CURLOPT_CLOSESOCKETDATA(3) - Man pages

CURLOPT_CLOSESOCKETDATA(3)  Library Functions Manual CURLOPT_CLOSESOCKETDATA(3)

NAME
       CURLOPT_CLOSESOCKETDATA - pointer passed to the socket close callback

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CLOSESOCKETDATA,
                                 void *pointer);

DESCRIPTION
       Pass a pointer that remains untouched by libcurl and passed as the first
       argument  in  the closesocket callback set with CURLOPT_CLOSESOCKETFUNC-
       TION(3).

DEFAULT
       NULL

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).

SEE ALSO
       CURLOPT_CLOSESOCKETFUNCTION(3), CURLOPT_OPENSOCKETFUNCTION(3)

libcurl                            2026-07-12        CURLOPT_CLOSESOCKETDATA(3)

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