/* $Id: atot.c,v 1.1 2003/03/29 06:19:07 wafer Exp $ */

/* Convert a string to a time value; this is mostly grafted from the
 * BSD 'date' source, so: */

/*
 * Copyright (c) 1985, 1987, 1988, 1993
 *	The 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.
 */

#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#ifndef	TM_YEAR_BASE
#define	TM_YEAR_BASE	1900
#endif

#define	ATOI2(s)	((s) += 2, ((s)[-2] - '0') * 10 + ((s)[-1] - '0'))

void badformat ()
{
     fprintf(stderr, "Bad time format\n");
     exit(1);
}
     
char isdigit (char c)
{
     return c >= '0' && c <= '9';
}

void atot (time_t *tval, const char *p)
{
     struct tm *lt = malloc(sizeof(struct tm));
     const char *dot, *t;
     int century;

     for (t = p, dot = NULL; *t; ++t) {
	  if (isdigit(*t) || *t == ':')
	       continue;
	  if (*t == '.' && dot == NULL) {
	       dot = t;
	       continue;
	  }
	  badformat();
     }

     time(tval);
     localtime_r(tval, lt);
     
     if (dot != NULL) {			/* .ss */
	  dot++; 
	  if (strlen(dot) != 2)
	       badformat();
	  lt->tm_sec = ATOI2(dot);
	  if (lt->tm_sec > 61)
	       badformat();
     } else
	  lt->tm_sec = 0;

     century = 0;
     /* if p has a ".ss" field then let's pretend it's not there */
     switch (strlen(p) - ((dot != NULL) ? 3 : 0)) {
     case 13:				/* cc */
	  lt->tm_year = ATOI2(p) * 100 - TM_YEAR_BASE;
	  century = 1;
	  /* FALLTHROUGH */
     case 11:				/* yy */
	  if (century)
	       lt->tm_year += ATOI2(p);
	  else {
	       lt->tm_year = ATOI2(p) + 2000 - TM_YEAR_BASE;
	  }
	  /* FALLTHROUGH */
     case 9:					/* mm */
	  lt->tm_mon = ATOI2(p);
	  if (lt->tm_mon > 12)
	       badformat();
	  --lt->tm_mon;		/* time struct is 0 - 11 */
	  /* FALLTHROUGH */
     case 7:					/* dd */
	  lt->tm_mday = ATOI2(p);
	  if (lt->tm_mday > 31)
	       badformat();
	  /* FALLTHROUGH */
     case 5:					/* HH */
	  lt->tm_hour = ATOI2(p);
	  if (lt->tm_hour > 23)
	       badformat();
	  p++; /* jump over the colon */
	  /* FALLTHROUGH */
     case 2:					/* MM */
	  lt->tm_min = ATOI2(p);
	  if (lt->tm_min > 59)
	       badformat();
	  break;
     default:
	  badformat();
     }

     /* Let mktime() decide whether summer time is in effect. */
     lt->tm_isdst = -1;

     /* convert broken-down time to GMT clock time */
     if ((*tval = mktime(lt)) == -1)
	  badformat();

     free(lt);
     return;
}