tools/flexcat/src/strptime.c

   1 /*
   2  * $Id$
   3  *
   4  * Copyright (C) 1993-1999 by Jochen Wiedmann and Marcin Orlowski
   5  * Copyright (C) 2002-2014 by the 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 == ' ')
 152         {
 153           // ignore any spaces within the day spec
 154           sc = *string++;
 155         }
 156         else if(sc >= '0' && sc <= '9')
 157         {
 158           // valid number found, add it to the day of month
 159           res->tm_mday = res->tm_mday * 10 + sc - '0';
 160           sc = *string++;
 161         }
 162         else
 163         {
 164           // unexpected character, bail out
 165           state = SDS_DONE;
 166         }
 167       }
 168       break;
 169
 170       case SDS_MONTH:
 171       {
 172         if(sc == fc)
 173         {
 174           // next separator in format string found
 175           state = SDS_DEFAULT;
 176           fc = *fmt++;
 177           sc = *string++;
 178         }
 179         else if(sc >= '0' && sc <= '9')
 180         {
 181           // valid number found, add it to the month
 182           res->tm_mon = res->tm_mon * 10 + sc - '0';
 183           sc = *string++;
 184         }
 185         else
 186         {
 187           // unexpected character, bail out
 188           state = SDS_DONE;
 189         }
 190       }
 191       break;
 192
 193       case SDS_YEAR:
 194       {
 195         if(sc == fc)
 196         {
 197           // next separator in format string found
 198           state = SDS_DEFAULT;
 199           fc = *fmt++;
 200           sc = *string++;
 201         }
 202         else if(sc >= '0' && sc <= '9')
 203         {
 204           // valid number found, add it to the year
 205           res->tm_year = res->tm_year * 10 + sc - '0';
 206           sc = *string++;
 207         }
 208         else
 209         {
 210           // unexpected character, bail out
 211           state = SDS_DONE;
 212         }
 213       }
 214       break;
 215
 216       default:
 217         // nothing to do
 218       break;
 219     }
 220   }
 221
 222   // finally check if the calculated values are correct, but only those which
 223   // were specified in the format string
 224   if((flags & FLG_MDAY) || strstr(fmt, "%d") != NULL || strstr(fmt, "%-d") != NULL || strstr(fmt, "%e") != NULL)
 225   {
 226     if(res->tm_mday >= 1 && res->tm_mday <= 31)
 227     {
 228       // nothing to adjust
 229     }
 230     else
 231     {
 232       success = 0;
 233     }
 234   }
 235   if((flags & FLG_MON) || strstr(fmt, "%m") != NULL || strstr(fmt, "%-m") != NULL)
 236   {
 237     if(res->tm_mon >= 1 && res->tm_mon <= 12)
 238     {
 239       // tm_mon counts from 0 to 11
 240       res->tm_mon--;
 241     }
 242     else
 243     {
 244       success = 0;
 245     }
 246   }
 247   if((flags & FLG_YEAR) || strstr(fmt, "%y") != NULL || strstr(fmt, "%-y") != NULL || strstr(fmt, "%Y") != NULL || strstr(fmt, "%-Y") != NULL)
 248   {
 249     if((flags & FLG_4DIGIT_YEAR) || strstr(fmt, "%Y") != NULL || strstr(fmt, "%-Y") != NULL)
 250     {
 251       if(res->tm_year >= 1900)
 252       {
 253         // tm_year counts the years from 1900
 254         res->tm_year -= 1900;
 255       }
 256       else
 257       {
 258         // year numbers less than 1900 are not supported
 259         success = 0;
 260       }
 261     }
 262     else
 263     {
 264       // 2 digit year number, must be less than 100
 265       if(res->tm_year < 100)
 266       {
 267         if(res->tm_year < 40)
 268         {
 269           // tm_year counts the years from 1900
 270           // if the year number is less than 40 we assume a year between
 271           // 2000 and 2039 instead of between 1900 and 1939 to allow a user
 272           // age of at least ~70 years.
 273           res->tm_year += 100;
 274         }
 275       }
 276       // Although we expect a two digit year number for %y we got one with more digits.
 277       // Better not fail at this even if the entered string is wrong. People tend to
 278       // forget the correct formatting.
 279       else if(res->tm_year >= 1900)
 280       {
 281         // tm_year counts the years from 1900
 282         res->tm_year -= 1900;
 283       }
 284       else
 285       {
 286         // numbers between 100 and 1899 are definitely not allowed
 287         success = 0;
 288       }
 289     }
 290   }
 291
 292   // finally check if the day value is correct
 293   if(success == 1 && (flags & FLG_MDAY))
 294   {
 295     if(res->tm_mon == 1)
 296     {
 297       // February has 29 days at most, but we don't check for leap years here
 298       if(res->tm_mday > 29)
 299       {
 300         success = 0;
 301       }
 302     }
 303     else if(res->tm_mon ==  3 ||
 304             res->tm_mon ==  5 ||
 305             res->tm_mon ==  8 ||
 306             res->tm_mon == 10)
 307     {
 308       // April, June, September and November have 30 days
 309       if(res->tm_mday > 30)
 310       {
 311         success = 0;
 312       }
 313     }
 314   }
 315
 316   return (char *)string;
 317 }
 318
 319 ///