[glib] Add GSettings Windows Registry backend
- From: Ryan Lortie <ryanl src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [glib] Add GSettings Windows Registry backend
- Date: Wed, 1 Sep 2010 13:05:51 +0000 (UTC)
commit 3209024c3ba730df9551074819672756477bd5aa
Author: Sam Thursfield <ssssam gmail com>
Date: Thu Aug 12 16:10:23 2010 +0100
Add GSettings Windows Registry backend
gio/Makefile.am | 7 +-
gio/giomodule.c | 4 +
gio/gregistrysettingsbackend.c | 1966 ++++++++++++++++++++++++++++++++++++++++
gio/gregistrysettingsbackend.h | 31 +
4 files changed, 2007 insertions(+), 1 deletions(-)
---
diff --git a/gio/Makefile.am b/gio/Makefile.am
index b7479e3..4618a12 100644
--- a/gio/Makefile.am
+++ b/gio/Makefile.am
@@ -128,6 +128,12 @@ settings_sources = \
gsettings-mapping.c \
gsettings.c
+if OS_WIN32
+settings_sources += \
+ gregistrysettingsbackend.h \
+ gregistrysettingsbackend.c
+endif
+
application_headers = \
gactiongroup.h \
gsimpleactiongroup.h \
@@ -142,7 +148,6 @@ application_sources = \
gsimpleaction.c \
gapplication.c
-
local_sources = \
glocaldirectorymonitor.c \
glocaldirectorymonitor.h \
diff --git a/gio/giomodule.c b/gio/giomodule.c
index 882e224..39a38ff 100644
--- a/gio/giomodule.c
+++ b/gio/giomodule.c
@@ -39,6 +39,9 @@
#ifdef G_OS_UNIX
#include "gdesktopappinfo.h"
#endif
+#ifdef G_OS_WIN32
+#include "gregistrysettingsbackend.h"
+#endif
#include <glib/gstdio.h>
/**
@@ -596,6 +599,7 @@ _g_io_modules_ensure_loaded (void)
#ifdef G_OS_WIN32
_g_win32_volume_monitor_get_type ();
g_win32_directory_monitor_get_type ();
+ g_registry_backend_get_type ();
#endif
#ifdef G_OS_UNIX
_g_unix_volume_monitor_get_type ();
diff --git a/gio/gregistrysettingsbackend.c b/gio/gregistrysettingsbackend.c
new file mode 100644
index 0000000..3e3db2e
--- /dev/null
+++ b/gio/gregistrysettingsbackend.c
@@ -0,0 +1,1966 @@
+/*
+ * Copyright © 2009-10 Sam Thursfield
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Sam Thursfield <ssssam gmail com>
+ */
+
+/* GRegistryBackend implementation notes:
+ *
+ * - All settings are stored under the path:
+ * HKEY_CURRENT_USER\Software\GSettings\
+ * This means all settings are per-user. Permissions and system-wide
+ * defaults are not implemented and will probably always be out of scope of
+ * the Windows port of GLib.
+ *
+ * - The registry type system is limited. Most GVariant types are stored as
+ * literals via g_variant_print/parse(). Strings are stored without the
+ * quotes that GVariant requires. Integer types are stored as native
+ * REG_DWORD or REG_QWORD. The REG_MULTI_SZ (string array) type could be
+ * used to avoid flattening container types.
+ *
+ * - Notifications are handled; the change event is watched for in a separate
+ * thread (Windows does not provide a callback API) which sends them with
+ * g_idle_add to the GLib main loop. The threading is done using Windows
+ * API functions, so there is no dependence on GThread.
+ *
+ * - Windows doesn't tell us which value has changed. This means we have to
+ * maintain a cache of every stored value so we can play spot the
+ * difference. This should not be a performance issue because if you are
+ * storing thousands of values in GSettings, you are probably using it
+ * wrong.
+ *
+ * - The cache stores the value as a registry type. Because many variants are
+ * stored as string representations, values which have changed equality but
+ * not equivalence may trigger spurious change notifications. GSettings
+ * users must already deal with this possibility and converting all data to
+ * GVariant values would be more effort.
+ *
+ * - Because we have to cache every registry value locally, reads are done
+ * from the cache rather than directly from the registry. Writes update
+ * both. This means that the backend will not work if the watch thread is
+ * not running. A GSettings object always subscribes to changes so we can
+ * be sure that the watch thread will be running, but if for some reason
+ * the backend is being used directly you should bear that in mind.
+ *
+ * - The registry is totally user-editable, so we are very forgiving about
+ * errors in the data we get.
+ *
+ * - The registry uses backslashes as path separators. GSettings keys only
+ * allow [A-Za-z\-] so no escaping is needed. No attempt is made to solve
+ * clashes between keys differing only in case.
+ *
+ * - RegCreateKeyA is used - Windows can also handle UTF16LE strings.
+ * GSettings doesn't pay any attention to encoding, so by using ANSI we
+ * hopefully avoid passing any invalid Unicode.
+ *
+ * - The Windows registry has the following limitations: a key may not exceed
+ * 255 characters, an entry's value may not exceed 16,383 characters, and
+ * all the values of a key may not exceed 65,535 characters.
+ *
+ * - Terminology:
+ * * in GSettings, a 'key' is eg. /desktop/gnome/background/primary-color
+ * * in the registry, the 'key' is path, which contains some 'values'.
+ * * in this file, any GSettings key is a 'key', while a registry key is
+ * termed a 'path', which contains 'values'.
+ *
+ * - My set of tests for this backend are currently at:
+ * http://gitorious.org/gsettings-gtk/gsettings-test.git
+ *
+ * - There is an undocumented function in ntdll.dll which might be more
+ * than RegNotifyChangeKeyValue(), NtNotifyChangeKey:
+ * http://source.winehq.org/source/dlls/ntdll/reg.c#L618
+ * http://undocumented.ntinternals.net/UserMode/Undocumented%20Functions/NT%20Objects/Key/NtNotifyChangeKey.html
+ *
+ * - If updating the cache ever becomes a performance issue it may make sense
+ * to use a red-black tree, but I don't currently think it's worth the time
+ */
+
+#include "config.h"
+
+#include "gregistrysettingsbackend.h"
+#include "gsimplepermission.h"
+#include "gsettingsbackend.h"
+#include "giomodule.h"
+
+
+#define _WIN32_WINNT 0x0500
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+//#define TRACE
+
+/* GSettings' limit */
+#define MAX_KEY_NAME_LENGTH 32
+
+/* Testing (on Windows XP SP3) shows that WaitForMultipleObjects fails with
+ * "The parameter is incorrect" after 64 watches. We need one for the
+ * message_sent cond, which is allowed for in the way the watches_remaining
+ * variable is used.
+ */
+#define MAX_WATCHES 64
+
+/* A watch on one registry path and its subkeys */
+typedef struct
+{
+ HANDLE event;
+ HKEY hpath;
+ char *prefix;
+ GNode *cache_node;
+} RegistryWatch;
+
+
+/* Simple message passing for the watch thread. Not enough traffic to
+ * justify a queue.
+ */
+typedef enum
+{
+ WATCH_THREAD_NONE,
+ WATCH_THREAD_ADD_WATCH,
+ WATCH_THREAD_REMOVE_WATCH,
+ WATCH_THREAD_STOP
+} WatchThreadMessageType;
+
+typedef struct
+{
+ WatchThreadMessageType type;
+ RegistryWatch watch;
+} WatchThreadMessage;
+
+
+typedef struct
+{
+ GSettingsBackend *owner;
+ HANDLE *thread;
+
+ /* Details of the things we are watching. */
+ int watches_remaining;
+ GPtrArray *events, *handles, *prefixes, *cache_nodes;
+
+ /* Communication with the main thread. Only one message is stored at a time,
+ * to make sure that messages are acknowledged before being overwritten we
+ * create two events - one is signalled when a new message is set, the
+ * other is signalled by the thread when it has processed the message.
+ */
+ WatchThreadMessage message;
+ CRITICAL_SECTION *message_lock;
+ HANDLE message_sent_event, message_received_event;
+} WatchThreadState;
+
+
+#define G_TYPE_REGISTRY_BACKEND (g_registry_backend_get_type ())
+#define G_REGISTRY_BACKEND(inst) (G_TYPE_CHECK_INSTANCE_CAST ((inst), \
+ G_TYPE_REGISTRY_BACKEND, GRegistryBackend))
+#define G_IS_REGISTRY_BACKEND(inst) (G_TYPE_CHECK_INSTANCE_TYPE ((inst), \
+ G_TYPE_REGISTRY_BACKEND))
+
+
+typedef GSettingsBackendClass GRegistryBackendClass;
+
+typedef struct {
+ GSettingsBackend parent_instance;
+
+ char *base_path;
+
+ /* A stored copy of the whole tree being watched. When we receive a change notification
+ * we have to check against this to see what has changed ... every time ...*/
+ CRITICAL_SECTION *cache_lock;
+ GNode *cache_root;
+
+ WatchThreadState *watch;
+} GRegistryBackend;
+
+G_DEFINE_TYPE_WITH_CODE (GRegistryBackend,
+ g_registry_backend,
+ G_TYPE_SETTINGS_BACKEND,
+ g_io_extension_point_implement (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,
+ g_define_type_id, "registry", 90))
+
+
+/**********************************************************************************
+ * Utility functions
+ **********************************************************************************/
+
+#include <stdio.h>
+static void
+trace (const char *format, ...)
+{
+ #ifdef TRACE
+ va_list va; va_start (va, format);
+ vprintf (format, va); fflush (stdout);
+ va_end (va);
+ #endif
+};
+
+/* g_message including a windows error message. It is not useful to have an
+ * equivalent function for g_warning because none of the registry errors can
+ * result from programmer error (Microsoft programmers don't count), instead
+ * they will mostly occur from people messing with the registry by hand. */
+static void
+g_message_win32_error (DWORD result_code,
+ const gchar *format,
+ ...)
+{
+ va_list va;
+ gint pos;
+ gchar win32_message[1024];
+
+ if (result_code == 0)
+ result_code = GetLastError ();
+
+ va_start (va, format);
+ pos = g_vsnprintf (win32_message, 512, format, va);
+
+ win32_message[pos++] = ':'; win32_message[pos++] = ' ';
+
+ FormatMessage (FORMAT_MESSAGE_FROM_SYSTEM, NULL, result_code, 0, (LPTSTR)(win32_message+pos),
+ 1023 - pos, NULL);
+
+ if (result_code == ERROR_KEY_DELETED)
+ trace ("(%s)", win32_message);
+ else
+ g_message (win32_message);
+};
+
+
+/* Make gsettings key into a registry path & value pair.
+ *
+ * Note that the return value *only* needs freeing - registry_value_name
+ * is a pointer to further inside the same block of memory.
+ */
+static gchar *
+parse_key (const gchar *key_name,
+ const gchar *registry_prefix,
+ gchar **value_name)
+{
+ gchar *path_name, *c;
+
+ /* All key paths are treated as absolute; gsettings doesn't seem to enforce a
+ * preceeding /.
+ */
+ if (key_name[0] == '/')
+ key_name ++;
+
+ if (registry_prefix == NULL)
+ path_name = g_strdup (key_name);
+ else
+ path_name = g_strjoin ("/", registry_prefix, key_name, NULL);
+
+ /* Prefix is expected to be in registry format (\ separators) so don't escape that. */
+ for (c=path_name+(registry_prefix?strlen(registry_prefix):0); *c!=0; c++)
+ if (*c == '/')
+ {
+ *c = '\\';
+ (*value_name) = c;
+ }
+
+ **value_name = 0; (*value_name)++;
+ return path_name;
+};
+
+
+static DWORD
+g_variant_get_as_dword (GVariant *variant)
+{
+ switch (g_variant_get_type_string (variant)[0])
+ {
+ case 'b': return g_variant_get_boolean (variant);
+ case 'y': return g_variant_get_byte (variant);
+ case 'n': return g_variant_get_uint16 (variant);
+ case 'q': return g_variant_get_int16 (variant);
+ case 'i': return g_variant_get_int32 (variant);
+ case 'u': return g_variant_get_uint32 (variant);
+ default: g_warn_if_reached ();
+ }
+ return 0;
+}
+
+static DWORDLONG
+g_variant_get_as_qword (GVariant *variant)
+{
+ switch (g_variant_get_type_string (variant)[0])
+ {
+ case 't': return g_variant_get_uint64 (variant);
+ case 'x': return g_variant_get_int64 (variant);
+ default: g_warn_if_reached ();
+ }
+ return 0;
+}
+
+
+static void
+handle_read_error (LONG result,
+ const gchar *path_name,
+ const gchar *value_name)
+{
+ /* file not found means key value not set, this isn't an error for us. */
+ if (result != ERROR_FILE_NOT_FOUND)
+ g_message_win32_error (result, "Unable to query value %s/%s: %s.\n",
+ path_name, value_name);
+}
+
+/***************************************************************************
+ * Cache of registry values
+ ***************************************************************************/
+
+/* Generic container for registry values */
+typedef struct {
+ DWORD type;
+
+ union {
+ gint dword; /* FIXME: could inline QWORD on 64-bit systems too */
+ void *ptr;
+ };
+} RegistryValue;
+
+static char *
+registry_value_dump (RegistryValue value)
+{
+ if (value.type == REG_DWORD)
+ return g_strdup_printf ("%i", value.dword);
+ else if (value.type == REG_QWORD)
+ return g_strdup_printf ("%I64i", value.ptr==NULL? 0: *(DWORDLONG *)value.ptr);
+ else if (value.type == REG_SZ)
+ return g_strdup_printf ("%s", (char *)value.ptr);
+ else if (value.type == REG_NONE)
+ return g_strdup_printf ("<empty>");
+ else
+ return g_strdup_printf ("<invalid>");
+}
+
+static void
+registry_value_free (RegistryValue value)
+{
+ if (value.type == REG_SZ || value.type == REG_QWORD)
+ g_free (value.ptr);
+ value.type = REG_NONE;
+ value.ptr = NULL;
+}
+
+
+/* The registry cache is stored as a tree, for easy traversal. Right now we
+ * don't sort it in a clever way. Each node corresponds to a path element
+ * ('key' in registry terms) or a value.
+ *
+ * Each subscription uses the same cache. Because GSettings can subscribe to
+ * the tree at any node any number of times, we need to reference count the
+ * nodes.
+ */
+typedef struct
+{
+ /* Component of path that this node represents */
+ gchar *name;
+
+ /* If a watch is subscribed at this point (subscription_count > 0) we can
+ * block its next notification. This is useful because if two watches cover
+ * the same path, both will trigger when it changes. It also allows changes
+ * done by the application to be ignored by the watch thread.
+ */
+ gint32 block_count : 8;
+
+ /* Number of times g_settings_subscribe has been called for this location
+ * (I guess you can't subscribe more than 16383 times) */
+ gint32 subscription_count : 14;
+
+ gint32 ref_count : 9;
+
+ gint32 touched : 1;
+ RegistryValue value;
+} RegistryCacheItem;
+
+
+
+static GNode *
+registry_cache_add_item (GNode *parent,
+ gchar *name,
+ RegistryValue value,
+ gint ref_count)
+{
+ RegistryCacheItem *item = g_slice_new (RegistryCacheItem);
+ GNode *cache_node;
+
+ g_return_val_if_fail (name != NULL, NULL);
+ g_return_val_if_fail (parent != NULL, NULL);
+
+ /* Ref count should be the number of watch points above this node */
+ item->ref_count = ref_count;
+
+ item->name = g_strdup (name);
+ item->value = value;
+ item->subscription_count = 0;
+ item->block_count = 0;
+ item->touched = FALSE;
+ trace ("\treg cache: adding %s to %s\n", name, ((RegistryCacheItem *)parent->data)->name);
+
+ cache_node = g_node_new (item);
+ g_node_append (parent, cache_node);
+ return cache_node;
+}
+
+/* The reference counting of cache tree nodes works like this: when a node is
+ * subscribed to (GSettings wants us to watch that path and everything below
+ * it) the reference count of that node and everything below is increased, as
+ * well as each parent up to the root.
+ */
+
+
+static void
+_ref_down (GNode *node)
+{
+ RegistryCacheItem *item = node->data;
+ g_node_children_foreach (node, G_TRAVERSE_ALL,
+ (GNodeForeachFunc)_ref_down, NULL);
+ item->ref_count ++;
+}
+static void
+registry_cache_ref_tree (GNode *tree)
+{
+ RegistryCacheItem *item = tree->data;
+ GNode *node = tree->parent;
+
+ g_return_if_fail (tree != NULL);
+
+ item->ref_count ++;
+
+ g_node_children_foreach (tree, G_TRAVERSE_ALL,
+ (GNodeForeachFunc)_ref_down, NULL);
+
+ for (node=tree->parent; node; node=node->parent)
+ {
+ item = node->data;
+ item->ref_count ++;
+ }
+}
+
+static void
+_free_cache_item (RegistryCacheItem *item)
+{
+ trace ("\t -- Free node %s\n", item->name);
+ g_free (item->name);
+ registry_value_free (item->value);
+ g_slice_free (RegistryCacheItem, item);
+}
+
+/* Unreferencing has to be done bottom-up */
+static void
+_unref_node (GNode *node)
+{
+ RegistryCacheItem *item = node->data;
+
+ item->ref_count --;
+
+ g_warn_if_fail (item->ref_count >= 0);
+
+ if (item->ref_count == 0)
+ {
+ _free_cache_item (item);
+ g_node_destroy (node);
+ }
+}
+
+static void
+_unref_down (GNode *node)
+{
+ g_node_children_foreach (node, G_TRAVERSE_ALL,
+ (GNodeForeachFunc)_unref_down, NULL);
+ _unref_node (node);
+}
+
+static void
+registry_cache_unref_tree (GNode *tree)
+{
+ GNode *parent = tree->parent, *next_parent;
+
+ _unref_down (tree);
+
+ while (parent)
+ {
+ next_parent = parent->parent;
+ _unref_node (parent);
+ parent = next_parent;
+ }
+}
+
+
+static void
+registry_cache_dump (GNode *cache_node,
+ gpointer data)
+{
+ RegistryCacheItem *item = cache_node->data;
+
+ int depth = GPOINTER_TO_INT(data),
+ new_depth = depth+1,
+ i;
+
+ g_return_if_fail (cache_node != NULL);
+
+ for (i=0; i<depth; i++)
+ g_print (" ");
+ if (item == NULL)
+ g_print ("*root*\n");
+ else
+ g_print ("'%s' [%i] @ %x = %s\n", item->name, item->ref_count, (guint)cache_node,
+ registry_value_dump (item->value));
+ g_node_children_foreach (cache_node, G_TRAVERSE_ALL, registry_cache_dump,
+ GINT_TO_POINTER (new_depth));
+}
+
+
+typedef struct
+{
+ gchar *name;
+ GNode *result;
+} RegistryCacheSearch;
+
+static gboolean
+registry_cache_find_compare (GNode *node,
+ gpointer data)
+{
+ RegistryCacheSearch *search = data;
+ RegistryCacheItem *item = node->data;
+
+ if (item == NULL) /* root node */
+ return FALSE;
+
+ g_return_val_if_fail (search->name != NULL, FALSE);
+ g_return_val_if_fail (item->name != NULL, FALSE);
+
+ if (strcmp (search->name, item->name) == 0)
+ {
+ search->result = node;
+ return TRUE;
+ }
+ return FALSE;
+}
+
+static GNode *
+registry_cache_find_immediate_child (GNode *node,
+ gchar *name)
+{
+ RegistryCacheSearch search;
+ search.result = NULL;
+ search.name = name;
+ g_node_traverse (node, G_POST_ORDER, G_TRAVERSE_ALL, 2,
+ registry_cache_find_compare, &search);
+ return search.result;
+}
+
+
+static GNode *
+registry_cache_get_node_for_key_recursive (GNode *node,
+ gchar *key_name,
+ gboolean create_if_not_found,
+ gint n_parent_watches)
+{
+ RegistryCacheItem *item;
+ gchar *component = key_name,
+ *c = strchr (component, '/');
+
+ if (c != NULL)
+ *c = 0;
+
+ /* We count up how many watch points we travel through finding this node,
+ * because a new node should have as many references as there are watches at
+ * points above it in the tree.
+ */
+ item = node->data;
+ if (item->subscription_count > 0)
+ n_parent_watches ++;
+
+ GNode *child = registry_cache_find_immediate_child (node, component);
+ if (child == NULL && create_if_not_found)
+ {
+ item = g_slice_new (RegistryCacheItem);
+ item->name = g_strdup (component);
+ item->value.type = REG_NONE;
+ item->value.ptr = NULL;
+ item->ref_count = n_parent_watches;
+ child = g_node_new (item);
+ g_node_append (node, child);
+ trace ("\tget node for key recursive: new %x = %s.\n", node, item->name);
+ }
+
+ /* We are done if there are no more path components. Allow for a trailing /. */
+ if (child==NULL || c == NULL || *(c+1)==0)
+ return child;
+ else
+ {
+ trace ("get node for key recursive: next: %s.\n", c+1);
+ return registry_cache_get_node_for_key_recursive
+ (child, c+1, create_if_not_found, n_parent_watches);
+ }
+}
+
+/* Look up a GSettings key in the cache. */
+static GNode *
+registry_cache_get_node_for_key (GNode *root,
+ const gchar *key_name,
+ gboolean create_if_not_found)
+{
+ GNode *child = NULL,
+ *result = NULL;
+ gchar *component, *c;
+
+ g_return_val_if_fail (key_name != NULL, NULL);
+
+ if (key_name[0] == '/')
+ key_name ++;
+
+ /* Ignore preceeding / */
+ component = g_strdup (key_name);
+ c = strchr (component, '/');
+ if (c != NULL)
+ *c = 0;
+
+ child = registry_cache_find_immediate_child (root, component);
+ if (child == NULL && create_if_not_found)
+ {
+ /* Reference count is set to 0, tree should be referenced by the caller */
+ RegistryCacheItem *item = g_slice_new (RegistryCacheItem);
+ item->value.type = REG_NONE;
+ item->value.ptr = NULL;
+ item->name = g_strdup (component);
+ item->ref_count = 0;
+ trace ("get_node_for_key: New node for component '%s'\n", item->name);
+ child = g_node_new (item);
+ g_node_append (root, child);
+ }
+
+ if (c == NULL)
+ result = root;
+ else if (*(c+1)==0)
+ result = child;
+ else if (child != NULL)
+ result = registry_cache_get_node_for_key_recursive (child, c+1, create_if_not_found, 0);
+
+ g_free (component);
+
+ return result;
+}
+
+/* Check the cache node against the registry key it represents. Return TRUE if
+ * they differ, and update the cache with the new value.
+ */
+static gboolean
+registry_cache_update_node (GNode *cache_node,
+ RegistryValue registry_value)
+{
+ RegistryCacheItem *cache_item = cache_node->data;
+
+ g_return_val_if_fail (cache_node != NULL, FALSE);
+ g_return_val_if_fail (cache_item != NULL, FALSE);
+
+ if (registry_value.type != cache_item->value.type)
+ {
+ /* The type has changed. Update cache item and register it as changed.
+ * Either the schema has changed and this is entirely legitimate, or
+ * whenever the app reads the key it will get the default value due to
+ * the type mismatch.
+ */
+ cache_item->value = registry_value;
+ return TRUE;
+ }
+
+ switch (registry_value.type)
+ {
+ case REG_DWORD:
+ {
+ if (cache_item->value.dword == registry_value.dword)
+ return FALSE;
+ else
+ {
+ cache_item->value.dword = registry_value.dword;
+ return TRUE;
+ }
+ }
+ case REG_QWORD:
+ {
+ g_return_val_if_fail (registry_value.ptr != NULL &&
+ cache_item->value.ptr != NULL, FALSE);
+
+ if (memcmp (registry_value.ptr, cache_item->value.ptr, 8)==0)
+ {
+ g_free (registry_value.ptr);
+ return FALSE;
+ }
+ else
+ {
+ g_free (cache_item->value.ptr);
+ cache_item->value.ptr = registry_value.ptr;
+ return TRUE;
+ }
+ }
+ case REG_SZ:
+ {
+ /* Value should not exist if it is NULL, an empty string is "" */
+ g_return_val_if_fail (cache_item->value.ptr != NULL, FALSE);
+ g_return_val_if_fail (registry_value.ptr != NULL, FALSE);
+
+ if (strcmp (registry_value.ptr, cache_item->value.ptr) == 0)
+ {
+ g_free (registry_value.ptr);
+ return FALSE;
+ }
+ else
+ {
+ g_free (cache_item->value.ptr);
+ cache_item->value.ptr = registry_value.ptr;
+ return TRUE;
+ }
+ }
+ default:
+ g_warning ("gregistrybackend: registry_cache_update_node: Unhandled value type :(");
+ return FALSE;
+ }
+}
+
+/* Blocking notifications is a useful optimisation. When a change is made
+ * through GSettings we update the cache manually, but a notifcation is
+ * triggered as well. This function is also used for nested notifications,
+ * eg. if /test and /test/foo are watched, and /test/foo/value is changed then
+ * we will get notified both for /test/foo and /test and it is helpful to block
+ * the second.
+ */
+static void
+registry_cache_block_notification (GNode *node)
+{
+ RegistryCacheItem *item = node->data;
+
+ g_return_if_fail (node != NULL);
+
+ if (item->subscription_count > 0)
+ item->block_count ++;
+
+ if (node->parent != NULL)
+ registry_cache_block_notification (node->parent);
+}
+
+static void
+registry_cache_destroy_tree (GNode *node,
+ WatchThreadState *self);
+
+/***************************************************************************
+ * Reading and writing
+ ***************************************************************************/
+
+static gboolean
+registry_read (HKEY hpath,
+ const gchar *path_name,
+ const gchar *value_name,
+ RegistryValue *p_value)
+{
+ LONG result;
+ DWORD value_data_size;
+ gpointer *buffer;
+
+ g_return_val_if_fail (p_value != NULL, FALSE);
+
+ p_value->type = REG_NONE;
+ p_value->ptr = NULL;
+
+ result = RegQueryValueExA (hpath, value_name, 0, &p_value->type, NULL, &value_data_size);
+ if (result != ERROR_SUCCESS)
+ {
+ handle_read_error (result, path_name, value_name);
+ return FALSE;
+ }
+
+ if (p_value->type == REG_SZ && value_data_size == 0)
+ {
+ p_value->ptr = g_strdup ("");
+ return TRUE;
+ }
+
+ if (p_value->type == REG_DWORD)
+ /* REG_DWORD is inlined */
+ buffer = (void *)&p_value->dword;
+ else
+ buffer = p_value->ptr = g_malloc (value_data_size);
+
+ result = RegQueryValueExA (hpath, value_name, 0, NULL, (LPBYTE)buffer, &value_data_size);
+ if (result != ERROR_SUCCESS)
+ {
+ handle_read_error (result, path_name, value_name);
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+
+static GVariant *
+g_registry_backend_read (GSettingsBackend *backend,
+ const gchar *key_name,
+ const GVariantType *expected_type,
+ gboolean default_value)
+{
+ GRegistryBackend *self = G_REGISTRY_BACKEND (backend);
+
+ GNode *cache_node;
+ RegistryValue registry_value;
+ GVariant *gsettings_value = NULL;
+ gchar *gsettings_type;
+
+ g_return_val_if_fail (expected_type != NULL, NULL);
+
+ if (default_value)
+ return NULL;
+
+ /* Simply read from the cache, which is updated from the registry by the
+ * watch thread as soon as changes can propagate. Any changes not yet in the
+ * cache will have the 'changed' signal emitted after this function returns.
+ */
+ EnterCriticalSection (self->cache_lock);
+ cache_node = registry_cache_get_node_for_key (self->cache_root, key_name, FALSE);
+ LeaveCriticalSection (self->cache_lock);
+
+ trace ("Reading key %s, cache node %x\n", key_name, cache_node);
+
+ /* Maybe it's not set, we can return to default */
+ if (cache_node == NULL)
+ return NULL;
+
+ trace ("\t- cached value %s\n", registry_value_dump (((RegistryCacheItem *)cache_node->data)->value));
+
+ registry_value = ((RegistryCacheItem *)cache_node->data)->value;
+
+ gsettings_type = g_variant_type_dup_string (expected_type);
+
+ /* The registry is user-editable, so we need to be fault-tolerant here. */
+ switch (gsettings_type[0])
+ {
+ case 'b': case 'y': case 'n': case 'q': case 'i': case 'u':
+ if (registry_value.type == REG_DWORD)
+ gsettings_value = g_variant_new (gsettings_type, registry_value.dword);
+ break;
+
+ case 't': case 'x':
+ if (registry_value.type == REG_QWORD)
+ {
+ DWORDLONG qword_value = *(DWORDLONG *)registry_value.ptr;
+ gsettings_value = g_variant_new (gsettings_type, qword_value);
+ }
+ break;
+
+ default:
+ if (registry_value.type == REG_SZ)
+ {
+ if (gsettings_type[0]=='s')
+ gsettings_value = g_variant_new_string ((char *)registry_value.ptr);
+ else
+ {
+ GError *error = NULL;
+ gsettings_value = g_variant_parse (expected_type, registry_value.ptr, NULL, NULL, &error);
+
+ if (error != NULL)
+ g_message ("gregistrysettingsbackend: error parsing key %s: %s\n",
+ key_name, error->message);
+ }
+ }
+ break;
+ }
+
+ g_free (gsettings_type);
+
+ return gsettings_value;
+}
+
+
+typedef struct
+{
+ GRegistryBackend *self;
+ HKEY hroot;
+} RegistryWrite;
+
+static gboolean
+g_registry_backend_write_one (const char *key_name,
+ GVariant *variant,
+ gpointer user_data)
+{
+ GRegistryBackend *self;
+ RegistryWrite *action;
+ RegistryValue value;
+
+ HKEY hroot, hpath;
+ gchar *path_name, *value_name = NULL;
+ DWORD value_data_size;
+ LPVOID value_data;
+ LONG result;
+
+ GNode *node;
+ gboolean changed;
+
+ action = user_data;
+ self = G_REGISTRY_BACKEND (action->self);
+ hroot = action->hroot;
+
+ value.type = REG_NONE;
+ value.ptr = NULL;
+
+ const gchar *type_string = g_variant_get_type_string (variant);
+ switch (type_string[0])
+ {
+ case 'b': case 'y': case 'n': case 'q': case 'i': case 'u':
+ value.type = REG_DWORD;
+ value.dword = g_variant_get_as_dword (variant);
+ value_data_size = 4;
+ value_data = &value.dword;
+ break;
+
+ case 'x': case 't':
+ value.type = REG_QWORD;
+ value.ptr = g_malloc (8);
+ *(DWORDLONG *)value.ptr = g_variant_get_as_qword (variant);
+ value_data_size = 8;
+ value_data = value.ptr;
+ break;
+
+ default:
+ value.type = REG_SZ;
+ if (type_string[0]=='s')
+ {
+ gsize length;
+ value.ptr = g_strdup (g_variant_get_string (variant, &length));
+ value_data_size = length + 1;
+ value_data = value.ptr;
+ }
+ else
+ {
+ GString *value_string;
+ value_string = g_variant_print_string (variant, NULL, FALSE);
+ value_data_size = value_string->len+1;
+ value.ptr = value_data = g_string_free (value_string, FALSE);
+ }
+ break;
+ }
+
+ /* First update the cache, because the value may not have changed and we can
+ * save a write.
+ *
+ * If 'value' has changed then its memory will not be freed by update_node(),
+ * because it will be stored in the node.
+ */
+ EnterCriticalSection (self->cache_lock);
+ node = registry_cache_get_node_for_key (self->cache_root, key_name, TRUE);
+ changed = registry_cache_update_node (node, value);
+ LeaveCriticalSection (self->cache_lock);
+
+ if (!changed)
+ return FALSE;
+
+ /* Block the next notification to any watch points above this location,
+ * because they will each get triggered on a change that is already updated
+ * in the cache.
+ */
+ registry_cache_block_notification (node);
+
+ path_name = parse_key (key_name, NULL, &value_name);
+
+ trace ("Set key: %s / %s\n", path_name, value_name);
+
+ /* Store the value in the registry */
+ result = RegCreateKeyExA (hroot, path_name, 0, NULL, 0, KEY_WRITE, NULL, &hpath, NULL);
+ if (result != ERROR_SUCCESS)
+ {
+ g_message_win32_error (result, "gregistrybackend: opening key %s failed", path_name+1);
+ registry_value_free (value);
+ g_free (path_name);
+ return FALSE;
+ }
+
+ result = RegSetValueExA (hpath, value_name, 0, value.type, value_data, value_data_size);
+ if (result != ERROR_SUCCESS)
+ g_message_win32_error (result, "gregistrybackend: setting value %s\%s\\%s failed.\n",
+ self->base_path, path_name, value_name);
+
+ /* If the write fails then it will seem like the value has changed until the
+ * next execution (because we wrote to the cache first). There's no reason
+ * for it to fail unless something is weirdly broken, however.
+ */
+
+ RegCloseKey (hpath);
+ g_free (path_name);
+
+ return FALSE;
+};
+
+/* The dconf write policy is to do the write while making out it succeeded,
+ * and then backtrack if it didn't. The registry functions are synchronous so
+ * we can't do that. */
+
+static gboolean
+g_registry_backend_write (GSettingsBackend *backend,
+ const gchar *key_name,
+ GVariant *value,
+ gpointer origin_tag)
+{
+ GRegistryBackend *self = G_REGISTRY_BACKEND (backend);
+ LONG result;
+ HKEY hroot;
+
+ result = RegCreateKeyExA (HKEY_CURRENT_USER, self->base_path, 0, NULL, 0,
+ KEY_WRITE, NULL, &hroot, NULL);
+ if (result != ERROR_SUCCESS) {
+ trace ("Error opening/creating key %s.\n", self->base_path);
+ return FALSE;
+ }
+
+ RegistryWrite action = { self, hroot };
+ g_registry_backend_write_one (key_name, value, &action);
+ g_settings_backend_changed (backend, key_name, origin_tag);
+
+ RegCloseKey (hroot);
+
+ return TRUE;
+}
+
+static gboolean
+g_registry_backend_write_tree (GSettingsBackend *backend,
+ GTree *values,
+ gpointer origin_tag)
+{
+ GRegistryBackend *self = G_REGISTRY_BACKEND (backend);
+ LONG result;
+ HKEY hroot;
+
+ result = RegCreateKeyExA (HKEY_CURRENT_USER, self->base_path, 0, NULL, 0,
+ KEY_WRITE, NULL, &hroot, NULL);
+ if (result != ERROR_SUCCESS) {
+ trace ("Error opening/creating key %s.\n", self->base_path);
+ return FALSE;
+ }
+
+ RegistryWrite action = { self, hroot };
+ g_tree_foreach (values, (GTraverseFunc)g_registry_backend_write_one,
+ &action);
+
+ g_settings_backend_changed_tree (backend, values, origin_tag);
+ RegCloseKey (hroot);
+
+ return TRUE;
+}
+
+static void
+g_registry_backend_reset (GSettingsBackend *backend,
+ const gchar *key_name,
+ gpointer origin_tag)
+{
+ GRegistryBackend *self = G_REGISTRY_BACKEND (backend);
+ gchar *path_name, *value_name = NULL;
+ GNode *cache_node;
+ LONG result;
+ HKEY hpath;
+
+ /* Remove from cache */
+ EnterCriticalSection (self->cache_lock);
+ cache_node = registry_cache_get_node_for_key (self->cache_root, key_name, FALSE);
+ if (cache_node)
+ registry_cache_destroy_tree (cache_node, self->watch);
+ LeaveCriticalSection (self->cache_lock);
+
+ /* Remove from the registry */
+ path_name = parse_key (key_name, self->base_path, &value_name);
+
+ result = RegOpenKeyExA (HKEY_CURRENT_USER, path_name, 0, KEY_SET_VALUE, &hpath);
+ if (result != ERROR_SUCCESS)
+ {
+ g_message_win32_error (result, "Registry: resetting key '%s'", path_name);
+ g_free (path_name);
+ return;
+ }
+
+ result = RegDeleteValueA (hpath, value_name);
+ RegCloseKey (hpath);
+
+ if (result != ERROR_SUCCESS)
+ {
+ g_message_win32_error (result, "Registry: resetting key '%s'", path_name);
+ g_free (path_name);
+ return;
+ }
+
+ g_free (path_name);
+
+
+ g_settings_backend_changed (backend, key_name, origin_tag);
+}
+
+/* Not implemented and probably beyond the scope of this backend */
+static gboolean
+g_registry_backend_get_writable (GSettingsBackend *backend,
+ const gchar *key_name)
+{
+ return TRUE;
+}
+
+static GPermission *
+g_registry_backend_get_permission (GSettingsBackend *backend,
+ const gchar *key_name)
+{
+ return g_simple_permission_new (TRUE);
+}
+
+
+/********************************************************************************
+ * Spot-the-difference engine
+ ********************************************************************************/
+
+static void
+_free_watch (WatchThreadState *self,
+ gint index,
+ GNode *cache_node);
+
+static void
+registry_cache_item_reset_touched (GNode *node,
+ gpointer data)
+{
+ RegistryCacheItem *item = node->data;
+ item->touched = FALSE;
+}
+
+/* Delete a node and any children, for when it has been deleted from the registry */
+static void
+registry_cache_destroy_tree (GNode *node,
+ WatchThreadState *self)
+{
+ RegistryCacheItem *item = node->data;
+
+ g_node_children_foreach (node, G_TRAVERSE_ALL,
+ (GNodeForeachFunc)registry_cache_destroy_tree, self);
+
+ if (item->subscription_count > 0)
+ {
+ /* There must be some watches active if this node is a watch point */
+ g_warn_if_fail (self->cache_nodes->len > 1);
+
+ /* This is a watch point that has been deleted. Let's free the watch! */
+ gint i;
+ for (i=1; i<self->cache_nodes->len; i++)
+ if (g_ptr_array_index (self->cache_nodes, i) == node)
+ break;
+ if (i >= self->cache_nodes->len)
+ g_warning ("watch thread: a watch point was deleted, but unable to "
+ "find '%s' in the list of %i watch nodes\n", item->name,
+ self->cache_nodes->len-1);
+ else
+ {
+ _free_watch (self, i, node);
+ g_atomic_int_inc (&self->watches_remaining);
+ }
+ }
+ _free_cache_item (node->data);
+ g_node_destroy (node);
+}
+
+static void
+registry_cache_remove_deleted (GNode *node,
+ gpointer data)
+{
+ RegistryCacheItem *item = node->data;
+
+ if (!item->touched)
+ registry_cache_destroy_tree (node, data);
+}
+
+/* Update cache from registry, and optionally report on the changes.
+ *
+ * This function is sometimes called from the watch thread, with no locking. It
+ * does call g_registry_backend functions, but this is okay because they only
+ * access self->base which is constant.
+ *
+ * When looking at this code bear in mind the terminology: in the registry, keys
+ * are containers that contain values, and other keys. Keys have a 'default'
+ * value which we always ignore.
+ *
+ * n_parent_watches: a counter used to set the reference count of any new nodes
+ * that are created - they should have as many references as
+ * there are notifications that are watching them.
+ */
+static void
+registry_cache_update (GRegistryBackend *self,
+ HKEY hpath,
+ const gchar *prefix,
+ const gchar *partial_key_name,
+ GNode *cache_node,
+ int n_watches,
+ GPtrArray *changes)
+{
+ gchar buffer[MAX_KEY_NAME_LENGTH + 1];
+ gchar *key_name;
+ gint i;
+ LONG result;
+
+ RegistryCacheItem *item = cache_node->data;
+
+ if (item->subscription_count > 0)
+ n_watches ++;
+
+ /* prefix is the level that all changes occur below; partial_key_name should
+ * be NULL on the first call to this function */
+ key_name = g_build_path ("/", prefix, partial_key_name, NULL);
+
+ trace ("registry cache update: %s. Node %x has %i children\n", key_name,
+ cache_node, g_node_n_children (cache_node));
+
+ /* Start by zeroing 'touched' flag. When the registry traversal is done, any untouched nodes
+ * must have been deleted from the registry.
+ */
+ g_node_children_foreach (cache_node, G_TRAVERSE_ALL,
+ registry_cache_item_reset_touched, NULL);
+
+ /* Recurse into each subpath at the current level, if any */
+ i = 0;
+ while (1)
+ {
+ DWORD buffer_size = MAX_KEY_NAME_LENGTH;
+ HKEY hsubpath;
+
+ result = RegEnumKeyEx (hpath, i++, buffer, &buffer_size, NULL, NULL, NULL, NULL);
+ if (result != ERROR_SUCCESS)
+ break;
+
+ result = RegOpenKeyEx (hpath, buffer, 0, KEY_READ, &hsubpath);
+ if (result == ERROR_SUCCESS)
+ {
+ GNode *subkey_node;
+ RegistryCacheItem *child_item;
+
+ subkey_node = registry_cache_find_immediate_child (cache_node, buffer);
+ if (subkey_node == NULL)
+ {
+ RegistryValue null_value = {REG_NONE, {0}};
+ subkey_node = registry_cache_add_item (cache_node, buffer,
+ null_value, n_watches);
+ }
+
+
+ registry_cache_update (self, hsubpath, prefix, buffer, subkey_node,
+ n_watches, changes);
+ child_item = subkey_node->data;
+ child_item->touched = TRUE;
+ }
+ RegCloseKey (hsubpath);
+ }
+
+ if (result != ERROR_NO_MORE_ITEMS)
+ g_message_win32_error (result, "gregistrybackend: error enumerating subkeys for cache.");
+
+ /* Enumerate each value at 'path' and check if it has changed */
+ i = 0;
+ while (1)
+ {
+ DWORD buffer_size = MAX_KEY_NAME_LENGTH;
+ GNode *cache_child_node;
+ RegistryCacheItem *child_item;
+ RegistryValue value;
+ gboolean changed = FALSE;
+
+ result = RegEnumValue (hpath, i++, buffer, &buffer_size, NULL, NULL, NULL, NULL);
+ if (result != ERROR_SUCCESS)
+ break;
+
+ if (buffer[0]==0)
+ /* This is the key's 'default' value, for which we have no use. */
+ continue;
+
+ cache_child_node = registry_cache_find_immediate_child (cache_node, buffer);
+
+ if (!registry_read (hpath, key_name, buffer, &value))
+ continue;
+
+ trace ("\tgot value %s for %s, node %x\n", registry_value_dump (value), buffer, cache_child_node);
+
+ if (cache_child_node == NULL)
+ {
+ /* This is a new value */
+ cache_child_node = registry_cache_add_item (cache_node, buffer, value,
+ n_watches);
+ changed = TRUE;
+ }
+ else
+ {
+ /* For efficiency, instead of converting every value back to a GVariant to
+ * compare it, we compare them as registry values (integers, or string
+ * representations of the variant). The spurious change notifications that may
+ * result should not be a big issue.
+ *
+ * Note that 'value' is swallowed or freed.
+ */
+ changed = registry_cache_update_node (cache_child_node, value);
+ }
+
+ child_item = cache_child_node->data;
+ child_item->touched = TRUE;
+ if (changed == TRUE && changes != NULL)
+ {
+ gchar *item;
+ if (partial_key_name == NULL)
+ item = g_strdup (buffer);
+ else
+ item = g_build_path ("/", partial_key_name, buffer, NULL);
+ g_ptr_array_add (changes, item);
+ }
+ }
+
+ if (result != ERROR_NO_MORE_ITEMS)
+ g_message_win32_error (result, "gregistrybackend: error enumerating values for cache");
+
+ /* Any nodes now left untouched must have been deleted, remove them from cache */
+ g_node_children_foreach (cache_node, G_TRAVERSE_ALL,
+ registry_cache_remove_deleted, self->watch);
+
+ trace ("registry cache update complete.\n");
+ g_free (key_name);
+};
+
+
+
+/***********************************************************************************
+ * Thread to watch for registry change events
+ ***********************************************************************************/
+
+/* Called by watch thread. Apply for notifications on a registry key and its subkeys. */
+static DWORD
+registry_watch_key (HKEY hpath, HANDLE event)
+{
+ return RegNotifyChangeKeyValue (hpath, TRUE,
+ REG_NOTIFY_CHANGE_NAME | REG_NOTIFY_CHANGE_LAST_SET,
+ event, TRUE);
+}
+
+
+/* One of these is sent down the pipe when something happens in the registry. */
+typedef struct
+{
+ GRegistryBackend *self;
+ gchar *prefix; /* prefix is a gsettings path, all items are subkeys of this. */
+ GPtrArray *items; /* each item is a subkey below prefix that has changed. */
+} RegistryEvent;
+
+/* This handler runs in the main thread to emit the changed signals */
+static gboolean
+watch_handler (RegistryEvent *event)
+{
+ gint i;
+ trace ("Watch handler: got event in %s, items %i.\n", event->prefix, event->items->len);
+
+ /* GSettings requires us to NULL-terminate the array. */
+ g_ptr_array_add (event->items, NULL);
+ g_settings_backend_keys_changed (G_SETTINGS_BACKEND (event->self), event->prefix,
+ (gchar const **)event->items->pdata, NULL);
+
+ for (i=0; i<event->items->len; i++)
+ g_free (g_ptr_array_index (event->items, i));
+ g_ptr_array_free (event->items, TRUE);
+
+ g_free (event->prefix);
+ g_object_unref (event->self);
+
+ g_slice_free (RegistryEvent, event);
+ return FALSE;
+};
+
+
+static void
+_free_watch (WatchThreadState *self,
+ gint index,
+ GNode *cache_node)
+{
+ HKEY hpath;
+ HANDLE cond;
+ gchar *prefix;
+
+ g_return_if_fail (index > 0 && index < self->events->len);
+
+ cond = g_ptr_array_index (self->events, index);
+ hpath = g_ptr_array_index (self->handles, index);
+ prefix = g_ptr_array_index (self->prefixes, index);
+
+ trace ("Freeing watch %i [%s]\n", index, prefix);
+
+ /* These can be NULL if the watch was already dead, this can happen when eg.
+ * a key is deleted but GSettings is still subscribed to it - the watch is
+ * kept alive so that the unsubscribe function works properly, but does not
+ * do anything.
+ */
+ if (hpath != NULL)
+ RegCloseKey (hpath);
+
+ if (cache_node != NULL)
+ {
+ //registry_cache_dump (G_REGISTRY_BACKEND (self->owner)->cache_root, NULL);
+ registry_cache_unref_tree (cache_node);
+ }
+
+ CloseHandle (cond);
+ g_free (prefix);
+
+ /* As long as we remove from each array at the same time, it doesn't matter that
+ * their orders get messed up - they all get messed up the same.
+ */
+ g_ptr_array_remove_index_fast (self->handles, index);
+ g_ptr_array_remove_index_fast (self->events, index);
+ g_ptr_array_remove_index_fast (self->prefixes, index);
+ g_ptr_array_remove_index_fast (self->cache_nodes, index);
+}
+
+static void
+watch_thread_handle_message (WatchThreadState *self)
+{
+ switch (self->message.type)
+ {
+ case WATCH_THREAD_NONE:
+ trace ("watch thread: you woke me up for nothin', man!");
+ break;
+
+ case WATCH_THREAD_ADD_WATCH:
+ {
+ RegistryWatch *watch = &self->message.watch;
+ LONG result;
+ result = registry_watch_key (watch->hpath, watch->event);
+ if (result == ERROR_SUCCESS)
+ {
+ g_ptr_array_add (self->events, watch->event);
+ g_ptr_array_add (self->handles, watch->hpath);
+ g_ptr_array_add (self->prefixes, watch->prefix);
+ g_ptr_array_add (self->cache_nodes, watch->cache_node);
+ trace ("watch thread: new watch on %s, %i total\n", watch->prefix,
+ self->events->len);
+ }
+ else
+ {
+ g_message_win32_error (result, "watch thread: could not watch %s", watch->prefix);
+ CloseHandle (watch->event);
+ RegCloseKey (watch->hpath);
+ g_free (watch->prefix);
+ registry_cache_unref_tree (watch->cache_node);
+ }
+ break;
+ }
+
+ case WATCH_THREAD_REMOVE_WATCH:
+ {
+ GNode *cache_node;
+ RegistryCacheItem *cache_item;
+ gint i;
+
+ for (i=1; i<self->prefixes->len; i++)
+ if (strcmp (g_ptr_array_index (self->prefixes, i),
+ self->message.watch.prefix) == 0)
+ break;
+
+ if (i >= self->prefixes->len)
+ {
+ /* Don't make a fuss if the prefix is not being watched because
+ * maybe the path was deleted so we removed the watch.
+ */
+ trace ("unsubscribe: prefix %s is not being watched [%i things are]!\n",
+ self->message.watch.prefix, self->prefixes->len);
+ g_free (self->message.watch.prefix);
+ break;
+ }
+
+ cache_node = g_ptr_array_index (self->cache_nodes, i);
+
+ trace ("watch thread: unsubscribe: freeing node %x, prefix %s, index %i\n",
+ (guint)cache_node, self->message.watch.prefix, i);
+ if (cache_node != NULL)
+ {
+ cache_item = cache_node->data;
+
+ /* There may be more than one GSettings object subscribed to this
+ * path, only free the watch when the last one unsubscribes.
+ */
+ cache_item->subscription_count --;
+ if (cache_item->subscription_count > 0)
+ break;
+ }
+
+ _free_watch (self, i, cache_node);
+ g_free (self->message.watch.prefix);
+
+ g_atomic_int_inc (&self->watches_remaining);
+ break;
+ }
+
+ case WATCH_THREAD_STOP:
+ {
+ gint i;
+
+ /* Free any remaining cache and watch handles */
+ for (i=1; i<self->events->len; i++)
+ _free_watch (self, i, g_ptr_array_index (self->cache_nodes, i));
+
+ SetEvent (self->message_received_event);
+ ExitThread (0);
+ }
+ }
+
+ self->message.type = WATCH_THREAD_NONE;
+ SetEvent (self->message_received_event);
+}
+
+
+/* Thread which watches for win32 registry events */
+static DWORD WINAPI
+watch_thread_function (LPVOID parameter)
+{
+ WatchThreadState *self = (WatchThreadState *)parameter;
+ DWORD result;
+
+ self->events = g_ptr_array_new ();
+ self->handles = g_ptr_array_new ();
+ self->prefixes = g_ptr_array_new ();
+ self->cache_nodes = g_ptr_array_new ();
+ g_ptr_array_add (self->events, self->message_sent_event);
+ g_ptr_array_add (self->handles, NULL);
+ g_ptr_array_add (self->prefixes, NULL);
+ g_ptr_array_add (self->cache_nodes, NULL);
+
+ while (1)
+ {
+ trace ("watch thread: going to sleep; %i events watched.\n", self->events->len);
+ result = WaitForMultipleObjects (self->events->len, self->events->pdata, FALSE, INFINITE);
+
+ if (result == WAIT_OBJECT_0)
+ {
+ /* A message to you. The sender (main thread) will block until we signal the received
+ * event, so there should be no danger of it sending another before we receive the
+ * first.
+ */
+ watch_thread_handle_message (self);
+ }
+ else if (result > WAIT_OBJECT_0 && result <= WAIT_OBJECT_0 + self->events->len)
+ {
+ HKEY hpath;
+ HANDLE cond;
+ gchar *prefix;
+ GNode *cache_node;
+ RegistryCacheItem *cache_item;
+ RegistryEvent *event;
+
+ /* One of our notifications has triggered. All we know is which one, and which key
+ * this is for. We do most of the processing here, because we may as well. If the
+ * registry changes further while we are processing it doesn't matter - we will then
+ * receive another change notification from the OS anyway.
+ */
+ gint notify_index = result - WAIT_OBJECT_0;
+ hpath = g_ptr_array_index (self->handles, notify_index);
+ cond = g_ptr_array_index (self->events, notify_index);
+ prefix = g_ptr_array_index (self->prefixes, notify_index);
+ cache_node = g_ptr_array_index (self->cache_nodes, notify_index);
+
+ trace ("Watch thread: notify received on prefix %i: %s.\n", notify_index, prefix);
+
+ if (cache_node == NULL)
+ {
+ /* This path has been deleted */
+ trace ("Notify received on a path that was deleted :(\n");
+ continue;
+ }
+
+ /* Firstly we need to reapply for the notification, because (what a
+ * sensible API) we won't receive any more. MSDN is pretty
+ * inconsistent on this matter:
+ * http://msdn.microsoft.com/en-us/library/ms724892%28VS.85%29.aspx
+ * http://support.microsoft.com/kb/236570
+ * But my tests (on Windows XP SP3) show that we need to reapply
+ * each time.
+ */
+ result = registry_watch_key (hpath, cond);
+
+ if (result != ERROR_SUCCESS)
+ {
+ /* Watch failed, most likely because the key has just been
+ * deleted. Free the watch and unref the cache nodes.
+ */
+ if (result != ERROR_KEY_DELETED)
+ g_message_win32_error (result, "watch thread: failed to watch %s", prefix);
+ _free_watch (self, notify_index, cache_node);
+ g_atomic_int_inc (&self->watches_remaining);
+ continue;
+ }
+
+ /* The notification may have been blocked because we just changed
+ * some data ourselves.
+ */
+ cache_item = cache_node->data;
+ if (cache_item->block_count)
+ {
+ cache_item->block_count --;
+ trace ("Watch thread: notify blocked at %s\n", prefix);
+ continue;
+ }
+
+ /* Now we update our stored cache from registry data, and find which keys have
+ * actually changed. If more changes happen while we are processing, we will get
+ * another event because we have reapplied for change notifications already.
+ *
+ * Working here rather than in the main thread is preferable because the UI is less
+ * likely to block (only when changing notification subscriptions).
+ */
+ event = g_slice_new (RegistryEvent);
+
+ event->self = G_REGISTRY_BACKEND (self->owner);
+ g_object_ref (self->owner);
+
+ event->items = g_ptr_array_new ();
+
+ EnterCriticalSection (G_REGISTRY_BACKEND (self->owner)->cache_lock);
+ registry_cache_update (G_REGISTRY_BACKEND (self->owner), hpath,
+ prefix, NULL, cache_node, 0, event->items);
+ LeaveCriticalSection (G_REGISTRY_BACKEND (self->owner)->cache_lock);
+
+ if (event->items->len > 0)
+ {
+ event->prefix = g_strdup (prefix);
+ g_idle_add ((GSourceFunc) watch_handler, event);
+ }
+ else
+ {
+ g_ptr_array_free (event->items, TRUE);
+ g_slice_free (RegistryEvent, event);
+ }
+ }
+ else
+ {
+ /* God knows what has happened */
+ g_message_win32_error (GetLastError(), "watch thread: WaitForMultipleObjects error");
+ }
+ }
+
+ return -1;
+}
+
+static gboolean
+watch_start (GRegistryBackend *self)
+{
+ WatchThreadState *watch;
+
+ g_return_val_if_fail (self->watch == NULL, FALSE);
+
+ self->cache_lock = g_slice_new (CRITICAL_SECTION);
+ InitializeCriticalSection (self->cache_lock);
+
+ watch = g_slice_new (WatchThreadState);
+ watch->owner = G_SETTINGS_BACKEND (self);
+
+ watch->watches_remaining = MAX_WATCHES;
+
+ watch->message_lock = g_slice_new (CRITICAL_SECTION);
+ InitializeCriticalSection (watch->message_lock);
+ watch->message_sent_event = CreateEvent (NULL, FALSE, FALSE, NULL);
+ watch->message_received_event = CreateEvent (NULL, FALSE, FALSE, NULL);
+ if (watch->message_sent_event == NULL || watch->message_received_event == NULL)
+ {
+ g_message_win32_error (0, "gregistrybackend: Failed to create sync objects.");
+ goto fail_1;
+ }
+
+ /* Use a small stack to make the thread more lightweight. */
+ watch->thread = CreateThread (NULL, 1024, watch_thread_function, watch, 0, NULL);
+ if (watch->thread == NULL)
+ {
+ g_message_win32_error (0, "gregistrybackend: Failed to create notify watch thread.");
+ goto fail_2;
+ }
+
+ self->watch = watch;
+
+ return TRUE;
+
+fail_2:
+ DeleteCriticalSection (self->cache_lock);
+ g_slice_free (CRITICAL_SECTION, self->cache_lock);
+ DeleteCriticalSection (watch->message_lock);
+ g_slice_free (CRITICAL_SECTION, watch->message_lock);
+ CloseHandle (watch->message_sent_event);
+ CloseHandle (watch->message_received_event);
+fail_1:
+ g_slice_free (WatchThreadState, watch);
+ return FALSE;
+}
+
+/* This function assumes you hold the message lock! */
+static void
+watch_stop_unlocked (GRegistryBackend *self)
+{
+ WatchThreadState *watch = self->watch;
+ DWORD result;
+ g_return_if_fail (watch != NULL);
+
+ watch->message.type = WATCH_THREAD_STOP;
+ SetEvent (watch->message_sent_event);
+
+ /* This is signalled as soon as the message is received. We must not return
+ * while the watch thread is still firing off callbacks. Freeing all of the
+ * memory is done in the watch thread after this is signalled.
+ */
+ result = WaitForSingleObject (watch->message_received_event, INFINITE);
+ if (result != WAIT_OBJECT_0)
+ {
+ g_warning ("gregistrybackend: unable to stop watch thread.");
+ return;
+ }
+
+ LeaveCriticalSection (watch->message_lock);
+ DeleteCriticalSection (watch->message_lock);
+ DeleteCriticalSection (self->cache_lock);
+ g_slice_free (CRITICAL_SECTION, watch->message_lock);
+ g_slice_free (CRITICAL_SECTION, self->cache_lock);
+ CloseHandle (watch->message_sent_event);
+ CloseHandle (watch->message_received_event);
+ CloseHandle (watch->thread);
+ g_slice_free (WatchThreadState, watch);
+
+ trace ("\nwatch thread: %x: all data freed.\n", self);
+ self->watch = NULL;
+};
+
+static gboolean
+watch_add_notify (GRegistryBackend *self,
+ HANDLE event,
+ HKEY hpath,
+ gchar *gsettings_prefix)
+{
+ WatchThreadState *watch = self->watch;
+ GNode *cache_node;
+ RegistryCacheItem *cache_item;
+ DWORD result;
+
+ g_return_val_if_fail (watch != NULL, FALSE);
+ trace ("watch_add_notify: prefix %s.\n", gsettings_prefix);
+
+ /* Duplicate tree into the cache in the main thread, before we add the notify: if we do it in the
+ * thread we can miss changes while we are caching.
+ */
+ EnterCriticalSection (self->cache_lock);
+ cache_node = registry_cache_get_node_for_key (self->cache_root, gsettings_prefix, TRUE);
+
+ g_return_val_if_fail (cache_node != NULL, FALSE);
+ g_return_val_if_fail (cache_node->data != NULL, FALSE);
+
+ cache_item = cache_node->data;
+
+ cache_item->subscription_count ++;
+ if (cache_item->subscription_count > 1)
+ {
+ trace ("watch_add_notify: prefix %s already watched, %i subscribers.\n",
+ gsettings_prefix, cache_item->subscription_count);
+ return FALSE;
+ }
+
+ registry_cache_ref_tree (cache_node);
+ registry_cache_update (self, hpath, gsettings_prefix, NULL, cache_node, 0, NULL);
+ //registry_cache_dump (self->cache_root, NULL);
+ LeaveCriticalSection (self->cache_lock);
+
+ EnterCriticalSection (watch->message_lock);
+ watch->message.type = WATCH_THREAD_ADD_WATCH;
+ watch->message.watch.event = event;
+ watch->message.watch.hpath = hpath;
+ watch->message.watch.prefix = gsettings_prefix;
+ watch->message.watch.cache_node = cache_node;
+
+ SetEvent (watch->message_sent_event);
+
+ /* Wait for the received event in return, to avoid sending another message before the first
+ * one was received. If it takes > 200ms there is a possible race but the worst outcome is
+ * a notification is ignored.
+ */
+ result = WaitForSingleObject (watch->message_received_event, 200);
+ #ifdef TRACE
+ if (result != WAIT_OBJECT_0)
+ trace ("watch thread is slow to respond - notification may not be added.");
+ #endif
+ LeaveCriticalSection (watch->message_lock);
+
+ return TRUE;
+};
+
+
+static void
+watch_remove_notify (GRegistryBackend *self,
+ const gchar *key_name)
+{
+ WatchThreadState *watch = self->watch;
+ LONG result;
+
+ if (self->watch == NULL)
+ /* Here we assume that the unsubscribe message is for somewhere that was
+ * deleted, and so it has already been removed and the watch thread has
+ * stopped.
+ */
+ return;
+
+ EnterCriticalSection (watch->message_lock);
+ watch->message.type = WATCH_THREAD_REMOVE_WATCH;
+ watch->message.watch.prefix = g_strdup (key_name);
+
+ SetEvent (watch->message_sent_event);
+
+ /* Wait for the received event in return, to avoid sending another message before the first
+ * one was received.
+ */
+ result = WaitForSingleObject (watch->message_received_event, INFINITE);
+
+ if (result != ERROR_SUCCESS)
+ g_warning ("unsubscribe from %s: message not acknowledged\n", key_name);
+
+ if (g_atomic_int_get (&watch->watches_remaining) >= MAX_WATCHES)
+ /* Stop it before any new ones can get added and confuse things */
+ watch_stop_unlocked (self);
+ else
+ LeaveCriticalSection (watch->message_lock);
+}
+
+/* dconf semantics are: if the key ends in /, watch the keys underneath it - if not, watch that
+ * key. Our job is easier because keys and values are separate.
+ */
+static void
+g_registry_backend_subscribe (GSettingsBackend *backend,
+ const char *key_name)
+{
+ GRegistryBackend *self = G_REGISTRY_BACKEND (backend);
+ gchar *path_name, *value_name = NULL;
+ HKEY hpath;
+ HANDLE event;
+ LONG result;
+
+ if (self->watch == NULL)
+ if (!watch_start (self))
+ return;
+
+ if (g_atomic_int_dec_and_test (&self->watch->watches_remaining))
+ {
+ g_atomic_int_inc (&self->watch->watches_remaining);
+ g_warning ("subscribe() failed: only %i different paths may be watched.\n", MAX_WATCHES);
+ return;
+ }
+
+ path_name = parse_key (key_name, self->base_path, &value_name);
+
+ /* Must check for this, otherwise strange crashes occur because the cache
+ * node that is being watched gets freed. All path names to subscribe must
+ * end in a slash!
+ */
+ if (value_name != NULL && *value_name != 0)
+ g_warning ("subscribe() failed: path must end in a /, got %s\n", key_name);
+
+ trace ("Subscribing to %s [registry %s / %s] - watch %x\n", key_name, path_name, value_name, self->watch);
+
+
+ /* Give the caller the benefit of the doubt if the key doesn't exist and create it. The caller
+ * is almost certainly a new g_settings with this path as base path. */
+ result = RegCreateKeyExA (HKEY_CURRENT_USER, path_name, 0, NULL, 0, KEY_READ, NULL, &hpath,
+ NULL);
+ g_free (path_name);
+
+ if (result != ERROR_SUCCESS)
+ {
+ g_message_win32_error (result, "gregistrybackend: Unable to subscribe to key %s.", key_name);
+ g_atomic_int_inc (&self->watch->watches_remaining);
+ return;
+ }
+
+ event = CreateEvent (NULL, FALSE, FALSE, NULL);
+ if (event == NULL)
+ {
+ g_message_win32_error (result, "gregistrybackend: CreateEvent failed.\n");
+ g_atomic_int_inc (&self->watch->watches_remaining);
+ RegCloseKey (hpath);
+ return;
+ }
+
+ /* The actual watch is added by the thread, which has to re-subscribe each time it
+ * receives a change. */
+ if (!watch_add_notify (self, event, hpath, g_strdup (key_name)))
+ g_atomic_int_inc (&self->watch->watches_remaining);
+}
+
+static void
+g_registry_backend_unsubscribe (GSettingsBackend *backend,
+ const char *key_name)
+{
+ trace ("unsubscribe: %s.\n", key_name);
+
+ watch_remove_notify (G_REGISTRY_BACKEND (backend), key_name);
+}
+
+
+/********************************************************************************
+ * Object management junk
+ ********************************************************************************/
+
+GSettingsBackend *
+g_registry_backend_new (void) {
+ return g_object_new (G_TYPE_REGISTRY_BACKEND, NULL);
+}
+
+static void
+g_registry_backend_finalize (GObject *object)
+{
+ GRegistryBackend *self = G_REGISTRY_BACKEND (object);
+ RegistryCacheItem *item;
+
+ item = self->cache_root->data;
+ g_warn_if_fail (item->ref_count == 1);
+
+ _free_cache_item (item);
+ g_node_destroy (self->cache_root);
+
+ if (self->watch != NULL)
+ {
+ EnterCriticalSection (self->watch->message_lock);
+ watch_stop_unlocked (self);
+ }
+
+ g_free (self->base_path);
+}
+
+static void
+g_registry_backend_class_init (GRegistryBackendClass *class)
+{
+ GSettingsBackendClass *backend_class = G_SETTINGS_BACKEND_CLASS (class);
+ GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+ object_class->finalize = g_registry_backend_finalize;
+
+ backend_class->read = g_registry_backend_read;
+ backend_class->write = g_registry_backend_write;
+ backend_class->write_tree = g_registry_backend_write_tree;
+ backend_class->reset = g_registry_backend_reset;
+ backend_class->get_writable = g_registry_backend_get_writable;
+ backend_class->get_permission = g_registry_backend_get_permission;
+ backend_class->subscribe = g_registry_backend_subscribe;
+ backend_class->unsubscribe = g_registry_backend_unsubscribe;
+}
+
+static void
+g_registry_backend_init (GRegistryBackend *self)
+{
+ self->base_path = g_strdup_printf ("Software\\GSettings");
+
+ RegistryCacheItem *item = g_slice_new (RegistryCacheItem);
+ item->value.type = REG_NONE;
+ item->value.ptr = NULL;
+ item->name = g_strdup ("<root>");
+ item->ref_count = 1;
+ self->cache_root = g_node_new (item);
+
+ self->watch = NULL;
+}
diff --git a/gio/gregistrysettingsbackend.h b/gio/gregistrysettingsbackend.h
new file mode 100644
index 0000000..cd7bd7c
--- /dev/null
+++ b/gio/gregistrysettingsbackend.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright © 2009-10 Sam Thursfield
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the licence, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Author: Sam Thursfield <ssssam gmail com>
+ */
+
+#ifndef __G_REGISTRY_SETTINGS_BACKEND_H__
+#define __G_REGISTRY_SETTINGS_BACKEND_H__
+
+#include <glib-object.h>
+
+G_GNUC_INTERNAL
+GType g_registry_backend_get_type (void);
+
+
+#endif /* __G_REGISTRY_SETTINGS_BACKEND_H__ */
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