Mark H Weaver <mhw@netris.org> writes:

> David Kastrup <dak@gnu.org> writes:
>
>> (use-modules (rnrs bytevectors) (rnrs io ports))
>> (let ((port (open-bytevector-input-port
>> 	     (string->utf8 "Blablabla\nBlablabla\n"))))
>>   (seek port 13 SEEK_SET)
>>   (format #t "~c ~d\n" (peek-char port)
>> 	  (ftell port)))
>> ;; Outputs b 3 but should output b 13
>>
>> This is using
>> guile (GNU Guile) 2.0.11
>> Packaged by Debian (2.0.11-deb+1-1)
>
> Ouch :-(
>
> The problem is that r6rs-ports.c:bip_seek assumes that
> c_port->read_{buf,pos,end} point to the original bytevector, and fail to
> handle the case where it points to a "putback" buffer.
>
> Note that (ftell port) is equivalent to (seek port 0 SEEK_CUR).

I've attached a preliminary patch set to fix this bug and some others.
I'm going to hold off on pushing them to stable-2.0 until I've added
tests and convinced myself that I haven't introduced any new problems.

     Mark