fs/btrfs/dir-item.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * BTRFS filesystem implementation for U-Boot
   4  *
   5  * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
   6  */
   7
   8 #include "btrfs.h"
   9
  10 static int verify_dir_item(struct btrfs_dir_item *item, u32 start, u32 total)
  11 {
  12         u16 max_len = BTRFS_NAME_LEN;
  13         u32 end;
  14
  15         if (item->type >= BTRFS_FT_MAX) {
  16                 printf("%s: invalid dir item type: %i\n", __func__, item->type);
  17                 return 1;
  18         }
  19
  20         if (item->type == BTRFS_FT_XATTR)
  21                 max_len = 255; /* XATTR_NAME_MAX */
  22
  23         end = start + sizeof(*item) + item->name_len;
  24         if (item->name_len > max_len || end > total) {
  25                 printf("%s: invalid dir item name len: %u\n", __func__,
  26                        item->name_len);
  27                 return 1;
  28         }
  29
  30         return 0;
  31 }
  32
  33 static struct btrfs_dir_item *
  34 btrfs_match_dir_item_name(struct btrfs_path *path, const char *name,
  35                           int name_len)
  36 {
  37         struct btrfs_dir_item *item;
  38         u32 total_len, cur = 0, this_len;
  39         const char *name_ptr;
  40
  41         item = btrfs_path_item_ptr(path, struct btrfs_dir_item);
  42
  43         total_len = btrfs_path_item_size(path);
  44
  45         while (cur < total_len) {
  46                 btrfs_dir_item_to_cpu(item);
  47                 this_len = sizeof(*item) + item->name_len + item->data_len;
  48                 name_ptr = (const char *) (item + 1);
  49
  50                 if (verify_dir_item(item, cur, total_len))
  51                         return NULL;
  52                 if (item->name_len == name_len && !memcmp(name_ptr, name,
  53                                                           name_len))
  54                         return item;
  55
  56                 cur += this_len;
  57                 item = (struct btrfs_dir_item *) ((u8 *) item + this_len);
  58         }
  59
  60         return NULL;
  61 }
  62
  63 int btrfs_lookup_dir_item(const struct btrfs_root *root, u64 dir,
  64                           const char *name, int name_len,
  65                           struct btrfs_dir_item *item)
  66 {
  67         struct btrfs_path path;
  68         struct btrfs_key key;
  69         struct btrfs_dir_item *res = NULL;
  70
  71         key.objectid = dir;
  72         key.type = BTRFS_DIR_ITEM_KEY;
  73         key.offset = btrfs_name_hash(name, name_len);
  74
  75         if (btrfs_search_tree(root, &key, &path))
  76                 return -1;
  77
  78         if (btrfs_comp_keys_type(&key, btrfs_path_leaf_key(&path)))
  79                 goto out;
  80
  81         res = btrfs_match_dir_item_name(&path, name, name_len);
  82         if (res)
  83                 *item = *res;
  84 out:
  85         btrfs_free_path(&path);
  86         return res ? 0 : -1;
  87 }
  88
  89 int btrfs_readdir(const struct btrfs_root *root, u64 dir,
  90                   btrfs_readdir_callback_t callback)
  91 {
  92         struct btrfs_path path;
  93         struct btrfs_key key, *found_key;
  94         struct btrfs_dir_item *item;
  95         int res = 0;
  96
  97         key.objectid = dir;
  98         key.type = BTRFS_DIR_INDEX_KEY;
  99         key.offset = 0;
 100
 101         if (btrfs_search_tree(root, &key, &path))
 102                 return -1;
 103
 104         do {
 105                 found_key = btrfs_path_leaf_key(&path);
 106                 if (btrfs_comp_keys_type(&key, found_key))
 107                         break;
 108
 109                 item = btrfs_path_item_ptr(&path, struct btrfs_dir_item);
 110                 btrfs_dir_item_to_cpu(item);
 111
 112                 if (verify_dir_item(item, 0, sizeof(*item) + item->name_len))
 113                         continue;
 114                 if (item->type == BTRFS_FT_XATTR)
 115                         continue;
 116
 117                 if (callback(root, item))
 118                         break;
 119         } while (!(res = btrfs_next_slot(&path)));
 120
 121         btrfs_free_path(&path);
 122
 123         return res < 0 ? -1 : 0;
 124 }