.\" generated by cd2nroff 0.1 from CURLSHOPT_LOCKFUNC.md .TH CURLSHOPT_LOCKFUNC 3 "2024-11-07" libcurl .SH NAME CURLSHOPT_LOCKFUNC \- mutex lock callback .SH SYNOPSIS .nf #include void lockcb(CURL *handle, curl_lock_data data, curl_lock_access access, void *clientp); CURLSHcode curl_share_setopt(CURLSH *share, CURLSHOPT_LOCKFUNC, lockcb); .fi .SH DESCRIPTION Set a mutex lock callback for the share object, to allow it to get used by multiple threads concurrently. There is a corresponding \fICURLSHOPT_UNLOCKFUNC(3)\fP callback called when the mutex is again released. The \fIlockcb\fP argument must be a pointer to a function matching the prototype shown above. The arguments to the callback are: \fIhandle\fP is the currently active easy handle in use when the share object is intended to get used. The \fIdata\fP argument tells what kind of data libcurl wants to lock. Make sure that the callback uses a different lock for each kind of data. \fIaccess\fP defines what access type libcurl wants, shared or single. \fIclientp\fP is the private pointer you set with \fICURLSHOPT_USERDATA(3)\fP. This pointer is not used by libcurl itself. .SH PROTOCOLS This functionality affects all supported protocols .SH EXAMPLE .nf extern void mutex_lock(CURL *handle, curl_lock_data data, curl_lock_access access, void *clientp); int main(void) { CURLSHcode sh; CURLSH *share = curl_share_init(); sh = curl_share_setopt(share, CURLSHOPT_LOCKFUNC, mutex_lock); if(sh) printf("Error: %s\\n", curl_share_strerror(sh)); } .fi .SH AVAILABILITY Added in curl 7.10.3 .SH RETURN VALUE CURLSHE_OK (zero) means that the option was set properly, non\-zero means an error occurred. See \fIlibcurl\-errors(3)\fP for the full list with descriptions. .SH SEE ALSO .BR CURLSHOPT_UNLOCKFUNC (3), .BR curl_share_cleanup (3), .BR curl_share_init (3), .BR curl_share_setopt (3)