/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifdef __linux__
# include <sys/timex.h>
#endif


size_t
libpatch_create_timestamp_now(char *buf, size_t bufsize, signed frac, int zone, enum libpatch_style style)
{
	struct timespec ts;
#ifdef __linux__
	struct timex timex;
	struct tm tm;
	int r;
#endif

	if (frac < 0) {
		if (clock_gettime(CLOCK_REALTIME, &ts)) {
			frac = 9;
		} else {
			frac = 0;
			while (ts.tv_nsec < 1000000000L) {
				ts.tv_nsec *= 10;
				frac += 1;
			}
		}
	}

#ifdef __linux__
	memset(&timex, 0, sizeof(timex));
	if (frac > 6)
		timex.status = ADJ_NANO;
	r = adjtimex(&timex);
	if (r == -1) {
		if (errno == ENOSYS)
			goto fallback;
		return 0;
	}

	if (timex.time.tv_sec % (24 * 60 * 60) == 0) {
		if (r == TIME_INS) {
			timex.time.tv_sec -= 1;
			if (!localtime_r(&timex.time.tv_sec, &tm))
				return 0;
			tm.tm_sec += 1;
		} else if (r == TIME_DEL) {
			timex.time.tv_sec += 1;
			if (!localtime_r(&timex.time.tv_sec, &tm))
				return 0;
		} else {
			if (!localtime_r(&timex.time.tv_sec, &tm))
				return 0;
		}
	} else if (r == TIME_OOP) {
		if (!localtime_r(&timex.time.tv_sec, &tm))
			return 0;
		tm.tm_sec += 1;
	} else {
		if (!localtime_r(&timex.time.tv_sec, &tm))
			return 0;
	}

	return libpatch_create_timestamp(buf, bufsize, &tm, (uintmax_t)timex.time.tv_usec,
	                                 frac > 6 ? 9U : 6U, (unsigned)frac, zone, style);

fallback:
#endif

	if (clock_gettime(CLOCK_REALTIME, &ts))
		return 0;
	return libpatch_create_timestamp_ts(buf, bufsize, &ts, (unsigned)frac, zone, style);
}