CURLINFO_PRIVATE - Man Page

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_PRIVATE, char **private);

Pass a pointer to a char pointer to receive the pointer to the private data associated with the curl handle (set with the CURLOPT_PRIVATE(3)). Please note that for internal reasons, the value is returned as a char pointer, although effectively being a 'void *'.

This functionality affects all supported protocols

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    void *pointer = (void *)0x2345454;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");

    /* set the private pointer */
    curl_easy_setopt(curl, CURLOPT_PRIVATE, pointer);
    res = curl_easy_perform(curl);

    /* extract the private pointer again */
    res = curl_easy_getinfo(curl, CURLINFO_PRIVATE, &pointer);

    if(res)
      printf("error: %s\n", curl_easy_strerror(res));

    curl_easy_cleanup(curl);
  }
}

Added in curl 7.10.3

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

CURLOPT_PRIVATE(3), curl_easy_getinfo(3), curl_easy_setopt(3)

curl_easy_getinfo(3), CURLOPT_PRIVATE(3).