tools/flexcat/src/strptime.c

   1 /*
   2  * $Id$
   3  *
   4  * Copyright (C) 1993-1999 by Jochen Wiedmann and Marcin Orlowski
   5  * Copyright (C) 2002-2015 FlexCat Open Source Team
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or (at
  10  * your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  *
  21  */
  22
  23 #include <string.h>
  24 #include <time.h>
  25 #include <stdio.h>
  26
  27 /// strptime
  28 // parse a date string produced by strftime() and put the success in a struct tm
  29 enum ScanDateState
  30 {
  31   SDS_DEFAULT = 0,
  32   SDS_SPECIFIER,
  33   SDS_DONE,
  34   SDS_SECOND,
  35   SDS_MINUTE,
  36   SDS_HOUR,
  37   SDS_DAY_OF_MONTH,
  38   SDS_MONTH,
  39   SDS_YEAR,
  40   SDS_DAY_OF_WEEK,
  41   SDS_DAY_YEAR,
  42   SDS_IS_DST,
  43 };
  44
  45 #define FLG_SEC         (1<<0)
  46 #define FLG_MIN         (1<<1)
  47 #define FLG_HOUR        (1<<2)
  48 #define FLG_MDAY        (1<<3)
  49 #define FLG_MON         (1<<4)
  50 #define FLG_YEAR        (1<<5)
  51 #define FLG_WDAY        (1<<6)
  52 #define FLG_YDAY        (1<<7)
  53 #define FLG_ISDST       (1<<8)
  54 #define FLG_4DIGIT_YEAR (1<<9)
  55
  56 char *strptime(const char *string, const char *fmt, struct tm *res)
  57 {
  58   int success = 1;
  59   char fc;
  60   char sc;
  61   enum ScanDateState state = SDS_DEFAULT;
  62   int flags = 0;
  63
  64   // start with the first character in both strings
  65   fc = *fmt++;
  66   sc = *string++;
  67
  68   while(state != SDS_DONE)
  69   {
  70     if(fc == '\0' && sc == '\0')
  71       state = SDS_DONE;
  72
  73     switch(state)
  74     {
  75       case SDS_DEFAULT:
  76       {
  77         if(fc == '%')
  78         {
  79           state = SDS_SPECIFIER;
  80           fc = *fmt++;
  81         }
  82         else
  83         {
  84           // the format string seems to be malformed, bail out
  85           state = SDS_DONE;
  86         }
  87       }
  88       break;
  89
  90       case SDS_SPECIFIER:
  91       {
  92         switch(fc)
  93         {
  94           case 'd': // %d  - day number with leading zeros (01-31)
  95           case 'e': // %e  - day number with leading spaces ( 1-31)
  96           {
  97             flags |= FLG_MDAY;
  98             state = SDS_DAY_OF_MONTH;
  99             fc = *fmt++;
 100           }
 101           break;
 102
 103           case 'm': // %m  - month number with leading zeros (01-12)
 104           {
 105             flags |= FLG_MON;
 106             state = SDS_MONTH;
 107             fc = *fmt++;
 108           }
 109           break;
 110
 111           case 'Y': // %Y  - year using four digits with leading zeros
 112           {
 113             flags |= FLG_4DIGIT_YEAR;
 114           }
 115           // we fall through here
 116
 117           case 'y': // %y  - year using two digits with leading zeros (00-99)
 118           {
 119             flags |= FLG_YEAR;
 120             state = SDS_YEAR;
 121             fc = *fmt++;
 122           }
 123           break;
 124
 125           case '-':
 126           {
 127             // ignore any switches between with/without leading zeros/spaces
 128             fc = *fmt++;
 129           }
 130           break;
 131
 132           default:
 133           {
 134             // unknown specifier, bail out
 135             state = SDS_DONE;
 136           }
 137           break;
 138         }
 139       }
 140       break;
 141
 142       case SDS_DAY_OF_MONTH:
 143       {
 144         if(sc == fc)
 145         {
 146           // next separator in format string found
 147           state = SDS_DEFAULT;
 148           fc = *fmt++;
 149           sc = *string++;
 150         }
 151         else if(sc >= '0' && sc <= '9')
 152         {
 153           // valid number found, add it to the day of month
 154           res->tm_mday = res->tm_mday * 10 + sc - '0';
 155           sc = *string++;
 156         }
 157         else
 158         {
 159           // unexpected character, bail out
 160           state = SDS_DONE;
 161         }
 162       }
 163       break;
 164
 165       case SDS_MONTH:
 166       {
 167         if(sc == fc)
 168         {
 169           // next separator in format string found
 170           state = SDS_DEFAULT;
 171           fc = *fmt++;
 172           sc = *string++;
 173         }
 174         else if(sc >= '0' && sc <= '9')
 175         {
 176           // valid number found, add it to the month
 177           res->tm_mon = res->tm_mon * 10 + sc - '0';
 178           sc = *string++;
 179         }
 180         else
 181         {
 182           // unexpected character, bail out
 183           state = SDS_DONE;
 184         }
 185       }
 186       break;
 187
 188       case SDS_YEAR:
 189       {
 190         if(sc == fc)
 191         {
 192           // next separator in format string found
 193           state = SDS_DEFAULT;
 194           fc = *fmt++;
 195           sc = *string++;
 196         }
 197         else if(sc >= '0' && sc <= '9')
 198         {
 199           // valid number found, add it to the year
 200           res->tm_year = res->tm_year * 10 + sc - '0';
 201           sc = *string++;
 202         }
 203         else
 204         {
 205           // unexpected character, bail out
 206           state = SDS_DONE;
 207         }
 208       }
 209       break;
 210
 211       default:
 212         // nothing to do
 213       break;
 214     }
 215   }
 216
 217   // finally check if the calculated values are correct, but only those which
 218   // were specified in the format string
 219   if((flags & FLG_MDAY) || strstr(fmt, "%d") != NULL || strstr(fmt, "%-d") != NULL || strstr(fmt, "%e") != NULL)
 220   {
 221     if(res->tm_mday >= 1 && res->tm_mday <= 31)
 222     {
 223       // nothing to adjust
 224     }
 225     else
 226     {
 227       success = 0;
 228     }
 229   }
 230   if((flags & FLG_MON) || strstr(fmt, "%m") != NULL || strstr(fmt, "%-m") != NULL)
 231   {
 232     if(res->tm_mon >= 1 && res->tm_mon <= 12)
 233     {
 234       // tm_mon counts from 0 to 11
 235       res->tm_mon--;
 236     }
 237     else
 238     {
 239       success = 0;
 240     }
 241   }
 242   if((flags & FLG_YEAR) || strstr(fmt, "%y") != NULL || strstr(fmt, "%-y") != NULL || strstr(fmt, "%Y") != NULL || strstr(fmt, "%-Y") != NULL)
 243   {
 244     if((flags & FLG_4DIGIT_YEAR) || strstr(fmt, "%Y") != NULL || strstr(fmt, "%-Y") != NULL)
 245     {
 246       if(res->tm_year >= 1900)
 247       {
 248         // tm_year counts the years from 1900
 249         res->tm_year -= 1900;
 250       }
 251       else
 252       {
 253         // year numbers less than 1900 are not supported
 254         success = 0;
 255       }
 256     }
 257     else
 258     {
 259       // 2 digit year number, must be less than 100
 260       if(res->tm_year < 100)
 261       {
 262         if(res->tm_year < 40)
 263         {
 264           // tm_year counts the years from 1900
 265           // if the year number is less than 40 we assume a year between
 266           // 2000 and 2039 instead of between 1900 and 1939 to allow a user
 267           // age of at least ~70 years.
 268           res->tm_year += 100;
 269         }
 270       }
 271       // Although we expect a two digit year number for %y we got one with more digits.
 272       // Better not fail at this even if the entered string is wrong. People tend to
 273       // forget the correct formatting.
 274       else if(res->tm_year >= 1900)
 275       {
 276         // tm_year counts the years from 1900
 277         res->tm_year -= 1900;
 278       }
 279       else
 280       {
 281         // numbers between 100 and 1899 are definitely not allowed
 282         success = 0;
 283       }
 284     }
 285   }
 286
 287   // finally check if the day value is correct
 288   if(success == 1 && (flags & FLG_MDAY))
 289   {
 290     if(res->tm_mon == 1)
 291     {
 292       // February has 29 days at most, but we don't check for leap years here
 293       if(res->tm_mday > 29)
 294       {
 295         success = 0;
 296       }
 297     }
 298     else if(res->tm_mon ==  3 ||
 299             res->tm_mon ==  5 ||
 300             res->tm_mon ==  8 ||
 301             res->tm_mon == 10)
 302     {
 303       // April, June, September and November have 30 days
 304       if(res->tm_mday > 30)
 305       {
 306         success = 0;
 307       }
 308     }
 309   }
 310
 311   return (char *)string;
 312 }
 313
 314 ///