AF_UNIX and AF_VSOCK listen sockets can be passed in by systemd on
startup. This allows systemd to manage the listen socket until the
first client connects and between restarts. Advantages of socket
activation are that parallel startup of network services becomes
possible and that unused daemons do not consume memory.
The key to achieving this is the LISTEN_FDS environment variable, which
is a stable ABI as shown here:
https://www.freedesktop.org/wiki/Software/systemd/InterfacePortabilityAndStabilityChart/
We could link against libsystemd and use sd_listen_fds(3) but it's easy
to implement the tiny LISTEN_FDS ABI so that qemu-ga does not depend on
libsystemd. Some systems may not have systemd installed and wish to
avoid the dependency. Other init systems or socket activation servers
may implement the same ABI without systemd involvement.
Test as follows:
$ cat ~/.config/systemd/user/qga.service
[Unit]
Description=qga
[Service]
WorkingDirectory=/tmp
ExecStart=/path/to/qemu-ga --logfile=/tmp/qga.log --pidfile=/tmp/qga.pid --statedir=/tmp
$ cat ~/.config/systemd/user/qga.socket
[Socket]
ListenStream=/tmp/qga.sock
[Install]
WantedBy=default.target
$ systemctl --user daemon-reload
$ systemctl --user start qga.socket
$ nc -U /tmp/qga.sock
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Add AF_VSOCK (virtio-vsock) support as an alternative to virtio-serial.
$ qemu-system-x86_64 -device vhost-vsock-pci,guest-cid=3 ...
(guest)# qemu-ga -m vsock-listen -p 3:1234
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Remove glib.h includes, as it is provided by osdep.h.
This commit was created with scripts/clean-includes.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This is mostly in preparation for the win32 port, which won't use
GIO channels for reasons that will be made clearer later. Here the
GAChannel class is just a loose wrapper around GIOChannel
calls/callbacks, but we also roll in the logic/configuration for
various channel types and managing unix socket connections, which makes
the abstraction much more complete and further aids in the win32 port
since isa-serial/unix-listen will not be supported initially.
There's also a bit of refactoring in the main logic to consolidate the
exit paths so we can do common cleanup for things like pid files, which
weren't always cleaned up previously.
Stefan Hajnoczi
Peter Maydell
Michael Roth