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glib/gio/gregistrysettingsbackend.c
Matthias Clasen 1b28408b8b Spelling fixes 
Spelling fixes in comments and docs, provided by
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2011-08-29 14:49:32 -04:00

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/*
* 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
* preceding /.
*/
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_int16 (variant);
case 'q': return g_variant_get_uint16 (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 'x': return g_variant_get_int64 (variant);
case 't': return g_variant_get_uint64 (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, '/');
GNode *child;
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 ++;
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 preceding / */
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;
const gchar *type_string = g_variant_get_type_string (variant);
action = user_data;
self = G_REGISTRY_BACKEND (action->self);
hroot = action->hroot;
value.type = REG_NONE;
value.ptr = NULL;
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;
RegistryWrite action;
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;
}
action.self = self;
action.hroot = 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;
RegistryWrite action;
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;
}
action.self = self;
action.hroot = 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)
{
gint i;
/* 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! */
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)
{
RegistryCacheItem *item;
self->base_path = g_strdup_printf ("Software\\GSettings");
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;
}
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