// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * item.c - library routines for handling generic config items
   *

   * 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.rst 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.
   */

  static 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.

   *	@fmt:  The vsnprintf()'s format string.

   *
   *	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 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 {

  		va_start(args, fmt);

  		name = kvasprintf(GFP_KERNEL, fmt, args);

  		va_end(args);

  		if (!name)
  			return -EFAULT;

  	}
  
  	/* 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;

  	return 0;

  }

  EXPORT_SYMBOL(config_item_set_name);
  
  void config_item_init_type_name(struct config_item *item,
  				const char *name,

  				const struct config_item_type *type)

  {

  	config_item_set_name(item, "%s", 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,

  			 const struct config_item_type *type)

  {

  	config_item_set_name(&group->cg_item, "%s", 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;
  }

  EXPORT_SYMBOL(config_item_get);

  struct config_item *config_item_get_unless_zero(struct config_item *item)
  {
  	if (item && kref_get_unless_zero(&item->ci_kref))
  		return item;
  	return NULL;
  }
  EXPORT_SYMBOL(config_item_get_unless_zero);

  static void config_item_cleanup(struct config_item *item)

  {

  	const 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);
  }

  EXPORT_SYMBOL(config_item_put);

  /**
   *	config_group_init - initialize a group for use

   *	@group:	config_group

   */

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

  	INIT_LIST_HEAD(&group->default_groups);

  }

  EXPORT_SYMBOL(config_group_init);

  /**

   *	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_group_find_item);