cosmopolitan/libc/time/strftime.c

395 lines
13 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright (c) 1989 The Regents of the University of California. │
│ All rights reserved. │
│ │
│ Redistribution and use in source and binary forms are permitted │
│ provided that the above copyright notice and this paragraph are │
│ duplicated in all such forms and that any documentation, │
│ advertising materials, and other materials related to such │
│ distribution and use acknowledge that the software was developed │
│ by the University of California, Berkeley. The name of the │
│ University may not be used to endorse or promote products derived │
│ from this software without specific prior written permission. │
│ THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR │
│ IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/fmt/fmt.h"
#include "libc/macros.h"
#include "libc/nexgen32e/nexgen32e.h"
#include "libc/time/struct/tm.h"
#include "libc/time/time.h"
#include "libc/time/tzfile.internal.h"
STATIC_YOINK("ntoa");
asm(".ident\t\"\\n\\n\
strftime (BSD-3)\\n\
Copyright 1989 The Regents of the University of California\"");
asm(".include \"libc/disclaimer.inc\"");
static char *strftime_add(char *p, const char *pe, const char *str) {
while (p < pe && (*p = *str++) != '\0') ++p;
return p;
}
static char *strftime_conv(char *p, const char *pe, int n, const char *format) {
char buf[INT_STRLEN_MAXIMUM(int) + 1];
(snprintf)(buf, sizeof(buf), format, n);
return strftime_add(p, pe, buf);
}
static char *strftime_secs(char *p, const char *pe, const struct tm *t) {
static char buf[INT_STRLEN_MAXIMUM(int) + 1];
struct tm tmp;
int64_t s;
tmp = *t; /* Make a copy, mktime(3) modifies the tm struct. */
s = mktime(&tmp);
(snprintf)(buf, sizeof(buf), "%ld", s);
return strftime_add(p, pe, buf);
}
static char *strftime_timefmt(char *p, const char *pe, const char *format,
const struct tm *t) {
int i;
long diff;
char const *sign;
/* size_t z1, z2, z3; */
for (; *format; ++format) {
if (*format == '%') {
label:
switch (*++format) {
case '\0':
--format;
break;
case 'A':
p = strftime_add(p, pe,
(t->tm_wday < 0 || t->tm_wday > 6)
? "?"
: kWeekdayName[t->tm_wday]);
continue;
case 'a':
p = strftime_add(p, pe,
(t->tm_wday < 0 || t->tm_wday > 6)
? "?"
: kWeekdayNameShort[t->tm_wday]);
continue;
case 'B':
p = strftime_add(
p, pe,
(t->tm_mon < 0 || t->tm_mon > 11) ? "?" : kMonthName[t->tm_mon]);
continue;
case 'b':
case 'h':
p = strftime_add(p, pe,
(t->tm_mon < 0 || t->tm_mon > 11)
? "?"
: kMonthNameShort[t->tm_mon]);
continue;
case 'c':
p = strftime_timefmt(p, pe, "%D %X", t);
continue;
case 'C':
/*
** %C used to do a...
** strftime_timefmt("%a %b %e %X %Y", t);
** ...whereas now POSIX 1003.2 calls for
** something completely different.
** (ado, 5/24/93)
*/
p = strftime_conv(p, pe, div100int64(t->tm_year + TM_YEAR_BASE),
"%02d");
continue;
case 'D':
p = strftime_timefmt(p, pe, "%m/%d/%y", t);
continue;
case 'x':
/*
** Version 3.0 of strftime from Arnold Robbins
** (arnold@skeeve.atl.ga.us) does the
** equivalent of...
** strftime_timefmt("%a %b %e %Y");
** ...for %x; since the X3J11 C language
** standard calls for "date, using locale's
** date format," anything goes. Using just
** numbers (as here) makes Quakers happier.
** Word from Paul Eggert (eggert@twinsun.com)
** is that %Y-%m-%d is the ISO standard date
** format, specified in ISO 2014 and later
** ISO 8601:1988, with a summary available in
** pub/doc/ISO/english/ISO8601.ps.Z on
** ftp.uni-erlangen.de.
** (ado, 5/30/93)
*/
p = strftime_timefmt(p, pe, "%m/%d/%y", t);
continue;
case 'd':
p = strftime_conv(p, pe, t->tm_mday, "%02d");
continue;
case 'E':
case 'O':
/*
** POSIX locale extensions, a la
** Arnold Robbins' strftime version 3.0.
** The sequences
** %Ec %EC %Ex %Ey %EY
** %Od %oe %OH %OI %Om %OM
** %OS %Ou %OU %OV %Ow %OW %Oy
** are supposed to provide alternate
** representations.
** (ado, 5/24/93)
*/
goto label;
case 'e':
p = strftime_conv(p, pe, t->tm_mday, "%2d");
continue;
case 'H':
p = strftime_conv(p, pe, t->tm_hour, "%02d");
continue;
case 'I':
p = strftime_conv(p, pe, (t->tm_hour % 12) ? (t->tm_hour % 12) : 12,
"%02d");
continue;
case 'j':
p = strftime_conv(p, pe, t->tm_yday + 1, "%03d");
continue;
case 'k':
/*
** This used to be...
** strftime_conv(t->tm_hour % 12 ?
** t->tm_hour % 12 : 12, 2, ' ');
** ...and has been changed to the below to
** match SunOS 4.1.1 and Arnold Robbins'
** strftime version 3.0. That is, "%k" and
** "%l" have been swapped.
** (ado, 5/24/93)
*/
p = strftime_conv(p, pe, t->tm_hour, "%2d");
continue;
#ifdef KITCHEN_SINK
case 'K':
/*
** After all this time, still unclaimed!
*/
p = strftime_add(p, pe, "kitchen sink");
continue;
#endif /* defined KITCHEN_SINK */
case 'l':
/*
** This used to be...
** strftime_conv(t->tm_hour, 2, ' ');
** ...and has been changed to the below to
** match SunOS 4.1.1 and Arnold Robbin's
** strftime version 3.0. That is, "%k" and
** "%l" have been swapped.
** (ado, 5/24/93)
*/
p = strftime_conv(p, pe, (t->tm_hour % 12) ? (t->tm_hour % 12) : 12,
"%2d");
continue;
case 'M':
p = strftime_conv(p, pe, t->tm_min, "%02d");
continue;
case 'm':
p = strftime_conv(p, pe, t->tm_mon + 1, "%02d");
continue;
case 'n':
p = strftime_add(p, pe, "\n");
continue;
case 'p':
p = strftime_add(p, pe, t->tm_hour >= 12 ? "PM" : "AM");
continue;
case 'R':
p = strftime_timefmt(p, pe, "%H:%M", t);
continue;
case 'r':
p = strftime_timefmt(p, pe, "%I:%M:%S %p", t);
continue;
case 'S':
p = strftime_conv(p, pe, t->tm_sec, "%02d");
continue;
case 's':
p = strftime_secs(p, pe, t);
continue;
case 'T':
case 'X':
p = strftime_timefmt(p, pe, "%H:%M:%S", t);
continue;
case 't':
p = strftime_add(p, pe, "\t");
continue;
case 'U':
p = strftime_conv(p, pe, (t->tm_yday + 7 - t->tm_wday) / 7, "%02d");
continue;
case 'u':
/*
** From Arnold Robbins' strftime version 3.0:
** "ISO 8601: Weekday as a decimal number
** [1 (Monday) - 7]"
** (ado, 5/24/93)
*/
p = strftime_conv(p, pe, (t->tm_wday == 0) ? 7 : t->tm_wday, "%d");
continue;
case 'V':
/*
** From Arnold Robbins' strftime version 3.0:
** "the week number of the year (the first
** Monday as the first day of week 1) as a
** decimal number (01-53). The method for
** determining the week number is as specified
** by ISO 8601 (to wit: if the week containing
** January 1 has four or more days in the new
** year, then it is week 1, otherwise it is
** week 53 of the previous year and the next
** week is week 1)."
** (ado, 5/24/93)
*/
/*
** XXX--If January 1 falls on a Friday,
** January 1-3 are part of week 53 of the
** previous year. By analogy, if January
** 1 falls on a Thursday, are December 29-31
** of the PREVIOUS year part of week 1???
** (ado 5/24/93)
**
** You are understood not to expect this.
*/
i = (t->tm_yday + 10 - (t->tm_wday ? (t->tm_wday - 1) : 6)) / 7;
if (i == 0) {
/*
** What day of the week does
** January 1 fall on?
*/
i = t->tm_wday - (t->tm_yday - 1);
/*
** Fri Jan 1: 53
** Sun Jan 1: 52
** Sat Jan 1: 53 if previous
** year a leap
** year, else 52
*/
if (i == TM_FRIDAY)
i = 53;
else if (i == TM_SUNDAY)
i = 52;
else
i = isleap(t->tm_year + TM_YEAR_BASE) ? 53 : 52;
#ifdef XPG4_1994_04_09
/*
** As of 4/9/94, though,
** XPG4 calls for 53
** unconditionally.
*/
i = 53;
#endif /* defined XPG4_1994_04_09 */
}
p = strftime_conv(p, pe, i, "%02d");
continue;
case 'v':
/*
** From Arnold Robbins' strftime version 3.0:
** "date as dd-bbb-YYYY"
** (ado, 5/24/93)
*/
p = strftime_timefmt(p, pe, "%e-%b-%Y", t);
continue;
case 'W':
p = strftime_conv(
p, pe, (t->tm_yday + 7 - (t->tm_wday ? (t->tm_wday - 1) : 6)) / 7,
"%02d");
continue;
case 'w':
p = strftime_conv(p, pe, t->tm_wday, "%d");
continue;
case 'y':
p = strftime_conv(p, pe, (t->tm_year + TM_YEAR_BASE) % 100, "%02d");
continue;
case 'Y':
p = strftime_conv(p, pe, t->tm_year + TM_YEAR_BASE, "%04d");
continue;
case 'Z':
if (t->tm_zone) {
p = strftime_add(p, pe, t->tm_zone);
} else {
if (t->tm_isdst == 0 || t->tm_isdst == 1) {
p = strftime_add(p, pe, tzname[t->tm_isdst]);
} else {
p = strftime_add(p, pe, "?");
}
}
continue;
case 'z':
if (t->tm_isdst < 0) continue;
#ifdef TM_GMTOFF
diff = t->TM_GMTOFF;
#else /* !defined TM_GMTOFF */
if (t->tm_isdst == 0)
#ifdef USG_COMPAT
diff = -timezone;
#else /* !defined USG_COMPAT */
continue;
#endif /* !defined USG_COMPAT */
else
#ifdef ALTZONE
diff = -altzone;
#else /* !defined ALTZONE */
continue;
#endif /* !defined ALTZONE */
#endif /* !defined TM_GMTOFF */
if (diff < 0) {
sign = "-";
diff = -diff;
} else {
sign = "+";
}
p = strftime_add(p, pe, sign);
diff /= SECSPERMIN;
diff = (diff / MINSPERHOUR) * 100 + (diff % MINSPERHOUR);
p = strftime_conv(p, pe, diff, "%04d");
continue;
case '%':
/*
* X311J/88-090 (4.12.3.5): if conversion char is
* undefined, behavior is undefined. Print out the
* character itself as printf(3) also does.
*/
default:
break;
}
}
if (p >= pe) break;
*p++ = *format;
}
return p;
}
/**
* Converts time to string, e.g.
*
* char b[64];
* int64_t sec;
* struct tm tm;
* time(&sec);
* localtime_r(&sec, &tm);
* strftime(b, sizeof(b), "%Y-%m-%dT%H:%M:%S%z", &tm); // ISO8601
* strftime(b, sizeof(b), "%a, %d %b %Y %H:%M:%S %Z", &tm); // RFC1123
*
* @return bytes copied excluding nul, or 0 on error
*/
size_t strftime(char *s, size_t size, const char *f, const struct tm *t) {
char *p;
assert(t);
p = strftime_timefmt(s, s + size, f, t);
if (p < s + size) {
*p = '\0';
return p - s;
} else {
s[size - 1] = '\0';
return 0;
}
}