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1 #ifndef lint
2 #ifndef NOID
3 static char elsieid[] = "@(#)strftime.c 8.1";
4 /*
5 ** Based on the UCB version with the ID appearing below.
6 ** This is ANSIish only when "multibyte character == plain character".
7 */
8 #endif /* !defined NOID */
9 #endif /* !defined lint */
10 
11 #include "private.h"
12 
13 /*
14 ** Copyright (c) 1989 The Regents of the University of California.
15 ** All rights reserved.
16 **
17 ** Redistribution and use in source and binary forms are permitted
18 ** provided that the above copyright notice and this paragraph are
19 ** duplicated in all such forms and that any documentation,
20 ** advertising materials, and other materials related to such
21 ** distribution and use acknowledge that the software was developed
22 ** by the University of California, Berkeley. The name of the
23 ** University may not be used to endorse or promote products derived
24 ** from this software without specific prior written permission.
25 ** THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
26 ** IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
27 ** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
28 */
29 
30 #ifndef LIBC_SCCS
31 #ifndef lint
32 static const char   sccsid[] = "@(#)strftime.c  5.4 (Berkeley) 3/14/89";
33 #endif /* !defined lint */
34 #endif /* !defined LIBC_SCCS */
35 
36 #include "tzfile.h"
37 #include "fcntl.h"
38 #include "locale.h"
39 #include <ctype.h>
40 #include <time64.h>
41 
42 /* struct lc_time_T is now defined as strftime_locale
43  * in <time.h>
44  */
45 #if 1
46 #define  lc_time_T    strftime_locale
47 #else
48 struct lc_time_T {
49     const char *    mon[MONSPERYEAR];
50     const char *    month[MONSPERYEAR];
51     const char *    wday[DAYSPERWEEK];
52     const char *    weekday[DAYSPERWEEK];
53     const char *    X_fmt;
54     const char *    x_fmt;
55     const char *    c_fmt;
56     const char *    am;
57     const char *    pm;
58     const char *    date_fmt;
59 };
60 #endif
61 
62 #define Locale  (&C_time_locale)
63 
64 static 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         "January", "February", "March", "April", "May", "June",
73         "July", "August", "September", "October", "November", "December"
74     }, {
75         "Sun", "Mon", "Tue", "Wed",
76         "Thu", "Fri", "Sat"
77     }, {
78         "Sunday", "Monday", "Tuesday", "Wednesday",
79         "Thursday", "Friday", "Saturday"
80     },
81 
82     /* X_fmt */
83     "%H:%M:%S",
84 
85     /*
86     ** x_fmt
87     ** C99 requires this format.
88     ** Using just numbers (as here) makes Quakers happier;
89     ** it's also compatible with SVR4.
90     */
91     "%m/%d/%y",
92 
93     /*
94     ** c_fmt
95     ** C99 requires this format.
96     ** Previously this code used "%D %X", but we now conform to C99.
97     ** Note that
98     **  "%a %b %d %H:%M:%S %Y"
99     ** is used by Solaris 2.3.
100     */
101     "%a %b %e %T %Y",
102 
103     /* am */
104     "AM",
105 
106     /* pm */
107     "PM",
108 
109     /* date_fmt */
110     "%a %b %e %H:%M:%S %Z %Y"
111 };
112 
113 static char *   _add P((const char *, char *, const char *, int));
114 static char *   _conv P((int, const char *, char *, const char *));
115 static char *   _fmt P((const char *, const struct tm *, char *, const char *,
116             int *, const struct strftime_locale*));
117 static char *   _yconv P((int, int, int, int, char *, const char *, int));
118 static char *   getformat P((int, char *, char *, char *, char *));
119 
120 extern char *   tzname[];
121 
122 #ifndef YEAR_2000_NAME
123 #define YEAR_2000_NAME  "CHECK_STRFTIME_FORMATS_FOR_TWO_DIGIT_YEARS"
124 #endif /* !defined YEAR_2000_NAME */
125 
126 #define IN_NONE 0
127 #define IN_SOME 1
128 #define IN_THIS 2
129 #define IN_ALL  3
130 
131 #define FORCE_LOWER_CASE 0x100
132 
133 size_t
strftime(s,maxsize,format,t)134 strftime(s, maxsize, format, t)
135 char * const        s;
136 const size_t        maxsize;
137 const char * const  format;
138 const struct tm * const t;
139 {
140     return strftime_tz(s, maxsize, format, t, Locale);
141 }
142 
143 size_t
strftime_tz(s,maxsize,format,t,locale)144 strftime_tz(s, maxsize, format, t, locale)
145 char * const        s;
146 const size_t        maxsize;
147 const char * const  format;
148 const struct tm * const t;
149 const struct strftime_locale *locale;
150 {
151     char *  p;
152     int warn;
153 
154     tzset();
155     warn = IN_NONE;
156     p = _fmt(((format == NULL) ? "%c" : format), t, s, s + maxsize, &warn, locale);
157 #if 0  /* ifndef NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
158     if (warn != IN_NONE && getenv(YEAR_2000_NAME) != NULL) {
159         (void) fprintf(stderr, "\n");
160         if (format == NULL)
161             (void) fprintf(stderr, "NULL strftime format ");
162         else    (void) fprintf(stderr, "strftime format \"%s\" ",
163                 format);
164         (void) fprintf(stderr, "yields only two digits of years in ");
165         if (warn == IN_SOME)
166             (void) fprintf(stderr, "some locales");
167         else if (warn == IN_THIS)
168             (void) fprintf(stderr, "the current locale");
169         else    (void) fprintf(stderr, "all locales");
170         (void) fprintf(stderr, "\n");
171     }
172 #endif /* !defined NO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU */
173     if (p == s + maxsize)
174         return 0;
175     *p = '\0';
176     return p - s;
177 }
178 
getformat(int modifier,char * normal,char * underscore,char * dash,char * zero)179 static char *getformat(int modifier, char *normal, char *underscore,
180                        char *dash, char *zero) {
181     switch (modifier) {
182     case '_':
183         return underscore;
184 
185     case '-':
186         return dash;
187 
188     case '0':
189         return zero;
190     }
191 
192     return normal;
193 }
194 
195 static char *
_fmt(format,t,pt,ptlim,warnp,locale)196 _fmt(format, t, pt, ptlim, warnp, locale)
197 const char *        format;
198 const struct tm * const t;
199 char *          pt;
200 const char * const  ptlim;
201 int *           warnp;
202 const struct strftime_locale* locale;
203 {
204     for ( ; *format; ++format) {
205         if (*format == '%') {
206             int modifier = 0;
207 label:
208             switch (*++format) {
209             case '\0':
210                 --format;
211                 break;
212             case 'A':
213                 pt = _add((t->tm_wday < 0 ||
214                     t->tm_wday >= DAYSPERWEEK) ?
215                     "?" : locale->weekday[t->tm_wday],
216                     pt, ptlim, modifier);
217                 continue;
218             case 'a':
219                 pt = _add((t->tm_wday < 0 ||
220                     t->tm_wday >= DAYSPERWEEK) ?
221                     "?" : locale->wday[t->tm_wday],
222                     pt, ptlim, modifier);
223                 continue;
224             case 'B':
225                 if (modifier == '-') {
226                     pt = _add((t->tm_mon < 0 ||
227                                 t->tm_mon >= MONSPERYEAR) ?
228                                 "?" : locale->standalone_month[t->tm_mon],
229                                 pt, ptlim, modifier);
230                 } else {
231                     pt = _add((t->tm_mon < 0 ||
232                                 t->tm_mon >= MONSPERYEAR) ?
233                                 "?" : locale->month[t->tm_mon],
234                                 pt, ptlim, modifier);
235                 }
236                 continue;
237             case 'b':
238             case 'h':
239                 pt = _add((t->tm_mon < 0 ||
240                     t->tm_mon >= MONSPERYEAR) ?
241                     "?" : locale->mon[t->tm_mon],
242                     pt, ptlim, modifier);
243                 continue;
244             case 'C':
245                 /*
246                 ** %C used to do a...
247                 **  _fmt("%a %b %e %X %Y", t);
248                 ** ...whereas now POSIX 1003.2 calls for
249                 ** something completely different.
250                 ** (ado, 1993-05-24)
251                 */
252                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 0,
253                     pt, ptlim, modifier);
254                 continue;
255             case 'c':
256                 {
257                 int warn2 = IN_SOME;
258 
259                 pt = _fmt(locale->c_fmt, t, pt, ptlim, warnp, locale);
260                 if (warn2 == IN_ALL)
261                     warn2 = IN_THIS;
262                 if (warn2 > *warnp)
263                     *warnp = warn2;
264                 }
265                 continue;
266             case 'D':
267                                 pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp, locale);
268                 continue;
269             case 'd':
270                                 pt = _conv(t->tm_mday,
271                                            getformat(modifier, "%02d",
272                                                      "%2d", "%d", "%02d"),
273                                            pt, ptlim);
274                 continue;
275             case 'E':
276             case 'O':
277                 /*
278                 ** C99 locale modifiers.
279                 ** The sequences
280                 **  %Ec %EC %Ex %EX %Ey %EY
281                 **  %Od %oe %OH %OI %Om %OM
282                 **  %OS %Ou %OU %OV %Ow %OW %Oy
283                 ** are supposed to provide alternate
284                 ** representations.
285                 */
286                 goto label;
287             case '_':
288             case '-':
289             case '0':
290             case '^':
291             case '#':
292                 modifier = *format;
293                 goto label;
294             case 'e':
295                 pt = _conv(t->tm_mday,
296                                            getformat(modifier, "%2d",
297                                                      "%2d", "%d", "%02d"),
298                                            pt, ptlim);
299                 continue;
300             case 'F':
301                 pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp, locale);
302                 continue;
303             case 'H':
304                 pt = _conv(t->tm_hour,
305                                            getformat(modifier, "%02d",
306                                                      "%2d", "%d", "%02d"),
307                                            pt, ptlim);
308                 continue;
309             case 'I':
310                 pt = _conv((t->tm_hour % 12) ?
311                     (t->tm_hour % 12) : 12,
312                     getformat(modifier, "%02d",
313                                                   "%2d", "%d", "%02d"),
314                                         pt, ptlim);
315                 continue;
316             case 'j':
317                 pt = _conv(t->tm_yday + 1,
318                            getformat(modifier, "%03d", "%3d", "%d", "%03d"),
319                            pt, ptlim);
320                 continue;
321             case 'k':
322                 /*
323                 ** This used to be...
324                 **  _conv(t->tm_hour % 12 ?
325                 **      t->tm_hour % 12 : 12, 2, ' ');
326                 ** ...and has been changed to the below to
327                 ** match SunOS 4.1.1 and Arnold Robbins'
328                 ** strftime version 3.0. That is, "%k" and
329                 ** "%l" have been swapped.
330                 ** (ado, 1993-05-24)
331                 */
332                 pt = _conv(t->tm_hour,
333                                            getformat(modifier, "%2d",
334                                                      "%2d", "%d", "%02d"),
335                                            pt, ptlim);
336                 continue;
337 #ifdef KITCHEN_SINK
338             case 'K':
339                 /*
340                 ** After all this time, still unclaimed!
341                 */
342                 pt = _add("kitchen sink", pt, ptlim, modifier);
343                 continue;
344 #endif /* defined KITCHEN_SINK */
345             case 'l':
346                 /*
347                 ** This used to be...
348                 **  _conv(t->tm_hour, 2, ' ');
349                 ** ...and has been changed to the below to
350                 ** match SunOS 4.1.1 and Arnold Robbin's
351                 ** strftime version 3.0. That is, "%k" and
352                 ** "%l" have been swapped.
353                 ** (ado, 1993-05-24)
354                 */
355                 pt = _conv((t->tm_hour % 12) ?
356                     (t->tm_hour % 12) : 12,
357                     getformat(modifier, "%2d",
358                                                   "%2d", "%d", "%02d"),
359                                         pt, ptlim);
360                 continue;
361             case 'M':
362                 pt = _conv(t->tm_min,
363                                            getformat(modifier, "%02d",
364                                                      "%2d", "%d", "%02d"),
365                                            pt, ptlim);
366                 continue;
367             case 'm':
368                 pt = _conv(t->tm_mon + 1,
369                                            getformat(modifier, "%02d",
370                                                      "%2d", "%d", "%02d"),
371                                            pt, ptlim);
372                 continue;
373             case 'n':
374                 pt = _add("\n", pt, ptlim, modifier);
375                 continue;
376             case 'p':
377                 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
378                     locale->pm :
379                     locale->am,
380                     pt, ptlim, modifier);
381                 continue;
382             case 'P':
383                 pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
384                     locale->pm :
385                     locale->am,
386                     pt, ptlim, FORCE_LOWER_CASE);
387                 continue;
388             case 'R':
389                 pt = _fmt("%H:%M", t, pt, ptlim, warnp, locale);
390                 continue;
391             case 'r':
392                 pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp, locale);
393                 continue;
394             case 'S':
395                 pt = _conv(t->tm_sec,
396                                            getformat(modifier, "%02d",
397                                                      "%2d", "%d", "%02d"),
398                                            pt, ptlim);
399                 continue;
400             case 's':
401                 {
402                     struct tm   tm;
403                     char        buf[INT_STRLEN_MAXIMUM(
404                                 time64_t) + 1];
405                     time64_t    mkt;
406 
407                     tm = *t;
408                     mkt = mktime64(&tm);
409                     if (TYPE_SIGNED(time64_t))
410                         (void) snprintf(buf, sizeof(buf), "%lld",
411                             (long long) mkt);
412                     else    (void) snprintf(buf, sizeof(buf), "%llu",
413                             (unsigned long long) mkt);
414                     pt = _add(buf, pt, ptlim, modifier);
415                 }
416                 continue;
417             case 'T':
418                 pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp, locale);
419                 continue;
420             case 't':
421                 pt = _add("\t", pt, ptlim, modifier);
422                 continue;
423             case 'U':
424                 pt = _conv((t->tm_yday + DAYSPERWEEK -
425                     t->tm_wday) / DAYSPERWEEK,
426                     getformat(modifier, "%02d",
427                                                   "%2d", "%d", "%02d"),
428                                         pt, ptlim);
429                 continue;
430             case 'u':
431                 /*
432                 ** From Arnold Robbins' strftime version 3.0:
433                 ** "ISO 8601: Weekday as a decimal number
434                 ** [1 (Monday) - 7]"
435                 ** (ado, 1993-05-24)
436                 */
437                 pt = _conv((t->tm_wday == 0) ?
438                     DAYSPERWEEK : t->tm_wday, "%d", pt, ptlim);
439                 continue;
440             case 'V':   /* ISO 8601 week number */
441             case 'G':   /* ISO 8601 year (four digits) */
442             case 'g':   /* ISO 8601 year (two digits) */
443 /*
444 ** From Arnold Robbins' strftime version 3.0: "the week number of the
445 ** year (the first Monday as the first day of week 1) as a decimal number
446 ** (01-53)."
447 ** (ado, 1993-05-24)
448 **
449 ** From "http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html" by Markus Kuhn:
450 ** "Week 01 of a year is per definition the first week which has the
451 ** Thursday in this year, which is equivalent to the week which contains
452 ** the fourth day of January. In other words, the first week of a new year
453 ** is the week which has the majority of its days in the new year. Week 01
454 ** might also contain days from the previous year and the week before week
455 ** 01 of a year is the last week (52 or 53) of the previous year even if
456 ** it contains days from the new year. A week starts with Monday (day 1)
457 ** and ends with Sunday (day 7). For example, the first week of the year
458 ** 1997 lasts from 1996-12-30 to 1997-01-05..."
459 ** (ado, 1996-01-02)
460 */
461                 {
462                     int year;
463                     int base;
464                     int yday;
465                     int wday;
466                     int w;
467 
468                     year = t->tm_year;
469                     base = TM_YEAR_BASE;
470                     yday = t->tm_yday;
471                     wday = t->tm_wday;
472                     for ( ; ; ) {
473                         int len;
474                         int bot;
475                         int top;
476 
477                         len = isleap_sum(year, base) ?
478                             DAYSPERLYEAR :
479                             DAYSPERNYEAR;
480                         /*
481                         ** What yday (-3 ... 3) does
482                         ** the ISO year begin on?
483                         */
484                         bot = ((yday + 11 - wday) %
485                             DAYSPERWEEK) - 3;
486                         /*
487                         ** What yday does the NEXT
488                         ** ISO year begin on?
489                         */
490                         top = bot -
491                             (len % DAYSPERWEEK);
492                         if (top < -3)
493                             top += DAYSPERWEEK;
494                         top += len;
495                         if (yday >= top) {
496                             ++base;
497                             w = 1;
498                             break;
499                         }
500                         if (yday >= bot) {
501                             w = 1 + ((yday - bot) /
502                                 DAYSPERWEEK);
503                             break;
504                         }
505                         --base;
506                         yday += isleap_sum(year, base) ?
507                             DAYSPERLYEAR :
508                             DAYSPERNYEAR;
509                     }
510 #ifdef XPG4_1994_04_09
511                     if ((w == 52 &&
512                         t->tm_mon == TM_JANUARY) ||
513                         (w == 1 &&
514                         t->tm_mon == TM_DECEMBER))
515                             w = 53;
516 #endif /* defined XPG4_1994_04_09 */
517                     if (*format == 'V')
518                         pt = _conv(w,
519                                                            getformat(modifier,
520                                                                      "%02d",
521                                                                      "%2d",
522                                                                      "%d",
523                                                                      "%02d"),
524                                pt, ptlim);
525                     else if (*format == 'g') {
526                         *warnp = IN_ALL;
527                         pt = _yconv(year, base, 0, 1,
528                             pt, ptlim, modifier);
529                     } else  pt = _yconv(year, base, 1, 1,
530                             pt, ptlim, modifier);
531                 }
532                 continue;
533             case 'v':
534                 /*
535                 ** From Arnold Robbins' strftime version 3.0:
536                 ** "date as dd-bbb-YYYY"
537                 ** (ado, 1993-05-24)
538                 */
539                 pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp, locale);
540                 continue;
541             case 'W':
542                 pt = _conv((t->tm_yday + DAYSPERWEEK -
543                     (t->tm_wday ?
544                     (t->tm_wday - 1) :
545                     (DAYSPERWEEK - 1))) / DAYSPERWEEK,
546                     getformat(modifier, "%02d",
547                                                   "%2d", "%d", "%02d"),
548                                         pt, ptlim);
549                 continue;
550             case 'w':
551                 pt = _conv(t->tm_wday, "%d", pt, ptlim);
552                 continue;
553             case 'X':
554                 pt = _fmt(locale->X_fmt, t, pt, ptlim, warnp, locale);
555                 continue;
556             case 'x':
557                 {
558                 int warn2 = IN_SOME;
559 
560                 pt = _fmt(locale->x_fmt, t, pt, ptlim, &warn2, locale);
561                 if (warn2 == IN_ALL)
562                     warn2 = IN_THIS;
563                 if (warn2 > *warnp)
564                     *warnp = warn2;
565                 }
566                 continue;
567             case 'y':
568                 *warnp = IN_ALL;
569                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 0, 1,
570                     pt, ptlim, modifier);
571                 continue;
572             case 'Y':
573                 pt = _yconv(t->tm_year, TM_YEAR_BASE, 1, 1,
574                     pt, ptlim, modifier);
575                 continue;
576             case 'Z':
577 #ifdef TM_ZONE
578                 if (t->TM_ZONE != NULL)
579                     pt = _add(t->TM_ZONE, pt, ptlim,
580                                                   modifier);
581                 else
582 #endif /* defined TM_ZONE */
583                 if (t->tm_isdst >= 0)
584                     pt = _add(tzname[t->tm_isdst != 0],
585                         pt, ptlim, modifier);
586                 /*
587                 ** C99 says that %Z must be replaced by the
588                 ** empty string if the time zone is not
589                 ** determinable.
590                 */
591                 continue;
592             case 'z':
593                 {
594                 int     diff;
595                 char const *    sign;
596 
597                 if (t->tm_isdst < 0)
598                     continue;
599 #ifdef TM_GMTOFF
600                 diff = t->TM_GMTOFF;
601 #else /* !defined TM_GMTOFF */
602                 /*
603                 ** C99 says that the UTC offset must
604                 ** be computed by looking only at
605                 ** tm_isdst. This requirement is
606                 ** incorrect, since it means the code
607                 ** must rely on magic (in this case
608                 ** altzone and timezone), and the
609                 ** magic might not have the correct
610                 ** offset. Doing things correctly is
611                 ** tricky and requires disobeying C99;
612                 ** see GNU C strftime for details.
613                 ** For now, punt and conform to the
614                 ** standard, even though it's incorrect.
615                 **
616                 ** C99 says that %z must be replaced by the
617                 ** empty string if the time zone is not
618                 ** determinable, so output nothing if the
619                 ** appropriate variables are not available.
620                 */
621                 if (t->tm_isdst == 0)
622 #ifdef USG_COMPAT
623                     diff = -timezone;
624 #else /* !defined USG_COMPAT */
625                     continue;
626 #endif /* !defined USG_COMPAT */
627                 else
628 #ifdef ALTZONE
629                     diff = -altzone;
630 #else /* !defined ALTZONE */
631                     continue;
632 #endif /* !defined ALTZONE */
633 #endif /* !defined TM_GMTOFF */
634                 if (diff < 0) {
635                     sign = "-";
636                     diff = -diff;
637                 } else  sign = "+";
638                 pt = _add(sign, pt, ptlim, modifier);
639                 diff /= SECSPERMIN;
640                 diff = (diff / MINSPERHOUR) * 100 +
641                     (diff % MINSPERHOUR);
642                 pt = _conv(diff,
643                                            getformat(modifier, "%04d",
644                                                      "%4d", "%d", "%04d"),
645                                            pt, ptlim);
646                 }
647                 continue;
648             case '+':
649                 pt = _fmt(locale->date_fmt, t, pt, ptlim,
650                     warnp, locale);
651                 continue;
652             case '%':
653             /*
654             ** X311J/88-090 (4.12.3.5): if conversion char is
655             ** undefined, behavior is undefined. Print out the
656             ** character itself as printf(3) also does.
657             */
658             default:
659                 break;
660             }
661         }
662         if (pt == ptlim)
663             break;
664         *pt++ = *format;
665     }
666     return pt;
667 }
668 
669 static char *
_conv(n,format,pt,ptlim)670 _conv(n, format, pt, ptlim)
671 const int       n;
672 const char * const  format;
673 char * const        pt;
674 const char * const  ptlim;
675 {
676     char    buf[INT_STRLEN_MAXIMUM(int) + 1];
677 
678     (void) snprintf(buf, sizeof(buf), format, n);
679     return _add(buf, pt, ptlim, 0);
680 }
681 
682 static char *
_add(str,pt,ptlim,modifier)683 _add(str, pt, ptlim, modifier)
684 const char *        str;
685 char *          pt;
686 const char * const  ptlim;
687 int                     modifier;
688 {
689         int c;
690 
691         switch (modifier) {
692         case FORCE_LOWER_CASE:
693                 while (pt < ptlim && (*pt = tolower(*str++)) != '\0') {
694                         ++pt;
695                 }
696                 break;
697 
698         case '^':
699                 while (pt < ptlim && (*pt = toupper(*str++)) != '\0') {
700                         ++pt;
701                 }
702                 break;
703 
704         case '#':
705                 while (pt < ptlim && (c = *str++) != '\0') {
706                         if (isupper(c)) {
707                                 c = tolower(c);
708                         } else if (islower(c)) {
709                                 c = toupper(c);
710                         }
711                         *pt = c;
712                         ++pt;
713                 }
714 
715                 break;
716 
717         default:
718                 while (pt < ptlim && (*pt = *str++) != '\0') {
719                         ++pt;
720                 }
721         }
722 
723     return pt;
724 }
725 
726 /*
727 ** POSIX and the C Standard are unclear or inconsistent about
728 ** what %C and %y do if the year is negative or exceeds 9999.
729 ** Use the convention that %C concatenated with %y yields the
730 ** same output as %Y, and that %Y contains at least 4 bytes,
731 ** with more only if necessary.
732 */
733 
734 static char *
_yconv(a,b,convert_top,convert_yy,pt,ptlim,modifier)735 _yconv(a, b, convert_top, convert_yy, pt, ptlim, modifier)
736 const int       a;
737 const int       b;
738 const int       convert_top;
739 const int       convert_yy;
740 char *          pt;
741 const char * const  ptlim;
742 int                     modifier;
743 {
744     register int    lead;
745     register int    trail;
746 
747 #define DIVISOR 100
748     trail = a % DIVISOR + b % DIVISOR;
749     lead = a / DIVISOR + b / DIVISOR + trail / DIVISOR;
750     trail %= DIVISOR;
751     if (trail < 0 && lead > 0) {
752         trail += DIVISOR;
753         --lead;
754     } else if (lead < 0 && trail > 0) {
755         trail -= DIVISOR;
756         ++lead;
757     }
758     if (convert_top) {
759         if (lead == 0 && trail < 0)
760             pt = _add("-0", pt, ptlim, modifier);
761         else    pt = _conv(lead, getformat(modifier, "%02d",
762                                                    "%2d", "%d", "%02d"),
763                                    pt, ptlim);
764     }
765     if (convert_yy)
766         pt = _conv(((trail < 0) ? -trail : trail),
767                            getformat(modifier, "%02d", "%2d", "%d", "%02d"),
768                            pt, ptlim);
769     return pt;
770 }
771