adtools/clib2

/*
 * $Id: time_mktime.c,v 1.11 2015-06-26 11:22:00 obarthel Exp $
 *
 * :ts=4
 *
 * Portable ISO 'C' (1994) runtime library for the Amiga computer
 * Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Neither the name of Olaf Barthel nor the names of contributors
 *     may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _STDLIB_NULL_POINTER_CHECK_H
#include "stdlib_null_pointer_check.h"
#endif /* _STDLIB_NULL_POINTER_CHECK_H */

/****************************************************************************/

#ifndef _TIME_HEADERS_H
#include "time_headers.h"
#endif /* _TIME_HEADERS_H */

#ifndef _LOCALE_HEADERS_H
#include "locale_headers.h"
#endif /* _LOCALE_HEADERS_H */

/****************************************************************************/

time_t
mktime(struct tm *tm)
{
    DECLARE_UTILITYBASE();
    struct ClockData clock_data;
    ULONG seconds;
    time_t result = (time_t)-1;
    LONG combined_seconds;
    int month, year;

    ENTER();

    assert( tm != NULL );
    assert( UtilityBase != NULL );

    #if defined(CHECK_FOR_NULL_POINTERS)
    {
        if(tm == NULL)
        {
            SHOWMSG("invalid tm parameter");

            __set_errno(EFAULT);
            goto out;
        }
    }
    #endif /* CHECK_FOR_NULL_POINTERS */

    /* Normalize the year and month. */
    year = tm->tm_year + 1900;
    month = tm->tm_mon + 1;

    if(month < 0 || month > 12)
    {
        int y;

        y = month / 12;

        month -= y * 12;
        year += y;
    }

    if(month < 1)
    {
        month += 12;
        year -= 1;
    }

    /* The year must be valid. Amiga time begins with January 1st, 1978. */
    if(year < 1978)
    {
        SHOWVALUE(year);
        SHOWMSG("invalid year");
        goto out;
    }

    /* Convert the first day of the month in the given year
       into the corresponding number of seconds. */
    memset(&clock_data, 0, sizeof(clock_data));
    
    clock_data.mday        = 1;
    clock_data.month    = month;
    clock_data.year        = year;

    seconds = Date2Amiga(&clock_data);

    /* Put the combined number of seconds involved together,
       covering the seconds/minutes/hours of the day as well
       as the number of days of the month. This will be added
       to the number of seconds for the date. */
    combined_seconds = tm->tm_sec + 60 * (tm->tm_min + 60 * (tm->tm_hour + 24 * (tm->tm_mday-1)));
    
    /* If the combined number of seconds is negative, adding it
     * to the number of seconds for the date should not produce
     * a negative value.
     */
    if(combined_seconds < 0 && seconds < (ULONG)(-combined_seconds))
    {
        SHOWVALUE(seconds);
        SHOWVALUE(combined_seconds);
        SHOWMSG("invalid combined number of seconds");
        goto out;
    }

    seconds += combined_seconds;

    __locale_lock();

    /* The data in 'struct tm *tm' was given in local time. We need
       to convert the result into UTC. */
    if(__default_locale != NULL)
        seconds += 60 * __default_locale->loc_GMTOffset;

    __locale_unlock();

    /* Adjust for the difference between the Unix and the
       AmigaOS epochs, which differ by 8 years. */
    result = seconds + UNIX_TIME_OFFSET;

    /* Finally, normalize the provided time and date information. */
    localtime_r(&result, tm);

 out:

    RETURN(result);
    return(result);
}