/*
   * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
   *
   * Copyright (c) 2003 Patrick Mochel
   * Copyright (c) 2003 Open Source Development Lab
   *
   * This file is released undert the GPL v2. 
   *
   */
  
  #include <linux/kobject.h>
  #include <linux/module.h>
  #include <linux/dcache.h>

  #include <linux/namei.h>

  #include <linux/err.h>
  #include "sysfs.h"

  static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,

  			 const struct attribute_group *grp)

  {
  	struct attribute *const* attr;

  	int i;

  	for (i = 0, attr = grp->attrs; *attr; i++, attr++)

  		sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);

  }

  static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,

  			const struct attribute_group *grp, int update)

  {
  	struct attribute *const* attr;

  	int error = 0, i;

  	for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
  		mode_t mode = 0;
  
  		/* in update mode, we're changing the permissions or
  		 * visibility.  Do this by first removing then
  		 * re-adding (if required) the file */
  		if (update)

  			sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);

  		if (grp->is_visible) {
  			mode = grp->is_visible(kobj, *attr, i);
  			if (!mode)
  				continue;
  		}
  		error = sysfs_add_file_mode(dir_sd, *attr, SYSFS_KOBJ_ATTR,
  					    (*attr)->mode | mode);
  		if (unlikely(error))
  			break;
  	}

  	if (error)

  		remove_files(dir_sd, kobj, grp);

  	return error;
  }

  static int internal_create_group(struct kobject *kobj, int update,
  				 const struct attribute_group *grp)

  {

  	struct sysfs_dirent *sd;

  	int error;

  	BUG_ON(!kobj || (!update && !kobj->sd));
  
  	/* Updates may happen before the object has been instantiated */
  	if (unlikely(update && !kobj->sd))
  		return -EINVAL;

  
  	if (grp->name) {

  		error = sysfs_create_subdir(kobj, grp->name, &sd);

  		if (error)
  			return error;
  	} else

  		sd = kobj->sd;
  	sysfs_get(sd);

  	error = create_files(sd, kobj, grp, update);

  	if (error) {

  		if (grp->name)

  			sysfs_remove_subdir(sd);

  	}

  	sysfs_put(sd);

  	return error;
  }

  /**
   * sysfs_create_group - given a directory kobject, create an attribute group
   * @kobj:	The kobject to create the group on
   * @grp:	The attribute group to create
   *
   * This function creates a group for the first time.  It will explicitly
   * warn and error if any of the attribute files being created already exist.
   *
   * Returns 0 on success or error.
   */
  int sysfs_create_group(struct kobject *kobj,
  		       const struct attribute_group *grp)
  {
  	return internal_create_group(kobj, 0, grp);
  }
  
  /**

   * sysfs_update_group - given a directory kobject, update an attribute group
   * @kobj:	The kobject to update the group on
   * @grp:	The attribute group to update

   *
   * This function updates an attribute group.  Unlike
   * sysfs_create_group(), it will explicitly not warn or error if any
   * of the attribute files being created already exist.  Furthermore,
   * if the visibility of the files has changed through the is_visible()
   * callback, it will update the permissions and add or remove the
   * relevant files.
   *
   * The primary use for this function is to call it after making a change
   * that affects group visibility.
   *
   * Returns 0 on success or error.
   */
  int sysfs_update_group(struct kobject *kobj,
  		       const struct attribute_group *grp)
  {
  	return internal_create_group(kobj, 1, grp);
  }

  void sysfs_remove_group(struct kobject * kobj, 
  			const struct attribute_group * grp)
  {

  	struct sysfs_dirent *dir_sd = kobj->sd;
  	struct sysfs_dirent *sd;

  	if (grp->name) {

  		sd = sysfs_get_dirent(dir_sd, NULL, grp->name);

  		if (!sd) {

  			WARN(!sd, KERN_WARNING "sysfs group %p not found for "

  				"kobject '%s'
  ", grp, kobject_name(kobj));

  			return;
  		}

  	} else
  		sd = sysfs_get(dir_sd);

  	remove_files(sd, kobj, grp);

  	if (grp->name)

  		sysfs_remove_subdir(sd);
  
  	sysfs_put(sd);

  }

  /**
   * sysfs_merge_group - merge files into a pre-existing attribute group.
   * @kobj:	The kobject containing the group.
   * @grp:	The files to create and the attribute group they belong to.
   *
   * This function returns an error if the group doesn't exist or any of the
   * files already exist in that group, in which case none of the new files
   * are created.
   */
  int sysfs_merge_group(struct kobject *kobj,
  		       const struct attribute_group *grp)
  {
  	struct sysfs_dirent *dir_sd;
  	int error = 0;
  	struct attribute *const *attr;
  	int i;

  	dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);

  	if (!dir_sd)
  		return -ENOENT;
  
  	for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
  		error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
  	if (error) {
  		while (--i >= 0)
  			sysfs_hash_and_remove(dir_sd, NULL, (*--attr)->name);
  	}
  	sysfs_put(dir_sd);
  
  	return error;
  }
  EXPORT_SYMBOL_GPL(sysfs_merge_group);
  
  /**
   * sysfs_unmerge_group - remove files from a pre-existing attribute group.
   * @kobj:	The kobject containing the group.
   * @grp:	The files to remove and the attribute group they belong to.
   */
  void sysfs_unmerge_group(struct kobject *kobj,
  		       const struct attribute_group *grp)
  {
  	struct sysfs_dirent *dir_sd;
  	struct attribute *const *attr;

  	dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);

  	if (dir_sd) {
  		for (attr = grp->attrs; *attr; ++attr)
  			sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);
  		sysfs_put(dir_sd);
  	}
  }
  EXPORT_SYMBOL_GPL(sysfs_unmerge_group);

  
  EXPORT_SYMBOL_GPL(sysfs_create_group);

  EXPORT_SYMBOL_GPL(sysfs_update_group);

  EXPORT_SYMBOL_GPL(sysfs_remove_group);