0)
      flatpak_bwrap_add_args (bwrap,
                              "--setenv", "LIBGL_DRIVERS_PATH", dri_path->str,
                              NULL);
  else
      flatpak_bwrap_add_args (bwrap,
                              "--unsetenv", "LIBGL_DRIVERS_PATH",
                              NULL);

  /* These can add data fds to @bwrap, so they must come last - after
   * other functions stop using @bwrap as a basis for their own bwrap
   * invocations with flatpak_bwrap_append_bwrap().
   * Otherwise, when flatpak_bwrap_append_bwrap() calls
   * flatpak_bwrap_steal_fds(), it will make the original FlatpakBwrap
   * unusable. */

  flatpak_run_add_wayland_args (bwrap);
  flatpak_run_add_x11_args (bwrap, TRUE);
  flatpak_run_add_pulseaudio_args (bwrap);
  flatpak_run_add_session_dbus_args (bwrap);
  flatpak_run_add_system_dbus_args (bwrap);
  pv_bwrap_copy_tree (bwrap, overrides, "/overrides");
  /* /etc/localtime and /etc/resolv.conf can not exist (or be symlinks to
   * non-existing targets), in which case we don't want to attempt to create
   * bogus symlinks or bind mounts, as that will cause flatpak run to fail.
   */
  if (g_file_test ("/etc/localtime", G_FILE_TEST_EXISTS))
    {
      g_autofree char *localtime = NULL;
      gboolean is_reachable = FALSE;
      g_autofree char *timezone = flatpak_get_timezone ();
      g_autofree char *timezone_content = g_strdup_printf ("%s\n", timezone);

      localtime = glnx_readlinkat_malloc (-1, "/etc/localtime", NULL, NULL);

      if (localtime != NULL)
        {
          g_autoptr(GFile) base_file = NULL;
          g_autoptr(GFile) target_file = NULL;
          g_autofree char *target_canonical = NULL;

          base_file = g_file_new_for_path ("/etc");
          target_file = g_file_resolve_relative_path (base_file, localtime);
          target_canonical = g_file_get_path (target_file);

          is_reachable = g_str_has_prefix (target_canonical, "/usr/");
        }

      if (is_reachable)
        {
          flatpak_bwrap_add_args (bwrap,
                                  "--symlink", localtime, "/etc/localtime",
                                  NULL);
        }
      else
        {
          flatpak_bwrap_add_args (bwrap,
                                  "--ro-bind", "/etc/localtime", "/etc/localtime",
                                  NULL);
        }

      flatpak_bwrap_add_args_data (bwrap, "timezone",
                                   timezone_content, -1, "/etc/timezone",
                                   NULL);
    }
/* Order matters here: root, steam and steambeta are or might be symlinks
 * to the root of the Steam installation, so we want to bind-mount their
 * targets before we deal with the rest. */
static const char * const steam_api_subdirs[] =
{
  "root", "steam", "steambeta", "bin", "bin32", "bin64", "sdk32", "sdk64",
};

static gboolean
use_fake_home (FlatpakBwrap *bwrap,
               const gchar *fake_home,
               GError **error)
{
  const gchar *real_home = g_get_home_dir ();
  g_autofree gchar *cache = g_build_filename (fake_home, ".cache", NULL);
  g_autofree gchar *cache2 = g_build_filename (fake_home, "cache", NULL);
  g_autofree gchar *tmp = g_build_filename (cache, "tmp", NULL);
  g_autofree gchar *config = g_build_filename (fake_home, ".config", NULL);
  g_autofree gchar *config2 = g_build_filename (fake_home, "config", NULL);
  g_autofree gchar *local = g_build_filename (fake_home, ".local", NULL);
  g_autofree gchar *data = g_build_filename (local, "share", NULL);
  g_autofree gchar *data2 = g_build_filename (fake_home, "data", NULL);
  g_autofree gchar *steam_pid = NULL;
  g_autofree gchar *steam_pipe = NULL;
  g_autoptr(GHashTable) mounted = NULL;
  gsize i;

  g_return_val_if_fail (bwrap != NULL, FALSE);
  g_return_val_if_fail (fake_home != NULL, FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  g_mkdir_with_parents (fake_home, 0700);
  g_mkdir_with_parents (cache, 0700);
  g_mkdir_with_parents (tmp, 0700);
  g_mkdir_with_parents (config, 0700);
  g_mkdir_with_parents (local, 0700);
  g_mkdir_with_parents (data, 0700);

  if (!g_file_test (cache2, G_FILE_TEST_EXISTS))
    {
      g_unlink (cache2);

      if (symlink (".cache", cache2) != 0)
        return glnx_throw_errno_prefix (error,
                                        "Unable to create symlink %s -> .cache",
                                        cache2);
    }

  if (!g_file_test (config2, G_FILE_TEST_EXISTS))
    {
      g_unlink (config2);

      if (symlink (".config", config2) != 0)
        return glnx_throw_errno_prefix (error,
                                        "Unable to create symlink %s -> .config",
                                        config2);
    }

  if (!g_file_test (data2, G_FILE_TEST_EXISTS))
    {
      g_unlink (data2);

      if (symlink (".local/share", data2) != 0)
        return glnx_throw_errno_prefix (error,
                                        "Unable to create symlink %s -> .local/share",
                                        data2);
    }

  flatpak_bwrap_add_args (bwrap,
                          "--bind", fake_home, real_home,
                          "--bind", fake_home, fake_home,
                          "--bind", tmp, "/var/tmp",
                          "--setenv", "XDG_CACHE_HOME", cache,
                          "--setenv", "XDG_CONFIG_HOME", config,
                          "--setenv", "XDG_DATA_HOME", data,
                          NULL);