What kind of error is 13?

[Axel Kittenberger]

I never figured out how I should tread error 13 from rsync, "Problem
with diagnostics". My question is, is this a transient or permanent
error? Or how seriously did something go wrong when rsync returns 13?
I don't get much smarter reading the rsync source either.

For reference this is for Lsyncd, which watches files with inotify and
uses rsync to transmit changes to a slave. It compacts calls to rsync
with filters so rsync has only to look at the files that changed etc:

Here is the table of its exitcode:

local rsync_exitcodes = {
       [  0] = "ok",
       [  1] = "die",
       [  2] = "die",
       [  3] = "again",
       [  4] = "die",
       [  5] = "again",
       [  6] = "again",
       [ 10] = "again",
       [ 11] = "again",
       [ 12] = "again",
       [ 13] = ???,
       [ 14] = "again",
       [ 20] = "again",
       [ 21] = "again",
       [ 22] = "again",
       [ 23] = "ok", -- partial transfers are ok, since Lsyncd has
registered the event that
       [ 24] = "ok", -- caused the transfer to be partial and will recall
rsync for that anyway.
       [ 25] = "die",
       [ 30] = "again",
       [ 35] = "again",
       [255] = "again", -- all kind of ssh-errors .
}

ok: changes have been transfered
again: transient error, keep recalling rsync until it works.
die: something is seriously amiss, die spectacular.

What should I put at 13?

If I understood the log code correctly: in cases it cannot assemble
the message, couldn't it just return the partial message string and
the correct error number?