time/getdate.c

   1 /* Convert a string representation of time to a time value.
   2    Copyright (C) 1997-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <limits.h>
  20 #include <stdio.h>
  21 #include <stdio_ext.h>
  22 #include <stdlib.h>
  23 #include <stdbool.h>
  24 #include <string.h>
  25 #include <time.h>
  26 #include <unistd.h>
  27 #include <sys/stat.h>
  28 #include <ctype.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   __time64_t timer;
 114   struct tm tm;
 115   struct __stat64_t64 st;
 116   bool mday_ok = false;
 117   bool found = false;
 118
 119   datemsk = getenv ("DATEMSK");
 120   if (datemsk == NULL || *datemsk == '\0')
 121     return 1;
 122
 123   if (__stat64_time64 (datemsk, &st) < 0)
 124     return 3;
 125
 126   if (!S_ISREG (st.st_mode))
 127     return 4;
 128
 129   if (__access (datemsk, R_OK) < 0)
 130     return 2;
 131
 132   /* Open the template file.  */
 133   fp = fopen (datemsk, "rce");
 134   if (fp == NULL)
 135     return 2;
 136
 137   /* No threads reading this stream.  */
 138   __fsetlocking (fp, FSETLOCKING_BYCALLER);
 139
 140   /* Skip leading whitespace.  */
 141   while (isspace (*string))
 142     string++;
 143
 144   size_t inlen, oldlen;
 145
 146   oldlen = inlen = strlen (string);
 147
 148   /* Skip trailing whitespace.  */
 149   while (inlen > 0 && isspace (string[inlen - 1]))
 150     inlen--;
 151
 152   char *instr = NULL;
 153
 154   if (inlen < oldlen)
 155     {
 156       instr = __strndup(string, inlen);
 157       if (instr == NULL)
 158         {
 159           fclose(fp);
 160           return 6;
 161         }
 162
 163       string = instr;
 164     }
 165
 166   line = NULL;
 167   len = 0;
 168   do
 169     {
 170       ssize_t n;
 171
 172       n = __getline (&line, &len, fp);
 173       if (n < 0)
 174         break;
 175       if (line[n - 1] == '\n')
 176         line[n - 1] = '\0';
 177
 178       /* Do the conversion.  */
 179       tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
 180       tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
 181       tp->tm_isdst = -1;
 182       tp->tm_gmtoff = 0;
 183       tp->tm_zone = NULL;
 184       result = strptime (string, line, tp);
 185       if ((found = (result && *result == '\0')))
 186         break;
 187     }
 188   while (!__feof_unlocked (fp));
 189
 190   free (instr);
 191
 192   /* Free the buffer.  */
 193   free (line);
 194
 195   /* Check for errors. */
 196   if (__ferror_unlocked (fp))
 197     {
 198       fclose (fp);
 199       return 5;
 200     }
 201
 202   /* Close template file.  */
 203   fclose (fp);
 204
 205   if (!found)
 206     return 7;
 207
 208   /* Get current time.  */
 209   timer = time64_now ();
 210   __localtime64_r (&timer, &tm);
 211
 212   /* If only the weekday is given, today is assumed if the given day
 213      is equal to the current day and next week if it is less.  */
 214   if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
 215       && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
 216     {
 217       tp->tm_year = tm.tm_year;
 218       tp->tm_mon = tm.tm_mon;
 219       tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
 220       mday_ok = true;
 221     }
 222
 223   /* If only the month is given, the current month is assumed if the
 224      given month is equal to the current month and next year if it is
 225      less and no year is given (the first day of month is assumed if
 226      no day is given.  */
 227   if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
 228     {
 229       if (tp->tm_year == INT_MIN)
 230         tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
 231       tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
 232       mday_ok = true;
 233     }
 234
 235   /* If no hour, minute and second are given the current hour, minute
 236      and second are assumed.  */
 237   if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
 238     {
 239       tp->tm_hour = tm.tm_hour;
 240       tp->tm_min = tm.tm_min;
 241       tp->tm_sec = tm.tm_sec;
 242     }
 243
 244   /* Fill in the gaps.  */
 245   if (tp->tm_hour == INT_MIN)
 246     tp->tm_hour = 0;
 247   if (tp->tm_min == INT_MIN)
 248     tp->tm_min = 0;
 249   if (tp->tm_sec == INT_MIN)
 250     tp->tm_sec = 0;
 251
 252   /* If no date is given, today is assumed if the given hour is
 253      greater than the current hour and tomorrow is assumed if
 254      it is less.  */
 255   if (tp->tm_hour >= 0 && tp->tm_hour <= 23
 256       && tp->tm_mon == INT_MIN
 257       && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
 258     {
 259       tp->tm_mon = tm.tm_mon;
 260       tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
 261       mday_ok = 1;
 262     }
 263
 264   /* More fillers.  */
 265   if (tp->tm_year == INT_MIN)
 266     tp->tm_year = tm.tm_year;
 267   if (tp->tm_mon == INT_MIN)
 268     tp->tm_mon = tm.tm_mon;
 269
 270   /* Check if the day of month is within range, and if the time can be
 271      represented in a time_t.  We make use of the fact that the mktime
 272      call normalizes the struct tm.  */
 273   if ((!mday_ok && !check_mday (TM_YEAR_BASE + tp->tm_year, tp->tm_mon,
 274                                 tp->tm_mday))
 275       || __mktime64 (tp) == (time_t) -1)
 276     return 8;
 277
 278   return 0;
 279 }
 280 weak_alias (__getdate_r, getdate_r)
 281 libc_hidden_def (__getdate_r)
 282
 283 struct tm *
 284 getdate (const char *string)
 285 {
 286   /* Buffer returned by getdate.  */
 287   static struct tm tmbuf;
 288   int errval = __getdate_r (string, &tmbuf);
 289
 290   if (errval != 0)
 291     {
 292       getdate_err = errval;
 293       return NULL;
 294     }
 295
 296   return &tmbuf;
 297 }