CURLSHOPT_USERDATA - pointer passed to the lock and unlock mutex callbacks

Added in curl 7.10.3

The clientp parameter is held verbatim by libcurl and is passed on as the clientp argument to the callbacks set with CURLSHOPT_LOCKFUNC(3) and CURLSHOPT_UNLOCKFUNC(3).

struct secrets { void *custom; }; int main(void) { CURLSHcode sh; struct secrets private_stuff; CURLSH *share = curl_share_init(); sh = curl_share_setopt(share, CURLSHOPT_USERDATA, &private_stuff); if(sh) printf("Error: %s\n", curl_share_strerror(sh)); }

CURLSHOPT_USERDATA - pointer passed to the lock and unlock mutex callbacks

This functionality affects all supported protocols

CURLSHE_OK (zero) means that the option was set properly, non-zero means an error occurred. See libcurl-errors(3) for the full list with descriptions.

CURLSHOPT_LOCKFUNC(3), curl_share_cleanup(3), curl_share_init(3), curl_share_setopt(3) libcurl 2025-06-16 CURLSHOPT_USERDATA(3)

#include <curl/curl.h> CURLSHcode curl_share_setopt(CURLSH *share, CURLSHOPT_USERDATA, void *clientp);