ASN1_BIT_STRING_get_length
int ASN1_BIT_STRING_get_length(const ASN1_BIT_STRING *, size_t *, int *);
if (!ASN1_BIT_STRING_get_length(abs, &length, &unused)) {
if (!ASN1_BIT_STRING_get_length(fh->hash, &len, &unused_bits)) {