fix: fix issues reported by coverity scan

examples/c/asyncdemo.c

@@ -92,7 +92,7 @@ int main(int argc, char *argv[])
   }
 
   // a simple way to parse input parameters
-  if (argc >= 3) strcpy(db, argv[2]);
+  if (argc >= 3) strncpy(db, argv[2], sizeof(db) - 1);
   if (argc >= 4) points = atoi(argv[3]);
   if (argc >= 5) numOfTables = atoi(argv[4]);
 

source/client/src/clientMsgHandler.c

@@ -456,12 +456,13 @@ static int32_t buildShowVariablesRsp(SArray* pVars, SRetrieveTableRsp** pRsp) {
   (*pRsp)->numOfCols = htonl(SHOW_VARIABLES_RESULT_COLS);
 
   int32_t len = blockEncode(pBlock, (*pRsp)->data, SHOW_VARIABLES_RESULT_COLS);
+  blockDataDestroy(pBlock);
+
   if(len != rspSize - sizeof(SRetrieveTableRsp)){
     uError("buildShowVariablesRsp error, len:%d != rspSize - sizeof(SRetrieveTableRsp):%" PRIu64, len, (uint64_t) (rspSize - sizeof(SRetrieveTableRsp)));
     return TSDB_CODE_TSC_INVALID_INPUT;
   }
 
-  blockDataDestroy(pBlock);
   return TSDB_CODE_SUCCESS;
 }
 

source/libs/catalog/src/ctgCache.c

@@ -493,11 +493,9 @@ int32_t ctgCopyTbMeta(SCatalog *pCtg, SCtgTbMetaCtx *ctx, SCtgDBCache **pDb, SCt
 
   //ctgReleaseTbMetaToCache(pCtg, dbCache, tbCache);
 
-  if (tbCache) {
-    CTG_UNLOCK(CTG_READ, &tbCache->metaLock);
-    taosHashRelease(dbCache->tbCache, tbCache);
-    *pTb = NULL;
-  }
+  CTG_UNLOCK(CTG_READ, &tbCache->metaLock);
+  taosHashRelease(dbCache->tbCache, tbCache);
+  *pTb = NULL;
   
   ctgDebug("Got ctb %s meta from cache, will continue to get its stb meta, type:%d, dbFName:%s", ctx->pName->tname,
            ctx->tbInfo.tbType, dbFName);
@@ -1554,8 +1552,8 @@ int32_t ctgWriteTbMetaToCache(SCatalog *pCtg, SCtgDBCache *dbCache, char *dbFNam
     SCtgTbCache cache = {0};
     cache.pMeta = meta;
     if (taosHashPut(dbCache->tbCache, tbName, strlen(tbName), &cache, sizeof(SCtgTbCache)) != 0) {
-      taosMemoryFree(meta);
       ctgError("taosHashPut new tbCache failed, dbFName:%s, tbName:%s, tbType:%d", dbFName, tbName, meta->tableType);
+      taosMemoryFree(meta);
       CTG_ERR_RET(TSDB_CODE_OUT_OF_MEMORY);
     }
 

source/libs/qworker/src/qworker.c

@@ -847,6 +847,9 @@ _return:
       qwBuildAndSendFetchRsp(qwMsg->msgType + 1, &qwMsg->connInfo, rsp, dataLen, code);
       QW_TASK_DLOG("%s send, handle:%p, code:%x - %s, dataLen:%d", TMSG_INFO(qwMsg->msgType + 1),
                    qwMsg->connInfo.handle, code, tstrerror(code), dataLen);
+    } else {
+      qwFreeFetchRsp(rsp);
+      rsp = NULL;
     }
   }
 
@@ -1217,7 +1220,7 @@ void qWorkerStopAllTasks(void *qWorkerMgmt) {
       QW_UPDATE_RSP_CODE(ctx, TSDB_CODE_VND_STOPPED);
       QW_SET_EVENT_RECEIVED(ctx, QW_EVENT_DROP);    
     } else {
-      qwDropTask(QW_FPARAMS());
+      (void)qwDropTask(QW_FPARAMS());
     }
 
     QW_UNLOCK(QW_WRITE, &ctx->lock);