613e747d91
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.
48 lines
2.2 KiB
Markdown
48 lines
2.2 KiB
Markdown
For the record, there is a slight weirdness with how git-annex
|
|
handles a signal like ctrl-c.
|
|
|
|
For example:
|
|
|
|
joey@gnu:~/tmp/b>git annex copy a b --to origin
|
|
copy a (checking origin...) (to origin...)
|
|
SHA256-s104857600--20492a4d0d84f8beb1767f6616229f85d44c2827b64bdbfb260ee12fa1109e0e
|
|
3272 0% 0.00kB/s 0:00:00 ^C
|
|
zsh: interrupt git annex copy a --to origin
|
|
joey@gnu:~/tmp/b>
|
|
rsync error: unexplained error (code 130) at rsync.c(549) [sender=3.0.9]
|
|
|
|
Here git-annex exits before rsync has fully exited. Not a large problem
|
|
but sorta weird.
|
|
|
|
The culprit is `CmdLine.startup` in Utility.SafeCommand, which installs
|
|
a default signal handler for SIGINT, which causes it to immediatly
|
|
terminate git-annex. rsync, in turn, has its own SIGINT handler, which
|
|
prints the message, typically later.
|
|
|
|
(Why it prints that message and not its more usual message about having
|
|
received a signal, I'm not sure?)
|
|
|
|
It's more usual for a `system` like thing to block SIGINT, letting the child
|
|
catch it and exit, and then detecting the child's exit status and terminating.
|
|
However, since rsync *is* trapping SIGINT, and exiting nonzero explicitly,
|
|
git-annex can't tell that rsync failed due to a SIGINT by examining the
|
|
`waitpid` result.
|
|
And, git-annex typically doesn't stop when a single child fails. In the
|
|
example above, it would go on to copy `b` after a ctrl-c!
|
|
|
|
A further complication is that git-annex is itself a child process
|
|
of git, which does not block SIGINT either. So if git-annex blocks SIGINT,
|
|
it will be left running in the background after git exits, and continuing
|
|
with further actions too. (Perhaps its SIGINT handling is a bug in git.)
|
|
|
|
Now, rsync does have a documented exit code it uses after a SIGINT.
|
|
But other programs git-annex runs generally do not. So it would be possible
|
|
to special case in support for rsync, blocking SIGINT while running it,
|
|
noticing it exited with 20, and git-annex then stopping. But this is
|
|
ugly and failure prone if rsync's code 20 changes. And it only
|
|
would fix the rsync case, not helping with other commands like wget, unless
|
|
it assumes they never trap SIGINT on their own.
|
|
|
|
Which is why the current behavior of not blocking SIGINT was chosen,
|
|
as a less bad alternative. Still, I'd like to find a better one.
|
|
--[[Joey]]
|