time/getdate.c

   1 /* Convert a string representation of time to a time value.
   2    Copyright (C) 1997-2020 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    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <limits.h>
  21 #include <stdio.h>
  22 #include <stdio_ext.h>
  23 #include <stdlib.h>
  24 #include <stdbool.h>
  25 #include <string.h>
  26 #include <time.h>
  27 #include <unistd.h>
  28 #include <sys/stat.h>
  29 #include <ctype.h>
  30 #include <alloca.h>
  31
  32 #define TM_YEAR_BASE 1900
  33
  34
  35 /* Prototypes for local functions.  */
  36 static int first_wday (int year, int mon, int wday);
  37 static int check_mday (int year, int mon, int mday);
  38
  39
  40 /* Set to one of the following values to indicate an error.
  41      1  the DATEMSK environment variable is null or undefined,
  42      2  the template file cannot be opened for reading,
  43      3  failed to get file status information,
  44      4  the template file is not a regular file,
  45      5  an error is encountered while reading the template file,
  46      6  memory allication failed (not enough memory available),
  47      7  there is no line in the template that matches the input,
  48      8  invalid input specification Example: February 31 or a time is
  49         specified that can not be represented in a time_t (representing
  50         the time in seconds since 00:00:00 UTC, January 1, 1970) */
  51 int getdate_err;
  52
  53
  54 /* Returns the first weekday WDAY of month MON in the year YEAR.  */
  55 static int
  56 first_wday (int year, int mon, int wday)
  57 {
  58   struct tm tm;
  59
  60   if (wday == INT_MIN)
  61     return 1;
  62
  63   memset (&tm, 0, sizeof (struct tm));
  64   tm.tm_year = year;
  65   tm.tm_mon = mon;
  66   tm.tm_mday = 1;
  67   mktime (&tm);
  68
  69   return (1 + (wday - tm.tm_wday + 7) % 7);
  70 }
  71
  72
  73 /* Returns 1 if MDAY is a valid day of the month in month MON of year
  74    YEAR, and 0 if it is not.  */
  75 static int
  76 check_mday (int year, int mon, int mday)
  77 {
  78   switch (mon)
  79     {
  80     case 0:
  81     case 2:
  82     case 4:
  83     case 6:
  84     case 7:
  85     case 9:
  86     case 11:
  87       if (mday >= 1 && mday <= 31)
  88         return 1;
  89       break;
  90     case 3:
  91     case 5:
  92     case 8:
  93     case 10:
  94       if (mday >= 1 && mday <= 30)
  95         return 1;
  96       break;
  97     case 1:
  98       if (mday >= 1 && mday <= (__isleap (year) ? 29 : 28))
  99         return 1;
 100       break;
 101     }
 102
 103   return 0;
 104 }
 105
 106
 107 int
 108 __getdate_r (const char *string, struct tm *tp)
 109 {
 110   FILE *fp;
 111   char *line;
 112   size_t len;
 113   char *datemsk;
 114   char *result = NULL;
 115   time_t timer;
 116   struct tm tm;
 117   struct stat64 st;
 118   int mday_ok = 0;
 119
 120   datemsk = getenv ("DATEMSK");
 121   if (datemsk == NULL || *datemsk == '\0')
 122     return 1;
 123
 124   if (stat64 (datemsk, &st) < 0)
 125     return 3;
 126
 127   if (!S_ISREG (st.st_mode))
 128     return 4;
 129
 130   if (__access (datemsk, R_OK) < 0)
 131     return 2;
 132
 133   /* Open the template file.  */
 134   fp = fopen (datemsk, "rce");
 135   if (fp == NULL)
 136     return 2;
 137
 138   /* No threads reading this stream.  */
 139   __fsetlocking (fp, FSETLOCKING_BYCALLER);
 140
 141   /* Skip leading whitespace.  */
 142   while (isspace (*string))
 143     string++;
 144
 145   size_t inlen, oldlen;
 146
 147   oldlen = inlen = strlen (string);
 148
 149   /* Skip trailing whitespace.  */
 150   while (inlen > 0 && isspace (string[inlen - 1]))
 151     inlen--;
 152
 153   char *instr = NULL;
 154
 155   if (inlen < oldlen)
 156     {
 157       bool using_malloc = false;
 158
 159       if (__libc_use_alloca (inlen + 1))
 160         instr = alloca (inlen + 1);
 161       else
 162         {
 163           instr = malloc (inlen + 1);
 164           if (instr == NULL)
 165             {
 166               fclose (fp);
 167               return 6;
 168             }
 169           using_malloc = true;
 170         }
 171       memcpy (instr, string, inlen);
 172       instr[inlen] = '\0';
 173       string = instr;
 174
 175       if (!using_malloc)
 176         instr = NULL;
 177     }
 178
 179   line = NULL;
 180   len = 0;
 181   do
 182     {
 183       ssize_t n;
 184
 185       n = __getline (&line, &len, fp);
 186       if (n < 0)
 187         break;
 188       if (line[n - 1] == '\n')
 189         line[n - 1] = '\0';
 190
 191       /* Do the conversion.  */
 192       tp->tm_year = tp->tm_mon = tp->tm_mday = tp->tm_wday = INT_MIN;
 193       tp->tm_hour = tp->tm_sec = tp->tm_min = INT_MIN;
 194       tp->tm_isdst = -1;
 195       tp->tm_gmtoff = 0;
 196       tp->tm_zone = NULL;
 197       result = strptime (string, line, tp);
 198       if (result && *result == '\0')
 199         break;
 200     }
 201   while (!__feof_unlocked (fp));
 202
 203   free (instr);
 204
 205   /* Free the buffer.  */
 206   free (line);
 207
 208   /* Check for errors. */
 209   if (__ferror_unlocked (fp))
 210     {
 211       fclose (fp);
 212       return 5;
 213     }
 214
 215   /* Close template file.  */
 216   fclose (fp);
 217
 218   if (result == NULL || *result != '\0')
 219     return 7;
 220
 221   /* Get current time.  */
 222   timer = time_now ();
 223   __localtime_r (&timer, &tm);
 224
 225   /* If only the weekday is given, today is assumed if the given day
 226      is equal to the current day and next week if it is less.  */
 227   if (tp->tm_wday >= 0 && tp->tm_wday <= 6 && tp->tm_year == INT_MIN
 228       && tp->tm_mon == INT_MIN && tp->tm_mday == INT_MIN)
 229     {
 230       tp->tm_year = tm.tm_year;
 231       tp->tm_mon = tm.tm_mon;
 232       tp->tm_mday = tm.tm_mday + (tp->tm_wday - tm.tm_wday + 7) % 7;
 233       mday_ok = 1;
 234     }
 235
 236   /* If only the month is given, the current month is assumed if the
 237      given month is equal to the current month and next year if it is
 238      less and no year is given (the first day of month is assumed if
 239      no day is given.  */
 240   if (tp->tm_mon >= 0 && tp->tm_mon <= 11 && tp->tm_mday == INT_MIN)
 241     {
 242       if (tp->tm_year == INT_MIN)
 243         tp->tm_year = tm.tm_year + (((tp->tm_mon - tm.tm_mon) < 0) ? 1 : 0);
 244       tp->tm_mday = first_wday (tp->tm_year, tp->tm_mon, tp->tm_wday);
 245       mday_ok = 1;
 246     }
 247
 248   /* If no hour, minute and second are given the current hour, minute
 249      and second are assumed.  */
 250   if (tp->tm_hour == INT_MIN && tp->tm_min == INT_MIN && tp->tm_sec == INT_MIN)
 251     {
 252       tp->tm_hour = tm.tm_hour;
 253       tp->tm_min = tm.tm_min;
 254       tp->tm_sec = tm.tm_sec;
 255     }
 256
 257   /* Fill in the gaps.  */
 258   if (tp->tm_hour == INT_MIN)
 259     tp->tm_hour = 0;
 260   if (tp->tm_min == INT_MIN)
 261     tp->tm_min = 0;
 262   if (tp->tm_sec == INT_MIN)
 263     tp->tm_sec = 0;
 264
 265   /* If no date is given, today is assumed if the given hour is
 266      greater than the current hour and tomorrow is assumed if
 267      it is less.  */
 268   if (tp->tm_hour >= 0 && tp->tm_hour <= 23
 269       && tp->tm_mon == INT_MIN
 270       && tp->tm_mday == INT_MIN && tp->tm_wday == INT_MIN)
 271     {
 272       tp->tm_mon = tm.tm_mon;
 273       tp->tm_mday = tm.tm_mday + ((tp->tm_hour - tm.tm_hour) < 0 ? 1 : 0);
 274       mday_ok = 1;
 275     }
 276
 277   /* More fillers.  */
 278   if (tp->tm_year == INT_MIN)
 279     tp->tm_year = tm.tm_year;
 280   if (tp->tm_mon == INT_MIN)
 281     tp->tm_mon = tm.tm_mon;
 282
 283   /* Check if the day of month is within range, and if the time can be
 284      represented in a time_t.  We make use of the fact that the mktime
 285      call normalizes the struct tm.  */
 286   if ((!mday_ok && !check_mday (TM_YEAR_BASE + tp->tm_year, tp->tm_mon,
 287                                 tp->tm_mday))
 288       || mktime (tp) == (time_t) -1)
 289     return 8;
 290
 291   return 0;
 292 }
 293 #ifdef weak_alias
 294 weak_alias (__getdate_r, getdate_r)
 295 #endif
 296
 297
 298 struct tm *
 299 getdate (const char *string)
 300 {
 301   /* Buffer returned by getdate.  */
 302   static struct tm tmbuf;
 303   int errval = __getdate_r (string, &tmbuf);
 304
 305   if (errval != 0)
 306     {
 307       getdate_err = errval;
 308       return NULL;
 309     }
 310
 311   return &tmbuf;
 312 }