text: /* 
   *  parsetime.c - parse time for at(1)
   *  Copyright (C) 1993, 1994  Thomas Koenig
   *
   *  modifications for English-language times
   *  Copyright (C) 1993  David Parsons
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. The name of the author(s) may not be used to endorse or promote
   *    products derived from this software without specific prior written
   *    permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   *  at [NOW] PLUS NUMBER MINUTES|HOURS|DAYS|WEEKS
   *     /NUMBER [DOT NUMBER] [AM|PM]\ /[MONTH NUMBER [NUMBER]]             \
   *     |NOON                       | |[TOMORROW]                          |
   *     |MIDNIGHT                   | |[DAY OF WEEK]                       |
   *     \TEATIME                    / |NUMBER [SLASH NUMBER [SLASH NUMBER]]|
   *                                   \PLUS NUMBER MINUTES|HOURS|DAYS|WEEKS/
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD$");
  
  /* System Headers */
  
  #include <sys/types.h>
  #include <ctype.h>
  #include <err.h>
  #include <errno.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <time.h>
  #include <unistd.h>
  #ifndef __FreeBSD__
  #include <getopt.h>
  #endif
  
  /* Local headers */
  
  #include "at.h"
  #include "panic.h"
  #include "parsetime.h"
  
  
  /* Structures and unions */
  
  enum {	/* symbols */
      MIDNIGHT, NOON, TEATIME,
      PM, AM, TOMORROW, TODAY, NOW,
      MINUTES, HOURS, DAYS, WEEKS, MONTHS, YEARS,
      NUMBER, PLUS, MINUS, DOT, SLASH, ID, JUNK,
      JAN, FEB, MAR, APR, MAY, JUN,
      JUL, AUG, SEP, OCT, NOV, DEC,
      SUN, MON, TUE, WED, THU, FRI, SAT
      };
  
  /* parse translation table - table driven parsers can be your FRIEND!
   */
  static const struct {
      const char *name;	/* token name */
      int value;	/* token id */
      int plural;	/* is this plural? */
  } Specials[] = {
      { "midnight", MIDNIGHT,0 },	/* 00:00:00 of today or tomorrow */
      { "noon", NOON,0 },		/* 12:00:00 of today or tomorrow */
      { "teatime", TEATIME,0 },	/* 16:00:00 of today or tomorrow */
      { "am", AM,0 },		/* morning times for 0-12 clock */
      { "pm", PM,0 },		/* evening times for 0-12 clock */
      { "tomorrow", TOMORROW,0 },	/* execute 24 hours from time */
      { "today", TODAY, 0 },	/* execute today - don't advance time */
      { "now", NOW,0 },		/* opt prefix for PLUS */
  
      { "minute", MINUTES,0 },	/* minutes multiplier */
      { "minutes", MINUTES,1 },	/* (pluralized) */
      { "hour", HOURS,0 },	/* hours ... */
      { "hours", HOURS,1 },	/* (pluralized) */
      { "day", DAYS,0 },		/* days ... */
      { "days", DAYS,1 },		/* (pluralized) */
      { "week", WEEKS,0 },	/* week ... */
      { "weeks", WEEKS,1 },	/* (pluralized) */
      { "month", MONTHS,0 },	/* month ... */
      { "months", MONTHS,1 },	/* (pluralized) */
      { "year", YEARS,0 },	/* year ... */
      { "years", YEARS,1 },	/* (pluralized) */
      { "jan", JAN,0 },
      { "feb", FEB,0 },
      { "mar", MAR,0 },
      { "apr", APR,0 },
      { "may", MAY,0 },
      { "jun", JUN,0 },
      { "jul", JUL,0 },
      { "aug", AUG,0 },
      { "sep", SEP,0 },
      { "oct", OCT,0 },
      { "nov", NOV,0 },
      { "dec", DEC,0 },
      { "january", JAN,0 },
      { "february", FEB,0 },
      { "march", MAR,0 },
      { "april", APR,0 },
      { "may", MAY,0 },
      { "june", JUN,0 },
      { "july", JUL,0 },
      { "august", AUG,0 },
      { "september", SEP,0 },
      { "october", OCT,0 },
      { "november", NOV,0 },
      { "december", DEC,0 },
      { "sunday", SUN, 0 },
      { "sun", SUN, 0 },
      { "monday", MON, 0 },
      { "mon", MON, 0 },
      { "tuesday", TUE, 0 },
      { "tue", TUE, 0 },
      { "wednesday", WED, 0 },
      { "wed", WED, 0 },
      { "thursday", THU, 0 },
      { "thu", THU, 0 },
      { "friday", FRI, 0 },
      { "fri", FRI, 0 },
      { "saturday", SAT, 0 },
      { "sat", SAT, 0 },
  } ;
  
  /* File scope variables */
  
  static char **scp;	/* scanner - pointer at arglist */
  static char scc;	/* scanner - count of remaining arguments */
  static char *sct;	/* scanner - next char pointer in current argument */
  static int need;	/* scanner - need to advance to next argument */
  
  static char *sc_token;	/* scanner - token buffer */
  static size_t sc_len;   /* scanner - length of token buffer */
  static int sc_tokid;	/* scanner - token id */
  static int sc_tokplur;	/* scanner - is token plural? */
  
  /* Local functions */
  
  /*
   * parse a token, checking if it's something special to us
   */
  static int
  parse_token(char *arg)
  {
      size_t i;
  
      for (i=0; i<(sizeof Specials/sizeof Specials[0]); i++)
  	if (strcasecmp(Specials[i].name, arg) == 0) {
  	    sc_tokplur = Specials[i].plural;
  	    return sc_tokid = Specials[i].value;
  	}
  
      /* not special - must be some random id */
      return ID;
  } /* parse_token */
  
  
  /*
   * init_scanner() sets up the scanner to eat arguments
   */
  static void
  init_scanner(int argc, char **argv)
  {
      scp = argv;
      scc = argc;
      need = 1;
      sc_len = 1;
      while (argc-- > 0)
  	sc_len += strlen(*argv++);
  
      if ((sc_token = malloc(sc_len)) == NULL)
  	errx(EXIT_FAILURE, "virtual memory exhausted");
  } /* init_scanner */
  
  /*
   * token() fetches a token from the input stream
   */
  static int
  token(void)
  {
      int idx;
  
      while (1) {
  	memset(sc_token, 0, sc_len);
  	sc_tokid = EOF;
  	sc_tokplur = 0;
  	idx = 0;
  
  	/* if we need to read another argument, walk along the argument list;
  	 * when we fall off the arglist, we'll just return EOF forever
  	 */
  	if (need) {
  	    if (scc < 1)
  		return sc_tokid;
  	    sct = *scp;
  	    scp++;
  	    scc--;
  	    need = 0;
  	}
  	/* eat whitespace now - if we walk off the end of the argument,
  	 * we'll continue, which puts us up at the top of the while loop
  	 * to fetch the next argument in
  	 */
  	while (isspace(*sct))
  	    ++sct;
  	if (!*sct) {
  	    need = 1;
  	    continue;
  	}
  
  	/* preserve the first character of the new token
  	 */
  	sc_token[0] = *sct++;
  
  	/* then see what it is
  	 */
  	if (isdigit(sc_token[0])) {
  	    while (isdigit(*sct))
  		sc_token[++idx] = *sct++;
  	    sc_token[++idx] = 0;
  	    return sc_tokid = NUMBER;
  	}
  	else if (isalpha(sc_token[0])) {
  	    while (isalpha(*sct))
  		sc_token[++idx] = *sct++;
  	    sc_token[++idx] = 0;
  	    return parse_token(sc_token);
  	}
  	else if (sc_token[0] == ':' || sc_token[0] == '.')
  	    return sc_tokid = DOT;
  	else if (sc_token[0] == '+')
  	    return sc_tokid = PLUS;
  	else if (sc_token[0] == '-')
  	    return sc_tokid = MINUS;
  	else if (sc_token[0] == '/')
  	    return sc_tokid = SLASH;
  	else
  	    return sc_tokid = JUNK;
      } /* while (1) */
  } /* token */
  
  
  /*
   * plonk() gives an appropriate error message if a token is incorrect
   */
  static void
  plonk(int tok)
  {
      panic((tok == EOF) ? "incomplete time"
  		       : "garbled time");
  } /* plonk */
  
  
  /* 
   * expect() gets a token and dies most horribly if it's not the token we want
   */
  static void
  expect(int desired)
  {
      if (token() != desired)
  	plonk(sc_tokid);	/* and we die here... */
  } /* expect */
  
  
  /*
   * plus_or_minus() holds functionality common to plus() and minus()
   */
  static void
  plus_or_minus(struct tm *tm, int delay)
  {
      int expectplur;
  
      expectplur = (delay != 1 && delay != -1) ? 1 : 0;
  
      switch (token()) {
      case YEARS:
  	    tm->tm_year += delay;
  	    break;
      case MONTHS:
  	    tm->tm_mon += delay;
  	    break;
      case WEEKS:
  	    delay *= 7;
      case DAYS:
  	    tm->tm_mday += delay;
  	    break;
      case HOURS:
  	    tm->tm_hour += delay;
  	    break;
      case MINUTES:
  	    tm->tm_min += delay;
  	    break;
      default:
      	    plonk(sc_tokid);
  	    break;
      }
  
      if (expectplur != sc_tokplur)
  	warnx("pluralization is wrong");
  
      tm->tm_isdst = -1;
      if (mktime(tm) < 0)
  	plonk(sc_tokid);
  } /* plus_or_minus */
  
  
  /*
   * plus() parses a now + time
   *
   *  at [NOW] PLUS NUMBER [MINUTES|HOURS|DAYS|WEEKS|MONTHS|YEARS]
   *
   */
  static void
  plus(struct tm *tm)
  {
      int delay;
  
      expect(NUMBER);
  
      delay = atoi(sc_token);
      plus_or_minus(tm, delay);
  } /* plus */
  
  
  /*
   * minus() is like plus but can not be used with NOW
   */
  static void
  minus(struct tm *tm)
  {
      int delay;
  
      expect(NUMBER);
  
      delay = -atoi(sc_token);
      plus_or_minus(tm, delay);
  } /* minus */
  
  
  /*
   * tod() computes the time of day
   *     [NUMBER [DOT NUMBER] [AM|PM]]
   */
  static void
  tod(struct tm *tm)
  {
      int hour, minute = 0;
      int tlen;
  
      hour = atoi(sc_token);
      tlen = strlen(sc_token);
  
      /* first pick out the time of day - if it's 4 digits, we assume
       * a HHMM time, otherwise it's HH DOT MM time
       */
      if (token() == DOT) {
  	expect(NUMBER);
  	minute = atoi(sc_token);
  	if (minute > 59)
  	    panic("garbled time");
  	token();
      }
      else if (tlen == 4) {
  	minute = hour%100;
  	if (minute > 59)
  	    panic("garbled time");
  	hour = hour/100;
      }
  
      /* check if an AM or PM specifier was given
       */
      if (sc_tokid == AM || sc_tokid == PM) {
  	if (hour > 12)
  	    panic("garbled time");
  
  	if (sc_tokid == PM) {
  	    if (hour != 12)	/* 12:xx PM is 12:xx, not 24:xx */
  			hour += 12;
  	} else {
  	    if (hour == 12)	/* 12:xx AM is 00:xx, not 12:xx */
  			hour = 0;
  	}
  	token();
      }
      else if (hour > 23)
  	panic("garbled time");
  
      /* if we specify an absolute time, we don't want to bump the day even
       * if we've gone past that time - but if we're specifying a time plus
       * a relative offset, it's okay to bump things
       */
      if ((sc_tokid == EOF || sc_tokid == PLUS || sc_tokid == MINUS) && 
  	tm->tm_hour > hour) {
  	tm->tm_mday++;
  	tm->tm_wday++;
      }
  
      tm->tm_hour = hour;
      tm->tm_min = minute;
      if (tm->tm_hour == 24) {
  	tm->tm_hour = 0;
  	tm->tm_mday++;
      }
  } /* tod */
  
  
  /*
   * assign_date() assigns a date, wrapping to next year if needed
   */
  static void
  assign_date(struct tm *tm, long mday, long mon, long year)
  {
  
     /*
      * Convert year into tm_year format (year - 1900).
      * We may be given the year in 2 digit, 4 digit, or tm_year format.
      */
      if (year != -1) {
  	if (year >= 1900)
  		year -= 1900;   /* convert from 4 digit year */
  	else if (year < 100) {
  		/* convert from 2 digit year */
  		struct tm *lt;
  		time_t now;
  
  		time(&now);
  		lt = localtime(&now);
  
  		/* Convert to tm_year assuming current century */
  		year += (lt->tm_year / 100) * 100;
  
  		if (year == lt->tm_year - 1) year++;
  		else if (year < lt->tm_year)
  			year += 100;    /* must be in next century */
  	}
      }
  
      if (year < 0 &&
  	(tm->tm_mon > mon ||(tm->tm_mon == mon && tm->tm_mday > mday)))
  	year = tm->tm_year + 1;
  
      tm->tm_mday = mday;
      tm->tm_mon = mon;
  
      if (year >= 0)
  	tm->tm_year = year;
  } /* assign_date */
  
  
  /* 
   * month() picks apart a month specification
   *
   *  /[<month> NUMBER [NUMBER]]           \
   *  |[TOMORROW]                          |
   *  |[DAY OF WEEK]                       |
   *  |NUMBER [SLASH NUMBER [SLASH NUMBER]]|
   *  \PLUS NUMBER MINUTES|HOURS|DAYS|WEEKS/
   */
  static void
  month(struct tm *tm)
  {
      long year= (-1);
      long mday = 0, wday, mon;
      int tlen;
  
      switch (sc_tokid) {
      case PLUS:
  	    plus(tm);
  	    break;
      case MINUS:
  	    minus(tm);
  	    break;
  
      case TOMORROW:
  	    /* do something tomorrow */
  	    tm->tm_mday ++;
  	    tm->tm_wday ++;
      case TODAY:	/* force ourselves to stay in today - no further processing */
  	    token();
  	    break;
  
      case JAN: case FEB: case MAR: case APR: case MAY: case JUN:
      case JUL: case AUG: case SEP: case OCT: case NOV: case DEC:
  	    /* do month mday [year]
  	     */
  	    mon = (sc_tokid-JAN);
  	    expect(NUMBER);
  	    mday = atol(sc_token);
  	    if (token() == NUMBER) {
  		year = atol(sc_token);
  		token();
  	    }
  	    assign_date(tm, mday, mon, year);
  	    break;
  
      case SUN: case MON: case TUE:
      case WED: case THU: case FRI:
      case SAT:
  	    /* do a particular day of the week
  	     */
  	    wday = (sc_tokid-SUN);
  
  	    mday = tm->tm_mday;
  
  	    /* if this day is < today, then roll to next week
  	     */
  	    if (wday < tm->tm_wday)
  		mday += 7 - (tm->tm_wday - wday);
  	    else
  		mday += (wday - tm->tm_wday);
  
  	    tm->tm_wday = wday;
  
  	    assign_date(tm, mday, tm->tm_mon, tm->tm_year);
  	    break;
  
      case NUMBER:
  	    /* get numeric MMDDYY, mm/dd/yy, or dd.mm.yy
  	     */
  	    tlen = strlen(sc_token);
  	    mon = atol(sc_token);
  	    token();
  
  	    if (sc_tokid == SLASH || sc_tokid == DOT) {
  		int sep;
  
  		sep = sc_tokid;
  		expect(NUMBER);
  		mday = atol(sc_token);
  		if (token() == sep) {
  		    expect(NUMBER);
  		    year = atol(sc_token);
  		    token();
  		}
  
  		/* flip months and days for European timing
  		 */
  		if (sep == DOT) {
  		    int x = mday;
  		    mday = mon;
  		    mon = x;
  		}
  	    }
  	    else if (tlen == 6 || tlen == 8) {
  		if (tlen == 8) {
  		    year = (mon % 10000) - 1900;
  		    mon /= 10000;
  		}
  		else {
  		    year = mon % 100;
  		    mon /= 100;
  		}
  		mday = mon % 100;
  		mon /= 100;
  	    }
  	    else
  		panic("garbled time");
  
  	    mon--;
  	    if (mon < 0 || mon > 11 || mday < 1 || mday > 31)
  		panic("garbled time");
  
  	    assign_date(tm, mday, mon, year);
  	    break;
      } /* case */
  } /* month */
  
  
  /* Global functions */
  
  time_t
  parsetime(int argc, char **argv)
  {
  /* Do the argument parsing, die if necessary, and return the time the job
   * should be run.
   */
      time_t nowtimer, runtimer;
      struct tm nowtime, runtime;
      int hr = 0;
      /* this MUST be initialized to zero for midnight/noon/teatime */
  
      nowtimer = time(NULL);
      nowtime = *localtime(&nowtimer);
  
      runtime = nowtime;
      runtime.tm_sec = 0;
      runtime.tm_isdst = 0;
  
      if (argc <= optind)
  	usage();
  
      init_scanner(argc-optind, argv+optind);
  
      switch (token()) {
      case NOW:	
  	    if (scc < 1) {
  		return nowtimer;
  	    }
  	    /* now is optional prefix for PLUS tree */
  	    expect(PLUS);
      case PLUS:
  	    plus(&runtime);
  	    break;
  
  	    /* MINUS is different from PLUS in that NOW is not
  	     * an optional prefix for it
  	     */
      case MINUS:
  	    minus(&runtime);
  	    break;
      case NUMBER:
  	    tod(&runtime);
  	    month(&runtime);
  	    break;
  
  	    /* evil coding for TEATIME|NOON|MIDNIGHT - we've initialised
  	     * hr to zero up above, then fall into this case in such a
  	     * way so we add +12 +4 hours to it for teatime, +12 hours
  	     * to it for noon, and nothing at all for midnight, then
  	     * set our runtime to that hour before leaping into the
  	     * month scanner
  	     */
      case TEATIME:
  	    hr += 4;
      case NOON:
  	    hr += 12;
      case MIDNIGHT:
  	    if (runtime.tm_hour >= hr) {
  		runtime.tm_mday++;
  		runtime.tm_wday++;
  	    }
  	    runtime.tm_hour = hr;
  	    runtime.tm_min = 0;
  	    token();
  	    /* FALLTHROUGH to month setting */
      default:
  	    month(&runtime);
  	    break;
      } /* ugly case statement */
      expect(EOF);
  
      /* convert back to time_t
       */
      runtime.tm_isdst = -1;
      runtimer = mktime(&runtime);
  
      if (runtimer < 0)
  	panic("garbled time");
  
      if (nowtimer > runtimer)
  	panic("trying to travel back in time");
  
      return runtimer;
  } /* parsetime */
  