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Date: Fri, 8 Mar 2024 17:26:38 -0500
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Subject: Re: ls/stat on OneDrive causes download of files
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To: cygwin@cygwin.com, Jeffrey Altman <jaltman@secure-endpoints.com>,
        Thomas Wolff <towo@towo.net>
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In-Reply-To: <ZeuPT82dRN2RfzHi@calimero.vinschen.de>
From: Marcin Wisnicki via Cygwin <cygwin@cygwin.com>
Reply-To: Marcin Wisnicki <mwisnicki@gmail.com>
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On 2024-03-08 17:21, Corinna Vinschen wrote:
> On Mar  8 14:56, Corinna Vinschen via Cygwin wrote:
>> On Mar  8 08:15, Jeffrey Altman via Cygwin wrote:
>>> On 3/8/2024 7:52 AM, Thomas Wolff via Cygwin wrote:
>>>> Am 08.03.2024 um 11:37 schrieb Corinna Vinschen via Cygwin:
>>>>>     FILE_OPEN_NO_RECALL (0x00400000)
>>>>> [...]
>>>>> This sounds like we could simply add this flag to all NtOpenFile
>>>>> used for path conversion or stat-like calls, without having to care
>>>>> for any file attributes specificially.
>>>>>
>>>>> Does that make sense?
>>>> Sounds good, without even studying the other details...
>>>> I speculate some more handling would still be needed to avoid executable
>>>> detection via magic tags.
>>>>
>>> Agreed.   FILE_OPEN_NO_RECALL has been defined for at least a decade but was
>>> not documented by Microsoft relatively recently.
>> Thanks for the feedback, guys.
>>
>>> Another suggestion would be to try opening the file with
>>> FILE_READ_ATTRIBUTES instead of GENERIC_READ if the file data is not
>>> required.  See
>>>
>>> https://github.com/microsoft/BuildXL/commit/4fb8e7ce07d243ccd95de0d66da551538a794493
>> Cygwin uses the minimum of required permissions in NtCreateFile/
>> NtOpenFile calls anyway.
>>
>> I'm just running a test cygwin DLL locally with a lot of added
>> FILE_OPEN_NO_RECALL bits and a couple of added attribute checks for
>> being offline to allow skipping some code.
>>
>> I think I'll push this change in a bit so we get a test release out
>> so people using OneDrive can test.
> I pushed this change as well as a followup change to make sure we don't
> inadvertently recall an offline file.  I also added handling for the
> Pinned and Unpinned attributes to chattr(1) and lsattr(1).
>
> The full set of changes can be tested by installing the Cygwin test
> release 3.6.0-0.77.g06aa5a751682.
>
> Please give it a try.  If you encounter a situation which still results
> in recalling an offline file in a situation which doesn't qualify for
> it, please report.  We will have to analyze that situation further
> then.
>
>
> Thanks,
> Corinna

Thanks for doing this work so quickly. I'm not subscribed to this 
mailing list so I didn't see previous messages.

I will try to check this in Cygwin this weekend but should tell you that 
I'm not cygwin user and now found a report of another user claiming this 
only happens in MSys and not in Cygwin.

https://github.com/msys2/MSYS2-packages/issues/3049


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