/*
   * Copyright (C) 2007 Oracle.  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 "ctree.h"
  #include "disk-io.h"
  #include "hash.h"

  #include "transaction.h"

  /*
   * insert a name into a directory, doing overflow properly if there is a hash
   * collision.  data_size indicates how big the item inserted should be.  On
   * success a struct btrfs_dir_item pointer is returned, otherwise it is
   * an ERR_PTR.
   *
   * The name is not copied into the dir item, you have to do that yourself.
   */

  static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
  						   *trans,
  						   struct btrfs_root *root,
  						   struct btrfs_path *path,
  						   struct btrfs_key *cpu_key,

  						   u32 data_size,
  						   const char *name,
  						   int name_len)

  {

  	struct btrfs_fs_info *fs_info = root->fs_info;

  	int ret;

  	char *ptr;
  	struct btrfs_item *item;

  	struct extent_buffer *leaf;

  
  	ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);

  	if (ret == -EEXIST) {

  		struct btrfs_dir_item *di;

  		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);

  		if (di)
  			return ERR_PTR(-EEXIST);

  		btrfs_extend_item(fs_info, path, data_size);

  	} else if (ret < 0)

  		return ERR_PTR(ret);

  	WARN_ON(ret > 0);

  	leaf = path->nodes[0];

  	item = btrfs_item_nr(path->slots[0]);

  	ptr = btrfs_item_ptr(leaf, path->slots[0], char);

  	BUG_ON(data_size > btrfs_item_size(leaf, item));
  	ptr += btrfs_item_size(leaf, item) - data_size;

  	return (struct btrfs_dir_item *)ptr;

  }

  /*
   * xattrs work a lot like directories, this inserts an xattr item
   * into the tree
   */

  int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,

  			    struct btrfs_root *root,
  			    struct btrfs_path *path, u64 objectid,
  			    const char *name, u16 name_len,
  			    const void *data, u16 data_len)

  {
  	int ret = 0;

  	struct btrfs_dir_item *dir_item;
  	unsigned long name_ptr, data_ptr;
  	struct btrfs_key key, location;
  	struct btrfs_disk_key disk_key;
  	struct extent_buffer *leaf;
  	u32 data_size;

  	if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info))
  		return -ENOSPC;

  
  	key.objectid = objectid;

  	key.type = BTRFS_XATTR_ITEM_KEY;

  	key.offset = btrfs_name_hash(name, name_len);

  
  	data_size = sizeof(*dir_item) + name_len + data_len;
  	dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  					name, name_len);

  	if (IS_ERR(dir_item))
  		return PTR_ERR(dir_item);

  	memset(&location, 0, sizeof(location));
  
  	leaf = path->nodes[0];
  	btrfs_cpu_key_to_disk(&disk_key, &location);
  	btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
  	btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
  	btrfs_set_dir_name_len(leaf, dir_item, name_len);

  	btrfs_set_dir_transid(leaf, dir_item, trans->transid);

  	btrfs_set_dir_data_len(leaf, dir_item, data_len);
  	name_ptr = (unsigned long)(dir_item + 1);
  	data_ptr = (unsigned long)((char *)name_ptr + name_len);
  
  	write_extent_buffer(leaf, name, name_ptr, name_len);
  	write_extent_buffer(leaf, data, data_ptr, data_len);
  	btrfs_mark_buffer_dirty(path->nodes[0]);

  	return ret;
  }

  /*
   * insert a directory item in the tree, doing all the magic for
   * both indexes. 'dir' indicates which objectid to insert it into,
   * 'location' is the key to stuff into the directory item, 'type' is the
   * type of the inode we're pointing to, and 'index' is the sequence number
   * to use for the second index (if one is created).

   * Will return 0 or -ENOMEM

   */

  int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root

  			  *root, const char *name, int name_len,

  			  struct btrfs_inode *dir, struct btrfs_key *location,

  			  u8 type, u64 index)

  {
  	int ret = 0;

  	int ret2 = 0;

  	struct btrfs_path *path;

  	struct btrfs_dir_item *dir_item;

  	struct extent_buffer *leaf;
  	unsigned long name_ptr;

  	struct btrfs_key key;

  	struct btrfs_disk_key disk_key;

  	u32 data_size;

  	key.objectid = btrfs_ino(dir);

  	key.type = BTRFS_DIR_ITEM_KEY;

  	key.offset = btrfs_name_hash(name, name_len);

  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  	path->leave_spinning = 1;

  	btrfs_cpu_key_to_disk(&disk_key, location);

  	data_size = sizeof(*dir_item) + name_len;

  	dir_item = insert_with_overflow(trans, root, path, &key, data_size,
  					name, name_len);

  	if (IS_ERR(dir_item)) {
  		ret = PTR_ERR(dir_item);

  		if (ret == -EEXIST)
  			goto second_insert;

  		goto out_free;

  	}

  	leaf = path->nodes[0];

  	btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
  	btrfs_set_dir_type(leaf, dir_item, type);

  	btrfs_set_dir_data_len(leaf, dir_item, 0);

  	btrfs_set_dir_name_len(leaf, dir_item, name_len);

  	btrfs_set_dir_transid(leaf, dir_item, trans->transid);

  	name_ptr = (unsigned long)(dir_item + 1);

  	write_extent_buffer(leaf, name, name_ptr, name_len);
  	btrfs_mark_buffer_dirty(leaf);

  second_insert:

  	/* FIXME, use some real flag for selecting the extra index */
  	if (root == root->fs_info->tree_root) {
  		ret = 0;

  		goto out_free;

  	}

  	btrfs_release_path(path);

  	ret2 = btrfs_insert_delayed_dir_index(trans, root->fs_info, name,

  			name_len, dir, &disk_key, type, index);

  out_free:

  	btrfs_free_path(path);

  	if (ret)
  		return ret;
  	if (ret2)
  		return ret2;
  	return 0;

  }

  /*
   * lookup a directory item based on name.  'dir' is the objectid
   * we're searching in, and 'mod' tells us if you plan on deleting the
   * item (use mod < 0) or changing the options (use mod > 0)
   */

  struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
  					     struct btrfs_root *root,
  					     struct btrfs_path *path, u64 dir,
  					     const char *name, int name_len,
  					     int mod)

  {

  	int ret;

  	struct btrfs_key key;

  	int ins_len = mod < 0 ? -1 : 0;
  	int cow = mod != 0;

  
  	key.objectid = dir;

  	key.type = BTRFS_DIR_ITEM_KEY;

  	key.offset = btrfs_name_hash(name, name_len);

  	ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
  	if (ret < 0)
  		return ERR_PTR(ret);

  	if (ret > 0)

  		return NULL;

  	return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);

  }

  int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
  				   const char *name, int name_len)
  {
  	int ret;
  	struct btrfs_key key;
  	struct btrfs_dir_item *di;
  	int data_size;
  	struct extent_buffer *leaf;
  	int slot;
  	struct btrfs_path *path;
  
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = dir;

  	key.type = BTRFS_DIR_ITEM_KEY;

  	key.offset = btrfs_name_hash(name, name_len);
  
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  
  	/* return back any errors */
  	if (ret < 0)
  		goto out;
  
  	/* nothing found, we're safe */
  	if (ret > 0) {
  		ret = 0;
  		goto out;
  	}
  
  	/* we found an item, look for our name in the item */

  	di = btrfs_match_dir_item_name(root->fs_info, path, name, name_len);

  	if (di) {
  		/* our exact name was found */
  		ret = -EEXIST;
  		goto out;
  	}
  
  	/*
  	 * see if there is room in the item to insert this
  	 * name
  	 */

  	data_size = sizeof(*di) + name_len;

  	leaf = path->nodes[0];
  	slot = path->slots[0];
  	if (data_size + btrfs_item_size_nr(leaf, slot) +

  	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {

  		ret = -EOVERFLOW;
  	} else {
  		/* plenty of insertion room */
  		ret = 0;
  	}
  out:
  	btrfs_free_path(path);
  	return ret;
  }

  /*
   * lookup a directory item based on index.  'dir' is the objectid
   * we're searching in, and 'mod' tells us if you plan on deleting the
   * item (use mod < 0) or changing the options (use mod > 0)
   *
   * The name is used to make sure the index really points to the name you were
   * looking for.
   */

  struct btrfs_dir_item *
  btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
  			    struct btrfs_root *root,
  			    struct btrfs_path *path, u64 dir,
  			    u64 objectid, const char *name, int name_len,
  			    int mod)
  {
  	int ret;
  	struct btrfs_key key;
  	int ins_len = mod < 0 ? -1 : 0;
  	int cow = mod != 0;
  
  	key.objectid = dir;

  	key.type = BTRFS_DIR_INDEX_KEY;

  	key.offset = objectid;
  
  	ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
  	if (ret < 0)
  		return ERR_PTR(ret);
  	if (ret > 0)
  		return ERR_PTR(-ENOENT);

  	return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);

  }

  struct btrfs_dir_item *
  btrfs_search_dir_index_item(struct btrfs_root *root,
  			    struct btrfs_path *path, u64 dirid,
  			    const char *name, int name_len)
  {
  	struct extent_buffer *leaf;
  	struct btrfs_dir_item *di;
  	struct btrfs_key key;
  	u32 nritems;
  	int ret;
  
  	key.objectid = dirid;
  	key.type = BTRFS_DIR_INDEX_KEY;
  	key.offset = 0;
  
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		return ERR_PTR(ret);
  
  	leaf = path->nodes[0];
  	nritems = btrfs_header_nritems(leaf);
  
  	while (1) {
  		if (path->slots[0] >= nritems) {
  			ret = btrfs_next_leaf(root, path);
  			if (ret < 0)
  				return ERR_PTR(ret);
  			if (ret > 0)
  				break;
  			leaf = path->nodes[0];
  			nritems = btrfs_header_nritems(leaf);
  			continue;
  		}
  
  		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
  		if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
  			break;

  		di = btrfs_match_dir_item_name(root->fs_info, path,
  					       name, name_len);

  		if (di)
  			return di;
  
  		path->slots[0]++;
  	}
  	return NULL;
  }

  struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
  					  struct btrfs_root *root,
  					  struct btrfs_path *path, u64 dir,
  					  const char *name, u16 name_len,
  					  int mod)
  {
  	int ret;
  	struct btrfs_key key;
  	int ins_len = mod < 0 ? -1 : 0;
  	int cow = mod != 0;

  
  	key.objectid = dir;

  	key.type = BTRFS_XATTR_ITEM_KEY;

  	key.offset = btrfs_name_hash(name, name_len);

  	ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
  	if (ret < 0)
  		return ERR_PTR(ret);

  	if (ret > 0)

  		return NULL;

  	return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);

  }

  /*
   * helper function to look at the directory item pointed to by 'path'
   * this walks through all the entries in a dir item and finds one
   * for a specific name.
   */

  struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,

  						 struct btrfs_path *path,
  						 const char *name, int name_len)

  {

  	struct btrfs_dir_item *dir_item;

  	unsigned long name_ptr;

  	u32 total_len;
  	u32 cur = 0;
  	u32 this_len;

  	struct extent_buffer *leaf;

  	leaf = path->nodes[0];

  	dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);

  	total_len = btrfs_item_size_nr(leaf, path->slots[0]);

  	while (cur < total_len) {

  		this_len = sizeof(*dir_item) +

  			btrfs_dir_name_len(leaf, dir_item) +
  			btrfs_dir_data_len(leaf, dir_item);

  		name_ptr = (unsigned long)(dir_item + 1);

  		if (verify_dir_item(fs_info, leaf, path->slots[0], dir_item))
  			return NULL;

  		if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
  		    memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)

  			return dir_item;
  
  		cur += this_len;
  		dir_item = (struct btrfs_dir_item *)((char *)dir_item +
  						     this_len);
  	}
  	return NULL;

  }

  /*
   * given a pointer into a directory item, delete it.  This
   * handles items that have more than one entry in them.
   */

  int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
  			      struct btrfs_root *root,
  			      struct btrfs_path *path,
  			      struct btrfs_dir_item *di)
  {

  	struct extent_buffer *leaf;

  	u32 sub_item_len;
  	u32 item_len;

  	int ret = 0;

  	leaf = path->nodes[0];

  	sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
  		btrfs_dir_data_len(leaf, di);

  	item_len = btrfs_item_size_nr(leaf, path->slots[0]);
  	if (sub_item_len == item_len) {

  		ret = btrfs_del_item(trans, root, path);

  	} else {

  		/* MARKER */
  		unsigned long ptr = (unsigned long)di;
  		unsigned long start;
  
  		start = btrfs_item_ptr_offset(leaf, path->slots[0]);
  		memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,

  			item_len - (ptr + sub_item_len - start));

  		btrfs_truncate_item(root->fs_info, path,
  				    item_len - sub_item_len, 1);

  	}

  	return ret;

  }

  int verify_dir_item(struct btrfs_fs_info *fs_info,

  		    struct extent_buffer *leaf,

  		    int slot,

  		    struct btrfs_dir_item *dir_item)
  {
  	u16 namelen = BTRFS_NAME_LEN;

  	int ret;

  	u8 type = btrfs_dir_type(leaf, dir_item);
  
  	if (type >= BTRFS_FT_MAX) {

  		btrfs_crit(fs_info, "invalid dir item type: %d", (int)type);

  		return 1;
  	}
  
  	if (type == BTRFS_FT_XATTR)
  		namelen = XATTR_NAME_MAX;
  
  	if (btrfs_dir_name_len(leaf, dir_item) > namelen) {

  		btrfs_crit(fs_info, "invalid dir item name len: %u",

  		       (unsigned)btrfs_dir_name_len(leaf, dir_item));

  		return 1;
  	}

  	namelen = btrfs_dir_name_len(leaf, dir_item);
  	ret = btrfs_is_name_len_valid(leaf, slot,
  				      (unsigned long)(dir_item + 1), namelen);
  	if (!ret)
  		return 1;

  	/* BTRFS_MAX_XATTR_SIZE is the same for all dir items */

  	if ((btrfs_dir_data_len(leaf, dir_item) +

  	     btrfs_dir_name_len(leaf, dir_item)) >
  					BTRFS_MAX_XATTR_SIZE(fs_info)) {
  		btrfs_crit(fs_info, "invalid dir item name + data len: %u + %u",

  			   (unsigned)btrfs_dir_name_len(leaf, dir_item),
  			   (unsigned)btrfs_dir_data_len(leaf, dir_item));

  		return 1;
  	}
  
  	return 0;
  }

  
  bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
  			     unsigned long start, u16 name_len)
  {
  	struct btrfs_fs_info *fs_info = leaf->fs_info;
  	struct btrfs_key key;
  	u32 read_start;
  	u32 read_end;
  	u32 item_start;
  	u32 item_end;
  	u32 size;
  	bool ret = true;
  
  	ASSERT(start > BTRFS_LEAF_DATA_OFFSET);
  
  	read_start = start - BTRFS_LEAF_DATA_OFFSET;
  	read_end = read_start + name_len;
  	item_start = btrfs_item_offset_nr(leaf, slot);
  	item_end = btrfs_item_end_nr(leaf, slot);
  
  	btrfs_item_key_to_cpu(leaf, &key, slot);
  
  	switch (key.type) {
  	case BTRFS_DIR_ITEM_KEY:
  	case BTRFS_XATTR_ITEM_KEY:
  	case BTRFS_DIR_INDEX_KEY:
  		size = sizeof(struct btrfs_dir_item);
  		break;
  	case BTRFS_INODE_REF_KEY:
  		size = sizeof(struct btrfs_inode_ref);
  		break;
  	case BTRFS_INODE_EXTREF_KEY:
  		size = sizeof(struct btrfs_inode_extref);
  		break;
  	case BTRFS_ROOT_REF_KEY:
  	case BTRFS_ROOT_BACKREF_KEY:
  		size = sizeof(struct btrfs_root_ref);
  		break;
  	default:
  		ret = false;
  		goto out;
  	}
  
  	if (read_start < item_start) {
  		ret = false;
  		goto out;
  	}
  	if (read_end > item_end) {
  		ret = false;
  		goto out;
  	}
  
  	/* there shall be item(s) before name */
  	if (read_start - item_start < size) {
  		ret = false;
  		goto out;
  	}

  out:
  	if (!ret)
  		btrfs_crit(fs_info, "invalid dir item name len: %u",
  			   (unsigned int)name_len);
  	return ret;
  }