Behaviour of os.path.join

[BlindAnagram]

On 28/05/2020 14:51, Eryk Sun wrote:
> On 5/27/20, Chris Angelico <rosuav at gmail.com> wrote:
>> On Thu, May 28, 2020 at 7:07 AM BlindAnagram <blindanagram at nowhere.com>
>> wrote:
>>> You can define a path however you want but it won't change the fact that
>>> on Windows a path that ends in '\\' is inherently a path to a directory.
>>
>> Citation needed.
> 
> See [MS-FSA] 2.1.5.1 Server Requests an Open of a File [1]. Here are
> the relevant statements:
> 
>     The operation MUST be failed with STATUS_OBJECT_NAME_INVALID under
>     any of the following conditions:
>     ....
>       * If PathName contains a trailing backslash and
>         CreateOptions.FILE_NON_DIRECTORY_FILE is TRUE.
> 
>     ....
>     If PathName contains a trailing backslash:
>       * If StreamTypeToOpen is DataStream or
>         CreateOptions.FILE_NON_DIRECTORY_FILE is TRUE, the operation MUST
>         be failed with STATUS_OBJECT_NAME_INVALID
> 
> Internally, WinAPI CreateFileW calls NTAPI NtCreateFile with the
> create option FILE_NON_DIRECTORY_FILE (i.e. only open or create a data
> file stream), unless backup semantics are requested in order to be
> able to open a directory (i.e. an index stream), in which case the
> call uses neither FILE_NON_DIRECTORY_FILE nor FILE_DIRECTORY_FILE and
> leaves it up to the path name. In other words, with backup semantics,
> if you need to ensure that only a directory is opened, add a trailing
> slash.
> 
> NTAPI STATUS_OBJECT_NAME_INVALID translates to WinAPI
> ERROR_INVALID_NAME (123), which translates to C EINVAL (22).
> 
> [1]: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-fsa/8ada5fbe-db4e-49fd-aef6-20d54b748e40
> 
Thank you for making the effort to answer a number of issues raaised in
this thread.  I much appreciate your input.