Re: [rdiff-backup-users] Re: [librsync-devel] librsync: ERROR: (rs_file_copy_cb) seek failed: Invalid argument

[Ben Escoto]

On Thu, 06 Nov 2003 15:39:50 -0700
Robert Weber <address@hidden> wrote:
> It Failed:
...
> rdiff_backup.librsync.librsyncError: librsync error 100 while in patch
> cycle
> 
> But to be absolutely sure, I re-ran the rdiff, but on the original file in
> on the client(rather than copying it to the server first) and lo and
> behold:
...
> librsync: ERROR: (rs_file_copy_cb) seek failed: Invalid argument
> librsync: ERROR: (rs_job_complete) patch job failed: IO error
...
> 1) why does rdiff-backup try to diff-patch a file that is the the same on
> the mirror as it is remotely

Probably rdiff-backup thinks the metadata of the file have changed.
Internally, rdiff-backup uses "diffs" and "patches" at a higher level,
where they include both data and metadata.  So a change in either will
produce a diff with both.

It's inefficient, but rdiff-backup doesn't know whether or not a file
has changed.  It doesn't compute an SHA hash or anything like that
separately from librsync.

So if you make a file, run rdiff-backup, change the perms of the file,
and run it again, you'll see a .diff.gz increment in the
rdiff-backup-data directory.  This stores the old permission
information.  Here it isn't really necessary to have any regular data
associated with that file, but the system does avoid special cases.

> 2) how should librsync behave when it patches a file that matches the
> original?

Presumably when asked to produce a delta for such a situation, a very
small "null" delta should be created, that says not to replace any
blocks.  Patching with the null delta should produce the original
basis file.


-- 
Ben Escoto

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