PostgreSQL Source Code  git master
strftime.c
Go to the documentation of this file.
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 
48 struct 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 
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  "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 
109 enum warn
110 {
112 };
113 
114 static char *_add(const char *, char *, const char *);
115 static char *_conv(int, const char *, char *, const char *);
116 static char *_fmt(const char *, const struct pg_tm *, char *, const char *,
117  enum warn *);
118 static char *_yconv(int, int, bool, bool, char *, char const *);
119 
120 
121 size_t
122 pg_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 
134 static 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 
499 static 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 
508 static 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 
524 static 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 }
static char * _fmt(const char *, const struct pg_tm *, char *, const char *, enum warn *)
Definition: strftime.c:135
const char * am
Definition: strftime.c:57
const char * date_fmt
Definition: strftime.c:59
#define SECSPERMIN
Definition: private.h:101
int tm_wday
Definition: pgtime.h:33
int tm_isdst
Definition: pgtime.h:35
#define INT_STRLEN_MAXIMUM(type)
Definition: private.h:85
int tm_hour
Definition: pgtime.h:29
const char * x_fmt
Definition: strftime.c:55
const char * pm
Definition: strftime.c:58
#define MONSPERYEAR
Definition: private.h:109
#define HOURSPERDAY
Definition: private.h:103
#define DAYSPERNYEAR
Definition: private.h:105
long int tm_gmtoff
Definition: pgtime.h:36
Definition: pgtime.h:25
const char * X_fmt
Definition: strftime.c:54
#define DAYSPERLYEAR
Definition: private.h:106
#define sprintf
Definition: port.h:194
#define TM_YEAR_BASE
Definition: private.h:132
#define DAYSPERWEEK
Definition: private.h:104
char sign
Definition: informix.c:668
const char * wday[DAYSPERWEEK]
Definition: strftime.c:52
int tm_mday
Definition: pgtime.h:30
static char * buf
Definition: pg_test_fsync.c:67
int tm_mon
Definition: pgtime.h:31
const char * mon[MONSPERYEAR]
Definition: strftime.c:50
const char * tm_zone
Definition: pgtime.h:37
#define DIVISOR
static char * _yconv(int, int, bool, bool, char *, char const *)
Definition: strftime.c:525
static char * label
static char * _add(const char *, char *, const char *)
Definition: strftime.c:509
warn
Definition: strftime.c:109
#define isleap_sum(a, b)
Definition: private.h:151
int tm_year
Definition: pgtime.h:32
const char * month[MONSPERYEAR]
Definition: strftime.c:51
static const struct lc_time_T C_time_locale
Definition: strftime.c:64
size_t pg_strftime(char *s, size_t maxsize, const char *format, const struct pg_tm *t)
Definition: strftime.c:122
int tm_yday
Definition: pgtime.h:34
static char format
int tm_sec
Definition: pgtime.h:27
#define Locale
Definition: strftime.c:62
const char * weekday[DAYSPERWEEK]
Definition: strftime.c:53
int tm_min
Definition: pgtime.h:28
#define MINSPERHOUR
Definition: private.h:102
const char * c_fmt
Definition: strftime.c:56
static char * _conv(int, const char *, char *, const char *)
Definition: strftime.c:500