Re: Handling APFS/HFS+

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On 02/06/2020 10:38, DiagonalArg wrote:
> ---- On Mon, 01 Jun 2020 12:07:37 -0700 Denis Corbin 
> <[email protected]> wrote ----
> 

[...]

> 
>>> Could I extract the particular files that may be giving me 
>>> trouble when I try to restore them to the linux FS and save
>>> them to a separate dar archive for later handling, without
>>> losing any data?
>> 
>> if you have cannot restore a file and want to keep as much 
>> information of it in a separated archive, you should use the 
>> filtering feature (see merging feature) that let you create an 
>> archive from a subset of a bigger one. This is done without 
>> restoring the files/directories so you do not depend on the 
>> operating system to support all data and meta-data associated to 
>> that file(s).
> 
> Ok, so one of the things I can do with a dar archive containing
> HFS+ files, but which I am manipulating on linux, is restore the
> files that are not producing errors, but create a new, smaller,
> archive containing only the problematic files.

you don't need to restore, you'd even better not restoring to preserve
at much properties as possible for files that have HFS+ attributes you
want to manipulate under linux... the filtering/merging operation has
the advantage not to go through local file system, just manipulating
data/metadata of one or two archive(s) into a new one while also
filtering out the file you don't want to retain.

[...]

> 
> But, can I look at the EA's that are not being extracted
> (failing), in order to see what they are?

Dar should list you the EA that failed to be restored. You can also
see the list of EA attached to a file using the -alist-ea option while
listing an archive.

> 
> What of a file that has a non-trivial resource fork?  Is there any 
> way for me to look in that fork?  Can I extract it from the
> archive in some form and dig around in it?

Nop, you can just see the name of attributes but not the contents of
forks, exactly the same as data of plain file.

> 
> Similar question for any other piece of data that is failing to 
> restore.

dar will try to restore the different part of a file/directory, but if
some parts fail (data, attributes, meta-data...) it will just report
the failure and the reason of the failure. No, dar will never restore
and even not try to restore a failed item into something else, this
would just be a non-sense in regard of the purpose of this tool.

However, you have several tools that let you access an existing dar
archive as a read-only file system. I'm not sure whether you could
read all the attributes you expect, but you should give a try.

See dar_fuse and AVFS:
http://dar.linux.free.fr/doc/presentation.html#external_tools

[...]

Cheers,
Denis
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