Add isotime() and isodate() functions to libc.

1 files changed, 47 insertions, 0 deletions

diff --git a/sys/src/libc/9sys/ctime.c b/sys/src/libc/9sys/ctime.c
index 11340ea41..a99727225 100644
--- a/sys/src/libc/9sys/ctime.c
+++ b/sys/src/libc/9sys/ctime.c
@@ -299,3 +299,50 @@ rd_long(char **f, long *p)
 	*p = l;
 	return 0;
 }
+
+char*
+isodate(Tm *t)
+{
+	static char c[10+14+1]; /* leave room to append isotime */
+
+	ct_numb(c, t->year / 100 + 119);
+	ct_numb(c+2, t->year % 100 + 100);
+	c[4] = '-';
+	ct_numb(c+5, t->mon + 101);
+	c[7] = '-';
+	ct_numb(c+8, t->mday + 100);
+	c[10] = 0;
+	return c;
+}
+
+char*
+isotime(Tm *t)
+{
+	int tz;
+	char *c, *d;
+	d = isodate(t);
+	c = d + 10; /* append to isodate */
+	c[0] = 'T';
+	ct_numb(c+1, t->hour+100);
+	c[3] = ':';
+	ct_numb(c+4, t->min+100);
+	c[6] = ':';
+	ct_numb(c+7, t->sec+100);
+	tz = t->tzoff / 60;
+	if(t->tzoff) {
+		/* localtime */
+		if (t->tzoff > 0) {
+			c[9] = '+';
+		} else {
+			c[9] = '-';
+			tz = -tz;
+		}
+		ct_numb(c+10, tz / 60 + 100);
+		ct_numb(c+12, tz % 60 + 100);
+		c[14] = 0;
+	} else {
+		c[9] = 'Z';
+		c[10] = 0;
+	}
+	return d;
+}