[Samba] How to read NTFS ADS (alternate data steams) using libsmbclient?

[Jeremy Allison]

On Sun, Nov 15, 2020 at 09:48:03AM +0000, Rowland penny via samba wrote:
>On 15/11/2020 09:00, 赵晶 via samba wrote:
>>Hi Samba team,
>>
>>We have a Windows SMB share which contains some files with ADS (alternate
>>data streams). In our client C/C++ code that runs on a Linux client, we
>>want to retrieve the list of ADS of a file and download all the streams,
>>similar to what is provided by smbclient's interactive session (allinfo,
>>get).
>>
>>But as we evaluate libsmbclient (as we'd like to do above in code), we
>>don't find any such API w.r.t ADS. The closest is an API to get extended
>>attributes, which is not ADS.
>>
>>http://mrs.suzu841.com/dox/samba_doxygen/group__libsmbclient.html
>>
>>Is there a way to query/read data streams using libsmbclient? Any
>>suggestion is welcome.
>>
>>Thanks,
>>Jing
>
>You might want to look at the code for 'vfs_streams_xattr', not sure 
>if this will help, but it is probably the nearest Samba has to what 
>you are asking.

Actually, that's server-side code, not client.

The interface needed for this is in the libcli interface. The
call you'd need is: cli_qpathinfo_streams().

libsmbclient uses this interface internally, but the problem
is it's not exposed as an external stable ABI (we make changes
often at the cli_XXX() layer often so we don't consider this
a publised ABI).

smbclient can get this information via the 'allinfo pathname'
command. Can you shell script that and use output from there ?