fix core when tag is emptyv4.5.6c

2 files changed, 6 insertions, 3 deletions

diff --git a/src/exporter/cjson_exporter.c b/src/exporter/cjson_exporter.c
index c9a410d..206f7b1 100644
--- a/src/exporter/cjson_exporter.c
+++ b/src/exporter/cjson_exporter.c
@@ -379,6 +379,9 @@ void write_delta_to_json(struct fieldstat_json_exporter *exporter, struct cellwi
 {
     // for every tag_field_pair, get the tag json string
     const char *tag_json = json_writer_unwrap(tag_field_pair->cjson_tags);
+    if (tag_json == NULL) {
+        tag_json = "\a\t\a"; // just a dummy string
+    }
     for (int j = 0; j < tag_field_pair->n_metric; j++) {
         if (tag_field_pair->metric_pairs[j]->type != TAG_INTEGER) { // only counter type need to write delta
             continue;
diff --git a/test/test_easy_fs.cpp b/test/test_easy_fs.cpp
index 0595593..d3f45b7 100644
--- a/test/test_easy_fs.cpp
+++ b/test/test_easy_fs.cpp
@@ -42,15 +42,15 @@ TEST(test_easy_fieldstat, output_to_buff)
 
 TEST(test_easy_fieldstat, output_to_buff_with_delta)
 {
-    struct fieldstat_easy *fse = fieldstat_easy_new(10, NULL, &TEST_TAG_STRING, 1);
+    struct fieldstat_easy *fse = fieldstat_easy_new(1, NULL, NULL, 0);
     fieldstat_easy_enable_delta_in_active_output(fse);
     fieldstat_easy_register_counter(fse, "metric counter");
-    fieldstat_easy_counter_incrby(fse, 0, 0, &TEST_TAG_INT, 1, 1);
+    fieldstat_easy_counter_incrby(fse, 0, 0, NULL, 0, 1);
     char *buff = NULL;
     size_t buff_len = 0;
     fieldstat_easy_output(fse, &buff, &buff_len);
     free(buff);
-    fieldstat_easy_counter_incrby(fse, 0, 0, &TEST_TAG_INT, 1, 1);
+    fieldstat_easy_counter_incrby(fse, 0, 0, NULL, 0, 1);
     fieldstat_easy_output(fse, &buff, &buff_len);
 
     cJSON *root = cJSON_Parse(buff);