In general, git-annex does not try to preserve file permissions. For
example, they don't round trip through special remotes. So it's ok to not
preserve them for git remotes either.
On crippled filesystems, rsync has been observed failing after the file
was transferred because it couldn't set some permission or other.
When rsyncProgress pipes rsync's stdout, this turns out to cause a ssh
process started by rsync to be left behind as a zombie. I don't know why,
but my recent zombie reaping cleanup was correct, it's just that this other
zombie, that's not directly started by git-annex, was no longer reaped
due to changes in the cleanup. Make rsyncProgress reap the zombie started
by rsync, as a workaround.
FWIW, the process tree looks like this. It seems like the rsync child
is for some reason starting but not waiting on this extra ssh process.
Ssh connection caching may be involved -- disabling it seemed to change
the shape of the tree, but did not eliminate the zombie.
9378 pts/14 S+ 0:00 | \_ rsync -p --progress --inplace -4 -e 'ssh' '-S' ...
9379 pts/14 S+ 0:00 | | \_ ssh ...
9380 pts/14 S+ 0:00 | | \_ rsync -p --progress --inplace -4 -e 'ssh' '-S' ...
9381 pts/14 Z+ 0:00 | \_ [ssh] <defunct>
This seems to fix a problem I've recently seen where ctrl-c during rsync
leads to `git annex get` moving on to the next thing rather than exiting.
Seems likely that started happening with the switch to System.Process
(d1da9cf221), as the old code took care
to install a default SIGINT handler.
Note that since the bug was only occurring sometimes, I am not 100% sure
I've squashed it, although I seem to have.
Current implementation parses rsync's output a character a time, which
is hardly efficient. It could be sped up a lot by using hGetBufSome,
but that would require going really lowlevel, down to raw C style buffers
(good example of that here: http://users.aber.ac.uk/afc/stricthaskell.html)
But rsync doesn't output very much, so currently it seems ok.
