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Date: Tue, 21 Feb 2012 10:26:05 +0000
Message-ID: <CADSoG1sCUeC=6UCmTmb56pWFoDM0mR9+RT0ozGNRtiaMPsbBCA@mail.gmail.com>
Subject: Re: shared_info::init_obcaseinsensitive implemented incorrectly
From: Nick Lowe <nick DOT lowe AT gmail DOT com>
To: cygwin AT cygwin DOT com
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I have just tested this and it works. It is faster, simpler and has
less overheads than querying the registry for a potentially stale
value.

Just call NtOpenSymbolicLinkObject for \SYSTEMROOT with a
DesiredAccess of 0 and no attributes flags in the OBJECT_ATTRIBUTES
structure.

This will fail with STATUS_ACCESS_DENIED if the system is running with
case insensitivity and STATUS_OBJECT_NAME_NOT_FOUND if running with
case sensitivity.

For correctness, on the off chance that a successful NTSTATUS value is
returned, the system is running with case insensitivity and the handle
must be closed.

Regards,

Nick

On Tue, Feb 21, 2012 at 9:52 AM, Nick Lowe <nick DOT lowe AT gmail DOT com> wrote:
> OK, fair enough, it is an edge case... I am a stickler for correctness! :P
>
> Looking at previous threads though actually, I notice that the
> following is documented by Microsoft regarding the obcaseinsensitive
> value:
>
> "If this setting is enabled, case insensitivity is enforced for all
> directory objects, symbolic links, and IO objects, including file
> objects. Disabling this setting does not allow the Win32 subsystem to
> become case sensitive."
>
> You could just get away with therefore, in theory, a call to
> NtOpenSymbolicLinkObject for \SYSTEMROOT. If it fails because it
> cannot be found, you know that the system is running with case
> sensitivity, otherwise, it is case sensitive.
>
> Regards,
>
> Nick

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