usr/src/usr.sbin/sendmail/src/arpadate.c

/*
 * Copyright (c) 1983 Eric P. Allman
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 lint
static char sccsid[] = "@(#)arpadate.c  5.11 (Berkeley) 6/1/90";
#endif /* not lint */

# include "conf.h"
# include <time.h>
# include <sys/types.h>
# include "useful.h"

/*
**  ARPADATE -- Create date in ARPANET format
**
**      Parameters:
**              ud -- unix style date string.  if NULL, one is created.
**
**      Returns:
**              pointer to an ARPANET date field
**
**      Side Effects:
**              none
**
**      WARNING:
**              date is stored in a local buffer -- subsequent
**              calls will overwrite.
**
**      Bugs:
**              Timezone is computed from local time, rather than
**              from whereever (and whenever) the message was sent.
**              To do better is very hard.
**
**              Some sites are now inserting the timezone into the
**              local date.  This routine should figure out what
**              the format is and work appropriately.
*/

char *
arpadate(ud)
        register char *ud;
{
        register char *p;
        register char *q;
        register int off;
        register int i;
        register struct tm *lt;
        time_t t;
        struct tm gmt;
        static char b[40];
        extern struct tm *localtime(), *gmtime();
        extern char *ctime();
        extern time_t time();

        /*
        **  Get current time.
        **      This will be used if a null argument is passed and
        **      to resolve the timezone.
        */

        (void) time(&t);
        if (ud == NULL)
                ud = ctime(&t);

        /*
        **  Crack the UNIX date line in a singularly unoriginal way.
        */

        q = b;

        p = &ud[0];             /* Mon */
        *q++ = *p++;
        *q++ = *p++;
        *q++ = *p++;
        *q++ = ',';
        *q++ = ' ';

        p = &ud[8];             /* 16 */
        if (*p == ' ')
                p++;
        else
                *q++ = *p++;
        *q++ = *p++;
        *q++ = ' ';

        p = &ud[4];             /* Sep */
        *q++ = *p++;
        *q++ = *p++;
        *q++ = *p++;
        *q++ = ' ';

        p = &ud[22];            /* 79 */
        *q++ = *p++;
        *q++ = *p++;
        *q++ = ' ';

        p = &ud[11];            /* 01:03:52 */
        for (i = 8; i > 0; i--)
                *q++ = *p++;

        /*
         * should really get the timezone from the time in "ud" (which
         * is only different if a non-null arg was passed which is different
         * from the current time), but for all practical purposes, returning
         * the current local zone will do (its all that is ever needed).
         */
        gmt = *gmtime(&t);
        lt = localtime(&t);

        off = (lt->tm_hour - gmt.tm_hour) * 60 + lt->tm_min - gmt.tm_min;

        /* assume that offset isn't more than a day ... */
        if (lt->tm_year < gmt.tm_year)
                off -= 24 * 60;
        else if (lt->tm_year > gmt.tm_year)
                off += 24 * 60;
        else if (lt->tm_yday < gmt.tm_yday)
                off -= 24 * 60;
        else if (lt->tm_yday > gmt.tm_yday)
                off += 24 * 60;

        *q++ = ' ';
        if (off == 0) {
                *q++ = 'G';
                *q++ = 'M';
                *q++ = 'T';
        } else {
                if (off < 0) {
                        off = -off;
                        *q++ = '-';
                } else
                        *q++ = '+';

                if (off >= 24*60)               /* should be impossible */
                        off = 23*60+59;         /* if not, insert silly value */

                *q++ = (off / 600) + '0';
                *q++ = (off / 60) % 10 + '0';
                off %= 60;
                *q++ = (off / 10) + '0';
                *q++ = (off % 10) + '0';
        }
        *q = '\0';

        return (b);
}