first usable version of kernel and commands

After an year of hard work, this is a first "usable" version of Jehanne.

sys/src/lib/c/port/utfecpy.c

@@ -0,0 +1,30 @@
+/*
+ * This file is part of the UCB release of Plan 9. It is subject to the license
+ * terms in the LICENSE file found in the top-level directory of this
+ * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
+ * part of the UCB release of Plan 9, including this file, may be copied,
+ * modified, propagated, or distributed except according to the terms contained
+ * in the LICENSE file.
+ */
+
+#include <u.h>
+#include <libc.h>
+
+char*
+utfecpy(char *to, char *e, const char *from)
+{
+	char *end;
+
+	if(to >= e)
+		return to;
+	end = memccpy(to, from, '\0', e - to);
+	if(end == nil){
+			end = e;
+		while(end>to && (*--end&0xC0)==0x80)
+			;
+		*end = '\0';
+	}else{
+		end--;
+	}
+	return end;
+}