lib/libc/time/getdate.c

   1 /*      $NetBSD: getdate.c,v 1.2 2009/11/22 18:07:39 mbalmer Exp $      */
   2 /*
   3  * Copyright (c) 2009 The NetBSD Foundation, Inc.
   4  * All rights reserved.
   5  *
   6  * This code is derived from software contributed to The NetBSD Foundation
   7  * by Brian Ginsbach.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  20  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  21  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  22  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  28  * POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #include <sys/stat.h>
  32
  33 #include <errno.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <time.h>
  38 #include <unistd.h>
  39 #include <util.h>
  40
  41 #define TMSENTINEL      (-1)
  42
  43 /*
  44  * getdate_err is set to one of the following values on error.
  45  *
  46  * 1    The DATEMSK environment variable is null or undefined.
  47  * 2    The template file cannot be opened for reading.
  48  * 3    Failed to get file status information.
  49  * 4    Template file is not a regular file.
  50  * 5    Encountered an error while reading the template file.
  51  * 6    Cannot allocate memory.
  52  * 7    Input string does not match any line in the template.
  53  * 8    Input string is invalid (for example, February 31) or could not
  54  *      be represented in a time_t.
  55  */
  56
  57 int getdate_err;
  58
  59 struct tm *
  60 getdate(const char *str)
  61 {
  62         char *datemsk, *line, *rp;
  63         FILE *fp;
  64         struct stat sb;
  65         static struct tm rtm, tmnow;
  66         struct tm *tmp, *rtmp = &rtm;
  67         size_t lineno = 0;
  68         time_t now;
  69
  70         if (((datemsk = getenv("DATEMSK")) == NULL) || *datemsk == '\0') {
  71                 getdate_err = 1;
  72                 return (NULL);
  73         }
  74
  75         if (stat(datemsk, &sb) < 0) {
  76                 getdate_err = 3;
  77                 return (NULL);
  78         }
  79
  80         if ((sb.st_mode & S_IFMT) != S_IFREG) {
  81                 getdate_err = 4;
  82                 return (NULL);
  83         }
  84
  85         if ((fp = fopen(datemsk, "r")) == NULL) {
  86                 getdate_err = 2;
  87                 return (NULL);
  88         }
  89
  90         /* loop through datemsk file */
  91         errno = 0;
  92         rp = NULL;
  93         while ((line = fparseln(fp, NULL, &lineno, NULL, 0)) != NULL) {
  94                 /* initialize tmp with sentinels */
  95                 rtm.tm_sec = rtm.tm_min = rtm.tm_hour = TMSENTINEL;
  96                 rtm.tm_mday = rtm.tm_mon = rtm.tm_year = TMSENTINEL;
  97                 rtm.tm_wday = rtm.tm_yday = rtm.tm_isdst = TMSENTINEL;
  98                 rtm.tm_gmtoff = 0;
  99                 rtm.tm_zone = NULL;
 100                 rp = strptime(str, line, rtmp);
 101                 free(line);
 102                 if (rp != NULL)
 103                         break;
 104                 errno = 0;
 105         }
 106         if (errno != 0 || ferror(fp)) {
 107                 if (errno == ENOMEM)
 108                         getdate_err = 6;
 109                 else
 110                         getdate_err = 5;
 111                 fclose(fp);
 112                 return (NULL);
 113         }
 114         if (feof(fp) || (rp != NULL && *rp != '\0')) {
 115                 getdate_err = 7;
 116                 return (NULL);
 117         }
 118         fclose(fp);
 119
 120         time(&now);
 121         tmp = localtime(&now);
 122         tmnow = *tmp;
 123
 124         /*
 125          * This implementation does not accept setting the broken-down time
 126          * to anything other than the localtime().  It is not possible to
 127          * change the scanned timezone with %Z.
 128          *
 129          * Note IRIX and Solaris accept only the current zone for %Z.
 130          * XXX Is there any implementation that matches the standard?
 131          * XXX (Or am I reading the standard wrong?)
 132          *
 133          * Note: Neither XPG 6 (POSIX 2004) nor XPG 7 (POSIX 2008)
 134          * requires strptime(3) support for %Z.
 135          */
 136
 137         /*
 138          * Given only a weekday find the first matching weekday starting
 139          * with the current weekday and moving into the future.
 140          */
 141         if (rtm.tm_wday != TMSENTINEL && rtm.tm_year == TMSENTINEL &&
 142             rtm.tm_mon == TMSENTINEL && rtm.tm_mday == TMSENTINEL) {
 143                 rtm.tm_year = tmnow.tm_year;
 144                 rtm.tm_mon = tmnow.tm_mon;
 145                 rtm.tm_mday = tmnow.tm_mday +
 146                         (rtm.tm_wday - tmnow.tm_wday + 7) % 7;
 147         }
 148
 149         /*
 150          * Given only a month (and no year) find the first matching month
 151          * starting with the current month and moving into the future.
 152          */
 153         if (rtm.tm_mon != TMSENTINEL) {
 154                 if (rtm.tm_year == TMSENTINEL) {
 155                         rtm.tm_year = tmnow.tm_year +
 156                                 ((rtm.tm_mon < tmnow.tm_mon)? 1 : 0);
 157                 }
 158                 if (rtm.tm_mday == TMSENTINEL) {
 159                         /* assume the first of the month */
 160                         rtm.tm_mday = 1;
 161                         /*
 162                          * XXX This isn't documented! Just observed behavior.
 163                          *
 164                          * Given the weekday find the first matching weekday
 165                          * starting with the weekday of the first day of the
 166                          * the month and moving into the future.
 167                          */
 168                         if (rtm.tm_wday != TMSENTINEL) {
 169                                 struct tm tm;
 170
 171                                 memset(&tm, 0, sizeof(struct tm));
 172                                 tm.tm_year = rtm.tm_year;
 173                                 tm.tm_mon = rtm.tm_mon;
 174                                 tm.tm_mday = 1;
 175                                 mktime(&tm);
 176                                 rtm.tm_mday +=
 177                                         (rtm.tm_wday - tm.tm_wday + 7) % 7;
 178                         }
 179                 }
 180         }
 181
 182         /*
 183          * Given no time of day assume the current time of day.
 184          */
 185         if (rtm.tm_hour == TMSENTINEL &&
 186             rtm.tm_min == TMSENTINEL && rtm.tm_sec == TMSENTINEL) {
 187                 rtm.tm_hour = tmnow.tm_hour;
 188                 rtm.tm_min = tmnow.tm_min;
 189                 rtm.tm_sec = tmnow.tm_sec;
 190         }
 191         /*
 192          * Given an hour and no date, find the first matching hour starting
 193          * with the current hour and moving into the future
 194          */
 195         if (rtm.tm_hour != TMSENTINEL &&
 196             rtm.tm_year == TMSENTINEL && rtm.tm_mon == TMSENTINEL &&
 197             rtm.tm_mday == TMSENTINEL) {
 198                 rtm.tm_year = tmnow.tm_year;
 199                 rtm.tm_mon = tmnow.tm_mon;
 200                 rtm.tm_mday = tmnow.tm_mday;
 201                 if (rtm.tm_hour < tmnow.tm_hour)
 202                         rtm.tm_hour += 24;
 203         }
 204
 205         /*
 206          * Set to 'sane' values; mktime(3) does funny things otherwise.
 207          * No hours, no minutes, no seconds, no service.
 208          */
 209         if (rtm.tm_hour == TMSENTINEL)
 210                 rtm.tm_hour = 0;
 211         if (rtm.tm_min == TMSENTINEL)
 212                 rtm.tm_min = 0;
 213         if (rtm.tm_sec == TMSENTINEL)
 214                 rtm.tm_sec = 0;
 215
 216         /*
 217          * Given only a year the values of month, day of month, day of year,
 218          * week day and is daylight (summer) time are unspecified.
 219          * (Specified on the Solaris man page not POSIX.)
 220          */
 221         if (rtm.tm_year != TMSENTINEL &&
 222             rtm.tm_mon == TMSENTINEL && rtm.tm_mday == TMSENTINEL) {
 223                 rtm.tm_mon = 0;
 224                 rtm.tm_mday = 1;
 225                 /*
 226                  * XXX More undocumented functionality but observed.
 227                  *
 228                  * Given the weekday find the first matching weekday
 229                  * starting with the weekday of the first day of the
 230                  * month and moving into the future.
 231                  */
 232                 if (rtm.tm_wday != TMSENTINEL) {
 233                         struct tm tm;
 234
 235                         memset(&tm, 0, sizeof(struct tm));
 236                         tm.tm_year = rtm.tm_year;
 237                         tm.tm_mon = rtm.tm_mon;
 238                         tm.tm_mday = 1;
 239                         mktime(&tm);
 240                         rtm.tm_mday += (rtm.tm_wday - tm.tm_wday + 7) % 7;
 241                 }
 242         }
 243
 244         /*
 245          * Given only the century but no year within, the current year
 246          * is assumed.  (Specified on the Solaris man page not POSIX.)
 247          *
 248          * Warning ugly end case
 249          *
 250          * This is more work since strptime(3) doesn't "do the right thing".
 251          */
 252         if (rtm.tm_year != TMSENTINEL && (rtm.tm_year - 1900) >= 0) {
 253                 rtm.tm_year -= 1900;
 254                 rtm.tm_year += (tmnow.tm_year % 100);
 255         }
 256
 257         /*
 258          * mktime() will normalize all values and also check that the
 259          * value will fit into a time_t.
 260          *
 261          * This is only for POSIX correctness.  A date >= 1900 is
 262          * really ok, but using a time_t limits things.
 263          */
 264         if (mktime(rtmp) < 0) {
 265                 getdate_err = 8;
 266                 return (NULL);
 267         }
 268
 269         return (rtmp);
 270 }