time/getdate.c

   1 /* Convert a string representation of time to a time value.
   2    Copyright (C) 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <time.h>
  26 #include <sys/stat.h>
  27
  28
  29 /* Prototypes for local functions.  */
  30 static int first_wday (int year, int mon, int wday);
  31 static int check_mday (int year, int mon, int mday);
  32
  33
  34 /* Set to one of the following values to indicate an error.
  35      1  the DATEMSK environment variable is null or undefined,
  36      2  the template file cannot be opened for reading,
  37      3  failed to get file status information,
  38      4  the template file is not a regular file,
  39      5  an error is encountered while reading the template file,
  40      6  memory allication failed (not enough memory available),
  41      7  there is no line in the template that matches the input,
  42      8  invalid input specification Example: February 31 or a time is
  43         specified that can not be represented in a time_t (representing
  44         the time in seconds since 00:00:00 UTC, January 1, 1970) */
  45 int getdate_err = 0;
  46
  47
  48 /* Returns the first weekday WDAY of month MON in the year YEAR.  */
  49 static int
  50 first_wday (int year, int mon, int wday)
  51 {
  52   struct tm tm;
  53
  54   if (wday == INT_MIN)
  55     return 1;
  56
  57   memset (&tm, 0, sizeof (struct tm));
  58   tm.tm_year = year;
  59   tm.tm_mon = mon;
  60   tm.tm_mday = 1;
  61   mktime (&tm);
  62
  63   return (1 + (wday - tm.tm_wday + 7) % 7);
  64 }
  65
  66
  67 /* Returns 1 if MDAY is a valid day of the month in month MON of year
  68    YEAR, and 0 if it is not.  */
  69 static int
  70 check_mday (int year, int mon, int mday)
  71 {
  72   switch (mon)
  73     {
  74     case 1:
  75     case 3:
  76     case 5:
  77     case 7:
  78     case 8:
  79     case 10:
  80     case 12:
  81       if (mday >= 1 && mday <= 31)
  82         return 1;
  83       break;
  84     case 4:
  85     case 6:
  86     case 9:
  87     case 11:
  88       if (mday >= 1 && mday <= 30)
  89         return 1;
  90       break;
  91     case 2:
  92       if (mday >= 1 && mday < (__isleap (year) ? 29 : 28))
  93         return 1;
  94       break;
  95     }
  96
  97   return 0;
  98 }
  99
 100
 101 int
 102 __getdate_r (const char *string, struct tm *tp)
 103 {
 104   FILE *fp;
 105   char *line;
 106   size_t len;
 107   char *datemsk;
 108   char *result = NULL;
 109   time_t timer;
 110   struct tm tm;
 111   struct stat st;
 112   int mday_ok = 0;
 113
 114   datemsk = getenv ("DATEMSK");
 115   if (datemsk == NULL || *datemsk == '\0')
 116     return 1;
 117
 118   if (stat (datemsk, &st) < 0)
 119     return 3;
 120
 121   if (!S_ISREG (st.st_mode))
 122     return 4;
 123
 124   /* Open the template file.  */
 125   fp = fopen (datemsk, "r");
 126   if (fp == NULL)
 127     return 2;
 128
 129   line = NULL;
 130   len = 0;
 131   do
 132     {
 133       ssize_t n;
 134
 135       n = __getline (&line, &len, fp);
 136       if (n < 0)
 137         break;
 138       if (line[n - 1] == '\n')
 139         line[n - 1] = '\0';
 140
 141       /* Do the conversion.  */
 142       tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
 143       tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
 144       result = strptime (string, line, tp);
 145       if (result && *result == '\0')
 146         break;
 147     }
 148   while (!feof (fp));
 149
 150   /* Free the buffer.  */
 151   free (line);
 152
 153   /* Check for errors. */
 154   if (ferror (fp))
 155     {
 156       fclose (fp);
 157       return 5;
 158     }
 159
 160   /* Close template file.  */
 161   fclose (fp);
 162
 163   if (result == NULL || *result != '\0')
 164     return 7;
 165
 166   /* Get current time.  */
 167   time (&timer);
 168   __localtime_r (&timer, &tm);
 169
 170   /* If only the weekday is given, today is assumed if the given day
 171      is equal to the current day and next week if it is less.  */
 172   if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
 173       && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
 174     {
 175       tp->tm_year = tm.tm_year;
 176       tp->tm_mon = tm.tm_mon;
 177       tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
 178       mday_ok = 1;
 179     }
 180
 181   /* If only the month is given, the current month is assumed if the
 182      given month is equal to the current month and next year if it is
 183      less and no year is given (the first day of month is assumed if
 184      no day is given.  */
 185   if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
 186     {
 187       if (tp->tm_year == INT_MIN)
 188         tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
 189       tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
 190       mday_ok = 1;
 191     }
 192
 193   /* If no hour, minute and second are given the current hour, minute
 194      and second are assumed.  */
 195   if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
 196     {
 197       tp->tm_hour = tm.tm_hour;
 198       tp->tm_min = tm.tm_min;
 199       tp->tm_sec = tm.tm_sec;
 200     }
 201
 202   /* If no date is given, today is assumed if the given hour is
 203      greater than the current hour and tomorrow is assumed if
 204      it is less.  */
 205   if (tp->tm_hour >= 0 && tp->tm_hour <= 23
 206       && tp->tm_year == INT_MIN && tp->tm_mon == INT_MIN
 207       && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
 208     {
 209       tp->tm_year = tm.tm_year;
 210       tp->tm_mon = tm.tm_mon;
 211       tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
 212       mday_ok = 1;
 213     }
 214
 215   /* Fill in the gaps.  */
 216   if (tp->tm_year == INT_MIN)
 217     tp->tm_year = tm.tm_year;
 218   if (tp->tm_hour == INT_MIN)
 219     tp->tm_hour = 0;
 220   if (tp->tm_min == INT_MIN)
 221     tp->tm_min = 0;
 222   if (tp->tm_sec == INT_MIN)
 223     tp->tm_sec = 0;
 224
 225   /* Check if the day of month is within range, and if the time can be
 226      represented in a time_t.  We make use of the fact that the mktime
 227      call normalizes the struct tm.  */
 228   if ((!mday_ok && !check_mday (tp->tm_year, tp->tm_mon, tp->tm_mday))
 229       || mktime (tp) == (time_t) -1)
 230     return 8;
 231
 232   return 0;
 233 }
 234 #ifdef weak_alias
 235 weak_alias (__getdate_r, getdate_r)
 236 #endif
 237
 238
 239 struct tm *
 240 getdate (const char *string)
 241 {
 242   /* Buffer returned by getdate.  */
 243   static struct tm tmbuf;
 244   int errval = __getdate_r (string, &tmbuf);
 245
 246   if (errval != 0)
 247     {
 248       getdate_err = errval;
 249       return NULL;
 250     }
 251
 252   return &tmbuf;
 253 }