[Sugar-devel] Journal-like activities (was: Re: [ASLO] Release Read ETexts-19)

[James Simmons]

Sascha,

No need to apologize for a long email; this is interesting.  I'm
thinking I'll start working on an improved version of Gabriel's Leer
Pen Drive and see where that takes me.  I like the idea of the Journal
very much, but the implementation of the Journal Activity (if it's
correct to call it that) is not what I would like it to be.

James Simmons


On Thu, Mar 18, 2010 at 8:09 AM, Sascha Silbe
<sascha-ml-ui-sugar-devel at silbe.org> wrote:
> On Wed, Mar 17, 2010 at 05:08:08PM -0500, James Simmons wrote:
>
>> I was looking at the code for Leer Pen Drive and thinking how I could
>> improve on it, and in the process I ended up looking at
>> git.sugarlabs.org at the code for Journal.  Apparently that is not the
>> most recent code,
>
> I guess you were looking at the "journal" project (don't have internet
> access right now, so cannot check the exact name). That's indeed rather old
> code; the Journal has been integrated into the sugar package.
>
>> That wouldn't be too surprising except that the Journal Activity can write
>> to a USB or thumb drive.  I couldn't figure out how or even where it was
>> doing it, [...]
>
> The "journal" project is part of 0.82. Back then the data store handled
> removable media.
> In 0.84+, the data store was rewritten from scratch [1] and only handles the
> on-disk, native Sugar objects. Handling of "traditional" (POSIX) file
> storage (USB sticks, hard disks, etc.) has been moved into the Journal.
> The code you're looking for is sugar/src/jarabe/journal/model.py. In there,
> the classes DatastoreResultSet and InplaceResultSet form an abstraction
> layer over the data store and mounted (POSIX) file systems.
>
>> but it does seem that you could write an Activity that does everything the
>> Journal does, from writing to mounted media to unmounting it.
>
> Almost everything the Journal does can be done in an activity as well. It
> all boils down to permissions; usually the permissions are based on security
> considerations.
> The following actions are implemented (source references are for 0.88):
>
> - show item in Journal (D-Bus API)
>   - sugar/src/jarabe/journal/journalactivity.py
>   - D-Bus doesn't allow a second process with the same service name, so not
> overridable
>
> - show object picker (D-Bus API)
>   - sugar/src/jarabe/journal/journalactivity.py
>   - again, D-Bus prevents activities from providing this
>
> - mounting/unmounting file systems (e.g. USB sticks)
>   - show new mount points: sugar/src/jarabe/journal/volumestoolbar.py
>   - unmounting: sugar/src/jarabe/view/palettes.py:VolumePalette
>   - mounting (Frame, not Journal): sugar/extensions/deviceicon/volume.py
>   - without Rainbow:
>     - activities are able to mount and umount file systems using gio (resp.
> gvfs for older systems)
>   - with Rainbow:
>     - gio/gvfs probably refuses to unmount file systems mounted by the Frame
> from within activities (because the user ids are different)
>
> - browsing data store / file systems, reading all entries / files
>   - sugar/src/jarabe/journal/model.py
>   - without Rainbow:
>     - unrestricted
>   - with Rainbow:
>     - currently:
>       - data store access unrestricted
>       - file system access prevented by gio/gvfs permission settings
>     - future:
>       - see P_DOCUMENT / P_DOCUMENT_RO Bitfrost [2] protections
>
> - reading a single data store entry / file via Object Picker
>   - sugar-toolkit/src/sugar/graphics/objectchooser.py
>   - unrestricted
>
> - writing a single data store entry / file (acquired via Object Picker)
>   - without Rainbow:
>     - unrestricted
>   - with Rainbow:
>     - currently:
>       - data store access unrestricted
>       - file system access prevented by gio/gvfs permission settings
>     - future
>       - unrestricted
>
> - writing random data store entries / files
>   - without Rainbow:
>     - unrestricted
>   - with Rainbow:
>     - currently:
>       - data store access unrestricted
>       - file system access prevented by gio/gvfs permission settings
>     - future
>       - subject to P_DOCUMENT Bitfrost [2] protection
>
>
> Bitfrost protections can be disabled, see the Bitfrost specs [2] for
> details.
>
> Sorry for the long mail; it's not just an answer to your questions but also
> a Rainbow TODO list. :)
>
>
> [1] http://wiki.sugarlabs.org/go/Development_Team/Datastore_Rewrite
> [2] http://dev.laptop.org/git/security/tree/bitfrost.txt
>
> CU Sascha
>
> --
> http://sascha.silbe.org/
> http://www.infra-silbe.de/
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