CopyFileEx and 8.3 file names

Question

Suppose you have 2 files in the same directory:

New File Name.txt and NewFil~1.txt

If you use CopyFileEx to copy both files to the same destination, maintaining the same names, you will end up having only ONE file (the second one replaces the first one) which can be sometimes not a good thing. Any workaround for this behavior?

Answer 1

There's not a great solution for the automatic generation of short filename aliases. If your application will have adequate privileges, you might be able to use the SetFileShortName() API. Another (heavy handed) alternative might be to disable short name alias generation altogether, though I'd be reluctant to require this of your users. See

• http://support.microsoft.com/kb/210638/EN-US/
• http://technet.microsoft.com/en-us/library/cc778996.aspx
• http://blogs.msdn.com/adioltean/archive/2005/01/27/362105.aspx

for more details.

Answer 2

This happens at file system level so you there is no much you can do if you don't want to disable SFN generation at all.

The way I use to handle this problem is to:

1) Before the file is copied, I check if the file name exists. 2) If there is a collision then I first rename the existing file top some temporary name 3) Then I copy the file 4) rename the first file back.

To detect the collision do something like this:

function IsCollition(const Source, Destination: string; var ExistingName: string): boolean;
var
  DesFD: TSearchRec;
  Found: boolean;
  ShortSource, FoundName: string;
begin
  ShortSource:= ExtractFileName(SourceName);
  Found:= false;
  FoundName:= WS_NIL;

  if (FindFirst(DestinationName, faAnyFile, DesFD) = 0) then
  begin
    Found:= true;
    FoundName:= DesFD.Name;
    SysUtils.FindClose(DesFD);
  end;

  if (not Found) or (SameFileName(ShortSource, FoundName)) then
  begin
    Result:= false;
  end else
  begin
    // There iis a collision:
    // A  file exists AND it's long name is not equal to the original name
    Result:= true;
  end;

  ExistingName:= FoundName;
end;