path: root/src/ephy-extensions-manager.c

/*
 *  Copyright (C) 2003 Marco Pesenti Gritti
 *  Copyright (C) 2003, 2004 Christian Persch
 *  Copyright (C) 2004 Adam Hooper
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 *  $Id$
 */

#include "config.h"

#include "ephy-extensions-manager.h"

#include "ephy-loader.h"
#include "ephy-shlib-loader.h"

#include "ephy-node-db.h"
#include "ephy-shell.h"
#include "eel-gconf-extensions.h"
#include "ephy-file-helpers.h"
#include "ephy-object-helpers.h"
#include "ephy-debug.h"

#include <libxml/tree.h>
#include <libxml/xmlreader.h>

#include <libgnomevfs/gnome-vfs-ops.h>
#include <libgnomevfs/gnome-vfs-utils.h>

#include <gconf/gconf-client.h>

#include <gmodule.h>
#include <dirent.h>
#include <string.h>

/* define to validate the extensions files */
/* #define ENABLE_VALIDATION */

#ifdef ENABLE_VALIDATION
#include <libxml/xmlschemas.h>
#endif

#ifdef ENABLE_PYTHON
#include "ephy-python-extension.h"
#include "ephy-python-loader.h"
#endif

#define CONF_LOADED_EXTENSIONS  "/apps/epiphany/general/active_extensions"
#define SCHEMA_FILE     "/epiphany-extension.xsd"

#define EPHY_EXTENSIONS_MANAGER_GET_PRIVATE(object)(G_TYPE_INSTANCE_GET_PRIVATE ((object), EPHY_TYPE_EXTENSIONS_MANAGER, EphyExtensionsManagerPrivate))

struct _EphyExtensionsManagerPrivate
{
    gboolean initialised;

    GList *data;
    GList *factories;
    GList *extensions;
    GList *dir_monitors;
    GList *windows;
    guint active_extensions_notifier_id;

#ifdef ENABLE_VALIDATION
    xmlSchemaPtr schema;
    xmlSchemaValidCtxtPtr schema_ctxt;
#endif
};

typedef struct
{
    EphyExtensionInfo info;
    guint version;
    gboolean load_deferred;
    gboolean load_failed;

    xmlChar *gettext_domain;
    xmlChar *locale_directory;
    xmlChar *loader_type;
    GData *loader_attributes;

    EphyLoader *loader; /* NULL if never loaded */
    GObject *extension; /* NULL if unloaded */
} ExtensionInfo;

typedef struct
{
    char *type;
    EphyLoader *loader;
} LoaderInfo;

enum
{
    CHANGED,
    ADDED,
    REMOVED,
    LAST_SIGNAL
};

static guint signals[LAST_SIGNAL] = { 0 };

static GObjectClass *parent_class = NULL;

static void ephy_extensions_manager_class_init  (EphyExtensionsManagerClass *klass);
static void ephy_extensions_manager_iface_init  (EphyExtensionIface *iface);
static void ephy_extensions_manager_init    (EphyExtensionsManager *manager);

GType
ephy_extensions_manager_get_type (void)
{
    static GType type = 0;

    if (G_UNLIKELY (type == 0))
    {
        static const GTypeInfo our_info =
        {
            sizeof (EphyExtensionsManagerClass),
            NULL, /* base_init */
            NULL, /* base_finalize */
            (GClassInitFunc) ephy_extensions_manager_class_init,
            NULL,
            NULL, /* class_data */
            sizeof (EphyExtensionsManager),
            0, /* n_preallocs */
            (GInstanceInitFunc) ephy_extensions_manager_init
        };

        static const GInterfaceInfo extension_info =
        {
            (GInterfaceInitFunc) ephy_extensions_manager_iface_init,
            NULL,
            NULL
        };

        type = g_type_register_static (G_TYPE_OBJECT,
                           "EphyExtensionsManager",
                           &our_info, 0);

        g_type_add_interface_static (type,
                         EPHY_TYPE_EXTENSION,
                         &extension_info);
    }

    return type;
}

/**
 * ephy_extensions_manager_load:
 * @manager: an #EphyExtensionsManager
 * @name: identifier of the extension to load
 *
 * Loads the @name extension.
 **/
void
ephy_extensions_manager_load (EphyExtensionsManager *manager,
                  const char *identifier)
{
    GSList *gconf_exts;

    g_return_if_fail (EPHY_IS_EXTENSIONS_MANAGER (manager));
    g_return_if_fail (identifier != NULL);

    LOG ("Adding '%s' to extensions", identifier);

    gconf_exts = eel_gconf_get_string_list (CONF_LOADED_EXTENSIONS);

    if (!g_slist_find_custom (gconf_exts, identifier, (GCompareFunc) strcmp))
    {
        gconf_exts = g_slist_prepend (gconf_exts, g_strdup (identifier));

        eel_gconf_set_string_list (CONF_LOADED_EXTENSIONS, gconf_exts);
    }

    g_slist_foreach (gconf_exts, (GFunc) g_free, NULL);
    g_slist_free (gconf_exts);
}

/**
 * ephy_extensions_manager_unload:
 * @manager: an #EphyExtensionsManager
 * @name: filename of extension to unload, minus "lib" and "extension.so"
 *
 * Unloads the extension specified by @name.
 *
 * The extension with the same filename can afterwards be reloaded. However,
 * if any GTypes within the extension have changed parent types, Epiphany must
 * be restarted.
 **/
void
ephy_extensions_manager_unload (EphyExtensionsManager *manager,
                const char *identifier)
{
    GSList *gconf_exts;
    GSList *l;

    g_return_if_fail (EPHY_IS_EXTENSIONS_MANAGER (manager));
    g_return_if_fail (identifier != NULL);

    LOG ("Removing '%s' from extensions", identifier);

    gconf_exts = eel_gconf_get_string_list (CONF_LOADED_EXTENSIONS);

    l = g_slist_find_custom (gconf_exts, identifier, (GCompareFunc) strcmp);

    if (l != NULL)
    {
        gconf_exts = g_slist_remove_link (gconf_exts, l);
        g_free (l->data);
        g_slist_free_1 (l);

        eel_gconf_set_string_list (CONF_LOADED_EXTENSIONS, gconf_exts);
    }

    g_slist_foreach (gconf_exts, (GFunc) g_free, NULL);
    g_slist_free (gconf_exts);
}

/**
 * ephy_extensions_manager_register:
 * @manager: an #EphyExtensionsManager
 * @object: an Extension
 *
 * Registers @object with the extensions manager. @object must implement the
 * #EphyExtension interface.
 **/
void
ephy_extensions_manager_register (EphyExtensionsManager *manager,
                  GObject *object)
{
    g_return_if_fail (EPHY_IS_EXTENSIONS_MANAGER (manager));
    g_return_if_fail (EPHY_IS_EXTENSION (object));

    manager->priv->extensions = g_list_prepend (manager->priv->extensions,
                            g_object_ref (object));
}


/**
 * ephy_extensions_manager_get_extensions:
 * @manager: an #EphyExtensionsManager
 *
 * Returns the list of known extensions.
 *
 * Returns: a list of #EphyExtensionInfo
 **/
GList *
ephy_extensions_manager_get_extensions (EphyExtensionsManager *manager)
{
    return g_list_copy (manager->priv->data);
}

static void
free_extension_info (ExtensionInfo *info)
{
    EphyExtensionInfo *einfo = (EphyExtensionInfo *) info;

    g_free (einfo->identifier);
    xmlFree ((xmlChar *) einfo->name);
    xmlFree ((xmlChar *) einfo->description);
    g_list_foreach (einfo->authors, (GFunc) xmlFree, NULL);
    g_list_free (einfo->authors);
    xmlFree ((xmlChar *) einfo->url);
    xmlFree ((xmlChar *) info->gettext_domain);
    xmlFree ((xmlChar *) info->locale_directory);
    xmlFree ((xmlChar *) info->loader_type);
    g_datalist_clear (&info->loader_attributes);

    if (info->extension != NULL)
    {
        g_return_if_fail (info->loader != NULL);

        ephy_loader_release_object (info->loader, info->extension);
    }
    if (info->loader != NULL)
    {
        g_object_unref (info->loader);
    }

    g_free (info);
}

static void
free_loader_info (LoaderInfo *info)
{
    g_free (info->type);
    g_object_unref (info->loader);
    g_free (info);
}

static int
find_extension_info (const ExtensionInfo *info,
             const char *identifier)
{
    return strcmp (info->info.identifier, identifier);
}

typedef struct
{
    xmlChar *string;
    guint match;
} LocalisedString;

static const char * const *languages = NULL;

static void
assign_localised_string (xmlTextReaderPtr reader,
             LocalisedString *string)
{
    const xmlChar *value, *lang;
    guint i;

    lang = xmlTextReaderConstXmlLang (reader);
    value = xmlTextReaderConstValue (reader);

    if (G_UNLIKELY (lang == NULL))
    {
        /* languages always has "C" in it, so make sure we get a match */
        lang = (const xmlChar *) "C";
    }

    for (i = 0; languages[i] != NULL && i < string->match; i++)
    {
        if (lang != NULL &&
            strcmp ((const char *) lang, languages[i]) == 0)
        {
            xmlFree (string->string);
            string->string = xmlStrdup (value);
            string->match = i;
            break;
        }
    }
}

typedef enum
{
    STATE_START,
    STATE_STOP,
    STATE_ERROR,
    STATE_EXTENSION,
    STATE_NAME,
    STATE_DESCRIPTION,
    STATE_VERSION,
    STATE_AUTHOR,
    STATE_URL,
    STATE_GETTEXT_DOMAIN,
    STATE_LOCALE_DIRECTORY,
    STATE_LOADER,
    STATE_LOADER_ATTRIBUTE,
    STATE_LOAD_DEFERRED,
} ParserState;

static void
ephy_extensions_manager_load_string (EphyExtensionsManager *manager,
                     const char *identifier,
                     /* const */ char *xml)
{
    xmlDocPtr doc;
    xmlTextReaderPtr reader;
    ParserState state = STATE_START;
    GQuark attr_quark = 0;
    EphyExtensionInfo *einfo;
    ExtensionInfo *info;
    int ret;
    LocalisedString description = { NULL, G_MAXUINT };
    LocalisedString name = { NULL, G_MAXUINT };

    LOG ("Loading description file for '%s'", identifier);

    if (g_list_find_custom (manager->priv->data, identifier,
                (GCompareFunc) find_extension_info) != NULL)
    {
        g_warning ("Extension description for '%s' already read!",
               identifier);
        return;
    }

    /* FIXME: Ideally we'd put the schema validator in the reader. libxml2
     * doesn't seem to support that at this point in time, so we've got to
     * put the schema validation on the Doc Tree and then pass that to the
     * reader. (maybe switch to RelaxNG?)
     */
    doc = xmlParseDoc ((xmlChar *) xml);

    if (doc == NULL)
    {
        g_warning ("Couldn't read '%s' data\n", identifier);
        return;
    }
#ifdef ENABLE_VALIDATION
    /* Validate the extension description */
    if (manager->priv->schema_ctxt)
    {
        if (xmlSchemaValidateDoc (manager->priv->schema_ctxt, doc))
        {
            g_warning ("Validation errors in '%s' data",
                   identifier);
            xmlFreeDoc (doc);
            return;
        }
    }
#endif
    /* Now parse it */
    reader = xmlReaderWalker (doc);
    g_return_if_fail (reader != NULL);

    info = g_new0 (ExtensionInfo, 1);
    einfo = (EphyExtensionInfo *) info;
    einfo->identifier = g_strdup (identifier);
    g_datalist_init (&info->loader_attributes);

    ret = xmlTextReaderRead (reader);

    while (ret == 1)
    {
        const xmlChar *tag;
        xmlReaderTypes type;

        tag = xmlTextReaderConstName (reader);
        type = xmlTextReaderNodeType (reader);

        if (state == STATE_LOADER &&
            type == XML_READER_TYPE_ELEMENT &&
            xmlStrEqual (tag, (const xmlChar *) "attribute"))
        {
            xmlChar *name;

            state = STATE_LOADER_ATTRIBUTE;

            name = xmlTextReaderGetAttribute (reader, (const xmlChar *) "name");
            attr_quark = g_quark_from_string ((const char *) name);
            xmlFree (name);
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "author"))
        {
            state = STATE_AUTHOR;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "description"))
        {
            state = STATE_DESCRIPTION;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "gettext-domain"))
        {
            state = STATE_GETTEXT_DOMAIN;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "load-deferred"))
        {
            state = STATE_LOAD_DEFERRED;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "locale-directory"))
        {
            state = STATE_LOCALE_DIRECTORY;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "name"))
        {
            state = STATE_NAME;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "url"))
        {
            state = STATE_URL;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "version"))
        {
            state = STATE_VERSION;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "loader"))
        {
            state = STATE_LOADER;

            info->loader_type = xmlTextReaderGetAttribute (reader, (const xmlChar *) "type");
        }
        else if (state == STATE_LOADER_ATTRIBUTE &&
             type == XML_READER_TYPE_TEXT &&
             attr_quark != 0)
        {
            xmlChar *value;

            value = xmlTextReaderValue (reader);

            g_datalist_id_set_data_full (&info->loader_attributes,
                             attr_quark, value,
                             (GDestroyNotify) xmlFree);
            attr_quark = 0;
        }
        else if (state == STATE_LOADER_ATTRIBUTE &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "attribute"))
        {
            state = STATE_LOADER;
        }
        else if (state == STATE_AUTHOR &&
             type == XML_READER_TYPE_TEXT)
        {
            einfo->authors = g_list_prepend
                (einfo->authors, xmlTextReaderValue (reader));
        }
        else if (state == STATE_DESCRIPTION &&
             type == XML_READER_TYPE_TEXT)
        {
            assign_localised_string (reader, &description);
        }
        else if (state == STATE_GETTEXT_DOMAIN &&
             type == XML_READER_TYPE_TEXT)
        {
            info->gettext_domain = xmlTextReaderValue (reader);
        }
        else if (state == STATE_LOAD_DEFERRED &&
             type == XML_READER_TYPE_TEXT)
        {
            const xmlChar *value;

            value = xmlTextReaderConstValue (reader);
            info->load_deferred =
                (value != NULL && xmlStrEqual (value, (const xmlChar *) "true"));
        }
        else if (state == STATE_LOCALE_DIRECTORY &&
             type == XML_READER_TYPE_TEXT)
        {
            info->locale_directory = xmlTextReaderValue (reader);
        }
        else if (state == STATE_NAME &&
             type == XML_READER_TYPE_TEXT)
        {
            assign_localised_string (reader, &name);
        }
        else if (state == STATE_VERSION &&
             type == XML_READER_TYPE_TEXT)
        {
            info->version = (guint) strtol ((const char *) xmlTextReaderConstValue (reader), NULL, 10);
        }
        else if (state == STATE_URL &&
             type == XML_READER_TYPE_TEXT)
        {
            einfo->url = (char *)xmlTextReaderValue (reader);
        }
        else if (state == STATE_AUTHOR &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "author"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_DESCRIPTION &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "description"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_GETTEXT_DOMAIN &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "gettext-domain"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_LOCALE_DIRECTORY &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "locale-directory"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_LOADER &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "loader"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_NAME &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "name"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_URL &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "url"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_VERSION &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "version"))
        {
            state = STATE_EXTENSION;
        }
        else if (type == XML_READER_TYPE_SIGNIFICANT_WHITESPACE ||
             type == XML_READER_TYPE_WHITESPACE ||
             type == XML_READER_TYPE_TEXT)
        {
            /* eat it */
        }
        else if (state == STATE_START &&
             type == XML_READER_TYPE_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "extension"))
        {
            state = STATE_EXTENSION;
        }
        else if (state == STATE_EXTENSION &&
             type == XML_READER_TYPE_END_ELEMENT &&
             xmlStrEqual (tag, (const xmlChar *) "extension"))
        {
            state = STATE_STOP;
        }
        else
        {
            const xmlChar *content;

            content = xmlTextReaderConstValue (reader);
            g_warning ("tag '%s' of type %d in state %d with content '%s' was unexpected!",
                   tag, type, state, content ? (char *) content : "(null)");

            state = STATE_ERROR;
            break;
        }

        ret = xmlTextReaderRead (reader);
    }

    xmlFreeTextReader (reader);
    xmlFreeDoc (doc);

    /* assign localised strings */
    einfo->description = (char *)description.string;
    einfo->name = (char *)name.string;

    /* sanity check */
    if (ret < 0 || state != STATE_STOP ||
        einfo->name == NULL || einfo->description == NULL ||
        info->loader_type == NULL || info->loader_type[0] == '\0')
    {
        free_extension_info (info);
        return;
    }

    manager->priv->data = g_list_prepend (manager->priv->data, info);

    g_signal_emit (manager, signals[ADDED], 0, info);
}

static char *
path_to_identifier (const char *path)
{
    char *identifier, *dot;

    identifier = g_path_get_basename (path);
    dot = strstr (identifier, ".xml");
    g_return_val_if_fail (dot != NULL, NULL);

    *dot = '\0';

    return identifier;
}

static void
ephy_extensions_manager_load_file (EphyExtensionsManager *manager,
                   const char *path)
{
    char *identifier;
    char *xml;
    GError *err = NULL;

    g_file_get_contents (path, &xml, NULL, &err);

    if (err != NULL)
    {
        g_warning ("Could not read file at '%s': '%s'",
               path, err->message);
        g_error_free (err);
        return;
    }

    identifier = path_to_identifier (path);
    g_return_if_fail (identifier != NULL);

    ephy_extensions_manager_load_string (manager, identifier, xml);

    g_free (identifier);
    g_free (xml);
}

static int
find_loader (const LoaderInfo *info,
          const char *type)
{
    return strcmp (info->type, type);
}

static char *
sanitise_type (const char *string)
{
    char *str, *p;

    str = g_strdup (string);
    for (p = str; *p != '\0'; p++)
    {
        if (!g_ascii_isalpha (*p)) *p = '-';
    }

    return str;
}

static EphyLoader *
get_loader_for_type (EphyExtensionsManager *manager,
             const char *type)
{
    LoaderInfo *info;
    GList *l;
    GData *attr = NULL;
    char *path, *name, *stype;
    EphyLoader *shlib_loader;
    GObject *loader;

    LOG ("Looking for loader for type '%s'", type);

    l = g_list_find_custom (manager->priv->factories, type,
                (GCompareFunc) find_loader);
    if (l != NULL)
    {
        info = (LoaderInfo *) l->data;
        return g_object_ref (info->loader);
    }

    if (strcmp (type, "shlib") == 0)
    {
        info = g_new (LoaderInfo, 1);
        info->type = g_strdup (type);
        info->loader = g_object_new (EPHY_TYPE_SHLIB_LOADER, NULL);

        manager->priv->factories =
            g_list_append (manager->priv->factories, info);

        return g_object_ref (info->loader);
    }
    if (strcmp (type, "python") == 0)
    {
#ifdef ENABLE_PYTHON
        info = g_new (LoaderInfo, 1);
        info->type = g_strdup (type);
        info->loader = g_object_new (EPHY_TYPE_PYTHON_LOADER, NULL);

        manager->priv->factories =
                g_list_append (manager->priv->factories, info);

        return g_object_ref (info->loader);
#else
        return NULL;
#endif
    }

    stype = sanitise_type (type);
    name = g_strconcat ("lib", stype, "loader.", G_MODULE_SUFFIX, NULL);
    path = g_build_filename (LOADER_DIR, name, NULL);
    g_datalist_init (&attr);
    g_datalist_set_data (&attr, "library", path);

    shlib_loader = get_loader_for_type (manager, "shlib");
    g_return_val_if_fail (shlib_loader != NULL, NULL);

    loader = ephy_loader_get_object (shlib_loader, &attr);
    g_datalist_clear (&attr);
    g_free (stype);
    g_free (name);
    g_free (path);

    if (EPHY_IS_LOADER (loader))
    {
        info = g_new (LoaderInfo, 1);
        info->type = g_strdup (type);
        info->loader = EPHY_LOADER (loader);

        manager->priv->factories =
            g_list_append (manager->priv->factories, info);

        return g_object_ref (info->loader);
    }

    g_return_val_if_reached (NULL);

    return NULL;
}

static void
attach_window (EphyWindow *window,
           EphyExtension *extension)
{
    GList *tabs, *l;

    ephy_extension_attach_window (extension, window);

    tabs = ephy_window_get_tabs (window);
    for (l = tabs; l; l = l->next)
    {
        ephy_extension_attach_tab (extension, window,
                       EPHY_TAB (l->data));
    }
    g_list_free (tabs);
}

static void
load_extension (EphyExtensionsManager *manager,
        ExtensionInfo *info)
{
    EphyLoader *loader;

    g_return_if_fail (info->extension == NULL);

    LOG ("Loading extension '%s'", info->info.identifier);

    /* don't try again */
    if (info->load_failed) return;

    /* get a loader */
    loader = get_loader_for_type (manager, (const char *)info->loader_type);
    if (loader == NULL)
    {
        g_message ("No loader found for extension '%s' of type '%s'\n",
               info->info.identifier, info->loader_type);
        return;
    }

    info->loader = loader;

    info->extension = ephy_loader_get_object (loader,
                           &info->loader_attributes);

    /* attach if the extension implements EphyExtensionIface */
    if (EPHY_IS_EXTENSION (info->extension))
    {
        manager->priv->extensions =
            g_list_prepend (manager->priv->extensions,
                    g_object_ref (info->extension));

        g_list_foreach (manager->priv->windows, (GFunc) attach_window,
                info->extension);
    }

    if (info->extension != NULL)
    {
        info->info.active = TRUE;

        g_signal_emit (manager, signals[CHANGED], 0, info);
    }
    else
    {
        info->info.active = FALSE;
        info->load_failed = TRUE;
    }
}

static void
detach_window (EphyWindow *window,
           EphyExtension *extension)
{
    GList *tabs, *l;

    tabs = ephy_window_get_tabs (window);
    for (l = tabs; l; l = l->next)
    {
        ephy_extension_detach_tab (extension, window,
                       EPHY_TAB (l->data));
    }
    g_list_free (tabs);

    ephy_extension_detach_window (extension, window);
}

static void
unload_extension (EphyExtensionsManager *manager,
          ExtensionInfo *info)
{
    g_return_if_fail (info->loader != NULL);
    g_return_if_fail (info->extension != NULL || info->load_failed);

    LOG ("Unloading extension '%s'", info->info.identifier);

    if (info->load_failed) return;

    /* detach if the extension implements EphyExtensionIface */
    if (EPHY_IS_EXTENSION (info->extension))
    {
        g_list_foreach (manager->priv->windows, (GFunc) detach_window,
                info->extension);

        manager->priv->extensions =
            g_list_remove (manager->priv->extensions, info->extension);

        /* we own two refs to the extension, the one we added when
         * we added it to the priv->extensions list, and the one returned
         * from get_object. Release object, and queue a unref, since if the
         * extension has its own functions queued in the idle loop, the
         * functions must exist in memory before being called.
         */
        ephy_object_idle_unref (info->extension);
    }

    ephy_loader_release_object (info->loader, G_OBJECT (info->extension));

    info->info.active = FALSE;
    info->extension = NULL;

    g_signal_emit (manager, signals[CHANGED], 0, info);
}

static void
sync_loaded_extensions (EphyExtensionsManager *manager)
{
    GConfClient *client;
    GConfValue *value;
    GSList *active_extensions = NULL;
    GList *l;
    gboolean active;
    ExtensionInfo *info;

    LOG ("Synching changed list of active extensions");

    client = gconf_client_get_default ();
    g_return_if_fail (client != NULL);

    value = gconf_client_get (client, CONF_LOADED_EXTENSIONS, NULL);

    /* make sure the extensions-manager-ui is loaded */
    if (value == NULL ||
        value->type != GCONF_VALUE_LIST ||
        gconf_value_get_list_type (value) != GCONF_VALUE_STRING)
    {
        active_extensions = g_slist_prepend (active_extensions,
                             g_strdup ("extensions-manager-ui"));
        eel_gconf_set_string_list (CONF_LOADED_EXTENSIONS, active_extensions);
    }
    else
    {
        active_extensions = eel_gconf_get_string_list (CONF_LOADED_EXTENSIONS);
    }

    for (l = manager->priv->data; l != NULL; l = l->next)
    {
        info = (ExtensionInfo *) l->data;

        active = (g_slist_find_custom (active_extensions,
                           info->info.identifier,
                           (GCompareFunc) strcmp) != NULL);

        LOG ("Extension '%s' is %sactive and %sloaded",
             info->info.identifier,
             active ? "" : "not ",
             info->info.active ? "" : "not ");

        if (active != info->info.active)
        {
            if (active)
            {
                load_extension (manager, info);
            }
            else
            {
                unload_extension (manager, info);
            }
        }
    }

    g_slist_foreach (active_extensions, (GFunc) g_free, NULL);
    g_slist_free (active_extensions);

    if (value != NULL)
    {
        gconf_value_free (value);
    }
    g_object_unref (client);
}

static void
ephy_extensions_manager_unload_file (EphyExtensionsManager *manager,
                     const char *path)
{
    GList *l;
    ExtensionInfo *info;
    char *identifier;

    identifier = path_to_identifier (path);

    l = g_list_find_custom (manager->priv->data, identifier,
                (GCompareFunc) find_extension_info);

    if (l != NULL)
    {
        info = (ExtensionInfo *) l->data;

        manager->priv->data = g_list_remove (manager->priv->data, info);

        if (info->info.active == TRUE)
        {
            unload_extension (manager, info);
        }

        g_signal_emit (manager, signals[REMOVED], 0, info);

        free_extension_info (info);
    }

    g_free (identifier);
}

static void
load_file_from_monitor (EphyExtensionsManager *manager,
            const char *path)
{
    /* When a file is installed, it sometimes gets CREATED empty and then
     * gets its contents filled later (for a CHANGED signal). Theoretically
     * I suppose we could get a CHANGED signal when the file is half-full,
     * but I doubt that'll happen much (the xml files are <1000 bytes). We
     * don't want warnings all over the place, so we return from this
     * function if the file is empty. (We're assuming that if a file is
     * empty it'll be filled soon and this function will be called again.)
     *
     * Oh, and we return if the extension is already loaded, too.
     */
    char *identifier;
    char *xml;
    gsize len;
    GError *err = NULL;

    g_file_get_contents (path, &xml, &len, &err);

    if (err != NULL)
    {
        g_warning  ("Could not read file at '%s': '%s'",
                path, err->message);
        g_error_free (err);
        return;
    }

    if (len == 0) {
        g_free (xml);
        return;
    }

    identifier = path_to_identifier (path);
    g_return_if_fail (identifier != NULL);

    if (g_list_find_custom (manager->priv->data, identifier,
                (GCompareFunc) find_extension_info) != NULL)
    {
        g_free (identifier);
        g_free (xml);
        return;
    }

    ephy_extensions_manager_load_string (manager, identifier, xml);

    g_free (identifier);
    g_free (xml);

    sync_loaded_extensions (manager);
}

static void
dir_changed_cb (GnomeVFSMonitorHandle *handle,
        const char *monitor_uri,
        const char *info_uri,
        GnomeVFSMonitorEventType event_type,
        EphyExtensionsManager *manager)
{
    char *path;

    /*
     * We only deal with XML files: Add them to the manager when created,
     * remove them when deleted.
     */
    if (g_str_has_suffix (info_uri, ".xml") == FALSE) return;

    path = gnome_vfs_get_local_path_from_uri (info_uri);

    switch (event_type)
    {
        case GNOME_VFS_MONITOR_EVENT_CREATED:
        case GNOME_VFS_MONITOR_EVENT_CHANGED:
            load_file_from_monitor (manager, path);
            break;
        case GNOME_VFS_MONITOR_EVENT_DELETED:
            ephy_extensions_manager_unload_file (manager, path);
            break;
        default:
            break;
    }

    g_free (path);
}

static void
ephy_extensions_manager_load_dir (EphyExtensionsManager *manager,
                  const char *path)
{
    DIR *d;
    struct dirent *e;
    char *file_path;
    char *file_uri;
    GnomeVFSMonitorHandle *monitor;
    GnomeVFSResult res;

    LOG ("Scanning directory '%s'", path);

    START_PROFILER ("Scanning directory")

    d = opendir (path);
    if (d == NULL)
    {
        return;
    }
    while ((e = readdir (d)) != NULL)
    {
        if (g_str_has_suffix (e->d_name, ".xml"))
        {
            file_path = g_build_filename (path, e->d_name, NULL);
            ephy_extensions_manager_load_file (manager, file_path);
            g_free (file_path);
        }
    }
    closedir (d);

    file_uri = gnome_vfs_get_uri_from_local_path (path);
    res = gnome_vfs_monitor_add (&monitor,
                     path,
                     GNOME_VFS_MONITOR_DIRECTORY,
                     (GnomeVFSMonitorCallback) dir_changed_cb,
                     manager);
    g_free (file_uri);

    if (res == GNOME_VFS_OK)
    {
        manager->priv->dir_monitors = g_list_prepend
            (manager->priv->dir_monitors, monitor);
    }

    STOP_PROFILER ("Scanning directory")
}

static void
active_extensions_notifier (GConfClient *client,
                guint cnxn_id,
                GConfEntry *entry,
                EphyExtensionsManager *manager)
{
    sync_loaded_extensions (manager);
}

#ifdef ENABLE_VALIDATION
static void
xml_error_cb (EphyExtensionsManager *manager,
          const char *msg,
          ...)

{
    va_list args;

    va_start (args, msg);
    g_logv (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING, msg, args);
    va_end(args);
}

static void
init_schema_ctxt (EphyExtensionsManager *manager)
{
    xmlSchemaParserCtxtPtr parse_ctxt;
    const char *filename;

    manager->priv->schema = NULL;
    manager->priv->schema_ctxt = NULL;

    filename = ephy_file (SCHEMA_FILE);
    g_return_if_fail (filename != NULL);

    parse_ctxt = xmlSchemaNewParserCtxt (filename);
    if (parse_ctxt == NULL)
    {
        g_warning ("Error opening extensions description schema file "
               "\"" SCHEMA_FILE "\"");
        return;
    }

    manager->priv->schema = xmlSchemaParse (parse_ctxt);
    xmlSchemaFreeParserCtxt (parse_ctxt);
    if (manager->priv->schema == NULL)
    {
        g_warning ("Error parsing extensions description schema file "
               "\"" SCHEMA_FILE "\"");
        return;
    }

    manager->priv->schema_ctxt = xmlSchemaNewValidCtxt
        (manager->priv->schema);
    if (manager->priv->schema == NULL)
    {
        g_warning ("Error creating extensions description schema "
               "validation context for \"" SCHEMA_FILE "\"");
        return;
    }

    xmlSchemaSetValidErrors (manager->priv->schema_ctxt,
                 (xmlSchemaValidityErrorFunc) xml_error_cb,
                 (xmlSchemaValidityWarningFunc) xml_error_cb,
                 manager);
}
#endif

static void
ephy_extensions_manager_init (EphyExtensionsManager *manager)
{
    manager->priv = EPHY_EXTENSIONS_MANAGER_GET_PRIVATE (manager);

    LOG ("EphyExtensionsManager initialising");
}

void
ephy_extensions_manager_startup (EphyExtensionsManager *manager)
{
    char *path;

    g_return_if_fail (EPHY_IS_EXTENSIONS_MANAGER (manager));

    LOG ("EphyExtensionsManager startup");

#ifdef ENABLE_VALIDATION
    init_schema_ctxt (manager);
#endif

    /* load the extensions descriptions */
    path = g_build_filename (ephy_dot_dir (), "extensions", NULL);
    ephy_extensions_manager_load_dir (manager, path);
    g_free (path);

    ephy_extensions_manager_load_dir (manager, EXTENSIONS_DIR);

    active_extensions_notifier (NULL, 0, NULL, manager);
    manager->priv->active_extensions_notifier_id =
        eel_gconf_notification_add
            (CONF_LOADED_EXTENSIONS,
             (GConfClientNotifyFunc) active_extensions_notifier,
             manager);
}

static void
ephy_extensions_manager_finalize (GObject *object)
{
    EphyExtensionsManager *manager = EPHY_EXTENSIONS_MANAGER (object);
    EphyExtensionsManagerPrivate *priv = manager->priv;

    LOG ("EphyExtensionsManager finalising");

    eel_gconf_notification_remove (manager->priv->active_extensions_notifier_id);

    g_list_foreach (priv->dir_monitors, (GFunc) gnome_vfs_monitor_cancel, NULL);
    g_list_free (priv->dir_monitors);

    g_list_foreach (priv->extensions, (GFunc) g_object_unref, NULL);
    g_list_free (priv->extensions);

    /* FIXME release loaded loaders */
    g_list_foreach (priv->factories, (GFunc) free_loader_info, NULL);
    g_list_free (priv->factories);

    g_list_foreach (priv->data, (GFunc) free_extension_info, NULL);
    g_list_free (priv->data);

    g_list_free (priv->windows);

#ifdef ENABLE_VALIDATION
    if (priv->schema)
    {
        xmlSchemaFree (priv->schema);
    }
    if (priv->schema_ctxt)
    {
        xmlSchemaFreeValidCtxt (priv->schema_ctxt);
    }
#endif

    parent_class->finalize (object);
}

static void
attach_extension_to_window (EphyExtension *extension,
                EphyWindow *window)
{
    attach_window (window, extension);
}

static void
impl_attach_window (EphyExtension *extension,
            EphyWindow *window)
{
    EphyExtensionsManager *manager = EPHY_EXTENSIONS_MANAGER (extension);

    LOG ("Attach window %p", window);

    g_list_foreach (manager->priv->extensions,
            (GFunc) attach_extension_to_window, window);

    manager->priv->windows = g_list_prepend (manager->priv->windows, window);
}

static void
impl_detach_window (EphyExtension *extension,
            EphyWindow *window)
{
    EphyExtensionsManager *manager = EPHY_EXTENSIONS_MANAGER (extension);
    GList *tabs, *l;

    LOG ("Detach window %p", window);

    manager->priv->windows = g_list_remove (manager->priv->windows, window);

    g_object_ref (window);

    /* Detach tabs (uses impl_detach_tab) */
    tabs = ephy_window_get_tabs (window);
    for (l = tabs; l; l = l->next)
    {
        ephy_extension_detach_tab (extension, window,
                       EPHY_TAB (l->data));
    }
    g_list_free (tabs);

    /* Then detach the window */
    g_list_foreach (manager->priv->extensions,
            (GFunc) ephy_extension_detach_window, window);

    g_object_unref (window);
}

static void
impl_attach_tab (EphyExtension *extension,
         EphyWindow *window,
         EphyTab *tab)
{
    EphyExtensionsManager *manager = EPHY_EXTENSIONS_MANAGER (extension);
    GList *l;

    LOG ("Attach window %p tab %p", window, tab);

    for (l = manager->priv->extensions; l; l = l->next)
    {
        ephy_extension_attach_tab (EPHY_EXTENSION (l->data),
                       window, tab);
    }
}

static void
impl_detach_tab (EphyExtension *extension,
         EphyWindow *window,
         EphyTab *tab)
{
    EphyExtensionsManager *manager = EPHY_EXTENSIONS_MANAGER (extension);
    GList *l;

    LOG ("Detach window %p tab %p", window, tab);

    g_object_ref (window);
    g_object_ref (tab);

    for (l = manager->priv->extensions; l; l = l->next)
    {
        ephy_extension_detach_tab (EPHY_EXTENSION (l->data),
                       window, tab);
    }

    g_object_unref (tab);
    g_object_unref (window);
}

static void
ephy_extensions_manager_iface_init (EphyExtensionIface *iface)
{
    iface->attach_window = impl_attach_window;
    iface->detach_window = impl_detach_window;
    iface->attach_tab    = impl_attach_tab;
    iface->detach_tab    = impl_detach_tab;
}

static void
ephy_extensions_manager_class_init (EphyExtensionsManagerClass *class)
{
    GObjectClass *object_class = G_OBJECT_CLASS (class);

    parent_class = (GObjectClass *) g_type_class_peek_parent (class);

    object_class->finalize = ephy_extensions_manager_finalize;

    signals[CHANGED] =
        g_signal_new ("changed",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_FIRST,
                  G_STRUCT_OFFSET (EphyExtensionsManagerClass, changed),
                  NULL, NULL,
                  g_cclosure_marshal_VOID__POINTER,
                  G_TYPE_NONE,
                  1,
                  G_TYPE_POINTER);
    signals[ADDED] =
        g_signal_new ("added",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_FIRST,
                  G_STRUCT_OFFSET (EphyExtensionsManagerClass, added),
                  NULL, NULL,
                  g_cclosure_marshal_VOID__POINTER,
                  G_TYPE_NONE,
                  1,
                  G_TYPE_POINTER);
    signals[REMOVED] =
        g_signal_new ("removed",
                  G_OBJECT_CLASS_TYPE (object_class),
                  G_SIGNAL_RUN_FIRST,
                  G_STRUCT_OFFSET (EphyExtensionsManagerClass, removed),
                  NULL, NULL,
                  g_cclosure_marshal_VOID__POINTER,
                  G_TYPE_NONE,
                  1,
                  G_TYPE_POINTER);
    
    g_type_class_add_private (object_class, sizeof (EphyExtensionsManagerPrivate));

    languages = g_get_language_names ();
    g_assert (languages != NULL);
}