Merge pull request #7632 from taosdata/fix/TD-6356

[TD-6356]<fix>: Fix the crash in TS-187

src/tsdb/src/tsdbRead.c

@@ -3480,8 +3480,8 @@ void filterPrepare(void* expr, void* param) {
         SArray *arr = (SArray *)(pCond->arr);
         for (size_t i = 0; i < taosArrayGetSize(arr); i++) {
           char* p = taosArrayGetP(arr, i);
-          strtolower(varDataVal(p), varDataVal(p));
-          taosHashPut(pObj, varDataVal(p),varDataLen(p), &dummy, sizeof(dummy));
+          strntolower_s(varDataVal(p), varDataVal(p), varDataLen(p));
+          taosHashPut(pObj, varDataVal(p), varDataLen(p), &dummy, sizeof(dummy));
         }
      } else {
        buildFilterSetFromBinary((void **)&pObj, pCond->pz, pCond->nLen);

src/util/inc/tutil.h

@@ -32,6 +32,7 @@ char *  strnchr(char *haystack, char needle, int32_t len, bool skipquote);
 char ** strsplit(char *src, const char *delim, int32_t *num);
 char *  strtolower(char *dst, const char *src);
 char *  strntolower(char *dst, const char *src, int32_t n);
+char *  strntolower_s(char *dst, const char *src, int32_t n);
 int64_t strnatoi(char *num, int32_t len);
 char *  strbetween(char *string, char *begin, char *end);
 char *  paGetToken(char *src, char **token, int32_t *tokenLen);

src/util/src/tutil.c

@@ -224,6 +224,26 @@ char* strntolower(char *dst, const char *src, int32_t n) {
   return dst;
 }
 
+char* strntolower_s(char *dst, const char *src, int32_t n) {
+  char *p = dst, c;
+
+  assert(dst != NULL);
+  if (n == 0) {
+    return NULL;
+  }
+
+  while (n-- > 0) {
+    c = *src;
+    if (c >= 'A' && c <= 'Z') {
+      c -= 'A' - 'a';
+    }
+    *p++ = c;
+    src++;
+  }
+
+  return dst;
+}
+
 char *paGetToken(char *string, char **token, int32_t *tokenLen) {
   char quote = 0;