.\" generated by cd2nroff 0.1 from CURLMOPT_NOTIFYDATA.md
.TH CURLMOPT_NOTIFYDATA 3 "2025-11-13" libcurl
.SH NAME
CURLMOPT_NOTIFYDATA \- custom pointer passed to the notification callback
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_NOTIFYDATA, void *pointer);
.fi
.SH DESCRIPTION
A data \fIpointer\fP to pass to the notification callback set with the
\fICURLMOPT_NOTIFYFUNCTION(3)\fP option.

This pointer is not touched by libcurl but is only passed in as the
notification callback\(aqs \fBclientp\fP argument.
.SH DEFAULT
NULL
.SH PROTOCOLS
This functionality affects all supported protocols
.SH EXAMPLE
.nf
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);
}
.fi
.SH AVAILABILITY
Added in curl 8.17.0
.SH RETURN VALUE
Returns CURLM_OK.
.SH SEE ALSO
.BR CURLMOPT_NOTIFYFUNCTION (3),
.BR curl_multi_notify_disable (3),
.BR curl_multi_notify_enable (3)