time/getdate.c

   1 /* Convert a string representation of time to a time value.
   2    Copyright (C) 1997-2001,2003,2011 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 Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <limits.h>
  21 #include <stdio.h>
  22 #include <stdio_ext.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <time.h>
  26 #include <unistd.h>
  27 #include <sys/stat.h>
  28
  29 #define TM_YEAR_BASE 1900
  30
  31
  32 /* Prototypes for local functions.  */
  33 static int first_wday (int year, int mon, int wday);
  34 static int check_mday (int year, int mon, int mday);
  35
  36
  37 /* Set to one of the following values to indicate an error.
  38      1  the DATEMSK environment variable is null or undefined,
  39      2  the template file cannot be opened for reading,
  40      3  failed to get file status information,
  41      4  the template file is not a regular file,
  42      5  an error is encountered while reading the template file,
  43      6  memory allication failed (not enough memory available),
  44      7  there is no line in the template that matches the input,
  45      8  invalid input specification Example: February 31 or a time is
  46         specified that can not be represented in a time_t (representing
  47         the time in seconds since 00:00:00 UTC, January 1, 1970) */
  48 int getdate_err;
  49
  50
  51 /* Returns the first weekday WDAY of month MON in the year YEAR.  */
  52 static int
  53 first_wday (int year, int mon, int wday)
  54 {
  55   struct tm tm;
  56
  57   if (wday == INT_MIN)
  58     return 1;
  59
  60   memset (&tm, 0, sizeof (struct tm));
  61   tm.tm_year = year;
  62   tm.tm_mon = mon;
  63   tm.tm_mday = 1;
  64   mktime (&tm);
  65
  66   return (1 + (wday - tm.tm_wday + 7) % 7);
  67 }
  68
  69
  70 /* Returns 1 if MDAY is a valid day of the month in month MON of year
  71    YEAR, and 0 if it is not.  */
  72 static int
  73 check_mday (int year, int mon, int mday)
  74 {
  75   switch (mon)
  76     {
  77     case 0:
  78     case 2:
  79     case 4:
  80     case 6:
  81     case 7:
  82     case 9:
  83     case 11:
  84       if (mday >= 1 && mday <= 31)
  85         return 1;
  86       break;
  87     case 3:
  88     case 5:
  89     case 8:
  90     case 10:
  91       if (mday >= 1 && mday <= 30)
  92         return 1;
  93       break;
  94     case 1:
  95       if (mday >= 1 && mday <= (__isleap (year) ? 29 : 28))
  96         return 1;
  97       break;
  98     }
  99
 100   return 0;
 101 }
 102
 103
 104 int
 105 __getdate_r (const char *string, struct tm *tp)
 106 {
 107   FILE *fp;
 108   char *line;
 109   size_t len;
 110   char *datemsk;
 111   char *result = NULL;
 112   time_t timer;
 113   struct tm tm;
 114   struct stat64 st;
 115   int mday_ok = 0;
 116
 117   datemsk = getenv ("DATEMSK");
 118   if (datemsk == NULL || *datemsk == '\0')
 119     return 1;
 120
 121   if (stat64 (datemsk, &st) < 0)
 122     return 3;
 123
 124   if (!S_ISREG (st.st_mode))
 125     return 4;
 126
 127   if (__access (datemsk, R_OK) < 0)
 128     return 2;
 129
 130   /* Open the template file.  */
 131   fp = fopen (datemsk, "rce");
 132   if (fp == NULL)
 133     return 2;
 134
 135   /* No threads reading this stream.  */
 136   __fsetlocking (fp, FSETLOCKING_BYCALLER);
 137
 138   line = NULL;
 139   len = 0;
 140   do
 141     {
 142       ssize_t n;
 143
 144       n = __getline (&line, &len, fp);
 145       if (n < 0)
 146         break;
 147       if (line[n - 1] == '\n')
 148         line[n - 1] = '\0';
 149
 150       /* Do the conversion.  */
 151       tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
 152       tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
 153       tp->tm_isdst = -1;
 154       tp->tm_gmtoff = 0;
 155       tp->tm_zone = NULL;
 156       result = strptime (string, line, tp);
 157       if (result && *result == '\0')
 158         break;
 159     }
 160   while (!feof_unlocked (fp));
 161
 162   /* Free the buffer.  */
 163   free (line);
 164
 165   /* Check for errors. */
 166   if (ferror_unlocked (fp))
 167     {
 168       fclose (fp);
 169       return 5;
 170     }
 171
 172   /* Close template file.  */
 173   fclose (fp);
 174
 175   if (result == NULL || *result != '\0')
 176     return 7;
 177
 178   /* Get current time.  */
 179   time (&timer);
 180   __localtime_r (&timer, &tm);
 181
 182   /* If only the weekday is given, today is assumed if the given day
 183      is equal to the current day and next week if it is less.  */
 184   if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
 185       && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
 186     {
 187       tp->tm_year = tm.tm_year;
 188       tp->tm_mon = tm.tm_mon;
 189       tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
 190       mday_ok = 1;
 191     }
 192
 193   /* If only the month is given, the current month is assumed if the
 194      given month is equal to the current month and next year if it is
 195      less and no year is given (the first day of month is assumed if
 196      no day is given.  */
 197   if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
 198     {
 199       if (tp->tm_year == INT_MIN)
 200         tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
 201       tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
 202       mday_ok = 1;
 203     }
 204
 205   /* If no hour, minute and second are given the current hour, minute
 206      and second are assumed.  */
 207   if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
 208     {
 209       tp->tm_hour = tm.tm_hour;
 210       tp->tm_min = tm.tm_min;
 211       tp->tm_sec = tm.tm_sec;
 212     }
 213
 214   /* Fill in the gaps.  */
 215   if (tp->tm_hour == INT_MIN)
 216     tp->tm_hour = 0;
 217   if (tp->tm_min == INT_MIN)
 218     tp->tm_min = 0;
 219   if (tp->tm_sec == INT_MIN)
 220     tp->tm_sec = 0;
 221
 222   /* If no date is given, today is assumed if the given hour is
 223      greater than the current hour and tomorrow is assumed if
 224      it is less.  */
 225   if (tp->tm_hour >= 0 && tp->tm_hour <= 23
 226       && tp->tm_mon == INT_MIN
 227       && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
 228     {
 229       tp->tm_mon = tm.tm_mon;
 230       tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
 231       mday_ok = 1;
 232     }
 233
 234   /* More fillers.  */
 235   if (tp->tm_year == INT_MIN)
 236     tp->tm_year = tm.tm_year;
 237   if (tp->tm_mon == INT_MIN)
 238     tp->tm_mon = tm.tm_mon;
 239
 240   /* Check if the day of month is within range, and if the time can be
 241      represented in a time_t.  We make use of the fact that the mktime
 242      call normalizes the struct tm.  */
 243   if ((!mday_ok && !check_mday (TM_YEAR_BASE + tp->tm_year, tp->tm_mon,
 244                                 tp->tm_mday))
 245       || mktime (tp) == (time_t) -1)
 246     return 8;
 247
 248   return 0;
 249 }
 250 #ifdef weak_alias
 251 weak_alias (__getdate_r, getdate_r)
 252 #endif
 253
 254
 255 struct tm *
 256 getdate (const char *string)
 257 {
 258   /* Buffer returned by getdate.  */
 259   static struct tm tmbuf;
 260   int errval = __getdate_r (string, &tmbuf);
 261
 262   if (errval != 0)
 263     {
 264       getdate_err = errval;
 265       return NULL;
 266     }
 267
 268   return &tmbuf;
 269 }