fix dblink type bugs

src/sql/dblink/ob_dblink_utils.cpp

@@ -523,4 +523,57 @@ int ObDblinkCtxInSession::get_reverse_link(ObReverseLink *&reverse_dblink)
     LOG_DEBUG("succ to get reverse link from seesion", K(session_info_->get_sessid()), K(*reverse_dblink), KP(reverse_dblink));
   }
   return ret;
+}
+
+OB_SERIALIZE_MEMBER(ObParamPosIdx, pos_, idx_, type_value_);
+
+int ObLinkStmtParam::write(char *buf, int64_t buf_len, int64_t &pos, int64_t param_idx, int8_t type_value)
+{
+  /*
+   * we need 4 bytes for every const param:
+   * 1 byte:  '\0' for meta info flag. '\0' can not appear in any sql stmt fmt.
+   * 1 byte:  meta info type. now we used 0 to indicate const param.
+   * 2 bytes: uint16 for param index.
+   */
+  int ret = OB_SUCCESS;
+  if (buf_len - pos < PARAM_LEN) {
+    ret = OB_SIZE_OVERFLOW;
+    LOG_WARN("buffer is not enough", K(ret), K(buf_len), K(pos));
+  } else if (type_value < -1 || type_value > static_cast<int8_t>(ObObjType::ObMaxType)) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_WARN("invalid type_value", K(type_value), K(ret));
+  } else if (param_idx < 0 || param_idx > UINT16_MAX) {
+    ret = OB_NOT_SUPPORTED;
+    LOG_WARN("param count should be between 0 and UINT16_MAX", K(ret), K(param_idx));
+    LOG_USER_ERROR(OB_NOT_SUPPORTED, "param count not in the range 0 - UINT16_MAX");
+  } else {
+    buf[pos++] = 0;   // meta flag.
+    buf[pos++] = type_value;   // meta type.
+    *(uint16_t*)(buf + pos) = param_idx;
+    pos += sizeof(uint16_t);
+  }
+  return ret;
+}
+
+int ObLinkStmtParam::read_next(const char *buf, int64_t buf_len, int64_t &pos, int64_t &param_idx, int8_t &type_value)
+{
+  int ret = OB_SUCCESS;
+  const char *ch = buf + pos;
+  const char *buf_end = buf + buf_len - PARAM_LEN + 1;
+  param_idx = -1;
+  while (OB_SUCC(ret) && param_idx < 0 && ch < buf_end) {
+    if (0 != ch[0]) {
+      ch++;
+    } else {
+      type_value = static_cast<int8_t>(ch[1]);
+      if (type_value < -1 || type_value > static_cast<int8_t>(ObObjType::ObMaxType)) {
+        ret = OB_ERR_UNEXPECTED;
+        LOG_WARN("invalid type_value", K(type_value), K(ret));
+      } else {
+        param_idx = static_cast<int64_t>(*(uint16_t*)(ch + 2));
+      }
+    }
+  }
+  pos = ch - buf;
+  return ret;
 }