git/date.c
Linus Torvalds 89967023da Make the date parsing accept pretty much any random crap.
This date parser turns line-noise into a date. Cool.
2005-04-30 13:19:56 -07:00

294 lines
6.5 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"
};
/*
* 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;
} timezone_names[] = {
{ "IDLW", -12 }, /* International Date Line West */
{ "NT", -11 }, /* Nome */
{ "CAT", -10 }, /* Central Alaska */
{ "HST", -10 }, /* Hawaii Standard */
{ "HDT", -9 }, /* Hawaii Daylight */
{ "YDT", -8 }, /* Yukon Daylight */
{ "YST", -9 }, /* Yukon Standard */
{ "PST", -8 }, /* Pacific Standard */
{ "PDT", -7 }, /* Pacific Daylight */
{ "MST", -7 }, /* Mountain Standard */
{ "MDT", -6 }, /* Mountain Daylight */
{ "CST", -6 }, /* Central Standard */
{ "CDT", -5 }, /* Central Daylight */
{ "EST", -5 }, /* Eastern Standard */
{ "EDT", -4 }, /* Eastern Daylight */
{ "AST", -3 }, /* Atlantic Standard */
{ "ADT", -2 }, /* Atlantic Daylight */
{ "WAT", -1 }, /* West Africa */
{ "GMT", 0 }, /* Greenwich Mean */
{ "UTC", 0 }, /* Universal (Coordinated) */
{ "WET", 0 }, /* Western European */
{ "BST", 0 }, /* British Summer */
{ "CET", +1 }, /* Central European */
{ "MET", +1 }, /* Middle European */
{ "MEWT", +1 }, /* Middle European Winter */
{ "MEST", +2 }, /* Middle European Summer */
{ "CEST", +2 }, /* Central European Summer */
{ "MESZ", +1 }, /* Middle European Summer */
{ "FWT", +1 }, /* French Winter */
{ "FST", +2 }, /* French Summer */
{ "EET", +2 }, /* Eastern Europe, USSR Zone 1 */
{ "WAST", +7 }, /* West Australian Standard */
{ "WADT", +8 }, /* West Australian Daylight */
{ "CCT", +8 }, /* China Coast, USSR Zone 7 */
{ "JST", +9 }, /* Japan Standard, USSR Zone 8 */
{ "EAST", +10 }, /* Eastern Australian Standard */
{ "EADT", +11 }, /* Eastern Australian Daylight */
{ "GST", +10 }, /* Guam Standard, USSR Zone 9 */
{ "NZT", +11 }, /* New Zealand */
{ "NZST", +11 }, /* New Zealand Standard */
{ "NZDT", +12 }, /* New Zealand Daylight */
{ "IDLE", +12 }, /* 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;
}
/*
* 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) {
*offset = 60*timezone_names[i].offset;
return match;
}
}
/* BAD CRAP */
return 0;
}
static int match_digit(char *date, struct tm *tm, int *offset)
{
char *end, c;
unsigned long num, num2, num3;
num = strtoul(date, &end, 10);
/* Time? num:num[:num] */
if (num < 24 && end[0] == ':' && isdigit(end[1])) {
tm->tm_hour = num;
num = strtoul(end+1, &end, 10);
if (num < 60) {
tm->tm_min = num;
if (end[0] == ':' && isdigit(end[1])) {
num = strtoul(end+1, &end, 10);
if (num < 61)
tm->tm_sec = num;
}
}
return end - date;
}
/* Year? Day of month? Numeric date-string?*/
c = *end;
switch (c) {
default:
if (num > 0 && num < 32) {
tm->tm_mday = num;
break;
}
if (num > 1900) {
tm->tm_year = num - 1900;
break;
}
if (num > 70) {
tm->tm_year = num;
break;
}
break;
case '-':
case '/':
if (num && num < 32 && isdigit(end[1])) {
num2 = strtoul(end+1, &end, 10);
if (!num2 || num2 > 31)
break;
if (num > 12) {
if (num2 > 12)
break;
num3 = num;
num = num2;
num2 = num3;
}
tm->tm_mon = num - 1;
tm->tm_mday = num2;
if (*end == c && isdigit(end[1])) {
num3 = strtoul(end, &end, 10);
if (num3 > 1900)
num3 -= 1900;
tm->tm_year = num3;
}
break;
}
}
return end - date;
}
static int match_tz(char *date, int *offp)
{
char *end;
int offset = strtoul(date+1, &end, 10);
int min, hour;
min = offset % 100;
hour = offset / 100;
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;
time_t then;
memset(&tm, 0, sizeof(tm));
tm.tm_year = -1;
tm.tm_mon = -1;
tm.tm_mday = -1;
offset = 0;
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;
}
then = my_mktime(&tm); /* mktime uses local timezone */
if (then == -1)
return;
then -= offset * 60;
snprintf(result, maxlen, "%lu %+03d%02d", then, 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);
}