// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 */

#include "messages.h"
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "accessors.h"
#include "dir-item.h"
#include "delayed-inode.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,
                                                   const struct btrfs_key *cpu_key,
                                                   u32 data_size,
                                                   const char *name,
                                                   int name_len)
{
        int ret;
        char *ptr;
        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(path, name, name_len);
                if (di)
                        return ERR_PTR(-EEXIST);
                btrfs_extend_item(trans, path, data_size);
        } else if (ret < 0)
                return ERR_PTR(ret);
        WARN_ON(ret > 0);
        leaf = path->nodes[0];
        ptr = btrfs_item_ptr(leaf, path->slots[0], char);
        ASSERT(data_size <= btrfs_item_size(leaf, path->slots[0]));
        ptr += btrfs_item_size(leaf, path->slots[0]) - 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_flags(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);

        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,
                          const struct fscrypt_str *name, struct btrfs_inode *dir,
                          const struct btrfs_key *location, u8 type, u64 index)
{
        int ret = 0;
        int ret2 = 0;
        struct btrfs_root *root = dir->root;
        BTRFS_PATH_AUTO_FREE(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, name->len);

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        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, name->len);
        if (IS_ERR(dir_item)) {
                ret = PTR_ERR(dir_item);
                if (ret == -EEXIST)
                        goto second_insert;
                goto out_free;
        }

        if (IS_ENCRYPTED(&dir->vfs_inode))
                type |= BTRFS_FT_ENCRYPTED;

        leaf = path->nodes[0];
        btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
        btrfs_set_dir_flags(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, name_ptr, name->len);

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, name->name, name->len, dir,
                                              &disk_key, type, index);
out_free:
        if (ret)
                return ret;
        if (ret2)
                return ret2;
        return 0;
}

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

        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(path, name, name_len);
}

/*
 * Lookup for a directory item by name.
 *
 * @trans:      The transaction handle to use. Can be NULL if @mod is 0.
 * @root:       The root of the target tree.
 * @path:       Path to use for the search.
 * @dir:        The inode number (objectid) of the directory.
 * @name:       The name associated to the directory entry we are looking for.
 * @name_len:   The length of the name.
 * @mod:        Used to indicate if the tree search is meant for a read only
 *              lookup, for a modification lookup or for a deletion lookup, so
 *              its value should be 0, 1 or -1, respectively.
 *
 * Returns: NULL if the dir item does not exists, an error pointer if an error
 * happened, or a pointer to a dir item if a dir item exists for the given name.
 */
struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
                                             struct btrfs_root *root,
                                             struct btrfs_path *path, u64 dir,
                                             const struct fscrypt_str *name,
                                             int mod)
{
        struct btrfs_key key;
        struct btrfs_dir_item *di;

        key.objectid = dir;
        key.type = BTRFS_DIR_ITEM_KEY;
        key.offset = btrfs_name_hash(name->name, name->len);

        di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
                                    name->len, mod);
        if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
                return NULL;

        return di;
}

int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir_ino,
                                   const struct fscrypt_str *name)
{
        int ret;
        struct btrfs_key key;
        struct btrfs_dir_item *di;
        int data_size;
        struct extent_buffer *leaf;
        int slot;
        BTRFS_PATH_AUTO_FREE(path);

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        key.objectid = dir_ino;
        key.type = BTRFS_DIR_ITEM_KEY;
        key.offset = btrfs_name_hash(name->name, name->len);

        di = btrfs_lookup_match_dir(NULL, root, path, &key, name->name,
                                    name->len, 0);
        if (IS_ERR(di)) {
                ret = PTR_ERR(di);
                /* Nothing found, we're safe */
                if (ret == -ENOENT)
                        return 0;

                if (ret < 0)
                        return ret;
        }

        /* we found an item, look for our name in the item */
        if (di) {
                /* our exact name was found */
                return -EEXIST;
        }

        /* 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(leaf, slot) +
            sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
                return -EOVERFLOW;
        }

        /* Plenty of insertion room. */
        return 0;
}

/*
 * Lookup for a directory index item by name and index number.
 *
 * @trans:      The transaction handle to use. Can be NULL if @mod is 0.
 * @root:       The root of the target tree.
 * @path:       Path to use for the search.
 * @dir:        The inode number (objectid) of the directory.
 * @index:      The index number.
 * @name:       The name associated to the directory entry we are looking for.
 * @name_len:   The length of the name.
 * @mod:        Used to indicate if the tree search is meant for a read only
 *              lookup, for a modification lookup or for a deletion lookup, so
 *              its value should be 0, 1 or -1, respectively.
 *
 * Returns: NULL if the dir index item does not exists, an error pointer if an
 * error happened, or a pointer to a dir item if the dir index item exists and
 * matches the criteria (name and index number).
 */
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 index, const struct fscrypt_str *name, int mod)
{
        struct btrfs_dir_item *di;
        struct btrfs_key key;

        key.objectid = dir;
        key.type = BTRFS_DIR_INDEX_KEY;
        key.offset = index;

        di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
                                    name->len, mod);
        if (di == ERR_PTR(-ENOENT))
                return NULL;

        return di;
}

struct btrfs_dir_item *
btrfs_search_dir_index_item(struct btrfs_root *root, struct btrfs_path *path,
                            u64 dirid, const struct fscrypt_str *name)
{
        struct btrfs_dir_item *di;
        struct btrfs_key key;
        int ret;

        key.objectid = dirid;
        key.type = BTRFS_DIR_INDEX_KEY;
        key.offset = 0;

        btrfs_for_each_slot(root, &key, &key, path, ret) {
                if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
                        break;

                di = btrfs_match_dir_item_name(path, name->name, name->len);
                if (di)
                        return di;
        }
        /* Adjust return code if the key was not found in the next leaf. */
        if (ret >= 0)
                ret = -ENOENT;

        return ERR_PTR(ret);
}

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)
{
        struct btrfs_key key;
        struct btrfs_dir_item *di;

        key.objectid = dir;
        key.type = BTRFS_XATTR_ITEM_KEY;
        key.offset = btrfs_name_hash(name, name_len);

        di = btrfs_lookup_match_dir(trans, root, path, &key, name, name_len, mod);
        if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
                return NULL;

        return di;
}

/*
 * 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(const 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(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 (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,
                              const 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(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(trans, path, item_len - sub_item_len, 1);
        }
        return ret;
}