git/date.c
Linus Torvalds f80cd783c6 date.c: add "show_date()" function.
Kind of like ctime(), but not as broken.
2005-05-06 15:28:59 -07:00

457 lines
10 KiB
C

/*
* GIT - The information manager from hell
*
* Copyright (C) Linus Torvalds, 2005
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
static time_t my_mktime(struct tm *tm)
{
static const int mdays[] = {
0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
};
int year = tm->tm_year - 70;
int month = tm->tm_mon;
int day = tm->tm_mday;
if (year < 0 || year > 129) /* algo only works for 1970-2099 */
return -1;
if (month < 0 || month > 11) /* array bounds */
return -1;
if (month < 2 || (year + 2) % 4)
day--;
return (year * 365 + (year + 1) / 4 + mdays[month] + day) * 24*60*60UL +
tm->tm_hour * 60*60 + tm->tm_min * 60 + tm->tm_sec;
}
static const char *month_names[] = {
"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"
};
static const char *weekday_names[] = {
"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
};
/*
* The "tz" thing is passed in as this strange "decimal parse of tz"
* thing, which means that tz -0100 is passed in as the integer -100,
* even though it means "sixty minutes off"
*/
const char *show_date(unsigned long time, int tz)
{
struct tm *tm;
time_t t;
static char timebuf[200];
int minutes;
minutes = tz < 0 ? -tz : tz;
minutes = (tz / 100)*60 + (tz % 100);
minutes = tz < 0 ? -minutes : minutes;
t = time - minutes * 60;
tm = gmtime(&t);
if (!tm)
return NULL;
sprintf(timebuf, "%.3s %.3s %d %02d:%02d:%02d %d %+05d",
weekday_names[tm->tm_wday],
month_names[tm->tm_mon],
tm->tm_mday,
tm->tm_hour, tm->tm_min, tm->tm_sec,
tm->tm_year + 1900, tz);
return timebuf;
}
/*
* Check these. And note how it doesn't do the summer-time conversion.
*
* In my world, it's always summer, and things are probably a bit off
* in other ways too.
*/
static const struct {
const char *name;
int offset;
int dst;
} timezone_names[] = {
{ "IDLW", -12, 0, }, /* International Date Line West */
{ "NT", -11, 0, }, /* Nome */
{ "CAT", -10, 0, }, /* Central Alaska */
{ "HST", -10, 0, }, /* Hawaii Standard */
{ "HDT", -10, 1, }, /* Hawaii Daylight */
{ "YST", -9, 0, }, /* Yukon Standard */
{ "YDT", -9, 1, }, /* Yukon Daylight */
{ "PST", -8, 0, }, /* Pacific Standard */
{ "PDT", -8, 1, }, /* Pacific Daylight */
{ "MST", -7, 0, }, /* Mountain Standard */
{ "MDT", -7, 1, }, /* Mountain Daylight */
{ "CST", -6, 0, }, /* Central Standard */
{ "CDT", -6, 1, }, /* Central Daylight */
{ "EST", -5, 0, }, /* Eastern Standard */
{ "EDT", -5, 1, }, /* Eastern Daylight */
{ "AST", -3, 0, }, /* Atlantic Standard */
{ "ADT", -3, 1, }, /* Atlantic Daylight */
{ "WAT", -1, 0, }, /* West Africa */
{ "GMT", 0, 0, }, /* Greenwich Mean */
{ "UTC", 0, 0, }, /* Universal (Coordinated) */
{ "WET", 0, 0, }, /* Western European */
{ "BST", 0, 1, }, /* British Summer */
{ "CET", +1, 0, }, /* Central European */
{ "MET", +1, 0, }, /* Middle European */
{ "MEWT", +1, 0, }, /* Middle European Winter */
{ "MEST", +1, 1, }, /* Middle European Summer */
{ "CEST", +1, 1, }, /* Central European Summer */
{ "MESZ", +1, 1, }, /* Middle European Summer */
{ "FWT", +1, 0, }, /* French Winter */
{ "FST", +1, 1, }, /* French Summer */
{ "EET", +2, 0, }, /* Eastern Europe, USSR Zone 1 */
{ "EEST", +2, 1, }, /* Eastern European Daylight */
{ "WAST", +7, 0, }, /* West Australian Standard */
{ "WADT", +7, 1, }, /* West Australian Daylight */
{ "CCT", +8, 0, }, /* China Coast, USSR Zone 7 */
{ "JST", +9, 0, }, /* Japan Standard, USSR Zone 8 */
{ "EAST", +10, 0, }, /* Eastern Australian Standard */
{ "EADT", +10, 1, }, /* Eastern Australian Daylight */
{ "GST", +10, 0, }, /* Guam Standard, USSR Zone 9 */
{ "NZT", +11, 0, }, /* New Zealand */
{ "NZST", +11, 0, }, /* New Zealand Standard */
{ "NZDT", +11, 1, }, /* New Zealand Daylight */
{ "IDLE", +12, 0, }, /* International Date Line East */
};
#define NR_TZ (sizeof(timezone_names) / sizeof(timezone_names[0]))
static int match_string(const char *date, const char *str)
{
int i = 0;
for (i = 0; *date; date++, str++, i++) {
if (*date == *str)
continue;
if (toupper(*date) == toupper(*str))
continue;
if (!isalnum(*date))
break;
return 0;
}
return i;
}
static int skip_alpha(const char *date)
{
int i = 0;
do {
i++;
} while (isalpha(date[i]));
return i;
}
/*
* Parse month, weekday, or timezone name
*/
static int match_alpha(const char *date, struct tm *tm, int *offset)
{
int i;
for (i = 0; i < 12; i++) {
int match = match_string(date, month_names[i]);
if (match >= 3) {
tm->tm_mon = i;
return match;
}
}
for (i = 0; i < 7; i++) {
int match = match_string(date, weekday_names[i]);
if (match >= 3) {
tm->tm_wday = i;
return match;
}
}
for (i = 0; i < NR_TZ; i++) {
int match = match_string(date, timezone_names[i].name);
if (match >= 3) {
int off = timezone_names[i].offset;
/* This is bogus, but we like summer */
off += timezone_names[i].dst;
/* Only use the tz name offset if we don't have anything better */
if (*offset == -1)
*offset = 60*off;
return match;
}
}
if (match_string(date, "PM") == 2) {
if (tm->tm_hour > 0 && tm->tm_hour < 12)
tm->tm_hour += 12;
return 2;
}
/* BAD CRAP */
return skip_alpha(date);
}
static int is_date(int year, int month, int day, struct tm *tm)
{
if (month > 0 && month < 13 && day > 0 && day < 32) {
if (year == -1) {
tm->tm_mon = month-1;
tm->tm_mday = day;
return 1;
}
if (year >= 1970 && year < 2100) {
year -= 1900;
} else if (year > 70 && year < 100) {
/* ok */
} else if (year < 38) {
year += 100;
} else
return 0;
tm->tm_mon = month-1;
tm->tm_mday = day;
tm->tm_year = year;
return 1;
}
return 0;
}
static int match_multi_number(unsigned long num, char c, char *date, char *end, struct tm *tm)
{
long num2, num3;
num2 = strtol(end+1, &end, 10);
num3 = -1;
if (*end == c && isdigit(end[1]))
num3 = strtol(end+1, &end, 10);
/* Time? Date? */
switch (c) {
case ':':
if (num3 < 0)
num3 = 0;
if (num < 25 && num2 >= 0 && num2 < 60 && num3 >= 0 && num3 <= 60) {
tm->tm_hour = num;
tm->tm_min = num2;
tm->tm_sec = num3;
break;
}
return 0;
case '-':
case '/':
if (num > 70) {
/* yyyy-mm-dd? */
if (is_date(num, num2, num3, tm))
break;
/* yyyy-dd-mm? */
if (is_date(num, num3, num2, tm))
break;
}
/* mm/dd/yy ? */
if (is_date(num3, num2, num, tm))
break;
/* dd/mm/yy ? */
if (is_date(num3, num, num2, tm))
break;
return 0;
}
return end - date;
}
/*
* We've seen a digit. Time? Year? Date?
*/
static int match_digit(char *date, struct tm *tm, int *offset)
{
int n;
char *end;
unsigned long num;
num = strtoul(date, &end, 10);
/*
* Seconds since 1970? We trigger on that for anything after Jan 1, 2000
*/
if (num > 946684800) {
time_t time = num;
if (gmtime_r(&time, tm))
return end - date;
}
/*
* Check for special formats: num[:-/]num[same]num
*/
switch (*end) {
case ':':
case '/':
case '-':
if (isdigit(end[1])) {
int match = match_multi_number(num, *end, date, end, tm);
if (match)
return match;
}
}
/*
* None of the special formats? Try to guess what
* the number meant. We use the number of digits
* to make a more educated guess..
*/
n = 0;
do {
n++;
} while (isdigit(date[n]));
/* Four-digit year or a timezone? */
if (n == 4) {
if (num <= 1200 && *offset == -1) {
unsigned int minutes = num % 100;
unsigned int hours = num / 100;
*offset = hours*60 + minutes;
} else if (num > 1900 && num < 2100)
tm->tm_year = num - 1900;
return n;
}
/*
* NOTE! We will give precedence to day-of-month over month or
* year numebers in the 1-12 range. So 05 is always "mday 5",
* unless we already have a mday..
*
* IOW, 01 Apr 05 parses as "April 1st, 2005".
*/
if (num > 0 && num < 32 && tm->tm_mday < 0) {
tm->tm_mday = num;
return n;
}
/* Two-digit year? */
if (n == 2 && tm->tm_year < 0) {
if (num < 10 && tm->tm_mday >= 0) {
tm->tm_year = num + 100;
return n;
}
if (num >= 70) {
tm->tm_year = num;
return n;
}
}
if (num > 0 && num < 32) {
tm->tm_mday = num;
} else if (num > 1900) {
tm->tm_year = num - 1900;
} else if (num > 70) {
tm->tm_year = num;
} else if (num > 0 && num < 13) {
tm->tm_mon = num-1;
}
return n;
}
static int match_tz(char *date, int *offp)
{
char *end;
int offset = strtoul(date+1, &end, 10);
int min, hour;
int n = end - date - 1;
min = offset % 100;
hour = offset / 100;
/*
* Don't accept any random crap.. At least 3 digits, and
* a valid minute. We might want to check that the minutes
* are divisible by 30 or something too.
*/
if (min < 60 && n > 2) {
offset = hour*60+min;
if (*date == '-')
offset = -offset;
*offp = offset;
}
return end - date;
}
/* Gr. strptime is crap for this; it doesn't have a way to require RFC2822
(i.e. English) day/month names, and it doesn't work correctly with %z. */
void parse_date(char *date, char *result, int maxlen)
{
struct tm tm;
int offset, sign;
time_t then;
memset(&tm, 0, sizeof(tm));
tm.tm_year = -1;
tm.tm_mon = -1;
tm.tm_mday = -1;
tm.tm_isdst = -1;
offset = -1;
for (;;) {
int match = 0;
unsigned char c = *date;
/* Stop at end of string or newline */
if (!c || c == '\n')
break;
if (isalpha(c))
match = match_alpha(date, &tm, &offset);
else if (isdigit(c))
match = match_digit(date, &tm, &offset);
else if ((c == '-' || c == '+') && isdigit(date[1]))
match = match_tz(date, &offset);
if (!match) {
/* BAD CRAP */
match = 1;
}
date += match;
}
/* mktime uses local timezone */
then = my_mktime(&tm);
if (offset == -1)
offset = (then - mktime(&tm)) / 60;
if (then == -1)
return;
then -= offset * 60;
sign = '+';
if (offset < 0) {
offset = -offset;
sign = '-';
}
snprintf(result, maxlen, "%lu %c%02d%02d", then, sign, offset/60, offset % 60);
}
void datestamp(char *buf, int bufsize)
{
time_t now;
int offset;
time(&now);
offset = my_mktime(localtime(&now)) - now;
offset /= 60;
snprintf(buf, bufsize, "%lu %+05d", now, offset/60*100 + offset%60);
}