Function parse_diff_header

src/tools/rbd/action/MergeDiff.cc:30–79

namespace po = boost::program_options;

static int parse_diff_header(int fd, __u8 *tag, string *from, string *to, uint64_t *size)
{
  int r;

  {//header
    char buf[utils::RBD_DIFF_BANNER.size() + 1];
    r = safe_read_exact(fd, buf, utils::RBD_DIFF_BANNER.size());
    if (r < 0)
      return r;

    buf[utils::RBD_DIFF_BANNER.size()] = '\0';
    if (strcmp(buf, utils::RBD_DIFF_BANNER.c_str())) {
      std::cerr << "invalid banner '" << buf << "', expected '"
                << utils::RBD_DIFF_BANNER << "'" << std::endl;
      return -EINVAL;
    }
  }

  while (true) {
    r = safe_read_exact(fd, tag, 1);
    if (r < 0)
      return r;

    if (*tag == RBD_DIFF_FROM_SNAP) {
      r = utils::read_string(fd, 4096, from);   // 4k limit to make sure we don't get a garbage string
      if (r < 0)
        return r;
      dout(2) << " from snap " << *from << dendl;
    } else if (*tag == RBD_DIFF_TO_SNAP) {
      r = utils::read_string(fd, 4096, to);   // 4k limit to make sure we don't get a garbage string
      if (r < 0)
        return r;
      dout(2) << " to snap " << *to << dendl;
    } else if (*tag == RBD_DIFF_IMAGE_SIZE) {
      char buf[8];
      r = safe_read_exact(fd, buf, 8);
      if (r < 0)
        return r;

      bufferlist bl;
      bl.append(buf, 8);
      auto p = bl.cbegin();
      decode(*size, p);
    } else {
      break;
    }
  }

  return 0;
}

static int parse_diff_body(int fd, __u8 *tag, uint64_t *offset, uint64_t *length)
{