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glib/gio/giomodule.c
Christian Persch 8d74c96b76 Make the memory and null settings backends public 
Bug #636806.
2011-01-05 20:31:50 +01:00

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright (C) 2006-2007 Red Hat, Inc.
*
* 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 License, 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: Alexander Larsson <alexl@redhat.com>
*/
#include "config.h"
#include <string.h>
#include "giomodule.h"
#include "giomodule-priv.h"
#include "glocalfilemonitor.h"
#include "glocaldirectorymonitor.h"
#include "gnativevolumemonitor.h"
#include "gproxyresolver.h"
#include "gproxy.h"
#include "gsettingsbackendinternal.h"
#include "gsocks4proxy.h"
#include "gsocks4aproxy.h"
#include "gsocks5proxy.h"
#include "gtlsbackend.h"
#include "gvfs.h"
#ifdef G_OS_WIN32
#include "gregistrysettingsbackend.h"
#endif
#include <glib/gstdio.h>
#undef G_DISABLE_DEPRECATED
#ifdef G_OS_UNIX
#include "gdesktopappinfo.h"
#endif
/**
* SECTION:giomodule
* @short_description: Loadable GIO Modules
* @include: gio/gio.h
*
* Provides an interface and default functions for loading and unloading
* modules. This is used internally to make GIO extensible, but can also
* be used by others to implement module loading.
*
**/
/**
* SECTION:extensionpoints
* @short_description: Extension Points
* @include: gio.h
* @see_also: <link linkend="extending-gio">Extending GIO</link>
*
* #GIOExtensionPoint provides a mechanism for modules to extend the
* functionality of the library or application that loaded it in an
* organized fashion.
*
* An extension point is identified by a name, and it may optionally
* require that any implementation must by of a certain type (or derived
* thereof). Use g_io_extension_point_register() to register an
* extension point, and g_io_extension_point_set_required_type() to
* set a required type.
*
* A module can implement an extension point by specifying the #GType
* that implements the functionality. Additionally, each implementation
* of an extension point has a name, and a priority. Use
* g_io_extension_point_implement() to implement an extension point.
*
* |[
* GIOExtensionPoint *ep;
*
* /&ast; Register an extension point &ast;/
* ep = g_io_extension_point_register ("my-extension-point");
* g_io_extension_point_set_required_type (ep, MY_TYPE_EXAMPLE);
* ]|
*
* |[
* /&ast; Implement an extension point &ast;/
* G_DEFINE_TYPE (MyExampleImpl, my_example_impl, MY_TYPE_EXAMPLE);
* g_io_extension_point_implement ("my-extension-point",
* my_example_impl_get_type (),
* "my-example",
* 10);
* ]|
*
* It is up to the code that registered the extension point how
* it uses the implementations that have been associated with it.
* Depending on the use case, it may use all implementations, or
* only the one with the highest priority, or pick a specific
* one by name.
*
* To avoid opening all modules just to find out what extension
* points they implement, GIO makes use of a caching mechanism,
* see <link linkend="gio-querymodules">gio-querymodules</link>.
* You are expected to run this command after installing a
* GIO module.
*/
struct _GIOModule {
GTypeModule parent_instance;
gchar *filename;
GModule *library;
gboolean initialized; /* The module was loaded at least once */
void (* load) (GIOModule *module);
void (* unload) (GIOModule *module);
};
struct _GIOModuleClass
{
GTypeModuleClass parent_class;
};
static void g_io_module_finalize (GObject *object);
static gboolean g_io_module_load_module (GTypeModule *gmodule);
static void g_io_module_unload_module (GTypeModule *gmodule);
struct _GIOExtension {
char *name;
GType type;
gint priority;
};
struct _GIOExtensionPoint {
GType required_type;
char *name;
GList *extensions;
GList *lazy_load_modules;
};
static GHashTable *extension_points = NULL;
G_LOCK_DEFINE_STATIC(extension_points);
G_DEFINE_TYPE (GIOModule, g_io_module, G_TYPE_TYPE_MODULE);
static void
g_io_module_class_init (GIOModuleClass *class)
{
GObjectClass *object_class = G_OBJECT_CLASS (class);
GTypeModuleClass *type_module_class = G_TYPE_MODULE_CLASS (class);
object_class->finalize = g_io_module_finalize;
type_module_class->load = g_io_module_load_module;
type_module_class->unload = g_io_module_unload_module;
}
static void
g_io_module_init (GIOModule *module)
{
}
static void
g_io_module_finalize (GObject *object)
{
GIOModule *module = G_IO_MODULE (object);
g_free (module->filename);
G_OBJECT_CLASS (g_io_module_parent_class)->finalize (object);
}
static gboolean
g_io_module_load_module (GTypeModule *gmodule)
{
GIOModule *module = G_IO_MODULE (gmodule);
if (!module->filename)
{
g_warning ("GIOModule path not set");
return FALSE;
}
module->library = g_module_open (module->filename, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
if (!module->library)
{
g_printerr ("%s\n", g_module_error ());
return FALSE;
}
/* Make sure that the loaded library contains the required methods */
if (! g_module_symbol (module->library,
"g_io_module_load",
(gpointer) &module->load) ||
! g_module_symbol (module->library,
"g_io_module_unload",
(gpointer) &module->unload))
{
g_printerr ("%s\n", g_module_error ());
g_module_close (module->library);
return FALSE;
}
/* Initialize the loaded module */
module->load (module);
module->initialized = TRUE;
return TRUE;
}
static void
g_io_module_unload_module (GTypeModule *gmodule)
{
GIOModule *module = G_IO_MODULE (gmodule);
module->unload (module);
g_module_close (module->library);
module->library = NULL;
module->load = NULL;
module->unload = NULL;
}
/**
* g_io_module_new:
* @filename: filename of the shared library module.
*
* Creates a new GIOModule that will load the specific
* shared library when in use.
*
* Returns: a #GIOModule from given @filename,
* or %NULL on error.
**/
GIOModule *
g_io_module_new (const gchar *filename)
{
GIOModule *module;
g_return_val_if_fail (filename != NULL, NULL);
module = g_object_new (G_IO_TYPE_MODULE, NULL);
module->filename = g_strdup (filename);
return module;
}
static gboolean
is_valid_module_name (const gchar *basename)
{
#if !defined(G_OS_WIN32) && !defined(G_WITH_CYGWIN)
return
g_str_has_prefix (basename, "lib") &&
g_str_has_suffix (basename, ".so");
#else
return g_str_has_suffix (basename, ".dll");
#endif
}
/**
* g_io_modules_scan_all_in_directory:
* @dirname: pathname for a directory containing modules to scan.
*
* Scans all the modules in the specified directory, ensuring that
* any extension point implemented by a module is registered.
*
* This may not actually load and initialize all the types in each
* module, some modules may be lazily loaded and initialized when
* an extension point it implementes is used with e.g.
* g_io_extension_point_get_extensions() or
* g_io_extension_point_get_extension_by_name().
*
* If you need to guarantee that all types are loaded in all the modules,
* use g_io_modules_load_all_in_directory().
*
* Since: 2.24
**/
void
g_io_modules_scan_all_in_directory (const char *dirname)
{
const gchar *name;
char *filename;
GDir *dir;
GStatBuf statbuf;
char *data;
time_t cache_mtime;
GHashTable *cache;
if (!g_module_supported ())
return;
dir = g_dir_open (dirname, 0, NULL);
if (!dir)
return;
filename = g_build_filename (dirname, "giomodule.cache", NULL);
cache = g_hash_table_new_full (g_str_hash, g_str_equal,
g_free, (GDestroyNotify)g_strfreev);
cache_mtime = 0;
if (g_stat (filename, &statbuf) == 0 &&
g_file_get_contents (filename, &data, NULL, NULL))
{
char **lines;
int i;
/* Cache mtime is the time the cache file was created, any file
* that has a ctime before this was created then and not modified
* since then (userspace can't change ctime). Its possible to change
* the ctime forward without changing the file content, by e.g.
* chmoding the file, but this is uncommon and will only cause us
* to not use the cache so will not cause bugs.
*/
cache_mtime = statbuf.st_mtime;
lines = g_strsplit (data, "\n", -1);
g_free (data);
for (i = 0; lines[i] != NULL; i++)
{
char *line = lines[i];
char *file;
char *colon;
char **extension_points;
if (line[0] == '#')
continue;
colon = strchr (line, ':');
if (colon == NULL || line == colon)
continue; /* Invalid line, ignore */
*colon = 0; /* terminate filename */
file = g_strdup (line);
colon++; /* after colon */
while (g_ascii_isspace (*colon))
colon++;
extension_points = g_strsplit (colon, ",", -1);
g_hash_table_insert (cache, file, extension_points);
}
g_strfreev (lines);
}
while ((name = g_dir_read_name (dir)))
{
if (is_valid_module_name (name))
{
GIOExtensionPoint *extension_point;
GIOModule *module;
gchar *path;
char **extension_points;
int i;
path = g_build_filename (dirname, name, NULL);
module = g_io_module_new (path);
extension_points = g_hash_table_lookup (cache, name);
if (extension_points != NULL &&
g_stat (path, &statbuf) == 0 &&
statbuf.st_ctime <= cache_mtime)
{
/* Lazy load/init the library when first required */
for (i = 0; extension_points[i] != NULL; i++)
{
extension_point =
g_io_extension_point_register (extension_points[i]);
extension_point->lazy_load_modules =
g_list_prepend (extension_point->lazy_load_modules,
module);
}
}
else
{
/* Try to load and init types */
if (g_type_module_use (G_TYPE_MODULE (module)))
g_type_module_unuse (G_TYPE_MODULE (module)); /* Unload */
else
{ /* Failure to load */
g_printerr ("Failed to load module: %s\n", path);
g_object_unref (module);
g_free (path);
continue;
}
}
g_free (path);
}
}
g_dir_close (dir);
g_hash_table_destroy (cache);
g_free (filename);
}
/**
* g_io_modules_load_all_in_directory:
* @dirname: pathname for a directory containing modules to load.
*
* Loads all the modules in the specified directory.
*
* If don't require all modules to be initialized (and thus registering
* all gtypes) then you can use g_io_modules_scan_all_in_directory()
* which allows delayed/lazy loading of modules.
*
* Returns: (element-type GIOModule) (transfer full): a list of #GIOModules loaded
* from the directory,
* All the modules are loaded into memory, if you want to
* unload them (enabling on-demand loading) you must call
* g_type_module_unuse() on all the modules. Free the list
* with g_list_free().
**/
GList *
g_io_modules_load_all_in_directory (const char *dirname)
{
const gchar *name;
GDir *dir;
GList *modules;
if (!g_module_supported ())
return NULL;
dir = g_dir_open (dirname, 0, NULL);
if (!dir)
return NULL;
modules = NULL;
while ((name = g_dir_read_name (dir)))
{
if (is_valid_module_name (name))
{
GIOModule *module;
gchar *path;
path = g_build_filename (dirname, name, NULL);
module = g_io_module_new (path);
if (!g_type_module_use (G_TYPE_MODULE (module)))
{
g_printerr ("Failed to load module: %s\n", path);
g_object_unref (module);
g_free (path);
continue;
}
g_free (path);
modules = g_list_prepend (modules, module);
}
}
g_dir_close (dir);
return modules;
}
G_LOCK_DEFINE_STATIC (registered_extensions);
G_LOCK_DEFINE_STATIC (loaded_dirs);
extern GType _g_fen_directory_monitor_get_type (void);
extern GType _g_fen_file_monitor_get_type (void);
extern GType _g_inotify_directory_monitor_get_type (void);
extern GType _g_inotify_file_monitor_get_type (void);
extern GType _g_unix_volume_monitor_get_type (void);
extern GType _g_local_vfs_get_type (void);
extern GType _g_win32_volume_monitor_get_type (void);
extern GType g_win32_directory_monitor_get_type (void);
extern GType _g_winhttp_vfs_get_type (void);
extern GType _g_dummy_proxy_resolver_get_type (void);
extern GType _g_dummy_tls_backend_get_type (void);
#ifdef G_PLATFORM_WIN32
#include <windows.h>
static HMODULE gio_dll = NULL;
#ifdef DLL_EXPORT
BOOL WINAPI
DllMain (HINSTANCE hinstDLL,
DWORD fdwReason,
LPVOID lpvReserved)
{
if (fdwReason == DLL_PROCESS_ATTACH)
gio_dll = hinstDLL;
return TRUE;
}
#endif
#undef GIO_MODULE_DIR
/* GIO_MODULE_DIR is used only in code called just once,
* so no problem leaking this
*/
#define GIO_MODULE_DIR \
g_build_filename (g_win32_get_package_installation_directory_of_module (gio_dll), \
"lib/gio/modules", \
NULL)
#endif
void
_g_io_modules_ensure_extension_points_registered (void)
{
static gboolean registered_extensions = FALSE;
GIOExtensionPoint *ep;
G_LOCK (registered_extensions);
if (!registered_extensions)
{
registered_extensions = TRUE;
#ifdef G_OS_UNIX
#if !GLIB_CHECK_VERSION (3, 0, 0)
ep = g_io_extension_point_register (G_DESKTOP_APP_INFO_LOOKUP_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_DESKTOP_APP_INFO_LOOKUP);
#endif
#endif
ep = g_io_extension_point_register (G_LOCAL_DIRECTORY_MONITOR_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_LOCAL_DIRECTORY_MONITOR);
ep = g_io_extension_point_register (G_LOCAL_FILE_MONITOR_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_LOCAL_FILE_MONITOR);
ep = g_io_extension_point_register (G_VOLUME_MONITOR_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_VOLUME_MONITOR);
ep = g_io_extension_point_register (G_NATIVE_VOLUME_MONITOR_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_NATIVE_VOLUME_MONITOR);
ep = g_io_extension_point_register (G_VFS_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_VFS);
ep = g_io_extension_point_register ("gsettings-backend");
g_io_extension_point_set_required_type (ep, G_TYPE_OBJECT);
ep = g_io_extension_point_register (G_PROXY_RESOLVER_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_PROXY_RESOLVER);
ep = g_io_extension_point_register (G_PROXY_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_PROXY);
ep = g_io_extension_point_register (G_TLS_BACKEND_EXTENSION_POINT_NAME);
g_io_extension_point_set_required_type (ep, G_TYPE_TLS_BACKEND);
}
G_UNLOCK (registered_extensions);
}
void
_g_io_modules_ensure_loaded (void)
{
static gboolean loaded_dirs = FALSE;
const char *module_path;
_g_io_modules_ensure_extension_points_registered ();
G_LOCK (loaded_dirs);
if (!loaded_dirs)
{
loaded_dirs = TRUE;
g_io_modules_scan_all_in_directory (GIO_MODULE_DIR);
module_path = g_getenv ("GIO_EXTRA_MODULES");
if (module_path)
{
gchar **paths;
int i;
paths = g_strsplit (module_path, ":", 0);
for (i = 0; paths[i] != NULL; i++)
g_io_modules_scan_all_in_directory (paths[i]);
g_strfreev (paths);
}
/* Initialize types from built-in "modules" */
g_null_settings_backend_get_type ();
g_memory_settings_backend_get_type ();
#if defined(HAVE_SYS_INOTIFY_H) || defined(HAVE_LINUX_INOTIFY_H)
_g_inotify_directory_monitor_get_type ();
_g_inotify_file_monitor_get_type ();
#endif
#if defined(HAVE_FEN)
_g_fen_directory_monitor_get_type ();
_g_fen_file_monitor_get_type ();
#endif
#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 ();
#endif
#ifdef G_OS_WIN32
_g_winhttp_vfs_get_type ();
#endif
_g_local_vfs_get_type ();
_g_dummy_proxy_resolver_get_type ();
_g_socks4a_proxy_get_type ();
_g_socks4_proxy_get_type ();
_g_socks5_proxy_get_type ();
_g_dummy_tls_backend_get_type ();
}
G_UNLOCK (loaded_dirs);
}
static void
g_io_extension_point_free (GIOExtensionPoint *ep)
{
g_free (ep->name);
g_free (ep);
}
/**
* g_io_extension_point_register:
* @name: The name of the extension point
*
* Registers an extension point.
*
* Returns: the new #GIOExtensionPoint. This object is owned by GIO
* and should not be freed
*/
GIOExtensionPoint *
g_io_extension_point_register (const char *name)
{
GIOExtensionPoint *ep;
G_LOCK (extension_points);
if (extension_points == NULL)
extension_points = g_hash_table_new_full (g_str_hash,
g_str_equal,
NULL,
(GDestroyNotify)g_io_extension_point_free);
ep = g_hash_table_lookup (extension_points, name);
if (ep != NULL)
{
G_UNLOCK (extension_points);
return ep;
}
ep = g_new0 (GIOExtensionPoint, 1);
ep->name = g_strdup (name);
g_hash_table_insert (extension_points, ep->name, ep);
G_UNLOCK (extension_points);
return ep;
}
/**
* g_io_extension_point_lookup:
* @name: the name of the extension point
*
* Looks up an existing extension point.
*
* Returns: the #GIOExtensionPoint, or %NULL if there is no
* registered extension point with the given name
*/
GIOExtensionPoint *
g_io_extension_point_lookup (const char *name)
{
GIOExtensionPoint *ep;
G_LOCK (extension_points);
ep = NULL;
if (extension_points != NULL)
ep = g_hash_table_lookup (extension_points, name);
G_UNLOCK (extension_points);
return ep;
}
/**
* g_io_extension_point_set_required_type:
* @extension_point: a #GIOExtensionPoint
* @type: the #GType to require
*
* Sets the required type for @extension_point to @type.
* All implementations must henceforth have this type.
*/
void
g_io_extension_point_set_required_type (GIOExtensionPoint *extension_point,
GType type)
{
extension_point->required_type = type;
}
/**
* g_io_extension_point_get_required_type:
* @extension_point: a #GIOExtensionPoint
*
* Gets the required type for @extension_point.
*
* Returns: the #GType that all implementations must have,
* or #G_TYPE_INVALID if the extension point has no required type
*/
GType
g_io_extension_point_get_required_type (GIOExtensionPoint *extension_point)
{
return extension_point->required_type;
}
void
lazy_load_modules (GIOExtensionPoint *extension_point)
{
GIOModule *module;
GList *l;
for (l = extension_point->lazy_load_modules; l != NULL; l = l->next)
{
module = l->data;
if (!module->initialized)
{
if (g_type_module_use (G_TYPE_MODULE (module)))
g_type_module_unuse (G_TYPE_MODULE (module)); /* Unload */
else
g_printerr ("Failed to load module: %s\n",
module->filename);
}
}
}
/**
* g_io_extension_point_get_extensions:
* @extension_point: a #GIOExtensionPoint
*
* Gets a list of all extensions that implement this extension point.
* The list is sorted by priority, beginning with the highest priority.
*
* Returns: (element-type GIOExtension) (transfer none): a #GList of
* #GIOExtension<!-- -->s. The list is owned by GIO and should not be
* modified.
*/
GList *
g_io_extension_point_get_extensions (GIOExtensionPoint *extension_point)
{
lazy_load_modules (extension_point);
return extension_point->extensions;
}
/**
* g_io_extension_point_get_extension_by_name:
* @extension_point: a #GIOExtensionPoint
* @name: the name of the extension to get
*
* Finds a #GIOExtension for an extension point by name.
*
* Returns: (transfer none): the #GIOExtension for @extension_point that has the
* given name, or %NULL if there is no extension with that name
*/
GIOExtension *
g_io_extension_point_get_extension_by_name (GIOExtensionPoint *extension_point,
const char *name)
{
GList *l;
lazy_load_modules (extension_point);
for (l = extension_point->extensions; l != NULL; l = l->next)
{
GIOExtension *e = l->data;
if (e->name != NULL &&
strcmp (e->name, name) == 0)
return e;
}
return NULL;
}
static gint
extension_prio_compare (gconstpointer a,
gconstpointer b)
{
const GIOExtension *extension_a = a, *extension_b = b;
if (extension_a->priority > extension_b->priority)
return -1;
if (extension_b->priority > extension_a->priority)
return 1;
return 0;
}
/**
* g_io_extension_point_implement:
* @extension_point_name: the name of the extension point
* @type: the #GType to register as extension
* @extension_name: the name for the extension
* @priority: the priority for the extension
*
* Registers @type as extension for the extension point with name
* @extension_point_name.
*
* If @type has already been registered as an extension for this
* extension point, the existing #GIOExtension object is returned.
*
* Returns: a #GIOExtension object for #GType
*/
GIOExtension *
g_io_extension_point_implement (const char *extension_point_name,
GType type,
const char *extension_name,
gint priority)
{
GIOExtensionPoint *extension_point;
GIOExtension *extension;
GList *l;
g_return_val_if_fail (extension_point_name != NULL, NULL);
extension_point = g_io_extension_point_lookup (extension_point_name);
if (extension_point == NULL)
{
g_warning ("Tried to implement non-registered extension point %s", extension_point_name);
return NULL;
}
if (extension_point->required_type != 0 &&
!g_type_is_a (type, extension_point->required_type))
{
g_warning ("Tried to register an extension of the type %s to extension point %s. "
"Expected type is %s.",
g_type_name (type),
extension_point_name,
g_type_name (extension_point->required_type));
return NULL;
}
/* It's safe to register the same type multiple times */
for (l = extension_point->extensions; l != NULL; l = l->next)
{
extension = l->data;
if (extension->type == type)
return extension;
}
extension = g_slice_new0 (GIOExtension);
extension->type = type;
extension->name = g_strdup (extension_name);
extension->priority = priority;
extension_point->extensions = g_list_insert_sorted (extension_point->extensions,
extension, extension_prio_compare);
return extension;
}
/**
* g_io_extension_ref_class:
* @extension: a #GIOExtension
*
* Gets a reference to the class for the type that is
* associated with @extension.
*
* Returns: (transfer full): the #GTypeClass for the type of @extension
*/
GTypeClass *
g_io_extension_ref_class (GIOExtension *extension)
{
return g_type_class_ref (extension->type);
}
/**
* g_io_extension_get_type:
* @extension: a #GIOExtension
*
* Gets the type associated with @extension.
*
* Returns: the type of @extension
*/
GType
g_io_extension_get_type (GIOExtension *extension)
{
return extension->type;
}
/**
* g_io_extension_get_name:
* @extension: a #GIOExtension
*
* Gets the name under which @extension was registered.
*
* Note that the same type may be registered as extension
* for multiple extension points, under different names.
*
* Returns: the name of @extension.
*/
const char *
g_io_extension_get_name (GIOExtension *extension)
{
return extension->name;
}
/**
* g_io_extension_get_priority:
* @extension: a #GIOExtension
*
* Gets the priority with which @extension was registered.
*
* Returns: the priority of @extension
*/
gint
g_io_extension_get_priority (GIOExtension *extension)
{
return extension->priority;
}
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