Re: [rdiff-backup-users] Feature Suggestions for Cross-Platform-Compatibility

[Andrew Ferguson]

On Oct 10, 2008, at 8:24 AM, Toscano2 wrote:
> - the appended timestamps (e.g. 'current_mirror. 
> 2008-10-07T16:43:00-07:00.data') are not compatible with
> Windows. It's impossible to simply copy over/rsync on an ext3- 
> filesystem locally rdiff-backupped data later to a Windows system  
> without breaking the backups. (Directly using rdiff-backup between  
> local Windows and remote Linux system cannot be used.)

- If you use rdiff-backup on both sides, then this problem won't be  
there. Rdiff-backup is now well-tested for avoiding reserved Windows  
characters (and other reserved Windows names).
- You could also add : to the chars-to-quote yourself (and,  
presumably, the other DOS reserved characters)
- You could write a patch for rsync which translates reserved Windows  
characters and names.

> So there should be an alternative commandline option (e.g. '--use- 
> windows-compatible-timestamps' or just '--use-compatible- 
> timestamps') which generates the timestamp without ':'/colons, e.g.:  
> '2007-07-28T10-51-18', since the W3-time/datestamps are not meant  
> for being used in filenames.

Patches fully compatible with existing rdiff-backup usage are welcome.

> - the timezone could be left out, if by convention, rdiff-backup would
> use/convert to UTC before writing timestamps to files, e.g. '--use- 
> utc' to maintain backward compatibility).So problems with daylight  
> saving time and managing servers across different timezones are  
> resolved.

I believe you can override this by adjusting the TZ variable for just  
the rdiff-backup process. e.g.,

TZ=UTC rdiff-backup ....

Let me know if that doesn't work (and you are using Python 2.3 or  
later), as it would be a bug in rdiff-backup.

> - an option like '--preserve-case' to explicitely override auto- 
> detected settings if any case-insensitive filesystem is used (NOT  
> via '--override-chars-to-quote').

What's wrong with --override-chars-to-quote ?    Really, I don't  
understand why people want to do this on case-insensitive filesystems  
-- I view dataloss as infinitely more drastic than cosmetic issues  
with filenames. rdiff-backup reverses the translation during a restore.

> The last two ideas would keep filenames smaller, in many cases  
> prevent filepaths from violating length-constraints.

On Unix, rdiff-backup has proper support for handling too-long  
filenames. I see there was an email recently about this not working on  
Windows, a bug I'll try to look into after the next release.

> - finally, something as '--override-chars-to-quote-from-file' would  
> be useful, so any non-printable characters/ranges can be specified  
> here, too.
> This would ease creating a single compatibility-file for e.g. easy  
> Windows-Linux-Mac migration, similar to the '--include-from-file'  
> options.

--override-chars-to-quote is a regular expression, so you can put non- 
printable characters in by escaping them (octal) ... eg:

--override-chars-to-quote "\000-\037"

will make sure that ASCII characters 0 - 31 are escaped. If you write  
a wrapper script to rdiff-backup, you can put in non-printable  
characters directly.

I would certainly consider a patch to add an --override-chars-to-quote- 
from-file option, and it might be a good first patch for someone new  
to Python or the rdiff-backup code. The get_ctq_from_fsas() function  
in fs_abilities.py shows how rdiff-backup figures out which chars  
should be quoted.



Andrew