md_ctrl
if (md && md->md_ctrl) {
rv = md->md_ctrl(NULL, EVP_MD_CTRL_MICALG, 0, &micstr);
static long md_ctrl(BIO *h, int cmd, long arg1, void *arg2);
.ctrl = md_ctrl,
if (!ctx->digest->md_ctrl) {
ret = ctx->digest->md_ctrl(ctx, type, arg, ptr);
int (*md_ctrl)(EVP_MD_CTX *ctx, int cmd, int p1, void *p2);