/* Return the value associated to the key with a name obtained using
* the following rules:
*
* 1) The first occurrence of '*' in 'pattern' is substituted with 'subst'.
*
* 2) If 'pattern' matches the "->" string, everything on the left of
* the arrow is treated as the name of a hash field, and the part on the
* left as the key name containing a hash. The value of the specified
* field is returned.
*
* 3) If 'pattern' equals "#", the function simply returns 'subst' itself so
* that the SORT command can be used like: SORT key GET # to retrieve
* the Set/List elements directly.
*
* The returned object will always have its refcount increased by 1
* when it is non-NULL. */
robj *lookupKeyByPattern(redisDb *db, robj *pattern, robj *subst) {
char *p, *f, *k;
sds spat, ssub;
robj *keyobj, *fieldobj = NULL, *o;
int prefixlen, sublen, postfixlen, fieldlen;
/* If the pattern is "#" return the substitution object itself in order
* to implement the "SORT ... GET #" feature. */
spat = pattern->ptr;
if (spat[0] == '#' && spat[1] == '\0') {
incrRefCount(subst);
return subst;
}
/* The substitution object may be specially encoded. If so we create
* a decoded object on the fly. Otherwise getDecodedObject will just
* increment the ref count, that we'll decrement later. */
subst = getDecodedObject(subst);
ssub = subst->ptr;
/* If we can't find '*' in the pattern we return NULL as to GET a
* fixed key does not make sense. */
p = strchr(spat,'*');
if (!p) {
decrRefCount(subst);
return NULL;
}
/* Find out if we're dealing with a hash dereference. */
if ((f = strstr(p+1, "->")) != NULL && *(f+2) != '\0') {
fieldlen = sdslen(spat)-(f-spat)-2;
fieldobj = createStringObject(f+2,fieldlen);
} else {
fieldlen = 0;
}
/* Perform the '*' substitution. */
prefixlen = p-spat;
sublen = sdslen(ssub);
postfixlen = sdslen(spat)-(prefixlen+1)-(fieldlen ? fieldlen+2 : 0);
keyobj = createStringObject(NULL,prefixlen+sublen+postfixlen);
k = keyobj->ptr;
memcpy(k,spat,prefixlen);
memcpy(k+prefixlen,ssub,sublen);
memcpy(k+prefixlen+sublen,p+1,postfixlen);
decrRefCount(subst); /* Incremented by decodeObject() */
/* Lookup substituted key */
o = lookupKeyRead(db,keyobj);
if (o == NULL) goto noobj;
if (fieldobj) {
if (o->type != REDIS_HASH) goto noobj;
/* Retrieve value from hash by the field name. This operation
* already increases the refcount of the returned object. */
o = hashTypeGetObject(o, fieldobj);
} else {
if (o->type != REDIS_STRING) goto noobj;
/* Every object that this function returns needs to have its refcount
* increased. sortCommand decreases it again. */
incrRefCount(o);
}
decrRefCount(keyobj);
if (fieldobj) decrRefCount(fieldobj);
return o;
noobj:
decrRefCount(keyobj);
if (fieldlen) decrRefCount(fieldobj);
return NULL;
}
/* Return the value associated to the key with a name obtained
* substituting the first occurence of '*' in 'pattern' with 'subst'.
* The returned object will always have its refcount increased by 1
* when it is non-NULL. */
robj *lookupKeyByPattern(redisDb *db, robj *pattern, robj *subst) {
char *p, *f;
sds spat, ssub;
robj keyobj, fieldobj, *o;
int prefixlen, sublen, postfixlen, fieldlen;
/* Expoit the internal sds representation to create a sds string allocated on the stack in order to make this function faster */
struct {
int len;
int free;
char buf[REDIS_SORTKEY_MAX+1];
} keyname, fieldname;
/* If the pattern is "#" return the substitution object itself in order
* to implement the "SORT ... GET #" feature. */
spat = pattern->ptr;
if (spat[0] == '#' && spat[1] == '\0') {
incrRefCount(subst);
return subst;
}
/* The substitution object may be specially encoded. If so we create
* a decoded object on the fly. Otherwise getDecodedObject will just
* increment the ref count, that we'll decrement later. */
subst = getDecodedObject(subst);
ssub = subst->ptr;
if (sdslen(spat)+sdslen(ssub)-1 > REDIS_SORTKEY_MAX) return NULL;
p = strchr(spat,'*');
if (!p) {
decrRefCount(subst);
return NULL;
}
/* Find out if we're dealing with a hash dereference. */
if ((f = strstr(p+1, "->")) != NULL) {
fieldlen = (int)(sdslen(spat)-(f-spat));
/* this also copies \0 character */
memcpy(fieldname.buf,f+2,fieldlen-1);
fieldname.len = fieldlen-2;
} else {
fieldlen = 0;
}
prefixlen = (int)(p-spat);
sublen = (int)sdslen(ssub);
postfixlen = (int)(sdslen(spat)-(prefixlen+1)-fieldlen);
memcpy(keyname.buf,spat,prefixlen);
memcpy(keyname.buf+prefixlen,ssub,sublen);
memcpy(keyname.buf+prefixlen+sublen,p+1,postfixlen);
keyname.buf[prefixlen+sublen+postfixlen] = '\0';
keyname.len = prefixlen+sublen+postfixlen;
decrRefCount(subst);
/* Lookup substituted key */
initStaticStringObject(keyobj,((char*)&keyname)+(sizeof(struct sdshdr)));
o = lookupKeyRead(db,&keyobj);
if (o == NULL) return NULL;
if (fieldlen > 0) {
if (o->type != REDIS_HASH || fieldname.len < 1) return NULL;
/* Retrieve value from hash by the field name. This operation
* already increases the refcount of the returned object. */
initStaticStringObject(fieldobj,((char*)&fieldname)+(sizeof(struct sdshdr)));
o = hashTypeGetObject(o, &fieldobj);
} else {
if (o->type != REDIS_STRING) return NULL;
/* Every object that this function returns needs to have its refcount
* increased. sortCommand decreases it again. */
incrRefCount(o);
}
return o;
}
