curl / libcurl / API / curl_multi_setopt / CURLMOPT_SOCKETDATA

CURLMOPT_SOCKETDATA explained

Name

CURLMOPT_SOCKETDATA - custom pointer passed to the socket callback

Synopsis

#include <curl/curl.h>
 
CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_SOCKETDATA, void *pointer);

Description

A data pointer to pass to the socket callback set with the CURLMOPT_SOCKETFUNCTION option.

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

Default

NULL

Protocols

All

Example

struct priv {
  void *ours;
};
 
static int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp)
{
  struct priv *p = sockp;
  printf("my ptr: %p\n", p->ours);
 
  if(what == CURL_POLL_REMOVE) {
    /* remove the socket from our collection */
  }
  if(what & CURL_POLL_IN) {
    /* wait for read on this socket */
  }
  if(what & CURL_POLL_OUT) {
    /* wait for write on this socket */
  }
 
  return 0;
}
 
int main(void)
{
  struct priv setup;
  CURLM *multi = curl_multi_init();
  /* ... use socket callback and custom pointer */
  curl_multi_setopt(multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
  curl_multi_setopt(multi, CURLMOPT_SOCKETDATA, &setup);
}

Availability

Added in 7.15.4

Return value

Returns CURLM_OK.