[Dev] How to share files with Cynara

Jussi Laako jussi.laako at linux.intel.com
Mon May 5 08:44:27 GMT 2014

On 2.5.2014 1:20, Schaufler, Casey wrote:
>> + data shared between group of users
> Sorry, but I have never seen this as a requirement.

I don't know if it is written down somewhere, but it is very common type 
of sharing case.

At bare minimum, to me, it would make sense to differentiate at least 
between occasional "guest" users and normal "privileged" users of the 
system who have real user account.

>> So we need at leas one overall "Public" folder in the system.
> Which is a *direct* violation of the application isolation requirement.

If you can for example download PDF and open it in a PDF reader 
application you already violate the application isolation. This is no 
different. When I download a PDF document on Android, it asks me if I 
want to open it in Acrobat Reader or some other reader capable of 
handling PDFs.

It is very common use case that you would like to share a photo or 
similar file with other users of the system. Having to upload it to 
cloud service like OneDrive or DropBox to allow sharing it is just 
additional annoyance for the end user. And from "application isolation" 
point of view there's no difference. It's the same file, regardless if 
you load it from local storage or from a web URL.

>> You could create
>> a group called "Family" with gumd and assign family members to it and then
>> share for example family vacation photos in that folder.
> You could, but what requirement are you addressing?

Common sense requirement... ;)

We don't have any detailed requirements for multi-user while multi-user 
support in itself brings up number of new use cases and likely necessary 
requirements such as ability to share files between multiple users of 
the same system.

I know only about 20 high level "hands waving" requirements for 
multi-user and that's all.

>> This is why I'm advocating "group home" folders, for example
>> /home/groups/Family with root:Family 770 permissions.
> This *is not* a general purpose Linux system. Unless there is a
> requirement that we have a mechanism to do this there is no
> reason to worry about it, and good reasons not to.

I'm just trying to think about usability from normal users' point of view.

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