item.c

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/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * item.c - library routines for handling generic config items
 *
 * 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 021110-1307, USA.
 *
 * Based on kobject:
 *  kobject is Copyright (c) 2002-2003 Patrick Mochel
 *
 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
 *
 * Please see the file Documentation/filesystems/configfs/configfs.txt for
 * critical information about using the config_item interface.
 */

#include <linux/string.h>
#include <linux/module.h>
#include <linux/stat.h>
#include <linux/slab.h>

#include <linux/configfs.h>


static inline struct config_item * to_item(struct list_head * entry)
{
    return container_of(entry,struct config_item,ci_entry);
}

/* Evil kernel */
static void config_item_release(struct kref *kref);

void config_item_init(struct config_item * item)
{
    kref_init(&item->ci_kref);
    INIT_LIST_HEAD(&item->ci_entry);
}

int config_item_set_name(struct config_item * item, const char * fmt, ...)
{
    int error = 0;
    int limit = CONFIGFS_ITEM_NAME_LEN;
    int need;
    va_list args;
    char * name;

    /*
     * First, try the static array
     */
    va_start(args,fmt);
    need = vsnprintf(item->ci_namebuf,limit,fmt,args);
    va_end(args);
    if (need < limit)
        name = item->ci_namebuf;
    else {
        /*
         * Need more space? Allocate it and try again
         */
        limit = need + 1;
        name = kmalloc(limit,GFP_KERNEL);
        if (!name) {
            error = -ENOMEM;
            goto Done;
        }
        va_start(args,fmt);
        need = vsnprintf(name,limit,fmt,args);
        va_end(args);

        /* Still? Give up. */
        if (need >= limit) {
            kfree(name);
            error = -EFAULT;
            goto Done;
        }
    }

    /* Free the old name, if necessary. */
    if (item->ci_name && item->ci_name != item->ci_namebuf)
        kfree(item->ci_name);

    /* Now, set the new name */
    item->ci_name = name;
 Done:
    return error;
}

EXPORT_SYMBOL(config_item_set_name);

void config_item_init_type_name(struct config_item *item,
                const char *name,
                struct config_item_type *type)
{
    config_item_set_name(item, name);
    item->ci_type = type;
    config_item_init(item);
}
EXPORT_SYMBOL(config_item_init_type_name);

void config_group_init_type_name(struct config_group *group, const char *name,
             struct config_item_type *type)
{
    config_item_set_name(&group->cg_item, name);
    group->cg_item.ci_type = type;
    config_group_init(group);
}
EXPORT_SYMBOL(config_group_init_type_name);

struct config_item * config_item_get(struct config_item * item)
{
    if (item)
        kref_get(&item->ci_kref);
    return item;
}

static void config_item_cleanup(struct config_item * item)
{
    struct config_item_type * t = item->ci_type;
    struct config_group * s = item->ci_group;
    struct config_item * parent = item->ci_parent;

    pr_debug("config_item %s: cleaning up\n",config_item_name(item));
    if (item->ci_name != item->ci_namebuf)
        kfree(item->ci_name);
    item->ci_name = NULL;
    if (t && t->ct_item_ops && t->ct_item_ops->release)
        t->ct_item_ops->release(item);
    if (s)
        config_group_put(s);
    if (parent)
        config_item_put(parent);
}

static void config_item_release(struct kref *kref)
{
    config_item_cleanup(container_of(kref, struct config_item, ci_kref));
}

void config_item_put(struct config_item * item)
{
    if (item)
        kref_put(&item->ci_kref, config_item_release);
}

void config_group_init(struct config_group *group)
{
    config_item_init(&group->cg_item);
    INIT_LIST_HEAD(&group->cg_children);
}

struct config_item *config_group_find_item(struct config_group *group,
                       const char *name)
{
    struct list_head * entry;
    struct config_item * ret = NULL;

    list_for_each(entry,&group->cg_children) {
        struct config_item * item = to_item(entry);
        if (config_item_name(item) &&
            !strcmp(config_item_name(item), name)) {
            ret = config_item_get(item);
            break;
        }
    }
    return ret;
}

EXPORT_SYMBOL(config_item_init);
EXPORT_SYMBOL(config_group_init);
EXPORT_SYMBOL(config_item_get);
EXPORT_SYMBOL(config_item_put);
EXPORT_SYMBOL(config_group_find_item);