연결리스트에서 포인터 교환으로 swap할 때..

//링크드리스트에 들어있는자료를 파일이름순으로 정렬
void sort_list(FILEINFO *list_head)
{	
	FILEINFO *tmp_list_left;
	FILEINFO *tmp_list_right;
	FILEINFO *prev;
 
	prev = (FILEINFO*)malloc(sizeof(FILEINFO));
	prev->next = list_head;
 
	printf("%s\n", prev->next->filename);
 
	FILEINFO tmp_list;
	FILEINFO *tmp_listp;
 
	int change = 1;
 
 
	if(list_head == NULL || list_head->next == NULL)
		return ;
 
	tmp_list_left = list_head;
	//printf("%s\n", list_head->filename);
	tmp_list_right = list_head->next;
 
	while(change) {
		change = 0;	
		while(tmp_list_right!= NULL) {	
			//puts("================");
			if(flag_r) {
				if(strcmp(tmp_list_left->filename, tmp_list_right->filename) < 0) {
					//데이터 교환
					memcpy(&tmp_list, tmp_list_left, sizeof(FILEINFO));
					memcpy(tmp_list_left, tmp_list_right, sizeof(FILEINFO));
					memcpy(tmp_list_right, &tmp_list, sizeof(FILEINFO));
 
					//포인터 교환
					tmp_listp = tmp_list_left->next;
					tmp_list_left->next = tmp_list_right->next;
					tmp_list_right->next = tmp_listp;
					change = 1;
 
				}
				tmp_list_left = tmp_list_right;
				tmp_list_right = tmp_list_right->next;
 
			} 
			else {
				if(strcmp(tmp_list_left->filename,tmp_list_right->filename) >0 ) {	
 
					prev->next = tmp_list_left->next;
					tmp_list_left->next = tmp_list_right->next;
					tmp_list_right->next = tmp_list_left;
					change = 1;
				}
				if(change = 0) {
					tmp_list_left = tmp_list_right;
					tmp_list_right = tmp_list_left->next;
				}else {
					tmp_list_right = tmp_list_left->next;
				}
			}
		}
		prev ->next = list_head;
		printf("%s\n", list_head->filename);
		tmp_list_left = list_head;
		tmp_list_right = list_head->next;
	}
}
<//code>