CURLOPT_DEBUGDATA(3) Library Functions Manual CURLOPT_DEBUGDATA(3) NAME CURLOPT_DEBUGDATA - pointer passed to the debug callback SYNOPSIS #include CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DEBUGDATA, void *pointer); DESCRIPTION Pass a pointer to whatever you want passed in to your CURLOPT_DEBUGFUNCTION(3) in the last void * argument. This pointer is not used by libcurl, it is only passed to the callback. DEFAULT NULL PROTOCOLS All EXAMPLE struct data { void *custom; }; static int my_trace(CURL *handle, curl_infotype type, char *data, size_t size, void *clientp) { struct data *mine = clientp; printf("our ptr: %p\n", mine->custom); /* output debug info */ } int main(void) { CURL *curl; CURLcode res; struct data my_tracedata; curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, my_trace); curl_easy_setopt(curl, CURLOPT_DEBUGDATA, &my_tracedata); /* the DEBUGFUNCTION has no effect until we enable VERBOSE */ curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/"); res = curl_easy_perform(curl); /* always cleanup */ curl_easy_cleanup(curl); } return 0; } AVAILABILITY Always RETURN VALUE Returns CURLE_OK SEE ALSO CURLOPT_DEBUGFUNCTION(3), CURLOPT_STDERR(3) libcurl April 26 2024 CURLOPT_DEBUGDATA(3)