path: root/camel/camel-provider.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* camel-provider.c :  provider framework   */

/* 
 *
 * Author : 
 *  Bertrand Guiheneuf <bertrand@helixcode.com>
 *
 * Copyright 1999, 2000 Helix Code, Inc. (http://www.helixcode.com)
 *
 * 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 of the
 * License, 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
 */


/* 
   A provider can be added "by hand" or by loading a module. 


   Adding providers with modules. 
   ------------------------------

   The modules are shared libraries which must contain the 
   function

   CamelProvider *camel_provider_module_init ();
  
   returning the provider object defined in the module 

   
*/

/* FIXME: Shouldn't we add a version number to providers ? */

#include "config.h"
#include "camel-provider.h"

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

static GList *_provider_list = NULL;

static gint        
_provider_name_cmp (gconstpointer a, gconstpointer b)
{
    CamelProvider *provider_a = CAMEL_PROVIDER (a);
    CamelProvider *provider_b = CAMEL_PROVIDER (b);

    return strcmp ( provider_a->name,  provider_b->name);
}

void
camel_provider_register (CamelProvider *provider)
{
    GList *old_provider_node = NULL;

    g_assert (provider);

    if (_provider_list)
        old_provider_node = g_list_find_custom (_provider_list, provider, _provider_name_cmp);

    if (old_provider_node != NULL) {
        /* camel_provider_unref (CAMEL_PROVIDER (old_provider_node->data)); */
        old_provider_node->data = provider;
    } else {
        /* be careful, we use prepend here, so that last registered
           providers come first */
        _provider_list = g_list_prepend (_provider_list, provider);
    }
    /* camel_provider_ref (provider); */
}


const CamelProvider *
camel_provider_register_as_module (const gchar *module_path)
{
    
    CamelProvider *new_provider = NULL;
    GModule *new_module = NULL;
    CamelProvider * (*camel_provider_module_init) ();
    gboolean has_module_init;
    
    g_return_val_if_fail (module_path, NULL);

    if (!g_module_supported ()) {
        g_warning ("CamelProvider::register_as_module: module "
               "loading not supported on this system\n");
        return NULL;
    }
    

    new_module = g_module_open (module_path, 0);
    if (!new_module) {
        printf ("g_module_open reports: %s\n", g_module_error ());
        g_warning ("CamelProvider::register_as_module: Unable to "
               "load module %s\n", module_path);
        return NULL;
    }
        
    has_module_init = g_module_symbol (new_module, "camel_provider_module_init", (gpointer *)&camel_provider_module_init);
    if (!has_module_init){
        g_warning ("CamelProvider::register_as_module loading "
               "of module %s failed,\n\tSymbol "
               "camel_provider_module_init not defined in it\n",
               module_path);
        return NULL;
    }

    new_provider = camel_provider_module_init();
    new_provider->gmodule = new_module;
    camel_provider_register (new_provider);

    return new_provider;
} 

/**
 * camel_provider_scan: Scan for available providers and return a list.
 *
 * Note that this function will cause all providers in the providerdir
 * to be loaded into memory.
 *
 * Return value: the list of CamelProviders. The caller must free this
 * list when it is done with it.
 **/
GList *
camel_provider_scan (void)
{
    DIR *dir;
    struct dirent *dent;
    char *p, *name;

    dir = opendir (CAMEL_PROVIDERDIR);
    if (!dir)
        return NULL;
    while ((dent = readdir (dir))) {
        p = strstr (dent->d_name, ".so");
        if (!p || strcmp (p, ".so") != 0)
            continue;

        name = g_module_build_path (CAMEL_PROVIDERDIR, dent->d_name);
        camel_provider_register_as_module (name);
        g_free (name);
    }
    closedir (dir);

    return g_list_copy (_provider_list);
}
    

/**
 * camel_provider_get_for_protocol: get a registered provider for a protocol
 * @protocol: protocol name (case insensitive)
 * @type: provider type (transport, store, ...)
 * 
 * Look into the list of registered provider if 
 * one correspond both to the protocol name 
 * and to the protocol type. When several providers
 * exist for a same protocol, the last registered
 * is returned.
 * 
 * Return value: Matching provider or NULL if none exists. 
 **/
const CamelProvider *
camel_provider_get_for_protocol (const gchar *protocol, ProviderType type)
{
    CamelProvider *current_provider = NULL;
    GList *current_provider_node;
    gboolean protocol_is_found;
    gboolean provider_is_found;

    g_assert (protocol);
    g_return_val_if_fail (_provider_list, NULL);

    current_provider_node = _provider_list;
    provider_is_found = FALSE;

    while ((!provider_is_found) && current_provider_node) {
        current_provider = (CamelProvider *)current_provider_node->data;
        
        protocol_is_found = (g_strcasecmp (protocol, current_provider->protocol) == 0);
        if (protocol_is_found) 
            provider_is_found = (current_provider->provider_type == type);
        
        current_provider_node = current_provider_node->next;
        }

    if (provider_is_found) return current_provider;
    else return NULL;
}