int avio_check(const char *url, int flags) { URLContext *h; int ret = ffurl_alloc(&h, url, flags, NULL); if (ret) return ret; if (h->prot->url_check) { ret = h->prot->url_check(h, flags); } else { ret = ffurl_connect(h, NULL); if (ret >= 0) ret = flags; } ffurl_close(h); return ret; }