/*
   * fs/sysfs/group.c - Operations for adding/removing multiple files at once.
   *
   * Copyright (c) 2003 Patrick Mochel
   * Copyright (c) 2003 Open Source Development Lab

   * Copyright (c) 2013 Greg Kroah-Hartman
   * Copyright (c) 2013 The Linux Foundation

   *

   * 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 kernfs_node *parent,

  			 const struct attribute_group *grp)

  {

  	struct attribute *const *attr;
  	struct bin_attribute *const *bin_attr;

  	if (grp->attrs)
  		for (attr = grp->attrs; *attr; attr++)

  			kernfs_remove_by_name(parent, (*attr)->name);

  	if (grp->bin_attrs)
  		for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++)

  			kernfs_remove_by_name(parent, (*bin_attr)->attr.name);

  }

  static int create_files(struct kernfs_node *parent, struct kobject *kobj,

  			const struct attribute_group *grp, int update)

  {

  	struct attribute *const *attr;
  	struct bin_attribute *const *bin_attr;

  	int error = 0, i;

  	if (grp->attrs) {
  		for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {

  			umode_t mode = (*attr)->mode;

  			/*
  			 * In update mode, we're changing the permissions or
  			 * visibility.  Do this by first removing then
  			 * re-adding (if required) the file.
  			 */
  			if (update)

  				kernfs_remove_by_name(parent, (*attr)->name);

  			if (grp->is_visible) {
  				mode = grp->is_visible(kobj, *attr, i);
  				if (!mode)
  					continue;
  			}

  
  			WARN(mode & ~(SYSFS_PREALLOC | 0664),
  			     "Attribute %s: Invalid permissions 0%o
  ",
  			     (*attr)->name, mode);
  
  			mode &= SYSFS_PREALLOC | 0664;

  			error = sysfs_add_file_mode_ns(parent, *attr, false,

  						       mode, NULL);

  			if (unlikely(error))
  				break;
  		}
  		if (error) {

  			remove_files(parent, grp);

  			goto exit;
  		}
  	}
  
  	if (grp->bin_attrs) {

  		for (i = 0, bin_attr = grp->bin_attrs; *bin_attr; i++, bin_attr++) {
  			umode_t mode = (*bin_attr)->attr.mode;

  			if (update)

  				kernfs_remove_by_name(parent,
  						(*bin_attr)->attr.name);

  			if (grp->is_bin_visible) {
  				mode = grp->is_bin_visible(kobj, *bin_attr, i);
  				if (!mode)
  					continue;
  			}
  
  			WARN(mode & ~(SYSFS_PREALLOC | 0664),
  			     "Attribute %s: Invalid permissions 0%o
  ",
  			     (*bin_attr)->attr.name, mode);
  
  			mode &= SYSFS_PREALLOC | 0664;

  			error = sysfs_add_file_mode_ns(parent,
  					&(*bin_attr)->attr, true,

  					mode, NULL);

  			if (error)
  				break;

  		}

  		if (error)

  			remove_files(parent, grp);

  	}

  exit:

  	return error;
  }

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

  {

  	struct kernfs_node *kn;

  	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->attrs && !grp->bin_attrs) {
  		WARN(1, "sysfs: (bin_)attrs not set by subsystem for group: %s/%s
  ",

  			kobj->name, grp->name ?: "");

  		return -EINVAL;
  	}

  	if (grp->name) {

  		kn = kernfs_create_dir(kobj->sd, grp->name,
  				       S_IRWXU | S_IRUGO | S_IXUGO, kobj);

  		if (IS_ERR(kn)) {
  			if (PTR_ERR(kn) == -EEXIST)

  				sysfs_warn_dup(kobj->sd, grp->name);

  			return PTR_ERR(kn);

  		}

  	} else

  		kn = kobj->sd;
  	kernfs_get(kn);
  	error = create_files(kn, kobj, grp, update);

  	if (error) {

  		if (grp->name)

  			kernfs_remove(kn);

  	}

  	kernfs_put(kn);

  	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 code on failure.

   */
  int sysfs_create_group(struct kobject *kobj,
  		       const struct attribute_group *grp)
  {
  	return internal_create_group(kobj, 0, grp);
  }

  EXPORT_SYMBOL_GPL(sysfs_create_group);

  
  /**

   * sysfs_create_groups - given a directory kobject, create a bunch of attribute groups
   * @kobj:	The kobject to create the group on
   * @groups:	The attribute groups to create, NULL terminated
   *
   * This function creates a bunch of attribute groups.  If an error occurs when
   * creating a group, all previously created groups will be removed, unwinding
   * everything back to the original state when this function was called.
   * It will explicitly warn and error if any of the attribute files being
   * created already exist.
   *

   * Returns 0 on success or error code from sysfs_create_group on failure.

   */
  int sysfs_create_groups(struct kobject *kobj,
  			const struct attribute_group **groups)
  {
  	int error = 0;
  	int i;
  
  	if (!groups)
  		return 0;
  
  	for (i = 0; groups[i]; i++) {
  		error = sysfs_create_group(kobj, groups[i]);
  		if (error) {
  			while (--i >= 0)
  				sysfs_remove_group(kobj, groups[i]);
  			break;
  		}
  	}
  	return error;
  }
  EXPORT_SYMBOL_GPL(sysfs_create_groups);
  
  /**

   * 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 code on failure.

   */
  int sysfs_update_group(struct kobject *kobj,
  		       const struct attribute_group *grp)
  {
  	return internal_create_group(kobj, 1, grp);
  }

  EXPORT_SYMBOL_GPL(sysfs_update_group);

  /**
   * sysfs_remove_group: remove a group from a kobject
   * @kobj:	kobject to remove the group from
   * @grp:	group to remove
   *
   * This function removes a group of attributes from a kobject.  The attributes
   * previously have to have been created for this group, otherwise it will fail.
   */

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

  {

  	struct kernfs_node *parent = kobj->sd;
  	struct kernfs_node *kn;

  	if (grp->name) {

  		kn = kernfs_find_and_get(parent, grp->name);
  		if (!kn) {
  			WARN(!kn, KERN_WARNING

  			     "sysfs group '%s' not found for kobject '%s'
  ",
  			     grp->name, kobject_name(kobj));

  			return;
  		}

  	} else {

  		kn = parent;
  		kernfs_get(kn);

  	}

  	remove_files(kn, grp);

  	if (grp->name)

  		kernfs_remove(kn);

  	kernfs_put(kn);

  }

  EXPORT_SYMBOL_GPL(sysfs_remove_group);

  /**

   * sysfs_remove_groups - remove a list of groups
   *

   * @kobj:	The kobject for the groups to be removed from
   * @groups:	NULL terminated list of groups to be removed

   *

   * If groups is not NULL, remove the specified groups from the kobject.

   */
  void sysfs_remove_groups(struct kobject *kobj,
  			 const struct attribute_group **groups)
  {
  	int i;
  
  	if (!groups)
  		return;
  	for (i = 0; groups[i]; i++)
  		sysfs_remove_group(kobj, groups[i]);
  }
  EXPORT_SYMBOL_GPL(sysfs_remove_groups);
  
  /**

   * 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 kernfs_node *parent;

  	int error = 0;
  	struct attribute *const *attr;
  	int i;

  	parent = kernfs_find_and_get(kobj->sd, grp->name);
  	if (!parent)

  		return -ENOENT;
  
  	for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))

  		error = sysfs_add_file(parent, *attr, false);

  	if (error) {
  		while (--i >= 0)

  			kernfs_remove_by_name(parent, (*--attr)->name);

  	}

  	kernfs_put(parent);

  
  	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 kernfs_node *parent;

  	struct attribute *const *attr;

  	parent = kernfs_find_and_get(kobj->sd, grp->name);
  	if (parent) {

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

  			kernfs_remove_by_name(parent, (*attr)->name);
  		kernfs_put(parent);

  	}
  }
  EXPORT_SYMBOL_GPL(sysfs_unmerge_group);

  /**
   * sysfs_add_link_to_group - add a symlink to an attribute group.
   * @kobj:	The kobject containing the group.
   * @group_name:	The name of the group.
   * @target:	The target kobject of the symlink to create.
   * @link_name:	The name of the symlink to create.
   */
  int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
  			    struct kobject *target, const char *link_name)
  {

  	struct kernfs_node *parent;

  	int error = 0;

  	parent = kernfs_find_and_get(kobj->sd, group_name);
  	if (!parent)

  		return -ENOENT;

  	error = sysfs_create_link_sd(parent, target, link_name);
  	kernfs_put(parent);

  
  	return error;
  }
  EXPORT_SYMBOL_GPL(sysfs_add_link_to_group);
  
  /**
   * sysfs_remove_link_from_group - remove a symlink from an attribute group.
   * @kobj:	The kobject containing the group.
   * @group_name:	The name of the group.
   * @link_name:	The name of the symlink to remove.
   */
  void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
  				  const char *link_name)
  {

  	struct kernfs_node *parent;

  	parent = kernfs_find_and_get(kobj->sd, group_name);
  	if (parent) {
  		kernfs_remove_by_name(parent, link_name);
  		kernfs_put(parent);

  	}
  }
  EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);

  
  /**
   * __compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
   * to a group or an attribute
   * @kobj:		The kobject containing the group.
   * @target_kobj:	The target kobject.
   * @target_name:	The name of the target group or attribute.
   */
  int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
  				      struct kobject *target_kobj,
  				      const char *target_name)
  {
  	struct kernfs_node *target;
  	struct kernfs_node *entry;
  	struct kernfs_node *link;
  
  	/*
  	 * We don't own @target_kobj and it may be removed at any time.
  	 * Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
  	 * for details.
  	 */
  	spin_lock(&sysfs_symlink_target_lock);
  	target = target_kobj->sd;
  	if (target)
  		kernfs_get(target);
  	spin_unlock(&sysfs_symlink_target_lock);
  	if (!target)
  		return -ENOENT;
  
  	entry = kernfs_find_and_get(target_kobj->sd, target_name);
  	if (!entry) {
  		kernfs_put(target);
  		return -ENOENT;
  	}
  
  	link = kernfs_create_link(kobj->sd, target_name, entry);
  	if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
  		sysfs_warn_dup(kobj->sd, target_name);
  
  	kernfs_put(entry);
  	kernfs_put(target);
  	return IS_ERR(link) ? PTR_ERR(link) : 0;
  }
  EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);