Method write_fd

src/common/buffer.cc:1918–1968

#ifndef _WIN32
int buffer::list::write_fd(int fd) const
{
  // use writev!
  iovec iov[IOV_MAX];
  int iovlen = 0;
  ssize_t bytes = 0;

  auto p = std::cbegin(_buffers);
  while (p != std::cend(_buffers)) {
    if (p->length() > 0) {
      iov[iovlen].iov_base = (void *)p->c_str();
      iov[iovlen].iov_len = p->length();
      bytes += p->length();
      iovlen++;
    }
    ++p;

    if (iovlen == IOV_MAX ||
	p == _buffers.end()) {
      iovec *start = iov;
      int num = iovlen;
      ssize_t wrote;
    retry:
      wrote = ::writev(fd, start, num);
      if (wrote < 0) {
	int err = errno;
	if (err == EINTR)
	  goto retry;
	return -err;
      }
      if (wrote < bytes) {
	// partial write, recover!
	while ((size_t)wrote >= start[0].iov_len) {
	  wrote -= start[0].iov_len;
	  bytes -= start[0].iov_len;
	  start++;
	  num--;
	}
	if (wrote > 0) {
	  start[0].iov_len -= wrote;
	  start[0].iov_base = (char *)start[0].iov_base + wrote;
	  bytes -= wrote;
	}
	goto retry;
      }
      iovlen = 0;
      bytes = 0;
    }
  }
  return 0;
}

int buffer::list::send_fd(int fd) const {
  return buffer::list::write_fd(fd);