void sysfail(const char *what, int errnoval) NONRETURNING;
void usageerr(const char *what, ...) NONRETURNPRINTFFORMAT(1,2);
void outerr(void) NONRETURNING;
-void setnonblock(int fd, int nonblock);
void *xmalloc(size_t sz);
char *xstrsave(const char *str);