Pointer passed to the socket close callback
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CLOSESOCKETDATA, void *pointer);
Pass a pointer that will be untouched by libcurl and passed as the first argument in the closesocket callback set with CURLOPT_CLOSESOCKETFUNCTION(3).
The default value of this parameter is NULL.
All except file:
Added in 7.21.7
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.