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 <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, "r");
 132   if (fp == NULL)
 133     return 2;
 134
 135   line = NULL;
 136   len = 0;
 137   do
 138     {
 139       ssize_t n;
 140
 141       n = __getline (&line, &len, fp);
 142       if (n < 0)
 143         break;
 144       if (line[n - 1] == '\n')
 145         line[n - 1] = '\0';
 146
 147       /* Do the conversion.  */
 148       tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
 149       tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
 150       result = strptime (string, line, tp);
 151       if (result && *result == '\0')
 152         break;
 153     }
 154   while (!feof_unlocked (fp));
 155
 156   /* Free the buffer.  */
 157   free (line);
 158
 159   /* Check for errors. */
 160   if (ferror_unlocked (fp))
 161     {
 162       fclose (fp);
 163       return 5;
 164     }
 165
 166   /* Close template file.  */
 167   fclose (fp);
 168
 169   if (result == NULL || *result != '\0')
 170     return 7;
 171
 172   /* Get current time.  */
 173   time (&timer);
 174   __localtime_r (&timer, &tm);
 175
 176   /* If only the weekday is given, today is assumed if the given day
 177      is equal to the current day and next week if it is less.  */
 178   if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
 179       && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
 180     {
 181       tp->tm_year = tm.tm_year;
 182       tp->tm_mon = tm.tm_mon;
 183       tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
 184       mday_ok = 1;
 185     }
 186
 187   /* If only the month is given, the current month is assumed if the
 188      given month is equal to the current month and next year if it is
 189      less and no year is given (the first day of month is assumed if
 190      no day is given.  */
 191   if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
 192     {
 193       if (tp->tm_year == INT_MIN)
 194         tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
 195       tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
 196       mday_ok = 1;
 197     }
 198
 199   /* If no hour, minute and second are given the current hour, minute
 200      and second are assumed.  */
 201   if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
 202     {
 203       tp->tm_hour = tm.tm_hour;
 204       tp->tm_min = tm.tm_min;
 205       tp->tm_sec = tm.tm_sec;
 206     }
 207
 208   /* If no date is given, today is assumed if the given hour is
 209      greater than the current hour and tomorrow is assumed if
 210      it is less.  */
 211   if (tp->tm_hour >= 0 && tp->tm_hour <= 23
 212       && tp->tm_year == INT_MIN && tp->tm_mon == INT_MIN
 213       && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
 214     {
 215       tp->tm_year = tm.tm_year;
 216       tp->tm_mon = tm.tm_mon;
 217       tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
 218       mday_ok = 1;
 219     }
 220
 221   /* Fill in the gaps.  */
 222   if (tp->tm_year == INT_MIN)
 223     tp->tm_year = tm.tm_year;
 224   if (tp->tm_hour == INT_MIN)
 225     tp->tm_hour = 0;
 226   if (tp->tm_min == INT_MIN)
 227     tp->tm_min = 0;
 228   if (tp->tm_sec == INT_MIN)
 229     tp->tm_sec = 0;
 230
 231   /* Check if the day of month is within range, and if the time can be
 232      represented in a time_t.  We make use of the fact that the mktime
 233      call normalizes the struct tm.  */
 234   if ((!mday_ok && !check_mday (TM_YEAR_BASE + tp->tm_year, tp->tm_mon,
 235                                 tp->tm_mday))
 236       || mktime (tp) == (time_t) -1)
 237     return 8;
 238
 239   return 0;
 240 }
 241 #ifdef weak_alias
 242 weak_alias (__getdate_r, getdate_r)
 243 #endif
 244
 245
 246 struct tm *
 247 getdate (const char *string)
 248 {
 249   /* Buffer returned by getdate.  */
 250   static struct tm tmbuf;
 251   int errval = __getdate_r (string, &tmbuf);
 252
 253   if (errval != 0)
 254     {
 255       getdate_err = errval;
 256       return NULL;
 257     }
 258
 259   return &tmbuf;
 260 }