fix(userspace/engine): base64 format fix

Signed-off-by: Lorenzo Fontana <lo@linux.com>
Co-Authored-By: Leonardo Di Donato <leodidonato@gmail.com>

userspace/engine/formats.cpp

@@ -146,11 +146,13 @@ int falco_formats::format_event (lua_State *ls)
 	if(strcmp(source, "syscall") == 0)
 	{
 		try {
+			// This is "output"
 			s_formatters->tostring((sinsp_evt *) evt, sformat, &line);
 
 			if(s_json_output)
 			{
-				switch(s_inspector->get_buffer_format())
+				sinsp_evt::param_fmt cur_fmt = s_inspector->get_buffer_format();
+				switch(cur_fmt)
 				{
 					case sinsp_evt::PF_NORMAL:
 						s_inspector->set_buffer_format(sinsp_evt::PF_JSON);
@@ -171,15 +173,15 @@ int falco_formats::format_event (lua_State *ls)
 						// do nothing
 						break;
 				}
+				// This is output fields
 				s_formatters->tostring((sinsp_evt *) evt, sformat, &json_line);
 
 				// The formatted string might have a leading newline. If it does, remove it.
 				if (json_line[0] == '\n')
 				{
 					json_line.erase(0, 1);
 				}
-
-				s_inspector->set_buffer_format(sinsp_evt::PF_NORMAL);
+				s_inspector->set_buffer_format(cur_fmt);
 			}
 		}
 		catch (sinsp_exception& e)