Do you still get this with current versions? I get the correct error dialog (A file named "custom-printf.c" already exists.  Do you want to replace it?).

We debugged this, the core cause for this is that the libsmbclient create() call doesn't correctly give an EEXIST error when the O_EXCL flag is used and the file already exists.

This works on samba and windows xp shares, but the apparently it fails for a LanDrive: http://www.mediacase.co.uk/

This is somewhat similar to bug 515963

Sebastien: Can you get a tcp dump against the landrive when you run the create program. Something like "tcpdump -s0 -w dumpfile.cap -i eth0"

Created attachment 105349 [details]
create test log

The log has been made using wireshark, that should be compatible with what tcpdump is doing

<simo> alex, the Open and X response from that thing, seem messed up
<simo> it returns an 0x00500001 NT status error
<simo> which makes no sense
<simo> (status errors are always 0x0c00...
<simo> at least for this stuff
<alex> i had a short look at it with wireshark
<simo> alex, unless the guy is not captuing the full packet
<alex> and as much as i could understand the sent request had "error if file already exists" set
<simo> alex, yeah but the packet returned by the filer is half-broken
<simo> that's probably why libsmbclient can't correctly decipher it
<simo> it's an appliance problem
<simo> maybe windows replies something sensible here
<simo> alex, ask this guy to see what happens if he uses smbclient from the CLI
<alex> simo: how do you get that to do an exclusive open?
<simo> se Fail if exist flag?
<alex> yeah
<simo> though libsmbclient ?
<alex> from the smbclient CLI
<simo> hmmm good question
<simo> not sure you can indeed

smbc has a similar issue, when trying to upload a different file with the same name it doesn't prompt about the overwrite and doesn't copy anything 

Created attachment 105520 [details]
wireshark log when running smbc and trying to upload

Same issue there. The open request reply is:
NT Status: Unknown (0x00500001)

Whereas on a test i did vs a samba server its correct:
NT Status: STATUS_SUCCESS (0x00000000)

That server seems quite nasty...

Here's a repository of firmware updates that might help on the LanDrive side. Maybe it's been fixed there? Unless this is too little too late :-)

If this is still a problem, it should be worked around in libsmbclient.