/* GDBus - GLib D-Bus Library

 *

 * Copyright (C) 2008-2010 Red Hat, Inc.

 *

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * 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 2.1 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/>.

 *

 * Author: David Zeuthen <davidz@redhat.com>

 */

#include "config.h"

#include <stdlib.h>

#include <string.h>

#include "gdbusauthobserver.h"

#include "gdbusconnection.h"

#include "gdbusdaemon.h"

#include "gdbuserror.h"

#include "gdbusintrospection.h"

#include "gdbusmessage.h"

#include "gdbusprivate.h"

#include "gdbusproxy.h"

#include "ginputstream.h"

#include "gioenumtypes.h"

#include "giomodule-priv.h"

#include "giostream.h"

#include "giotypes.h"

#include "glib-private.h"

#include "glib/gstdio.h"

#include "gmemoryinputstream.h"

#include "gsocket.h"

#include "gsocketaddress.h"

#include "gsocketconnection.h"

#include "gsocketcontrolmessage.h"

#include "gsocketoutputstream.h"

#include "gtask.h"

#ifdef G_OS_UNIX

#include "gunixfdmessage.h"

#include "gunixconnection.h"

#include "gunixcredentialsmessage.h"

#endif

#ifdef G_OS_WIN32

#include <windows.h>

#include <io.h>

#include <conio.h>

#include "gwin32sid.h"

#endif

#include "glibintl.h"

static gboolean _g_dbus_worker_do_initial_read (gpointer data);

static void schedule_pending_close (GDBusWorker *worker);

/* ---------------------------------------------------------------------------------------------------- */

gchar *

_g_dbus_hexdump (const gchar *data, gsize len, guint indent)

{

 guint n, m;

 GString *ret;

 ret = g_string_new (NULL);

 for (n = 0; n < len; n += 16)

   {

     g_string_append_printf (ret, "%*s%04x: ", indent, "", n);

     for (m = n; m < n + 16; m++)

       {

         if (m > n && (m%4) == 0)

           g_string_append_c (ret, ' ');

         if (m < len)

           g_string_append_printf (ret, "%02x ", (guchar) data[m]);

         else

           g_string_append (ret, "   ");

       }

     g_string_append (ret, "   ");

     for (m = n; m < len && m < n + 16; m++)

       g_string_append_c (ret, g_ascii_isprint (data[m]) ? data[m] : '.');

     g_string_append_c (ret, '\n');

   }

 return g_string_free (ret, FALSE);

}

/* ---------------------------------------------------------------------------------------------------- */

/* Unfortunately ancillary messages are discarded when reading from a

 * socket using the GSocketInputStream abstraction. So we provide a

 * very GInputStream-ish API that uses GSocket in this case (very

 * similar to GSocketInputStream).

 */

typedef struct

{

  void *buffer;

  gsize count;

  GSocketControlMessage ***messages;

  gint *num_messages;

} ReadWithControlData;

static void

read_with_control_data_free (ReadWithControlData *data)

{

  g_slice_free (ReadWithControlData, data);

}

static gboolean

_g_socket_read_with_control_messages_ready (GSocket      *socket,

                                            GIOCondition  condition,

                                            gpointer      user_data)

{

  GTask *task = user_data;

  ReadWithControlData *data = g_task_get_task_data (task);

  GError *error;

  gssize result;

  GInputVector vector;

  error = NULL;

  vector.buffer = data->buffer;

  vector.size = data->count;

  result = g_socket_receive_message (socket,

                                     NULL, /* address */

                                     &vector,

                                     1,

                                     data->messages,

                                     data->num_messages,

                                     NULL,

                                     g_task_get_cancellable (task),

                                     &error);

  if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_WOULD_BLOCK))

    {

      g_error_free (error);

      return TRUE;

    }

  g_assert (result >= 0 || error != NULL);

  if (result >= 0)

    g_task_return_int (task, result);

  else

    g_task_return_error (task, error);

  g_object_unref (task);

  return FALSE;

}

static void

_g_socket_read_with_control_messages (GSocket                 *socket,

                                      void                    *buffer,

                                      gsize                    count,

                                      GSocketControlMessage ***messages,

                                      gint                    *num_messages,

                                      gint                     io_priority,

                                      GCancellable            *cancellable,

                                      GAsyncReadyCallback      callback,

                                      gpointer                 user_data)

{

  GTask *task;

  ReadWithControlData *data;

  GSource *source;

  data = g_slice_new0 (ReadWithControlData);

  data->buffer = buffer;

  data->count = count;

  data->messages = messages;

  data->num_messages = num_messages;

  task = g_task_new (socket, cancellable, callback, user_data);

  g_task_set_source_tag (task, _g_socket_read_with_control_messages);

  g_task_set_name (task, "[gio] D-Bus read");

  g_task_set_task_data (task, data, (GDestroyNotify) read_with_control_data_free);

  if (g_socket_condition_check (socket, G_IO_IN))

    {

      if (!_g_socket_read_with_control_messages_ready (socket, G_IO_IN, task))

        return;

    }

  source = g_socket_create_source (socket,

                                   G_IO_IN | G_IO_HUP | G_IO_ERR,

                                   cancellable);

  g_task_attach_source (task, source, (GSourceFunc) _g_socket_read_with_control_messages_ready);

  g_source_unref (source);

}

static gssize

_g_socket_read_with_control_messages_finish (GSocket       *socket,

                                             GAsyncResult  *result,

                                             GError       **error)

{

  g_return_val_if_fail (G_IS_SOCKET (socket), -1);

  g_return_val_if_fail (g_task_is_valid (result, socket), -1);

  return g_task_propagate_int (G_TASK (result), error);

}

/* ---------------------------------------------------------------------------------------------------- */

/* Work-around for https://bugzilla.gnome.org/show_bug.cgi?id=674885

   and see also the original https://bugzilla.gnome.org/show_bug.cgi?id=627724  */

static GPtrArray *ensured_classes = NULL;

static void

ensure_type (GType gtype)

{

  g_ptr_array_add (ensured_classes, g_type_class_ref (gtype));

}

static void

release_required_types (void)

{

  g_ptr_array_foreach (ensured_classes, (GFunc) g_type_class_unref, NULL);

  g_ptr_array_unref (ensured_classes);

  ensured_classes = NULL;

}

static void

ensure_required_types (void)

{

  g_assert (ensured_classes == NULL);

  ensured_classes = g_ptr_array_new ();

  /* Generally in this list, you should initialize types which are used as

   * properties first, then the class which has them. For example, GDBusProxy

   * has a type of GDBusConnection, so we initialize GDBusConnection first.

   * And because GDBusConnection has a property of type GDBusConnectionFlags,

   * we initialize that first.

   *

   * Similarly, GSocket has a type of GSocketAddress.

   *

   * We don't fill out the whole dependency tree right now because in practice

   * it tends to be just types that GDBus use that cause pain, and there

   * is work on a more general approach in https://bugzilla.gnome.org/show_bug.cgi?id=674885

   */

  ensure_type (G_TYPE_TASK);

  ensure_type (G_TYPE_MEMORY_INPUT_STREAM);

  ensure_type (G_TYPE_DBUS_CONNECTION_FLAGS);

  ensure_type (G_TYPE_DBUS_CAPABILITY_FLAGS);

  ensure_type (G_TYPE_DBUS_AUTH_OBSERVER);

  ensure_type (G_TYPE_DBUS_CONNECTION);

  ensure_type (G_TYPE_DBUS_PROXY);

  ensure_type (G_TYPE_SOCKET_FAMILY);

  ensure_type (G_TYPE_SOCKET_TYPE);

  ensure_type (G_TYPE_SOCKET_PROTOCOL);

  ensure_type (G_TYPE_SOCKET_ADDRESS);

  ensure_type (G_TYPE_SOCKET);

}

/* ---------------------------------------------------------------------------------------------------- */

typedef struct

{

  gint refcount;  /* (atomic) */

  GThread *thread;

  GMainContext *context;

  GMainLoop *loop;

} SharedThreadData;

static gpointer

gdbus_shared_thread_func (gpointer user_data)

{

  SharedThreadData *data = user_data;

  g_main_context_push_thread_default (data->context);

  g_main_loop_run (data->loop);

  g_main_context_pop_thread_default (data->context);

  release_required_types ();

  return NULL;

}

/* ---------------------------------------------------------------------------------------------------- */

static SharedThreadData *

_g_dbus_shared_thread_ref (void)

{

  static SharedThreadData *shared_thread_data = 0;

  if (g_once_init_enter_pointer (&shared_thread_data))

    {

      SharedThreadData *data;

      data = g_new0 (SharedThreadData, 1);

      data->refcount = 0;

      data->context = g_main_context_new ();

      data->loop = g_main_loop_new (data->context, FALSE);

      data->thread = g_thread_new ("gdbus",

                                   gdbus_shared_thread_func,

                                   data);

      /* We can cast between gsize and gpointer safely */

      g_once_init_leave_pointer (&shared_thread_data, data);

    }

  g_atomic_int_inc (&shared_thread_data->refcount);

  return shared_thread_data;

}

static void

_g_dbus_shared_thread_unref (SharedThreadData *data)

{

  /* TODO: actually destroy the shared thread here */

#if 0

  g_assert (data != NULL);

  if (g_atomic_int_dec_and_test (&data->refcount))

    {

      g_main_loop_quit (data->loop);

      //g_thread_join (data->thread);

      g_main_loop_unref (data->loop);

      g_main_context_unref (data->context);

    }

#endif

}

/* ---------------------------------------------------------------------------------------------------- */

typedef enum {

    PENDING_NONE = 0,

    PENDING_WRITE,

    PENDING_FLUSH,

    PENDING_CLOSE

} OutputPending;

struct GDBusWorker

{

  gint                                ref_count;  /* (atomic) */

  SharedThreadData                   *shared_thread_data;

  /* really a boolean, but GLib 2.28 lacks atomic boolean ops */

  gint                                stopped;  /* (atomic) */

  /* TODO: frozen (e.g. G_DBUS_CONNECTION_FLAGS_DELAY_MESSAGE_PROCESSING) currently

   * only affects messages received from the other peer (since GDBusServer is the

   * only user) - we might want it to affect messages sent to the other peer too?

   */

  gboolean                            frozen;

  GDBusCapabilityFlags                capabilities;

  GQueue                             *received_messages_while_frozen;

  GIOStream                          *stream;

  GCancellable                       *cancellable;

  GDBusWorkerMessageReceivedCallback  message_received_callback;

  GDBusWorkerMessageAboutToBeSentCallback message_about_to_be_sent_callback;

  GDBusWorkerDisconnectedCallback     disconnected_callback;

  gpointer                            user_data;

  /* if not NULL, stream is GSocketConnection */

  GSocket *socket;

  /* used for reading */

  GMutex                              read_lock;

  gchar                              *read_buffer;

  gsize                               read_buffer_allocated_size;

  gsize                               read_buffer_cur_size;

  gsize                               read_buffer_bytes_wanted;

  GUnixFDList                        *read_fd_list;

  GSocketControlMessage             **read_ancillary_messages;

  gint                                read_num_ancillary_messages;

  /* Whether an async write, flush or close, or none of those, is pending.

   * Only the worker thread may change its value, and only with the write_lock.

   * Other threads may read its value when holding the write_lock.

   * The worker thread may read its value at any time.

   */

  OutputPending                       output_pending;

  /* used for writing */

  GMutex                              write_lock;

  /* queue of MessageToWriteData, protected by write_lock */

  GQueue                             *write_queue;

  /* protected by write_lock */

  guint64                             write_num_messages_written;

  /* number of messages we'd written out last time we flushed;

   * protected by write_lock

   */

  guint64                             write_num_messages_flushed;

  /* list of FlushData, protected by write_lock */

  GList                              *write_pending_flushes;

  /* list of CloseData, protected by write_lock */

  GList                              *pending_close_attempts;

  /* no lock - only used from the worker thread */

  gboolean                            close_expected;

};

static void _g_dbus_worker_unref (GDBusWorker *worker);

/* ---------------------------------------------------------------------------------------------------- */

typedef struct

{

  GMutex  mutex;

  GCond   cond;

  guint64 number_to_wait_for;

  gboolean finished;

  GError *error;

} FlushData;

struct _MessageToWriteData ;

typedef struct _MessageToWriteData MessageToWriteData;

static void message_to_write_data_free (MessageToWriteData *data);

static void read_message_print_transport_debug (gssize bytes_read,

                                                GDBusWorker *worker);

static void write_message_print_transport_debug (gssize bytes_written,

                                                 MessageToWriteData *data);

typedef struct {

    GDBusWorker *worker;

    GTask *task;

} CloseData;

static void close_data_free (CloseData *close_data)

{

  g_clear_object (&close_data->task);

  _g_dbus_worker_unref (close_data->worker);

  g_slice_free (CloseData, close_data);

}

/* ---------------------------------------------------------------------------------------------------- */

static GDBusWorker *

_g_dbus_worker_ref (GDBusWorker *worker)

{

  g_atomic_int_inc (&worker->ref_count);

  return worker;

}

static void

_g_dbus_worker_unref (GDBusWorker *worker)

{

  if (g_atomic_int_dec_and_test (&worker->ref_count))

    {

      g_assert (worker->write_pending_flushes == NULL);

      _g_dbus_shared_thread_unref (worker->shared_thread_data);

      g_object_unref (worker->stream);

      g_mutex_clear (&worker->read_lock);

      g_object_unref (worker->cancellable);

      if (worker->read_fd_list != NULL)

        g_object_unref (worker->read_fd_list);

      g_queue_free_full (worker->received_messages_while_frozen, (GDestroyNotify) g_object_unref);

      g_mutex_clear (&worker->write_lock);

      g_queue_free_full (worker->write_queue, (GDestroyNotify) message_to_write_data_free);

      g_free (worker->read_buffer);

      g_free (worker);

    }

}

static void

_g_dbus_worker_emit_disconnected (GDBusWorker  *worker,

                                  gboolean      remote_peer_vanished,

                                  GError       *error)

{

  if (!g_atomic_int_get (&worker->stopped))

    worker->disconnected_callback (worker, remote_peer_vanished, error, worker->user_data);

}

static void

_g_dbus_worker_emit_message_received (GDBusWorker  *worker,

                                      GDBusMessage *message)

{

  if (!g_atomic_int_get (&worker->stopped))

    worker->message_received_callback (worker, message, worker->user_data);

}

static GDBusMessage *

_g_dbus_worker_emit_message_about_to_be_sent (GDBusWorker  *worker,

                                              GDBusMessage *message)

{

  GDBusMessage *ret;

  if (!g_atomic_int_get (&worker->stopped))

    ret = worker->message_about_to_be_sent_callback (worker, g_steal_pointer (&message), worker->user_data);

  else

    ret = g_steal_pointer (&message);

  return ret;

}

/* can only be called from private thread with read-lock held - takes ownership of @message */

static void

_g_dbus_worker_queue_or_deliver_received_message (GDBusWorker  *worker,

                                                  GDBusMessage *message)

{

  if (worker->frozen || g_queue_get_length (worker->received_messages_while_frozen) > 0)

    {

      /* queue up */

      g_queue_push_tail (worker->received_messages_while_frozen, g_steal_pointer (&message));

    }

  else

    {

      /* not frozen, nor anything in queue */

      _g_dbus_worker_emit_message_received (worker, message);

      g_clear_object (&message);

    }

}

/* called in private thread shared by all GDBusConnection instances (without read-lock held) */

static gboolean

unfreeze_in_idle_cb (gpointer user_data)

{

  GDBusWorker *worker = user_data;

  GDBusMessage *message;

  g_mutex_lock (&worker->read_lock);

  if (worker->frozen)

    {

      while ((message = g_queue_pop_head (worker->received_messages_while_frozen)) != NULL)

        {

          _g_dbus_worker_emit_message_received (worker, message);

          g_clear_object (&message);

        }

      worker->frozen = FALSE;

    }

  else

    {

      g_assert (g_queue_get_length (worker->received_messages_while_frozen) == 0);

    }

  g_mutex_unlock (&worker->read_lock);

  return FALSE;

}

/* can be called from any thread */

void

_g_dbus_worker_unfreeze (GDBusWorker *worker)

{

  GSource *idle_source;

  idle_source = g_idle_source_new ();

  g_source_set_priority (idle_source, G_PRIORITY_DEFAULT);

  g_source_set_callback (idle_source,

                         unfreeze_in_idle_cb,

                         _g_dbus_worker_ref (worker),

                         (GDestroyNotify) _g_dbus_worker_unref);

  g_source_set_static_name (idle_source, "[gio] unfreeze_in_idle_cb");

  g_source_attach (idle_source, worker->shared_thread_data->context);

  g_source_unref (idle_source);

}

/* ---------------------------------------------------------------------------------------------------- */

static void _g_dbus_worker_do_read_unlocked (GDBusWorker *worker);

/* called in private thread shared by all GDBusConnection instances (without read-lock held) */

static void

_g_dbus_worker_do_read_cb (GInputStream  *input_stream,

                           GAsyncResult  *res,

                           gpointer       user_data)

{

  GDBusWorker *worker = user_data;

  GError *error;

  gssize bytes_read;

  g_mutex_lock (&worker->read_lock);

  /* If already stopped, don't even process the reply */

  if (g_atomic_int_get (&worker->stopped))

    goto out;

  error = NULL;

  if (worker->socket == NULL)

    bytes_read = g_input_stream_read_finish (g_io_stream_get_input_stream (worker->stream),

                                             res,

                                             &error);

  else

    bytes_read = _g_socket_read_with_control_messages_finish (worker->socket,

                                                              res,

                                                              &error);

  if (worker->read_num_ancillary_messages > 0)

    {

      gint n;

      for (n = 0; n < worker->read_num_ancillary_messages; n++)

        {

          GSocketControlMessage *control_message = G_SOCKET_CONTROL_MESSAGE (worker->read_ancillary_messages[n]);

          if (FALSE)

            {

            }

#ifdef G_OS_UNIX

          else if (G_IS_UNIX_FD_MESSAGE (control_message))

            {

              GUnixFDMessage *fd_message;

              gint *fds;

              gint num_fds;

              fd_message = G_UNIX_FD_MESSAGE (control_message);

              fds = g_unix_fd_message_steal_fds (fd_message, &num_fds);

              if (worker->read_fd_list == NULL)

                {

                  worker->read_fd_list = g_unix_fd_list_new_from_array (fds, num_fds);

                }

              else

                {

                  gint n;

                  for (n = 0; n < num_fds; n++)

                    {

                      /* TODO: really want a append_steal() */

                      g_unix_fd_list_append (worker->read_fd_list, fds[n], NULL);

                      (void) g_close (fds[n], NULL);

                    }

                }

              g_free (fds);

            }

          else if (G_IS_UNIX_CREDENTIALS_MESSAGE (control_message))

            {

              /* do nothing */

            }

#endif

          else

            {

              if (error == NULL)

                {

                  g_set_error (&error,

                               G_IO_ERROR,

                               G_IO_ERROR_FAILED,

                               "Unexpected ancillary message of type %s received from peer",

                               g_type_name (G_TYPE_FROM_INSTANCE (control_message)));

                  _g_dbus_worker_emit_disconnected (worker, TRUE, error);

                  g_error_free (error);

                  g_object_unref (control_message);

                  n++;

                  while (n < worker->read_num_ancillary_messages)

                    g_object_unref (worker->read_ancillary_messages[n++]);

                  g_free (worker->read_ancillary_messages);

                  goto out;

                }

            }

          g_object_unref (control_message);

        }

      g_free (worker->read_ancillary_messages);

    }

  if (bytes_read == -1)

    {

      if (G_UNLIKELY (_g_dbus_debug_transport ()))

        {

          _g_dbus_debug_print_lock ();

          g_print ("========================================================================\n"

                   "GDBus-debug:Transport:\n"

                   "  ---- READ ERROR on stream of type %s:\n"

                   "  ---- %s %d: %s\n",

                   g_type_name (G_TYPE_FROM_INSTANCE (g_io_stream_get_input_stream (worker->stream))),

                   g_quark_to_string (error->domain), error->code,

                   error->message);

          _g_dbus_debug_print_unlock ();

        }

      /* Every async read that uses this callback uses worker->cancellable

       * as its GCancellable. worker->cancellable gets cancelled if and only

       * if the GDBusConnection tells us to close (either via

       * _g_dbus_worker_stop, which is called on last-unref, or directly),

       * so a cancelled read must mean our connection was closed locally.

       *

       * If we're closing, other errors are possible - notably,

       * G_IO_ERROR_CLOSED can be seen if we close the stream with an async

       * read in-flight. It seems sensible to treat all read errors during

       * closing as an expected thing that doesn't trip exit-on-close.

       *

       * Because close_expected can't be set until we get into the worker

       * thread, but the cancellable is signalled sooner (from another

       * thread), we do still need to check the error.

       */

      if (worker->close_expected ||

          g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))

        _g_dbus_worker_emit_disconnected (worker, FALSE, NULL);

      else

        _g_dbus_worker_emit_disconnected (worker, TRUE, error);

      g_error_free (error);

      goto out;

    }

#if 0

  g_debug ("read %d bytes (is_closed=%d blocking=%d condition=0x%02x) stream %p, %p",

           (gint) bytes_read,

           g_socket_is_closed (g_socket_connection_get_socket (G_SOCKET_CONNECTION (worker->stream))),

           g_socket_get_blocking (g_socket_connection_get_socket (G_SOCKET_CONNECTION (worker->stream))),

           g_socket_condition_check (g_socket_connection_get_socket (G_SOCKET_CONNECTION (worker->stream)),

                                     G_IO_IN | G_IO_OUT | G_IO_HUP),

           worker->stream,

           worker);

#endif

  /* The read failed, which could mean the dbus-daemon was sent SIGTERM. */

  if (bytes_read == 0)

    {

      g_set_error (&error,

                   G_IO_ERROR,

                   G_IO_ERROR_FAILED,

                   "Underlying GIOStream returned 0 bytes on an async read");

      _g_dbus_worker_emit_disconnected (worker, TRUE, error);

      g_error_free (error);

      goto out;

    }

  read_message_print_transport_debug (bytes_read, worker);

  worker->read_buffer_cur_size += bytes_read;

  if (worker->read_buffer_bytes_wanted == worker->read_buffer_cur_size)

    {

      /* OK, got what we asked for! */

      if (worker->read_buffer_bytes_wanted == 16)

        {

          gssize message_len;

          /* OK, got the header - determine how many more bytes are needed */

          error = NULL;

          message_len = g_dbus_message_bytes_needed ((guchar *) worker->read_buffer,

                                                     16,

                                                     &error);

          if (message_len == -1)

            {

              g_warning ("_g_dbus_worker_do_read_cb: error determining bytes needed: %s", error->message);

              _g_dbus_worker_emit_disconnected (worker, FALSE, error);

              g_error_free (error);

              goto out;

            }

          worker->read_buffer_bytes_wanted = message_len;

          _g_dbus_worker_do_read_unlocked (worker);

        }

      else

        {

          GDBusMessage *message;

          error = NULL;

          /* TODO: use connection->priv->auth to decode the message */

          message = g_dbus_message_new_from_blob ((guchar *) worker->read_buffer,

                                                  worker->read_buffer_cur_size,

                                                  worker->capabilities,

                                                  &error);

          if (message == NULL)

            {

              gchar *s;

              s = _g_dbus_hexdump (worker->read_buffer, worker->read_buffer_cur_size, 2);

              g_warning ("Error decoding D-Bus message of %" G_GSIZE_FORMAT " bytes\n"

                         "The error is: %s\n"

                         "The payload is as follows:\n"

                         "%s",

                         worker->read_buffer_cur_size,

                         error->message,

                         s);

              g_free (s);

              _g_dbus_worker_emit_disconnected (worker, FALSE, error);

              g_error_free (error);

              goto out;

            }

#ifdef G_OS_UNIX

          if (worker->read_fd_list != NULL)

            {

              g_dbus_message_set_unix_fd_list (message, worker->read_fd_list);

              g_object_unref (worker->read_fd_list);

              worker->read_fd_list = NULL;

            }

#endif

          if (G_UNLIKELY (_g_dbus_debug_message ()))

            {

              gchar *s;

              _g_dbus_debug_print_lock ();

              g_print ("========================================================================\n"

                       "GDBus-debug:Message:\n"

                       "  <<<< RECEIVED D-Bus message (%" G_GSIZE_FORMAT " bytes)\n",

                       worker->read_buffer_cur_size);

              s = g_dbus_message_print (message, 2);

              g_print ("%s", s);

              g_free (s);

              if (G_UNLIKELY (_g_dbus_debug_payload ()))

                {

                  s = _g_dbus_hexdump (worker->read_buffer, worker->read_buffer_cur_size, 2);

                  g_print ("%s\n", s);

                  g_free (s);

                }

              _g_dbus_debug_print_unlock ();

            }

          /* yay, got a message, go deliver it */

          _g_dbus_worker_queue_or_deliver_received_message (worker, g_steal_pointer (&message));

          /* start reading another message! */

          worker->read_buffer_bytes_wanted = 0;

          worker->read_buffer_cur_size = 0;

          _g_dbus_worker_do_read_unlocked (worker);

        }

    }

  else

    {

      /* didn't get all the bytes we requested - so repeat the request... */

      _g_dbus_worker_do_read_unlocked (worker);

    }

 out:

  g_mutex_unlock (&worker->read_lock);

  /* check if there is any pending close */

  schedule_pending_close (worker);

  /* gives up the reference acquired when calling g_input_stream_read_async() */

  _g_dbus_worker_unref (worker);

}

/* called in private thread shared by all GDBusConnection instances (with read-lock held) */

static void

_g_dbus_worker_do_read_unlocked (GDBusWorker *worker)

{

  /* Note that we do need to keep trying to read even if close_expected is

   * true, because only failing a read causes us to signal 'closed'.

   */

  /* if bytes_wanted is zero, it means start reading a message */

  if (worker->read_buffer_bytes_wanted == 0)

    {

      worker->read_buffer_cur_size = 0;

      worker->read_buffer_bytes_wanted = 16;

    }

  /* ensure we have a (big enough) buffer */

  if (worker->read_buffer == NULL || worker->read_buffer_bytes_wanted > worker->read_buffer_allocated_size)

    {

      /* TODO: 4096 is randomly chosen; might want a better chosen default minimum */

      worker->read_buffer_allocated_size = MAX (worker->read_buffer_bytes_wanted, 4096);

      worker->read_buffer = g_realloc (worker->read_buffer, worker->read_buffer_allocated_size);

    }

  if (worker->socket == NULL)

    g_input_stream_read_async (g_io_stream_get_input_stream (worker->stream),

                               worker->read_buffer + worker->read_buffer_cur_size,

                               worker->read_buffer_bytes_wanted - worker->read_buffer_cur_size,

                               G_PRIORITY_DEFAULT,

                               worker->cancellable,

                               (GAsyncReadyCallback) _g_dbus_worker_do_read_cb,

                               _g_dbus_worker_ref (worker));

  else

    {

      worker->read_ancillary_messages = NULL;

      worker->read_num_ancillary_messages = 0;

      _g_socket_read_with_control_messages (worker->socket,

                                            worker->read_buffer + worker->read_buffer_cur_size,

                                            worker->read_buffer_bytes_wanted - worker->read_buffer_cur_size,

                                            &worker->read_ancillary_messages,

                                            &worker->read_num_ancillary_messages,

                                            G_PRIORITY_DEFAULT,

                                            worker->cancellable,

                                            (GAsyncReadyCallback) _g_dbus_worker_do_read_cb,

                                            _g_dbus_worker_ref (worker));

    }

}

/* called in private thread shared by all GDBusConnection instances (without read-lock held) */

static gboolean

_g_dbus_worker_do_initial_read (gpointer data)

{

  GDBusWorker *worker = data;

  g_mutex_lock (&worker->read_lock);

  _g_dbus_worker_do_read_unlocked (worker);

  g_mutex_unlock (&worker->read_lock);

  return FALSE;

}

/* ---------------------------------------------------------------------------------------------------- */

struct _MessageToWriteData

{

  GDBusWorker  *worker;

  GDBusMessage *message;  /* (owned) */

  gchar        *blob;

  gsize         blob_size;

  gsize         total_written;

  GTask        *task;  /* (owned) and (nullable) before writing starts and after g_task_return_*() is called */

};

static void

message_to_write_data_free (MessageToWriteData *data)

{

  _g_dbus_worker_unref (data->worker);

  g_clear_object (&data->message);

  g_free (data->blob);

  /* The task must either not have been created, or have been created, returned

   * and finalised by now. */

  g_assert (data->task == NULL);

  g_slice_free (MessageToWriteData, data);

}

/* ---------------------------------------------------------------------------------------------------- */

static void write_message_continue_writing (MessageToWriteData *data);

/* called in private thread shared by all GDBusConnection instances

 *

 * write-lock is not held on entry

 * output_pending is PENDING_WRITE on entry

 * @user_data is (transfer full)

 */

static void

write_message_async_cb (GObject      *source_object,

                        GAsyncResult *res,

                        gpointer      user_data)

{

  MessageToWriteData *data = g_steal_pointer (&user_data);

  gssize bytes_written;

  GError *error;

  /* The ownership of @data is a bit odd in this function: it’s (transfer full)

   * when the function is called, but the code paths which call g_task_return_*()

   * on @data->task will indirectly cause it to be freed, because @data is

   * always guaranteed to be the user_data in the #GTask. So that’s why it looks

   * like @data is not always freed on every code path in this function. */

  error = NULL;

  bytes_written = g_output_stream_write_finish (G_OUTPUT_STREAM (source_object),

                                                res,

                                                &error);

  if (bytes_written == -1)

    {

      GTask *task = g_steal_pointer (&data->task);

      g_task_return_error (task, error);

      g_clear_object (&task);

      goto out;

    }

  g_assert (bytes_written > 0); /* zero is never returned */