1/* Convert a broken-down timestamp to a string. */
2
3/*
4 * Copyright 1989 The Regents of the University of California.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS" AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32/*
33 * Based on the UCB version with the copyright notice appearing above.
34 *
35 * This is ANSIish only when "multibyte character == plain character".
36 *
37 * IDENTIFICATION
38 * src/timezone/strftime.c
39 */
40
41#include "postgres.h"
42
43#include <fcntl.h>
44
45#include "private.h"
46
47
48struct lc_time_T
49{
50 const char *mon[MONSPERYEAR];
51 const char *month[MONSPERYEAR];
52 const char *wday[DAYSPERWEEK];
53 const char *weekday[DAYSPERWEEK];
54 const char *X_fmt;
55 const char *x_fmt;
56 const char *c_fmt;
57 const char *am;
58 const char *pm;
59 const char *date_fmt;
60};
61
62#define Locale (&C_time_locale)
63
64static const struct lc_time_T C_time_locale = {
65 {
66 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
67 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
68 }, {
69 "January", "February", "March", "April", "May", "June",
70 "July", "August", "September", "October", "November", "December"
71 }, {
72 "Sun", "Mon", "Tue", "Wed",
73 "Thu", "Fri", "Sat"
74 }, {
75 "Sunday", "Monday", "Tuesday", "Wednesday",
76 "Thursday", "Friday", "Saturday"
77 },
78
79 /* X_fmt */
80 "%H:%M:%S",
81
82 /*
83 * x_fmt
84 *
85 * C99 and later require this format. Using just numbers (as here) makes
86 * Quakers happier; it's also compatible with SVR4.
87 */
88 "%m/%d/%y",
89
90 /*
91 * c_fmt
92 *
93 * C99 and later require this format. Previously this code used "%D %X",
94 * but we now conform to C99. Note that "%a %b %d %H:%M:%S %Y" is used by
95 * Solaris 2.3.
96 */
97 "%a %b %e %T %Y",
98
99 /* am */
100 "AM",
101
102 /* pm */
103 "PM",
104
105 /* date_fmt */
106 "%a %b %e %H:%M:%S %Z %Y"
107};
108
109enum warn
110{
111 IN_NONE, IN_SOME, IN_THIS, IN_ALL
112};
113
114static char *_add(const char *, char *, const char *);
115static char *_conv(int, const char *, char *, const char *);
116static char *_fmt(const char *, const struct pg_tm *, char *, const char *,
117 enum warn *);
118static char *_yconv(int, int, bool, bool, char *, char const *);
119
120
121size_t
122pg_strftime(char *s, size_t maxsize, const char *format, const struct pg_tm *t)
123{
124 char *p;
125 enum warn warn = IN_NONE;
126
127 p = _fmt(format, t, s, s + maxsize, &warn);
128 if (p == s + maxsize)
129 return 0;
130 *p = '\0';
131 return p - s;
132}
133
134static char *
135_fmt(const char *format, const struct pg_tm *t, char *pt,
136 const char *ptlim, enum warn *warnp)
137{
138 for (; *format; ++format)
139 {
140 if (*format == '%')
141 {
142 label:
143 switch (*++format)
144 {
145 case '\0':
146 --format;
147 break;
148 case 'A':
149 pt = _add((t->tm_wday < 0 ||
150 t->tm_wday >= DAYSPERWEEK) ?
151 "?" : Locale->weekday[t->tm_wday],
152 pt, ptlim);
153 continue;
154 case 'a':
155 pt = _add((t->tm_wday < 0 ||
156 t->tm_wday >= DAYSPERWEEK) ?
157 "?" : Locale->wday[t->tm_wday],
158 pt, ptlim);
159 continue;
160 case 'B':
161 pt = _add((t->tm_mon < 0 ||
162 t->tm_mon >= MONSPERYEAR) ?
163 "?" : Locale->month[t->tm_mon],
164 pt, ptlim);
165 continue;
166 case 'b':
167 case 'h':
168 pt = _add((t->tm_mon < 0 ||
169 t->tm_mon >= MONSPERYEAR) ?
170 "?" : Locale->mon[t->tm_mon],
171 pt, ptlim);
172 continue;
173 case 'C':
174
175 /*
176 * %C used to do a... _fmt("%a %b %e %X %Y", t);
177 * ...whereas now POSIX 1003.2 calls for something
178 * completely different. (ado, 1993-05-24)
179 */
180 pt = _yconv(t->tm_year, TM_YEAR_BASE,
181 true, false, pt, ptlim);
182 continue;
183 case 'c':
184 {
185 enum warn warn2 = IN_SOME;
186
187 pt = _fmt(Locale->c_fmt, t, pt, ptlim, &warn2);
188 if (warn2 == IN_ALL)
189 warn2 = IN_THIS;
190 if (warn2 > *warnp)
191 *warnp = warn2;
192 }
193 continue;
194 case 'D':
195 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
196 continue;
197 case 'd':
198 pt = _conv(t->tm_mday, "%02d", pt, ptlim);
199 continue;
200 case 'E':
201 case 'O':
202
203 /*
204 * Locale modifiers of C99 and later. The sequences %Ec
205 * %EC %Ex %EX %Ey %EY %Od %oe %OH %OI %Om %OM %OS %Ou %OU
206 * %OV %Ow %OW %Oy are supposed to provide alternative
207 * representations.
208 */
209 goto label;
210 case 'e':
211 pt = _conv(t->tm_mday, "%2d", pt, ptlim);
212 continue;
213 case 'F':
214 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
215 continue;
216 case 'H':
217 pt = _conv(t->tm_hour, "%02d", pt, ptlim);
218 continue;
219 case 'I':
220 pt = _conv((t->tm_hour % 12) ?
221 (t->tm_hour % 12) : 12,
222 "%02d", pt, ptlim);
223 continue;
224 case 'j':
225 pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
226 continue;
227 case 'k':
228
229 /*
230 * This used to be... _conv(t->tm_hour % 12 ? t->tm_hour %
231 * 12 : 12, 2, ' '); ...and has been changed to the below
232 * to match SunOS 4.1.1 and Arnold Robbins' strftime
233 * version 3.0. That is, "%k" and "%l" have been swapped.
234 * (ado, 1993-05-24)
235 */
236 pt = _conv(t->tm_hour, "%2d", pt, ptlim);
237 continue;
238#ifdef KITCHEN_SINK
239 case 'K':
240
241 /*
242 * After all this time, still unclaimed!
243 */
244 pt = _add("kitchen sink", pt, ptlim);
245 continue;
246#endif /* defined KITCHEN_SINK */
247 case 'l':
248
249 /*
250 * This used to be... _conv(t->tm_hour, 2, ' '); ...and
251 * has been changed to the below to match SunOS 4.1.1 and
252 * Arnold Robbin's strftime version 3.0. That is, "%k" and
253 * "%l" have been swapped. (ado, 1993-05-24)
254 */
255 pt = _conv((t->tm_hour % 12) ?
256 (t->tm_hour % 12) : 12,
257 "%2d", pt, ptlim);
258 continue;
259 case 'M':
260 pt = _conv(t->tm_min, "%02d", pt, ptlim);
261 continue;
262 case 'm':
263 pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
264 continue;
265 case 'n':
266 pt = _add("\n", pt, ptlim);
267 continue;
268 case 'p':
269 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
270 Locale->pm :
271 Locale->am,
272 pt, ptlim);
273 continue;
274 case 'R':
275 pt = _fmt("%H:%M", t, pt, ptlim, warnp);
276 continue;
277 case 'r':
278 pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
279 continue;
280 case 'S':
281 pt = _conv(t->tm_sec, "%02d", pt, ptlim);
282 continue;
283 case 'T':
284 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
285 continue;
286 case 't':
287 pt = _add("\t", pt, ptlim);
288 continue;
289 case 'U':
290 pt = _conv((t->tm_yday + DAYSPERWEEK -
291 t->tm_wday) / DAYSPERWEEK,
292 "%02d", pt, ptlim);
293 continue;
294 case 'u':
295
296 /*
297 * From Arnold Robbins' strftime version 3.0: "ISO 8601:
298 * Weekday as a decimal number [1 (Monday) - 7]" (ado,
299 * 1993-05-24)
300 */
301 pt = _conv((t->tm_wday == 0) ?
302 DAYSPERWEEK : t->tm_wday,
303 "%d", pt, ptlim);
304 continue;
305 case 'V': /* ISO 8601 week number */
306 case 'G': /* ISO 8601 year (four digits) */
307 case 'g': /* ISO 8601 year (two digits) */
308/*
309 * From Arnold Robbins' strftime version 3.0: "the week number of the
310 * year (the first Monday as the first day of week 1) as a decimal number
311 * (01-53)."
312 * (ado, 1993-05-24)
313 *
314 * From <https://www.cl.cam.ac.uk/~mgk25/iso-time.html> by Markus Kuhn:
315 * "Week 01 of a year is per definition the first week which has the
316 * Thursday in this year, which is equivalent to the week which contains
317 * the fourth day of January. In other words, the first week of a new year
318 * is the week which has the majority of its days in the new year. Week 01
319 * might also contain days from the previous year and the week before week
320 * 01 of a year is the last week (52 or 53) of the previous year even if
321 * it contains days from the new year. A week starts with Monday (day 1)
322 * and ends with Sunday (day 7). For example, the first week of the year
323 * 1997 lasts from 1996-12-30 to 1997-01-05..."
324 * (ado, 1996-01-02)
325 */
326 {
327 int year;
328 int base;
329 int yday;
330 int wday;
331 int w;
332
333 year = t->tm_year;
334 base = TM_YEAR_BASE;
335 yday = t->tm_yday;
336 wday = t->tm_wday;
337 for (;;)
338 {
339 int len;
340 int bot;
341 int top;
342
343 len = isleap_sum(year, base) ?
344 DAYSPERLYEAR :
345 DAYSPERNYEAR;
346
347 /*
348 * What yday (-3 ... 3) does the ISO year begin
349 * on?
350 */
351 bot = ((yday + 11 - wday) %
352 DAYSPERWEEK) - 3;
353
354 /*
355 * What yday does the NEXT ISO year begin on?
356 */
357 top = bot -
358 (len % DAYSPERWEEK);
359 if (top < -3)
360 top += DAYSPERWEEK;
361 top += len;
362 if (yday >= top)
363 {
364 ++base;
365 w = 1;
366 break;
367 }
368 if (yday >= bot)
369 {
370 w = 1 + ((yday - bot) /
371 DAYSPERWEEK);
372 break;
373 }
374 --base;
375 yday += isleap_sum(year, base) ?
376 DAYSPERLYEAR :
377 DAYSPERNYEAR;
378 }
379 if (*format == 'V')
380 pt = _conv(w, "%02d",
381 pt, ptlim);
382 else if (*format == 'g')
383 {
384 *warnp = IN_ALL;
385 pt = _yconv(year, base,
386 false, true,
387 pt, ptlim);
388 }
389 else
390 pt = _yconv(year, base,
391 true, true,
392 pt, ptlim);
393 }
394 continue;
395 case 'v':
396
397 /*
398 * From Arnold Robbins' strftime version 3.0: "date as
399 * dd-bbb-YYYY" (ado, 1993-05-24)
400 */
401 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
402 continue;
403 case 'W':
404 pt = _conv((t->tm_yday + DAYSPERWEEK -
405 (t->tm_wday ?
406 (t->tm_wday - 1) :
407 (DAYSPERWEEK - 1))) / DAYSPERWEEK,
408 "%02d", pt, ptlim);
409 continue;
410 case 'w':
411 pt = _conv(t->tm_wday, "%d", pt, ptlim);
412 continue;
413 case 'X':
414 pt = _fmt(Locale->X_fmt, t, pt, ptlim, warnp);
415 continue;
416 case 'x':
417 {
418 enum warn warn2 = IN_SOME;
419
420 pt = _fmt(Locale->x_fmt, t, pt, ptlim, &warn2);
421 if (warn2 == IN_ALL)
422 warn2 = IN_THIS;
423 if (warn2 > *warnp)
424 *warnp = warn2;
425 }
426 continue;
427 case 'y':
428 *warnp = IN_ALL;
429 pt = _yconv(t->tm_year, TM_YEAR_BASE,
430 false, true,
431 pt, ptlim);
432 continue;
433 case 'Y':
434 pt = _yconv(t->tm_year, TM_YEAR_BASE,
435 true, true,
436 pt, ptlim);
437 continue;
438 case 'Z':
439 if (t->tm_zone != NULL)
440 pt = _add(t->tm_zone, pt, ptlim);
441
442 /*
443 * C99 and later say that %Z must be replaced by the empty
444 * string if the time zone abbreviation is not
445 * determinable.
446 */
447 continue;
448 case 'z':
449 {
450 long diff;
451 char const *sign;
452 bool negative;
453
454 if (t->tm_isdst < 0)
455 continue;
456 diff = t->tm_gmtoff;
457 negative = diff < 0;
458 if (diff == 0)
459 {
460 if (t->tm_zone != NULL)
461 negative = t->tm_zone[0] == '-';
462 }
463 if (negative)
464 {
465 sign = "-";
466 diff = -diff;
467 }
468 else
469 sign = "+";
470 pt = _add(sign, pt, ptlim);
471 diff /= SECSPERMIN;
472 diff = (diff / MINSPERHOUR) * 100 +
473 (diff % MINSPERHOUR);
474 pt = _conv(diff, "%04d", pt, ptlim);
475 }
476 continue;
477 case '+':
478 pt = _fmt(Locale->date_fmt, t, pt, ptlim,
479 warnp);
480 continue;
481 case '%':
482
483 /*
484 * X311J/88-090 (4.12.3.5): if conversion char is
485 * undefined, behavior is undefined. Print out the
486 * character itself as printf(3) also does.
487 */
488 default:
489 break;
490 }
491 }
492 if (pt == ptlim)
493 break;
494 *pt++ = *format;
495 }
496 return pt;
497}
498
499static char *
500_conv(int n, const char *format, char *pt, const char *ptlim)
501{
502 char buf[INT_STRLEN_MAXIMUM(int) +1];
503
504 sprintf(buf, format, n);
505 return _add(buf, pt, ptlim);
506}
507
508static char *
509_add(const char *str, char *pt, const char *ptlim)
510{
511 while (pt < ptlim && (*pt = *str++) != '\0')
512 ++pt;
513 return pt;
514}
515
516/*
517 * POSIX and the C Standard are unclear or inconsistent about
518 * what %C and %y do if the year is negative or exceeds 9999.
519 * Use the convention that %C concatenated with %y yields the
520 * same output as %Y, and that %Y contains at least 4 bytes,
521 * with more only if necessary.
522 */
523
524static char *
525_yconv(int a, int b, bool convert_top, bool convert_yy,
526 char *pt, const char *ptlim)
527{
528 int lead;
529 int trail;
530
531#define DIVISOR 100
532 trail = a % DIVISOR + b % DIVISOR;
533 lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
534 trail %= DIVISOR;
535 if (trail < 0 && lead > 0)
536 {
537 trail += DIVISOR;
538 --lead;
539 }
540 else if (lead < 0 && trail > 0)
541 {
542 trail -= DIVISOR;
543 ++lead;
544 }
545 if (convert_top)
546 {
547 if (lead == 0 && trail < 0)
548 pt = _add("-0", pt, ptlim);
549 else
550 pt = _conv(lead, "%02d", pt, ptlim);
551 }
552 if (convert_yy)
553 pt = _conv(((trail < 0) ? -trail : trail), "%02d", pt, ptlim);
554 return pt;
555}
556