PHP / CURL绑定支持CURLOPT_READFUNCTION选项

The PHP/CURL binding supports the CURLOPT_READFUNCTION option, which allows you to pass data to send chunk-by-chunk using that callback.

几乎完全相同的逻辑，如下面的C示例所示：
http://curl.haxx.se/libcurl/c/post-callback.html

Pretty much exactly the same logic as is shown in this C example: http://curl.haxx.se/libcurl/c/post-callback.html