cherry-pick bug fix in 3.1

deps/oblib/src/lib/charset/ob_charset.cpp

@@ -2397,5 +2397,21 @@ int ObStringScanner::next_character(ObString& encoding, int32_t& wchar)
   return ret;
 }
 
-}  // namespace common
-}  // namespace oceanbase
+bool ObStringScanner::next_character(ObString &encoding, int32_t &wchar, int &ret)
+{
+  bool has_next = false;
+  ret = next_character(encoding, wchar);
+  if (OB_ITER_END == ret) {
+    has_next = false;
+    ret = OB_SUCCESS;
+  } else if (OB_SUCC(ret)) {
+    has_next = true;
+  } else {
+    LOG_WARN("fail to get next character", K(ret), K(*this));
+    has_next = false;
+  }
+  return has_next;
+}
+
+} // namespace common
+} // namespace oceanbase

deps/oblib/src/lib/charset/ob_charset.h

@@ -93,6 +93,8 @@ private:
   virtual ~ObCharset(){};
 
 public:
+  static const int32_t MAX_MB_LEN = 5;
+  static const int32_t MIN_MB_LEN = 1;
   static const int64_t CHARSET_WRAPPER_COUNT = 2;
   static const int64_t COLLATION_WRAPPER_COUNT = 3;
 
@@ -306,7 +308,8 @@ public:
   ObStringScanner(const ObString& str, common::ObCollationType collation_type)
       : str_(str), collation_type_(collation_type)
   {}
-  int next_character(ObString& encoding, int32_t& wchar);
+  int next_character(ObString &encoding, int32_t &wchar);
+  bool next_character(ObString &encoding, int32_t &wchar, int &ret);
   TO_STRING_KV(K_(str), K_(collation_type));
 
 private:

deps/oblib/src/lib/timezone/ob_time_convert.cpp

@@ -3183,16 +3183,13 @@ int ObTimeConverter::str_to_ob_time_oracle_dfm(
     // 2. set default value for ob_time
     if (OB_SUCC(ret)) {
       int64_t utc_curr_time = ObTimeUtility::current_time();
+      int64_t utc_curr_time_copy = utc_curr_time;
       int32_t cur_date = 0;
       if (OB_ISNULL(cvrt_ctx.tz_info_)) {
         ret = OB_ERR_UNEXPECTED;
         LOG_WARN("session timezone info is null", K(ret));
-      } else if (sub_timezone_offset(*(cvrt_ctx.tz_info_),
-                     ObString(),
-                     utc_curr_time,
-                     session_tz_offset,
-                     session_tz_id,
-                     session_tran_type_id)) {
+      } else if (sub_timezone_offset(*(cvrt_ctx.tz_info_), ObString(),
+                                     utc_curr_time_copy, session_tz_offset, session_tz_id, session_tran_type_id)) {
         LOG_WARN("get session timezone offset failed", K(ret));
       } else if (OB_FAIL(datetime_to_date(utc_curr_time, cvrt_ctx.tz_info_, cur_date))) {
         LOG_WARN("timestamp to date failed", K(ret));