1 /* GIO - GLib Input, Output and Streaming Library
2 *
3 * Copyright (C) 2006-2007 Red Hat, Inc.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General
16 * Public License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
18 * Boston, MA 02111-1307, USA.
19 *
20 * Author: Alexander Larsson <alexl@redhat.com>
21 */
22
23 #include "config.h"
24
25 #include <string.h>
26
27 #include "giomodule.h"
28 #include "giomodule-priv.h"
29 #include "glocalfilemonitor.h"
30 #include "glocaldirectorymonitor.h"
31 #include "gnativevolumemonitor.h"
32 #include "gvfs.h"
33 #ifdef G_OS_UNIX
34 #include "gdesktopappinfo.h"
35 #endif
36 #include "gioalias.h"
37
38 /**
39 * SECTION:giomodule
40 * @short_description: Loadable GIO Modules
41 * @include: gio/gio.h
42 *
43 * Provides an interface and default functions for loading and unloading
44 * modules. This is used internally to make GIO extensible, but can also
45 * be used by others to implement module loading.
46 *
47 **/
48
49 /**
50 * SECTION:extensionpoints
51 * @short_description: Extension Points
52 * @include: gio.h
53 * @see_also: <link linkend="extending-gio">Extending GIO</link>
54 *
55 * #GIOExtensionPoint provides a mechanism for modules to extend the
56 * functionality of the library or application that loaded it in an
57 * organized fashion.
58 *
59 * An extension point is identified by a name, and it may optionally
60 * require that any implementation must by of a certain type (or derived
61 * thereof). Use g_io_extension_point_register() to register an
62 * extension point, and g_io_extension_point_set_required_type() to
63 * set a required type.
64 *
65 * A module can implement an extension point by specifying the #GType
66 * that implements the functionality. Additionally, each implementation
67 * of an extension point has a name, and a priority. Use
68 * g_io_extension_point_implement() to implement an extension point.
69 *
70 * |[
71 * GIOExtensionPoint *ep;
72 *
73 * /* Register an extension point */
74 * ep = g_io_extension_point_register ("my-extension-point");
75 * g_io_extension_point_set_required_type (ep, MY_TYPE_EXAMPLE);
76 * ]|
77 *
78 * |[
79 * /* Implement an extension point */
80 * G_DEFINE_TYPE (MyExampleImpl, my_example_impl, MY_TYPE_EXAMPLE);
81 * g_io_extension_point_implement ("my-extension-point",
82 * my_example_impl_get_type (),
83 * "my-example",
84 * 10);
85 * ]|
86 *
87 * It is up to the code that registered the extension point how
88 * it uses the implementations that have been associated with it.
89 * Depending on the use case, it may use all implementations, or
90 * only the one with the highest priority, or pick a specific
91 * one by name.
92 */
93 struct _GIOModule {
94 GTypeModule parent_instance;
95
96 gchar *filename;
97 GModule *library;
98
99 void (* load) (GIOModule *module);
100 void (* unload) (GIOModule *module);
101 };
102
103 struct _GIOModuleClass
104 {
105 GTypeModuleClass parent_class;
106
107 };
108
109 static void g_io_module_finalize (GObject *object);
110 static gboolean g_io_module_load_module (GTypeModule *gmodule);
111 static void g_io_module_unload_module (GTypeModule *gmodule);
112
113 G_DEFINE_TYPE (GIOModule, g_io_module, G_TYPE_TYPE_MODULE);
114
115 static void
g_io_module_class_init(GIOModuleClass * class)116 g_io_module_class_init (GIOModuleClass *class)
117 {
118 GObjectClass *object_class = G_OBJECT_CLASS (class);
119 GTypeModuleClass *type_module_class = G_TYPE_MODULE_CLASS (class);
120
121 object_class->finalize = g_io_module_finalize;
122
123 type_module_class->load = g_io_module_load_module;
124 type_module_class->unload = g_io_module_unload_module;
125 }
126
127 static void
g_io_module_init(GIOModule * module)128 g_io_module_init (GIOModule *module)
129 {
130 }
131
132 static void
g_io_module_finalize(GObject * object)133 g_io_module_finalize (GObject *object)
134 {
135 GIOModule *module = G_IO_MODULE (object);
136
137 g_free (module->filename);
138
139 G_OBJECT_CLASS (g_io_module_parent_class)->finalize (object);
140 }
141
142 static gboolean
g_io_module_load_module(GTypeModule * gmodule)143 g_io_module_load_module (GTypeModule *gmodule)
144 {
145 GIOModule *module = G_IO_MODULE (gmodule);
146
147 if (!module->filename)
148 {
149 g_warning ("GIOModule path not set");
150 return FALSE;
151 }
152
153 module->library = g_module_open (module->filename, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
154
155 if (!module->library)
156 {
157 g_printerr ("%s\n", g_module_error ());
158 return FALSE;
159 }
160
161 /* Make sure that the loaded library contains the required methods */
162 if (! g_module_symbol (module->library,
163 "g_io_module_load",
164 (gpointer) &module->load) ||
165 ! g_module_symbol (module->library,
166 "g_io_module_unload",
167 (gpointer) &module->unload))
168 {
169 g_printerr ("%s\n", g_module_error ());
170 g_module_close (module->library);
171
172 return FALSE;
173 }
174
175 /* Initialize the loaded module */
176 module->load (module);
177
178 return TRUE;
179 }
180
181 static void
g_io_module_unload_module(GTypeModule * gmodule)182 g_io_module_unload_module (GTypeModule *gmodule)
183 {
184 GIOModule *module = G_IO_MODULE (gmodule);
185
186 module->unload (module);
187
188 g_module_close (module->library);
189 module->library = NULL;
190
191 module->load = NULL;
192 module->unload = NULL;
193 }
194
195 /**
196 * g_io_module_new:
197 * @filename: filename of the shared library module.
198 *
199 * Creates a new GIOModule that will load the specific
200 * shared library when in use.
201 *
202 * Returns: a #GIOModule from given @filename,
203 * or %NULL on error.
204 **/
205 GIOModule *
g_io_module_new(const gchar * filename)206 g_io_module_new (const gchar *filename)
207 {
208 GIOModule *module;
209
210 g_return_val_if_fail (filename != NULL, NULL);
211
212 module = g_object_new (G_IO_TYPE_MODULE, NULL);
213 module->filename = g_strdup (filename);
214
215 return module;
216 }
217
218 static gboolean
is_valid_module_name(const gchar * basename)219 is_valid_module_name (const gchar *basename)
220 {
221 #if !defined(G_OS_WIN32) && !defined(G_WITH_CYGWIN)
222 return
223 g_str_has_prefix (basename, "lib") &&
224 g_str_has_suffix (basename, ".so");
225 #else
226 return g_str_has_suffix (basename, ".dll");
227 #endif
228 }
229
230 /**
231 * g_io_modules_load_all_in_directory:
232 * @dirname: pathname for a directory containing modules to load.
233 *
234 * Loads all the modules in the specified directory.
235 *
236 * Returns: a list of #GIOModules loaded from the directory,
237 * All the modules are loaded into memory, if you want to
238 * unload them (enabling on-demand loading) you must call
239 * g_type_module_unuse() on all the modules. Free the list
240 * with g_list_free().
241 **/
242 GList *
g_io_modules_load_all_in_directory(const char * dirname)243 g_io_modules_load_all_in_directory (const char *dirname)
244 {
245 const gchar *name;
246 GDir *dir;
247 GList *modules;
248
249 if (!g_module_supported ())
250 return NULL;
251
252 dir = g_dir_open (dirname, 0, NULL);
253 if (!dir)
254 return NULL;
255
256 modules = NULL;
257 while ((name = g_dir_read_name (dir)))
258 {
259 if (is_valid_module_name (name))
260 {
261 GIOModule *module;
262 gchar *path;
263
264 path = g_build_filename (dirname, name, NULL);
265 module = g_io_module_new (path);
266
267 if (!g_type_module_use (G_TYPE_MODULE (module)))
268 {
269 g_printerr ("Failed to load module: %s\n", path);
270 g_object_unref (module);
271 g_free (path);
272 continue;
273 }
274
275 g_free (path);
276
277 modules = g_list_prepend (modules, module);
278 }
279 }
280
281 g_dir_close (dir);
282
283 return modules;
284 }
285
286 G_LOCK_DEFINE_STATIC (registered_extensions);
287 G_LOCK_DEFINE_STATIC (loaded_dirs);
288
289 extern GType _g_fen_directory_monitor_get_type (void);
290 extern GType _g_fen_file_monitor_get_type (void);
291 extern GType _g_inotify_directory_monitor_get_type (void);
292 extern GType _g_inotify_file_monitor_get_type (void);
293 extern GType _g_unix_volume_monitor_get_type (void);
294 extern GType _g_local_vfs_get_type (void);
295
296 extern GType _g_win32_volume_monitor_get_type (void);
297 extern GType g_win32_directory_monitor_get_type (void);
298 extern GType _g_winhttp_vfs_get_type (void);
299
300 void
_g_io_modules_ensure_extension_points_registered(void)301 _g_io_modules_ensure_extension_points_registered (void)
302 {
303 static gboolean registered_extensions = FALSE;
304 GIOExtensionPoint *ep;
305
306 G_LOCK (registered_extensions);
307
308 if (!registered_extensions)
309 {
310 registered_extensions = TRUE;
311
312 #ifdef G_OS_UNIX
313 ep = g_io_extension_point_register (G_DESKTOP_APP_INFO_LOOKUP_EXTENSION_POINT_NAME);
314 g_io_extension_point_set_required_type (ep, G_TYPE_DESKTOP_APP_INFO_LOOKUP);
315 #endif
316
317 ep = g_io_extension_point_register (G_LOCAL_DIRECTORY_MONITOR_EXTENSION_POINT_NAME);
318 g_io_extension_point_set_required_type (ep, G_TYPE_LOCAL_DIRECTORY_MONITOR);
319
320 ep = g_io_extension_point_register (G_LOCAL_FILE_MONITOR_EXTENSION_POINT_NAME);
321 g_io_extension_point_set_required_type (ep, G_TYPE_LOCAL_FILE_MONITOR);
322
323 ep = g_io_extension_point_register (G_VOLUME_MONITOR_EXTENSION_POINT_NAME);
324 g_io_extension_point_set_required_type (ep, G_TYPE_VOLUME_MONITOR);
325
326 ep = g_io_extension_point_register (G_NATIVE_VOLUME_MONITOR_EXTENSION_POINT_NAME);
327 g_io_extension_point_set_required_type (ep, G_TYPE_NATIVE_VOLUME_MONITOR);
328
329 ep = g_io_extension_point_register (G_VFS_EXTENSION_POINT_NAME);
330 g_io_extension_point_set_required_type (ep, G_TYPE_VFS);
331 }
332
333 G_UNLOCK (registered_extensions);
334 }
335
336 void
_g_io_modules_ensure_loaded(void)337 _g_io_modules_ensure_loaded (void)
338 {
339 GList *modules, *l;
340 static gboolean loaded_dirs = FALSE;
341 const char *module_path;
342
343 _g_io_modules_ensure_extension_points_registered ();
344
345 G_LOCK (loaded_dirs);
346
347 if (!loaded_dirs)
348 {
349 loaded_dirs = TRUE;
350
351 modules = g_io_modules_load_all_in_directory (GIO_MODULE_DIR);
352
353 module_path = g_getenv ("GIO_EXTRA_MODULES");
354
355 if (module_path)
356 {
357 int i = 0;
358 gchar **paths;
359 paths = g_strsplit (module_path, ":", 0);
360
361 while (paths[i] != NULL)
362 {
363 modules = g_list_concat (modules, g_io_modules_load_all_in_directory (paths[i]));
364 i++;
365 }
366
367 g_strfreev (paths);
368 }
369
370 /* Initialize types from built-in "modules" */
371 #if defined(HAVE_SYS_INOTIFY_H) || defined(HAVE_LINUX_INOTIFY_H)
372 _g_inotify_directory_monitor_get_type ();
373 _g_inotify_file_monitor_get_type ();
374 #endif
375 #if defined(HAVE_FEN)
376 _g_fen_directory_monitor_get_type ();
377 _g_fen_file_monitor_get_type ();
378 #endif
379 #ifdef G_OS_WIN32
380 _g_win32_volume_monitor_get_type ();
381 g_win32_directory_monitor_get_type ();
382 #endif
383 #ifdef G_OS_UNIX
384 _g_unix_volume_monitor_get_type ();
385 #endif
386 #ifdef G_OS_WIN32
387 _g_winhttp_vfs_get_type ();
388 #endif
389 _g_local_vfs_get_type ();
390
391 for (l = modules; l != NULL; l = l->next)
392 g_type_module_unuse (G_TYPE_MODULE (l->data));
393
394 g_list_free (modules);
395 }
396
397 G_UNLOCK (loaded_dirs);
398 }
399
400 struct _GIOExtension {
401 char *name;
402 GType type;
403 gint priority;
404 };
405
406 struct _GIOExtensionPoint {
407 GType required_type;
408 char *name;
409 GList *extensions;
410 };
411
412 static GHashTable *extension_points = NULL;
413 G_LOCK_DEFINE_STATIC(extension_points);
414
415
416 static void
g_io_extension_point_free(GIOExtensionPoint * ep)417 g_io_extension_point_free (GIOExtensionPoint *ep)
418 {
419 g_free (ep->name);
420 g_free (ep);
421 }
422
423 /**
424 * g_io_extension_point_register:
425 * @name: The name of the extension point
426 *
427 * Registers an extension point.
428 *
429 * Returns: the new #GIOExtensionPoint. This object is owned by GIO
430 * and should not be freed
431 */
432 GIOExtensionPoint *
g_io_extension_point_register(const char * name)433 g_io_extension_point_register (const char *name)
434 {
435 GIOExtensionPoint *ep;
436
437 G_LOCK (extension_points);
438 if (extension_points == NULL)
439 extension_points = g_hash_table_new_full (g_str_hash,
440 g_str_equal,
441 NULL,
442 (GDestroyNotify)g_io_extension_point_free);
443
444 if (g_hash_table_lookup (extension_points, name) != NULL)
445 {
446 g_warning ("Extension point %s registered multiple times", name);
447 G_UNLOCK (extension_points);
448 return NULL;
449 }
450
451 ep = g_new0 (GIOExtensionPoint, 1);
452 ep->name = g_strdup (name);
453
454 g_hash_table_insert (extension_points, ep->name, ep);
455
456 G_UNLOCK (extension_points);
457
458 return ep;
459 }
460
461 /**
462 * g_io_extension_point_lookup:
463 * @name: the name of the extension point
464 *
465 * Looks up an existing extension point.
466 *
467 * Returns: the #GIOExtensionPoint, or %NULL if there is no
468 * registered extension point with the given name
469 */
470 GIOExtensionPoint *
g_io_extension_point_lookup(const char * name)471 g_io_extension_point_lookup (const char *name)
472 {
473 GIOExtensionPoint *ep;
474
475 G_LOCK (extension_points);
476 ep = NULL;
477 if (extension_points != NULL)
478 ep = g_hash_table_lookup (extension_points, name);
479
480 G_UNLOCK (extension_points);
481
482 return ep;
483
484 }
485
486 /**
487 * g_io_extension_point_set_required_type:
488 * @extension_point: a #GIOExtensionPoint
489 * @type: the #GType to require
490 *
491 * Sets the required type for @extension_point to @type.
492 * All implementations must henceforth have this type.
493 */
494 void
g_io_extension_point_set_required_type(GIOExtensionPoint * extension_point,GType type)495 g_io_extension_point_set_required_type (GIOExtensionPoint *extension_point,
496 GType type)
497 {
498 extension_point->required_type = type;
499 }
500
501 /**
502 * g_io_extension_point_get_required_type:
503 * @extension_point: a #GIOExtensionPoint
504 *
505 * Gets the required type for @extension_point.
506 *
507 * Returns: the #GType that all implementations must have,
508 * or #G_TYPE_INVALID if the extension point has no required type
509 */
510 GType
g_io_extension_point_get_required_type(GIOExtensionPoint * extension_point)511 g_io_extension_point_get_required_type (GIOExtensionPoint *extension_point)
512 {
513 return extension_point->required_type;
514 }
515
516 /**
517 * g_io_extension_point_get_extensions:
518 * @extension_point: a #GIOExtensionPoint
519 *
520 * Gets a list of all extensions that implement this extension point.
521 * The list is sorted by priority, beginning with the highest priority.
522 *
523 * Returns: a #GList of #GIOExtension<!-- -->s. The list is owned by
524 * GIO and should not be modified
525 */
526 GList *
g_io_extension_point_get_extensions(GIOExtensionPoint * extension_point)527 g_io_extension_point_get_extensions (GIOExtensionPoint *extension_point)
528 {
529 return extension_point->extensions;
530 }
531
532 /**
533 * g_io_extension_point_get_extension_by_name:
534 * @extension_point: a #GIOExtensionPoint
535 * @name: the name of the extension to get
536 *
537 * Finds a #GIOExtension for an extension point by name.
538 *
539 * Returns: the #GIOExtension for @extension_point that has the
540 * given name, or %NULL if there is no extension with that name
541 */
542 GIOExtension *
g_io_extension_point_get_extension_by_name(GIOExtensionPoint * extension_point,const char * name)543 g_io_extension_point_get_extension_by_name (GIOExtensionPoint *extension_point,
544 const char *name)
545 {
546 GList *l;
547
548 for (l = extension_point->extensions; l != NULL; l = l->next)
549 {
550 GIOExtension *e = l->data;
551
552 if (e->name != NULL &&
553 strcmp (e->name, name) == 0)
554 return e;
555 }
556
557 return NULL;
558 }
559
560 static gint
extension_prio_compare(gconstpointer a,gconstpointer b)561 extension_prio_compare (gconstpointer a,
562 gconstpointer b)
563 {
564 const GIOExtension *extension_a = a, *extension_b = b;
565
566 return extension_b->priority - extension_a->priority;
567 }
568
569 /**
570 * g_io_extension_point_implement:
571 * @extension_point_name: the name of the extension point
572 * @type: the #GType to register as extension
573 * @extension_name: the name for the extension
574 * @priority: the priority for the extension
575 *
576 * Registers @type as extension for the extension point with name
577 * @extension_point_name.
578 *
579 * If @type has already been registered as an extension for this
580 * extension point, the existing #GIOExtension object is returned.
581 *
582 * Returns: a #GIOExtension object for #GType
583 */
584 GIOExtension *
g_io_extension_point_implement(const char * extension_point_name,GType type,const char * extension_name,gint priority)585 g_io_extension_point_implement (const char *extension_point_name,
586 GType type,
587 const char *extension_name,
588 gint priority)
589 {
590 GIOExtensionPoint *extension_point;
591 GIOExtension *extension;
592 GList *l;
593
594 g_return_val_if_fail (extension_point_name != NULL, NULL);
595
596 extension_point = g_io_extension_point_lookup (extension_point_name);
597 if (extension_point == NULL)
598 {
599 g_warning ("Tried to implement non-registered extension point %s", extension_point_name);
600 return NULL;
601 }
602
603 if (extension_point->required_type != 0 &&
604 !g_type_is_a (type, extension_point->required_type))
605 {
606 g_warning ("Tried to register an extension of the type %s to extension point %s. "
607 "Expected type is %s.",
608 g_type_name (type),
609 extension_point_name,
610 g_type_name (extension_point->required_type));
611 return NULL;
612 }
613
614 /* It's safe to register the same type multiple times */
615 for (l = extension_point->extensions; l != NULL; l = l->next)
616 {
617 extension = l->data;
618 if (extension->type == type)
619 return extension;
620 }
621
622 extension = g_slice_new0 (GIOExtension);
623 extension->type = type;
624 extension->name = g_strdup (extension_name);
625 extension->priority = priority;
626
627 extension_point->extensions = g_list_insert_sorted (extension_point->extensions,
628 extension, extension_prio_compare);
629
630 return extension;
631 }
632
633 /**
634 * g_io_extension_ref_class:
635 * @extension: a #GIOExtension
636 *
637 * Gets a reference to the class for the type that is
638 * associated with @extension.
639 *
640 * Returns: the #GTypeClass for the type of @extension
641 */
642 GTypeClass *
g_io_extension_ref_class(GIOExtension * extension)643 g_io_extension_ref_class (GIOExtension *extension)
644 {
645 return g_type_class_ref (extension->type);
646 }
647
648 /**
649 * g_io_extension_get_type:
650 * @extension: a #GIOExtension
651 *
652 * Gets the type associated with @extension.
653 *
654 * Returns: the type of @extension
655 */
656 GType
g_io_extension_get_type(GIOExtension * extension)657 g_io_extension_get_type (GIOExtension *extension)
658 {
659 return extension->type;
660 }
661
662 /**
663 * g_io_extension_get_name:
664 * @extension: a #GIOExtension
665 *
666 * Gets the name under which @extension was registered.
667 *
668 * Note that the same type may be registered as extension
669 * for multiple extension points, under different names.
670 *
671 * Returns: the name of @extension.
672 */
673 const char *
g_io_extension_get_name(GIOExtension * extension)674 g_io_extension_get_name (GIOExtension *extension)
675 {
676 return extension->name;
677 }
678
679 /**
680 * g_io_extension_get_priority:
681 * @extension: a #GIOExtension
682 *
683 * Gets the priority with which @extension was registered.
684 *
685 * Returns: the priority of @extension
686 */
687 gint
g_io_extension_get_priority(GIOExtension * extension)688 g_io_extension_get_priority (GIOExtension *extension)
689 {
690 return extension->priority;
691 }
692
693 #define __G_IO_MODULE_C__
694 #include "gioaliasdef.c"
695