static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x)
{
    int i;
    X509 *issuer;
    for (i = 0; i < sk_X509_num(sk); i++) {
        issuer = sk_X509_value(sk, i);
        if (ctx->check_issued(ctx, x, issuer))
            return issuer;
    }
    return NULL;
}

static X509 *find_issuer(X509_STORE_CTX *ctx, STACK_OF(X509) *sk, X509 *x)
{
    int i;
    X509 *issuer;
    for (i = 0; i < sk_X509_num(sk); i++) {
        issuer = sk_X509_value(sk, i);
        if (ctx->check_issued(ctx, x, issuer))
            return issuer;
    }
    return NULL;
}
