func: static void qemu_fill_buffer(QEMUFile *f)
  
  {
  
      int len;
  
  
  
      if (f->is_writable)
  
          return;
  
      if (f->is_file) {
  
          fseek(f->outfile, f->buf_offset, SEEK_SET);
  
          len = fread(f->buf, 1, IO_BUF_SIZE, f->outfile);
  
          if (len < 0)
  
              len = 0;
  
      } else {
  
          len = bdrv_pread(f->bs, f->base_offset + f->buf_offset,
  
                           f->buf, IO_BUF_SIZE);
  
          if (len < 0)
  
              len = 0;
  
      }
  
      f->buf_index = 0;
  
      f->buf_size = len;
  
      f->buf_offset += len;
  
  }
  