Re: ls/stat on OneDrive causes download of files

[Brian Inglis <Brian.Inglis@SystematicSW.ab.ca>]

On 2024-03-06 06:28, Corinna Vinschen via Cygwin wrote:
> On Mar  6 14:22, Corinna Vinschen via Cygwin wrote:
>> On Mar  5 19:54, Marcin Wisnicki via Cygwin wrote:
>>> If I invoke ls or anything else that does stat inside OneDrive folder
>>> it will trigger download of all files.
>>>
>>> OneDrive uses placeholder files[1] to represent remote files.
>>>
>>> I'm guessing reading file content in stat is to support detection of
>>> actually executable files as in here[2]?
>>>
>>> I think this should be disabled on non-hydrated placeholder files.
>>> Running `find` or 'ls -R` and having your entire OneDrive downloaded
>>> is extremely problematic.
>>>
>>> I could live without executable scripts in the OneDrive folder and
>>> it's easy to mark files as always offline to solve it.
>>>
>>> Another idea is to skip checking files with extensions known to be
>>> non-executable such as jpg (or just any extensions that is not known
>>> to be executable).
>>
>> Nothing of this makes sense from a POSIX library POV.  The library can
>> either not handle placeholder files specially, as today, or it can
>> handle them all the same way.
>>
>> Given these placeholder files are actually reparse points of type
>> IO_REPARSE_TAG_FILE_PLACEHOLDER, we can handle them as symbolic links.
>>
>> However, the structure of the IO_REPARSE_TAG_FILE_PLACEHOLDER reparse
>> data buffer is undocumented.  It would be helpful if somebody using
>> OneDrive would examine the content of the attached REPARSE_DATA_BUFFER.
>>
>>> [2] https://github.com/msys2/msys2-runtime/blob/msys2-3.4.10/winsup/cygwin/fhandler/disk_file.cc#L548
>>
>> The NtReadFile call at this point is not the problem.  It would be
>> helpful to point to Cygwin's source instead of MSYS2, btw.
> 
> Oh, btw., this is from
> https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/c8e77b37-3909-4fe6-a4ea-2b9d423b1ee4:
> 
>    IO_REPARSE_TAG_FILE_PLACEHOLDER
>    0x80000015
> 
>      Obsolete.
>      ---------
>      Used by Windows Shell for legacy placeholder files in Windows 8.1.
>      Server-side interpretation only, not meaningful over the wire.
> 
> So even if we support them, what is their replacement in W10 and later?

May or not help:

https://stackoverflow.com/questions/59152220/cant-get-reparse-point-information-for-the-onedrive-folder
-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry