[fpc-pascal] DoDirSeparators and special filenames on Windows

[Sven Barth]

On 08.09.2013 14:17, Bart wrote:
> On 9/8/13, Tomas Hajny <XHajT03 at hajny.biz> wrote:
>
>> Why do you believe that ExpandFilename is not threadsafe (on Windows or
>> any other platform)?
> ..
>> The only platform specific part inside
>> ExpandFilename is a call to GetDir function retrieving the current
>> directory. If that is not 'threadsafe' by itself (on Windows), then your
>> statement is correct,
>
> And that is exactly the point.
> GetDir calls GetCurentDirectory and MS says (see:
> http://msdn.microsoft.com/en-us/library/windows/desktop/aa364934%28v=vs.85%29.aspx)
> that multithreaded applications should not call GetCurrentDirectory.

The problem is not GetCurrentDirectory itself (this function and 
SetCurrentDirectory use the process's PEB lock to access the current 
directory which is stored inside the PEB as well), but that different 
threads could call SetCurrentDirectory with different values and thus a 
thread who expected the current directory to be a specific one might 
resolve a relative path (by using another WinAPI function) using a 
current directory set by a different thread.

So this can not be solved by using a lock inside ExpandFilename and 
might happen on other systems as well as long as the current directory 
is not stored per thread.

Regards,
Sven