(this discussion has been moved into its own-thread to get it back on-topic)
Matthew Toseland wrote:
> How are you handling committing a directory?
Hehe, I lost a bit of sleep thinking through that one :)
What I've come up with is 4 'pseudo-files' that live in the toplevel
directory of a freedisk:
- .status - readonly, when read returns a status keyword, one of:
- 'idle' - neither updating nor committing
- 'committing' - dusk is syncing back into freenet
- 'updating' - disk is syncing locally from freenet
- 'failed\n<more details>' - something fatal happened
- .publickey - read/write - write an SSK public key into this file to
link the local freedisk with an in-freenet directory, so the
directory can be mounted readonly
- .privatekey - read/write - write an SSK private key into this file to
link the local freedisk with an in-freenet directory, so the
directory can be mounted read/write
- .cmd - write-only - typically one-word commands will be written in,
such as 'commit' or 'update'
While committing or updating, the directory tree will be readonly,
despite any permissions to the contrary.
When a freedisk is 'update'd from freenet, only the nodes
(file/directory records) will be fetched, not the data. When/if an
individual file is opened in read, update or append mode, the file's
data will be fetched as a CHK from freenet. If a file is opened in
write-only mode (ie truncate), no freenet fetch will occur, since the
file will become a new CHK with no reference to past content.
When files are locally written, the changes will reside only in memory
until the next commit.
I'm working on a command-line utility called 'freedisk' which handles
all the pseudo-files' I/O in a simple front-end, for example:
freedisk -m /mnt/freenet new fred
Create a new freedisk called 'fred', at /mnt/freenet/usr/fred,
mounted readonly, with new random pub/priv keys
freedisk -m /mnt/freenet add foo SSK at yadayadayada
Import a freedisk and mount readonlly, at /mnt/freenet/usr/foo
freedisk -m /mnt/freenet update foo
Update freedisk 'foo' (at /mnt/freenet/usr/foo') from freenet
freedisk -m /mnt/freenet add bar SSK at yadayada private
Import a freedisk and mount read/write, at /mnt/freenet/usr/bar,
using SSK private key SSK at yadayada
freedisk -m /mnt/freenet commit bar
Commit directory /mnt/freenet/usr/bar back into freenet
If the environment variable 'FREEDISK_MOUNTPOINT' is set, then the
'-m /mnt/freenet' option becomes unnecessary.
Whenever a file's contents are fetched from freenet, it will be cached
in memory, not on disk - this is for security reasons, since if a PC is
uplifted by an attacker, a hard disk analysis won't identify anyone as
having accessed a freedisk (as long as they have an encrypted swapfile,
that is!)
In the xml directory file discussed below, the 'hash' attribute will be
hexadecimal SHA(1) of the file's contents. (Not base64, because of the
plurality of base64 alphabets).
>> To be honest, my gut feeling is that it's best for the 'freedisk'
>> project if I implement my own manifest scheme. The idea would be:
>>
>> - a manifest key, inserted as a single 'text/xml' file into
>> USK at blahblahblah/name/n, and of the form:
>>
>> <freedisk name="diskname" owner="nick">
>> <node path="/"/>
>> <node path="/chinese_democracy.doc"
>> hash="yadayada"
>> size="nnn"
>> mimetype="application/msword"
>> uri="CHK at yadayadayada"
>> />
>> ...
>> </freedisk>
>>
>> - CHKs for each file node
Cheers
David
