/*
   * Copyright (C) 2007 Red Hat.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * 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.
   */
  
  #include <linux/init.h>
  #include <linux/fs.h>
  #include <linux/slab.h>
  #include <linux/rwsem.h>
  #include <linux/xattr.h>

  #include <linux/security.h>

  #include "ctree.h"
  #include "btrfs_inode.h"
  #include "transaction.h"
  #include "xattr.h"
  #include "disk-io.h"

  ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
  				void *buffer, size_t size)

  {
  	struct btrfs_dir_item *di;
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_path *path;
  	struct extent_buffer *leaf;

  	int ret = 0;
  	unsigned long data_ptr;

  
  	path = btrfs_alloc_path();

  	if (!path)

  		return -ENOMEM;

  	/* lookup the xattr by name */
  	di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
  				strlen(name), 0);

  	if (!di) {

  		ret = -ENODATA;
  		goto out;

  	} else if (IS_ERR(di)) {
  		ret = PTR_ERR(di);
  		goto out;

  	}
  
  	leaf = path->nodes[0];
  	/* if size is 0, that means we want the size of the attr */
  	if (!size) {
  		ret = btrfs_dir_data_len(leaf, di);
  		goto out;
  	}
  
  	/* now get the data out of our dir_item */
  	if (btrfs_dir_data_len(leaf, di) > size) {
  		ret = -ERANGE;
  		goto out;
  	}

  
  	/*
  	 * The way things are packed into the leaf is like this
  	 * |struct btrfs_dir_item|name|data|
  	 * where name is the xattr name, so security.foo, and data is the
  	 * content of the xattr.  data_ptr points to the location in memory
  	 * where the data starts in the in memory leaf
  	 */

  	data_ptr = (unsigned long)((char *)(di + 1) +
  				   btrfs_dir_name_len(leaf, di));
  	read_extent_buffer(leaf, buffer, data_ptr,

  			   btrfs_dir_data_len(leaf, di));

  	ret = btrfs_dir_data_len(leaf, di);
  
  out:

  	btrfs_free_path(path);
  	return ret;
  }

  static int do_setxattr(struct btrfs_trans_handle *trans,
  		       struct inode *inode, const char *name,
  		       const void *value, size_t size, int flags)

  {
  	struct btrfs_dir_item *di;
  	struct btrfs_root *root = BTRFS_I(inode)->root;

  	struct btrfs_path *path;

  	size_t name_len = strlen(name);
  	int ret = 0;
  
  	if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
  		return -ENOSPC;

  
  	path = btrfs_alloc_path();

  	if (!path)

  		return -ENOMEM;

  	/* first lets see if we already have this xattr */
  	di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
  				strlen(name), -1);
  	if (IS_ERR(di)) {
  		ret = PTR_ERR(di);
  		goto out;
  	}
  
  	/* ok we already have this xattr, lets remove it */
  	if (di) {
  		/* if we want create only exit */
  		if (flags & XATTR_CREATE) {
  			ret = -EEXIST;
  			goto out;
  		}
  
  		ret = btrfs_delete_one_dir_name(trans, root, path, di);

  		BUG_ON(ret);

  		btrfs_release_path(root, path);
  
  		/* if we don't have a value then we are removing the xattr */

  		if (!value)

  			goto out;

  	} else {
  		btrfs_release_path(root, path);
  
  		if (flags & XATTR_REPLACE) {
  			/* we couldn't find the attr to replace */
  			ret = -ENODATA;
  			goto out;
  		}

  	}
  
  	/* ok we have to create a completely new xattr */

  	ret = btrfs_insert_xattr_item(trans, root, path, inode->i_ino,
  				      name, name_len, value, size);
  	BUG_ON(ret);
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  int __btrfs_setxattr(struct btrfs_trans_handle *trans,
  		     struct inode *inode, const char *name,
  		     const void *value, size_t size, int flags)
  {
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	int ret;
  
  	if (trans)
  		return do_setxattr(trans, inode, name, value, size, flags);

  	trans = btrfs_start_transaction(root, 2);
  	if (IS_ERR(trans))
  		return PTR_ERR(trans);

  	btrfs_set_trans_block_group(trans, inode);

  	ret = do_setxattr(trans, inode, name, value, size, flags);
  	if (ret)
  		goto out;
  
  	inode->i_ctime = CURRENT_TIME;
  	ret = btrfs_update_inode(trans, root, inode);
  	BUG_ON(ret);
  out:
  	btrfs_end_transaction_throttle(trans, root);

  	return ret;
  }
  
  ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
  {
  	struct btrfs_key key, found_key;
  	struct inode *inode = dentry->d_inode;
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	struct btrfs_path *path;

  	struct extent_buffer *leaf;
  	struct btrfs_dir_item *di;

  	int ret = 0, slot, advance;

  	size_t total_size = 0, size_left = size;

  	unsigned long name_ptr;

  	size_t name_len;

  	u32 nritems;
  
  	/*
  	 * ok we want all objects associated with this id.
  	 * NOTE: we set key.offset = 0; because we want to start with the
  	 * first xattr that we find and walk forward
  	 */
  	key.objectid = inode->i_ino;
  	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
  	key.offset = 0;
  
  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  	path->reada = 2;

  	/* search for our xattrs */
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		goto err;

  	advance = 0;
  	while (1) {
  		leaf = path->nodes[0];
  		nritems = btrfs_header_nritems(leaf);
  		slot = path->slots[0];
  
  		/* this is where we start walking through the path */
  		if (advance || slot >= nritems) {
  			/*
  			 * if we've reached the last slot in this leaf we need
  			 * to go to the next leaf and reset everything
  			 */
  			if (slot >= nritems-1) {
  				ret = btrfs_next_leaf(root, path);
  				if (ret)
  					break;
  				leaf = path->nodes[0];
  				nritems = btrfs_header_nritems(leaf);
  				slot = path->slots[0];
  			} else {
  				/*
  				 * just walking through the slots on this leaf
  				 */
  				slot++;
  				path->slots[0]++;
  			}
  		}
  		advance = 1;

  		btrfs_item_key_to_cpu(leaf, &found_key, slot);
  
  		/* check to make sure this item is what we want */
  		if (found_key.objectid != key.objectid)
  			break;
  		if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
  			break;
  
  		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);

  		name_len = btrfs_dir_name_len(leaf, di);
  		total_size += name_len + 1;

  
  		/* we are just looking for how big our buffer needs to be */
  		if (!size)
  			continue;

  		if (!buffer || (name_len + 1) > size_left) {

  			ret = -ERANGE;

  			goto err;

  		}

  		name_ptr = (unsigned long)(di + 1);
  		read_extent_buffer(leaf, buffer, name_ptr, name_len);
  		buffer[name_len] = '\0';
  
  		size_left -= name_len + 1;
  		buffer += name_len + 1;

  	}
  	ret = total_size;
  
  err:

  	btrfs_free_path(path);
  
  	return ret;
  }
  
  /*

   * List of handlers for synthetic system.* attributes.  All real ondisk
   * attributes are handled directly.
   */

  const struct xattr_handler *btrfs_xattr_handlers[] = {

  #ifdef CONFIG_BTRFS_FS_POSIX_ACL

  	&btrfs_xattr_acl_access_handler,
  	&btrfs_xattr_acl_default_handler,
  #endif
  	NULL,
  };
  
  /*
   * Check if the attribute is in a supported namespace.
   *
   * This applied after the check for the synthetic attributes in the system
   * namespace.

   */

  static bool btrfs_is_valid_xattr(const char *name)
  {

  	return !strncmp(name, XATTR_SECURITY_PREFIX,
  			XATTR_SECURITY_PREFIX_LEN) ||

  	       !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
  	       !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
  	       !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);

  }

  ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
  		       void *buffer, size_t size)
  {
  	/*
  	 * If this is a request for a synthetic attribute in the system.*
  	 * namespace use the generic infrastructure to resolve a handler
  	 * for it via sb->s_xattr.
  	 */
  	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
  		return generic_getxattr(dentry, name, buffer, size);

  	if (!btrfs_is_valid_xattr(name))
  		return -EOPNOTSUPP;
  	return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
  }

  int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
  		   size_t size, int flags)
  {

  	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
  
  	/*
  	 * The permission on security.* and system.* is not checked
  	 * in permission().
  	 */
  	if (btrfs_root_readonly(root))
  		return -EROFS;

  	/*
  	 * If this is a request for a synthetic attribute in the system.*
  	 * namespace use the generic infrastructure to resolve a handler
  	 * for it via sb->s_xattr.
  	 */
  	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
  		return generic_setxattr(dentry, name, value, size, flags);

  	if (!btrfs_is_valid_xattr(name))
  		return -EOPNOTSUPP;

  	if (size == 0)
  		value = "";  /* empty EA, do not remove */

  
  	return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
  				flags);

  }
  
  int btrfs_removexattr(struct dentry *dentry, const char *name)
  {

  	struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
  
  	/*
  	 * The permission on security.* and system.* is not checked
  	 * in permission().
  	 */
  	if (btrfs_root_readonly(root))
  		return -EROFS;

  	/*
  	 * If this is a request for a synthetic attribute in the system.*
  	 * namespace use the generic infrastructure to resolve a handler
  	 * for it via sb->s_xattr.
  	 */
  	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
  		return generic_removexattr(dentry, name);
  
  	if (!btrfs_is_valid_xattr(name))
  		return -EOPNOTSUPP;

  
  	return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
  				XATTR_REPLACE);

  }

  int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
  			      struct inode *inode, struct inode *dir)

  {
  	int err;
  	size_t len;
  	void *value;
  	char *suffix;
  	char *name;
  
  	err = security_inode_init_security(inode, dir, &suffix, &value, &len);
  	if (err) {
  		if (err == -EOPNOTSUPP)
  			return 0;
  		return err;
  	}
  
  	name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1,
  		       GFP_NOFS);
  	if (!name) {
  		err = -ENOMEM;
  	} else {
  		strcpy(name, XATTR_SECURITY_PREFIX);
  		strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);

  		err = __btrfs_setxattr(trans, inode, name, value, len, 0);

  		kfree(name);
  	}
  
  	kfree(suffix);
  	kfree(value);
  	return err;
  }