sendmail/src/arpadate.c

	arpadate.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * Copyright (c) 1998-2001 Sendmail, Inc. and its suppliers.
 *  All rights reserved.
 * Copyright (c) 1983, 1995-1997 Eric P. Allman.  All rights reserved.
 * Copyright (c) 1988, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 *
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sendmail.h>

SM_RCSID("@(#)$Id: arpadate.c,v 8.28 2001/02/14 14:45:47 ca Exp $")

/*
**  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 wherever (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.
*/

#ifndef TZNAME_MAX
# define TZNAME_MAX 50  /* max size of timezone */
#endif /* ! TZNAME_MAX */

/* values for TZ_TYPE */
#define TZ_NONE     0   /* no character timezone support */
#define TZ_TM_NAME  1   /* use tm->tm_name */
#define TZ_TM_ZONE  2   /* use tm->tm_zone */
#define TZ_TZNAME   3   /* use tzname[] */
#define TZ_TIMEZONE 4   /* use timezone() */

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;
    char *tz;
    static char b[43 + TZNAME_MAX];

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

    /* SM_REQUIRE(ud == NULL || strlen(ud) >= 23); */
    t = curtime();
    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[20];        /* 1979 */
    *q++ = *p++;
    *q++ = *p++;
    *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
    {
        tz = NULL;
#if TZ_TYPE == TZ_TM_NAME
        tz = lt->tm_name;
#endif /* TZ_TYPE == TZ_TM_NAME */
#if TZ_TYPE == TZ_TM_ZONE
        tz = lt->tm_zone;
#endif /* TZ_TYPE == TZ_TM_ZONE */
#if TZ_TYPE == TZ_TZNAME
        {
            extern char *tzname[];

            if (lt->tm_isdst > 0)
                tz = tzname[1];
            else if (lt->tm_isdst == 0)
                tz = tzname[0];
            else
                tz = NULL;
        }
#endif /* TZ_TYPE == TZ_TZNAME */
#if TZ_TYPE == TZ_TIMEZONE
        {
            extern char *timezone();

            tz = timezone(off, lt->tm_isdst);
        }
#endif /* TZ_TYPE == TZ_TIMEZONE */
        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';
        if (tz != NULL && *tz != '\0')
        {
            *q++ = ' ';
            *q++ = '(';
            while (*tz != '\0' && q < &b[sizeof b - 3])
                *q++ = *tz++;
            *q++ = ')';
        }
    }
    *q = '\0';

    return b;
}