/* This function instead of just computing the SHA1 and xoring it
* against digest, also perform the digest of "digest" itself and
* replace the old value with the new one.
*
* So the final digest will be:
*
* digest = SHA1(digest xor SHA1(data))
*
* This function is used every time we want to preserve the order so
* that digest(a,b,c,d) will be different than digest(b,c,d,a)
*
* Also note that mixdigest("foo") followed by mixdigest("bar")
* will lead to a different digest compared to "fo", "obar".
*/
void mixDigest(unsigned char *digest, void *ptr, size_t len) {
SHA1_CTX ctx;
char *s = ptr;
xorDigest(digest,s,len);
SHA1Init(&ctx);
SHA1Update(&ctx,digest,20);
SHA1Final(digest,&ctx);
}
void xorObjectDigest(unsigned char* digest, robj* o)
{
o = getDecodedObject(o);
xorDigest(digest, o->ptr, sdslen(o->ptr));
decrRefCount(o);
}