time/getdate.c

   1 /* Convert a string representation of time to a time value.
   2    Copyright (C) 1997, 1998, 1999, 2000 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 #define TM_YEAR_BASE 1900
  29
  30
  31 /* Prototypes for local functions.  */
  32 static int first_wday (int year, int mon, int wday);
  33 static int check_mday (int year, int mon, int mday);
  34
  35
  36 /* Set to one of the following values to indicate an error.
  37      1  the DATEMSK environment variable is null or undefined,
  38      2  the template file cannot be opened for reading,
  39      3  failed to get file status information,
  40      4  the template file is not a regular file,
  41      5  an error is encountered while reading the template file,
  42      6  memory allication failed (not enough memory available),
  43      7  there is no line in the template that matches the input,
  44      8  invalid input specification Example: February 31 or a time is
  45         specified that can not be represented in a time_t (representing
  46         the time in seconds since 00:00:00 UTC, January 1, 1970) */
  47 int getdate_err;
  48
  49
  50 /* Returns the first weekday WDAY of month MON in the year YEAR.  */
  51 static int
  52 first_wday (int year, int mon, int wday)
  53 {
  54   struct tm tm;
  55
  56   if (wday == INT_MIN)
  57     return 1;
  58
  59   memset (&tm, 0, sizeof (struct tm));
  60   tm.tm_year = year;
  61   tm.tm_mon = mon;
  62   tm.tm_mday = 1;
  63   mktime (&tm);
  64
  65   return (1 + (wday - tm.tm_wday + 7) % 7);
  66 }
  67
  68
  69 /* Returns 1 if MDAY is a valid day of the month in month MON of year
  70    YEAR, and 0 if it is not.  */
  71 static int
  72 check_mday (int year, int mon, int mday)
  73 {
  74   switch (mon)
  75     {
  76     case 0:
  77     case 2:
  78     case 4:
  79     case 6:
  80     case 7:
  81     case 9:
  82     case 11:
  83       if (mday >= 1 && mday <= 31)
  84         return 1;
  85       break;
  86     case 3:
  87     case 5:
  88     case 8:
  89     case 10:
  90       if (mday >= 1 && mday <= 30)
  91         return 1;
  92       break;
  93     case 1:
  94       if (mday >= 1 && mday <= (__isleap (year) ? 29 : 28))
  95         return 1;
  96       break;
  97     }
  98
  99   return 0;
 100 }
 101
 102
 103 int
 104 __getdate_r (const char *string, struct tm *tp)
 105 {
 106   FILE *fp;
 107   char *line;
 108   size_t len;
 109   char *datemsk;
 110   char *result = NULL;
 111   time_t timer;
 112   struct tm tm;
 113   struct stat st;
 114   int mday_ok = 0;
 115
 116   datemsk = getenv ("DATEMSK");
 117   if (datemsk == NULL || *datemsk == '\0')
 118     return 1;
 119
 120   if (stat (datemsk, &st) < 0)
 121     return 3;
 122
 123   if (!S_ISREG (st.st_mode))
 124     return 4;
 125
 126   /* Open the template file.  */
 127   fp = fopen (datemsk, "r");
 128   if (fp == NULL)
 129     return 2;
 130
 131   line = NULL;
 132   len = 0;
 133   do
 134     {
 135       ssize_t n;
 136
 137       n = __getline (&line, &len, fp);
 138       if (n < 0)
 139         break;
 140       if (line[n - 1] == '\n')
 141         line[n - 1] = '\0';
 142
 143       /* Do the conversion.  */
 144       tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
 145       tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
 146       result = strptime (string, line, tp);
 147       if (result && *result == '\0')
 148         break;
 149     }
 150   while (!feof_unlocked (fp));
 151
 152   /* Free the buffer.  */
 153   free (line);
 154
 155   /* Check for errors. */
 156   if (ferror_unlocked (fp))
 157     {
 158       fclose (fp);
 159       return 5;
 160     }
 161
 162   /* Close template file.  */
 163   fclose (fp);
 164
 165   if (result == NULL || *result != '\0')
 166     return 7;
 167
 168   /* Get current time.  */
 169   time (&timer);
 170   __localtime_r (&timer, &tm);
 171
 172   /* If only the weekday is given, today is assumed if the given day
 173      is equal to the current day and next week if it is less.  */
 174   if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
 175       && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
 176     {
 177       tp->tm_year = tm.tm_year;
 178       tp->tm_mon = tm.tm_mon;
 179       tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
 180       mday_ok = 1;
 181     }
 182
 183   /* If only the month is given, the current month is assumed if the
 184      given month is equal to the current month and next year if it is
 185      less and no year is given (the first day of month is assumed if
 186      no day is given.  */
 187   if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
 188     {
 189       if (tp->tm_year == INT_MIN)
 190         tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
 191       tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
 192       mday_ok = 1;
 193     }
 194
 195   /* If no hour, minute and second are given the current hour, minute
 196      and second are assumed.  */
 197   if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
 198     {
 199       tp->tm_hour = tm.tm_hour;
 200       tp->tm_min = tm.tm_min;
 201       tp->tm_sec = tm.tm_sec;
 202     }
 203
 204   /* If no date is given, today is assumed if the given hour is
 205      greater than the current hour and tomorrow is assumed if
 206      it is less.  */
 207   if (tp->tm_hour >= 0 && tp->tm_hour <= 23
 208       && tp->tm_year == INT_MIN && tp->tm_mon == INT_MIN
 209       && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
 210     {
 211       tp->tm_year = tm.tm_year;
 212       tp->tm_mon = tm.tm_mon;
 213       tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
 214       mday_ok = 1;
 215     }
 216
 217   /* Fill in the gaps.  */
 218   if (tp->tm_year == INT_MIN)
 219     tp->tm_year = tm.tm_year;
 220   if (tp->tm_hour == INT_MIN)
 221     tp->tm_hour = 0;
 222   if (tp->tm_min == INT_MIN)
 223     tp->tm_min = 0;
 224   if (tp->tm_sec == INT_MIN)
 225     tp->tm_sec = 0;
 226
 227   /* Check if the day of month is within range, and if the time can be
 228      represented in a time_t.  We make use of the fact that the mktime
 229      call normalizes the struct tm.  */
 230   if ((!mday_ok && !check_mday (TM_YEAR_BASE + tp->tm_year, tp->tm_mon,
 231                                 tp->tm_mday))
 232       || mktime (tp) == (time_t) -1)
 233     return 8;
 234
 235   return 0;
 236 }
 237 #ifdef weak_alias
 238 weak_alias (__getdate_r, getdate_r)
 239 #endif
 240
 241
 242 struct tm *
 243 getdate (const char *string)
 244 {
 245   /* Buffer returned by getdate.  */
 246   static struct tm tmbuf;
 247   int errval = __getdate_r (string, &tmbuf);
 248
 249   if (errval != 0)
 250     {
 251       getdate_err = errval;
 252       return NULL;
 253     }
 254
 255   return &tmbuf;
 256 }