usr.bin/rcs/src/maketime.c

   1 #
   2 /*
   3  * MAKETIME             derive 32-bit time value from TM structure.
   4  *
   5  * Usage:
   6  *      long t,maketime();
   7  *      struct tm *tp;  Pointer to TM structure from <time.h>
   8  *                      NOTE: this must be extended version!!!
   9  *      t = maketime(tp);
  10  *
  11  * Returns:
  12  *      0 if failure; parameter out of range or nonsensical.
  13  *      else long time-value.
  14  * Notes:
  15  *      This code is quasi-public; it may be used freely in like software.
  16  *      It is not to be sold, nor used in licensed software without
  17  *      permission of the author.
  18  *      For everyone's benefit, please report bugs and improvements!
  19  *      Copyright 1981 by Ken Harrenstien, SRI International.
  20  *      (ARPANET: KLH @ SRI)
  21  */
  22 #ifndef lint
  23 static char rcsid[]= "$Id: maketime.c,v 1.1 1993/03/21 09:58:06 cgd Exp $";
  24 #endif
  25 /* $Log:        maketime.c,v $
  26  * Revision 1.8  88/11/08  13:54:53  narten
  27  * allow negative timezones (-24h <= x <= 24h)
  28  *
  29  * Revision 1.7  88/11/08  12:02:24  narten
  30  * changes from  eggert@sm.unisys.com (Paul Eggert)
  31  *
  32  * Revision 1.7  88/08/28  14:47:52  eggert
  33  * Allow cc -R.  Remove unportable "#endif XXX"s.
  34  *
  35  * Revision 1.6  87/12/18  17:05:58  narten
  36  * include rcsparam.h
  37  *
  38  * Revision 1.5  87/12/18  11:35:51  narten
  39  * maketime.c: fixed USG code - you have tgo call "tzset" in order to have
  40  * "timezone" set. ("localtime" calls it, but it's probably better not to
  41  * count on "localtime" having been called.)
  42  *
  43  * Revision 1.4  87/10/18  10:26:57  narten
  44  * Updating version numbers. Changes relative to 1.0 are actually
  45  * relative to 1.2
  46  *
  47  * Revision 1.3  87/09/24  13:58:45  narten
  48  * Sources now pass through lint (if you ignore printf/sprintf/fprintf
  49  * warnings)
  50  *
  51  * Revision 1.2  87/03/27  14:21:48  jenkins
  52  * Port to suns
  53  *
  54  * Revision 1.1  84/01/23  14:50:04  kcs
  55  * Initial revision
  56  *
  57  * Revision 1.2  83/12/05  10:12:56  wft
  58  * added cond. compilation for USG Unix; long timezone;
  59  *
  60  * Revision 1.1  82/05/06  11:38:00  wft
  61  * Initial revision
  62  *
  63  */
  64
  65
  66 #include "rcsbase.h"
  67 #include "time.h"
  68
  69 int daytb[] = {   /* # days in year thus far, indexed by month (0-12!!) */
  70         0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
  71 };
  72
  73 struct tm *localtime();
  74 long    time();
  75
  76 long maketime(atm)
  77 struct tm *atm;
  78 {       register struct tm *tp;
  79         register int i;
  80         int year, yday, mon, day, hour, min, sec, zone, dst, leap;
  81         long tres, curtim;
  82
  83         VOID time(&curtim);
  84         tp = localtime(&curtim);        /* Get breakdowns of current time */
  85         year = tp->tm_year;             /* Use to set up defaults */
  86         mon = tp->tm_mon;
  87         day = tp->tm_mday;
  88
  89
  90 #ifdef DEBUG
  91 printf("first YMD: %d %d %d, T=%ld\n",year,mon,day,tres);
  92 #endif
  93         tp = atm;
  94
  95         /* First must find date, using specified year, month, day.
  96          * If one of these is unspecified, it defaults either to the
  97          * current date (if no more global spec was given) or to the
  98          * zero-value for that spec (i.e. a more global spec was seen).
  99          * Start with year... note 32 bits can only handle 135 years.
 100          */
 101         if(tp->tm_year != TMNULL)
 102           {     if((year = tp->tm_year) >= 1900)        /* Allow full yr # */
 103                         year -= 1900;                   /* by making kosher */
 104                 mon = 0;                /* Since year was given, default */
 105                 day = 1;                /* for remaining specs is zero */
 106           }
 107         if(year < 70 || 70+134 < year ) /* Check range */
 108                 return(0);              /* ERR: year out of range */
 109         leap = year&03 ? 0 : 1;         /* See if leap year */
 110         year -= 70;                     /* UNIX time starts at 1970 */
 111
 112         /*
 113          * Find day of year.
 114          * YDAY is used only if it exists and either the month or day-of-month
 115          * is missing.
 116          */
 117         if (tp->tm_yday != TMNULL
 118          && (tp->tm_mon == TMNULL || tp->tm_mday == TMNULL))
 119                 yday = tp->tm_yday;
 120         else
 121           {     if(tp->tm_mon  != TMNULL)
 122                   {     mon = tp->tm_mon;       /* Month was specified */
 123                         day = 1;                /* so set remaining default */
 124                   }
 125                 if(mon < 0 || 11 < mon) return(0);      /* ERR: bad month */
 126                 if(tp->tm_mday != TMNULL) day = tp->tm_mday;
 127                 if(day < 1
 128                  || (((daytb[mon+1]-daytb[mon]) < day)
 129                         && (day!=29 || mon!=1 || !leap) ))
 130                                 return(0);              /* ERR: bad day */
 131                 yday = daytb[mon]       /* Add # of days in months so far */
 132                   + ((leap              /* Leap year, and past Feb?  If */
 133                       && mon>1)? 1:0)   /* so, add leap day for this year */
 134                   + day-1;              /* And finally add # days this mon */
 135
 136                 if (tp->tm_yday != TMNULL       /* Confirm that YDAY correct */
 137                  && tp->tm_yday != yday) return(0);     /* ERR: conflict */
 138           }
 139         if(yday < 0 || (leap?366:365) <= yday)
 140                 return(0);              /* ERR: bad YDAY or maketime bug */
 141
 142         tres = year*365                 /* Get # days of years so far */
 143                 + ((year+1)>>2)         /* plus # of leap days since 1970 */
 144                 + yday;                 /* and finally add # days this year */
 145
 146         if((i = tp->tm_wday) != TMNULL) /* Check WDAY if present */
 147                 if(i < 0 || 6 < i       /* Ensure within range */
 148                   || i != (tres+4)%7)   /* Matches? Jan 1,1970 was Thu = 4 */
 149                         return(0);      /* ERR: bad WDAY */
 150
 151 #ifdef DEBUG
 152 printf("YMD: %d %d %d, T=%ld\n",year,mon,day,tres);
 153 #endif
 154         /*
 155          * Now determine time.  If not given, default to zeros
 156          * (since time is always the least global spec)
 157          */
 158         tres *= 86400L;                 /* Get # seconds (24*60*60) */
 159         hour = min = sec = 0;
 160         if(tp->tm_hour != TMNULL) hour = tp->tm_hour;
 161         if(tp->tm_min  != TMNULL) min  = tp->tm_min;
 162         if(tp->tm_sec  != TMNULL) sec  = tp->tm_sec;
 163         if( min < 0 || 60 <= min
 164          || sec < 0 || 60 <= sec) return(0);    /* ERR: MS out of range */
 165         if(hour < 0 || 24 <= hour)
 166                 if(hour != 24 || (min+sec) !=0) /* Allow 24:00 */
 167                         return(0);              /* ERR: H out of range */
 168
 169         /* confirm AM/PM if there */
 170         switch(tp->tm_ampm)
 171           {     case 0: case TMNULL:    /* Ignore these values */
 172                         break;
 173                 case 1:                 /* AM */
 174                 case 2:                 /* PM */
 175                         if(hour > 12) return(0);  /* ERR: hrs 13-23 bad */
 176                         if(hour ==12) hour = 0; /* Modulo 12 */
 177                         if(tp->tm_ampm == 2)    /* If PM, then */
 178                                 hour += 12;     /*   get 24-hour time */
 179                         break;
 180                 default: return(0);     /* ERR: illegal TM_AMPM value */
 181           }
 182
 183         tres += sec + 60L*(min + 60L*hour);     /* Add in # secs of time */
 184
 185 #ifdef DEBUG
 186 printf("HMS: %d %d %d T=%ld\n",hour,min,sec,tres);
 187 #endif
 188         /*
 189          * We now have the GMT date/time and must make final
 190          * adjustment for the specified time zone.  If none is specified,
 191          * the local time-zone is assumed.
 192          */
 193         if((zone = tp->tm_zon) == TMNULL        /* If unspecified */
 194          || (zone == 1))                        /* or local-zone requested */
 195                 zone = localzone();             /* then set to local zone */
 196         if(zone < -24*60 || 24*60 <= zone)
 197                 return(0);                      /* ERR: zone out of range */
 198
 199         /* See if must apply Daylight Saving Time shift.
 200          * Note that if DST is specified, validity is not checked.
 201          */
 202         if((dst = tp->tm_isdst) == TMNULL)      /* Must we figure it out? */
 203           {     curtim = tres +localzone()*60L; /* Yuck.  Get equiv local */
 204                 dst = localtime(&curtim)->tm_isdst;     /* time, and ask. */
 205           }
 206         tres += zone*60L -(dst?3600:0); /* Add in # seconds of zone adj */
 207
 208         return(tres);
 209 }