Re: [PATCH 0/2] MR6759: kernelbase: Make trailing slashes in CreateFileW set ERROR_PATH_NOT_FOUND

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about dlls/kernelbase/file.c:
>       */
>      if (status == STATUS_OBJECT_NAME_COLLISION)
>          SetLastError( ERROR_FILE_EXISTS );
> -
>    else if (status == STATUS_FILE_IS_A_DIRECTORY)
> -
>    {
> -
>        WCHAR last = filename[wcslen(filename) - 1];
> -
>        SetLastError(last == '\\' || last == '/' ? ERROR_PATH_NOT_FOUND : ERROR_ACCESS_DENIED);
> -
>    }

I believe this causes regression for some drivers that handle `IRP_MJ_CREATE` and may return `STATUS_FILE_IS_A_DIRECTORY` from there.

`NtCreateFile()` is ***not*** just a wrapper for `open()`. For custom devices like `\.\MyCustomDriver`, it delegates to the third-party driver. The third-party driver might return `STATUS_FILE_IS_A_DIRECTORY` *but* still expect it to be translated to `ERROR_ACCESS_DENIED` even with the trailing slash.

I suspect the real culprit is that `NtCreateFile()` is incorrectly translating Unix `EISDIR` to `STATUS_FILE_IS_A_DIRECTORY` *unconditionally*. In this case, the bug needs to be fixed in ntdll, not kernelbase.