__must_check int mark_fd_nonblocking(int fd);
__must_check int mark_fd_blocking(int fd);
void para_fd_set(int fd, fd_set *fds, int *max_fileno);
-__must_check int para_fgets(char *line, int size, FILE *f);
int para_mmap(size_t length, int prot, int flags, int fd, void *map);
int para_open(const char *path, int flags, mode_t mode);
int para_mkdir(const char *path, mode_t mode);