// read/write helpers

static bool write_all(int fd, const void *data, size_t len) {
  debug("sending(%d)\n%.*s\n", fd, (int)len, (char*)data);
  const char *buf = (const char *)data;
  size_t remaining = len;

  while (remaining > 0) {
    ssize_t n = write(fd, buf, remaining);
    if (n < 0) {
      if (errno == EINTR) continue;
      return false;
    }
    if (n == 0) break;
    buf += n;
    remaining -= n;
  }

  return (remaining == 0);
}

static bool write_header_body(int fd, str header, str body){
  unless(quieter_logs) debug("write header (fd:%d) [len:%ld] body [len:%ld]\n", fd, header.len, body.len);
  struct iovec iov[2];
  iov[0].iov_base = header.data;
  iov[0].iov_len = header.len;
  iov[1].iov_base = body.data;
  iov[1].iov_len = body.len;

  // TODO writev() may partially write, we should send remaining partial and rest of buffers (calc by wsz)
  ssize_t const wsz = writev(fd, iov, 2);
  if(wsz < 0){ warnsys("write_header_body"); return false; }
  if(wsz != header.len + body.len) return false;
  return true;
}