// SPDX-License-Identifier: LGPL-2.0+
/* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Paul Eggert (eggert@twinsun.com). */

/*
 * dgb 10/02/98: ripped this from glibc source to help convert timestamps
 *               to unix time
 *     10/04/98: added new table-based lookup after seeing how ugly
 *               the gnu code is
 * blf 09/27/99: ripped out all the old code and inserted new table from
 *               John Brockmeyer (without leap second corrections)
 *               rewrote udf_stamp_to_time and fixed timezone accounting in
 *               udf_time_to_stamp.
 */

/*
 * We don't take into account leap seconds. This may be correct or incorrect.
 * For more NIST information (especially dealing with leap seconds), see:
 * http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm
 */

#include "udfdecl.h"

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/time.h>

void
udf_disk_stamp_to_time(struct timespec64 *dest, struct timestamp src)
{
        u16 typeAndTimezone = le16_to_cpu(src.typeAndTimezone);
        u16 year = le16_to_cpu(src.year);
        uint8_t type = typeAndTimezone >> 12;
        int16_t offset;

        if (type == 1) {
                offset = typeAndTimezone << 4;
                /* sign extent offset */
                offset = (offset >> 4);
                if (offset == -2047) /* unspecified offset */
                        offset = 0;
        } else
                offset = 0;

        dest->tv_sec = mktime64(year, src.month, src.day, src.hour, src.minute,
                        src.second);
        dest->tv_sec -= offset * 60;

        /*
         * Sanitize nanosecond field since reportedly some filesystems are
         * recorded with bogus sub-second values.
         */
        if (src.centiseconds < 100 && src.hundredsOfMicroseconds < 100 &&
            src.microseconds < 100) {
                dest->tv_nsec = 1000 * (src.centiseconds * 10000 +
                        src.hundredsOfMicroseconds * 100 + src.microseconds);
        } else {
                dest->tv_nsec = 0;
        }
}

void
udf_time_to_disk_stamp(struct timestamp *dest, struct timespec64 ts)
{
        time64_t seconds;
        int16_t offset;
        struct tm tm;

        offset = -sys_tz.tz_minuteswest;

        dest->typeAndTimezone = cpu_to_le16(0x1000 | (offset & 0x0FFF));

        seconds = ts.tv_sec + offset * 60;
        time64_to_tm(seconds, 0, &tm);
        dest->year = cpu_to_le16(tm.tm_year + 1900);
        dest->month = tm.tm_mon + 1;
        dest->day = tm.tm_mday;
        dest->hour = tm.tm_hour;
        dest->minute = tm.tm_min;
        dest->second = tm.tm_sec;
        dest->centiseconds = ts.tv_nsec / 10000000;
        dest->hundredsOfMicroseconds = (ts.tv_nsec / 1000 -
                                        dest->centiseconds * 10000) / 100;
        dest->microseconds = (ts.tv_nsec / 1000 - dest->centiseconds * 10000 -
                              dest->hundredsOfMicroseconds * 100);
}

/* EOF */