#ifndef CUTILS_H#define CUTILS_H #if defined __GNUC__#define UNUSED_ATTR __attribute__ ((unused))#if !defined __clang__#define NO_OPTIMIZE_ATTR __attribute__ ((optimize ("O0")))#else#define NO_OPTIMIZE_ATTR __attribute__ ((optnone))#endif#define GCC_FMT_ATTR(a, b) __attribute__ ((format (printf, a, b)))#else#error Stringent C compiler requirements not satisfied#endif extern _Noreturn void GCC_FMT_ATTR (3, 4)    err (int errno_val, int exitcode, const char *fmt, ...);extern _Noreturn void GCC_FMT_ATTR (2, 3)    errx (int exitcode, const char *fmt, ...);extern void *parse_pointer (const char *cap, const char *s);extern double now (void);extern void fmt_linkn (char *s, const char *c, unsigned int l, int n); #endif