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unctime.c revision 1.1.1.2
      1 /*-
      2  * Copyright (c) 1980, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #ifndef lint
     35 static char sccsid[] = "@(#)unctime.c	8.1 (Berkeley) 6/5/93";
     36 #endif /* not lint */
     37 
     38 #include <sys/types.h>
     39 
     40 #include <stdio.h>
     41 #include <time.h>
     42 #ifdef __STDC__
     43 #include <stdlib.h>
     44 #include <string.h>
     45 #endif
     46 
     47 #ifndef __P
     48 #include <sys/cdefs.h>
     49 #endif
     50 
     51 /*
     52  * Convert a ctime(3) format string into a system format date.
     53  * Return the date thus calculated.
     54  *
     55  * Return -1 if the string is not in ctime format.
     56  */
     57 
     58 /*
     59  * Offsets into the ctime string to various parts.
     60  */
     61 
     62 #define	E_MONTH		4
     63 #define	E_DAY		8
     64 #define	E_HOUR		11
     65 #define	E_MINUTE	14
     66 #define	E_SECOND	17
     67 #define	E_YEAR		20
     68 
     69 static	int dcmp __P((struct tm *, struct tm *));
     70 static	time_t emitl __P((struct tm *));
     71 static	int lookup __P((char *));
     72 
     73 
     74 time_t
     75 unctime(str)
     76 	char *str;
     77 {
     78 	struct tm then;
     79 	char dbuf[26];
     80 
     81 	(void) strncpy(dbuf, str, sizeof(dbuf) - 1);
     82 	dbuf[sizeof(dbuf) - 1] = '\0';
     83 	dbuf[E_MONTH+3] = '\0';
     84 	if ((then.tm_mon = lookup(&dbuf[E_MONTH])) < 0)
     85 		return (-1);
     86 	then.tm_mday = atoi(&dbuf[E_DAY]);
     87 	then.tm_hour = atoi(&dbuf[E_HOUR]);
     88 	then.tm_min = atoi(&dbuf[E_MINUTE]);
     89 	then.tm_sec = atoi(&dbuf[E_SECOND]);
     90 	then.tm_year = atoi(&dbuf[E_YEAR]) - 1900;
     91 	return(emitl(&then));
     92 }
     93 
     94 static char months[] =
     95 	"JanFebMarAprMayJunJulAugSepOctNovDec";
     96 
     97 static int
     98 lookup(str)
     99 	char *str;
    100 {
    101 	register char *cp, *cp2;
    102 
    103 	for (cp = months, cp2 = str; *cp != '\0'; cp += 3)
    104 		if (strncmp(cp, cp2, 3) == 0)
    105 			return((cp-months) / 3);
    106 	return(-1);
    107 }
    108 /*
    109  * Routine to convert a localtime(3) format date back into
    110  * a system format date.
    111  *
    112  *	Use a binary search.
    113  */
    114 
    115 static time_t
    116 emitl(dp)
    117 	struct tm *dp;
    118 {
    119 	time_t conv;
    120 	register int i, bit;
    121 	struct tm dcopy;
    122 
    123 	dcopy = *dp;
    124 	dp = &dcopy;
    125 	conv = 0;
    126 	for (i = 30; i >= 0; i--) {
    127 		bit = 1 << i;
    128 		conv |= bit;
    129 		if (dcmp(localtime(&conv), dp) > 0)
    130 			conv &= ~bit;
    131 	}
    132 	return(conv);
    133 }
    134 
    135 /*
    136  * Compare two localtime dates, return result.
    137  */
    138 
    139 #define DECIDE(a) \
    140 	if (dp->a > dp2->a) \
    141 		return(1); \
    142 	if (dp->a < dp2->a) \
    143 		return(-1)
    144 
    145 static int
    146 dcmp(dp, dp2)
    147 	register struct tm *dp, *dp2;
    148 {
    149 
    150 	DECIDE(tm_year);
    151 	DECIDE(tm_mon);
    152 	DECIDE(tm_mday);
    153 	DECIDE(tm_hour);
    154 	DECIDE(tm_min);
    155 	DECIDE(tm_sec);
    156 	return(0);
    157 }
    158