From 7b900a5dd120b20380a68bfa13b84b18e3b7e2a7 Mon Sep 17 00:00:00 2001
From: Shuduo Sang <sangshuduo@gmail.com>
Date: Fri, 10 Apr 2020 22:50:31 +0800
Subject: [PATCH] check null pointer in tscSql.c.

---
 src/client/src/tscSql.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 199b4150e8..f2a3cdcab0 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -329,7 +329,10 @@ int taos_num_fields(TAOS_RES *res) {
   }
 
   SFieldInfo *pFieldsInfo = &pQueryInfo->fieldsInfo;
-  return (pFieldsInfo->numOfOutputCols - pFieldsInfo->numOfHiddenCols);
+  if (pFieldsInfo)
+    return (pFieldsInfo->numOfOutputCols - pFieldsInfo->numOfHiddenCols);
+  else
+    return 0;
 }
 
 int taos_field_count(TAOS *taos) {
@@ -351,7 +354,11 @@ TAOS_FIELD *taos_fetch_fields(TAOS_RES *res) {
   if (pSql == NULL || pSql->signature != pSql) return 0;
 
   SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(&pSql->cmd, 0);
-  return pQueryInfo->fieldsInfo.pFields;
+
+  if (pQueryInfo)
+    return pQueryInfo->fieldsInfo.pFields;
+  else
+    return NULL;
 }
 
 int taos_retrieve(TAOS_RES *res) {
@@ -401,6 +408,9 @@ int taos_fetch_block_impl(TAOS_RES *res, TAOS_ROW *rows) {
   }
 
   SQueryInfo *pQueryInfo = tscGetQueryInfoDetail(pCmd, 0);
+  if (pQueryInfo == NULL)
+    return 0;
+
   for (int i = 0; i < pQueryInfo->fieldsInfo.numOfOutputCols; ++i) {
     pRes->tsrow[i] = TSC_GET_RESPTR_BASE(pRes, pQueryInfo, i);
   }
-- 
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