[PATCH] Do date parsing by hand...

...since everything out there is either strange (libc mktime has issues
with timezones) or introduces unnecessary dependencies for people (libcurl).

This goes back to the old date parsing, but moves it out into a file of
its own, and does the "struct tm" to "seconds since epoch" handling by
hand. 

I grepped through the tz-database and it seems there's one "country"
left that has non-60-minute DST: Lord Howe Island.  All others dropped
that before 1970. 

1 files changed, 184 insertions, 0 deletions

diff --git a/date.c b/date.c
new file mode 100644
index 0000000000..1e43936f8e
--- /dev/null
+++ b/date.c
@@ -0,0 +1,184 @@
+/*
+ * 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[] = {
+        "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+        "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+};
+
+static const char *weekday_names[] = {
+        "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+};
+
+
+static char *skipfws(char *str)
+{
+	while (isspace(*str))
+		str++;
+	return str;
+}
+
+	
+/* 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;
+	char *p, *tz;
+	int i, offset;
+	time_t then;
+
+	memset(&tm, 0, sizeof(tm));
+
+	/* Skip day-name */
+	p = skipfws(date);
+	if (!isdigit(*p)) {
+		for (i=0; i<7; i++) {
+			if (!strncmp(p,weekday_names[i],3) && p[3] == ',') {
+				p = skipfws(p+4);
+				goto day;
+			}
+		}
+		return;
+	}					
+
+	/* day */
+ day:
+	tm.tm_mday = strtoul(p, &p, 10);
+
+	if (tm.tm_mday < 1 || tm.tm_mday > 31)
+		return;
+
+	if (!isspace(*p))
+		return;
+
+	p = skipfws(p);
+
+	/* month */
+
+	for (i=0; i<12; i++) {
+		if (!strncmp(p, month_names[i], 3) && isspace(p[3])) {
+			tm.tm_mon = i;
+			p = skipfws(p+strlen(month_names[i]));
+			goto year;
+		}
+	}
+	return; /* Error -- bad month */
+
+	/* year */
+ year:	
+	tm.tm_year = strtoul(p, &p, 10);
+
+	if (!tm.tm_year && !isspace(*p))
+		return;
+
+	if (tm.tm_year > 1900)
+		tm.tm_year -= 1900;
+		
+	p=skipfws(p);
+
+	/* hour */
+	if (!isdigit(*p))
+		return;
+	tm.tm_hour = strtoul(p, &p, 10);
+	
+	if (tm.tm_hour > 23)
+		return;
+
+	if (*p != ':')
+		return; /* Error -- bad time */
+	p++;
+
+	/* minute */
+	if (!isdigit(*p))
+		return;
+	tm.tm_min = strtoul(p, &p, 10);
+	
+	if (tm.tm_min > 59)
+		return;
+
+	if (*p != ':')
+		goto zone;
+	p++;
+
+	/* second */
+	if (!isdigit(*p))
+		return;
+	tm.tm_sec = strtoul(p, &p, 10);
+	
+	if (tm.tm_sec > 60)
+		return;
+
+ zone:
+	if (!isspace(*p))
+		return;
+
+	p = skipfws(p);
+
+	if (*p == '-')
+		offset = -60;
+	else if (*p == '+')
+		offset = 60;
+	else
+	       return;
+
+	if (!isdigit(p[1]) || !isdigit(p[2]) || !isdigit(p[3]) || !isdigit(p[4]))
+		return;
+
+	tz = p;
+	i = strtoul(p+1, NULL, 10);
+	offset *= ((i % 100) + ((i / 100) * 60));
+
+	p = skipfws(p + 5);
+	if (*p && *p != '(') /* trailing comment like (EDT) is ok */
+		return;
+
+	then = my_mktime(&tm); /* mktime uses local timezone */
+	if (then == -1)
+		return;
+
+	then -= offset;
+
+	snprintf(result, maxlen, "%lu %5.5s", then, tz);
+}
+
+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);
+}