void *
xrealloc (void *ptr, size_t size);
+FILE *
+xfopen (const char *path, const char *mode);
+
FILE *
xfdopen (int filedes, const char *mode);
void
-xfreopen (const char *path, const char *mode, FILE *stream);
+xdup2 (int oldfd, int newfd);
char *
xstrdup (const char *s);