Subject UDF for checking if an external file exists
Author Helmut Steinberger

I need an UDF that checks if an external file exists (in fact I need
an udf getting data from that file and return it as blob, but to make
it more easy i reduce the problem to the basic).
I allready found a way to do so, but unfortunately it doesn't work
with mapped directories or UNC pathnames.
It only works with the local pathname.

This is an example udf:

function check_filename (fn: PChar): integer; cdecl; export;

if fileexists (sz) then
result := 1
result := 0;

if I call

select check_filename ('c:\myfile') from rdb$database

it works.

select check_filename ('\\server\server_c\myfile') from rdb$database

does not work.

select check_filename ('f:\myfile') from rdb$database

where f: is mapped to c:\ on server, does not work.

How could I get fileexist working on a network path?

As I told above, I need to get data from the external file to return
it as blob. This is not the problem. This allready works with local
pathnames, so I only habe to solve the fileexists (and finally the
loadfromfile) problem with remote pathnames.

Kind regards