gio/gvolume.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2006-2007 Red Hat, Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General
  16  * Public License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  18  * Boston, MA 02111-1307, USA.
  19  *
  20  * Author: Alexander Larsson <alexl@redhat.com>
  21  *         David Zeuthen <davidz@redhat.com>
  22  */
  23
  24 #include "config.h"
  25 #include "gmount.h"
  26 #include "gvolume.h"
  27 #include "gasyncresult.h"
  28 #include "gsimpleasyncresult.h"
  29 #include "gioerror.h"
  30 #include "glibintl.h"
  31
  32
  33 /**
  34  * SECTION:gvolume
  35  * @short_description: Volume management
  36  * @include: gio/gio.h
  37  *
  38  * The #GVolume interface represents user-visible objects that can be
  39  * mounted. Note, when porting from GnomeVFS, #GVolume is the moral
  40  * equivalent of #GnomeVFSDrive.
  41  *
  42  * Mounting a #GVolume instance is an asynchronous operation. For more
  43  * information about asynchronous operations, see #GAsyncReady and
  44  * #GSimpleAsyncReady. To mount a #GVolume, first call
  45  * g_volume_mount() with (at least) the #GVolume instance, optionally
  46  * a #GMountOperation object and a #GAsyncReadyCallback.
  47  *
  48  * Typically, one will only want to pass %NULL for the
  49  * #GMountOperation if automounting all volumes when a desktop session
  50  * starts since it's not desirable to put up a lot of dialogs asking
  51  * for credentials.
  52  *
  53  * The callback will be fired when the operation has resolved (either
  54  * with success or failure), and a #GAsyncReady structure will be
  55  * passed to the callback.  That callback should then call
  56  * g_volume_mount_finish() with the #GVolume instance and the
  57  * #GAsyncReady data to see if the operation was completed
  58  * successfully.  If an @error is present when g_volume_mount_finish()
  59  * is called, then it will be filled with any error information.
  60  *
  61  * <para id="volume-identifier">
  62  * It is sometimes necessary to directly access the underlying
  63  * operating system object behind a volume (e.g. for passing a volume
  64  * to an application via the commandline). For this purpose, GIO
  65  * allows to obtain an 'identifier' for the volume. There can be
  66  * different kinds of identifiers, such as Hal UDIs, filesystem labels,
  67  * traditional Unix devices (e.g. <filename>/dev/sda2</filename>),
  68  * uuids. GIO uses predefind strings as names for the different kinds
  69  * of identifiers: #G_VOLUME_IDENTIFIER_KIND_HAL_UDI,
  70  * #G_VOLUME_IDENTIFIER_KIND_LABEL, etc. Use g_volume_get_identifier()
  71  * to obtain an identifier for a volume.
  72  * </para>
  73  *
  74  * Note that #G_VOLUME_IDENTIFIER_KIND_HAL_UDI will only be available
  75  * when the gvfs hal volume monitor is in use. Other volume monitors
  76  * will generally be able to provide the #G_VOLUME_IDENTIFIER_KIND_UNIX_DEVICE
  77  * identifier, which can be used to obtain a hal device by means of
  78  * libhal_manger_find_device_string_match().
  79  */
  80
  81 typedef GVolumeIface GVolumeInterface;
  82 G_DEFINE_INTERFACE(GVolume, g_volume, G_TYPE_OBJECT)
  83
  84 static void
  85 g_volume_default_init (GVolumeInterface *iface)
  86 {
  87   /**
  88    * GVolume::changed:
  89    *
  90    * Emitted when the volume has been changed.
  91    **/
  92   g_signal_new (I_("changed"),
  93                 G_TYPE_VOLUME,
  94                 G_SIGNAL_RUN_LAST,
  95                 G_STRUCT_OFFSET (GVolumeIface, changed),
  96                 NULL, NULL,
  97                 g_cclosure_marshal_VOID__VOID,
  98                 G_TYPE_NONE, 0);
  99
 100   /**
 101    * GVolume::removed:
 102    *
 103    * This signal is emitted when the #GVolume have been removed. If
 104    * the recipient is holding references to the object they should
 105    * release them so the object can be finalized.
 106    **/
 107   g_signal_new (I_("removed"),
 108                 G_TYPE_VOLUME,
 109                 G_SIGNAL_RUN_LAST,
 110                 G_STRUCT_OFFSET (GVolumeIface, removed),
 111                 NULL, NULL,
 112                 g_cclosure_marshal_VOID__VOID,
 113                 G_TYPE_NONE, 0);
 114 }
 115
 116 /**
 117  * g_volume_get_name:
 118  * @volume: a #GVolume.
 119  *
 120  * Gets the name of @volume.
 121  *
 122  * Returns: the name for the given @volume. The returned string should
 123  * be freed with g_free() when no longer needed.
 124  **/
 125 char *
 126 g_volume_get_name (GVolume *volume)
 127 {
 128   GVolumeIface *iface;
 129
 130   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 131
 132   iface = G_VOLUME_GET_IFACE (volume);
 133
 134   return (* iface->get_name) (volume);
 135 }
 136
 137 /**
 138  * g_volume_get_icon:
 139  * @volume: a #GVolume.
 140  *
 141  * Gets the icon for @volume.
 142  *
 143  * Returns: (transfer full): a #GIcon.
 144  *     The returned object should be unreffed with g_object_unref()
 145  *     when no longer needed.
 146  **/
 147 GIcon *
 148 g_volume_get_icon (GVolume *volume)
 149 {
 150   GVolumeIface *iface;
 151
 152   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 153
 154   iface = G_VOLUME_GET_IFACE (volume);
 155
 156   return (* iface->get_icon) (volume);
 157 }
 158
 159 /**
 160  * g_volume_get_uuid:
 161  * @volume: a #GVolume.
 162  *
 163  * Gets the UUID for the @volume. The reference is typically based on
 164  * the file system UUID for the volume in question and should be
 165  * considered an opaque string. Returns %NULL if there is no UUID
 166  * available.
 167  *
 168  * Returns: the UUID for @volume or %NULL if no UUID can be computed.
 169  *     The returned string should be freed with g_free()
 170  *     when no longer needed.
 171  **/
 172 char *
 173 g_volume_get_uuid (GVolume *volume)
 174 {
 175   GVolumeIface *iface;
 176
 177   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 178
 179   iface = G_VOLUME_GET_IFACE (volume);
 180
 181   return (* iface->get_uuid) (volume);
 182 }
 183
 184 /**
 185  * g_volume_get_drive:
 186  * @volume: a #GVolume.
 187  *
 188  * Gets the drive for the @volume.
 189  *
 190  * Returns: (transfer full): a #GDrive or %NULL if @volume is not associated with a drive.
 191  *     The returned object should be unreffed with g_object_unref()
 192  *     when no longer needed.
 193  **/
 194 GDrive *
 195 g_volume_get_drive (GVolume *volume)
 196 {
 197   GVolumeIface *iface;
 198
 199   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 200
 201   iface = G_VOLUME_GET_IFACE (volume);
 202
 203   return (* iface->get_drive) (volume);
 204 }
 205
 206 /**
 207  * g_volume_get_mount:
 208  * @volume: a #GVolume.
 209  *
 210  * Gets the mount for the @volume.
 211  *
 212  * Returns: (transfer full): a #GMount or %NULL if @volume isn't mounted.
 213  *     The returned object should be unreffed with g_object_unref()
 214  *     when no longer needed.
 215  **/
 216 GMount *
 217 g_volume_get_mount (GVolume *volume)
 218 {
 219   GVolumeIface *iface;
 220
 221   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 222
 223   iface = G_VOLUME_GET_IFACE (volume);
 224
 225   return (* iface->get_mount) (volume);
 226 }
 227
 228
 229 /**
 230  * g_volume_can_mount:
 231  * @volume: a #GVolume.
 232  *
 233  * Checks if a volume can be mounted.
 234  *
 235  * Returns: %TRUE if the @volume can be mounted. %FALSE otherwise.
 236  **/
 237 gboolean
 238 g_volume_can_mount (GVolume *volume)
 239 {
 240   GVolumeIface *iface;
 241
 242   g_return_val_if_fail (G_IS_VOLUME (volume), FALSE);
 243
 244   iface = G_VOLUME_GET_IFACE (volume);
 245
 246   if (iface->can_mount == NULL)
 247     return FALSE;
 248
 249   return (* iface->can_mount) (volume);
 250 }
 251
 252 /**
 253  * g_volume_can_eject:
 254  * @volume: a #GVolume.
 255  *
 256  * Checks if a volume can be ejected.
 257  *
 258  * Returns: %TRUE if the @volume can be ejected. %FALSE otherwise.
 259  **/
 260 gboolean
 261 g_volume_can_eject (GVolume *volume)
 262 {
 263   GVolumeIface *iface;
 264
 265   g_return_val_if_fail (G_IS_VOLUME (volume), FALSE);
 266
 267   iface = G_VOLUME_GET_IFACE (volume);
 268
 269   if (iface->can_eject == NULL)
 270     return FALSE;
 271
 272   return (* iface->can_eject) (volume);
 273 }
 274
 275 /**
 276  * g_volume_should_automount:
 277  * @volume: a #GVolume
 278  *
 279  * Returns whether the volume should be automatically mounted.
 280  *
 281  * Returns: %TRUE if the volume should be automatically mounted.
 282  */
 283 gboolean
 284 g_volume_should_automount (GVolume *volume)
 285 {
 286   GVolumeIface *iface;
 287
 288   g_return_val_if_fail (G_IS_VOLUME (volume), FALSE);
 289
 290   iface = G_VOLUME_GET_IFACE (volume);
 291
 292   if (iface->should_automount == NULL)
 293     return FALSE;
 294
 295   return (* iface->should_automount) (volume);
 296 }
 297
 298
 299 /**
 300  * g_volume_mount:
 301  * @volume: a #GVolume.
 302  * @flags: flags affecting the operation
 303  * @mount_operation: (allow-none): a #GMountOperation or %NULL to avoid user interaction.
 304  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 305  * @callback: (allow-none): a #GAsyncReadyCallback, or %NULL.
 306  * @user_data: user data that gets passed to @callback
 307  *
 308  * Mounts a volume. This is an asynchronous operation, and is
 309  * finished by calling g_volume_mount_finish() with the @volume
 310  * and #GAsyncResult returned in the @callback.
 311  *
 312  * Virtual: mount_fn
 313  **/
 314 void
 315 g_volume_mount (GVolume             *volume,
 316                 GMountMountFlags     flags,
 317                 GMountOperation     *mount_operation,
 318                 GCancellable        *cancellable,
 319                 GAsyncReadyCallback  callback,
 320                 gpointer             user_data)
 321 {
 322   GVolumeIface *iface;
 323
 324   g_return_if_fail (G_IS_VOLUME (volume));
 325
 326   iface = G_VOLUME_GET_IFACE (volume);
 327
 328   if (iface->mount_fn == NULL)
 329     {
 330       g_simple_async_report_error_in_idle (G_OBJECT (volume), callback, user_data,
 331                                            G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 332                                            _("volume doesn't implement mount"));
 333
 334       return;
 335     }
 336
 337   (* iface->mount_fn) (volume, flags, mount_operation, cancellable, callback, user_data);
 338 }
 339
 340 /**
 341  * g_volume_mount_finish:
 342  * @volume: a #GVolume
 343  * @result: a #GAsyncResult
 344  * @error: a #GError location to store an error, or %NULL to ignore
 345  *
 346  * Finishes mounting a volume. If any errors occurred during the operation,
 347  * @error will be set to contain the errors and %FALSE will be returned.
 348  *
 349  * If the mount operation succeeded, g_volume_get_mount() on @volume
 350  * is guaranteed to return the mount right after calling this
 351  * function; there's no need to listen for the 'mount-added' signal on
 352  * #GVolumeMonitor.
 353  *
 354  * Returns: %TRUE, %FALSE if operation failed.
 355  **/
 356 gboolean
 357 g_volume_mount_finish (GVolume       *volume,
 358                        GAsyncResult  *result,
 359                        GError       **error)
 360 {
 361   GVolumeIface *iface;
 362
 363   g_return_val_if_fail (G_IS_VOLUME (volume), FALSE);
 364   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), FALSE);
 365
 366   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 367     {
 368       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (result);
 369       if (g_simple_async_result_propagate_error (simple, error))
 370         return FALSE;
 371     }
 372
 373   iface = G_VOLUME_GET_IFACE (volume);
 374   return (* iface->mount_finish) (volume, result, error);
 375 }
 376
 377 /**
 378  * g_volume_eject:
 379  * @volume: a #GVolume.
 380  * @flags: flags affecting the unmount if required for eject
 381  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 382  * @callback: (allow-none): a #GAsyncReadyCallback, or %NULL.
 383  * @user_data: user data that gets passed to @callback
 384  *
 385  * Ejects a volume. This is an asynchronous operation, and is
 386  * finished by calling g_volume_eject_finish() with the @volume
 387  * and #GAsyncResult returned in the @callback.
 388  *
 389  * Deprecated: 2.22: Use g_volume_eject_with_operation() instead.
 390  **/
 391 void
 392 g_volume_eject (GVolume             *volume,
 393                 GMountUnmountFlags   flags,
 394                 GCancellable        *cancellable,
 395                 GAsyncReadyCallback  callback,
 396                 gpointer             user_data)
 397 {
 398   GVolumeIface *iface;
 399
 400   g_return_if_fail (G_IS_VOLUME (volume));
 401
 402   iface = G_VOLUME_GET_IFACE (volume);
 403
 404   if (iface->eject == NULL)
 405     {
 406       g_simple_async_report_error_in_idle (G_OBJECT (volume), callback, user_data,
 407                                            G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 408                                            _("volume doesn't implement eject"));
 409
 410       return;
 411     }
 412
 413   (* iface->eject) (volume, flags, cancellable, callback, user_data);
 414 }
 415
 416 /**
 417  * g_volume_eject_finish:
 418  * @volume: pointer to a #GVolume.
 419  * @result: a #GAsyncResult.
 420  * @error: a #GError location to store an error, or %NULL to ignore
 421  *
 422  * Finishes ejecting a volume. If any errors occurred during the operation,
 423  * @error will be set to contain the errors and %FALSE will be returned.
 424  *
 425  * Returns: %TRUE, %FALSE if operation failed.
 426  *
 427  * Deprecated: 2.22: Use g_volume_eject_with_operation_finish() instead.
 428  **/
 429 gboolean
 430 g_volume_eject_finish (GVolume       *volume,
 431                        GAsyncResult  *result,
 432                        GError       **error)
 433 {
 434   GVolumeIface *iface;
 435
 436   g_return_val_if_fail (G_IS_VOLUME (volume), FALSE);
 437   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), FALSE);
 438
 439   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 440     {
 441       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (result);
 442       if (g_simple_async_result_propagate_error (simple, error))
 443         return FALSE;
 444     }
 445
 446   iface = G_VOLUME_GET_IFACE (volume);
 447   return (* iface->eject_finish) (volume, result, error);
 448 }
 449
 450 /**
 451  * g_volume_eject_with_operation:
 452  * @volume: a #GVolume.
 453  * @flags: flags affecting the unmount if required for eject
 454  * @mount_operation: (allow-none): a #GMountOperation or %NULL to
 455  *     avoid user interaction.
 456  * @cancellable: (allow-none): optional #GCancellable object, %NULL to ignore.
 457  * @callback: a #GAsyncReadyCallback, or %NULL.
 458  * @user_data: user data passed to @callback.
 459  *
 460  * Ejects a volume. This is an asynchronous operation, and is
 461  * finished by calling g_volume_eject_with_operation_finish() with the @volume
 462  * and #GAsyncResult data returned in the @callback.
 463  *
 464  * Since: 2.22
 465  **/
 466 void
 467 g_volume_eject_with_operation (GVolume              *volume,
 468                                GMountUnmountFlags   flags,
 469                                GMountOperation     *mount_operation,
 470                                GCancellable        *cancellable,
 471                                GAsyncReadyCallback  callback,
 472                                gpointer             user_data)
 473 {
 474   GVolumeIface *iface;
 475
 476   g_return_if_fail (G_IS_VOLUME (volume));
 477
 478   iface = G_VOLUME_GET_IFACE (volume);
 479
 480   if (iface->eject == NULL && iface->eject_with_operation == NULL)
 481     {
 482       g_simple_async_report_error_in_idle (G_OBJECT (volume),
 483                                            callback, user_data,
 484                                            G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
 485                                            /* Translators: This is an error
 486                                             * message for volume objects that
 487                                             * don't implement any of eject or eject_with_operation. */
 488                                            _("volume doesn't implement eject or eject_with_operation"));
 489       return;
 490     }
 491
 492   if (iface->eject_with_operation != NULL)
 493     (* iface->eject_with_operation) (volume, flags, mount_operation, cancellable, callback, user_data);
 494   else
 495     (* iface->eject) (volume, flags, cancellable, callback, user_data);
 496 }
 497
 498 /**
 499  * g_volume_eject_with_operation_finish:
 500  * @volume: a #GVolume.
 501  * @result: a #GAsyncResult.
 502  * @error: a #GError location to store the error occurring, or %NULL to
 503  *     ignore.
 504  *
 505  * Finishes ejecting a volume. If any errors occurred during the operation,
 506  * @error will be set to contain the errors and %FALSE will be returned.
 507  *
 508  * Returns: %TRUE if the volume was successfully ejected. %FALSE otherwise.
 509  *
 510  * Since: 2.22
 511  **/
 512 gboolean
 513 g_volume_eject_with_operation_finish (GVolume        *volume,
 514                                       GAsyncResult  *result,
 515                                       GError       **error)
 516 {
 517   GVolumeIface *iface;
 518
 519   g_return_val_if_fail (G_IS_VOLUME (volume), FALSE);
 520   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), FALSE);
 521
 522   if (G_IS_SIMPLE_ASYNC_RESULT (result))
 523     {
 524       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (result);
 525       if (g_simple_async_result_propagate_error (simple, error))
 526         return FALSE;
 527     }
 528
 529   iface = G_VOLUME_GET_IFACE (volume);
 530   if (iface->eject_with_operation_finish != NULL)
 531     return (* iface->eject_with_operation_finish) (volume, result, error);
 532   else
 533     return (* iface->eject_finish) (volume, result, error);
 534 }
 535
 536 /**
 537  * g_volume_get_identifier:
 538  * @volume: a #GVolume
 539  * @kind: the kind of identifier to return
 540  *
 541  * Gets the identifier of the given kind for @volume.
 542  * See the <link linkend="volume-identifier">introduction</link>
 543  * for more information about volume identifiers.
 544  *
 545  * Returns: a newly allocated string containing the
 546  *   requested identfier, or %NULL if the #GVolume
 547  *   doesn't have this kind of identifier
 548  */
 549 char *
 550 g_volume_get_identifier (GVolume    *volume,
 551                          const char *kind)
 552 {
 553   GVolumeIface *iface;
 554
 555   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 556   g_return_val_if_fail (kind != NULL, NULL);
 557
 558   iface = G_VOLUME_GET_IFACE (volume);
 559
 560   if (iface->get_identifier == NULL)
 561     return NULL;
 562
 563   return (* iface->get_identifier) (volume, kind);
 564 }
 565
 566 /**
 567  * g_volume_enumerate_identifiers:
 568  * @volume: a #GVolume
 569  *
 570  * Gets the kinds of <link linkend="volume-identifier">identifiers</link>
 571  * that @volume has. Use g_volume_get_identifer() to obtain
 572  * the identifiers themselves.
 573  *
 574  * Returns: (array zero-terminated=1) (transfer full): a %NULL-terminated array
 575  *   of strings containing kinds of identifiers. Use g_strfreev() to free.
 576  */
 577 char **
 578 g_volume_enumerate_identifiers (GVolume *volume)
 579 {
 580   GVolumeIface *iface;
 581
 582   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 583   iface = G_VOLUME_GET_IFACE (volume);
 584
 585   if (iface->enumerate_identifiers == NULL)
 586     return NULL;
 587
 588   return (* iface->enumerate_identifiers) (volume);
 589 }
 590
 591 /**
 592  * g_volume_get_activation_root:
 593  * @volume: a #GVolume
 594  *
 595  * Gets the activation root for a #GVolume if it is known ahead of
 596  * mount time. Returns %NULL otherwise. If not %NULL and if @volume
 597  * is mounted, then the result of g_mount_get_root() on the
 598  * #GMount object obtained from g_volume_get_mount() will always
 599  * either be equal or a prefix of what this function returns. In
 600  * other words, in code
 601  *
 602  * <programlisting>
 603  *   GMount *mount;
 604  *   GFile *mount_root
 605  *   GFile *volume_activation_root;
 606  *
 607  *   mount = g_volume_get_mount (volume); /&ast; mounted, so never NULL &ast;/
 608  *   mount_root = g_mount_get_root (mount);
 609  *   volume_activation_root = g_volume_get_activation_root(volume); /&ast; assume not NULL &ast;/
 610  * </programlisting>
 611  *
 612  * then the expression
 613  *
 614  * <programlisting>
 615  *   (g_file_has_prefix (volume_activation_root, mount_root) ||
 616       g_file_equal (volume_activation_root, mount_root))
 617  * </programlisting>
 618  *
 619  * will always be %TRUE.
 620  *
 621  * Activation roots are typically used in #GVolumeMonitor
 622  * implementations to find the underlying mount to shadow, see
 623  * g_mount_is_shadowed() for more details.
 624  *
 625  * Returns: (transfer full): the activation root of @volume or %NULL. Use
 626  * g_object_unref() to free.
 627  *
 628  * Since: 2.18
 629  **/
 630 GFile *
 631 g_volume_get_activation_root (GVolume *volume)
 632 {
 633   GVolumeIface *iface;
 634
 635   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 636   iface = G_VOLUME_GET_IFACE (volume);
 637
 638   if (iface->get_activation_root == NULL)
 639     return NULL;
 640
 641   return (* iface->get_activation_root) (volume);
 642 }
 643
 644 /**
 645  * g_volume_get_sort_key:
 646  * @volume: A #GVolume.
 647  *
 648  * Gets the sort key for @volume, if any.
 649  *
 650  * Returns: Sorting key for @volume or %NULL if no such key is available.
 651  *
 652  * Since: 2.32
 653  */
 654 const gchar *
 655 g_volume_get_sort_key (GVolume  *volume)
 656 {
 657   const gchar *ret = NULL;
 658   GVolumeIface *iface;
 659
 660   g_return_val_if_fail (G_IS_VOLUME (volume), NULL);
 661
 662   iface = G_VOLUME_GET_IFACE (volume);
 663   if (iface->get_sort_key != NULL)
 664     ret = iface->get_sort_key (volume);
 665
 666   return ret;
 667 }