eve/fileinfo: don't alloc filename during logging

src/output-json-file.c

@@ -145,10 +145,10 @@ json_t *JsonBuildFileInfoRecord(const Packet *p, const File *ff,
         return NULL;
     }
 
-    char *s = BytesToString(ff->name, ff->name_len);
-    json_object_set_new(fjs, "filename", SCJsonString(s));
-    if (s != NULL)
-        SCFree(s);
+    size_t filename_size = ff->name_len * 2 + 1;
+    char filename_string[filename_size];
+    BytesToStringBuffer(ff->name, ff->name_len, filename_string, filename_size);
+    json_object_set_new(fjs, "filename", SCJsonString(filename_string));
 #ifdef HAVE_MAGIC
     if (ff->magic)
         json_object_set_new(fjs, "magic", json_string((char *)ff->magic));