Fix hang when dropping content needs to lock the content on a ssh remote,
which occurred when the remote has git-annex version 5.20151019 or newer.
Analysis: `race` runs 2 threads at once, and the hGetLine finishes first.
So, it tries to cancel the waitForProcess, but unfortunately that is making
a foreign call and so cannot be canceled. The remote git-annex-shell
is waiting for a line on stdin before it will exit. Deadlock.
This only occurred sometimes; I reproduced it going from darkstar to
elephant, but not from darkstar to darkstar. Not sure how that fits into
the above analysis -- perhaps a race condition is also involved?
Fixed by not using `race`; now the hGetLine will fail with an exception
if the remote git-annex-shell exits without any output.
Made all Annex.Perms file mode changing functions ignore errors when
core.sharedRepository is set, because the file might be owned by someone
else. I don't fancy getting bug reports about crashes due to set modes in
this configuration, which is a very foot-shooty configuration in the first
place.
The fsck warning is necessary because old repos kept files mode 444, which
doesn't allow locking them, and so if the mode remains 444 due to the file
being owned by someone else, the user should be told about it.
When annex.thin is set, adding an object will add the execute bits to the
work tree file, and this does mean that the annex object file ends up
executable.
This doesn't add any complexity that wasn't already present, because git
annex add of an executable file has always ingested it so that the annex
object ends up executable.
But, since an annex object file can be executable or not, when populating
an unlocked file from one, the executable bit is always added or removed
to match the mode of the pointer file.
Rationalle: User might have hook scripts whose output they want to see.
Also, git commit output may tell the user they forgot to add a file.
The output is not too ugly when there's nothing to commit.
Was using L.readFile, so the Handle would remain open until the garbage
collector got around to it. Changed to explicit open and close, so we know
it's always closed when the function returns.
This makes the direct mode to v6 upgrade able to be performed in one clone
of a repository without affecting other clones, which can continue using v5
and direct mode.
This does mean that it has to write out temp files containing updated
objects for the merge. So may use more disk space, and disk IO, but that
should generally win out over needing to launch N separate
git hash-object processes.
An unlocked present file does not have a pointer file in the worktree, so
info skipped counting it.
It may be that unused was also affected by the problem, but it seemed not
to be in my tests. I think because of the use of the associatedFilesFilter.
This fix slows down both info and unused a little bit, since they have to
query the contents of files from git, but only when handling unlocked files.
This fixes behavior in this situation:
l1 <- lockShared Nothing "lck"
l2 <- lockShared Nothing "lck"
dropLock l1
dropLock l2
Before, the lock was dropped upon the second dropLock call, but the fd
remained open, and would never be closed while the program was running.
Fixed by a rather round-about method, but it should work well enough.
It would have been simpler to open open the shared lock once, and not open
it again in the second call to lockShared. But, that's difficult to do
atomically.
This also affects Windows and PID locks, not just posix locks.
In the case of pid locks, multiple calls to waitLock within the same
process are allowed because the side lock is locked using a posix lock,
and so multiple exclusive locks can be taken in the same process. So,
this change fixes a similar problem with pid locks.
l1 <- waitLock (Seconds 1) "lck"
l2 <- waitLock (Seconds 1) "lck"
dropLock l1
dropLock l2
Here the l2 side lock fd remained open but not locked,
although the pid lock file was removed. After this change, the second
dropLock will close both fds to the side lock, and delete the pidlock.
