Add an implementation for send_fd_scm to the async QMP implementation.
Like socket_scm_helper mentions, a non-empty payload is required for
QEMU to process the ancillary data. A space is most useful because it
does not disturb the parsing of subsequent JSON objects.

A note on "voiding the warranty":

Python 3.11 removes support for calling sendmsg directly from a
transport's socket. There is no other interface for doing this, our use
case is, I suspect, "quite unique".

As far as I can tell, this is safe to do -- send_fd_scm is a synchronous
function and we can be guaranteed that the async coroutines will *not* be
running when it is invoked. In testing, it works correctly.

I investigated quite thoroughly the possibility of creating my own
asyncio Transport (The class that ultimately manages the raw socket
object) so that I could manage the socket myself, but this is so wildly
invasive and unportable I scrapped the idea. It would involve a lot of
copy-pasting of various python utilities and classes just to re-create
the same infrastructure, and for extremely little benefit. Nah.

Just boldly void the warranty instead, while I try to follow up on
https://bugs.python.org/issue43232



Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210923004938.3999963-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

This serves two purposes:

(1) It is now possible to discern whether or not clear() removed any
event(s) from the queue with absolute certainty, and

(2) It is now very easy to get a List of all pending events in one
chunk, which is useful for the sync bridge.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210923004938.3999963-4-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Synchronous clients may want to know if they're about to block waiting
for an event or not. A method such as this is necessary to implement a
compatible interface for the old QEMUMonitorProtocol using the new async
internals.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210923004938.3999963-3-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Expose the greeting as a read-only property of QMPClient so it can be
retrieved at-will.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210923004938.3999963-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Add syntax highlighting for the incoming and outgoing QMP messages.
This is achieved using the pygments module which was added in a
previous commit.

The current implementation is a really simple one which doesn't
allow for any configuration. In future this has to be improved
to allow for easier theme config using an external config of
some sort.

Signed-off-by: G S Niteesh Babu <niteesh.gs@gmail.com>
Message-Id: <20210823220746.28295-6-niteesh.gs@gmail.com>
Signed-off-by: John Snow <jsnow@redhat.com>

Added pygments as optional dependency for AQMP TUI.
This is required for the upcoming syntax highlighting feature
in AQMP TUI.
The dependency has also been added in the devel optional group.

Added mypy 'ignore_missing_imports' for pygments since it does
not have any type stubs.

Signed-off-by: G S Niteesh Babu <niteesh.gs@gmail.com>
Message-Id: <20210823220746.28295-5-niteesh.gs@gmail.com>
Signed-off-by: John Snow <jsnow@redhat.com>

Add an entry point for aqmp-tui. This will allow it to be run from
the command line using "aqmp-tui localhost:1234"
More options available in the TUI can be found using "aqmp-tui -h"

Signed-off-by: G S Niteesh Babu <niteesh.gs@gmail.com>
Message-Id: <20210823220746.28295-4-niteesh.gs@gmail.com>
Signed-off-by: John Snow <jsnow@redhat.com>

Added AQMP TUI.

Implements the follwing basic features:
1) Command transmission/reception.
2) Shows events asynchronously.
3) Shows server status in the bottom status bar.
4) Automatic retries on disconnects and error conditions.

Also added type annotations and necessary pylint/mypy configurations.

Signed-off-by: G S Niteesh Babu <niteesh.gs@gmail.com>
Message-Id: <20210823220746.28295-3-niteesh.gs@gmail.com>
Signed-off-by: John Snow <jsnow@redhat.com>

Added dependencies for the upcoming AQMP TUI under the optional
'tui' group.

The same dependencies have also been added under the devel group
since no work around has been found for optional groups to imply
other optional groups.

Signed-off-by: G S Niteesh Babu <niteesh.gs@gmail.com>
Message-Id: <20210823220746.28295-2-niteesh.gs@gmail.com>
Signed-off-by: John Snow <jsnow@redhat.com>

I'm not exposing this via the Makefile help, it's not likely to be
useful to passersby. Switch the avocado runner to the 'legacy' runner
for now, as the new runner seems to obscure coverage reports, again.

Usage is to enter your venv of choice and then:
`make check-coverage && xdg-open htmlcov/index.html`.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-28-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Tests a real connect, a real accept, and really sending and receiving a
message over a UNIX socket.

Brings coverage of protocol.py up to ~93%.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-27-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

This tests most of protocol.py -- From a hacked up Coverage.py run, it's
at about 86%. There's a few error cases that aren't very well tested
yet, they're hard to induce artificially so far. I'm working on it.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-26-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Avocado v90 includes improved support for running async unit tests. The
workaround that existed prior to v90 causes the unit tests to fail
afterwards, however, so upgrade our minimum version pin to the very
latest and greatest.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-25-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Add a warning whenever AQMP is used to steer people gently away from
using it for the time-being.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-24-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

As a convenience. It isn't used by the library itself, but it is used by
the test suite. It will also come in handy for users of the library
still on Python 3.6.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-23-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

This is added in anticipation of wanting it for a synchronous wrapper
for the iotest interface. Normally, execute() and execute_msg() both
raise QMP errors in the form of Python exceptions.

Many iotests expect the entire reply as-is. To reduce churn there, add a
private execution interface that will ease transition churn. However, I
do not wish to encourage its use, so it will remain a private interface.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-22-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Add execute() and execute_msg().

_execute() is split into _issue() and _reply() halves so that
hypothetical subclasses of QMP that want to support different execution
paradigms can do so.

I anticipate a synchronous interface may have need of separating the
send/reply phases. However, I do not wish to expose that interface here
and want to actively discourage it, so they remain private interfaces.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-21-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Add the ability to handle and route messages in qmp_protocol.py. The
interface for actually sending anything still isn't added until next
commit.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-20-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

mypy handles this better -- but we only need the workaround because
pylint under Python 3.6 does not understand that a MutableMapping really
does have a .get() method attached.

We could remove this again once 3.7 is our minimum.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-19-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

The star of our show!

Add most of the QMP protocol, sans support for actually executing
commands. No problem, that happens in the next several commits.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-18-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

too-many-function-args seems prone to failure when considering
things like Method Resolution Order, which mypy gets correct. When
dealing with multiple inheritance, pylint doesn't seem to understand
which method will actually get called, while mypy does.

Remove the less powerful, redundant check.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-17-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

This class was designed as a "mix-in" primarily so that the feature
could be given its own treatment in its own python module.

It gets quite a bit too long otherwise.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-16-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

The QMP spec doesn't define very many objects that are iron-clad in
their format, but there are a few. This module makes it trivial to
validate them without relying on an external third-party library.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-15-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

The Message class is here primarily to serve as a solid type to use for
mypy static typing for unambiguous annotation and documentation.

We can also stuff JSON serialization and deserialization into this class
itself so it can be re-used even outside this infrastructure.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-14-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

This is added as a courtesy: many protocols are line-based, including
QMP. Putting it in AsyncProtocol lets us keep the QMP class
implementation just a pinch more abstract.

(And, if we decide to add a QTEST implementation later, it will need
this, too. (Yes, I have a QTEST implementation.))

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-13-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Add hooks designed to log/filter incoming/outgoing messages. The primary
intent for these is to be able to support iotests which may want to log
messages with specific filters for reproducible output.

Another use is for plugging into Urwid frameworks; all messages in/out
can be automatically added to a rendering list for the purposes of a
qmp-shell like tool.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-12-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

QMP can transmit some pretty big messages, and the default limit of 64KB
isn't sufficient. Make sure that we can configure it.

Reported-by: G S Niteesh Babu <niteesh.gs@gmail.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-11-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

It's a little messier than connect, because it wasn't designed to accept
*precisely one* connection. Such is life.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-10-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Give the connection and the reader/writer tasks nicknames, and add
logging statements throughout.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-9-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-8-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

This serves a few purposes:

1. Protect interfaces when it's not safe to call them (via @require)

2. Add an interface by which an async client can determine if the state
has changed, for the purposes of connection management.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-7-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

This is the bare minimum that you need to establish a full-duplex async
message-based protocol with Python's asyncio.

The features to be added in forthcoming commits are:

- Runstate tracking
- Logging
- Support for incoming connections via accept()
- _cb_outbound, _cb_inbound message hooks
- _readline() method

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-6-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Python 3.6 does not have all of the goodies that Python 3.7 does, and we
need to support both. Add some compatibility wrappers needed for this
purpose.

(Note: Python 3.6 is EOL December 2021.)

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210915162955.333025-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

'T' is a common TypeVar name, allow its use.

See also https://github.com/PyCQA/pylint/issues/3401

 -- In the future,
we might be able to have a separate list of acceptable names for
TypeVars exclusively.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-4-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-3-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

For now, it's empty! Soon, it won't be.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20210915162955.333025-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

We're not ready to enforce f-strings everywhere, so just silence this
new warning.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Message-id: 20210916182248.721529-3-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

A few new annoyances. Of note is the new warning for an unspecified
encoding when opening a text file, which actually does indicate a
potentially real problem; see
https://www.python.org/dev/peps/pep-0597/#motivation



Use LC_CTYPE to determine an encoding to use for interpreting QEMU's
terminal output. Note that Python states: "language code and encoding
may be None if their values cannot be determined" -- use a platform
default as a backup.

Notes: Passing encoding=None will generate a suppressed warning on
Python 3.10+ that 'None' should not be passed as the encoding
argument. This behavior may be deprecated in the future and the default
switched to be a ubiquitous UTF-8. Opting in to the locale default will
be done by passing the encoding 'locale', but that isn't available in
3.6 through 3.9. Presumably this warning will be unsuppressed some time
prior to the actual switch and we can re-investigate these issues at
that time if necessary.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Message-id: 20210916182248.721529-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

mypy thinks that return value of these methods in subclusses is
QEMUMachine, which is wrong. So, make typing smarter.

Suggested-by: John Snow <jsnow@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210824083856.17408-26-vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

We often call qmp() with unpacking dict, like qmp('foo', **{...}).
mypy don't really like it, it thinks that passed unpacked dict is a
positional argument and complains that it type should be bool (because
second argument of qmp() is conv_keys: bool).

Allow passing dict directly, simplifying interface, and giving a way to
satisfy mypy.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-Id: <20210824083856.17408-25-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>