usr/src/lib/libc/port/gen/ctime.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 /*
  33  * This routine converts time as follows.
  34  * The epoch is 0000 Jan 1 1970 GMT.
  35  * The argument time is in seconds since then.
  36  * The localtime(t) entry returns a pointer to an array
  37  * containing
  38  *  seconds (0-59)
  39  *  minutes (0-59)
  40  *  hours (0-23)
  41  *  day of month (1-31)
  42  *  month (0-11)
  43  *  year-1970
  44  *  weekday (0-6, Sun is 0)
  45  *  day of the year
  46  *  daylight savings flag
  47  *
  48  * The routine corrects for daylight saving
  49  * time and will work in any time zone provided
  50  * "timezone" is adjusted to the difference between
  51  * Greenwich and local standard time (measured in seconds).
  52  * In places like Michigan "daylight" must
  53  * be initialized to 0 to prevent the conversion
  54  * to daylight time.
  55  * There is a table which accounts for the peculiarities
  56  * undergone by daylight time in 1974-1975.
  57  *
  58  * The routine does not work
  59  * in Saudi Arabia which runs on Solar time.
  60  *
  61  * asctime(tvec)
  62  * where tvec is produced by localtime
  63  * returns a ptr to a character string
  64  * that has the ascii time in the form
  65  *      Thu Jan 01 00:00:00 1970\n\0
  66  *      01234567890123456789012345
  67  *      0         1         2
  68  *
  69  * ctime(t) just calls localtime, then asctime.
  70  *
  71  * tzset() looks for an environment variable named
  72  * TZ.
  73  * If the variable is present, it will set the external
  74  * variables "timezone", "altzone", "daylight", and "tzname"
  75  * appropriately. It is called by localtime, and
  76  * may also be called explicitly by the user.
  77  */
  78
  79 #include "lint.h"
  80 #include <mtlib.h>
  81 #include <sys/types.h>
  82 #include <time.h>
  83 #include <errno.h>
  84 #include <thread.h>
  85 #include <synch.h>
  86 #include "libc.h"
  87 #include "tsd.h"
  88
  89 #define dysize(A) (((A)%4)? 365: 366)
  90 #define CBUFSIZ 26
  91
  92 static char *
  93 ct_numb(char *cp, int n, char pad)
  94 {
  95         cp++;
  96         if (n >= 10)
  97                 *cp++ = (n / 10) % 10 + '0';
  98         else
  99                 *cp++ = pad;
 100         *cp++ = n % 10 + '0';
 101         return (cp);
 102 }
 103
 104 /*
 105  * POSIX.1c standard version of the function asctime_r.
 106  * User gets it via static asctime_r from the header file.
 107  */
 108 char *
 109 __posix_asctime_r(const struct tm *t, char *cbuf)
 110 {
 111         char *cp;
 112         const char *ncp;
 113         const char *Date = "Day Mon 00 00:00:00 YYYY\n";
 114         const char *Day  = "SunMonTueWedThuFriSat";
 115         const char *Month = "JanFebMarAprMayJunJulAugSepOctNovDec";
 116
 117         int year = t->tm_year + 1900;
 118
 119         cp = cbuf;
 120         for (ncp = Date; *cp++ = *ncp++; /* */)
 121                 ;
 122         ncp = Day + (3 * t->tm_wday);
 123         cp = cbuf;
 124         *cp++ = *ncp++;
 125         *cp++ = *ncp++;
 126         *cp++ = *ncp++;
 127         cp++;
 128         ncp = Month + (3 * t->tm_mon);
 129         *cp++ = *ncp++;
 130         *cp++ = *ncp++;
 131         *cp++ = *ncp++;
 132         cp = ct_numb(cp, t->tm_mday, ' ');
 133         cp = ct_numb(cp, t->tm_hour, '0');
 134         cp = ct_numb(cp, t->tm_min, '0');
 135         cp = ct_numb(cp, t->tm_sec, '0');
 136
 137         if (year < 0 || year >= 10000) {
 138                 /* Only positive, 4-digit years are supported */
 139                 errno = EOVERFLOW;
 140                 return (NULL);
 141         }
 142         cp = ct_numb(cp, year / 100, '0');
 143         cp--;
 144         (void) ct_numb(cp, year, '0');
 145         return (cbuf);
 146 }
 147
 148 /*
 149  * POSIX.1c Draft-6 version of the function asctime_r.
 150  * It was implemented by Solaris 2.3.
 151  */
 152 char *
 153 asctime_r(const struct tm *t, char *cbuf, int buflen)
 154 {
 155         if (buflen < CBUFSIZ) {
 156                 errno = ERANGE;
 157                 return (NULL);
 158         }
 159         return (__posix_asctime_r(t, cbuf));
 160 }
 161
 162 char *
 163 ctime(const time_t *t)
 164 {
 165         char *cbuf = tsdalloc(_T_CTIME, CBUFSIZ, NULL);
 166         struct tm *p;
 167
 168         if (cbuf == NULL)
 169                 return (NULL);
 170         p = localtime(t);
 171         if (p == NULL)
 172                 return (NULL);
 173         return (__posix_asctime_r(p, cbuf));
 174 }
 175
 176 char *
 177 asctime(const struct tm *t)
 178 {
 179         char *cbuf = tsdalloc(_T_CTIME, CBUFSIZ, NULL);
 180
 181         if (cbuf == NULL)
 182                 return (NULL);
 183         return (__posix_asctime_r(t, cbuf));
 184 }