Tribblix: manual page: CURLOPT_CLOSESOCKETFUNCTION.3

CURLOPT_CLOSESOCKETFUNCTION(3) Introduction to Library Functions

NAME

CURLOPT_CLOSESOCKETFUNCTION - callback to socket close replacement

SYNOPSIS

#include <curl/curl.h>

int closesocket_callback(void *clientp, curl_socket_t item);

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CLOSESOCKETFUNCTION,
closesocket_callback);

DESCRIPTION

Pass a pointer to your callback function, which should match the
prototype shown above.

This callback function gets called by libcurl instead of the close(3)
or closesocket(3) call when sockets are closed (not for any other
file descriptors). This is pretty much the reverse to the
CURLOPT_OPENSOCKETFUNCTION(3) option. Return 0 to signal success and
1 if there was an error.

The clientp pointer is set with CURLOPT_CLOSESOCKETDATA(3). item is
the socket libcurl wants to be closed.

Note that when using multi/share handles, your callback may get
invoked even after the easy handle has been cleaned up. The callback
and data is inherited by a new connection and that connection may
live longer than the transfer itself in the multi/share handle's
connection cache.

DEFAULT

Use the standard socket close function.

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

struct priv {
void *custom;
};

static int closesocket(void *clientp, curl_socket_t item)
{
struct priv *my = clientp;
printf("our ptr: %p\n", my->custom);

printf("libcurl wants to close %d now\n", (int)item);
return 0;
}

int main(void)
{
struct priv myown;
CURL *curl = curl_easy_init();

/* call this function to close sockets */
curl_easy_setopt(curl, CURLOPT_CLOSESOCKETFUNCTION, closesocket);
curl_easy_setopt(curl, CURLOPT_CLOSESOCKETDATA, &myown);

curl_easy_perform(curl);
curl_easy_cleanup(curl);
}

AVAILABILITY

Added in curl 7.21.7

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).