gio/gkeyfilesettingsbackend.c

   1 /*
   2  * Copyright © 2010 Codethink Limited
   3  * Copyright © 2010 Novell, 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 licence, 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 Public
  16  * 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  * Authors: Vincent Untz <vuntz@gnome.org>
  21  *          Ryan Lortie <desrt@desrt.ca>
  22  */
  23
  24 #include "config.h"
  25
  26 #include <stdio.h>
  27 #include <string.h>
  28
  29 #include "gfile.h"
  30 #include "gfileinfo.h"
  31 #include "gfilemonitor.h"
  32 #include "gsimplepermission.h"
  33 #include "gsettingsbackend.h"
  34
  35 #include "gioalias.h"
  36
  37 #define G_TYPE_KEYFILE_SETTINGS_BACKEND      (g_keyfile_settings_backend_get_type ())
  38 #define G_KEYFILE_SETTINGS_BACKEND(inst)     (G_TYPE_CHECK_INSTANCE_CAST ((inst),      \
  39                                               G_TYPE_KEYFILE_SETTINGS_BACKEND,         \
  40                                               GKeyfileSettingsBackend))
  41 #define G_IS_KEYFILE_SETTINGS_BACKEND(inst)  (G_TYPE_CHECK_INSTANCE_TYPE ((inst),      \
  42                                               G_TYPE_KEYFILE_SETTINGS_BACKEND))
  43
  44
  45 typedef GSettingsBackendClass GKeyfileSettingsBackendClass;
  46
  47 typedef struct
  48 {
  49   GSettingsBackend   parent_instance;
  50
  51   GKeyFile          *keyfile;
  52   GPermission       *permission;
  53   gboolean           writable;
  54
  55   gchar             *prefix;
  56   gint               prefix_len;
  57   gchar             *root_group;
  58   gint               root_group_len;
  59
  60   GFile             *file;
  61   GFileMonitor      *file_monitor;
  62   guint8             digest[32];
  63   GFile             *dir;
  64   GFileMonitor      *dir_monitor;
  65 } GKeyfileSettingsBackend;
  66
  67 static GType g_keyfile_settings_backend_get_type (void);
  68 G_DEFINE_TYPE (GKeyfileSettingsBackend,
  69                g_keyfile_settings_backend,
  70                G_TYPE_SETTINGS_BACKEND)
  71
  72 static void
  73 compute_checksum (guint8        *digest,
  74                   gconstpointer  contents,
  75                   gsize          length)
  76 {
  77   GChecksum *checksum;
  78   gsize len = 32;
  79
  80   checksum = g_checksum_new (G_CHECKSUM_SHA256);
  81   g_checksum_update (checksum, contents, length);
  82   g_checksum_get_digest (checksum, digest, &len);
  83   g_checksum_free (checksum);
  84   g_assert (len == 32);
  85 }
  86
  87 static void
  88 g_keyfile_settings_backend_keyfile_write (GKeyfileSettingsBackend *kfsb)
  89 {
  90   gchar *contents;
  91   gsize length;
  92
  93   contents = g_key_file_to_data (kfsb->keyfile, &length, NULL);
  94   g_file_replace_contents (kfsb->file, contents, length, NULL, FALSE,
  95                            G_FILE_CREATE_REPLACE_DESTINATION,
  96                            NULL, NULL, NULL);
  97
  98   compute_checksum (kfsb->digest, contents, length);
  99   g_free (contents);
 100 }
 101
 102 static gboolean
 103 group_name_matches (const gchar *group_name,
 104                     const gchar *prefix)
 105 {
 106   /* sort of like g_str_has_prefix() except that it must be an exact
 107    * match or the prefix followed by '/'.
 108    *
 109    * for example 'a' is a prefix of 'a' and 'a/b' but not 'ab'.
 110    */
 111   gint i;
 112
 113   for (i = 0; prefix[i]; i++)
 114     if (prefix[i] != group_name[i])
 115       return FALSE;
 116
 117   return group_name[i] == '\0' || group_name[i] == '/';
 118 }
 119
 120 static gboolean
 121 convert_path (GKeyfileSettingsBackend  *kfsb,
 122               const gchar              *key,
 123               gchar                   **group,
 124               gchar                   **basename)
 125 {
 126   gint key_len = strlen (key);
 127   gint i;
 128
 129   if (key_len < kfsb->prefix_len ||
 130       memcmp (key, kfsb->prefix, kfsb->prefix_len) != 0)
 131     return FALSE;
 132
 133   key_len -= kfsb->prefix_len;
 134   key += kfsb->prefix_len;
 135
 136   for (i = key_len; i >= 0; i--)
 137     if (key[i] == '/')
 138       break;
 139
 140   if (kfsb->root_group)
 141     {
 142       /* if a root_group was specified, make sure the user hasn't given
 143        * a path that ghosts that group name
 144        */
 145       if (i == kfsb->root_group_len && memcmp (key, kfsb->root_group, i) == 0)
 146         return FALSE;
 147     }
 148   else
 149     {
 150       /* if no root_group was given, ensure that the user gave a path */
 151       if (i == -1)
 152         return FALSE;
 153     }
 154
 155   if (group)
 156     {
 157       if (i >= 0)
 158         {
 159           *group = g_memdup (key, i + 1);
 160           (*group)[i] = '\0';
 161         }
 162       else
 163         *group = g_strdup (kfsb->root_group);
 164     }
 165
 166   if (basename)
 167     *basename = g_memdup (key + i + 1, key_len - i);
 168
 169   return TRUE;
 170 }
 171
 172 gboolean
 173 path_is_valid (GKeyfileSettingsBackend *kfsb,
 174                const gchar             *path)
 175 {
 176   return convert_path (kfsb, path, NULL, NULL);
 177 }
 178
 179 static GVariant *
 180 get_from_keyfile (GKeyfileSettingsBackend *kfsb,
 181                   const GVariantType      *type,
 182                   const gchar             *key)
 183 {
 184   GVariant *return_value = NULL;
 185   gchar *group, *name;
 186
 187   if (convert_path (kfsb, key, &group, &name))
 188     {
 189       gchar *str;
 190
 191       g_assert (*name);
 192
 193       str = g_key_file_get_value (kfsb->keyfile, group, name, NULL);
 194
 195       if (str)
 196         {
 197           return_value = g_variant_parse (type, str, NULL, NULL, NULL);
 198           g_free (str);
 199         }
 200
 201       g_free (group);
 202       g_free (name);
 203     }
 204
 205   return return_value;
 206 }
 207
 208 static gboolean
 209 set_to_keyfile (GKeyfileSettingsBackend *kfsb,
 210                 const gchar             *key,
 211                 GVariant                *value)
 212 {
 213   gchar *group, *name;
 214
 215   if (convert_path (kfsb, key, &group, &name))
 216     {
 217       if (value)
 218         {
 219           gchar *str = g_variant_print (value, FALSE);
 220           g_key_file_set_value (kfsb->keyfile, group, name, str);
 221           g_variant_unref (g_variant_ref_sink (value));
 222           g_free (str);
 223         }
 224       else
 225         {
 226           if (*name == '\0')
 227             {
 228               gchar **groups;
 229               gint i;
 230
 231               groups = g_key_file_get_groups (kfsb->keyfile, NULL);
 232
 233               for (i = 0; groups[i]; i++)
 234                 if (group_name_matches (groups[i], group))
 235                   g_key_file_remove_group (kfsb->keyfile, groups[i], NULL);
 236
 237               g_strfreev (groups);
 238             }
 239           else
 240             g_key_file_remove_key (kfsb->keyfile, group, name, NULL);
 241         }
 242
 243       g_free (group);
 244       g_free (name);
 245
 246       return TRUE;
 247     }
 248
 249   return FALSE;
 250 }
 251
 252 static GVariant *
 253 g_keyfile_settings_backend_read (GSettingsBackend   *backend,
 254                                  const gchar        *key,
 255                                  const GVariantType *expected_type,
 256                                  gboolean            default_value)
 257 {
 258   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 259
 260   if (default_value)
 261     return NULL;
 262
 263   return get_from_keyfile (kfsb, expected_type, key);
 264 }
 265
 266 typedef struct
 267 {
 268   GKeyfileSettingsBackend *kfsb;
 269   gboolean failed;
 270 } WriteManyData;
 271
 272 static gboolean
 273 g_keyfile_settings_backend_write_one (gpointer key,
 274                                       gpointer value,
 275                                       gpointer user_data)
 276 {
 277   WriteManyData *data = user_data;
 278   gboolean success;
 279
 280   success = set_to_keyfile (data->kfsb, key, value);
 281   g_assert (success);
 282
 283   return FALSE;
 284 }
 285
 286 static gboolean
 287 g_keyfile_settings_backend_check_one (gpointer key,
 288                                       gpointer value,
 289                                       gpointer user_data)
 290 {
 291   WriteManyData *data = user_data;
 292
 293   return data->failed = !path_is_valid (data->kfsb, key);
 294 }
 295
 296 static gboolean
 297 g_keyfile_settings_backend_write_many (GSettingsBackend *backend,
 298                                        GTree            *tree,
 299                                        gpointer          origin_tag)
 300 {
 301   WriteManyData data = { G_KEYFILE_SETTINGS_BACKEND (backend) };
 302
 303   if (!data.kfsb->writable)
 304     return FALSE;
 305
 306   g_tree_foreach (tree, g_keyfile_settings_backend_check_one, &data);
 307
 308   if (data.failed)
 309     return FALSE;
 310
 311   g_tree_foreach (tree, g_keyfile_settings_backend_write_one, &data);
 312   g_keyfile_settings_backend_keyfile_write (data.kfsb);
 313
 314   g_settings_backend_changed_tree (backend, tree, origin_tag);
 315
 316   return TRUE;
 317 }
 318
 319 static gboolean
 320 g_keyfile_settings_backend_write (GSettingsBackend *backend,
 321                                   const gchar      *key,
 322                                   GVariant         *value,
 323                                   gpointer          origin_tag)
 324 {
 325   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 326   gboolean success;
 327
 328   if (!kfsb->writable)
 329     return FALSE;
 330
 331   success = set_to_keyfile (kfsb, key, value);
 332
 333   if (success)
 334     {
 335       g_settings_backend_changed (backend, key, origin_tag);
 336       g_keyfile_settings_backend_keyfile_write (kfsb);
 337     }
 338
 339   return success;
 340 }
 341
 342 static void
 343 g_keyfile_settings_backend_reset_path (GSettingsBackend *backend,
 344                                        const gchar      *path,
 345                                        gpointer          origin_tag)
 346 {
 347   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 348
 349   if (set_to_keyfile (kfsb, path, NULL))
 350     g_keyfile_settings_backend_keyfile_write (kfsb);
 351
 352   g_settings_backend_path_changed (backend, path, origin_tag);
 353 }
 354
 355 static void
 356 g_keyfile_settings_backend_reset (GSettingsBackend *backend,
 357                                   const gchar      *key,
 358                                   gpointer          origin_tag)
 359 {
 360   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 361
 362   if (set_to_keyfile (kfsb, key, NULL))
 363     g_keyfile_settings_backend_keyfile_write (kfsb);
 364
 365   g_settings_backend_changed (backend, key, origin_tag);
 366 }
 367
 368 static gboolean
 369 g_keyfile_settings_backend_get_writable (GSettingsBackend *backend,
 370                                          const gchar      *name)
 371 {
 372   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 373
 374   return kfsb->writable && path_is_valid (kfsb, name);
 375 }
 376
 377 static GPermission *
 378 g_keyfile_settings_backend_get_permission (GSettingsBackend *backend,
 379                                            const gchar      *path)
 380 {
 381   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 382
 383   return g_object_ref (kfsb->permission);
 384 }
 385
 386 static void
 387 keyfile_to_tree (GKeyfileSettingsBackend *kfsb,
 388                  GTree                   *tree,
 389                  GKeyFile                *keyfile,
 390                  gboolean                 dup_check)
 391 {
 392   gchar **groups;
 393   gint i;
 394
 395   groups = g_key_file_get_groups (keyfile, NULL);
 396   for (i = 0; groups[i]; i++)
 397     {
 398       gboolean is_root_group;
 399       gchar **keys;
 400       gint j;
 401
 402       is_root_group = g_strcmp0 (kfsb->root_group, groups[i]) == 0;
 403       keys = g_key_file_get_keys (keyfile, groups[i], NULL, NULL);
 404
 405       for (j = 0; keys[j]; j++)
 406         {
 407           gchar *path, *value;
 408
 409           if (is_root_group)
 410             path = g_strdup_printf ("%s%s", kfsb->prefix, keys[j]);
 411           else
 412             path = g_strdup_printf ("%s%s/%s", kfsb->prefix, groups[i], keys[j]);
 413
 414           value = g_key_file_get_value (keyfile, groups[i], keys[j], NULL);
 415
 416           if (dup_check && g_strcmp0 (g_tree_lookup (tree, path), value) == 0)
 417             {
 418               g_tree_remove (tree, path);
 419               g_free (value);
 420               g_free (path);
 421             }
 422           else
 423             g_tree_insert (tree, path, value);
 424         }
 425
 426       g_strfreev (keys);
 427     }
 428   g_strfreev (groups);
 429 }
 430
 431 static void
 432 g_keyfile_settings_backend_keyfile_reload (GKeyfileSettingsBackend *kfsb)
 433 {
 434   guint8 digest[32];
 435   gchar *contents;
 436   gsize length;
 437
 438   contents = NULL;
 439   length = 0;
 440
 441   g_file_load_contents (kfsb->file, NULL, &contents, &length, NULL, NULL);
 442   compute_checksum (digest, contents, length);
 443
 444   if (memcmp (kfsb->digest, digest, sizeof digest) != 0)
 445     {
 446       GKeyFile *keyfiles[2];
 447       GTree *tree;
 448
 449       tree = g_tree_new_full ((GCompareDataFunc) strcmp, NULL,
 450                               g_free, g_free);
 451
 452       keyfiles[0] = kfsb->keyfile;
 453       keyfiles[1] = g_key_file_new ();
 454
 455       if (length > 0)
 456         g_key_file_load_from_data (keyfiles[1], contents, length,
 457                                    G_KEY_FILE_KEEP_COMMENTS |
 458                                    G_KEY_FILE_KEEP_TRANSLATIONS, NULL);
 459
 460       keyfile_to_tree (kfsb, tree, keyfiles[0], FALSE);
 461       keyfile_to_tree (kfsb, tree, keyfiles[1], TRUE);
 462       g_key_file_free (keyfiles[0]);
 463       kfsb->keyfile = keyfiles[1];
 464
 465       if (g_tree_nnodes (tree) > 0)
 466         g_settings_backend_changed_tree (&kfsb->parent_instance, tree, NULL);
 467
 468       g_tree_unref (tree);
 469
 470       memcpy (kfsb->digest, digest, sizeof digest);
 471     }
 472
 473   g_free (contents);
 474 }
 475
 476 static void
 477 g_keyfile_settings_backend_keyfile_writable (GKeyfileSettingsBackend *kfsb)
 478 {
 479   GFileInfo *fileinfo;
 480   gboolean writable;
 481
 482   fileinfo = g_file_query_info (kfsb->dir, "access::*", 0, NULL, NULL);
 483
 484   if (fileinfo)
 485     {
 486       writable =
 487         g_file_info_get_attribute_boolean (fileinfo, G_FILE_ATTRIBUTE_ACCESS_CAN_WRITE) &&
 488         g_file_info_get_attribute_boolean (fileinfo, G_FILE_ATTRIBUTE_ACCESS_CAN_EXECUTE);
 489       g_object_unref (fileinfo);
 490     }
 491   else
 492     writable = FALSE;
 493
 494   if (writable != kfsb->writable)
 495     {
 496       kfsb->writable = writable;
 497       g_settings_backend_path_writable_changed (&kfsb->parent_instance, "/");
 498     }
 499 }
 500
 501 static void
 502 g_keyfile_settings_backend_finalize (GObject *object)
 503 {
 504   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (object);
 505
 506   g_key_file_free (kfsb->keyfile);
 507   g_object_unref (kfsb->permission);
 508
 509   g_file_monitor_cancel (kfsb->file_monitor);
 510   g_object_unref (kfsb->file_monitor);
 511   g_object_unref (kfsb->file);
 512
 513   g_file_monitor_cancel (kfsb->dir_monitor);
 514   g_object_unref (kfsb->dir_monitor);
 515   g_object_unref (kfsb->dir);
 516
 517   g_free (kfsb->root_group);
 518   g_free (kfsb->prefix);
 519
 520   G_OBJECT_CLASS (g_keyfile_settings_backend_parent_class)
 521     ->finalize (object);
 522 }
 523
 524 static void
 525 g_keyfile_settings_backend_init (GKeyfileSettingsBackend *kfsb)
 526 {
 527 }
 528
 529 static void
 530 g_keyfile_settings_backend_class_init (GKeyfileSettingsBackendClass *class)
 531 {
 532   GObjectClass *object_class = G_OBJECT_CLASS (class);
 533
 534   object_class->finalize = g_keyfile_settings_backend_finalize;
 535
 536   class->read = g_keyfile_settings_backend_read;
 537   class->write = g_keyfile_settings_backend_write;
 538   class->write_keys = g_keyfile_settings_backend_write_many;
 539   class->reset = g_keyfile_settings_backend_reset;
 540   class->reset_path = g_keyfile_settings_backend_reset_path;
 541   class->get_writable = g_keyfile_settings_backend_get_writable;
 542   class->get_permission = g_keyfile_settings_backend_get_permission;
 543   /* No need to implement subscribed/unsubscribe: the only point would be to
 544    * stop monitoring the file when there's no GSettings anymore, which is no
 545    * big win. */
 546 }
 547
 548 static void
 549 file_changed (GFileMonitor      *monitor,
 550               GFile             *file,
 551               GFile             *other_file,
 552               GFileMonitorEvent  event_type,
 553               gpointer           user_data)
 554 {
 555   GKeyfileSettingsBackend *kfsb = user_data;
 556
 557   g_keyfile_settings_backend_keyfile_reload (kfsb);
 558 }
 559
 560 static void
 561 dir_changed (GFileMonitor       *monitor,
 562               GFile             *file,
 563               GFile             *other_file,
 564               GFileMonitorEvent  event_type,
 565               gpointer           user_data)
 566 {
 567   GKeyfileSettingsBackend *kfsb = user_data;
 568
 569   g_keyfile_settings_backend_keyfile_writable (kfsb);
 570 }
 571
 572 /**
 573  * g_keyfile_settings_backend_new:
 574  * @filename: the filename of the keyfile
 575  * @root_path: the path under which all settings keys appear
 576  * @root_group: (allow-none): the group name corresponding to
 577  *              @root_path, or %NULL
 578  * Returns: a keyfile-backed #GSettingsBackend
 579  *
 580  * Creates a keyfile-backed #GSettingsBackend.
 581  *
 582  * The filename of the keyfile to use is given by @filename.
 583  *
 584  * All settings read to or written from the backend must fall under the
 585  * path given in @root_path (which must start and end with a slash and
 586  * not contain two consecutive slashes).  @root_path may be "/".
 587  *
 588  * If @root_group is non-%NULL then it specifies the name of the keyfile
 589  * group used for keys that are written directly below @root_path.  For
 590  * example, if @root_path is "/apps/example/" and @root_group is
 591  * "toplevel", then settings the key "/apps/example/enabled" to a value
 592  * of %TRUE will cause the following to appear in the keyfile:
 593  *
 594  * |[
 595  *   [toplevel]
 596  *   enabled=true
 597  * ]|
 598  *
 599  * If @root_group is %NULL then it is not permitted to store keys
 600  * directly below the @root_path.
 601  *
 602  * For keys not stored directly below @root_path (ie: in a sub-path),
 603  * the name of the subpath (with the final slash stripped) is used as
 604  * the name of the keyfile group.  To continue the example, if
 605  * "/apps/example/profiles/default/font-size" were set to
 606  * 12 then the following would appear in the keyfile:
 607  *
 608  * |[
 609  *   [profiles/default]
 610  *   font-size=12
 611  * ]|
 612  *
 613  * The backend will refuse writes (and return writability as being
 614  * %FALSE) for keys outside of @root_path and, in the event that
 615  * @root_group is %NULL, also for keys directly under @root_path.
 616  * Writes will also be refused if the backend detects that it has the
 617  * inability to rewrite the keyfile (ie: the containing directory is not
 618  * writable).
 619  *
 620  * There is no checking done for your key namespace clashing with the
 621  * syntax of the key file format.  For example, if you have '[' or ']'
 622  * characters in your path names or '=' in your key names you may be in
 623  * trouble.
 624  **/
 625 GSettingsBackend *
 626 g_keyfile_settings_backend_new (const gchar *filename,
 627                                 const gchar *root_path,
 628                                 const gchar *root_group)
 629 {
 630   GKeyfileSettingsBackend *kfsb;
 631
 632   g_return_val_if_fail (filename != NULL, NULL);
 633   g_return_val_if_fail (root_path != NULL, NULL);
 634   g_return_val_if_fail (g_str_has_prefix (root_path, "/"), NULL);
 635   g_return_val_if_fail (g_str_has_suffix (root_path, "/"), NULL);
 636   g_return_val_if_fail (strstr (root_path, "//") == NULL, NULL);
 637
 638   kfsb = g_object_new (G_TYPE_KEYFILE_SETTINGS_BACKEND, NULL);
 639   kfsb->keyfile = g_key_file_new ();
 640   kfsb->permission = g_simple_permission_new (TRUE);
 641
 642   kfsb->file = g_file_new_for_path (filename);
 643   kfsb->dir = g_file_get_parent (kfsb->file);
 644   g_file_make_directory_with_parents (kfsb->dir, NULL, NULL);
 645
 646   kfsb->file_monitor = g_file_monitor_file (kfsb->file, 0, NULL, NULL);
 647   kfsb->dir_monitor = g_file_monitor_file (kfsb->dir, 0, NULL, NULL);
 648
 649   kfsb->prefix_len = strlen (root_path);
 650   kfsb->prefix = g_strdup (root_path);
 651
 652   if (root_group)
 653     {
 654       kfsb->root_group_len = strlen (root_group);
 655       kfsb->root_group = g_strdup (root_group);
 656     }
 657
 658   compute_checksum (kfsb->digest, NULL, 0);
 659
 660   g_signal_connect (kfsb->file_monitor, "changed",
 661                     G_CALLBACK (file_changed), kfsb);
 662   g_signal_connect (kfsb->dir_monitor, "changed",
 663                     G_CALLBACK (dir_changed), kfsb);
 664
 665   g_keyfile_settings_backend_keyfile_writable (kfsb);
 666   g_keyfile_settings_backend_keyfile_reload (kfsb);
 667
 668   return G_SETTINGS_BACKEND (kfsb);
 669 }
 670
 671 #define __G_KEYFILE_SETTINGS_BACKEND_C__
 672 #include "gioaliasdef.c"