cosmopolitan/net/http/formathttpdatetime.c
Justine Tunney b0df6c1fce
Implement proper time zone support
Cosmopolitan now supports 104 time zones. They're embedded inside any
binary that links the localtime() function. Doing so adds about 100kb
to the binary size. This change also gets time zones working properly
on Windows for the first time. It's not needed to have /etc/localtime
exist on Windows, since we can get this information from WIN32. We're
also now updated to the latest version of Paul Eggert's TZ library.
2024-05-04 23:06:37 -07:00

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/macros.internal.h"
#include "libc/str/str.h"
#include "libc/time.h"
#include "net/http/http.h"
/**
* Formats HTTP timestamp, e.g.
*
* Sun, 04 Oct 2020 19:50:10 GMT
*
* This function is the same as:
*
* strftime(p, 30, "%a, %d %b %Y %H:%M:%S %Z", tm)
*
* Except this function goes 10x faster:
*
* FormatHttpDateTime l: 25𝑐 8𝑛𝑠
* strftime l: 709𝑐 229𝑛𝑠
*
* @param tm must be zulu see gmtime_r() and nowl()
* @see ParseHttpDateTime()
*/
char *FormatHttpDateTime(char p[hasatleast 30], struct tm *tm) {
unsigned i;
p = mempcpy(p, kWeekdayNameShort[tm->tm_wday], 3);
*p++ = ',';
*p++ = ' ';
i = MIN(MAX(tm->tm_mday, 1), 31);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ' ';
i = MIN(MAX(tm->tm_mon, 0), 11);
p = mempcpy(p, kMonthNameShort[i], 3);
*p++ = ' ';
i = MIN(MAX(tm->tm_year + 1900, 0), 9999);
*p++ = '0' + i / 1000;
*p++ = '0' + i / 100 % 10;
*p++ = '0' + i / 10 % 10;
*p++ = '0' + i % 10;
*p++ = ' ';
i = MIN(MAX(tm->tm_hour, 0), 23);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ':';
i = MIN(MAX(tm->tm_min, 0), 59);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ':';
i = MIN(MAX(tm->tm_sec, 0), 59);
*p++ = '0' + i / 10;
*p++ = '0' + i % 10;
*p++ = ' ';
*p++ = 'G';
*p++ = 'M';
*p++ = 'T';
*p = '\0';
return p;
}