Bug in libpq large-object interface

Hi PostgreSQL people in general and Tatsuo in particular,

I'm using V 7.0 on a Linux machine and I believe I have found a bug in the
large object interface provided by libpq.  The code below will reproduce it, I
hope.  Basically it creates a large object, writes six 'a' characters to it,
then closes it.  Then, in another transaction, it opens the object, seeks to
position 1 from the start, writes a 'b', then seeks to position 3 from the
start and writes another 'b'. Then it closes the object and COMMITs the
transaction.  Finally, in a further separate transaction, it calls lo_export
to write out the resulting object to a file testloseek.c.lobj  I find this
file, instead of containing the string 'ababaa' as expected, contains
'^@b^@baa' where ^@ is ASCII NUL.

Compile with something like

       gcc -o testloseek testloseek.c -lpq

The program sets the PQtrace to STDOUT and writes messages to STDERR, so run
it with STDOUT redirected to a log file.

This is a C version of a basic regression test of guile-pg, my Guile language
bindings for libpq.  You may recall I reported a similar bug a year or so ago,
and I believed it was then fixed by Tatsuo, after a couple of iterations.  I'm
sorry to be the bearer of bad news ...

Please reply to me directly since I'm not on the list.

Thanks
Ian
--
Ian Grant, Computer Lab., New Museums Site, Pembroke Street, Cambridge
Phone: +44 1223 334420          Personal e-mail: iang at pobox dot com