utfecpy() ignores any valid UTF sequence
at the end of its input.

for example:
	utfecpy(to, to+5, "1234567890");
copies only 3 bytes while
	strecpy(to, to+5, "1234567890");
copies 4.  also,
	utfecpy(to, to+7, "123க456");
copies only the first 3 bytes.

this patch replaces utfecpy() with a modified
version of /acme/bin/source/win/main.c:/^utfncpy

thanks.
arvindh

Notes:
Wed May 24 10:54:10 EDT 2006 rsc
    Thanks!  I put in an even simpler fix.
    


Reference: /n/sources/patch/applied/utfecpy-boundary
Date: Mon May 22 22:41:16 CES 2006
Signed-off-by: arvindht@gmail.com
Reviewed-by: rsc

--- /sys/src/libc/port/utfecpy.c	Mon May 22 22:40:45 2006
+++ /sys/src/libc/port/utfecpy.c	Mon May 22 22:40:38 2006
@@ -11,8 +11,14 @@
 	end = memccpy(to, from, '\0', e - to);
 	if(end == nil){
 		end = e-1;
-		while(end>to && (*--end&0xC0)==0x80)
-			;
+		if(end>to && end[-1]&0x80){
+			if(end-2>=to && (end[-2]&0xE0)==0xC0){
+				;
+			}else if(end-3>=to && (end[-3]&0xF0)==0xE0){
+				;
+			}else while(end>to && (*--end&0xC0)==0x80)
+				;
+		}
 		*end = '\0';
 	}else{
 		end--;