Allow renaming paths as they are restored

[Michael Terry]

= Background =

Deja Dup has this feature where if you restore your backup as a different username, it will put your restored files in your current home directory. Which would be easy if the parent directory of the backup were $HOME. But it always backs up with a parent directory of / (to allow backing up non-home directories and the like).

So, Deja Dup restores everything to a /tmp directory, renames what it needs, then moves the files to their final destination. But this has caused several bugs with available space in /tmp.

= Feature Request =

So it would be nice if Deja Dup could just pass --rename='|home/foo|home/bar|' to duplicity and be done. Duplicity would redirect any incoming files to home/foo to similar named files under home/bar.

= Design =

I think a decent syntax would be to follow sed's example and allow a leading separator character, the input match, a separator, the output result, and a final separator. An error would occur if it couldn't be parsed.

To keep it simple, the string would be parsed as a literal string. That is, no globbing, no regular expressions. That would be over-engineering this, I think.

Each rename argument would be chained up. So the first rename would happen, then the second would run, etc.

In the case of a conflict (i.e. home/bar is already in the backup), a warning is printed, and duplicity ignores the rename. Better not to try to merge the two directories.

= Approval =

Ken, does the above make sense and desirable? I can start working on a patch.

[Peter Schuller (scode)]

FWIW I think it sounds like a definitely useful feature. One implementation complexity issue I see is that answering "is X in the backup" is not necessarily simple?

[Michael Terry (mterry)]

I just remembered that Deja Dup one day also wants to try to visually prompt for sudo rights if it can't restore a file (i.e. you backed up /usr/share or something but are running as a user). So Deja Dup may always want to restore to a /tmp directory first.

In that case, let me open a different bug about other possible ways to alleviate that problem. This feature could still be useful, and I'll leave it open. But I may not be in as much a hurry to implement it.

[Michael Terry (mterry)]

@Peter, I think it is... I think that's part of the signature file metadata. Not sure off the top of my head.

[Michael Terry (mterry)]

I'm looking at implementing this again. I decided I don't like the idea of a separator. It's just geeky and 99% of the time unneeded. Rather, it would be better to have the option take two arguments. But getopt can't handle that right now. However... optparse can. And it's a little more fully-featured. I'm looking into porting commandline.py to optparse.

[Kenneth Loafman (kenneth-loafman)]

Now that you've got optparse working, do you have time to revisit this issue?

[Michael Terry (mterry)]

Hey, man, I already did! :) It's in 0.6 and 0.7 branches. The --rename argument. Deja Dup is anxiously awaiting 0.6.07's release to use it.

[Kenneth Loafman (kenneth-loafman)]

Fantastic :-) 0.6.07 will be out by the 28th.