gio/gunixconnection.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright © 2009 Codethink Limited
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License as published
   7  * by the Free Software Foundation; either version 2 of the licence or (at
   8  * your option) any later version.
   9  *
  10  * See the included COPYING file for more information.
  11  *
  12  * Authors: Ryan Lortie <desrt@desrt.ca>
  13  */
  14
  15 #include "config.h"
  16 #include "gunixconnection.h"
  17 #include "gunixcredentialsmessage.h"
  18 #include "glibintl.h"
  19
  20 /**
  21  * SECTION:gunixconnection
  22  * @title: GUnixConnection
  23  * @short_description: A UNIX domain GSocketConnection
  24  * @include: gio/gunixconnection.h
  25  * @see_also: #GSocketConnection.
  26  *
  27  * This is the subclass of #GSocketConnection that is created
  28  * for UNIX domain sockets.
  29  *
  30  * It contains functions to do some of the UNIX socket specific
  31  * functionality like passing file descriptors.
  32  *
  33  * Note that <filename>&lt;gio/gunixconnection.h&gt;</filename> belongs to
  34  * the UNIX-specific GIO interfaces, thus you have to use the
  35  * <filename>gio-unix-2.0.pc</filename> pkg-config file when using it.
  36  *
  37  * Since: 2.22
  38  */
  39
  40 #include <gio/gsocketcontrolmessage.h>
  41 #include <gio/gunixfdmessage.h>
  42 #include <gio/gsocket.h>
  43 #include <unistd.h>
  44
  45 #ifdef __linux__
  46 /* for getsockopt() and setsockopt() */
  47 #include <sys/types.h>          /* See NOTES */
  48 #include <sys/socket.h>
  49 #include <errno.h>
  50 #include <string.h>
  51 #endif
  52
  53
  54 G_DEFINE_TYPE_WITH_CODE (GUnixConnection, g_unix_connection,
  55                          G_TYPE_SOCKET_CONNECTION,
  56   g_socket_connection_factory_register_type (g_define_type_id,
  57                                              G_SOCKET_FAMILY_UNIX,
  58                                              G_SOCKET_TYPE_STREAM,
  59                                              G_SOCKET_PROTOCOL_DEFAULT);
  60                          );
  61
  62 /**
  63  * g_unix_connection_send_fd:
  64  * @connection: a #GUnixConnection
  65  * @fd: a file descriptor
  66  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
  67  * @error: (allow-none): #GError for error reporting, or %NULL to ignore.
  68  *
  69  * Passes a file descriptor to the receiving side of the
  70  * connection. The receiving end has to call g_unix_connection_receive_fd()
  71  * to accept the file descriptor.
  72  *
  73  * As well as sending the fd this also writes a single byte to the
  74  * stream, as this is required for fd passing to work on some
  75  * implementations.
  76  *
  77  * Returns: a %TRUE on success, %NULL on error.
  78  *
  79  * Since: 2.22
  80  */
  81 gboolean
  82 g_unix_connection_send_fd (GUnixConnection  *connection,
  83                            gint              fd,
  84                            GCancellable     *cancellable,
  85                            GError          **error)
  86 {
  87   GSocketControlMessage *scm;
  88   GSocket *socket;
  89
  90   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), FALSE);
  91   g_return_val_if_fail (fd >= 0, FALSE);
  92
  93   scm = g_unix_fd_message_new ();
  94
  95   if (!g_unix_fd_message_append_fd (G_UNIX_FD_MESSAGE (scm), fd, error))
  96     {
  97       g_object_unref (scm);
  98       return FALSE;
  99     }
 100
 101   g_object_get (connection, "socket", &socket, NULL);
 102   if (g_socket_send_message (socket, NULL, NULL, 0, &scm, 1, 0, cancellable, error) != 1)
 103     /* XXX could it 'fail' with zero? */
 104     {
 105       g_object_unref (socket);
 106       g_object_unref (scm);
 107
 108       return FALSE;
 109     }
 110
 111   g_object_unref (socket);
 112   g_object_unref (scm);
 113
 114   return TRUE;
 115 }
 116
 117 /**
 118  * g_unix_connection_receive_fd:
 119  * @connection: a #GUnixConnection
 120  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore
 121  * @error: (allow-none): #GError for error reporting, or %NULL to ignore
 122  *
 123  * Receives a file descriptor from the sending end of the connection.
 124  * The sending end has to call g_unix_connection_send_fd() for this
 125  * to work.
 126  *
 127  * As well as reading the fd this also reads a single byte from the
 128  * stream, as this is required for fd passing to work on some
 129  * implementations.
 130  *
 131  * Returns: a file descriptor on success, -1 on error.
 132  *
 133  * Since: 2.22
 134  **/
 135 gint
 136 g_unix_connection_receive_fd (GUnixConnection  *connection,
 137                               GCancellable     *cancellable,
 138                               GError          **error)
 139 {
 140   GSocketControlMessage **scms;
 141   gint *fds, nfd, fd, nscm;
 142   GUnixFDMessage *fdmsg;
 143   GSocket *socket;
 144
 145   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), -1);
 146
 147   g_object_get (connection, "socket", &socket, NULL);
 148   if (g_socket_receive_message (socket, NULL, NULL, 0,
 149                                 &scms, &nscm, NULL, cancellable, error) != 1)
 150     /* XXX it _could_ 'fail' with zero. */
 151     {
 152       g_object_unref (socket);
 153
 154       return -1;
 155     }
 156
 157   g_object_unref (socket);
 158
 159   if (nscm != 1)
 160     {
 161       gint i;
 162
 163       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 164                    _("Expecting 1 control message, got %d"), nscm);
 165
 166       for (i = 0; i < nscm; i++)
 167         g_object_unref (scms[i]);
 168
 169       g_free (scms);
 170
 171       return -1;
 172     }
 173
 174   if (!G_IS_UNIX_FD_MESSAGE (scms[0]))
 175     {
 176       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 177                            _("Unexpected type of ancillary data"));
 178       g_object_unref (scms[0]);
 179       g_free (scms);
 180
 181       return -1;
 182     }
 183
 184   fdmsg = G_UNIX_FD_MESSAGE (scms[0]);
 185   g_free (scms);
 186
 187   fds = g_unix_fd_message_steal_fds (fdmsg, &nfd);
 188   g_object_unref (fdmsg);
 189
 190   if (nfd != 1)
 191     {
 192       gint i;
 193
 194       g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 195                    _("Expecting one fd, but got %d\n"), nfd);
 196
 197       for (i = 0; i < nfd; i++)
 198         close (fds[i]);
 199
 200       g_free (fds);
 201
 202       return -1;
 203     }
 204
 205   fd = *fds;
 206   g_free (fds);
 207
 208   if (fd < 0)
 209     {
 210       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
 211                            _("Received invalid fd"));
 212       fd = -1;
 213     }
 214
 215   return fd;
 216 }
 217
 218 static void
 219 g_unix_connection_init (GUnixConnection *connection)
 220 {
 221 }
 222
 223 static void
 224 g_unix_connection_class_init (GUnixConnectionClass *class)
 225 {
 226 }
 227
 228 /* TODO: Other stuff we might want to add are:
 229 void                    g_unix_connection_send_fd_async                 (GUnixConnection      *connection,
 230                                                                          gint                  fd,
 231                                                                          gboolean              close,
 232                                                                          gint                  io_priority,
 233                                                                          GAsyncReadyCallback   callback,
 234                                                                          gpointer              user_data);
 235 gboolean                g_unix_connection_send_fd_finish                (GUnixConnection      *connection,
 236                                                                          GError              **error);
 237
 238 gboolean                g_unix_connection_send_fds                      (GUnixConnection      *connection,
 239                                                                          gint                 *fds,
 240                                                                          gint                  nfds,
 241                                                                          GError              **error);
 242 void                    g_unix_connection_send_fds_async                (GUnixConnection      *connection,
 243                                                                          gint                 *fds,
 244                                                                          gint                  nfds,
 245                                                                          gint                  io_priority,
 246                                                                          GAsyncReadyCallback   callback,
 247                                                                          gpointer              user_data);
 248 gboolean                g_unix_connection_send_fds_finish               (GUnixConnection      *connection,
 249                                                                          GError              **error);
 250
 251 void                    g_unix_connection_receive_fd_async              (GUnixConnection      *connection,
 252                                                                          gint                  io_priority,
 253                                                                          GAsyncReadyCallback   callback,
 254                                                                          gpointer              user_data);
 255 gint                    g_unix_connection_receive_fd_finish             (GUnixConnection      *connection,
 256                                                                          GError              **error);
 257
 258
 259 gboolean                g_unix_connection_send_fake_credentials         (GUnixConnection      *connection,
 260                                                                          guint64               pid,
 261                                                                          guint64               uid,
 262                                                                          guint64               gid,
 263                                                                          GError              **error);
 264 void                    g_unix_connection_send_fake_credentials_async   (GUnixConnection      *connection,
 265                                                                          guint64               pid,
 266                                                                          guint64               uid,
 267                                                                          guint64               gid,
 268                                                                          gint                  io_priority,
 269                                                                          GAsyncReadyCallback   callback,
 270                                                                          gpointer              user_data);
 271 gboolean                g_unix_connection_send_fake_credentials_finish  (GUnixConnection      *connection,
 272                                                                          GError              **error);
 273
 274 gboolean                g_unix_connection_create_pair                   (GUnixConnection     **one,
 275                                                                          GUnixConnection     **two,
 276                                                                          GError              **error);
 277 */
 278
 279
 280 /**
 281  * g_unix_connection_send_credentials:
 282  * @connection: A #GUnixConnection.
 283  * @cancellable: (allow-none): A #GCancellable or %NULL.
 284  * @error: Return location for error or %NULL.
 285  *
 286  * Passes the credentials of the current user the receiving side
 287  * of the connection. The receiving end has to call
 288  * g_unix_connection_receive_credentials() (or similar) to accept the
 289  * credentials.
 290  *
 291  * As well as sending the credentials this also writes a single NUL
 292  * byte to the stream, as this is required for credentials passing to
 293  * work on some implementations.
 294  *
 295  * Other ways to exchange credentials with a foreign peer includes the
 296  * #GUnixCredentialsMessage type and g_socket_get_credentials() function.
 297  *
 298  * Returns: %TRUE on success, %FALSE if @error is set.
 299  *
 300  * Since: 2.26
 301  */
 302 gboolean
 303 g_unix_connection_send_credentials (GUnixConnection      *connection,
 304                                     GCancellable         *cancellable,
 305                                     GError              **error)
 306 {
 307   GCredentials *credentials;
 308   GSocketControlMessage *scm;
 309   GSocket *socket;
 310   gboolean ret;
 311   GOutputVector vector;
 312   guchar nul_byte[1] = {'\0'};
 313   gint num_messages;
 314
 315   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), FALSE);
 316   g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
 317
 318   ret = FALSE;
 319
 320   credentials = g_credentials_new ();
 321
 322   vector.buffer = &nul_byte;
 323   vector.size = 1;
 324
 325   if (g_unix_credentials_message_is_supported ())
 326     {
 327       scm = g_unix_credentials_message_new_with_credentials (credentials);
 328       num_messages = 1;
 329     }
 330   else
 331     {
 332       scm = NULL;
 333       num_messages = 0;
 334     }
 335
 336   g_object_get (connection, "socket", &socket, NULL);
 337   if (g_socket_send_message (socket,
 338                              NULL, /* address */
 339                              &vector,
 340                              1,
 341                              &scm,
 342                              num_messages,
 343                              G_SOCKET_MSG_NONE,
 344                              cancellable,
 345                              error) != 1)
 346     {
 347       g_prefix_error (error, _("Error sending credentials: "));
 348       goto out;
 349     }
 350
 351   ret = TRUE;
 352
 353  out:
 354   g_object_unref (socket);
 355   if (scm != NULL)
 356     g_object_unref (scm);
 357   g_object_unref (credentials);
 358   return ret;
 359 }
 360
 361 static void
 362 send_credentials_async_thread (GSimpleAsyncResult *result,
 363                                GObject            *object,
 364                                GCancellable       *cancellable)
 365 {
 366   GError *error = NULL;
 367
 368   if (!g_unix_connection_send_credentials (G_UNIX_CONNECTION (object),
 369                                            cancellable,
 370                                            &error))
 371     {
 372       g_simple_async_result_take_error (result, error);
 373     }
 374 }
 375
 376 /**
 377  * g_unix_connection_send_credentials_async:
 378  * @connection: A #GUnixConnection.
 379  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 380  * @callback: (scope async): a #GAsyncReadyCallback to call when the request is satisfied
 381  * @user_data: (closure): the data to pass to callback function
 382  *
 383  * Asynchronously send credentials.
 384  *
 385  * For more details, see g_unix_connection_send_credentials() which is
 386  * the synchronous version of this call.
 387  *
 388  * When the operation is finished, @callback will be called. You can then call
 389  * g_unix_connection_send_credentials_finish() to get the result of the operation.
 390  *
 391  * Since: 2.32
 392  **/
 393 void
 394 g_unix_connection_send_credentials_async (GUnixConnection      *connection,
 395                                           GCancellable         *cancellable,
 396                                           GAsyncReadyCallback   callback,
 397                                           gpointer              user_data)
 398 {
 399   GSimpleAsyncResult *result;
 400
 401   result = g_simple_async_result_new (G_OBJECT (connection),
 402                                       callback, user_data,
 403                                       g_unix_connection_send_credentials_async);
 404
 405   g_simple_async_result_run_in_thread (result,
 406                                        send_credentials_async_thread,
 407                                        G_PRIORITY_DEFAULT,
 408                                        cancellable);
 409   g_object_unref (result);
 410 }
 411
 412 /**
 413  * g_unix_connection_send_credentials_finish:
 414  * @connection: A #GUnixConnection.
 415  * @result: a #GAsyncResult.
 416  * @error: a #GError, or %NULL
 417  *
 418  * Finishes an asynchronous send credentials operation started with
 419  * g_unix_connection_send_credentials_async().
 420  *
 421  * Returns: %TRUE if the operation was successful, otherwise %FALSE.
 422  *
 423  * Since: 2.32
 424  **/
 425 gboolean
 426 g_unix_connection_send_credentials_finish (GUnixConnection *connection,
 427                                            GAsyncResult    *result,
 428                                            GError         **error)
 429 {
 430   g_return_val_if_fail (
 431       g_simple_async_result_is_valid (result,
 432                                       G_OBJECT (connection),
 433                                       g_unix_connection_send_credentials_async),
 434       FALSE);
 435
 436   if (g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (result),
 437                                              error))
 438     return FALSE;
 439
 440
 441   return TRUE;
 442 }
 443
 444 /**
 445  * g_unix_connection_receive_credentials:
 446  * @connection: A #GUnixConnection.
 447  * @cancellable: (allow-none): A #GCancellable or %NULL.
 448  * @error: Return location for error or %NULL.
 449  *
 450  * Receives credentials from the sending end of the connection.  The
 451  * sending end has to call g_unix_connection_send_credentials() (or
 452  * similar) for this to work.
 453  *
 454  * As well as reading the credentials this also reads (and discards) a
 455  * single byte from the stream, as this is required for credentials
 456  * passing to work on some implementations.
 457  *
 458  * Other ways to exchange credentials with a foreign peer includes the
 459  * #GUnixCredentialsMessage type and g_socket_get_credentials() function.
 460  *
 461  * Returns: (transfer full): Received credentials on success (free with
 462  * g_object_unref()), %NULL if @error is set.
 463  *
 464  * Since: 2.26
 465  */
 466 GCredentials *
 467 g_unix_connection_receive_credentials (GUnixConnection      *connection,
 468                                        GCancellable         *cancellable,
 469                                        GError              **error)
 470 {
 471   GCredentials *ret;
 472   GSocketControlMessage **scms;
 473   gint nscm;
 474   GSocket *socket;
 475   gint n;
 476   volatile GType credentials_message_gtype;
 477   gssize num_bytes_read;
 478 #ifdef __linux__
 479   gboolean turn_off_so_passcreds;
 480 #endif
 481
 482   g_return_val_if_fail (G_IS_UNIX_CONNECTION (connection), NULL);
 483   g_return_val_if_fail (error == NULL || *error == NULL, NULL);
 484
 485   ret = NULL;
 486   scms = NULL;
 487
 488   g_object_get (connection, "socket", &socket, NULL);
 489
 490   /* On Linux, we need to turn on SO_PASSCRED if it isn't enabled
 491    * already. We also need to turn it off when we're done.  See
 492    * #617483 for more discussion.
 493    */
 494 #ifdef __linux__
 495   {
 496     gint opt_val;
 497     socklen_t opt_len;
 498
 499     turn_off_so_passcreds = FALSE;
 500     opt_val = 0;
 501     opt_len = sizeof (gint);
 502     if (getsockopt (g_socket_get_fd (socket),
 503                     SOL_SOCKET,
 504                     SO_PASSCRED,
 505                     &opt_val,
 506                     &opt_len) != 0)
 507       {
 508         g_set_error (error,
 509                      G_IO_ERROR,
 510                      g_io_error_from_errno (errno),
 511                      _("Error checking if SO_PASSCRED is enabled for socket: %s"),
 512                      strerror (errno));
 513         goto out;
 514       }
 515     if (opt_len != sizeof (gint))
 516       {
 517         g_set_error (error,
 518                      G_IO_ERROR,
 519                      G_IO_ERROR_FAILED,
 520                      _("Unexpected option length while checking if SO_PASSCRED is enabled for socket. "
 521                        "Expected %d bytes, got %d"),
 522                      (gint) sizeof (gint), (gint) opt_len);
 523         goto out;
 524       }
 525     if (opt_val == 0)
 526       {
 527         opt_val = 1;
 528         if (setsockopt (g_socket_get_fd (socket),
 529                         SOL_SOCKET,
 530                         SO_PASSCRED,
 531                         &opt_val,
 532                         sizeof opt_val) != 0)
 533           {
 534             g_set_error (error,
 535                          G_IO_ERROR,
 536                          g_io_error_from_errno (errno),
 537                          _("Error enabling SO_PASSCRED: %s"),
 538                          strerror (errno));
 539             goto out;
 540           }
 541         turn_off_so_passcreds = TRUE;
 542       }
 543   }
 544 #endif
 545
 546   /* ensure the type of GUnixCredentialsMessage has been registered with the type system */
 547   credentials_message_gtype = G_TYPE_UNIX_CREDENTIALS_MESSAGE;
 548   (credentials_message_gtype); /* To avoid -Wunused-but-set-variable */
 549   num_bytes_read = g_socket_receive_message (socket,
 550                                              NULL, /* GSocketAddress **address */
 551                                              NULL,
 552                                              0,
 553                                              &scms,
 554                                              &nscm,
 555                                              NULL,
 556                                              cancellable,
 557                                              error);
 558   if (num_bytes_read != 1)
 559     {
 560       /* Handle situation where g_socket_receive_message() returns
 561        * 0 bytes and not setting @error
 562        */
 563       if (num_bytes_read == 0 && error != NULL && *error == NULL)
 564         {
 565           g_set_error_literal (error,
 566                                G_IO_ERROR,
 567                                G_IO_ERROR_FAILED,
 568                                _("Expecting to read a single byte for receiving credentials but read zero bytes"));
 569         }
 570       goto out;
 571     }
 572
 573   if (g_unix_credentials_message_is_supported ())
 574     {
 575       if (nscm != 1)
 576         {
 577           g_set_error (error,
 578                        G_IO_ERROR,
 579                        G_IO_ERROR_FAILED,
 580                        _("Expecting 1 control message, got %d"),
 581                        nscm);
 582           goto out;
 583         }
 584
 585       if (!G_IS_UNIX_CREDENTIALS_MESSAGE (scms[0]))
 586         {
 587           g_set_error_literal (error,
 588                                G_IO_ERROR,
 589                                G_IO_ERROR_FAILED,
 590                                _("Unexpected type of ancillary data"));
 591           goto out;
 592         }
 593
 594       ret = g_unix_credentials_message_get_credentials (G_UNIX_CREDENTIALS_MESSAGE (scms[0]));
 595       g_object_ref (ret);
 596     }
 597   else
 598     {
 599       if (nscm != 0)
 600         {
 601           g_set_error (error,
 602                        G_IO_ERROR,
 603                        G_IO_ERROR_FAILED,
 604                        _("Not expecting control message, but got %d"),
 605                        nscm);
 606           goto out;
 607         }
 608       else
 609         {
 610           ret = g_socket_get_credentials (socket, error);
 611         }
 612     }
 613
 614  out:
 615
 616 #ifdef __linux__
 617   if (turn_off_so_passcreds)
 618     {
 619       gint opt_val;
 620       opt_val = 0;
 621       if (setsockopt (g_socket_get_fd (socket),
 622                       SOL_SOCKET,
 623                       SO_PASSCRED,
 624                       &opt_val,
 625                       sizeof opt_val) != 0)
 626         {
 627           g_set_error (error,
 628                        G_IO_ERROR,
 629                        g_io_error_from_errno (errno),
 630                        _("Error while disabling SO_PASSCRED: %s"),
 631                        strerror (errno));
 632           goto out;
 633         }
 634     }
 635 #endif
 636
 637   if (scms != NULL)
 638     {
 639       for (n = 0; n < nscm; n++)
 640         g_object_unref (scms[n]);
 641       g_free (scms);
 642     }
 643   g_object_unref (socket);
 644   return ret;
 645 }
 646
 647 static void
 648 receive_credentials_async_thread (GSimpleAsyncResult *result,
 649                                   GObject            *object,
 650                                   GCancellable       *cancellable)
 651 {
 652   GCredentials *creds;
 653   GError *error = NULL;
 654
 655   creds = g_unix_connection_receive_credentials (G_UNIX_CONNECTION (object),
 656                                                  cancellable,
 657                                                  &error);
 658
 659   if (creds == NULL)
 660     g_simple_async_result_take_error (result, error);
 661   else
 662     g_simple_async_result_set_op_res_gpointer (result, creds, g_object_unref);
 663 }
 664
 665 /**
 666  * g_unix_connection_receive_credentials_async:
 667  * @connection: A #GUnixConnection.
 668  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 669  * @callback: (scope async): a #GAsyncReadyCallback to call when the request is satisfied
 670  * @user_data: (closure): the data to pass to callback function
 671  *
 672  * Asynchronously receive credentials.
 673  *
 674  * For more details, see g_unix_connection_receive_credentials() which is
 675  * the synchronous version of this call.
 676  *
 677  * When the operation is finished, @callback will be called. You can then call
 678  * g_unix_connection_receive_credentials_finish() to get the result of the operation.
 679  *
 680  * Since: 2.32
 681  **/
 682 void
 683 g_unix_connection_receive_credentials_async (GUnixConnection      *connection,
 684                                               GCancellable         *cancellable,
 685                                               GAsyncReadyCallback   callback,
 686                                               gpointer              user_data)
 687 {
 688   GSimpleAsyncResult *result;
 689
 690   result = g_simple_async_result_new (G_OBJECT (connection),
 691                                       callback, user_data,
 692                                       g_unix_connection_receive_credentials_async);
 693
 694   g_simple_async_result_run_in_thread (result,
 695                                        receive_credentials_async_thread,
 696                                        G_PRIORITY_DEFAULT,
 697                                        cancellable);
 698
 699   g_object_unref (result);
 700 }
 701
 702 /**
 703  * g_unix_connection_receive_credentials_finish:
 704  * @connection: A #GUnixConnection.
 705  * @result: a #GAsyncResult.
 706  * @error: a #GError, or %NULL
 707  *
 708  * Finishes an asynchronous receive credentials operation started with
 709  * g_unix_connection_receive_credentials_async().
 710  *
 711  * Returns: (transfer full): a #GCredentials, or %NULL on error.
 712  *     Free the returned object with g_object_unref().
 713  *
 714  * Since: 2.32
 715  **/
 716 GCredentials *
 717 g_unix_connection_receive_credentials_finish (GUnixConnection *connection,
 718                                               GAsyncResult    *result,
 719                                               GError         **error)
 720 {
 721   g_return_val_if_fail (
 722       g_simple_async_result_is_valid (result,
 723                                       G_OBJECT (connection),
 724                                       g_unix_connection_receive_credentials_async),
 725       NULL);
 726
 727   if (g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (result),
 728                                              error))
 729     return NULL;
 730
 731   return g_object_ref (g_simple_async_result_get_op_res_gpointer (
 732       G_SIMPLE_ASYNC_RESULT (result)));
 733 }