[PATCH v5 00/16] python: add mypy support to python/qemu

[PATCH v5 00/16] python: add mypy support to python/qemu

[John Snow]

Based-on: 20200710050649.32434-1-jsnow@redhat.com

This series modifies the python/qemu library to comply with mypy --strict,
pylint, and flake8.
This requires my "refactor shutdown" patch as a pre-requisite.

v5: (Things unchanged omitted)

003/16:[----] [-C] 'python/qmp.py: re-absorb MonitorResponseError'
009/16:[----] [-C] 'python/machine.py: Don't modify state in _base_args()'
012/16:[0004] [FC] 'python/machine.py: Add _qmp access shim'
013/16:[0002] [FC] 'python/machine.py: fix _popen access'
016/16:[0004] [FC] 'python/qemu: Add mypy type annotations'

--  Rebased on "refactor shutdown" v5
12: Dependent changes from more extensive shutdown() refactoring
13: Dependent changes; one less ._popen access.
16: Dependent changes; _post_shutdown return annotation fell down here.
                       wait annotation got bumped up to the previous series.

v4:
 - Rebased on "refactor shutdown" v4
 - Fixed _qmp access for scripts that disable QMP

v3:
005: Removed a cast, per Kevin Wolf's tip
010: Renamed with correct function name;
     Rewrote docstring and added comments
016: Use SocketAddrT instead of Union[Tuple[str,str],str]

"v2":
- This version supports iotests 297
- Many patches merged by Phil are removed
- Replaces iotests.py type aliases with centralized ones
  (See patch 2)
- Imports etc are reworked to use the non-installable
  package layout instead. (Mostly important for patch 3)

Testing this out:
- You'll need Python3.6+
- I encourage you to use a virtual environment!
- You don't necessarily need these exact versions, but I didn't test the
  lower bounds, use older versions at your peril:
  - pylint==2.5.0
  - mypy=0.770
  - flake8=3.7.8

> cd ~/src/qemu/python/
> flake8 qemu
> mypy --strict qemu
> cd qemu
> pylint *.py

These should all 100% pass.

John Snow (16):
  python/qmp.py: Define common types
  iotests.py: use qemu.qmp type aliases
  python/qmp.py: re-absorb MonitorResponseError
  python/qmp.py: Do not return None from cmd_obj
  python/qmp.py: add casts to JSON deserialization
  python/qmp.py: add QMPProtocolError
  python/machine.py: Fix monitor address typing
  python/machine.py: reorder __init__
  python/machine.py: Don't modify state in _base_args()
  python/machine.py: Handle None events in events_wait
  python/machine.py: use qmp.command
  python/machine.py: Add _qmp access shim
  python/machine.py: fix _popen access
  python/qemu: make 'args' style arguments immutable
  iotests.py: Adjust HMP kwargs typing
  python/qemu: Add mypy type annotations

 python/qemu/accel.py          |   8 +-
 python/qemu/machine.py        | 296 ++++++++++++++++++++--------------
 python/qemu/qmp.py            | 111 +++++++++----
 python/qemu/qtest.py          |  53 +++---
 scripts/render_block_graph.py |   7 +-
 tests/qemu-iotests/iotests.py |  11 +-
 6 files changed, 301 insertions(+), 185 deletions(-)

-- 
2.21.3

[PATCH v5 01/16] python/qmp.py: Define common types

[John Snow]

Define some common types that we'll need to annotate a lot of other
functions going forward.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/qmp.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index e64b6b5faa..8388c7b603 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -12,13 +12,31 @@
 import socket
 import logging
 from typing import (
+    Any,
+    Dict,
     Optional,
     TextIO,
     Type,
+    Tuple,
+    Union,
 )
 from types import TracebackType
 
 
+# QMPMessage is a QMP Message of any kind.
+# e.g. {'yee': 'haw'}
+#
+# QMPReturnValue is the inner value of return values only.
+# {'return': {}} is the QMPMessage,
+# {} is the QMPReturnValue.
+QMPMessage = Dict[str, Any]
+QMPReturnValue = Dict[str, Any]
+
+InternetAddrT = Tuple[str, str]
+UnixAddrT = str
+SocketAddrT = Union[InternetAddrT, UnixAddrT]
+
+
 class QMPError(Exception):
     """
     QMP base exception
-- 
2.21.3

[PATCH v5 02/16] iotests.py: use qemu.qmp type aliases

[John Snow]

iotests.py should use the type definitions from qmp.py instead of its
own.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/qemu-iotests/iotests.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index f1e0733dda..4457786f09 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -35,13 +35,10 @@
 # pylint: disable=import-error, wrong-import-position
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'python'))
 from qemu import qtest
+from qemu.qmp import QMPMessage
 
 assert sys.version_info >= (3, 6)
 
-# Type Aliases
-QMPResponse = Dict[str, Any]
-
-
 # Use this logger for logging messages directly from the iotests module
 logger = logging.getLogger('qemu.iotests')
 logger.addHandler(logging.NullHandler())
@@ -554,7 +551,7 @@ def add_incoming(self, addr):
         self._args.append(addr)
         return self
 
-    def hmp(self, command_line: str, use_log: bool = False) -> QMPResponse:
+    def hmp(self, command_line: str, use_log: bool = False) -> QMPMessage:
         cmd = 'human-monitor-command'
         kwargs = {'command-line': command_line}
         if use_log:
@@ -575,7 +572,7 @@ def resume_drive(self, drive: str) -> None:
         self.hmp(f'qemu-io {drive} "remove_break bp_{drive}"')
 
     def hmp_qemu_io(self, drive: str, cmd: str,
-                    use_log: bool = False) -> QMPResponse:
+                    use_log: bool = False) -> QMPMessage:
         """Write to a given drive using an HMP command"""
         return self.hmp(f'qemu-io {drive} "{cmd}"', use_log=use_log)
 
-- 
2.21.3

[PATCH v5 03/16] python/qmp.py: re-absorb MonitorResponseError

[John Snow]

When I initially split this out, I considered this more of a machine
error than a QMP protocol error, but I think that's misguided.

Move this back to qmp.py and name it QMPResponseError. Convert
qmp.command() to use this exception type.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/machine.py        | 15 +--------------
 python/qemu/qmp.py            | 17 +++++++++++++++--
 scripts/render_block_graph.py |  7 +++++--
 3 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index d08a8e4a6e..8ca3d508df 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -55,19 +55,6 @@ class AbnormalShutdown(QEMUMachineError):
     """
 
 
-class MonitorResponseError(qmp.QMPError):
-    """
-    Represents erroneous QMP monitor reply
-    """
-    def __init__(self, reply):
-        try:
-            desc = reply["error"]["desc"]
-        except KeyError:
-            desc = reply
-        super().__init__(desc)
-        self.reply = reply
-
-
 class QEMUMachine:
     """
     A QEMU VM
@@ -519,7 +506,7 @@ def command(self, cmd, conv_keys=True, **args):
         if reply is None:
             raise qmp.QMPError("Monitor is closed")
         if "error" in reply:
-            raise MonitorResponseError(reply)
+            raise qmp.QMPResponseError(reply)
         return reply["return"]
 
     def get_qmp_event(self, wait=False):
diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index 8388c7b603..aa8a666b8a 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -61,6 +61,19 @@ class QMPTimeoutError(QMPError):
     """
 
 
+class QMPResponseError(QMPError):
+    """
+    Represents erroneous QMP monitor reply
+    """
+    def __init__(self, reply: QMPMessage):
+        try:
+            desc = reply['error']['desc']
+        except KeyError:
+            desc = reply
+        super().__init__(desc)
+        self.reply = reply
+
+
 class QEMUMonitorProtocol:
     """
     Provide an API to connect to QEMU via QEMU Monitor Protocol (QMP) and then
@@ -251,8 +264,8 @@ def command(self, cmd, **kwds):
         Build and send a QMP command to the monitor, report errors if any
         """
         ret = self.cmd(cmd, kwds)
-        if "error" in ret:
-            raise Exception(ret['error']['desc'])
+        if 'error' in ret:
+            raise QMPResponseError(ret)
         return ret['return']
 
     def pull_event(self, wait=False):
diff --git a/scripts/render_block_graph.py b/scripts/render_block_graph.py
index 409b4321f2..da6acf050d 100755
--- a/scripts/render_block_graph.py
+++ b/scripts/render_block_graph.py
@@ -25,7 +25,10 @@
 from graphviz import Digraph
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'python'))
-from qemu.machine import MonitorResponseError
+from qemu.qmp import (
+    QEMUMonitorProtocol,
+    QMPResponseError,
+)
 
 
 def perm(arr):
@@ -102,7 +105,7 @@ def command(self, cmd):
         reply = json.loads(subprocess.check_output(ar))
 
         if 'error' in reply:
-            raise MonitorResponseError(reply)
+            raise QMPResponseError(reply)
 
         return reply['return']
 
-- 
2.21.3

[PATCH v5 04/16] python/qmp.py: Do not return None from cmd_obj

[John Snow]

This makes typing the qmp library difficult, as it necessitates wrapping
Optional[] around the type for every return type up the stack. At some
point, it becomes difficult to discern or remember why it's None instead
of the expected object.

Use the python exception system to tell us exactly why we didn't get an
object. Remove this special-cased return.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/qmp.py | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index aa8a666b8a..ef3c919b76 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -225,22 +225,18 @@ def accept(self, timeout=15.0):
         self.__sockfile = self.__sock.makefile(mode='r')
         return self.__negotiate_capabilities()
 
-    def cmd_obj(self, qmp_cmd):
+    def cmd_obj(self, qmp_cmd: QMPMessage) -> QMPMessage:
         """
         Send a QMP command to the QMP Monitor.
 
         @param qmp_cmd: QMP command to be sent as a Python dict
-        @return QMP response as a Python dict or None if the connection has
-                been closed
+        @return QMP response as a Python dict
         """
         self.logger.debug(">>> %s", qmp_cmd)
-        try:
-            self.__sock.sendall(json.dumps(qmp_cmd).encode('utf-8'))
-        except OSError as err:
-            if err.errno == errno.EPIPE:
-                return None
-            raise err
+        self.__sock.sendall(json.dumps(qmp_cmd).encode('utf-8'))
         resp = self.__json_read()
+        if resp is None:
+            raise QMPConnectError("Unexpected empty reply from server")
         self.logger.debug("<<< %s", resp)
         return resp
 
-- 
2.21.3

[PATCH v5 05/16] python/qmp.py: add casts to JSON deserialization

[John Snow]

mypy and python type hints are not powerful enough to properly describe
JSON messages in Python 3.6. The best we can do, generally, is describe
them as Dict[str, Any].

Add casts to coerce this type for static analysis; but do NOT enforce
this type at runtime in any way.

Note: Python 3.8 adds a TypedDict construct which allows for the
description of more arbitrary Dictionary shapes. There is a third-party
module, "Pydantic", which is compatible with 3.6 that can be used
instead of the JSON library that parses JSON messages to fully-typed
Python objects, and may be preferable in some cases.

(That is well beyond the scope of this commit or series.)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/qmp.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index ef3c919b76..1ae36050a4 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -13,6 +13,7 @@
 import logging
 from typing import (
     Any,
+    cast,
     Dict,
     Optional,
     TextIO,
@@ -130,7 +131,10 @@ def __json_read(self, only_event=False):
             data = self.__sockfile.readline()
             if not data:
                 return None
-            resp = json.loads(data)
+            # By definition, any JSON received from QMP is a QMPMessage,
+            # and we are asserting only at static analysis time that it
+            # has a particular shape.
+            resp: QMPMessage = json.loads(data)
             if 'event' in resp:
                 self.logger.debug("<<< %s", resp)
                 self.__events.append(resp)
@@ -262,7 +266,7 @@ def command(self, cmd, **kwds):
         ret = self.cmd(cmd, kwds)
         if 'error' in ret:
             raise QMPResponseError(ret)
-        return ret['return']
+        return cast(QMPReturnValue, ret['return'])
 
     def pull_event(self, wait=False):
         """
-- 
2.21.3

[PATCH v5 06/16] python/qmp.py: add QMPProtocolError

[John Snow]

In the case that we receive a reply but are unable to understand it, use
this exception name to indicate that case.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/qmp.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index 1ae36050a4..7935dababb 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -62,6 +62,12 @@ class QMPTimeoutError(QMPError):
     """
 
 
+class QMPProtocolError(QMPError):
+    """
+    QMP protocol error; unexpected response
+    """
+
+
 class QMPResponseError(QMPError):
     """
     Represents erroneous QMP monitor reply
@@ -266,6 +272,10 @@ def command(self, cmd, **kwds):
         ret = self.cmd(cmd, kwds)
         if 'error' in ret:
             raise QMPResponseError(ret)
+        if 'return' not in ret:
+            raise QMPProtocolError(
+                "'return' key not found in QMP response '{}'".format(str(ret))
+            )
         return cast(QMPReturnValue, ret['return'])
 
     def pull_event(self, wait=False):
-- 
2.21.3

[PATCH v5 07/16] python/machine.py: Fix monitor address typing

[John Snow]

Prior to this, it's difficult for mypy to intuit what the concrete type
of the monitor address is; it has difficulty inferring the type across
two variables.

Create _monitor_address as a property that always returns a valid
address to simplify static type analysis.

To preserve our ability to clean up, use a simple boolean to indicate
whether or not we should try to clean up the sock file after execution.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/machine.py | 45 +++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 8ca3d508df..bab1b1921f 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -25,10 +25,14 @@
 import signal
 import socket
 import tempfile
-from typing import Optional, Type
+from typing import (
+    Optional,
+    Type,
+)
 from types import TracebackType
 
 from . import qmp
+from .qmp import SocketAddrT
 
 LOG = logging.getLogger(__name__)
 
@@ -68,7 +72,8 @@ class QEMUMachine:
     """
 
     def __init__(self, binary, args=None, wrapper=None, name=None,
-                 test_dir="/var/tmp", monitor_address=None,
+                 test_dir="/var/tmp",
+                 monitor_address: Optional[SocketAddrT] = None,
                  socket_scm_helper=None, sock_dir=None):
         '''
         Initialize a QEMUMachine
@@ -91,8 +96,14 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         if sock_dir is None:
             sock_dir = test_dir
         self._name = name
-        self._monitor_address = monitor_address
-        self._vm_monitor = None
+        if monitor_address is not None:
+            self._monitor_address = monitor_address
+            self._remove_monitor_sockfile = False
+        else:
+            self._monitor_address = os.path.join(
+                sock_dir, f"{name}-monitor.sock"
+            )
+            self._remove_monitor_sockfile = True
         self._qemu_log_path = None
         self._qemu_log_file = None
         self._popen = None
@@ -231,15 +242,17 @@ def _load_io_log(self):
 
     def _base_args(self):
         args = ['-display', 'none', '-vga', 'none']
+
         if self._qmp_set:
             if isinstance(self._monitor_address, tuple):
-                moncdev = "socket,id=mon,host=%s,port=%s" % (
-                    self._monitor_address[0],
-                    self._monitor_address[1])
+                moncdev = "socket,id=mon,host={},port={}".format(
+                    *self._monitor_address
+                )
             else:
-                moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
+                moncdev = f"socket,id=mon,path={self._monitor_address}"
             args.extend(['-chardev', moncdev, '-mon',
                          'chardev=mon,mode=control'])
+
         if self._machine is not None:
             args.extend(['-machine', self._machine])
         for _ in range(self._console_index):
@@ -264,14 +277,14 @@ def _pre_launch(self):
         self._qemu_log_file = open(self._qemu_log_path, 'wb')
 
         if self._qmp_set:
-            if self._monitor_address is not None:
-                self._vm_monitor = self._monitor_address
-            else:
-                self._vm_monitor = os.path.join(self._sock_dir,
-                                                self._name + "-monitor.sock")
-                self._remove_files.append(self._vm_monitor)
-            self._qmp = qmp.QEMUMonitorProtocol(self._vm_monitor, server=True,
-                                                nickname=self._name)
+            if self._remove_monitor_sockfile:
+                assert isinstance(self._monitor_address, str)
+                self._remove_files.append(self._monitor_address)
+            self._qmp = qmp.QEMUMonitorProtocol(
+                self._monitor_address,
+                server=True,
+                nickname=self._name
+            )
 
     def _post_launch(self):
         if self._qmp:
-- 
2.21.3

[PATCH v5 08/16] python/machine.py: reorder __init__

[John Snow]

Put the init arg handling all at the top, and mostly in order (deviating
when one is dependent on another), and put what is effectively runtime
state declaration at the bottom.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/machine.py | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index bab1b1921f..0f7ec095cb 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -87,38 +87,43 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         @param socket_scm_helper: helper program, required for send_fd_scm()
         @note: Qemu process is not started until launch() is used.
         '''
+        # Direct user configuration
+
+        self._binary = binary
+
         if args is None:
             args = []
+        # Copy mutable input: we will be modifying our copy
+        self._args = list(args)
+
         if wrapper is None:
             wrapper = []
-        if name is None:
-            name = "qemu-%d" % os.getpid()
-        if sock_dir is None:
-            sock_dir = test_dir
-        self._name = name
+        self._wrapper = wrapper
+
+        self._name = name or "qemu-%d" % os.getpid()
+        self._test_dir = test_dir
+        self._sock_dir = sock_dir or self._test_dir
+        self._socket_scm_helper = socket_scm_helper
+
         if monitor_address is not None:
             self._monitor_address = monitor_address
             self._remove_monitor_sockfile = False
         else:
             self._monitor_address = os.path.join(
-                sock_dir, f"{name}-monitor.sock"
+                self._sock_dir, f"{self._name}-monitor.sock"
             )
             self._remove_monitor_sockfile = True
+
+        # Runstate
         self._qemu_log_path = None
         self._qemu_log_file = None
         self._popen = None
-        self._binary = binary
-        self._args = list(args)     # Force copy args in case we modify them
-        self._wrapper = wrapper
         self._events = []
         self._iolog = None
-        self._socket_scm_helper = socket_scm_helper
         self._qmp_set = True   # Enable QMP monitor by default.
         self._qmp = None
         self._qemu_full_args = None
-        self._test_dir = test_dir
         self._temp_dir = None
-        self._sock_dir = sock_dir
         self._launched = False
         self._machine = None
         self._console_index = 0
-- 
2.21.3

[PATCH v5 09/16] python/machine.py: Don't modify state in _base_args()

[John Snow]

Don't append to the _remove_files list during _base_args; instead do so
during _launch. Rework _base_args as a @property to help facilitate
this impression.

This has the additional benefit of making the type of _console_address
easier to analyze statically.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/machine.py | 16 ++++++++++------
 python/qemu/qtest.py   | 11 ++++++++---
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 0f7ec095cb..37e859f6d2 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -26,6 +26,7 @@
 import socket
 import tempfile
 from typing import (
+    List,
     Optional,
     Type,
 )
@@ -129,7 +130,9 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         self._console_index = 0
         self._console_set = False
         self._console_device_type = None
-        self._console_address = None
+        self._console_address = os.path.join(
+            self._sock_dir, f"{self._name}-console.sock"
+        )
         self._console_socket = None
         self._remove_files = []
         self._user_killed = False
@@ -245,7 +248,8 @@ def _load_io_log(self):
             with open(self._qemu_log_path, "r") as iolog:
                 self._iolog = iolog.read()
 
-    def _base_args(self):
+    @property
+    def _base_args(self) -> List[str]:
         args = ['-display', 'none', '-vga', 'none']
 
         if self._qmp_set:
@@ -263,9 +267,6 @@ def _base_args(self):
         for _ in range(self._console_index):
             args.extend(['-serial', 'null'])
         if self._console_set:
-            self._console_address = os.path.join(self._sock_dir,
-                                                 self._name + "-console.sock")
-            self._remove_files.append(self._console_address)
             chardev = ('socket,id=console,path=%s,server,nowait' %
                        self._console_address)
             args.extend(['-chardev', chardev])
@@ -281,6 +282,9 @@ def _pre_launch(self):
         self._qemu_log_path = os.path.join(self._temp_dir, self._name + ".log")
         self._qemu_log_file = open(self._qemu_log_path, 'wb')
 
+        if self._console_set:
+            self._remove_files.append(self._console_address)
+
         if self._qmp_set:
             if self._remove_monitor_sockfile:
                 assert isinstance(self._monitor_address, str)
@@ -366,7 +370,7 @@ def _launch(self):
         devnull = open(os.path.devnull, 'rb')
         self._pre_launch()
         self._qemu_full_args = (self._wrapper + [self._binary] +
-                                self._base_args() + self._args)
+                                self._base_args + self._args)
         LOG.debug('VM launch command: %r', ' '.join(self._qemu_full_args))
         self._popen = subprocess.Popen(self._qemu_full_args,
                                        stdin=devnull,
diff --git a/python/qemu/qtest.py b/python/qemu/qtest.py
index 888c8bd2f6..05c63a1d58 100644
--- a/python/qemu/qtest.py
+++ b/python/qemu/qtest.py
@@ -19,7 +19,11 @@
 
 import socket
 import os
-from typing import Optional, TextIO
+from typing import (
+    List,
+    Optional,
+    TextIO,
+)
 
 from .machine import QEMUMachine
 
@@ -111,8 +115,9 @@ def __init__(self, binary, args=None, name=None, test_dir="/var/tmp",
         self._qtest = None
         self._qtest_path = os.path.join(sock_dir, name + "-qtest.sock")
 
-    def _base_args(self):
-        args = super()._base_args()
+    @property
+    def _base_args(self) -> List[str]:
+        args = super()._base_args
         args.extend(['-qtest', 'unix:path=' + self._qtest_path,
                      '-accel', 'qtest'])
         return args
-- 
2.21.3

[PATCH v5 10/16] python/machine.py: Handle None events in events_wait

[John Snow]

If the timeout is 0, we can get None back. Handle this explicitly.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/machine.py | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 37e859f6d2..48e70253fa 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -33,7 +33,7 @@
 from types import TracebackType
 
 from . import qmp
-from .qmp import SocketAddrT
+from .qmp import SocketAddrT, QMPMessage
 
 LOG = logging.getLogger(__name__)
 
@@ -594,13 +594,20 @@ def event_wait(self, name, timeout=60.0, match=None):
 
     def events_wait(self, events, timeout=60.0):
         """
-        events_wait waits for and returns a named event
-        from QMP with a timeout.
+        events_wait waits for and returns a single named event from QMP.
+        In the case of multiple qualifying events, this function returns the
+        first one.
 
-        events: a sequence of (name, match_criteria) tuples.
-                The match criteria are optional and may be None.
-                See event_match for details.
-        timeout: QEMUMonitorProtocol.pull_event timeout parameter.
+        :param events: A sequence of (name, match_criteria) tuples.
+                       The match criteria are optional and may be None.
+                       See event_match for details.
+        :param timeout: Optional timeout, in seconds.
+                        See QEMUMonitorProtocol.pull_event.
+
+        :raise QMPTimeoutError: If timeout was non-zero and no matching events
+                                were found.
+        :return: A QMP event matching the filter criteria.
+                 If timeout was 0 and no event matched, None.
         """
         def _match(event):
             for name, match in events:
@@ -608,6 +615,8 @@ def _match(event):
                     return True
             return False
 
+        event: Optional[QMPMessage]
+
         # Search cached events
         for event in self._events:
             if _match(event):
@@ -617,6 +626,10 @@ def _match(event):
         # Poll for new events
         while True:
             event = self._qmp.pull_event(wait=timeout)
+            if event is None:
+                # NB: None is only returned when timeout is false-ish.
+                # Timeouts raise QMPTimeoutError instead!
+                break
             if _match(event):
                 return event
             self._events.append(event)
-- 
2.21.3

[PATCH v5 11/16] python/machine.py: use qmp.command

[John Snow]

machine.py and qmp.py both do the same thing here; refactor machine.py
to use qmp.py's functionality more directly.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/machine.py | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 48e70253fa..0df94c3211 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -26,6 +26,8 @@
 import socket
 import tempfile
 from typing import (
+    Any,
+    Dict,
     List,
     Optional,
     Type,
@@ -505,17 +507,23 @@ def set_qmp_monitor(self, enabled=True):
             self._qmp_set = False
             self._qmp = None
 
-    def qmp(self, cmd, conv_keys=True, **args):
-        """
-        Invoke a QMP command and return the response dict
-        """
+    @classmethod
+    def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
         qmp_args = dict()
         for key, value in args.items():
-            if conv_keys:
+            if _conv_keys:
                 qmp_args[key.replace('_', '-')] = value
             else:
                 qmp_args[key] = value
+        return qmp_args
 
+    def qmp(self, cmd: str,
+            conv_keys: bool = True,
+            **args: Any) -> QMPMessage:
+        """
+        Invoke a QMP command and return the response dict
+        """
+        qmp_args = self._qmp_args(conv_keys, **args)
         return self._qmp.cmd(cmd, args=qmp_args)
 
     def command(self, cmd, conv_keys=True, **args):
@@ -524,12 +532,8 @@ def command(self, cmd, conv_keys=True, **args):
         On success return the response dict.
         On failure raise an exception.
         """
-        reply = self.qmp(cmd, conv_keys, **args)
-        if reply is None:
-            raise qmp.QMPError("Monitor is closed")
-        if "error" in reply:
-            raise qmp.QMPResponseError(reply)
-        return reply["return"]
+        qmp_args = self._qmp_args(conv_keys, **args)
+        return self._qmp.command(cmd, **qmp_args)
 
     def get_qmp_event(self, wait=False):
         """
-- 
2.21.3

[PATCH v5 12/16] python/machine.py: Add _qmp access shim

[John Snow]

Like many other Optional[] types, it's not always a given that this
object will be set. Wrap it in a type-shim that raises a meaningful
error and will always return a concrete type.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 0df94c3211..9760a2badb 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -124,7 +124,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         self._events = []
         self._iolog = None
         self._qmp_set = True   # Enable QMP monitor by default.
-        self._qmp = None
+        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
         self._qemu_full_args = None
         self._temp_dir = None
         self._launched = False
@@ -291,14 +291,14 @@ def _pre_launch(self):
             if self._remove_monitor_sockfile:
                 assert isinstance(self._monitor_address, str)
                 self._remove_files.append(self._monitor_address)
-            self._qmp = qmp.QEMUMonitorProtocol(
+            self._qmp_connection = qmp.QEMUMonitorProtocol(
                 self._monitor_address,
                 server=True,
                 nickname=self._name
             )
 
     def _post_launch(self):
-        if self._qmp:
+        if self._qmp_connection:
             self._qmp.accept()
 
     def _post_shutdown(self):
@@ -309,9 +309,9 @@ def _post_shutdown(self):
         # Comprehensive reset for the failed launch case:
         self._early_cleanup()
 
-        if self._qmp:
+        if self._qmp_connection:
             self._qmp.close()
-            self._qmp = None
+            self._qmp_connection = None
 
         self._load_io_log()
 
@@ -423,7 +423,7 @@ def _soft_shutdown(self, has_quit: bool = False,
         """
         self._early_cleanup()
 
-        if self._qmp is not None:
+        if self._qmp_connection:
             if not has_quit:
                 # Might raise ConnectionReset
                 self._qmp.cmd('quit')
@@ -501,11 +501,13 @@ def set_qmp_monitor(self, enabled=True):
                         line. Default is True.
         @note: call this function before launch().
         """
-        if enabled:
-            self._qmp_set = True
-        else:
-            self._qmp_set = False
-            self._qmp = None
+        self._qmp_set = enabled
+
+    @property
+    def _qmp(self) -> qmp.QEMUMonitorProtocol:
+        if self._qmp_connection is None:
+            raise QEMUMachineError("Attempt to access QMP with no connection")
+        return self._qmp_connection
 
     @classmethod
     def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
-- 
2.21.3

[PATCH v5 13/16] python/machine.py: fix _popen access

[John Snow]

As always, Optional[T] causes problems with unchecked access. Add a
helper that asserts the pipe is present before we attempt to talk with
it.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 9760a2badb..2ba5e3134e 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -120,7 +120,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         # Runstate
         self._qemu_log_path = None
         self._qemu_log_file = None
-        self._popen = None
+        self._popen: Optional['subprocess.Popen[bytes]'] = None
         self._events = []
         self._iolog = None
         self._qmp_set = True   # Enable QMP monitor by default.
@@ -233,6 +233,12 @@ def is_running(self):
         """Returns true if the VM is running."""
         return self._popen is not None and self._popen.poll() is None
 
+    @property
+    def _subp(self) -> 'subprocess.Popen[bytes]':
+        if self._popen is None:
+            raise QEMUMachineError('Subprocess pipe not present')
+        return self._popen
+
     def exitcode(self):
         """Returns the exit code if possible, or None."""
         if self._popen is None:
@@ -243,7 +249,7 @@ def get_pid(self):
         """Returns the PID of the running process, or None."""
         if not self.is_running():
             return None
-        return self._popen.pid
+        return self._subp.pid
 
     def _load_io_log(self):
         if self._qemu_log_path is not None:
@@ -404,8 +410,8 @@ def _hard_shutdown(self) -> None:
             waiting for the QEMU process to terminate.
         """
         self._early_cleanup()
-        self._popen.kill()
-        self._popen.wait(timeout=60)
+        self._subp.kill()
+        self._subp.wait(timeout=60)
 
     def _soft_shutdown(self, has_quit: bool = False,
                        timeout: Optional[int] = 3) -> None:
@@ -429,7 +435,7 @@ def _soft_shutdown(self, has_quit: bool = False,
                 self._qmp.cmd('quit')
 
         # May raise subprocess.TimeoutExpired
-        self._popen.wait(timeout=timeout)
+        self._subp.wait(timeout=timeout)
 
     def _do_shutdown(self, has_quit: bool = False,
                      timeout: Optional[int] = 3) -> None:
-- 
2.21.3

[PATCH v5 14/16] python/qemu: make 'args' style arguments immutable

[John Snow]

These arguments don't need to be mutable and aren't really used as
such. Clarify their types as immutable and adjust code to match where
necessary.

In general, It's probably best not to accept a user-defined mutable
object and store it as internal object state unless there's a strong
justification for doing so. Instead, try to use generic types as input
with empty tuples as the default, and coerce to list where necessary.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 python/qemu/machine.py | 30 +++++++++++++++++-------------
 python/qemu/qtest.py   | 16 ++++++++++++----
 2 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 2ba5e3134e..f7239a249b 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -18,6 +18,7 @@
 #
 
 import errno
+from itertools import chain
 import logging
 import os
 import subprocess
@@ -30,6 +31,8 @@
     Dict,
     List,
     Optional,
+    Sequence,
+    Tuple,
     Type,
 )
 from types import TracebackType
@@ -74,8 +77,12 @@ class QEMUMachine:
         # vm is guaranteed to be shut down here
     """
 
-    def __init__(self, binary, args=None, wrapper=None, name=None,
-                 test_dir="/var/tmp",
+    def __init__(self,
+                 binary: str,
+                 args: Sequence[str] = (),
+                 wrapper: Sequence[str] = (),
+                 name: Optional[str] = None,
+                 test_dir: str = "/var/tmp",
                  monitor_address: Optional[SocketAddrT] = None,
                  socket_scm_helper=None, sock_dir=None):
         '''
@@ -93,14 +100,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         # Direct user configuration
 
         self._binary = binary
-
-        if args is None:
-            args = []
-        # Copy mutable input: we will be modifying our copy
         self._args = list(args)
-
-        if wrapper is None:
-            wrapper = []
         self._wrapper = wrapper
 
         self._name = name or "qemu-%d" % os.getpid()
@@ -125,7 +125,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         self._iolog = None
         self._qmp_set = True   # Enable QMP monitor by default.
         self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
-        self._qemu_full_args = None
+        self._qemu_full_args: Tuple[str, ...] = ()
         self._temp_dir = None
         self._launched = False
         self._machine = None
@@ -357,7 +357,7 @@ def launch(self):
             raise QEMUMachineError('VM already launched')
 
         self._iolog = None
-        self._qemu_full_args = None
+        self._qemu_full_args = ()
         try:
             self._launch()
             self._launched = True
@@ -377,8 +377,12 @@ def _launch(self):
         """
         devnull = open(os.path.devnull, 'rb')
         self._pre_launch()
-        self._qemu_full_args = (self._wrapper + [self._binary] +
-                                self._base_args + self._args)
+        self._qemu_full_args = tuple(
+            chain(self._wrapper,
+                  [self._binary],
+                  self._base_args,
+                  self._args)
+        )
         LOG.debug('VM launch command: %r', ' '.join(self._qemu_full_args))
         self._popen = subprocess.Popen(self._qemu_full_args,
                                        stdin=devnull,
diff --git a/python/qemu/qtest.py b/python/qemu/qtest.py
index 05c63a1d58..ae4661d4d3 100644
--- a/python/qemu/qtest.py
+++ b/python/qemu/qtest.py
@@ -22,6 +22,7 @@
 from typing import (
     List,
     Optional,
+    Sequence,
     TextIO,
 )
 
@@ -103,8 +104,13 @@ class QEMUQtestMachine(QEMUMachine):
     A QEMU VM, with a qtest socket available.
     """
 
-    def __init__(self, binary, args=None, name=None, test_dir="/var/tmp",
-                 socket_scm_helper=None, sock_dir=None):
+    def __init__(self,
+                 binary: str,
+                 args: Sequence[str] = (),
+                 name: Optional[str] = None,
+                 test_dir: str = "/var/tmp",
+                 socket_scm_helper: Optional[str] = None,
+                 sock_dir: Optional[str] = None):
         if name is None:
             name = "qemu-%d" % os.getpid()
         if sock_dir is None:
@@ -118,8 +124,10 @@ def __init__(self, binary, args=None, name=None, test_dir="/var/tmp",
     @property
     def _base_args(self) -> List[str]:
         args = super()._base_args
-        args.extend(['-qtest', 'unix:path=' + self._qtest_path,
-                     '-accel', 'qtest'])
+        args.extend([
+            '-qtest', f"unix:path={self._qtest_path}",
+            '-accel', 'qtest'
+        ])
         return args
 
     def _pre_launch(self):
-- 
2.21.3

[PATCH v5 15/16] iotests.py: Adjust HMP kwargs typing

[John Snow]

mypy wants to ensure there's consistency between the kwargs arguments
types and any unspecified keyword arguments. In this case, conv_keys is
a bool, but the remaining keys are Any type. Mypy (correctly) infers the
**kwargs type to be **Dict[str, str], which is not compatible with
conv_keys: bool.

Because QMP typing is a little fraught right now anyway, re-type kwargs
to Dict[str, Any] which has the benefit of silencing this check right
now.

A future re-design might type these more aggressively, but this will
give us a baseline to work from with minimal disruption.

(Thanks Kevin Wolf for the debugging assist here)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/qemu-iotests/iotests.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 4457786f09..d5cde7c0da 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -553,7 +553,7 @@ def add_incoming(self, addr):
 
     def hmp(self, command_line: str, use_log: bool = False) -> QMPMessage:
         cmd = 'human-monitor-command'
-        kwargs = {'command-line': command_line}
+        kwargs: Dict[str, Any] = {'command-line': command_line}
         if use_log:
             return self.qmp_log(cmd, **kwargs)
         else:
-- 
2.21.3

[PATCH v5 16/16] python/qemu: Add mypy type annotations

[John Snow]

These should all be purely annotations with no changes in behavior at
all. You need to be in the python folder, but you should be able to
confirm that these annotations are correct (or at least self-consistent)
by running `mypy --strict qemu`.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/accel.py   |  8 ++--
 python/qemu/machine.py | 94 ++++++++++++++++++++++++------------------
 python/qemu/qmp.py     | 44 +++++++++++---------
 python/qemu/qtest.py   | 26 +++++++-----
 4 files changed, 98 insertions(+), 74 deletions(-)

diff --git a/python/qemu/accel.py b/python/qemu/accel.py
index 7fabe62920..4325114e51 100644
--- a/python/qemu/accel.py
+++ b/python/qemu/accel.py
@@ -17,6 +17,7 @@
 import logging
 import os
 import subprocess
+from typing import List, Optional
 
 LOG = logging.getLogger(__name__)
 
@@ -29,7 +30,7 @@
 }
 
 
-def list_accel(qemu_bin):
+def list_accel(qemu_bin: str) -> List[str]:
     """
     List accelerators enabled in the QEMU binary.
 
@@ -49,7 +50,8 @@ def list_accel(qemu_bin):
     return [acc.strip() for acc in out.splitlines()[1:]]
 
 
-def kvm_available(target_arch=None, qemu_bin=None):
+def kvm_available(target_arch: Optional[str] = None,
+                  qemu_bin: Optional[str] = None) -> bool:
     """
     Check if KVM is available using the following heuristic:
       - Kernel module is present in the host;
@@ -72,7 +74,7 @@ def kvm_available(target_arch=None, qemu_bin=None):
     return True
 
 
-def tcg_available(qemu_bin):
+def tcg_available(qemu_bin: str) -> bool:
     """
     Check if TCG is available.
 
diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index f7239a249b..3f0c98987f 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -28,6 +28,7 @@
 import tempfile
 from typing import (
     Any,
+    BinaryIO,
     Dict,
     List,
     Optional,
@@ -38,7 +39,7 @@
 from types import TracebackType
 
 from . import qmp
-from .qmp import SocketAddrT, QMPMessage
+from .qmp import QMPMessage, QMPReturnValue, SocketAddrT
 
 LOG = logging.getLogger(__name__)
 
@@ -67,7 +68,7 @@ class AbnormalShutdown(QEMUMachineError):
 
 class QEMUMachine:
     """
-    A QEMU VM
+    A QEMU VM.
 
     Use this object as a context manager to ensure
     the QEMU process terminates::
@@ -84,7 +85,8 @@ def __init__(self,
                  name: Optional[str] = None,
                  test_dir: str = "/var/tmp",
                  monitor_address: Optional[SocketAddrT] = None,
-                 socket_scm_helper=None, sock_dir=None):
+                 socket_scm_helper: Optional[str] = None,
+                 sock_dir: Optional[str] = None):
         '''
         Initialize a QEMUMachine
 
@@ -118,28 +120,28 @@ def __init__(self,
             self._remove_monitor_sockfile = True
 
         # Runstate
-        self._qemu_log_path = None
-        self._qemu_log_file = None
+        self._qemu_log_path: Optional[str] = None
+        self._qemu_log_file: Optional[BinaryIO] = None
         self._popen: Optional['subprocess.Popen[bytes]'] = None
-        self._events = []
-        self._iolog = None
+        self._events: List[QMPMessage] = []
+        self._iolog: Optional[str] = None
         self._qmp_set = True   # Enable QMP monitor by default.
         self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
         self._qemu_full_args: Tuple[str, ...] = ()
-        self._temp_dir = None
+        self._temp_dir: Optional[str] = None
         self._launched = False
-        self._machine = None
+        self._machine: Optional[str] = None
         self._console_index = 0
         self._console_set = False
-        self._console_device_type = None
+        self._console_device_type: Optional[str] = None
         self._console_address = os.path.join(
             self._sock_dir, f"{self._name}-console.sock"
         )
-        self._console_socket = None
-        self._remove_files = []
+        self._console_socket: Optional[socket.socket] = None
+        self._remove_files: List[str] = []
         self._user_killed = False
 
-    def __enter__(self):
+    def __enter__(self) -> 'QEMUMachine':
         return self
 
     def __exit__(self,
@@ -148,14 +150,15 @@ def __exit__(self,
                  exc_tb: Optional[TracebackType]) -> None:
         self.shutdown()
 
-    def add_monitor_null(self):
+    def add_monitor_null(self) -> None:
         """
         This can be used to add an unused monitor instance.
         """
         self._args.append('-monitor')
         self._args.append('null')
 
-    def add_fd(self, fd, fdset, opaque, opts=''):
+    def add_fd(self, fd: int, fdset: int,
+               opaque: str, opts: str = '') -> 'QEMUMachine':
         """
         Pass a file descriptor to the VM
         """
@@ -174,7 +177,8 @@ def add_fd(self, fd, fdset, opaque, opts=''):
         self._args.append(','.join(options))
         return self
 
-    def send_fd_scm(self, fd=None, file_path=None):
+    def send_fd_scm(self, fd: Optional[int] = None,
+                    file_path: Optional[str] = None) -> int:
         """
         Send an fd or file_path to socket_scm_helper.
 
@@ -218,7 +222,7 @@ def send_fd_scm(self, fd=None, file_path=None):
         return proc.returncode
 
     @staticmethod
-    def _remove_if_exists(path):
+    def _remove_if_exists(path: str) -> None:
         """
         Remove file object at path if it exists
         """
@@ -229,7 +233,7 @@ def _remove_if_exists(path):
                 return
             raise
 
-    def is_running(self):
+    def is_running(self) -> bool:
         """Returns true if the VM is running."""
         return self._popen is not None and self._popen.poll() is None
 
@@ -239,19 +243,19 @@ def _subp(self) -> 'subprocess.Popen[bytes]':
             raise QEMUMachineError('Subprocess pipe not present')
         return self._popen
 
-    def exitcode(self):
+    def exitcode(self) -> Optional[int]:
         """Returns the exit code if possible, or None."""
         if self._popen is None:
             return None
         return self._popen.poll()
 
-    def get_pid(self):
+    def get_pid(self) -> Optional[int]:
         """Returns the PID of the running process, or None."""
         if not self.is_running():
             return None
         return self._subp.pid
 
-    def _load_io_log(self):
+    def _load_io_log(self) -> None:
         if self._qemu_log_path is not None:
             with open(self._qemu_log_path, "r") as iolog:
                 self._iolog = iolog.read()
@@ -285,7 +289,7 @@ def _base_args(self) -> List[str]:
                 args.extend(['-device', device])
         return args
 
-    def _pre_launch(self):
+    def _pre_launch(self) -> None:
         self._temp_dir = tempfile.mkdtemp(dir=self._test_dir)
         self._qemu_log_path = os.path.join(self._temp_dir, self._name + ".log")
         self._qemu_log_file = open(self._qemu_log_path, 'wb')
@@ -303,11 +307,11 @@ def _pre_launch(self):
                 nickname=self._name
             )
 
-    def _post_launch(self):
+    def _post_launch(self) -> None:
         if self._qmp_connection:
             self._qmp.accept()
 
-    def _post_shutdown(self):
+    def _post_shutdown(self) -> None:
         """
         Called to cleanup the VM instance after the process has exited.
         May also be called after a failed launch.
@@ -347,7 +351,7 @@ def _post_shutdown(self):
         self._user_killed = False
         self._launched = False
 
-    def launch(self):
+    def launch(self) -> None:
         """
         Launch the VM and make sure we cleanup and expose the
         command line/output in case of exception
@@ -371,7 +375,7 @@ def launch(self):
                 LOG.debug('Output: %r', self._iolog)
             raise
 
-    def _launch(self):
+    def _launch(self) -> None:
         """
         Launch the VM and establish a QMP connection
         """
@@ -487,7 +491,7 @@ def shutdown(self, has_quit: bool = False,
         finally:
             self._post_shutdown()
 
-    def kill(self):
+    def kill(self) -> None:
         """
         Terminate the VM forcefully, wait for it to exit, and perform cleanup.
         """
@@ -502,7 +506,7 @@ def wait(self, timeout: Optional[int] = 3) -> None:
         """
         self.shutdown(has_quit=True, timeout=timeout)
 
-    def set_qmp_monitor(self, enabled=True):
+    def set_qmp_monitor(self, enabled: bool = True) -> None:
         """
         Set the QMP monitor.
 
@@ -538,7 +542,9 @@ def qmp(self, cmd: str,
         qmp_args = self._qmp_args(conv_keys, **args)
         return self._qmp.cmd(cmd, args=qmp_args)
 
-    def command(self, cmd, conv_keys=True, **args):
+    def command(self, cmd: str,
+                conv_keys: bool = True,
+                **args: Any) -> QMPReturnValue:
         """
         Invoke a QMP command.
         On success return the response dict.
@@ -547,7 +553,7 @@ def command(self, cmd, conv_keys=True, **args):
         qmp_args = self._qmp_args(conv_keys, **args)
         return self._qmp.command(cmd, **qmp_args)
 
-    def get_qmp_event(self, wait=False):
+    def get_qmp_event(self, wait: bool = False) -> Optional[QMPMessage]:
         """
         Poll for one queued QMP events and return it
         """
@@ -555,7 +561,7 @@ def get_qmp_event(self, wait=False):
             return self._events.pop(0)
         return self._qmp.pull_event(wait=wait)
 
-    def get_qmp_events(self, wait=False):
+    def get_qmp_events(self, wait: bool = False) -> List[QMPMessage]:
         """
         Poll for queued QMP events and return a list of dicts
         """
@@ -566,7 +572,7 @@ def get_qmp_events(self, wait=False):
         return events
 
     @staticmethod
-    def event_match(event, match=None):
+    def event_match(event: Any, match: Optional[Any]) -> bool:
         """
         Check if an event matches optional match criteria.
 
@@ -596,9 +602,11 @@ def event_match(event, match=None):
             return True
         except TypeError:
             # either match or event wasn't iterable (not a dict)
-            return match == event
+            return bool(match == event)
 
-    def event_wait(self, name, timeout=60.0, match=None):
+    def event_wait(self, name: str,
+                   timeout: float = 60.0,
+                   match: Optional[QMPMessage] = None) -> Optional[QMPMessage]:
         """
         event_wait waits for and returns a named event from QMP with a timeout.
 
@@ -608,7 +616,9 @@ def event_wait(self, name, timeout=60.0, match=None):
         """
         return self.events_wait([(name, match)], timeout)
 
-    def events_wait(self, events, timeout=60.0):
+    def events_wait(self,
+                    events: Sequence[Tuple[str, Any]],
+                    timeout: float = 60.0) -> Optional[QMPMessage]:
         """
         events_wait waits for and returns a single named event from QMP.
         In the case of multiple qualifying events, this function returns the
@@ -625,7 +635,7 @@ def events_wait(self, events, timeout=60.0):
         :return: A QMP event matching the filter criteria.
                  If timeout was 0 and no event matched, None.
         """
-        def _match(event):
+        def _match(event: QMPMessage) -> bool:
             for name, match in events:
                 if event['event'] == name and self.event_match(event, match):
                     return True
@@ -652,20 +662,20 @@ def _match(event):
 
         return None
 
-    def get_log(self):
+    def get_log(self) -> Optional[str]:
         """
         After self.shutdown or failed qemu execution, this returns the output
         of the qemu process.
         """
         return self._iolog
 
-    def add_args(self, *args):
+    def add_args(self, *args: str) -> None:
         """
         Adds to the list of extra arguments to be given to the QEMU binary
         """
         self._args.extend(args)
 
-    def set_machine(self, machine_type):
+    def set_machine(self, machine_type: str) -> None:
         """
         Sets the machine type
 
@@ -674,7 +684,9 @@ def set_machine(self, machine_type):
         """
         self._machine = machine_type
 
-    def set_console(self, device_type=None, console_index=0):
+    def set_console(self,
+                    device_type: Optional[str] = None,
+                    console_index: int = 0) -> None:
         """
         Sets the device type for a console device
 
@@ -705,7 +717,7 @@ def set_console(self, device_type=None, console_index=0):
         self._console_index = console_index
 
     @property
-    def console_socket(self):
+    def console_socket(self) -> socket.socket:
         """
         Returns a socket connected to the console
         """
diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index 7935dababb..303e82ee6b 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -15,6 +15,7 @@
     Any,
     cast,
     Dict,
+    List,
     Optional,
     TextIO,
     Type,
@@ -90,7 +91,9 @@ class QEMUMonitorProtocol:
     #: Logger object for debugging messages
     logger = logging.getLogger('QMP')
 
-    def __init__(self, address, server=False, nickname=None):
+    def __init__(self, address: SocketAddrT,
+                 server: bool = False,
+                 nickname: Optional[str] = None):
         """
         Create a QEMUMonitorProtocol class.
 
@@ -102,7 +105,7 @@ def __init__(self, address, server=False, nickname=None):
         @note No connection is established, this is done by the connect() or
               accept() methods
         """
-        self.__events = []
+        self.__events: List[QMPMessage] = []
         self.__address = address
         self.__sock = self.__get_sock()
         self.__sockfile: Optional[TextIO] = None
@@ -114,14 +117,14 @@ def __init__(self, address, server=False, nickname=None):
             self.__sock.bind(self.__address)
             self.__sock.listen(1)
 
-    def __get_sock(self):
+    def __get_sock(self) -> socket.socket:
         if isinstance(self.__address, tuple):
             family = socket.AF_INET
         else:
             family = socket.AF_UNIX
         return socket.socket(family, socket.SOCK_STREAM)
 
-    def __negotiate_capabilities(self):
+    def __negotiate_capabilities(self) -> QMPMessage:
         greeting = self.__json_read()
         if greeting is None or "QMP" not in greeting:
             raise QMPConnectError
@@ -131,7 +134,7 @@ def __negotiate_capabilities(self):
             return greeting
         raise QMPCapabilitiesError
 
-    def __json_read(self, only_event=False):
+    def __json_read(self, only_event: bool = False) -> Optional[QMPMessage]:
         assert self.__sockfile is not None
         while True:
             data = self.__sockfile.readline()
@@ -148,7 +151,7 @@ def __json_read(self, only_event=False):
                     continue
             return resp
 
-    def __get_events(self, wait=False):
+    def __get_events(self, wait: Union[bool, float] = False) -> None:
         """
         Check for new events in the stream and cache them in __events.
 
@@ -186,7 +189,7 @@ def __get_events(self, wait=False):
                 raise QMPConnectError("Error while reading from socket")
             self.__sock.settimeout(None)
 
-    def __enter__(self):
+    def __enter__(self) -> 'QEMUMonitorProtocol':
         # Implement context manager enter function.
         return self
 
@@ -199,7 +202,7 @@ def __exit__(self,
         # Implement context manager exit function.
         self.close()
 
-    def connect(self, negotiate=True):
+    def connect(self, negotiate: bool = True) -> Optional[QMPMessage]:
         """
         Connect to the QMP Monitor and perform capabilities negotiation.
 
@@ -214,7 +217,7 @@ def connect(self, negotiate=True):
             return self.__negotiate_capabilities()
         return None
 
-    def accept(self, timeout=15.0):
+    def accept(self, timeout: float = 15.0) -> QMPMessage:
         """
         Await connection from QMP Monitor and perform capabilities negotiation.
 
@@ -250,7 +253,9 @@ def cmd_obj(self, qmp_cmd: QMPMessage) -> QMPMessage:
         self.logger.debug("<<< %s", resp)
         return resp
 
-    def cmd(self, name, args=None, cmd_id=None):
+    def cmd(self, name: str,
+            args: Optional[Dict[str, Any]] = None,
+            cmd_id: Optional[Any] = None) -> QMPMessage:
         """
         Build a QMP command and send it to the QMP Monitor.
 
@@ -258,14 +263,14 @@ def cmd(self, name, args=None, cmd_id=None):
         @param args: command arguments (dict)
         @param cmd_id: command id (dict, list, string or int)
         """
-        qmp_cmd = {'execute': name}
+        qmp_cmd: QMPMessage = {'execute': name}
         if args:
             qmp_cmd['arguments'] = args
         if cmd_id:
             qmp_cmd['id'] = cmd_id
         return self.cmd_obj(qmp_cmd)
 
-    def command(self, cmd, **kwds):
+    def command(self, cmd: str, **kwds: Any) -> QMPReturnValue:
         """
         Build and send a QMP command to the monitor, report errors if any
         """
@@ -278,7 +283,8 @@ def command(self, cmd, **kwds):
             )
         return cast(QMPReturnValue, ret['return'])
 
-    def pull_event(self, wait=False):
+    def pull_event(self,
+                   wait: Union[bool, float] = False) -> Optional[QMPMessage]:
         """
         Pulls a single event.
 
@@ -298,7 +304,7 @@ def pull_event(self, wait=False):
             return self.__events.pop(0)
         return None
 
-    def get_events(self, wait=False):
+    def get_events(self, wait: bool = False) -> List[QMPMessage]:
         """
         Get a list of available QMP events.
 
@@ -315,13 +321,13 @@ def get_events(self, wait=False):
         self.__get_events(wait)
         return self.__events
 
-    def clear_events(self):
+    def clear_events(self) -> None:
         """
         Clear current list of pending events.
         """
         self.__events = []
 
-    def close(self):
+    def close(self) -> None:
         """
         Close the socket and socket file.
         """
@@ -330,7 +336,7 @@ def close(self):
         if self.__sockfile:
             self.__sockfile.close()
 
-    def settimeout(self, timeout):
+    def settimeout(self, timeout: float) -> None:
         """
         Set the socket timeout.
 
@@ -339,7 +345,7 @@ def settimeout(self, timeout):
         """
         self.__sock.settimeout(timeout)
 
-    def get_sock_fd(self):
+    def get_sock_fd(self) -> int:
         """
         Get the socket file descriptor.
 
@@ -347,7 +353,7 @@ def get_sock_fd(self):
         """
         return self.__sock.fileno()
 
-    def is_scm_available(self):
+    def is_scm_available(self) -> bool:
         """
         Check if the socket allows for SCM_RIGHTS.
 
diff --git a/python/qemu/qtest.py b/python/qemu/qtest.py
index ae4661d4d3..49c04bc98d 100644
--- a/python/qemu/qtest.py
+++ b/python/qemu/qtest.py
@@ -27,6 +27,7 @@
 )
 
 from .machine import QEMUMachine
+from .qmp import SocketAddrT
 
 
 class QEMUQtestProtocol:
@@ -43,7 +44,8 @@ class QEMUQtestProtocol:
        No conection is estabalished by __init__(), this is done
        by the connect() or accept() methods.
     """
-    def __init__(self, address, server=False):
+    def __init__(self, address: SocketAddrT,
+                 server: bool = False):
         self._address = address
         self._sock = self._get_sock()
         self._sockfile: Optional[TextIO] = None
@@ -51,14 +53,14 @@ def __init__(self, address, server=False):
             self._sock.bind(self._address)
             self._sock.listen(1)
 
-    def _get_sock(self):
+    def _get_sock(self) -> socket.socket:
         if isinstance(self._address, tuple):
             family = socket.AF_INET
         else:
             family = socket.AF_UNIX
         return socket.socket(family, socket.SOCK_STREAM)
 
-    def connect(self):
+    def connect(self) -> None:
         """
         Connect to the qtest socket.
 
@@ -67,7 +69,7 @@ def connect(self):
         self._sock.connect(self._address)
         self._sockfile = self._sock.makefile(mode='r')
 
-    def accept(self):
+    def accept(self) -> None:
         """
         Await connection from QEMU.
 
@@ -76,7 +78,7 @@ def accept(self):
         self._sock, _ = self._sock.accept()
         self._sockfile = self._sock.makefile(mode='r')
 
-    def cmd(self, qtest_cmd):
+    def cmd(self, qtest_cmd: str) -> str:
         """
         Send a qtest command on the wire.
 
@@ -87,14 +89,16 @@ def cmd(self, qtest_cmd):
         resp = self._sockfile.readline()
         return resp
 
-    def close(self):
-        """Close this socket."""
+    def close(self) -> None:
+        """
+        Close this socket.
+        """
         self._sock.close()
         if self._sockfile:
             self._sockfile.close()
             self._sockfile = None
 
-    def settimeout(self, timeout):
+    def settimeout(self, timeout: Optional[float]) -> None:
         """Set a timeout, in seconds."""
         self._sock.settimeout(timeout)
 
@@ -118,7 +122,7 @@ def __init__(self,
         super().__init__(binary, args, name=name, test_dir=test_dir,
                          socket_scm_helper=socket_scm_helper,
                          sock_dir=sock_dir)
-        self._qtest = None
+        self._qtest: Optional[QEMUQtestProtocol] = None
         self._qtest_path = os.path.join(sock_dir, name + "-qtest.sock")
 
     @property
@@ -130,7 +134,7 @@ def _base_args(self) -> List[str]:
         ])
         return args
 
-    def _pre_launch(self):
+    def _pre_launch(self) -> None:
         super()._pre_launch()
         self._qtest = QEMUQtestProtocol(self._qtest_path, server=True)
 
@@ -139,7 +143,7 @@ def _post_launch(self) -> None:
         super()._post_launch()
         self._qtest.accept()
 
-    def _post_shutdown(self):
+    def _post_shutdown(self) -> None:
         super()._post_shutdown()
         self._remove_if_exists(self._qtest_path)
 
-- 
2.21.3

Re: [PATCH v5 13/16] python/machine.py: fix _popen access

[Philippe Mathieu-Daudé]

On 7/10/20 7:22 AM, John Snow wrote:
> As always, Optional[T] causes problems with unchecked access. Add a
> helper that asserts the pipe is present before we attempt to talk with
> it.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/machine.py | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)
> 

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Re: [PATCH v5 16/16] python/qemu: Add mypy type annotations

[Philippe Mathieu-Daudé]

On 7/10/20 7:22 AM, John Snow wrote:
> These should all be purely annotations with no changes in behavior at
> all. You need to be in the python folder, but you should be able to
> confirm that these annotations are correct (or at least self-consistent)
> by running `mypy --strict qemu`.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/accel.py   |  8 ++--
>  python/qemu/machine.py | 94 ++++++++++++++++++++++++------------------
>  python/qemu/qmp.py     | 44 +++++++++++---------
>  python/qemu/qtest.py   | 26 +++++++-----
>  4 files changed, 98 insertions(+), 74 deletions(-)
> 

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Re: [PATCH v5 12/16] python/machine.py: Add _qmp access shim

[Philippe Mathieu-Daudé]

On 7/10/20 7:22 AM, John Snow wrote:
> Like many other Optional[] types, it's not always a given that this
> object will be set. Wrap it in a type-shim that raises a meaningful
> error and will always return a concrete type.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/machine.py | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Re: [PATCH v5 00/16] python: add mypy support to python/qemu

[Philippe Mathieu-Daudé]

On 7/10/20 7:22 AM, John Snow wrote:
> Based-on: 20200710050649.32434-1-jsnow@redhat.com
> 
> This series modifies the python/qemu library to comply with mypy --strict,
> pylint, and flake8.
> This requires my "refactor shutdown" patch as a pre-requisite.
> 
[...]
> 
> These should all 100% pass.
> 
> John Snow (16):
>   python/qmp.py: Define common types
>   iotests.py: use qemu.qmp type aliases
>   python/qmp.py: re-absorb MonitorResponseError
>   python/qmp.py: Do not return None from cmd_obj
>   python/qmp.py: add casts to JSON deserialization
>   python/qmp.py: add QMPProtocolError

I've applied patches 1 to 6 on python-next, because unfortunately
then patch 7 now conflicts.

We'll merge them in 5.2 with the 'make check-python' rule patch last,
to avoid regressions.

Thanks,

Phil.

>   python/machine.py: Fix monitor address typing
>   python/machine.py: reorder __init__
>   python/machine.py: Don't modify state in _base_args()
>   python/machine.py: Handle None events in events_wait
>   python/machine.py: use qmp.command
>   python/machine.py: Add _qmp access shim
>   python/machine.py: fix _popen access
>   python/qemu: make 'args' style arguments immutable
>   iotests.py: Adjust HMP kwargs typing
>   python/qemu: Add mypy type annotations