`exec` does not exit on EOF about multipass HOT 6 CLOSED

@simos, I took your advice and updated the upstream bug report with some more info including linking to this bug. I do think the libssh maintainers simply have not been active this week:)

from multipass.

After much debugging, I found this to be a bug in libssh.

In it's polling of stdin, it does not check if POLLHUP (which indicates EOF) is set on the fd. It's a very simple fix and I'll plan on proposing it in upstream libssh. In the meantime, we'll probably need to patch the version we are using.

from multipass.

BTW, here is the simple diff:

diff --git a/src/connector.c b/src/connector.c
index 54e85241..714ef815 100644
--- a/src/connector.c
+++ b/src/connector.c
@@ -368,7 +368,7 @@ static int ssh_connector_fd_cb(ssh_poll_handle p,
 
     if (revents & POLLERR) {
         ssh_connector_except(connector, fd);
-    } else if((revents & POLLIN) && fd == connector->in_fd) {
+    } else if(((revents & POLLIN) || (revents & POLLHUP)) && fd == connector->in_fd) {
         ssh_connector_fd_in_cb(connector);
     } else if((revents & POLLOUT) && fd == connector->out_fd) {
         ssh_connector_fd_out_cb(connector);

from multipass.

Here is the upstream bug report:

https://bugs.libssh.org/T81

from multipass.

Still no response from upstream. If we don't get a response soon, we should probably clone our own libssh branch, fix it, and point our submodule to it.

from multipass.

I think the bug report on libssh would need a bit of description to demonstrate the issue.

With plain SSH, the following works

$ echo bar | ssh localhost tee foo
bar
$ 

Perhaps a link to this report or a suitable example with plain SSH that demonstrates the issue?

from multipass.