parsetime.c revision 941 
1/*
2 * parsetime.c - parse time for at(1)
3 * Copyright (C) 1993  Thomas Koenig
4 *
5 * modifications for english-language times
6 * Copyright (C) 1993  David Parsons
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. The name of the author(s) may not be used to endorse or promote
15 *    products derived from this software without specific prior written
16 *    permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 *  at [NOW] PLUS NUMBER MINUTES|HOURS|DAYS|WEEKS
30 *     /NUMBER [DOT NUMBER] [AM|PM]\ /[MONTH NUMBER [NUMBER]]             \
31 *     |NOON                       | |[TOMORROW]                          |
32 *     |MIDNIGHT                   | |NUMBER [SLASH NUMBER [SLASH NUMBER]]|
33 *     \TEATIME                    / \PLUS NUMBER MINUTES|HOURS|DAYS|WEEKS/
34 */
35
36/* System Headers */
37
38#include <sys/types.h>
39#include <errno.h>
40#include <stdio.h>
41#include <stdlib.h>
42#include <string.h>
43#include <time.h>
44#include <unistd.h>
45#include <ctype.h>
46
47/* Local headers */
48
49#include "at.h"
50#include "panic.h"
51
52
53/* Structures and unions */
54
55enum {	/* symbols */
56    MIDNIGHT, NOON, TEATIME,
57    PM, AM, TOMORROW, TODAY, NOW,
58    MINUTES, HOURS, DAYS, WEEKS,
59    NUMBER, PLUS, DOT, SLASH, ID, JUNK,
60    JAN, FEB, MAR, APR, MAY, JUN,
61    JUL, AUG, SEP, OCT, NOV, DEC
62};
63
64/*
65 * parse translation table - table driven parsers can be your FRIEND!
66 */
67struct {
68    char *name;	/* token name */
69    int value;	/* token id */
70} Specials[] = {
71    { "midnight", MIDNIGHT },	/* 00:00:00 of today or tomorrow */
72    { "noon", NOON },		/* 12:00:00 of today or tomorrow */
73    { "teatime", TEATIME },	/* 16:00:00 of today or tomorrow */
74    { "am", AM },		/* morning times for 0-12 clock */
75    { "pm", PM },		/* evening times for 0-12 clock */
76    { "tomorrow", TOMORROW },	/* execute 24 hours from time */
77    { "today", TODAY },		/* execute today - don't advance time */
78    { "now", NOW },		/* opt prefix for PLUS */
79
80    { "minute", MINUTES },	/* minutes multiplier */
81    { "min", MINUTES },
82    { "m", MINUTES },
83    { "minutes", MINUTES },	/* (pluralized) */
84    { "hour", HOURS },		/* hours ... */
85    { "hr", HOURS },		/* abbreviated */
86    { "h", HOURS },
87    { "hours", HOURS },		/* (pluralized) */
88    { "day", DAYS },		/* days ... */
89    { "d", DAYS },
90    { "days", DAYS },		/* (pluralized) */
91    { "week", WEEKS },		/* week ... */
92    { "w", WEEKS },
93    { "weeks", WEEKS },		/* (pluralized) */
94    { "jan", JAN },
95    { "feb", FEB },
96    { "mar", MAR },
97    { "apr", APR },
98    { "may", MAY },
99    { "jun", JUN },
100    { "jul", JUL },
101    { "aug", AUG },
102    { "sep", SEP },
103    { "oct", OCT },
104    { "nov", NOV },
105    { "dec", DEC }
106} ;
107
108/* File scope variables */
109
110static char **scp;	/* scanner - pointer at arglist */
111static char scc;	/* scanner - count of remaining arguments */
112static char *sct;	/* scanner - next char pointer in current argument */
113static int need;	/* scanner - need to advance to next argument */
114
115static char *sc_token;	/* scanner - token buffer */
116static size_t sc_len;   /* scanner - lenght of token buffer */
117static int sc_tokid;	/* scanner - token id */
118
119static char rcsid[] = "$Id: parsetime.c,v 1.1 1993/12/05 11:37:05 cgd Exp $";
120
121/* Local functions */
122
123/*
124 * parse a token, checking if it's something special to us
125 */
126static int
127parse_token(arg)
128	char *arg;
129{
130    int i;
131
132    for (i=0; i<(sizeof Specials/sizeof Specials[0]); i++)
133	if (strcasecmp(Specials[i].name, arg) == 0) {
134	    return sc_tokid = Specials[i].value;
135	}
136
137    /* not special - must be some random id */
138    return ID;
139} /* parse_token */
140
141
142/*
143 * init_scanner() sets up the scanner to eat arguments
144 */
145static void
146init_scanner(argc, argv)
147	int argc;
148	char **argv;
149{
150    scp = argv;
151    scc = argc;
152    need = 1;
153    sc_len = 1;
154    while (--argc > 0)
155	sc_len += strlen(*++argv);
156
157    sc_token = (char *) malloc(sc_len);
158    if (sc_token == NULL)
159	panic("Insufficient virtual memory");
160} /* init_scanner */
161
162/*
163 * token() fetches a token from the input stream
164 */
165static int
166token()
167{
168    int idx;
169
170    while (1) {
171	memset(sc_token, 0, sc_len);
172	sc_tokid = EOF;
173	idx = 0;
174
175	/*
176	 * if we need to read another argument, walk along the argument list;
177	 * when we fall off the arglist, we'll just return EOF forever
178	 */
179	if (need) {
180	    if (scc < 1)
181		return sc_tokid;
182	    sct = *scp;
183	    scp++;
184	    scc--;
185	    need = 0;
186	}
187	/*
188	 * eat whitespace now - if we walk off the end of the argument,
189	 * we'll continue, which puts us up at the top of the while loop
190	 * to fetch the next argument in
191	 */
192	while (isspace(*sct))
193	    ++sct;
194	if (!*sct) {
195	    need = 1;
196	    continue;
197	}
198
199	/*
200	 * preserve the first character of the new token
201	 */
202	sc_token[0] = *sct++;
203
204	/*
205	 * then see what it is
206	 */
207	if (isdigit(sc_token[0])) {
208	    while (isdigit(*sct))
209		sc_token[++idx] = *sct++;
210	    sc_token[++idx] = 0;
211	    return sc_tokid = NUMBER;
212	} else if (isalpha(sc_token[0])) {
213	    while (isalpha(*sct))
214		sc_token[++idx] = *sct++;
215	    sc_token[++idx] = 0;
216	    return parse_token(sc_token);
217	}
218	else if (sc_token[0] == ':' || sc_token[0] == '.')
219	    return sc_tokid = DOT;
220	else if (sc_token[0] == '+')
221	    return sc_tokid = PLUS;
222	else if (*sct == '/')
223	    return sc_tokid = SLASH;
224	else
225	    return sc_tokid = JUNK;
226    } /* while (1) */
227} /* token */
228
229
230/*
231 * plonk() gives an appropriate error message if a token is incorrect
232 */
233static void
234plonk(tok)
235	int tok;
236{
237    panic((tok == EOF) ? "incomplete time"
238		       : "garbled time");
239} /* plonk */
240
241
242/*
243 * expect() gets a token and dies most horribly if it's not the token we want
244 */
245static void
246expect(desired)
247	int desired;
248{
249    if (token() != desired)
250	plonk(sc_tokid);	/* and we die here... */
251} /* expect */
252
253
254/*
255 * dateadd() adds a number of minutes to a date.  It is extraordinarily
256 * stupid regarding day-of-month overflow, and will most likely not
257 * work properly
258 */
259static void
260dateadd(minutes, tm)
261	int minutes;
262	struct tm *tm;
263{
264    /* increment days */
265
266    while (minutes > 24*60) {
267	minutes -= 24*60;
268	tm->tm_mday++;
269    }
270
271    /* increment hours */
272    while (minutes > 60) {
273	minutes -= 60;
274	tm->tm_hour++;
275	if (tm->tm_hour > 23) {
276	    tm->tm_mday++;
277	    tm->tm_hour = 0;
278	}
279    }
280
281    /* increment minutes */
282    tm->tm_min += minutes;
283
284    if (tm->tm_min > 59) {
285	tm->tm_hour++;
286	tm->tm_min -= 60;
287
288	if (tm->tm_hour > 23) {
289	    tm->tm_mday++;
290	    tm->tm_hour = 0;
291	}
292    }
293} /* dateadd */
294
295
296/*
297 * plus() parses a now + time
298 *
299 *  at [NOW] PLUS NUMBER [MINUTES|HOURS|DAYS|WEEKS]
300 *
301 */
302static void
303plus(tm)
304	struct tm *tm;
305{
306    int delay;
307
308    expect(NUMBER);
309
310    delay = atoi(sc_token);
311
312    switch (token()) {
313    case WEEKS:
314	    delay *= 7;
315    case DAYS:
316	    delay *= 24;
317    case HOURS:
318	    delay *= 60;
319    case MINUTES:
320	    dateadd(delay, tm);
321	    return;
322    }
323    plonk(sc_tokid);
324} /* plus */
325
326
327/*
328 * tod() computes the time of day
329 *     [NUMBER [DOT NUMBER] [AM|PM]]
330 */
331static void
332tod(tm)
333	struct tm *tm;
334{
335    int hour, minute = 0;
336    int tlen;
337
338    hour = atoi(sc_token);
339    tlen = strlen(sc_token);
340
341    /*
342     * first pick out the time of day - if it's 4 digits, we assume
343     * a HHMM time, otherwise it's HH DOT MM time
344     */
345    if (token() == DOT) {
346	expect(NUMBER);
347	minute = atoi(sc_token);
348	if (minute > 59)
349	    panic("garbled time");
350	token();
351    } else if (tlen == 4) {
352	minute = hour%100;
353	if (minute > 59)
354	    panic("garbeld time");
355	hour = hour/100;
356    }
357
358    /*
359     * check if an AM or PM specifier was given
360     */
361    if (sc_tokid == AM || sc_tokid == PM) {
362	if (hour > 12)
363	    panic("garbled time");
364
365	if (sc_tokid == PM)
366	    hour += 12;
367	token();
368    } else if (hour > 23)
369	panic("garbled time");
370
371    /*
372     * if we specify an absolute time, we don't want to bump the day even
373     * if we've gone past that time - but if we're specifying a time plus
374     * a relative offset, it's okay to bump things
375     */
376    if ((sc_tokid == EOF || sc_tokid == PLUS) && tm->tm_hour > hour)
377	tm->tm_mday++;
378
379    tm->tm_hour = hour;
380    tm->tm_min = minute;
381    if (tm->tm_hour == 24) {
382	tm->tm_hour = 0;
383	tm->tm_mday++;
384    }
385} /* tod */
386
387
388/*
389 * assign_date() assigns a date, wrapping to next year if needed
390 */
391static void
392assign_date(tm, mday, mon, year)
393	struct tm *tm;
394	long mday, mon, year;
395{
396    if (year > 99) {
397	if (year > 1899)
398	    year -= 1900;
399	else
400	    panic("garbled time");
401    }
402
403    if (year < 0 &&
404	(tm->tm_mon > mon ||(tm->tm_mon == mon && tm->tm_mday > mday)))
405	year = tm->tm_year + 1;
406
407    tm->tm_mday = mday;
408    tm->tm_mon = mon;
409
410    if (year >= 0)
411	tm->tm_year = year;
412} /* assign_date */
413
414
415/*
416 * month() picks apart a month specification
417 *
418 *  /[<month> NUMBER [NUMBER]]           \
419 *  |[TOMORROW]                          |
420 *  |NUMBER [SLASH NUMBER [SLASH NUMBER]]|
421 *  \PLUS NUMBER MINUTES|HOURS|DAYS|WEEKS/
422 */
423static void
424month(tm)
425	struct tm *tm;
426{
427    long year= (-1);
428    long mday, mon;
429    int tlen;
430
431    switch (sc_tokid) {
432    case PLUS:
433	    plus(tm);
434	    break;
435
436    case TOMORROW:
437	    /* do something tomorrow */
438	    tm->tm_mday ++;
439    case TODAY:	/* force ourselves to stay in today - no further processing */
440	    token();
441	    break;
442
443    case JAN: case FEB: case MAR: case APR: case MAY: case JUN:
444    case JUL: case AUG: case SEP: case OCT: case NOV: case DEC:
445	    /*
446	     * do month mday [year]
447	     */
448	    mon = (sc_tokid-JAN);
449	    expect(NUMBER);
450	    mday = atol(sc_token)-1;
451	    if (token() == NUMBER) {
452		year = atol(sc_token);
453		token();
454	    }
455	    assign_date(tm, mday, mon, year);
456	    break;
457
458    case NUMBER:
459	    /*
460	     * get numeric MMDDYY, mm/dd/yy, or dd.mm.yy
461	     */
462	    tlen = strlen(sc_token);
463	    mon = atol(sc_token);
464	    token();
465
466	    if (sc_tokid == SLASH || sc_tokid == DOT) {
467		int sep;
468
469		sep = sc_tokid;
470		expect(NUMBER);
471		mday = atol(sc_token);
472		if (token() == sep) {
473		    expect(NUMBER);
474		    year = atol(sc_token);
475		    token();
476		}
477
478		/*
479		 * flip months and days for european timing
480		 */
481		if (sep == DOT) {
482		    int x = mday;
483		    mday = mon;
484		    mon = x;
485		}
486	    } else if (tlen == 6 || tlen == 8) {
487		if (tlen == 8) {
488		    year = (mon % 10000) - 1900;
489		    mon /= 10000;
490		} else {
491		    year = mon % 100;
492		    mon /= 100;
493		}
494		mday = mon % 100;
495		mon /= 100;
496	    } else
497		panic("garbled time");
498
499	    mon--;
500	    if (mon < 0 || mon > 11 || mday < 1 || mday > 31)
501		panic("garbled time");
502
503	    assign_date(tm, mday, mon, year);
504	    break;
505    } /* case */
506} /* month */
507
508
509/* Global functions */
510
511time_t
512parsetime(argc, argv)
513	int argc;
514	char **argv;
515{
516/*
517 * Do the argument parsing, die if necessary, and return the time the job
518 * should be run.
519 */
520    time_t nowtimer, runtimer;
521    struct tm nowtime, runtime;
522    int hr = 0;
523    /* this MUST be initialized to zero for midnight/noon/teatime */
524
525    nowtimer = time(NULL);
526    nowtime = *localtime(&nowtimer);
527
528    runtime = nowtime;
529    runtime.tm_sec = 0;
530    runtime.tm_isdst = 0;
531
532    if (argc <= optind)
533	usage();
534
535    init_scanner(argc-optind, argv+optind);
536
537    switch (token()) {
538    case NOW:	/* now is optional prefix for PLUS tree */
539	    expect(PLUS);
540    case PLUS:
541	    plus(&runtime);
542	    break;
543
544    case NUMBER:
545	    tod(&runtime);
546	    month(&runtime);
547	    break;
548
549	    /*
550	     * evil coding for TEATIME|NOON|MIDNIGHT - we've initialised
551	     * hr to zero up above, then fall into this case in such a
552	     * way so we add +12 +4 hours to it for teatime, +12 hours
553	     * to it for noon, and nothing at all for midnight, then
554	     * set our runtime to that hour before leaping into the
555	     * month scanner
556	     */
557    case TEATIME:
558	    hr += 4;
559    case NOON:
560	    hr += 12;
561    case MIDNIGHT:
562	    if (runtime.tm_hour >= hr)
563		runtime.tm_mday++;
564	    runtime.tm_hour = hr;
565	    runtime.tm_min = 0;
566	    token();
567	    /* fall through to month setting */
568    default:
569	    month(&runtime);
570	    break;
571    } /* ugly case statement */
572    expect(EOF);
573
574    /*
575     * adjust for daylight savings time
576     */
577    runtime.tm_isdst = -1;
578    runtimer = mktime(&runtime);
579    if (runtime.tm_isdst > 0) {
580	runtimer -= 3600;
581	runtimer = mktime(&runtime);
582    }
583
584    if (runtimer < 0)
585	panic("garbled time");
586
587    if (nowtimer > runtimer)
588	panic("Trying to travel back in time");
589
590    return runtimer;
591} /* parsetime */
592