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
  36 #define G_TYPE_KEYFILE_SETTINGS_BACKEND      (g_keyfile_settings_backend_get_type ())
  37 #define G_KEYFILE_SETTINGS_BACKEND(inst)     (G_TYPE_CHECK_INSTANCE_CAST ((inst),      \
  38                                               G_TYPE_KEYFILE_SETTINGS_BACKEND,         \
  39                                               GKeyfileSettingsBackend))
  40 #define G_IS_KEYFILE_SETTINGS_BACKEND(inst)  (G_TYPE_CHECK_INSTANCE_TYPE ((inst),      \
  41                                               G_TYPE_KEYFILE_SETTINGS_BACKEND))
  42
  43
  44 typedef GSettingsBackendClass GKeyfileSettingsBackendClass;
  45
  46 typedef struct
  47 {
  48   GSettingsBackend   parent_instance;
  49
  50   GKeyFile          *keyfile;
  51   GPermission       *permission;
  52   gboolean           writable;
  53
  54   gchar             *prefix;
  55   gint               prefix_len;
  56   gchar             *root_group;
  57   gint               root_group_len;
  58
  59   GFile             *file;
  60   GFileMonitor      *file_monitor;
  61   guint8             digest[32];
  62   GFile             *dir;
  63   GFileMonitor      *dir_monitor;
  64 } GKeyfileSettingsBackend;
  65
  66 static GType g_keyfile_settings_backend_get_type (void);
  67 G_DEFINE_TYPE (GKeyfileSettingsBackend,
  68                g_keyfile_settings_backend,
  69                G_TYPE_SETTINGS_BACKEND)
  70
  71 static void
  72 compute_checksum (guint8        *digest,
  73                   gconstpointer  contents,
  74                   gsize          length)
  75 {
  76   GChecksum *checksum;
  77   gsize len = 32;
  78
  79   checksum = g_checksum_new (G_CHECKSUM_SHA256);
  80   g_checksum_update (checksum, contents, length);
  81   g_checksum_get_digest (checksum, digest, &len);
  82   g_checksum_free (checksum);
  83   g_assert (len == 32);
  84 }
  85
  86 static void
  87 g_keyfile_settings_backend_keyfile_write (GKeyfileSettingsBackend *kfsb)
  88 {
  89   gchar *contents;
  90   gsize length;
  91
  92   contents = g_key_file_to_data (kfsb->keyfile, &length, NULL);
  93   g_file_replace_contents (kfsb->file, contents, length, NULL, FALSE,
  94                            G_FILE_CREATE_REPLACE_DESTINATION,
  95                            NULL, NULL, NULL);
  96
  97   compute_checksum (kfsb->digest, contents, length);
  98   g_free (contents);
  99 }
 100
 101 static gboolean
 102 group_name_matches (const gchar *group_name,
 103                     const gchar *prefix)
 104 {
 105   /* sort of like g_str_has_prefix() except that it must be an exact
 106    * match or the prefix followed by '/'.
 107    *
 108    * for example 'a' is a prefix of 'a' and 'a/b' but not 'ab'.
 109    */
 110   gint i;
 111
 112   for (i = 0; prefix[i]; i++)
 113     if (prefix[i] != group_name[i])
 114       return FALSE;
 115
 116   return group_name[i] == '\0' || group_name[i] == '/';
 117 }
 118
 119 static gboolean
 120 convert_path (GKeyfileSettingsBackend  *kfsb,
 121               const gchar              *key,
 122               gchar                   **group,
 123               gchar                   **basename)
 124 {
 125   gint key_len = strlen (key);
 126   gint i;
 127
 128   if (key_len < kfsb->prefix_len ||
 129       memcmp (key, kfsb->prefix, kfsb->prefix_len) != 0)
 130     return FALSE;
 131
 132   key_len -= kfsb->prefix_len;
 133   key += kfsb->prefix_len;
 134
 135   for (i = key_len; i >= 0; i--)
 136     if (key[i] == '/')
 137       break;
 138
 139   if (kfsb->root_group)
 140     {
 141       /* if a root_group was specified, make sure the user hasn't given
 142        * a path that ghosts that group name
 143        */
 144       if (i == kfsb->root_group_len && memcmp (key, kfsb->root_group, i) == 0)
 145         return FALSE;
 146     }
 147   else
 148     {
 149       /* if no root_group was given, ensure that the user gave a path */
 150       if (i == -1)
 151         return FALSE;
 152     }
 153
 154   if (group)
 155     {
 156       if (i >= 0)
 157         {
 158           *group = g_memdup (key, i + 1);
 159           (*group)[i] = '\0';
 160         }
 161       else
 162         *group = g_strdup (kfsb->root_group);
 163     }
 164
 165   if (basename)
 166     *basename = g_memdup (key + i + 1, key_len - i);
 167
 168   return TRUE;
 169 }
 170
 171 gboolean
 172 path_is_valid (GKeyfileSettingsBackend *kfsb,
 173                const gchar             *path)
 174 {
 175   return convert_path (kfsb, path, NULL, NULL);
 176 }
 177
 178 static GVariant *
 179 get_from_keyfile (GKeyfileSettingsBackend *kfsb,
 180                   const GVariantType      *type,
 181                   const gchar             *key)
 182 {
 183   GVariant *return_value = NULL;
 184   gchar *group, *name;
 185
 186   if (convert_path (kfsb, key, &group, &name))
 187     {
 188       gchar *str;
 189
 190       g_assert (*name);
 191
 192       str = g_key_file_get_value (kfsb->keyfile, group, name, NULL);
 193
 194       if (str)
 195         {
 196           return_value = g_variant_parse (type, str, NULL, NULL, NULL);
 197           g_free (str);
 198         }
 199
 200       g_free (group);
 201       g_free (name);
 202     }
 203
 204   return return_value;
 205 }
 206
 207 static gboolean
 208 set_to_keyfile (GKeyfileSettingsBackend *kfsb,
 209                 const gchar             *key,
 210                 GVariant                *value)
 211 {
 212   gchar *group, *name;
 213
 214   if (convert_path (kfsb, key, &group, &name))
 215     {
 216       if (value)
 217         {
 218           gchar *str = g_variant_print (value, FALSE);
 219           g_key_file_set_value (kfsb->keyfile, group, name, str);
 220           g_variant_unref (g_variant_ref_sink (value));
 221           g_free (str);
 222         }
 223       else
 224         {
 225           if (*name == '\0')
 226             {
 227               gchar **groups;
 228               gint i;
 229
 230               groups = g_key_file_get_groups (kfsb->keyfile, NULL);
 231
 232               for (i = 0; groups[i]; i++)
 233                 if (group_name_matches (groups[i], group))
 234                   g_key_file_remove_group (kfsb->keyfile, groups[i], NULL);
 235
 236               g_strfreev (groups);
 237             }
 238           else
 239             g_key_file_remove_key (kfsb->keyfile, group, name, NULL);
 240         }
 241
 242       g_free (group);
 243       g_free (name);
 244
 245       return TRUE;
 246     }
 247
 248   return FALSE;
 249 }
 250
 251 static GVariant *
 252 g_keyfile_settings_backend_read (GSettingsBackend   *backend,
 253                                  const gchar        *key,
 254                                  const GVariantType *expected_type,
 255                                  gboolean            default_value)
 256 {
 257   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 258
 259   if (default_value)
 260     return NULL;
 261
 262   return get_from_keyfile (kfsb, expected_type, key);
 263 }
 264
 265 typedef struct
 266 {
 267   GKeyfileSettingsBackend *kfsb;
 268   gboolean failed;
 269 } WriteManyData;
 270
 271 static gboolean
 272 g_keyfile_settings_backend_write_one (gpointer key,
 273                                       gpointer value,
 274                                       gpointer user_data)
 275 {
 276   WriteManyData *data = user_data;
 277   gboolean success;
 278
 279   success = set_to_keyfile (data->kfsb, key, value);
 280   g_assert (success);
 281
 282   return FALSE;
 283 }
 284
 285 static gboolean
 286 g_keyfile_settings_backend_check_one (gpointer key,
 287                                       gpointer value,
 288                                       gpointer user_data)
 289 {
 290   WriteManyData *data = user_data;
 291
 292   return data->failed = !path_is_valid (data->kfsb, key);
 293 }
 294
 295 static gboolean
 296 g_keyfile_settings_backend_write_many (GSettingsBackend *backend,
 297                                        GTree            *tree,
 298                                        gpointer          origin_tag)
 299 {
 300   WriteManyData data = { G_KEYFILE_SETTINGS_BACKEND (backend) };
 301
 302   if (!data.kfsb->writable)
 303     return FALSE;
 304
 305   g_tree_foreach (tree, g_keyfile_settings_backend_check_one, &data);
 306
 307   if (data.failed)
 308     return FALSE;
 309
 310   g_tree_foreach (tree, g_keyfile_settings_backend_write_one, &data);
 311   g_keyfile_settings_backend_keyfile_write (data.kfsb);
 312
 313   g_settings_backend_changed_tree (backend, tree, origin_tag);
 314
 315   return TRUE;
 316 }
 317
 318 static gboolean
 319 g_keyfile_settings_backend_write (GSettingsBackend *backend,
 320                                   const gchar      *key,
 321                                   GVariant         *value,
 322                                   gpointer          origin_tag)
 323 {
 324   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 325   gboolean success;
 326
 327   if (!kfsb->writable)
 328     return FALSE;
 329
 330   success = set_to_keyfile (kfsb, key, value);
 331
 332   if (success)
 333     {
 334       g_settings_backend_changed (backend, key, origin_tag);
 335       g_keyfile_settings_backend_keyfile_write (kfsb);
 336     }
 337
 338   return success;
 339 }
 340
 341 static void
 342 g_keyfile_settings_backend_reset_path (GSettingsBackend *backend,
 343                                        const gchar      *path,
 344                                        gpointer          origin_tag)
 345 {
 346   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 347
 348   if (set_to_keyfile (kfsb, path, NULL))
 349     g_keyfile_settings_backend_keyfile_write (kfsb);
 350
 351   g_settings_backend_path_changed (backend, path, origin_tag);
 352 }
 353
 354 static void
 355 g_keyfile_settings_backend_reset (GSettingsBackend *backend,
 356                                   const gchar      *key,
 357                                   gpointer          origin_tag)
 358 {
 359   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 360
 361   if (set_to_keyfile (kfsb, key, NULL))
 362     g_keyfile_settings_backend_keyfile_write (kfsb);
 363
 364   g_settings_backend_changed (backend, key, origin_tag);
 365 }
 366
 367 static gboolean
 368 g_keyfile_settings_backend_get_writable (GSettingsBackend *backend,
 369                                          const gchar      *name)
 370 {
 371   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 372
 373   return kfsb->writable && path_is_valid (kfsb, name);
 374 }
 375
 376 static GPermission *
 377 g_keyfile_settings_backend_get_permission (GSettingsBackend *backend,
 378                                            const gchar      *path)
 379 {
 380   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (backend);
 381
 382   return g_object_ref (kfsb->permission);
 383 }
 384
 385 static void
 386 keyfile_to_tree (GKeyfileSettingsBackend *kfsb,
 387                  GTree                   *tree,
 388                  GKeyFile                *keyfile,
 389                  gboolean                 dup_check)
 390 {
 391   gchar **groups;
 392   gint i;
 393
 394   groups = g_key_file_get_groups (keyfile, NULL);
 395   for (i = 0; groups[i]; i++)
 396     {
 397       gboolean is_root_group;
 398       gchar **keys;
 399       gint j;
 400
 401       is_root_group = g_strcmp0 (kfsb->root_group, groups[i]) == 0;
 402
 403       /* reject group names that will form invalid key names */
 404       if (!is_root_group &&
 405           (g_str_has_prefix (groups[i], "/") ||
 406            g_str_has_suffix (groups[i], "/") || strstr (groups[i], "//")))
 407         continue;
 408
 409       keys = g_key_file_get_keys (keyfile, groups[i], NULL, NULL);
 410
 411       for (j = 0; keys[j]; j++)
 412         {
 413           gchar *path, *value;
 414
 415           /* reject key names with slashes in them */
 416           if (strchr (keys[j], '/'))
 417             continue;
 418
 419           if (is_root_group)
 420             path = g_strdup_printf ("%s%s", kfsb->prefix, keys[j]);
 421           else
 422             path = g_strdup_printf ("%s%s/%s", kfsb->prefix, groups[i], keys[j]);
 423
 424           value = g_key_file_get_value (keyfile, groups[i], keys[j], NULL);
 425
 426           if (dup_check && g_strcmp0 (g_tree_lookup (tree, path), value) == 0)
 427             {
 428               g_tree_remove (tree, path);
 429               g_free (value);
 430               g_free (path);
 431             }
 432           else
 433             g_tree_insert (tree, path, value);
 434         }
 435
 436       g_strfreev (keys);
 437     }
 438   g_strfreev (groups);
 439 }
 440
 441 static void
 442 g_keyfile_settings_backend_keyfile_reload (GKeyfileSettingsBackend *kfsb)
 443 {
 444   guint8 digest[32];
 445   gchar *contents;
 446   gsize length;
 447
 448   contents = NULL;
 449   length = 0;
 450
 451   g_file_load_contents (kfsb->file, NULL, &contents, &length, NULL, NULL);
 452   compute_checksum (digest, contents, length);
 453
 454   if (memcmp (kfsb->digest, digest, sizeof digest) != 0)
 455     {
 456       GKeyFile *keyfiles[2];
 457       GTree *tree;
 458
 459       tree = g_tree_new_full ((GCompareDataFunc) strcmp, NULL,
 460                               g_free, g_free);
 461
 462       keyfiles[0] = kfsb->keyfile;
 463       keyfiles[1] = g_key_file_new ();
 464
 465       if (length > 0)
 466         g_key_file_load_from_data (keyfiles[1], contents, length,
 467                                    G_KEY_FILE_KEEP_COMMENTS |
 468                                    G_KEY_FILE_KEEP_TRANSLATIONS, NULL);
 469
 470       keyfile_to_tree (kfsb, tree, keyfiles[0], FALSE);
 471       keyfile_to_tree (kfsb, tree, keyfiles[1], TRUE);
 472       g_key_file_free (keyfiles[0]);
 473       kfsb->keyfile = keyfiles[1];
 474
 475       if (g_tree_nnodes (tree) > 0)
 476         g_settings_backend_changed_tree (&kfsb->parent_instance, tree, NULL);
 477
 478       g_tree_unref (tree);
 479
 480       memcpy (kfsb->digest, digest, sizeof digest);
 481     }
 482
 483   g_free (contents);
 484 }
 485
 486 static void
 487 g_keyfile_settings_backend_keyfile_writable (GKeyfileSettingsBackend *kfsb)
 488 {
 489   GFileInfo *fileinfo;
 490   gboolean writable;
 491
 492   fileinfo = g_file_query_info (kfsb->dir, "access::*", 0, NULL, NULL);
 493
 494   if (fileinfo)
 495     {
 496       writable =
 497         g_file_info_get_attribute_boolean (fileinfo, G_FILE_ATTRIBUTE_ACCESS_CAN_WRITE) &&
 498         g_file_info_get_attribute_boolean (fileinfo, G_FILE_ATTRIBUTE_ACCESS_CAN_EXECUTE);
 499       g_object_unref (fileinfo);
 500     }
 501   else
 502     writable = FALSE;
 503
 504   if (writable != kfsb->writable)
 505     {
 506       kfsb->writable = writable;
 507       g_settings_backend_path_writable_changed (&kfsb->parent_instance, "/");
 508     }
 509 }
 510
 511 static void
 512 g_keyfile_settings_backend_finalize (GObject *object)
 513 {
 514   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (object);
 515
 516   g_key_file_free (kfsb->keyfile);
 517   g_object_unref (kfsb->permission);
 518
 519   g_file_monitor_cancel (kfsb->file_monitor);
 520   g_object_unref (kfsb->file_monitor);
 521   g_object_unref (kfsb->file);
 522
 523   g_file_monitor_cancel (kfsb->dir_monitor);
 524   g_object_unref (kfsb->dir_monitor);
 525   g_object_unref (kfsb->dir);
 526
 527   g_free (kfsb->root_group);
 528   g_free (kfsb->prefix);
 529
 530   G_OBJECT_CLASS (g_keyfile_settings_backend_parent_class)
 531     ->finalize (object);
 532 }
 533
 534 static void
 535 g_keyfile_settings_backend_init (GKeyfileSettingsBackend *kfsb)
 536 {
 537 }
 538
 539 static void
 540 g_keyfile_settings_backend_class_init (GKeyfileSettingsBackendClass *class)
 541 {
 542   GObjectClass *object_class = G_OBJECT_CLASS (class);
 543
 544   object_class->finalize = g_keyfile_settings_backend_finalize;
 545
 546   class->read = g_keyfile_settings_backend_read;
 547   class->write = g_keyfile_settings_backend_write;
 548   class->write_keys = g_keyfile_settings_backend_write_many;
 549   class->reset = g_keyfile_settings_backend_reset;
 550   class->reset_path = g_keyfile_settings_backend_reset_path;
 551   class->get_writable = g_keyfile_settings_backend_get_writable;
 552   class->get_permission = g_keyfile_settings_backend_get_permission;
 553   /* No need to implement subscribed/unsubscribe: the only point would be to
 554    * stop monitoring the file when there's no GSettings anymore, which is no
 555    * big win. */
 556 }
 557
 558 static void
 559 file_changed (GFileMonitor      *monitor,
 560               GFile             *file,
 561               GFile             *other_file,
 562               GFileMonitorEvent  event_type,
 563               gpointer           user_data)
 564 {
 565   GKeyfileSettingsBackend *kfsb = user_data;
 566
 567   g_keyfile_settings_backend_keyfile_reload (kfsb);
 568 }
 569
 570 static void
 571 dir_changed (GFileMonitor       *monitor,
 572               GFile             *file,
 573               GFile             *other_file,
 574               GFileMonitorEvent  event_type,
 575               gpointer           user_data)
 576 {
 577   GKeyfileSettingsBackend *kfsb = user_data;
 578
 579   g_keyfile_settings_backend_keyfile_writable (kfsb);
 580 }
 581
 582 /**
 583  * g_keyfile_settings_backend_new:
 584  * @filename: the filename of the keyfile
 585  * @root_path: the path under which all settings keys appear
 586  * @root_group: (allow-none): the group name corresponding to
 587  *              @root_path, or %NULL
 588  * @returns: a keyfile-backed #GSettingsBackend
 589  *
 590  * Creates a keyfile-backed #GSettingsBackend.
 591  *
 592  * The filename of the keyfile to use is given by @filename.
 593  *
 594  * All settings read to or written from the backend must fall under the
 595  * path given in @root_path (which must start and end with a slash and
 596  * not contain two consecutive slashes).  @root_path may be "/".
 597  *
 598  * If @root_group is non-%NULL then it specifies the name of the keyfile
 599  * group used for keys that are written directly below @root_path.  For
 600  * example, if @root_path is "/apps/example/" and @root_group is
 601  * "toplevel", then settings the key "/apps/example/enabled" to a value
 602  * of %TRUE will cause the following to appear in the keyfile:
 603  *
 604  * |[
 605  *   [toplevel]
 606  *   enabled=true
 607  * ]|
 608  *
 609  * If @root_group is %NULL then it is not permitted to store keys
 610  * directly below the @root_path.
 611  *
 612  * For keys not stored directly below @root_path (ie: in a sub-path),
 613  * the name of the subpath (with the final slash stripped) is used as
 614  * the name of the keyfile group.  To continue the example, if
 615  * "/apps/example/profiles/default/font-size" were set to
 616  * 12 then the following would appear in the keyfile:
 617  *
 618  * |[
 619  *   [profiles/default]
 620  *   font-size=12
 621  * ]|
 622  *
 623  * The backend will refuse writes (and return writability as being
 624  * %FALSE) for keys outside of @root_path and, in the event that
 625  * @root_group is %NULL, also for keys directly under @root_path.
 626  * Writes will also be refused if the backend detects that it has the
 627  * inability to rewrite the keyfile (ie: the containing directory is not
 628  * writable).
 629  *
 630  * There is no checking done for your key namespace clashing with the
 631  * syntax of the key file format.  For example, if you have '[' or ']'
 632  * characters in your path names or '=' in your key names you may be in
 633  * trouble.
 634  **/
 635 GSettingsBackend *
 636 g_keyfile_settings_backend_new (const gchar *filename,
 637                                 const gchar *root_path,
 638                                 const gchar *root_group)
 639 {
 640   GKeyfileSettingsBackend *kfsb;
 641
 642   g_return_val_if_fail (filename != NULL, NULL);
 643   g_return_val_if_fail (root_path != NULL, NULL);
 644   g_return_val_if_fail (g_str_has_prefix (root_path, "/"), NULL);
 645   g_return_val_if_fail (g_str_has_suffix (root_path, "/"), NULL);
 646   g_return_val_if_fail (strstr (root_path, "//") == NULL, NULL);
 647
 648   kfsb = g_object_new (G_TYPE_KEYFILE_SETTINGS_BACKEND, NULL);
 649   kfsb->keyfile = g_key_file_new ();
 650   kfsb->permission = g_simple_permission_new (TRUE);
 651
 652   kfsb->file = g_file_new_for_path (filename);
 653   kfsb->dir = g_file_get_parent (kfsb->file);
 654   g_file_make_directory_with_parents (kfsb->dir, NULL, NULL);
 655
 656   kfsb->file_monitor = g_file_monitor_file (kfsb->file, 0, NULL, NULL);
 657   kfsb->dir_monitor = g_file_monitor_file (kfsb->dir, 0, NULL, NULL);
 658
 659   kfsb->prefix_len = strlen (root_path);
 660   kfsb->prefix = g_strdup (root_path);
 661
 662   if (root_group)
 663     {
 664       kfsb->root_group_len = strlen (root_group);
 665       kfsb->root_group = g_strdup (root_group);
 666     }
 667
 668   compute_checksum (kfsb->digest, NULL, 0);
 669
 670   g_signal_connect (kfsb->file_monitor, "changed",
 671                     G_CALLBACK (file_changed), kfsb);
 672   g_signal_connect (kfsb->dir_monitor, "changed",
 673                     G_CALLBACK (dir_changed), kfsb);
 674
 675   g_keyfile_settings_backend_keyfile_writable (kfsb);
 676   g_keyfile_settings_backend_keyfile_reload (kfsb);
 677
 678   return G_SETTINGS_BACKEND (kfsb);
 679 }