CURLMOPT_NOTIFYDATA(3)     Library Functions Manual     CURLMOPT_NOTIFYDATA(3)

NAME
       CURLMOPT_NOTIFYDATA - custom pointer passed to the notification
       callback

SYNOPSIS
       #include <curl/curl.h>

       CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_NOTIFYDATA, void *pointer);

DESCRIPTION
       A data pointer to pass to the notification callback set with the
       CURLMOPT_NOTIFYFUNCTION(3) option.

       This pointer is not touched by libcurl but is only passed in as the
       notification callback's clientp argument.

DEFAULT
       NULL

PROTOCOLS
       This functionality affects all supported protocols

EXAMPLE
       struct priv {
         void *ours;
       };

       static void notify_cb(CURLM *multi, unsigned int notification,
                             CURL *easy, void *notifyp)
       {
         struct priv *p = notifyp;
         printf("my ptr: %p\n", p->ours);
         /* ... */
       }

       int main(void)
       {
         struct priv setup;
         CURLM *multi = curl_multi_init();
         /* ... use socket callback and custom pointer */
         curl_multi_setopt(multi, CURLMOPT_NOTIFYFUNCTION, notify_cb);
         curl_multi_setopt(multi, CURLMOPT_NOTIFYDATA, &setup);
         curl_multi_notify_enable(multi, CURLMNOTIFY_INFO_READ);
       }

AVAILABILITY
       Added in curl 8.17.0

RETURN VALUE
       Returns CURLM_OK.

SEE ALSO
       CURLMOPT_NOTIFYFUNCTION(3), curl_multi_notify_disable(3),
       curl_multi_notify_enable(3)

libcurl                           2025-11-13            CURLMOPT_NOTIFYDATA(3)