Logging temp file useage ... a little advice would be appreciated

So I've got this patch (attached, against 8.2)

The goal is to track temp file usage as an aid to server tuning (such as
work_mem)

Most of the patch seems to work just dandy, except I'm getting weird
sizes reported:

2006-12-29 17:46:21 EST [45558]: [575-1] LOG:  temp file: size 140737488343776 path
base/32861/pgsql_tmp/pgsql_tmp45558.554

Seems a bit odd to have a 140T file on a 130G partition ...

I'm working on a FreeBSD 6.2 amd64 system.  The headers show stat.st_size to
be of type off_t, which appears to be a 64-bit int.  I figured that %ld
would be the correct format.

Am I hitting something such as file sparseness?  Is this entire endeavour
doomed from the start?  Or am I just making some sort of dumb mistake?

Any pointers are welcome.

--
Bill Moran
Collaborative Fusion Inc.