1--- 2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3SPDX-License-Identifier: curl 4Title: CURLSHOPT_LOCKFUNC 5Section: 3 6Source: libcurl 7See-also: 8 - CURLSHOPT_UNLOCKFUNC (3) 9 - curl_share_cleanup (3) 10 - curl_share_init (3) 11 - curl_share_setopt (3) 12Protocol: 13 - All 14--- 15 16# NAME 17 18CURLSHOPT_LOCKFUNC - mutex lock callback 19 20# SYNOPSIS 21 22~~~c 23#include <curl/curl.h> 24 25void lockcb(CURL *handle, curl_lock_data data, curl_lock_access access, 26 void *clientp); 27 28CURLSHcode curl_share_setopt(CURLSH *share, CURLSHOPT_LOCKFUNC, lockcb); 29~~~ 30 31# DESCRIPTION 32 33Set a mutex lock callback for the share object, to allow it to get used by 34multiple threads concurrently. There is a corresponding 35CURLSHOPT_UNLOCKFUNC(3) callback called when the mutex is again released. 36 37The *lockcb* argument must be a pointer to a function matching the 38prototype shown above. The arguments to the callback are: 39 40*handle* is the currently active easy handle in use when the share object 41is intended to get used. 42 43The *data* argument tells what kind of data libcurl wants to lock. Make 44sure that the callback uses a different lock for each kind of data. 45 46*access* defines what access type libcurl wants, shared or single. 47 48*clientp* is the private pointer you set with CURLSHOPT_USERDATA(3). 49This pointer is not used by libcurl itself. 50 51# EXAMPLE 52 53~~~c 54extern void mutex_lock(CURL *handle, curl_lock_data data, 55 curl_lock_access access, void *clientp); 56 57int main(void) 58{ 59 CURLSHcode sh; 60 CURLSH *share = curl_share_init(); 61 sh = curl_share_setopt(share, CURLSHOPT_LOCKFUNC, mutex_lock); 62 if(sh) 63 printf("Error: %s\n", curl_share_strerror(sh)); 64} 65~~~ 66 67# AVAILABILITY 68 69Added in 7.10 70 71# RETURN VALUE 72 73CURLSHE_OK (zero) means that the option was set properly, non-zero means an 74error occurred. See libcurl-errors(3) for the full list with 75descriptions. 76