/*

   * fs/sysfs/file.c - sysfs regular (text) file implementation
   *
   * Copyright (c) 2001-3 Patrick Mochel
   * Copyright (c) 2007 SUSE Linux Products GmbH
   * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
   *
   * This file is released under the GPLv2.
   *
   * Please see Documentation/filesystems/sysfs.txt for more information.

   */
  
  #include <linux/module.h>

  #include <linux/kobject.h>

  #include <linux/kallsyms.h>

  #include <linux/slab.h>

  #include <linux/list.h>

  #include <linux/mutex.h>

  #include <linux/seq_file.h>

  
  #include "sysfs.h"

  #include "../kernfs/kernfs-internal.h"

  
  /*

   * Determine ktype->sysfs_ops for the given kernfs_node.  This function

   * must be called while holding an active reference.
   */

  static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)

  {

  	struct kobject *kobj = kn->parent->priv;

  	if (kn->flags & KERNFS_LOCKDEP)

  		lockdep_assert_held(kn);

  	return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
  }

  /*
   * Reads on sysfs are handled through seq_file, which takes care of hairy
   * details like buffering and seeking.  The following function pipes
   * sysfs_ops->show() result through seq_file.

   */

  static int sysfs_kf_seq_show(struct seq_file *sf, void *v)

  {

  	struct kernfs_open_file *of = sf->private;

  	struct kobject *kobj = of->kn->parent->priv;

  	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);

  	ssize_t count;

  	char *buf;

  	/* acquire buffer and ensure that it's >= PAGE_SIZE and clear */

  	count = seq_get_buf(sf, &buf);
  	if (count < PAGE_SIZE) {
  		seq_commit(sf, -1);
  		return 0;
  	}

  	memset(buf, 0, PAGE_SIZE);

  	/*

  	 * Invoke show().  Control may reach here via seq file lseek even
  	 * if @ops->show() isn't implemented.

  	 */

  	if (ops->show) {

  		count = ops->show(kobj, of->kn->priv, buf);

  		if (count < 0)
  			return count;
  	}

  	/*
  	 * The code works fine with PAGE_SIZE return but it's likely to
  	 * indicate truncated result or overflow in normal use cases.
  	 */

  	if (count >= (ssize_t)PAGE_SIZE) {
  		print_symbol("fill_read_buffer: %s returned bad count
  ",
  			(unsigned long)ops->show);
  		/* Try to struggle along */
  		count = PAGE_SIZE - 1;
  	}

  	seq_commit(sf, count);
  	return 0;

  }

  static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,

  				 size_t count, loff_t pos)

  {

  	struct bin_attribute *battr = of->kn->priv;

  	struct kobject *kobj = of->kn->parent->priv;

  	loff_t size = file_inode(of->file)->i_size;

  	if (!count)

  		return 0;
  
  	if (size) {

  		if (pos >= size)

  			return 0;

  		if (pos + count > size)
  			count = size - pos;

  	}

  	if (!battr->read)
  		return -EIO;
  
  	return battr->read(of->file, kobj, battr, buf, pos, count);
  }

  /* kernfs read callback for regular sysfs files with pre-alloc */
  static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
  			     size_t count, loff_t pos)
  {
  	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
  	struct kobject *kobj = of->kn->parent->priv;

  	ssize_t len;

  
  	/*
  	 * If buf != of->prealloc_buf, we don't know how
  	 * large it is, so cannot safely pass it to ->show
  	 */

  	if (WARN_ON_ONCE(buf != of->prealloc_buf))

  		return 0;

  	len = ops->show(kobj, of->kn->priv, buf);

  	if (len < 0)
  		return len;

  	if (pos) {
  		if (len <= pos)
  			return 0;
  		len -= pos;
  		memmove(buf, buf + pos, len);
  	}

  	return min_t(ssize_t, count, len);

  }

  /* kernfs write callback for regular sysfs files */

  static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,

  			      size_t count, loff_t pos)

  {

  	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);

  	struct kobject *kobj = of->kn->parent->priv;

  	if (!count)
  		return 0;

  	return ops->store(kobj, of->kn->priv, buf, count);

  }

  /* kernfs write callback for bin sysfs files */

  static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,

  				  size_t count, loff_t pos)
  {

  	struct bin_attribute *battr = of->kn->priv;

  	struct kobject *kobj = of->kn->parent->priv;

  	loff_t size = file_inode(of->file)->i_size;

  	if (size) {
  		if (size <= pos)

  			return -EFBIG;

  		count = min_t(ssize_t, count, size - pos);

  	}

  	if (!count)
  		return 0;

  	if (!battr->write)
  		return -EIO;

  	return battr->write(of->file, kobj, battr, buf, pos, count);

  }

  static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,

  			     struct vm_area_struct *vma)
  {

  	struct bin_attribute *battr = of->kn->priv;

  	struct kobject *kobj = of->kn->parent->priv;

  	return battr->mmap(of->file, kobj, battr, vma);
  }

  void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)

  {

  	struct kernfs_node *kn = kobj->sd, *tmp;

  	if (kn && dir)
  		kn = kernfs_find_and_get(kn, dir);

  	else

  		kernfs_get(kn);

  	if (kn && attr) {
  		tmp = kernfs_find_and_get(kn, attr);
  		kernfs_put(kn);
  		kn = tmp;

  	}

  	if (kn) {
  		kernfs_notify(kn);
  		kernfs_put(kn);

  	}

  }
  EXPORT_SYMBOL_GPL(sysfs_notify);

  static const struct kernfs_ops sysfs_file_kfops_empty = {
  };
  
  static const struct kernfs_ops sysfs_file_kfops_ro = {
  	.seq_show	= sysfs_kf_seq_show,
  };
  
  static const struct kernfs_ops sysfs_file_kfops_wo = {
  	.write		= sysfs_kf_write,
  };
  
  static const struct kernfs_ops sysfs_file_kfops_rw = {
  	.seq_show	= sysfs_kf_seq_show,
  	.write		= sysfs_kf_write,
  };

  static const struct kernfs_ops sysfs_prealloc_kfops_ro = {
  	.read		= sysfs_kf_read,
  	.prealloc	= true,
  };

  static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
  	.write		= sysfs_kf_write,
  	.prealloc	= true,
  };
  
  static const struct kernfs_ops sysfs_prealloc_kfops_rw = {

  	.read		= sysfs_kf_read,

  	.write		= sysfs_kf_write,
  	.prealloc	= true,
  };

  static const struct kernfs_ops sysfs_bin_kfops_ro = {
  	.read		= sysfs_kf_bin_read,
  };
  
  static const struct kernfs_ops sysfs_bin_kfops_wo = {
  	.write		= sysfs_kf_bin_write,
  };
  
  static const struct kernfs_ops sysfs_bin_kfops_rw = {
  	.read		= sysfs_kf_bin_read,
  	.write		= sysfs_kf_bin_write,

  };
  
  static const struct kernfs_ops sysfs_bin_kfops_mmap = {
  	.read		= sysfs_kf_bin_read,
  	.write		= sysfs_kf_bin_write,

  	.mmap		= sysfs_kf_bin_mmap,
  };

  int sysfs_add_file_mode_ns(struct kernfs_node *parent,

  			   const struct attribute *attr, bool is_bin,

  			   umode_t mode, const void *ns)

  {

  	struct lock_class_key *key = NULL;

  	const struct kernfs_ops *ops;

  	struct kernfs_node *kn;

  	loff_t size;

  	if (!is_bin) {

  		struct kobject *kobj = parent->priv;

  		const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;
  
  		/* every kobject with an attribute needs a ktype assigned */
  		if (WARN(!sysfs_ops, KERN_ERR
  			 "missing sysfs attribute operations for kobject: %s
  ",
  			 kobject_name(kobj)))
  			return -EINVAL;

  		if (sysfs_ops->show && sysfs_ops->store) {
  			if (mode & SYSFS_PREALLOC)
  				ops = &sysfs_prealloc_kfops_rw;
  			else
  				ops = &sysfs_file_kfops_rw;

  		} else if (sysfs_ops->show) {
  			if (mode & SYSFS_PREALLOC)
  				ops = &sysfs_prealloc_kfops_ro;
  			else
  				ops = &sysfs_file_kfops_ro;
  		} else if (sysfs_ops->store) {

  			if (mode & SYSFS_PREALLOC)
  				ops = &sysfs_prealloc_kfops_wo;
  			else
  				ops = &sysfs_file_kfops_wo;
  		} else

  			ops = &sysfs_file_kfops_empty;

  
  		size = PAGE_SIZE;

  	} else {
  		struct bin_attribute *battr = (void *)attr;

  		if (battr->mmap)
  			ops = &sysfs_bin_kfops_mmap;
  		else if (battr->read && battr->write)

  			ops = &sysfs_bin_kfops_rw;
  		else if (battr->read)
  			ops = &sysfs_bin_kfops_ro;
  		else if (battr->write)
  			ops = &sysfs_bin_kfops_wo;
  		else
  			ops = &sysfs_file_kfops_empty;

  
  		size = battr->size;

  	}

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  	if (!attr->ignore_lockdep)
  		key = attr->key ?: (struct lock_class_key *)&attr->skey;
  #endif

  	kn = __kernfs_create_file(parent, attr->name, mode & 0777, size, ops,

  				  (void *)attr, ns, key);

  	if (IS_ERR(kn)) {
  		if (PTR_ERR(kn) == -EEXIST)
  			sysfs_warn_dup(parent, attr->name);
  		return PTR_ERR(kn);

  	}
  	return 0;
  }

  int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr,

  		   bool is_bin)

  {

  	return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL);

  }

  /**

   * sysfs_create_file_ns - create an attribute file for an object with custom ns
   * @kobj: object we're creating for
   * @attr: attribute descriptor
   * @ns: namespace the new file should belong to

   */

  int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
  			 const void *ns)

  {

  	BUG_ON(!kobj || !kobj->sd || !attr);

  	return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);

  
  }

  EXPORT_SYMBOL_GPL(sysfs_create_file_ns);

  int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
  {
  	int err = 0;
  	int i;
  
  	for (i = 0; ptr[i] && !err; i++)
  		err = sysfs_create_file(kobj, ptr[i]);
  	if (err)
  		while (--i >= 0)
  			sysfs_remove_file(kobj, ptr[i]);
  	return err;
  }

  EXPORT_SYMBOL_GPL(sysfs_create_files);

  
  /**

   * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
   * @kobj: object we're acting for.
   * @attr: attribute descriptor.
   * @group: group name.
   */
  int sysfs_add_file_to_group(struct kobject *kobj,
  		const struct attribute *attr, const char *group)
  {

  	struct kernfs_node *parent;

  	int error;

  	if (group) {

  		parent = kernfs_find_and_get(kobj->sd, group);

  	} else {

  		parent = kobj->sd;
  		kernfs_get(parent);

  	}

  	if (!parent)

  		return -ENOENT;

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

  	return error;
  }
  EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);

  /**

   * sysfs_chmod_file - update the modified mode value on an object attribute.
   * @kobj: object we're acting for.
   * @attr: attribute descriptor.
   * @mode: file permissions.
   *
   */

  int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,

  		     umode_t mode)

  {

  	struct kernfs_node *kn;

  	struct iattr newattrs;

  	int rc;

  	kn = kernfs_find_and_get(kobj->sd, attr->name);
  	if (!kn)

  		return -ENOENT;

  	newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);

  	newattrs.ia_valid = ATTR_MODE;

  	rc = kernfs_setattr(kn, &newattrs);

  	kernfs_put(kn);

  	return rc;

  }
  EXPORT_SYMBOL_GPL(sysfs_chmod_file);

  /**

   * sysfs_break_active_protection - break "active" protection
   * @kobj: The kernel object @attr is associated with.
   * @attr: The attribute to break the "active" protection for.
   *
   * With sysfs, just like kernfs, deletion of an attribute is postponed until
   * all active .show() and .store() callbacks have finished unless this function
   * is called. Hence this function is useful in methods that implement self
   * deletion.
   */
  struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
  						  const struct attribute *attr)
  {
  	struct kernfs_node *kn;
  
  	kobject_get(kobj);
  	kn = kernfs_find_and_get(kobj->sd, attr->name);
  	if (kn)
  		kernfs_break_active_protection(kn);
  	return kn;
  }
  EXPORT_SYMBOL_GPL(sysfs_break_active_protection);
  
  /**
   * sysfs_unbreak_active_protection - restore "active" protection
   * @kn: Pointer returned by sysfs_break_active_protection().
   *
   * Undo the effects of sysfs_break_active_protection(). Since this function
   * calls kernfs_put() on the kernfs node that corresponds to the 'attr'
   * argument passed to sysfs_break_active_protection() that attribute may have
   * been removed between the sysfs_break_active_protection() and
   * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after
   * this function has returned.
   */
  void sysfs_unbreak_active_protection(struct kernfs_node *kn)
  {
  	struct kobject *kobj = kn->parent->priv;
  
  	kernfs_unbreak_active_protection(kn);
  	kernfs_put(kn);
  	kobject_put(kobj);
  }
  EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection);
  
  /**

   * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
   * @kobj: object we're acting for
   * @attr: attribute descriptor
   * @ns: namespace tag of the file to remove

   *

   * Hash the attribute name and namespace tag and kill the victim.

   */

  void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
  			  const void *ns)

  {

  	struct kernfs_node *parent = kobj->sd;

  	kernfs_remove_by_name_ns(parent, attr->name, ns);

  }

  EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);

  /**
   * sysfs_remove_file_self - remove an object attribute from its own method
   * @kobj: object we're acting for
   * @attr: attribute descriptor
   *
   * See kernfs_remove_self() for details.
   */
  bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
  {
  	struct kernfs_node *parent = kobj->sd;
  	struct kernfs_node *kn;
  	bool ret;
  
  	kn = kernfs_find_and_get(parent, attr->name);
  	if (WARN_ON_ONCE(!kn))
  		return false;
  
  	ret = kernfs_remove_self(kn);
  
  	kernfs_put(kn);
  	return ret;
  }

  void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)

  {
  	int i;
  	for (i = 0; ptr[i]; i++)
  		sysfs_remove_file(kobj, ptr[i]);
  }

  EXPORT_SYMBOL_GPL(sysfs_remove_files);

  /**
   * sysfs_remove_file_from_group - remove an attribute file from a group.
   * @kobj: object we're acting for.
   * @attr: attribute descriptor.
   * @group: group name.
   */
  void sysfs_remove_file_from_group(struct kobject *kobj,
  		const struct attribute *attr, const char *group)
  {

  	struct kernfs_node *parent;

  	if (group) {

  		parent = kernfs_find_and_get(kobj->sd, group);

  	} else {

  		parent = kobj->sd;
  		kernfs_get(parent);

  	}

  	if (parent) {
  		kernfs_remove_by_name(parent, attr->name);
  		kernfs_put(parent);

  	}
  }
  EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);

  /**
   *	sysfs_create_bin_file - create binary file for object.
   *	@kobj:	object.
   *	@attr:	attribute descriptor.
   */
  int sysfs_create_bin_file(struct kobject *kobj,
  			  const struct bin_attribute *attr)
  {
  	BUG_ON(!kobj || !kobj->sd || !attr);

  	return sysfs_add_file(kobj->sd, &attr->attr, true);

  }
  EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
  
  /**
   *	sysfs_remove_bin_file - remove binary file for object.
   *	@kobj:	object.
   *	@attr:	attribute descriptor.
   */
  void sysfs_remove_bin_file(struct kobject *kobj,
  			   const struct bin_attribute *attr)
  {

  	kernfs_remove_by_name(kobj->sd, attr->attr.name);

  }
  EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);