When printing an USB string descriptor using pdesc/pstring,
strings have one additional character at the end.

In pstring(/sys/src/cmd/usb/lib/dump.c:297) the descriptor length in
buf[0] is interpreted as the number of bytes in the following Unicode string,
but, compared to the spec, this is two bytes (or one Rune)
too much.

Apparently buf[0] is `the number of bytes 
within the string + 2' (for descriptor length and type).

The patch tries to fix it by reducing `n' by 2 before using it.

Reference: /n/sources/patch/applied/libusb-fix-strlen
Date: Fri Oct 13 21:23:17 CES 2006
Signed-off-by: mt@wmipf.in-berlin.de

--- /sys/src/cmd/usb/lib/dump.c	Fri Oct 13 21:18:58 2006
+++ /sys/src/cmd/usb/lib/dump.c	Fri Oct 13 21:18:44 2006
@@ -309,7 +309,7 @@
 		fprint(2, "illegal count\n");
 		return;
 	}
-	n /= 2;
+	n = (n - 2)/2;
 	rb = (byte*)b + 2;
 	s = malloc(n*UTFmax+1);
 	for(l=0; --n >= 0; rb += 2){