https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108350
--- Comment #22 from Bill Zissimopoulos <gnu.org at billz dot fastmail.fm> ---
(In reply to niXman from comment #21)
> another strange problem is that `CreateFile()` is able to open the special
> file `nul` for reading, but `GetFinalPathNameByHandle()` cannot get the full
> name of this file and returns 0 and setting `last error` to
> `ERROR_INVALID_PARAMETER`.
>
> and so you don't get bored I'll add: `GetFullPathName()` can get the full
> name of such a file.
>
> (how could this happen? %) )
Yes :)
GetFinalPathNameByHandle internally performs a special request that only file
system drivers respond to (IRP_MJ_QUERY_INFORMATION /
FileNormalizedNameInformation).
So a path like X:\Path\To\File will be resolved to an internal path like:
\Device\<XVOLDEVICE>\Path\To\File
Now \Device\<XVOLDEVICE> is a file system driver (or points to one via an
elaborate mechanism, but let's not complicate matters further) and knows how to
respond to FileNormalizedNameInformation queries.
OTOH a path like nul will be resolved to an internal path like:
\Device\Null
This is a simple device and not a file system driver and does not know how to
respond to FileNormalizedNameInformation queries.
So GetFinalPathNameByHandle works on the first, but not the second.
As for GetFullPathName: I think it works by doing simple string manipulations
on the path (i.e. no attempts to open the file and query its path, etc.)
