curl-w32/docs/libcurl/opts/CURLOPT_SOCKOPTDATA.md

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---
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_SOCKOPTDATA
Section: 3
Source: libcurl
See-also:
- CURLOPT_OPENSOCKETFUNCTION (3)
- CURLOPT_SOCKOPTFUNCTION (3)
---
# NAME
CURLOPT_SOCKOPTDATA - pointer to pass to sockopt callback
# SYNOPSIS
~~~c
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKOPTDATA, void *pointer);
~~~
# DESCRIPTION
Pass a *pointer* that is untouched by libcurl and passed as the first
argument in the sockopt callback set with CURLOPT_SOCKOPTFUNCTION(3).
# DEFAULT
The default value of this parameter is NULL.
# PROTOCOLS
All
# EXAMPLE
~~~c
static int sockopt_callback(void *clientp, curl_socket_t curlfd,
curlsocktype purpose)
{
int val = *(int *)clientp;
setsockopt((int)curlfd, SOL_SOCKET, SO_RCVBUF,
(const char *)&val, sizeof(val));
return CURL_SOCKOPT_OK;
}
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
int recvbuffersize = 256 * 1024;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
/* call this function to set options for the socket */
curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
curl_easy_setopt(curl, CURLOPT_SOCKOPTDATA, &recvbuffersize);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}
~~~
# AVAILABILITY
Added in 7.16.0
# RETURN VALUE
Returns *CURLE_OK* if the option is supported, and *CURLE_UNKNOWN_OPTION* if not.