Method fill_buffer

evaluation/TMscore.cpp:2086–2136

   */
  template <typename C, typename T>
    bool
    basic_pstreambuf<C,T>::fill_buffer(bool non_blocking)
    {
      const std::streamsize pb1 = this->gptr() - this->eback();
      const std::streamsize pb2 = pbsz;
      const std::streamsize npb = std::min(pb1, pb2);

      char_type* const rbuf = rbuffer();

      if (npb)
        traits_type::move(rbuf + pbsz - npb, this->gptr() - npb, npb);

      std::streamsize rc = -1;

      if (non_blocking)
      {
        const int flags = ::fcntl(rpipe(), F_GETFL);
        if (flags != -1)
        {
          const bool blocking = !(flags & O_NONBLOCK);
          if (blocking)
            ::fcntl(rpipe(), F_SETFL, flags | O_NONBLOCK);  // set non-blocking

          error_ = 0;
          rc = read(rbuf + pbsz, bufsz - pbsz);

          if (rc == -1 && error_ == EAGAIN)  // nothing available
            rc = 0;
          else if (rc == 0)  // EOF
            rc = -1;

          if (blocking)
            ::fcntl(rpipe(), F_SETFL, flags); // restore
        }
      }
      else
        rc = read(rbuf + pbsz, bufsz - pbsz);

      if (rc > 0 || (rc == 0 && non_blocking))
      {
        this->setg( rbuf + pbsz - npb,
                    rbuf + pbsz,
                    rbuf + pbsz + rc );
        return true;
      }
      else
      {
        this->setg(NULL, NULL, NULL);
        return false;
      }
    }

  /**
   * Writes up to @a n characters to the pipe from the buffer @a s.