extern int read_in_full(int fd, void *buf, size_t count);
extern int write_in_full(int fd, const void *buf, size_t count);
extern void write_or_die(int fd, const void *buf, size_t count);
extern int read_in_full(int fd, void *buf, size_t count);
extern int write_in_full(int fd, const void *buf, size_t count);
extern void write_or_die(int fd, const void *buf, size_t count);