time/getdate.c

   1 /* Convert a string representation of time to a time value.
   2    Copyright (C) 1997,1998,1999,2000,2001,2003 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdio_ext.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <time.h>
  27 #include <unistd.h>
  28 #include <sys/stat.h>
  29
  30 #define TM_YEAR_BASE 1900
  31
  32
  33 /* Prototypes for local functions.  */
  34 static int first_wday (int year, int mon, int wday);
  35 static int check_mday (int year, int mon, int mday);
  36
  37
  38 /* Set to one of the following values to indicate an error.
  39      1  the DATEMSK environment variable is null or undefined,
  40      2  the template file cannot be opened for reading,
  41      3  failed to get file status information,
  42      4  the template file is not a regular file,
  43      5  an error is encountered while reading the template file,
  44      6  memory allication failed (not enough memory available),
  45      7  there is no line in the template that matches the input,
  46      8  invalid input specification Example: February 31 or a time is
  47         specified that can not be represented in a time_t (representing
  48         the time in seconds since 00:00:00 UTC, January 1, 1970) */
  49 int getdate_err;
  50
  51
  52 /* Returns the first weekday WDAY of month MON in the year YEAR.  */
  53 static int
  54 first_wday (int year, int mon, int wday)
  55 {
  56   struct tm tm;
  57
  58   if (wday == INT_MIN)
  59     return 1;
  60
  61   memset (&tm, 0, sizeof (struct tm));
  62   tm.tm_year = year;
  63   tm.tm_mon = mon;
  64   tm.tm_mday = 1;
  65   mktime (&tm);
  66
  67   return (1 + (wday - tm.tm_wday + 7) % 7);
  68 }
  69
  70
  71 /* Returns 1 if MDAY is a valid day of the month in month MON of year
  72    YEAR, and 0 if it is not.  */
  73 static int
  74 check_mday (int year, int mon, int mday)
  75 {
  76   switch (mon)
  77     {
  78     case 0:
  79     case 2:
  80     case 4:
  81     case 6:
  82     case 7:
  83     case 9:
  84     case 11:
  85       if (mday >= 1 && mday <= 31)
  86         return 1;
  87       break;
  88     case 3:
  89     case 5:
  90     case 8:
  91     case 10:
  92       if (mday >= 1 && mday <= 30)
  93         return 1;
  94       break;
  95     case 1:
  96       if (mday >= 1 && mday <= (__isleap (year) ? 29 : 28))
  97         return 1;
  98       break;
  99     }
 100
 101   return 0;
 102 }
 103
 104
 105 int
 106 __getdate_r (const char *string, struct tm *tp)
 107 {
 108   FILE *fp;
 109   char *line;
 110   size_t len;
 111   char *datemsk;
 112   char *result = NULL;
 113   time_t timer;
 114   struct tm tm;
 115   struct stat64 st;
 116   int mday_ok = 0;
 117
 118   datemsk = getenv ("DATEMSK");
 119   if (datemsk == NULL || *datemsk == '\0')
 120     return 1;
 121
 122   if (stat64 (datemsk, &st) < 0)
 123     return 3;
 124
 125   if (!S_ISREG (st.st_mode))
 126     return 4;
 127
 128   if (__access (datemsk, R_OK) < 0)
 129     return 2;
 130
 131   /* Open the template file.  */
 132   fp = fopen (datemsk, "rc");
 133   if (fp == NULL)
 134     return 2;
 135
 136   /* No threads reading this stream.  */
 137   __fsetlocking (fp, FSETLOCKING_BYCALLER);
 138
 139   line = NULL;
 140   len = 0;
 141   do
 142     {
 143       ssize_t n;
 144
 145       n = __getline (&line, &len, fp);
 146       if (n < 0)
 147         break;
 148       if (line[n - 1] == '\n')
 149         line[n - 1] = '\0';
 150
 151       /* Do the conversion.  */
 152       tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
 153       tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
 154       tp->tm_isdst = -1;
 155       tp->tm_gmtoff = 0;
 156       tp->tm_zone = NULL;
 157       result = strptime (string, line, tp);
 158       if (result && *result == '\0')
 159         break;
 160     }
 161   while (!feof_unlocked (fp));
 162
 163   /* Free the buffer.  */
 164   free (line);
 165
 166   /* Check for errors. */
 167   if (ferror_unlocked (fp))
 168     {
 169       fclose (fp);
 170       return 5;
 171     }
 172
 173   /* Close template file.  */
 174   fclose (fp);
 175
 176   if (result == NULL || *result != '\0')
 177     return 7;
 178
 179   /* Get current time.  */
 180   time (&timer);
 181   __localtime_r (&timer, &tm);
 182
 183   /* If only the weekday is given, today is assumed if the given day
 184      is equal to the current day and next week if it is less.  */
 185   if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
 186       && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
 187     {
 188       tp->tm_year = tm.tm_year;
 189       tp->tm_mon = tm.tm_mon;
 190       tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
 191       mday_ok = 1;
 192     }
 193
 194   /* If only the month is given, the current month is assumed if the
 195      given month is equal to the current month and next year if it is
 196      less and no year is given (the first day of month is assumed if
 197      no day is given.  */
 198   if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
 199     {
 200       if (tp->tm_year == INT_MIN)
 201         tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
 202       tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
 203       mday_ok = 1;
 204     }
 205
 206   /* If no hour, minute and second are given the current hour, minute
 207      and second are assumed.  */
 208   if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
 209     {
 210       tp->tm_hour = tm.tm_hour;
 211       tp->tm_min = tm.tm_min;
 212       tp->tm_sec = tm.tm_sec;
 213     }
 214
 215   /* If no date is given, today is assumed if the given hour is
 216      greater than the current hour and tomorrow is assumed if
 217      it is less.  */
 218   if (tp->tm_hour >= 0 && tp->tm_hour <= 23
 219       && tp->tm_year == INT_MIN && tp->tm_mon == INT_MIN
 220       && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
 221     {
 222       tp->tm_year = tm.tm_year;
 223       tp->tm_mon = tm.tm_mon;
 224       tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
 225       mday_ok = 1;
 226     }
 227
 228   /* Fill in the gaps.  */
 229   if (tp->tm_year == INT_MIN)
 230     tp->tm_year = tm.tm_year;
 231   if (tp->tm_hour == INT_MIN)
 232     tp->tm_hour = 0;
 233   if (tp->tm_min == INT_MIN)
 234     tp->tm_min = 0;
 235   if (tp->tm_sec == INT_MIN)
 236     tp->tm_sec = 0;
 237
 238   /* Check if the day of month is within range, and if the time can be
 239      represented in a time_t.  We make use of the fact that the mktime
 240      call normalizes the struct tm.  */
 241   if ((!mday_ok && !check_mday (TM_YEAR_BASE + tp->tm_year, tp->tm_mon,
 242                                 tp->tm_mday))
 243       || mktime (tp) == (time_t) -1)
 244     return 8;
 245
 246   return 0;
 247 }
 248 #ifdef weak_alias
 249 weak_alias (__getdate_r, getdate_r)
 250 #endif
 251
 252
 253 struct tm *
 254 getdate (const char *string)
 255 {
 256   /* Buffer returned by getdate.  */
 257   static struct tm tmbuf;
 258   int errval = __getdate_r (string, &tmbuf);
 259
 260   if (errval != 0)
 261     {
 262       getdate_err = errval;
 263       return NULL;
 264     }
 265
 266   return &tmbuf;
 267 }