RESP3: fix cases of NULL reported instead of empty aggregate.

src/server.c

@@ -2161,6 +2161,16 @@ void createSharedObjects(void) {
     shared.nullarray[2] = createObject(OBJ_STRING,sdsnew("*-1\r\n"));
     shared.nullarray[3] = createObject(OBJ_STRING,sdsnew("_\r\n"));
 
+    shared.emptymap[0] = NULL;
+    shared.emptymap[1] = NULL;
+    shared.emptymap[2] = createObject(OBJ_STRING,sdsnew("*0\r\n"));
+    shared.emptymap[3] = createObject(OBJ_STRING,sdsnew("%0\r\n"));
+
+    shared.emptyset[0] = NULL;
+    shared.emptyset[1] = NULL;
+    shared.emptyset[2] = createObject(OBJ_STRING,sdsnew("*0\r\n"));
+    shared.emptyset[3] = createObject(OBJ_STRING,sdsnew("~0\r\n"));
+
     for (j = 0; j < PROTO_SHARED_SELECT_CMDS; j++) {
         char dictid_str[64];
         int dictid_len;

src/server.h

@@ -897,7 +897,7 @@ struct moduleLoadQueueEntry {
 
 struct sharedObjectsStruct {
     robj *crlf, *ok, *err, *emptybulk, *czero, *cone, *pong, *space,
-    *colon, *queued, *null[4], *nullarray[4],
+    *colon, *queued, *null[4], *nullarray[4], *emptymap[4], *emptyset[4],
     *emptyarray, *wrongtypeerr, *nokeyerr, *syntaxerr, *sameobjecterr,
     *outofrangeerr, *noscripterr, *loadingerr, *slowscripterr, *bgsaveerr,
     *masterdownerr, *roslaveerr, *execaborterr, *noautherr, *noreplicaserr,

src/t_hash.c

@@ -772,8 +772,8 @@ void genericHgetallCommand(client *c, int flags) {
     hashTypeIterator *hi;
     int length, count = 0;
 
-    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.null[c->resp])) == NULL
+    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptymap[c->resp]))
-        || checkType(c,o,OBJ_HASH)) return;
+        == NULL || checkType(c,o,OBJ_HASH)) return;
 
     /* We return a map if the user requested keys and values, like in the
      * HGETALL case. Otherwise to use a flat array makes more sense. */

src/t_list.c

@@ -402,7 +402,7 @@ void lrangeCommand(client *c) {
     if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != C_OK) ||
         (getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != C_OK)) return;
 
-    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.null[c->resp])) == NULL
+    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptyarray)) == NULL
          || checkType(c,o,OBJ_LIST)) return;
     llen = listTypeLength(o);
 
@@ -414,7 +414,7 @@ void lrangeCommand(client *c) {
     /* Invariant: start >= 0, so this test will be true when end < 0.
      * The range is empty when start > end or start >= length. */
     if (start > end || start >= llen) {
-        addReplyNull(c);
+        addReply(c,shared.emptyarray);
         return;
     }
     if (end >= llen) end = llen-1;

src/t_set.c

@@ -418,10 +418,10 @@ void spopWithCountCommand(client *c) {
     if ((set = lookupKeyWriteOrReply(c,c->argv[1],shared.null[c->resp]))
         == NULL || checkType(c,set,OBJ_SET)) return;
 
-    /* If count is zero, serve an empty multibulk ASAP to avoid special
+    /* If count is zero, serve an empty set ASAP to avoid special
      * cases later. */
     if (count == 0) {
-        addReplyNull(c);
+        addReply(c,shared.emptyset[c->resp]);
         return;
     }
 
@@ -632,13 +632,13 @@ void srandmemberWithCountCommand(client *c) {
         uniq = 0;
     }
 
-    if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.null[c->resp]))
+    if ((set = lookupKeyReadOrReply(c,c->argv[1],shared.emptyset[c->resp]))
         == NULL || checkType(c,set,OBJ_SET)) return;
     size = setTypeSize(set);
 
     /* If count is zero, serve it ASAP to avoid special cases later. */
     if (count == 0) {
-        addReplyNull(c);
+        addReply(c,shared.emptyset[c->resp]);
         return;
     }
 
@@ -813,7 +813,7 @@ void sinterGenericCommand(client *c, robj **setkeys,
                 }
                 addReply(c,shared.czero);
             } else {
-                addReplyNull(c);
+                addReply(c,shared.emptyset[c->resp]);
             }
             return;
         }

src/t_zset.c

@@ -2426,7 +2426,7 @@ void zrangeGenericCommand(client *c, int reverse) {
         return;
     }
 
-    if ((zobj = lookupKeyReadOrReply(c,key,shared.null[c->resp])) == NULL
+    if ((zobj = lookupKeyReadOrReply(c,key,shared.emptyarray)) == NULL
          || checkType(c,zobj,OBJ_ZSET)) return;
 
     /* Sanitize indexes. */
@@ -2438,7 +2438,7 @@ void zrangeGenericCommand(client *c, int reverse) {
     /* Invariant: start >= 0, so this test will be true when end < 0.
      * The range is empty when start > end or start >= length. */
     if (start > end || start >= llen) {
-        addReplyNull(c);
+        addReply(c,shared.emptyarray);
         return;
     }
     if (end >= llen) end = llen-1;
@@ -2574,7 +2574,7 @@ void genericZrangebyscoreCommand(client *c, int reverse) {
     }
 
     /* Ok, lookup the key and get the range */
-    if ((zobj = lookupKeyReadOrReply(c,key,shared.null[c->resp])) == NULL ||
+    if ((zobj = lookupKeyReadOrReply(c,key,shared.emptyarray)) == NULL ||
         checkType(c,zobj,OBJ_ZSET)) return;
 
     if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
@@ -2594,7 +2594,7 @@ void genericZrangebyscoreCommand(client *c, int reverse) {
 
         /* No "first" element in the specified interval. */
         if (eptr == NULL) {
-            addReplyNull(c);
+            addReply(c,shared.emptyarray);
             return;
         }
 
@@ -2661,7 +2661,7 @@ void genericZrangebyscoreCommand(client *c, int reverse) {
 
         /* No "first" element in the specified interval. */
         if (ln == NULL) {
-            addReplyNull(c);
+            addReply(c,shared.emptyarray);
             return;
         }
 
@@ -2919,7 +2919,7 @@ void genericZrangebylexCommand(client *c, int reverse) {
     }
 
     /* Ok, lookup the key and get the range */
-    if ((zobj = lookupKeyReadOrReply(c,key,shared.null[c->resp])) == NULL ||
+    if ((zobj = lookupKeyReadOrReply(c,key,shared.emptyarray)) == NULL ||
         checkType(c,zobj,OBJ_ZSET))
     {
         zslFreeLexRange(&range);
@@ -2942,7 +2942,7 @@ void genericZrangebylexCommand(client *c, int reverse) {
 
         /* No "first" element in the specified interval. */
         if (eptr == NULL) {
-            addReplyNull(c);
+            addReply(c,shared.emptyarray);
             zslFreeLexRange(&range);
             return;
         }
@@ -3006,7 +3006,7 @@ void genericZrangebylexCommand(client *c, int reverse) {
 
         /* No "first" element in the specified interval. */
         if (ln == NULL) {
-            addReplyNull(c);
+            addReply(c,shared.emptyarray);
             zslFreeLexRange(&range);
             return;
         }
@@ -3160,7 +3160,7 @@ void genericZpopCommand(client *c, robj **keyv, int keyc, int where, int emitkey
 
     /* No candidate for zpopping, return empty. */
     if (!zobj) {
-        addReplyNull(c);
+        addReply(c,shared.emptyarray);
         return;
     }