Fix regressions from RESP3 changes in commit c8304b099d82dba4da35f4cfaa99595bcdb46d1a

Former-commit-id: c5cbb77fc7e3b2b5124b9432e144d8c74190c755

src/networking.cpp

@@ -839,8 +839,11 @@ void addReplyNullCore(client *c, bool fAsync) {
     }
 }
 
-void addReplyNull(client *c) {
+void addReplyNull(client *c, robj_roptr objOldProtocol) {
-    addReplyNullCore(c, false);
+    if (c->resp < 3 && objOldProtocol != nullptr)
+        addReply(c, objOldProtocol);
+    else
+        addReplyNullCore(c, false);
 }
 
 void addReplyNullAsync(client *c) {
@@ -932,7 +935,10 @@ void addReplyBulkSdsAsync(client *c, sds s) {
 /* Add a C null term string as bulk reply */
 void addReplyBulkCStringCore(client *c, const char *s, bool fAsync) {
     if (s == NULL) {
-        addReplyNullCore(c,fAsync);
+        if (c->resp < 3)
+            addReplyCore(c,shared.nullbulk, fAsync);
+        else
+            addReplyNullCore(c,fAsync);
     } else {
         addReplyBulkCBufferCore(c,s,strlen(s),fAsync);
     }
@@ -2540,7 +2546,7 @@ NULL
         if (c->name)
             addReplyBulk(c,c->name);
         else
-            addReplyNull(c);
+            addReplyNull(c, shared.nullbulk);
     } else if (!strcasecmp((const char*)ptrFromObj(c->argv[1]),"pause") && c->argc == 3) {
         long long duration;
 

src/object.cpp

@@ -1341,7 +1341,7 @@ NULL
             }
         }
         if ((de = dictFind(c->db->pdict,ptrFromObj(c->argv[2]))) == NULL) {
-            addReplyNull(c);
+            addReplyNull(c, shared.nullbulk);
             return;
         }
         size_t usage = objectComputeSize((robj*)dictGetVal(de),samples);

src/pubsub.cpp

@@ -84,7 +84,7 @@ void addReplyPubsubUnsubscribed(client *c, robj *channel) {
     if (channel)
         addReplyBulk(c,channel);
     else
-        addReplyNull(c);
+        addReplyNull(c, shared.nullbulk);
     addReplyLongLong(c,clientSubscriptionsCount(c));
 }
 
@@ -112,7 +112,7 @@ void addReplyPubsubPatUnsubscribed(client *c, robj *pattern) {
     if (pattern)
         addReplyBulk(c,pattern);
     else
-        addReplyNull(c);
+        addReplyNull(c, shared.nullbulk);
     addReplyLongLong(c,clientSubscriptionsCount(c));
 }
 

src/server.cpp

@@ -2174,6 +2174,8 @@ void createSharedObjects(void) {
     shared.ok = createObject(OBJ_STRING,sdsnew("+OK\r\n"));
     shared.err = createObject(OBJ_STRING,sdsnew("-ERR\r\n"));
     shared.emptybulk = createObject(OBJ_STRING,sdsnew("$0\r\n\r\n"));
+    shared.emptymultibulk = createObject(OBJ_STRING,sdsnew("*0\r\n"));
+    shared.nullbulk = createObject(OBJ_STRING,sdsnew("$0\r\n\r\n"));
     shared.czero = createObject(OBJ_STRING,sdsnew(":0\r\n"));
     shared.cone = createObject(OBJ_STRING,sdsnew(":1\r\n"));
     shared.emptyarray = createObject(OBJ_STRING,sdsnew("*0\r\n"));

src/server.h

@@ -978,7 +978,7 @@ struct moduleLoadQueueEntry {
 };
 
 struct sharedObjectsStruct {
-    robj *crlf, *ok, *err, *emptybulk, *czero, *cone, *pong, *space,
+    robj *crlf, *ok, *err, *emptybulk, *emptymultibulk, *nullbulk, *czero, *cone, *pong, *space,
     *colon, *queued, *null[4], *nullarray[4],
     *emptyarray, *wrongtypeerr, *nokeyerr, *syntaxerr, *sameobjecterr,
     *outofrangeerr, *noscripterr, *loadingerr, *slowscripterr, *bgsaveerr,
@@ -1701,7 +1701,7 @@ void acceptHandler(aeEventLoop *el, int fd, void *privdata, int mask);
 void acceptTcpHandler(aeEventLoop *el, int fd, void *privdata, int mask);
 void acceptUnixHandler(aeEventLoop *el, int fd, void *privdata, int mask);
 void readQueryFromClient(aeEventLoop *el, int fd, void *privdata, int mask);
-void addReplyNull(client *c);
+void addReplyNull(client *c, robj_roptr objOldProtocol = nullptr);
 void addReplyNullArray(client *c);
 void addReplyBool(client *c, int b);
 void addReplyVerbatim(client *c, const char *s, size_t len, const char *ext);

src/t_list.cpp

@@ -331,7 +331,7 @@ void lindexCommand(client *c) {
             addReplyBulk(c,value);
             decrRefCount(value);
         } else {
-            addReplyNull(c);
+            addReplyNull(c,shared.nullbulk);
         }
     } else {
         serverPanic("Unknown list encoding");
@@ -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);
+        addReplyNull(c,shared.emptymultibulk);
         return;
     }
     if (end >= llen) end = llen-1;

src/t_zset.cpp

@@ -2439,7 +2439,7 @@ 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);
+        addReplyNull(c,shared.emptymultibulk);
         return;
     }
     if (end >= llen) end = llen-1;