gio/gvfs.c - third_party/glib - Git at Google

 /* GIO - GLib Input, Output and Streaming Library
  *
  * Copyright (C) 2006-2007 Red Hat, Inc.
  *
  * SPDX-License-Identifier: LGPL-2.1-or-later
  *
  * 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 2.1 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, see <http://www.gnu.org/licenses/>.
  *
  * Author: Alexander Larsson <alexl@redhat.com>
  */

 #include "config.h"
 #include <string.h>
 #include "gvfs.h"
 #include "glib-private.h"
 #include "glocalvfs.h"
 #include "gresourcefile.h"
 #include "giomodule-priv.h"
 #include "glibintl.h"


 /**
  * GVfs:
  *
  * Entry point for using GIO functionality.
  */

 static GRWLock additional_schemes_lock;

 typedef struct _GVfsPrivate {
   GHashTable *additional_schemes;
   char const **supported_schemes;
 } GVfsPrivate;

 typedef struct {
   GVfsFileLookupFunc uri_func;
   gpointer uri_data;
   GDestroyNotify uri_destroy;

   GVfsFileLookupFunc parse_name_func;
   gpointer parse_name_data;
   GDestroyNotify parse_name_destroy;
 } GVfsURISchemeData;

 G_DEFINE_TYPE_WITH_PRIVATE (GVfs, g_vfs, G_TYPE_OBJECT)

 static void
 g_vfs_dispose (GObject *object)
 {
   GVfs *vfs = G_VFS (object);
   GVfsPrivate *priv = g_vfs_get_instance_private (vfs);

   g_clear_pointer (&priv->additional_schemes, g_hash_table_destroy);
   g_clear_pointer (&priv->supported_schemes, g_free);

   G_OBJECT_CLASS (g_vfs_parent_class)->dispose (object);
 }

 static void
 g_vfs_class_init (GVfsClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   object_class->dispose = g_vfs_dispose;
 }

 static GFile *
 resource_parse_name (GVfs       *vfs,
                      const char *parse_name,
                      gpointer    user_data)
 {
   if (g_str_has_prefix (parse_name, "resource:"))
     return _g_resource_file_new (parse_name);

   return NULL;
 }

 static GFile *
 resource_get_file_for_uri (GVfs       *vfs,
                            const char *uri,
                            gpointer    user_data)
 {
   return _g_resource_file_new (uri);
 }

 static void
 g_vfs_uri_lookup_func_closure_free (gpointer data)
 {
   GVfsURISchemeData *closure = data;

   if (closure->uri_destroy)
     closure->uri_destroy (closure->uri_data);
   if (closure->parse_name_destroy)
     closure->parse_name_destroy (closure->parse_name_data);

   g_free (closure);
 }

 static void
 g_vfs_init (GVfs *vfs)
 {
   GVfsPrivate *priv = g_vfs_get_instance_private (vfs);
   priv->additional_schemes =
     g_hash_table_new_full (g_str_hash, g_str_equal,
                            g_free, g_vfs_uri_lookup_func_closure_free);

   g_vfs_register_uri_scheme (vfs, "resource",
                              resource_get_file_for_uri, NULL, NULL,
                              resource_parse_name, NULL, NULL);
 }

 /**
  * g_vfs_is_active:
  * @vfs: a #GVfs.
  *
  * Checks if the VFS is active.
  *
  * Returns: %TRUE if construction of the @vfs was successful
  *     and it is now active.
  */
 gboolean
 g_vfs_is_active (GVfs *vfs)
 {
   GVfsClass *class;

   g_return_val_if_fail (G_IS_VFS (vfs), FALSE);

   class = G_VFS_GET_CLASS (vfs);

   return (* class->is_active) (vfs);
 }


 /**
  * g_vfs_get_file_for_path:
  * @vfs: a #GVfs.
  * @path: a string containing a VFS path.
  *
  * Gets a #GFile for @path.
  *
  * Returns: (transfer full): a #GFile.
  *     Free the returned object with g_object_unref().
  */
 GFile *
 g_vfs_get_file_for_path (GVfs       *vfs,
                          const char *path)
 {
   GVfsClass *class;

   g_return_val_if_fail (G_IS_VFS (vfs), NULL);
   g_return_val_if_fail (path != NULL, NULL);

   class = G_VFS_GET_CLASS (vfs);

   return (* class->get_file_for_path) (vfs, path);
 }

 static GFile *
 parse_name_internal (GVfs       *vfs,
                      const char *parse_name)
 {
   GVfsPrivate *priv = g_vfs_get_instance_private (vfs);
   GHashTableIter iter;
   GVfsURISchemeData *closure;
   GFile *ret = NULL;

   g_rw_lock_reader_lock (&additional_schemes_lock);
   g_hash_table_iter_init (&iter, priv->additional_schemes);

   while (g_hash_table_iter_next (&iter, NULL, (gpointer *) &closure))
     {
       ret = closure->parse_name_func (vfs, parse_name,
                                       closure->parse_name_data);

       if (ret)
         break;
     }

   g_rw_lock_reader_unlock (&additional_schemes_lock);

   return ret;
 }

 static GFile *
 get_file_for_uri_internal (GVfs       *vfs,
                            const char *uri)
 {
   GVfsPrivate *priv = g_vfs_get_instance_private (vfs);
   GFile *ret = NULL;
   char *scheme;
   GVfsURISchemeData *closure;

   scheme = g_uri_parse_scheme (uri);
   if (scheme == NULL)
     return NULL;

   g_rw_lock_reader_lock (&additional_schemes_lock);
   closure = g_hash_table_lookup (priv->additional_schemes, scheme);

   if (closure)
     ret = closure->uri_func (vfs, uri, closure->uri_data);

   g_rw_lock_reader_unlock (&additional_schemes_lock);

   g_free (scheme);
   return ret;
 }

 /**
  * g_vfs_get_file_for_uri:
  * @vfs: a#GVfs.
  * @uri: a string containing a URI
  *
  * Gets a #GFile for @uri.
  *
  * This operation never fails, but the returned object
  * might not support any I/O operation if the URI
  * is malformed or if the URI scheme is not supported.
  *
  * Returns: (transfer full): a #GFile.
  *     Free the returned object with g_object_unref().
  */
 GFile *
 g_vfs_get_file_for_uri (GVfs       *vfs,
                         const char *uri)
 {
   GVfsClass *class;
   GFile *ret = NULL;

   g_return_val_if_fail (G_IS_VFS (vfs), NULL);
   g_return_val_if_fail (uri != NULL, NULL);

   class = G_VFS_GET_CLASS (vfs);

   ret = get_file_for_uri_internal (vfs, uri);
   if (!ret)
     ret = (* class->get_file_for_uri) (vfs, uri);

   g_assert (ret != NULL);

   return g_steal_pointer (&ret);
 }

 /**
  * g_vfs_get_supported_uri_schemes:
  * @vfs: a #GVfs.
  *
  * Gets a list of URI schemes supported by @vfs.
  *
  * Returns: (transfer none): a %NULL-terminated array of strings.
  *     The returned array belongs to GIO and must
  *     not be freed or modified.
  */
 const gchar * const *
 g_vfs_get_supported_uri_schemes (GVfs *vfs)
 {
   GVfsPrivate *priv;

   g_return_val_if_fail (G_IS_VFS (vfs), NULL);

   priv = g_vfs_get_instance_private (vfs);

   if (!priv->supported_schemes)
     {
       GVfsClass *class;
       const char * const *default_schemes;
       const char *additional_scheme;
       GPtrArray *supported_schemes;
       GHashTableIter iter;

       class = G_VFS_GET_CLASS (vfs);

       default_schemes = (* class->get_supported_uri_schemes) (vfs);
       supported_schemes = g_ptr_array_new ();

       for (; default_schemes && *default_schemes; default_schemes++)
         g_ptr_array_add (supported_schemes, (gpointer) *default_schemes);

       g_rw_lock_reader_lock (&additional_schemes_lock);
       g_hash_table_iter_init (&iter, priv->additional_schemes);

       while (g_hash_table_iter_next
              (&iter, (gpointer *) &additional_scheme, NULL))
         g_ptr_array_add (supported_schemes, (gpointer) additional_scheme);

       g_rw_lock_reader_unlock (&additional_schemes_lock);

       g_ptr_array_add (supported_schemes, NULL);

       g_free (priv->supported_schemes);
       priv->supported_schemes =
         (char const **) g_ptr_array_free (supported_schemes, FALSE);
     }

   return priv->supported_schemes;
 }

 /**
  * g_vfs_parse_name:
  * @vfs: a #GVfs.
  * @parse_name: a string to be parsed by the VFS module.
  *
  * This operation never fails, but the returned object might
  * not support any I/O operations if the @parse_name cannot
  * be parsed by the #GVfs module.
  *
  * Returns: (transfer full): a #GFile for the given @parse_name.
  *     Free the returned object with g_object_unref().
  */
 GFile *
 g_vfs_parse_name (GVfs       *vfs,
                   const char *parse_name)
 {
   GVfsClass *class;
   GFile *ret;

   g_return_val_if_fail (G_IS_VFS (vfs), NULL);
   g_return_val_if_fail (parse_name != NULL, NULL);

   class = G_VFS_GET_CLASS (vfs);

   ret = parse_name_internal (vfs, parse_name);
   if (ret)
     return ret;

   return (* class->parse_name) (vfs, parse_name);
 }

 static GVfs *vfs_default_singleton = NULL;  /* (owned) (atomic) */

 /**
  * g_vfs_get_default:
  *
  * Gets the default #GVfs for the system.
  *
  * Returns: (not nullable) (transfer none): a #GVfs, which will be the local
  *     file system #GVfs if no other implementation is available.
  */
 GVfs *
 g_vfs_get_default (void)
 {
   if (GLIB_PRIVATE_CALL (g_check_setuid) ())
     return g_vfs_get_local ();

   if (g_once_init_enter_pointer (&vfs_default_singleton))
     {
       GVfs *singleton;

       singleton = _g_io_module_get_default (G_VFS_EXTENSION_POINT_NAME,
                                             "GIO_USE_VFS",
                                             (GIOModuleVerifyFunc) g_vfs_is_active);

       g_once_init_leave_pointer (&vfs_default_singleton, singleton);
     }

   return vfs_default_singleton;
 }

 /**
  * g_vfs_get_local:
  *
  * Gets the local #GVfs for the system.
  *
  * Returns: (transfer none): a #GVfs.
  */
 GVfs *
 g_vfs_get_local (void)
 {
   static GVfs *vfs = 0;

   if (g_once_init_enter_pointer (&vfs))
     g_once_init_leave_pointer (&vfs, _g_local_vfs_new ());

   return vfs;
 }

 /**
  * g_vfs_register_uri_scheme:
  * @vfs: a #GVfs
  * @scheme: an URI scheme, e.g. "http"
  * @uri_func: (scope notified) (nullable): a #GVfsFileLookupFunc
  * @uri_data: (nullable): custom data passed to be passed to @uri_func, or %NULL
  * @uri_destroy: (nullable): function to be called when unregistering the
  *     URI scheme, or when @vfs is disposed, to free the resources used
  *     by the URI lookup function
  * @parse_name_func: (scope notified) (nullable): a #GVfsFileLookupFunc
  * @parse_name_data: (nullable): custom data passed to be passed to
  *     @parse_name_func, or %NULL
  * @parse_name_destroy: (nullable): function to be called when unregistering the
  *     URI scheme, or when @vfs is disposed, to free the resources used
  *     by the parse name lookup function
  *
  * Registers @uri_func and @parse_name_func as the #GFile URI and parse name
  * lookup functions for URIs with a scheme matching @scheme.
  * Note that @scheme is registered only within the running application, as
  * opposed to desktop-wide as it happens with GVfs backends.
  *
  * When a #GFile is requested with an URI containing @scheme (e.g. through
  * g_file_new_for_uri()), @uri_func will be called to allow a custom
  * constructor. The implementation of @uri_func should not be blocking, and
  * must not call g_vfs_register_uri_scheme() or g_vfs_unregister_uri_scheme().
  *
  * When g_file_parse_name() is called with a parse name obtained from such file,
  * @parse_name_func will be called to allow the #GFile to be created again. In
  * that case, it's responsibility of @parse_name_func to make sure the parse
  * name matches what the custom #GFile implementation returned when
  * g_file_get_parse_name() was previously called. The implementation of
  * @parse_name_func should not be blocking, and must not call
  * g_vfs_register_uri_scheme() or g_vfs_unregister_uri_scheme().
  *
  * It's an error to call this function twice with the same scheme. To unregister
  * a custom URI scheme, use g_vfs_unregister_uri_scheme().
  *
  * Returns: %TRUE if @scheme was successfully registered, or %FALSE if a handler
  *     for @scheme already exists.
  *
  * Since: 2.50
  */
 gboolean
 g_vfs_register_uri_scheme (GVfs              *vfs,
                            const char        *scheme,
                            GVfsFileLookupFunc uri_func,
                            gpointer           uri_data,
                            GDestroyNotify     uri_destroy,
                            GVfsFileLookupFunc parse_name_func,
                            gpointer           parse_name_data,
                            GDestroyNotify     parse_name_destroy)
 {
   GVfsPrivate *priv;
   GVfsURISchemeData *closure;

   g_return_val_if_fail (G_IS_VFS (vfs), FALSE);
   g_return_val_if_fail (scheme != NULL, FALSE);

   priv = g_vfs_get_instance_private (vfs);

   g_rw_lock_reader_lock (&additional_schemes_lock);
   closure = g_hash_table_lookup (priv->additional_schemes, scheme);
   g_rw_lock_reader_unlock (&additional_schemes_lock);

   if (closure != NULL)
     return FALSE;

   closure = g_new0 (GVfsURISchemeData, 1);
   closure->uri_func = uri_func;
   closure->uri_data = uri_data;
   closure->uri_destroy = uri_destroy;
   closure->parse_name_func = parse_name_func;
   closure->parse_name_data = parse_name_data;
   closure->parse_name_destroy = parse_name_destroy;

   g_rw_lock_writer_lock (&additional_schemes_lock);
   g_hash_table_insert (priv->additional_schemes, g_strdup (scheme), closure);
   g_rw_lock_writer_unlock (&additional_schemes_lock);

   /* Invalidate supported schemes */
   g_clear_pointer (&priv->supported_schemes, g_free);

   return TRUE;
 }

 /**
  * g_vfs_unregister_uri_scheme:
  * @vfs: a #GVfs
  * @scheme: an URI scheme, e.g. "http"
  *
  * Unregisters the URI handler for @scheme previously registered with
  * g_vfs_register_uri_scheme().
  *
  * Returns: %TRUE if @scheme was successfully unregistered, or %FALSE if a
  *     handler for @scheme does not exist.
  *
  * Since: 2.50
  */
 gboolean
 g_vfs_unregister_uri_scheme (GVfs       *vfs,
                              const char *scheme)
 {
   GVfsPrivate *priv;
   gboolean res;

   g_return_val_if_fail (G_IS_VFS (vfs), FALSE);
   g_return_val_if_fail (scheme != NULL, FALSE);

   priv = g_vfs_get_instance_private (vfs);

   g_rw_lock_writer_lock (&additional_schemes_lock);
   res = g_hash_table_remove (priv->additional_schemes, scheme);
   g_rw_lock_writer_unlock (&additional_schemes_lock);

   if (res)
     {
       /* Invalidate supported schemes */
       g_clear_pointer (&priv->supported_schemes, g_free);

       return TRUE;
     }

   return FALSE;
 }
	/* GIO - GLib Input, Output and Streaming Library
	*
	* Copyright (C) 2006-2007 Red Hat, Inc.
	*
	* SPDX-License-Identifier: LGPL-2.1-or-later
	*
	* 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 2.1 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, see <http://www.gnu.org/licenses/>.
	*
	* Author: Alexander Larsson <alexl@redhat.com>
	*/

	#include "config.h"
	#include <string.h>
	#include "gvfs.h"
	#include "glib-private.h"
	#include "glocalvfs.h"
	#include "gresourcefile.h"
	#include "giomodule-priv.h"
	#include "glibintl.h"


	/**
	* GVfs:
	*
	* Entry point for using GIO functionality.
	*/

	static GRWLock additional_schemes_lock;

	typedef struct _GVfsPrivate {
	GHashTable *additional_schemes;
	char const **supported_schemes;
	} GVfsPrivate;

	typedef struct {
	GVfsFileLookupFunc uri_func;
	gpointer uri_data;
	GDestroyNotify uri_destroy;

	GVfsFileLookupFunc parse_name_func;
	gpointer parse_name_data;
	GDestroyNotify parse_name_destroy;
	} GVfsURISchemeData;

	G_DEFINE_TYPE_WITH_PRIVATE (GVfs, g_vfs, G_TYPE_OBJECT)

	static void
	g_vfs_dispose (GObject *object)
	{
	GVfs *vfs = G_VFS (object);
	GVfsPrivate *priv = g_vfs_get_instance_private (vfs);

	g_clear_pointer (&priv->additional_schemes, g_hash_table_destroy);
	g_clear_pointer (&priv->supported_schemes, g_free);

	G_OBJECT_CLASS (g_vfs_parent_class)->dispose (object);
	}

	static void
	g_vfs_class_init (GVfsClass *klass)
	{
	GObjectClass *object_class = G_OBJECT_CLASS (klass);
	object_class->dispose = g_vfs_dispose;
	}

	static GFile *
	resource_parse_name (GVfs *vfs,
	const char *parse_name,
	gpointer user_data)
	{
	if (g_str_has_prefix (parse_name, "resource:"))
	return _g_resource_file_new (parse_name);

	return NULL;
	}

	static GFile *
	resource_get_file_for_uri (GVfs *vfs,
	const char *uri,
	gpointer user_data)
	{
	return _g_resource_file_new (uri);
	}

	static void
	g_vfs_uri_lookup_func_closure_free (gpointer data)
	{
	GVfsURISchemeData *closure = data;

	if (closure->uri_destroy)
	closure->uri_destroy (closure->uri_data);
	if (closure->parse_name_destroy)
	closure->parse_name_destroy (closure->parse_name_data);

	g_free (closure);
	}

	static void
	g_vfs_init (GVfs *vfs)
	{
	GVfsPrivate *priv = g_vfs_get_instance_private (vfs);
	priv->additional_schemes =
	g_hash_table_new_full (g_str_hash, g_str_equal,
	g_free, g_vfs_uri_lookup_func_closure_free);

	g_vfs_register_uri_scheme (vfs, "resource",
	resource_get_file_for_uri, NULL, NULL,
	resource_parse_name, NULL, NULL);
	}

	/**
	* g_vfs_is_active:
	* @vfs: a #GVfs.
	*
	* Checks if the VFS is active.
	*
	* Returns: %TRUE if construction of the @vfs was successful
	* and it is now active.
	*/
	gboolean
	g_vfs_is_active (GVfs *vfs)
	{
	GVfsClass *class;

	g_return_val_if_fail (G_IS_VFS (vfs), FALSE);

	class = G_VFS_GET_CLASS (vfs);

	return (* class->is_active) (vfs);
	}


	/**
	* g_vfs_get_file_for_path:
	* @vfs: a #GVfs.
	* @path: a string containing a VFS path.
	*
	* Gets a #GFile for @path.
	*
	* Returns: (transfer full): a #GFile.
	* Free the returned object with g_object_unref().
	*/
	GFile *
	g_vfs_get_file_for_path (GVfs *vfs,
	const char *path)
	{
	GVfsClass *class;

	g_return_val_if_fail (G_IS_VFS (vfs), NULL);
	g_return_val_if_fail (path != NULL, NULL);

	class = G_VFS_GET_CLASS (vfs);

	return (* class->get_file_for_path) (vfs, path);
	}

	static GFile *
	parse_name_internal (GVfs *vfs,
	const char *parse_name)
	{
	GVfsPrivate *priv = g_vfs_get_instance_private (vfs);
	GHashTableIter iter;
	GVfsURISchemeData *closure;
	GFile *ret = NULL;

	g_rw_lock_reader_lock (&additional_schemes_lock);
	g_hash_table_iter_init (&iter, priv->additional_schemes);

	while (g_hash_table_iter_next (&iter, NULL, (gpointer *) &closure))
	{
	ret = closure->parse_name_func (vfs, parse_name,
	closure->parse_name_data);

	if (ret)
	break;
	}

	g_rw_lock_reader_unlock (&additional_schemes_lock);

	return ret;
	}

	static GFile *
	get_file_for_uri_internal (GVfs *vfs,
	const char *uri)
	{
	GVfsPrivate *priv = g_vfs_get_instance_private (vfs);
	GFile *ret = NULL;
	char *scheme;
	GVfsURISchemeData *closure;

	scheme = g_uri_parse_scheme (uri);
	if (scheme == NULL)
	return NULL;

	g_rw_lock_reader_lock (&additional_schemes_lock);
	closure = g_hash_table_lookup (priv->additional_schemes, scheme);

	if (closure)
	ret = closure->uri_func (vfs, uri, closure->uri_data);

	g_rw_lock_reader_unlock (&additional_schemes_lock);

	g_free (scheme);
	return ret;
	}

	/**
	* g_vfs_get_file_for_uri:
	* @vfs: a#GVfs.
	* @uri: a string containing a URI
	*
	* Gets a #GFile for @uri.
	*
	* This operation never fails, but the returned object
	* might not support any I/O operation if the URI
	* is malformed or if the URI scheme is not supported.
	*
	* Returns: (transfer full): a #GFile.
	* Free the returned object with g_object_unref().
	*/
	GFile *
	g_vfs_get_file_for_uri (GVfs *vfs,
	const char *uri)
	{
	GVfsClass *class;
	GFile *ret = NULL;

	g_return_val_if_fail (G_IS_VFS (vfs), NULL);
	g_return_val_if_fail (uri != NULL, NULL);

	class = G_VFS_GET_CLASS (vfs);

	ret = get_file_for_uri_internal (vfs, uri);
	if (!ret)
	ret = (* class->get_file_for_uri) (vfs, uri);

	g_assert (ret != NULL);

	return g_steal_pointer (&ret);
	}

	/**
	* g_vfs_get_supported_uri_schemes:
	* @vfs: a #GVfs.
	*
	* Gets a list of URI schemes supported by @vfs.
	*
	* Returns: (transfer none): a %NULL-terminated array of strings.
	* The returned array belongs to GIO and must
	* not be freed or modified.
	*/
	const gchar * const *
	g_vfs_get_supported_uri_schemes (GVfs *vfs)
	{
	GVfsPrivate *priv;

	g_return_val_if_fail (G_IS_VFS (vfs), NULL);

	priv = g_vfs_get_instance_private (vfs);

	if (!priv->supported_schemes)
	{
	GVfsClass *class;
	const char * const *default_schemes;
	const char *additional_scheme;
	GPtrArray *supported_schemes;
	GHashTableIter iter;

	class = G_VFS_GET_CLASS (vfs);

	default_schemes = (* class->get_supported_uri_schemes) (vfs);
	supported_schemes = g_ptr_array_new ();

	for (; default_schemes && *default_schemes; default_schemes++)
	g_ptr_array_add (supported_schemes, (gpointer) *default_schemes);

	g_rw_lock_reader_lock (&additional_schemes_lock);
	g_hash_table_iter_init (&iter, priv->additional_schemes);

	while (g_hash_table_iter_next
	(&iter, (gpointer *) &additional_scheme, NULL))
	g_ptr_array_add (supported_schemes, (gpointer) additional_scheme);

	g_rw_lock_reader_unlock (&additional_schemes_lock);

	g_ptr_array_add (supported_schemes, NULL);

	g_free (priv->supported_schemes);
	priv->supported_schemes =
	(char const **) g_ptr_array_free (supported_schemes, FALSE);
	}

	return priv->supported_schemes;
	}

	/**
	* g_vfs_parse_name:
	* @vfs: a #GVfs.
	* @parse_name: a string to be parsed by the VFS module.
	*
	* This operation never fails, but the returned object might
	* not support any I/O operations if the @parse_name cannot
	* be parsed by the #GVfs module.
	*
	* Returns: (transfer full): a #GFile for the given @parse_name.
	* Free the returned object with g_object_unref().
	*/
	GFile *
	g_vfs_parse_name (GVfs *vfs,
	const char *parse_name)
	{
	GVfsClass *class;
	GFile *ret;

	g_return_val_if_fail (G_IS_VFS (vfs), NULL);
	g_return_val_if_fail (parse_name != NULL, NULL);

	class = G_VFS_GET_CLASS (vfs);

	ret = parse_name_internal (vfs, parse_name);
	if (ret)
	return ret;

	return (* class->parse_name) (vfs, parse_name);
	}

	static GVfs vfs_default_singleton = NULL; / (owned) (atomic) */

	/**
	* g_vfs_get_default:
	*
	* Gets the default #GVfs for the system.
	*
	* Returns: (not nullable) (transfer none): a #GVfs, which will be the local
	* file system #GVfs if no other implementation is available.
	*/
	GVfs *
	g_vfs_get_default (void)
	{
	if (GLIB_PRIVATE_CALL (g_check_setuid) ())
	return g_vfs_get_local ();

	if (g_once_init_enter_pointer (&vfs_default_singleton))
	{
	GVfs *singleton;

	singleton = _g_io_module_get_default (G_VFS_EXTENSION_POINT_NAME,
	"GIO_USE_VFS",
	(GIOModuleVerifyFunc) g_vfs_is_active);

	g_once_init_leave_pointer (&vfs_default_singleton, singleton);
	}

	return vfs_default_singleton;
	}

	/**
	* g_vfs_get_local:
	*
	* Gets the local #GVfs for the system.
	*
	* Returns: (transfer none): a #GVfs.
	*/
	GVfs *
	g_vfs_get_local (void)
	{
	static GVfs *vfs = 0;

	if (g_once_init_enter_pointer (&vfs))
	g_once_init_leave_pointer (&vfs, _g_local_vfs_new ());

	return vfs;
	}

	/**
	* g_vfs_register_uri_scheme:
	* @vfs: a #GVfs
	* @scheme: an URI scheme, e.g. "http"
	* @uri_func: (scope notified) (nullable): a #GVfsFileLookupFunc
	* @uri_data: (nullable): custom data passed to be passed to @uri_func, or %NULL
	* @uri_destroy: (nullable): function to be called when unregistering the
	* URI scheme, or when @vfs is disposed, to free the resources used
	* by the URI lookup function
	* @parse_name_func: (scope notified) (nullable): a #GVfsFileLookupFunc
	* @parse_name_data: (nullable): custom data passed to be passed to
	* @parse_name_func, or %NULL
	* @parse_name_destroy: (nullable): function to be called when unregistering the
	* URI scheme, or when @vfs is disposed, to free the resources used
	* by the parse name lookup function
	*
	* Registers @uri_func and @parse_name_func as the #GFile URI and parse name
	* lookup functions for URIs with a scheme matching @scheme.
	* Note that @scheme is registered only within the running application, as
	* opposed to desktop-wide as it happens with GVfs backends.
	*
	* When a #GFile is requested with an URI containing @scheme (e.g. through
	* g_file_new_for_uri()), @uri_func will be called to allow a custom
	* constructor. The implementation of @uri_func should not be blocking, and
	* must not call g_vfs_register_uri_scheme() or g_vfs_unregister_uri_scheme().
	*
	* When g_file_parse_name() is called with a parse name obtained from such file,
	* @parse_name_func will be called to allow the #GFile to be created again. In
	* that case, it's responsibility of @parse_name_func to make sure the parse
	* name matches what the custom #GFile implementation returned when
	* g_file_get_parse_name() was previously called. The implementation of
	* @parse_name_func should not be blocking, and must not call
	* g_vfs_register_uri_scheme() or g_vfs_unregister_uri_scheme().
	*
	* It's an error to call this function twice with the same scheme. To unregister
	* a custom URI scheme, use g_vfs_unregister_uri_scheme().
	*
	* Returns: %TRUE if @scheme was successfully registered, or %FALSE if a handler
	* for @scheme already exists.
	*
	* Since: 2.50
	*/
	gboolean
	g_vfs_register_uri_scheme (GVfs *vfs,
	const char *scheme,
	GVfsFileLookupFunc uri_func,
	gpointer uri_data,
	GDestroyNotify uri_destroy,
	GVfsFileLookupFunc parse_name_func,
	gpointer parse_name_data,
	GDestroyNotify parse_name_destroy)
	{
	GVfsPrivate *priv;
	GVfsURISchemeData *closure;

	g_return_val_if_fail (G_IS_VFS (vfs), FALSE);
	g_return_val_if_fail (scheme != NULL, FALSE);

	priv = g_vfs_get_instance_private (vfs);

	g_rw_lock_reader_lock (&additional_schemes_lock);
	closure = g_hash_table_lookup (priv->additional_schemes, scheme);
	g_rw_lock_reader_unlock (&additional_schemes_lock);

	if (closure != NULL)
	return FALSE;

	closure = g_new0 (GVfsURISchemeData, 1);
	closure->uri_func = uri_func;
	closure->uri_data = uri_data;
	closure->uri_destroy = uri_destroy;
	closure->parse_name_func = parse_name_func;
	closure->parse_name_data = parse_name_data;
	closure->parse_name_destroy = parse_name_destroy;

	g_rw_lock_writer_lock (&additional_schemes_lock);
	g_hash_table_insert (priv->additional_schemes, g_strdup (scheme), closure);
	g_rw_lock_writer_unlock (&additional_schemes_lock);

	/* Invalidate supported schemes */
	g_clear_pointer (&priv->supported_schemes, g_free);

	return TRUE;
	}

	/**
	* g_vfs_unregister_uri_scheme:
	* @vfs: a #GVfs
	* @scheme: an URI scheme, e.g. "http"
	*
	* Unregisters the URI handler for @scheme previously registered with
	* g_vfs_register_uri_scheme().
	*
	* Returns: %TRUE if @scheme was successfully unregistered, or %FALSE if a
	* handler for @scheme does not exist.
	*
	* Since: 2.50
	*/
	gboolean
	g_vfs_unregister_uri_scheme (GVfs *vfs,
	const char *scheme)
	{
	GVfsPrivate *priv;
	gboolean res;

	g_return_val_if_fail (G_IS_VFS (vfs), FALSE);
	g_return_val_if_fail (scheme != NULL, FALSE);

	priv = g_vfs_get_instance_private (vfs);

	g_rw_lock_writer_lock (&additional_schemes_lock);
	res = g_hash_table_remove (priv->additional_schemes, scheme);
	g_rw_lock_writer_unlock (&additional_schemes_lock);

	if (res)
	{
	/* Invalidate supported schemes */
	g_clear_pointer (&priv->supported_schemes, g_free);

	return TRUE;
	}

	return FALSE;
	}