/*
 * Copyright (C) 2008 Red Hat, Inc.
 *
 * This 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 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, write to the
 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Author: David Zeuthen <davidz@redhat.com>
 */

#include "polkitbackendcommon.h"

static void
utils_child_watch_from_release_cb (GPid     pid,
                                   gint     status,
                                   gpointer user_data)
{
}

static void
utils_spawn_data_free (UtilsSpawnData *data)
{
  if (data->timeout_source != NULL)
    {
      g_source_destroy (data->timeout_source);
      data->timeout_source = NULL;
    }

  /* Nuke the child, if necessary */
  if (data->child_watch_source != NULL)
    {
      g_source_destroy (data->child_watch_source);
      data->child_watch_source = NULL;
    }

  if (data->child_pid != 0)
    {
      GSource *source;
      kill (data->child_pid, SIGTERM);
      /* OK, we need to reap for the child ourselves - we don't want
       * to use waitpid() because that might block the calling
       * thread (the child might handle SIGTERM and use several
       * seconds for cleanup/rollback).
       *
       * So we use GChildWatch instead.
       *
       * Avoid taking a references to ourselves. but note that we need
       * to pass the GSource so we can nuke it once handled.
       */
      source = g_child_watch_source_new (data->child_pid);
      g_source_set_callback (source,
                             (GSourceFunc) utils_child_watch_from_release_cb,
                             source,
                             (GDestroyNotify) g_source_destroy);
      g_source_attach (source, data->main_context);
      g_source_unref (source);
      data->child_pid = 0;
    }

  if (data->child_stdout != NULL)
    {
      g_string_free (data->child_stdout, TRUE);
      data->child_stdout = NULL;
    }

  if (data->child_stderr != NULL)
    {
      g_string_free (data->child_stderr, TRUE);
      data->child_stderr = NULL;
    }

  if (data->child_stdout_channel != NULL)
    {
      g_io_channel_unref (data->child_stdout_channel);
      data->child_stdout_channel = NULL;
    }
  if (data->child_stderr_channel != NULL)
    {
      g_io_channel_unref (data->child_stderr_channel);
      data->child_stderr_channel = NULL;
    }

  if (data->child_stdout_source != NULL)
    {
      g_source_destroy (data->child_stdout_source);
      data->child_stdout_source = NULL;
    }
  if (data->child_stderr_source != NULL)
    {
      g_source_destroy (data->child_stderr_source);
      data->child_stderr_source = NULL;
    }

  if (data->child_stdout_fd != -1)
    {
      g_warn_if_fail (close (data->child_stdout_fd) == 0);
      data->child_stdout_fd = -1;
    }
  if (data->child_stderr_fd != -1)
    {
      g_warn_if_fail (close (data->child_stderr_fd) == 0);
      data->child_stderr_fd = -1;
    }

  if (data->cancellable_handler_id > 0)
    {
      g_cancellable_disconnect (data->cancellable, data->cancellable_handler_id);
      data->cancellable_handler_id = 0;
    }

  if (data->main_context != NULL)
    g_main_context_unref (data->main_context);

  if (data->cancellable != NULL)
    g_object_unref (data->cancellable);

  g_slice_free (UtilsSpawnData, data);
}

/* called in the thread where @cancellable was cancelled */
static void
utils_on_cancelled (GCancellable *cancellable,
                    gpointer      user_data)
{
  UtilsSpawnData *data = (UtilsSpawnData *)user_data;
  GError *error;

  error = NULL;
  g_warn_if_fail (g_cancellable_set_error_if_cancelled (cancellable, &error));
  g_simple_async_result_take_error (data->simple, error);
  g_simple_async_result_complete_in_idle (data->simple);
  g_object_unref (data->simple);
}

static gboolean
utils_timeout_cb (gpointer user_data)
{
  UtilsSpawnData *data = (UtilsSpawnData *)user_data;

  data->timed_out = TRUE;

  /* ok, timeout is history, make sure we don't free it in spawn_data_free() */
  data->timeout_source = NULL;

  /* we're done */
  g_simple_async_result_complete_in_idle (data->simple);
  g_object_unref (data->simple);

  return FALSE; /* remove source */
}

static void
utils_child_watch_cb (GPid     pid,
                      gint     status,
                      gpointer user_data)
{
  UtilsSpawnData *data = (UtilsSpawnData *)user_data;
  gchar *buf;
  gsize buf_size;

  if (g_io_channel_read_to_end (data->child_stdout_channel, &buf, &buf_size, NULL) == G_IO_STATUS_NORMAL)
    {
      g_string_append_len (data->child_stdout, buf, buf_size);
      g_free (buf);
    }
  if (g_io_channel_read_to_end (data->child_stderr_channel, &buf, &buf_size, NULL) == G_IO_STATUS_NORMAL)
    {
      g_string_append_len (data->child_stderr, buf, buf_size);
      g_free (buf);
    }

  data->exit_status = status;

  /* ok, child watch is history, make sure we don't free it in spawn_data_free() */
  data->child_pid = 0;
  data->child_watch_source = NULL;

  /* we're done */
  g_simple_async_result_complete_in_idle (data->simple);
  g_object_unref (data->simple);
}

static gboolean
utils_read_child_stderr (GIOChannel *channel,
                         GIOCondition condition,
                         gpointer user_data)
{
  UtilsSpawnData *data = (UtilsSpawnData *)user_data;
  gchar buf[1024];
  gsize bytes_read;

  g_io_channel_read_chars (channel, buf, sizeof buf, &bytes_read, NULL);
  g_string_append_len (data->child_stderr, buf, bytes_read);
  return TRUE;
}

static gboolean
utils_read_child_stdout (GIOChannel *channel,
                         GIOCondition condition,
                         gpointer user_data)
{
  UtilsSpawnData *data = (UtilsSpawnData *)user_data;
  gchar buf[1024];
  gsize bytes_read;

  g_io_channel_read_chars (channel, buf, sizeof buf, &bytes_read, NULL);
  g_string_append_len (data->child_stdout, buf, bytes_read);
  return TRUE;
}

void
polkit_backend_common_spawn (const gchar *const  *argv,
                             guint                timeout_seconds,
                             GCancellable        *cancellable,
                             GAsyncReadyCallback  callback,
                             gpointer             user_data)
{
  UtilsSpawnData *data;
  GError *error;

  data = g_slice_new0 (UtilsSpawnData);
  data->timeout_seconds = timeout_seconds;
  data->simple = g_simple_async_result_new (NULL,
                                            callback,
                                            user_data,
                                            (gpointer*)polkit_backend_common_spawn);
  data->main_context = g_main_context_get_thread_default ();
  if (data->main_context != NULL)
    g_main_context_ref (data->main_context);

  data->cancellable = cancellable != NULL ? (GCancellable*)g_object_ref (cancellable) : NULL;

  data->child_stdout = g_string_new (NULL);
  data->child_stderr = g_string_new (NULL);
  data->child_stdout_fd = -1;
  data->child_stderr_fd = -1;

  /* the life-cycle of UtilsSpawnData is tied to its GSimpleAsyncResult */
  g_simple_async_result_set_op_res_gpointer (data->simple, data, (GDestroyNotify) utils_spawn_data_free);

  error = NULL;
  if (data->cancellable != NULL)
    {
      /* could already be cancelled */
      error = NULL;
      if (g_cancellable_set_error_if_cancelled (data->cancellable, &error))
        {
          g_simple_async_result_take_error (data->simple, error);
          g_simple_async_result_complete_in_idle (data->simple);
          g_object_unref (data->simple);
          goto out;
        }

      data->cancellable_handler_id = g_cancellable_connect (data->cancellable,
                                                            G_CALLBACK (utils_on_cancelled),
                                                            data,
                                                            NULL);
    }

  error = NULL;
  if (!g_spawn_async_with_pipes (NULL, /* working directory */
                                 (gchar **) argv,
                                 NULL, /* envp */
                                 G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD,
                                 NULL, /* child_setup */
                                 NULL, /* child_setup's user_data */
                                 &(data->child_pid),
                                 NULL, /* gint *stdin_fd */
                                 &(data->child_stdout_fd),
                                 &(data->child_stderr_fd),
                                 &error))
    {
      g_prefix_error (&error, "Error spawning: ");
      g_simple_async_result_take_error (data->simple, error);
      g_simple_async_result_complete_in_idle (data->simple);
      g_object_unref (data->simple);
      goto out;
    }

  if (timeout_seconds > 0)
    {
      data->timeout_source = g_timeout_source_new_seconds (timeout_seconds);
      g_source_set_priority (data->timeout_source, G_PRIORITY_DEFAULT);
      g_source_set_callback (data->timeout_source, utils_timeout_cb, data, NULL);
      g_source_attach (data->timeout_source, data->main_context);
      g_source_unref (data->timeout_source);
    }

  data->child_watch_source = g_child_watch_source_new (data->child_pid);
  g_source_set_callback (data->child_watch_source, (GSourceFunc) utils_child_watch_cb, data, NULL);
  g_source_attach (data->child_watch_source, data->main_context);
  g_source_unref (data->child_watch_source);

  data->child_stdout_channel = g_io_channel_unix_new (data->child_stdout_fd);
  g_io_channel_set_flags (data->child_stdout_channel, G_IO_FLAG_NONBLOCK, NULL);
  data->child_stdout_source = g_io_create_watch (data->child_stdout_channel, G_IO_IN);
  g_source_set_callback (data->child_stdout_source, (GSourceFunc) utils_read_child_stdout, data, NULL);
  g_source_attach (data->child_stdout_source, data->main_context);
  g_source_unref (data->child_stdout_source);

  data->child_stderr_channel = g_io_channel_unix_new (data->child_stderr_fd);
  g_io_channel_set_flags (data->child_stderr_channel, G_IO_FLAG_NONBLOCK, NULL);
  data->child_stderr_source = g_io_create_watch (data->child_stderr_channel, G_IO_IN);
  g_source_set_callback (data->child_stderr_source, (GSourceFunc) utils_read_child_stderr, data, NULL);
  g_source_attach (data->child_stderr_source, data->main_context);
  g_source_unref (data->child_stderr_source);

 out:
  ;
}

void
polkit_backend_common_on_dir_monitor_changed (GFileMonitor     *monitor,
                                              GFile            *file,
                                              GFile            *other_file,
                                              GFileMonitorEvent event_type,
                                              gpointer          user_data)
{
  PolkitBackendJsAuthority *authority = POLKIT_BACKEND_JS_AUTHORITY (user_data);

  /* TODO: maybe rate-limit so storms of events are collapsed into one with a 500ms resolution?
   *       Because when editing a file with emacs we get 4-8 events..
   */

  if (file != NULL)
    {
      gchar *name;

      name = g_file_get_basename (file);

      /* g_print ("event_type=%d file=%p name=%s\n", event_type, file, name); */
      if (!g_str_has_prefix (name, ".") &&
          !g_str_has_prefix (name, "#") &&
          g_str_has_suffix (name, ".rules") &&
          (event_type == G_FILE_MONITOR_EVENT_CREATED ||
           event_type == G_FILE_MONITOR_EVENT_DELETED ||
           event_type == G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT))
        {
          polkit_backend_authority_log (POLKIT_BACKEND_AUTHORITY (authority),
                                        "Reloading rules");
          polkit_backend_common_reload_scripts (authority);
        }
      g_free (name);
    }
}

gboolean
polkit_backend_common_spawn_finish (GAsyncResult   *res,
                                    gint           *out_exit_status,
                                    gchar         **out_standard_output,
                                    gchar         **out_standard_error,
                                    GError        **error)
{
  GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
  UtilsSpawnData *data;
  gboolean ret = FALSE;

  g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
  g_return_val_if_fail (error == NULL || *error == NULL, FALSE);

  g_warn_if_fail (g_simple_async_result_get_source_tag (simple) == polkit_backend_common_spawn);

  if (g_simple_async_result_propagate_error (simple, error))
    goto out;

  data = (UtilsSpawnData*)g_simple_async_result_get_op_res_gpointer (simple);

  if (data->timed_out)
    {
      g_set_error (error,
                   G_IO_ERROR,
                   G_IO_ERROR_TIMED_OUT,
                   "Timed out after %d seconds",
                   data->timeout_seconds);
      goto out;
    }

  if (out_exit_status != NULL)
    *out_exit_status = data->exit_status;

  if (out_standard_output != NULL)
    *out_standard_output = g_strdup (data->child_stdout->str);

  if (out_standard_error != NULL)
    *out_standard_error = g_strdup (data->child_stderr->str);

  ret = TRUE;

 out:
  return ret;
}

static const gchar *
polkit_backend_js_authority_get_name (PolkitBackendAuthority *authority)
{
  return "js";
}

static const gchar *
polkit_backend_js_authority_get_version (PolkitBackendAuthority *authority)
{
  return PACKAGE_VERSION;
}

static PolkitAuthorityFeatures
polkit_backend_js_authority_get_features (PolkitBackendAuthority *authority)
{
  return POLKIT_AUTHORITY_FEATURES_TEMPORARY_AUTHORIZATION;
}

void
polkit_backend_common_js_authority_class_init_common (PolkitBackendJsAuthorityClass *klass)
{
  GObjectClass *gobject_class;
  PolkitBackendAuthorityClass *authority_class;
  PolkitBackendInteractiveAuthorityClass *interactive_authority_class;

  gobject_class = G_OBJECT_CLASS (klass);
  gobject_class->finalize                               = polkit_backend_common_js_authority_finalize;
  gobject_class->set_property                           = polkit_backend_common_js_authority_set_property;
  gobject_class->constructed                            = polkit_backend_common_js_authority_constructed;

  authority_class = POLKIT_BACKEND_AUTHORITY_CLASS (klass);
  authority_class->get_name                             = polkit_backend_js_authority_get_name;
  authority_class->get_version                          = polkit_backend_js_authority_get_version;
  authority_class->get_features                         = polkit_backend_js_authority_get_features;

  interactive_authority_class = POLKIT_BACKEND_INTERACTIVE_AUTHORITY_CLASS (klass);
  interactive_authority_class->get_admin_identities     = polkit_backend_common_js_authority_get_admin_auth_identities;
  interactive_authority_class->check_authorization_sync = polkit_backend_common_js_authority_check_authorization_sync;

  g_object_class_install_property (gobject_class,
                                   PROP_RULES_DIRS,
                                   g_param_spec_boxed ("rules-dirs",
                                                       NULL,
                                                       NULL,
                                                       G_TYPE_STRV,
                                                       G_PARAM_CONSTRUCT_ONLY | G_PARAM_WRITABLE));
}

gint
polkit_backend_common_rules_file_name_cmp (const gchar *a,
                                           const gchar *b)
{
  gint ret;
  const gchar *a_base;
  const gchar *b_base;

  a_base = strrchr (a, '/');
  b_base = strrchr (b, '/');

  g_assert (a_base != NULL);
  g_assert (b_base != NULL);
  a_base += 1;
  b_base += 1;

  ret = g_strcmp0 (a_base, b_base);
  if (ret == 0)
    {
      /* /etc wins over /usr */
      ret = g_strcmp0 (a, b);
      g_assert (ret != 0);
    }

  return ret;
}

const gchar *
polkit_backend_common_get_signal_name (gint signal_number)
{
  switch (signal_number)
    {
#define _HANDLE_SIG(sig) case sig: return #sig;
    _HANDLE_SIG (SIGHUP);
    _HANDLE_SIG (SIGINT);
    _HANDLE_SIG (SIGQUIT);
    _HANDLE_SIG (SIGILL);
    _HANDLE_SIG (SIGABRT);
    _HANDLE_SIG (SIGFPE);
    _HANDLE_SIG (SIGKILL);
    _HANDLE_SIG (SIGSEGV);
    _HANDLE_SIG (SIGPIPE);
    _HANDLE_SIG (SIGALRM);
    _HANDLE_SIG (SIGTERM);
    _HANDLE_SIG (SIGUSR1);
    _HANDLE_SIG (SIGUSR2);
    _HANDLE_SIG (SIGCHLD);
    _HANDLE_SIG (SIGCONT);
    _HANDLE_SIG (SIGSTOP);
    _HANDLE_SIG (SIGTSTP);
    _HANDLE_SIG (SIGTTIN);
    _HANDLE_SIG (SIGTTOU);
    _HANDLE_SIG (SIGBUS);
#ifdef SIGPOLL
    _HANDLE_SIG (SIGPOLL);
#endif
    _HANDLE_SIG (SIGPROF);
    _HANDLE_SIG (SIGSYS);
    _HANDLE_SIG (SIGTRAP);
    _HANDLE_SIG (SIGURG);
    _HANDLE_SIG (SIGVTALRM);
    _HANDLE_SIG (SIGXCPU);
    _HANDLE_SIG (SIGXFSZ);
#undef _HANDLE_SIG
    default:
      break;
    }
  return "UNKNOWN_SIGNAL";
}

void
polkit_backend_common_spawn_cb (GObject       *source_object,
                                GAsyncResult  *res,
                                gpointer       user_data)
{
  SpawnData *data = (SpawnData *)user_data;
  data->res = (GAsyncResult*)g_object_ref (res);
  g_main_loop_quit (data->loop);
}

void
polkit_backend_common_pidfd_to_systemd_unit (gint      pidfd,
                                             gchar   **ret_unit,
                                             gboolean *ret_no_new_privs)
{
  static int cached_has_pidfd_support = -1;
  GError *error = NULL;
  GDBusConnection *connection = NULL;
  GMainContext *tmp_context = NULL;
  GVariant *result = NULL, *no_new_privs_result = NULL, *no_new_privis_value;
  GUnixFDList *fd_list = NULL;
  const char *unit_path, *unit;
  int fd_id;

  /* Try to lookup using a PIDFD, so that we do not have issues with PIDs being
   * recycled under our nose. For that we need both a kernel that supports the
   * PIDFD syscalls (no wrapper from glibc, so need to call it directly) and a
   * version of systemd with the new GetUnitByPIDFD method. If either are not
   * available, then return nothing, as we don't want to be open to PID recycle
   * attacks.
   */

  g_assert (ret_unit != NULL);
  g_assert (ret_no_new_privs != NULL);

  if (pidfd < 0 || cached_has_pidfd_support == 0)
    return;

  connection = g_bus_get_sync (G_BUS_TYPE_SYSTEM, NULL, &error);
  if (connection == NULL)
    {
      g_warning ("Error getting system bus: %s", error->message);
      goto out;
    }

  tmp_context = g_main_context_new ();
  g_main_context_push_thread_default (tmp_context);

  fd_list = g_unix_fd_list_new ();
  if (fd_list == NULL)
    goto out;

  fd_id = g_unix_fd_list_append (fd_list, pidfd, &error);
  if (fd_id < 0)
    {
      g_warning ("Error appending PID FD to fd list: %s", error->message);
      goto out;
    }

  result = g_dbus_connection_call_with_unix_fd_list_sync (connection,
        "org.freedesktop.systemd1",         /* name */
        "/org/freedesktop/systemd1",        /* object path */
        "org.freedesktop.systemd1.Manager", /* interface name */
        "GetUnitByPIDFD",                   /* method */
        g_variant_new ("(h)", fd_id),
        G_VARIANT_TYPE ("(osay)"),
        G_DBUS_CALL_FLAGS_NONE,
        -1,
        fd_list,
        NULL,
        NULL,
        &error);

  if (result == NULL)
    {
      if (g_error_matches (error, G_DBUS_ERROR, G_DBUS_ERROR_UNKNOWN_METHOD))
        cached_has_pidfd_support = 0;

      g_warning ("Error calling GetUnitByPIDFD: %s", error->message);
      goto out;
    }

  g_variant_get (result, "(&o&say)", &unit_path, &unit, NULL);
  if (unit == NULL)
    goto out;

  /* Check for NoNewPrivileges property being set on the unit via D-Bus, and
   * return if it is not. This protects against PID changes, as if unset the
   * unit could use a setuid binary. */
  no_new_privs_result = g_dbus_connection_call_sync (connection,
        "org.freedesktop.systemd1",         /* name */
        unit_path,                          /* object path */
        "org.freedesktop.DBus.Properties",  /* interface name */
        "Get",                              /* method */
        g_variant_new ("(ss)", "org.freedesktop.systemd1.Service", "NoNewPrivileges"),
        G_VARIANT_TYPE ("(v)"),
        G_DBUS_CALL_FLAGS_NONE,
        -1,
        NULL,
        &error);

  if (no_new_privs_result == NULL)
    {
      g_warning ("Error calling Get on NoNewPrivileges property for unit %s: %s", unit, error->message);
      goto out;
    }

  g_variant_get (no_new_privs_result, "(v)", &no_new_privis_value);
  if (no_new_privis_value == NULL)
    {
      g_warning ("Error getting value for NoNewPrivileges property for unit %s", unit);
      goto out;
    }

  *ret_unit = strdup (unit);
  if (!*ret_unit)
    {
      g_warning ("Failed to allocate memory for systemd unit ID");
      goto out;
    }

  *ret_no_new_privs = g_variant_get_boolean (no_new_privis_value);

 out:
  if (tmp_context)
    {
      g_main_context_pop_thread_default (tmp_context);
      g_main_context_unref (tmp_context);
    }
  if (connection != NULL)
    g_object_unref (connection);
  if (result != NULL)
    g_variant_unref (result);
  if (no_new_privs_result != NULL)
    g_variant_unref (no_new_privs_result);
  if (fd_list != NULL)
    g_object_unref (fd_list);
  if (error)
    g_error_free (error);
}
