Re: Announcing xorriso-0.3.6
Hi,
Joerg Schilling wrote:
> Neither ISO-9660 not Rock Ridge support ACLs or xattrs.
True. But SUSP allows to define own extension field
types in the System Use Area. See
ftp://ftp.ymi.com/pub/rockridge/susp112.ps
I did that in form of AAIP. See
http://www.libburnia-project.org/wiki/AAIP
mkisofs is invited to join that protocol.
Maybe after some due time, kernels will begin
to interpret it and show ACL and userspace
xattr.
For now, one needs keen extraction software,
like xorriso, in order to retrieve the info.
-------------------------------------------------------
For bystanders:
- ISO 9660 / ECMA-119 defines directory records which
contain a filename, a pointer to its data content,
some other attributes, and a System Use Area for
additional (small) payload.
The meaning of that payload is not specified.
- System Use Sharing Protocol (SUSP) defines a packet
format for that area, the System Use Fields. It also
defines some field types for announcing the presence
of extensions and for enlarging the payload space up
to the maximum size of an ISO image: 8 TB.
SUSP states that a reader program shall ignore any
fields of unknown type.
This rule is nearly 20 years old and even obeyed
by Solaris hsfs which seems not to have been adapted
to the newer specs since about 15 years.
- Rock Ridge Interchange Protocol (RRIP) is such an
extension. It adds the file attributes and file types
as expected by a POSIX (or rather X/Open) system.
- Arbitrary Attribute Interchange Protocol (AAIP) is
now another extension which is intended as companion
of RRIP.
Its field type AA allows to store a nearly arbitrary
number of value=name pairs. This is used by libisofs
to store ACL, xattr out of the "user" namespace,
and own management information in an "isofs" namespace.
E.g. "isofs.di" which records the original device
number and inode number of a file, allowing fast
incremental backup decisions.
---------------------------------------------------------
Have a nice day :)
Thomas
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