Re: Issue when trying to access files on a locked BitLocker volume

[Brian Inglis <Brian dot Inglis at SystematicSw dot ab dot ca>]

On 2018-04-19 07:45, Corinna Vinschen wrote:
> On Apr 19 13:38, Vincent Gheur wrote:
>> Hi,
>>
>> I'm using a Bitlocker encrypted SD card, which stays most of the time in my
>> laptop, but is generally not unlocked. I'm unlocking it only when I need to
>> access files on it.
>>
>> I have also a script which is started at regular intervals, which copies
>> some critical files on the SD card when it is unlocked. I was using till
>> recently a *very* old version of cygwin (probably downloaded 10 years ago),
>> in which I could check whether my SD card was unlocked or not by using *if
>> [ -d <folder-on-SD-card> ]*. I have downloaded a new version of cygwin in
>> January, as I migrated to Windows 10 and was encountering some issues with
>> it. Since I upgraded, this test is not working anymore. When the SD card is
>> unlocked, testing " -d <folder> " returns TRUE. It returns FALSE when I do
>> the same test on a non Bitlocker volume for a non-existent folder (which is
>> the expected behaviour).
> 
> I'm not sure I understand.
> 
> You're testing with -d <non-existing-folder> if the drive is unlocked?
> And you're expecting... what exactly?  The test should return FALSE in
> all cases, regardless of the drive being locked or unlocked.
> 
> Sure, it sounds wrong if -d <non-existing-folder> returns TRUE, but
> I wonder if I misunderstand what you're doing.
> 
> Can you rephrase this to make it more clear?
> 
> Also, can you create an strace of the wrong behaviour to see if there's
> a certain error or NT status code which indicates the problem to be
> handled more correctly?

ISTM he's saying (badly) he's testing for an *existing* BitLocker folder which
should only be accessible when the volume is unlocked, but current Cygwin
returns that the folder is accessible, even when the volume should be locked.
Sounds like current Windows may be being "helpful" or caching volume info.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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