Method decrypt_bl

src/client/FSCrypt.cc:894–992

}

int FSCryptFDataDenc::decrypt_bl(uint64_t off, uint64_t len, uint64_t pos, const std::vector<Segment>& holes, bufferlist *bl)
{
  auto data_len = bl->length();
  if (data_len == 0)
    return 0;

  auto target_end = off + len;

  bufferlist newbl;

  uint64_t end = off + data_len;
  uint64_t cur_block = fscrypt_block_from_ofs(pos);
  uint64_t block_off = fscrypt_block_start(pos);

  uint64_t start_block_off = block_off;

  auto hiter = holes.begin();

  while (pos < target_end) {
    bool has_hole = false;

    /*
     * Check to see if cur_block is part of a
     * hole. We expect holes to ordered by offset.
     *
     * There is four states it can be in
     * 1. If position is before hole offset, it cannot be part of a hole
     * 2. If hole end is less than position, hole occurs completely before
     * 3. If hole starts after target_end, hole occurs completely after
     * 4. No conditionals are met, is a hole
     */

    while (hiter != holes.end()) {
      uint64_t hofs = hiter->first;
      uint64_t hlen = hiter->second;
      uint64_t hend = hofs + hlen - 1;

      if (pos < hofs)
	break;

      if (hend < pos) {
        ++hiter;
        continue;
      }

      if (hofs >= target_end) {
        hiter = holes.end();
        break;
      }

      has_hole = true;
      break;
    }

    uint64_t needed_pos = (pos > off ? pos : off);
    void *data_pos = bl->c_str() + needed_pos - start_block_off;
    if (!has_hole && *(uint64_t *)data_pos == 0) {
      has_hole = true;