/* -*- 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);
  
  /**
   *	config_item_init - initialize item.
   *	@item:	item in question.
   */
  void config_item_init(struct config_item * item)
  {
  	kref_init(&item->ci_kref);
  	INIT_LIST_HEAD(&item->ci_entry);
  }
  
  /**
   *	config_item_set_name - Set the name of an item
   *	@item:	item.
   *	@name:	name.
   *
   *	If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a
   *	dynamically allocated string that @item->ci_name points to.
   *	Otherwise, use the static @item->ci_namebuf array.
   */
  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
  ",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));
  }
  
  /**
   *	config_item_put - decrement refcount for item.
   *	@item:	item.
   *
   *	Decrement the refcount, and if 0, call config_item_cleanup().
   */
  void config_item_put(struct config_item * item)
  {
  	if (item)
  		kref_put(&item->ci_kref, config_item_release);
  }
  
  /**
   *	config_group_init - initialize a group for use
   *	@k:	group
   */
  void config_group_init(struct config_group *group)
  {
  	config_item_init(&group->cg_item);
  	INIT_LIST_HEAD(&group->cg_children);
  }
  
  /**
   *	config_group_find_item - search for item in group.
   *	@group:	group we're looking in.
   *	@name:	item's name.
   *
   *	Iterate over @group->cg_list, looking for a matching config_item.
   *	If matching item is found take a reference and return the item.
   *	Caller must have locked group via @group->cg_subsys->su_mtx.
   */
  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);