Re: Date handling.

From: David Woodhouse <dwmw2@infradead.org>
Date: Apr 14, 2005, 17:38 UTC
Message-ID: <1113500316.27227.8.camel@hades.cambridge.redhat.com>
In-Reply-To: <Pine.LNX.4.58.0504140212100.7211@ppc970.osdl.org>

On Thu, 2005-04-14 at 02:12 -0700, Linus Torvalds wrote:

> I take that back. I'd be much happier with you doing and testing it, 
> because now I'm crashing.

OK. commit-tree now eats RFC2822 dates as AUTHOR_DATE because that's what you're going to want to feed it. We store seconds since UTC epoch, we add the author's or committer's timezone as auxiliary data so that dates can be pretty-printed in the original timezone later if anyone cares. I left the date parsing in rev-tree.c for backward compatibility but it can be dropped when we change to base64 :)

Yes, glibc sucks and strptime is a pile of crap. We have to parse it ourselves.

Index: commit-tree.c
--- 1756b578489f93999ded68ae347bef7d6063101c/commit-tree.c  (mode:100664 sha1:12196c79f31d004dff0df1f50dda67d8204f5568)
+++ 82ba574c85e9a2e4652419c88244e9dd1bfa8baa/commit-tree.c  (mode:100644 sha1:35cb09402c9868499bcaf6de42afbad9fdfebe05)
@@ -7,6 +7,9 @@
 
 #include <pwd.h>
 #include <time.h>
+#include <string.h>
+#include <ctype.h>
+#include <time.h>
 
 #define BLOCKING (1ul << 14)
 #define ORIG_OFFSET (40)
@@ -95,6 +98,148 @@
 	}
 }
 
+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. */
+static void parse_rfc2822_date(char *date, char *result, int maxlen)
+{
+	struct tm tm;
+	char *p;
+	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 (isspace(*p))
+		goto zone;
+
+	if (*p != ':')
+		return; /* Error -- bad time */
+	p++;
+
+	/* second */
+	if (!isdigit(*p))
+		return;
+	tm.tm_sec = strtoul(p, &p, 10);
+	
+	if (!tm.tm_sec > 59)
+		return;
+
+	if (!isspace(*p))
+		return;
+
+ zone:
+	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;
+
+	i = strtoul(p+1, NULL, 10);
+	offset *= ((i % 100) + ((i / 100) * 60));
+
+	if (*(skipfws(p + 5)))
+		return;
+
+	then = mktime(&tm); /* mktime appears to ignore the GMT offset, stupidly */
+	if (then == -1)
+		return;
+
+	then -= offset;
+
+	snprintf(result, maxlen, "%lu %5.5s", then, p);
+}
+
 /*
  * Having more than two parents may be strange, but hey, there's
  * no conceptual reason why the file format couldn't accept multi-way
@@ -114,10 +259,12 @@
 	unsigned char commit_sha1[20];
 	char *gecos, *realgecos;
 	char *email, realemail[1000];
-	char *date, *realdate;
+	char date[20], realdate[20];
+	char *audate;
 	char comment[1000];
 	struct passwd *pw;
 	time_t now;
+	struct tm *tm;
 	char *buffer;
 	unsigned int size;
 
@@ -142,15 +289,19 @@
 	realemail[len] = '@';
 	gethostname(realemail+len+1, sizeof(realemail)-len-1);
 	time(&now);
-	realdate = ctime(&now);
+	tm = localtime(&now);
+
+	strftime(realdate, sizeof(realdate), "%s %z", tm);
+	strcpy(date, realdate);
 
 	gecos = getenv("AUTHOR_NAME") ? : realgecos;
 	email = getenv("AUTHOR_EMAIL") ? : realemail;
-	date = getenv("AUTHOR_DATE") ? : realdate;
+	audate = getenv("AUTHOR_DATE");
+	if (audate)
+		parse_rfc2822_date(audate, date, sizeof(date));
 
 	remove_special(gecos); remove_special(realgecos);
 	remove_special(email); remove_special(realemail);
-	remove_special(date); remove_special(realdate);
 
 	init_buffer(&buffer, &size);
 	add_buffer(&buffer, &size, "tree %s\n", sha1_to_hex(tree_sha1));
Index: rev-tree.c
--- 1756b578489f93999ded68ae347bef7d6063101c/rev-tree.c  (mode:100664 sha1:7bf9e9a92f528485360f374239809714ce7a19f5)
+++ 82ba574c85e9a2e4652419c88244e9dd1bfa8baa/rev-tree.c  (mode:100644 sha1:9443f4560beedcf81f2f5e7e0664d169cb5c8527)
@@ -1,4 +1,5 @@
 #define _XOPEN_SOURCE /* glibc2 needs this */
+#define _BSD_SOURCE /* for tm.tm_gmtoff */
 #include <time.h>
 #include <ctype.h>
 
@@ -21,6 +22,7 @@
 	char buffer[100];
 	struct tm tm;
 	const char *formats[] = {
+		"%s",
 		"%c",
 		"%a %b %d %T %y",
 		NULL
@@ -30,7 +32,7 @@
 	p = buffer;
 	while (isspace(c = *buf))
 		buf++;
-	while ((c = *buf++) != '\n')
+	while ((c = *buf++) != '\n' && c)
 		*p++ = c;
 	*p++ = 0;
 	buf = buffer;
@@ -50,6 +52,8 @@
 
 static unsigned long parse_commit_date(const char *buf)
 {
+	unsigned long time;
+
 	if (memcmp(buf, "author", 6))
 		return 0;
 	while (*buf++ != '\n')
@@ -58,7 +62,11 @@
 		return 0;
 	while (*buf++ != '>')
 		/* nada */;
-	return parse_time(buf);
+
+	time = strtoul(buf, NULL, 10);
+	if (!time)
+		time = parse_time(buf);
+	return time;
 }
 
 static int parse_commit(unsigned char *sha1)

-- 
dwmw2