python/qemu: split QEMUMachine out from underneath __init__.py

It's not obvious that something named __init__.py actually houses
important code that isn't relevant to python packaging glue. Move the
QEMUMachine and related error classes out into their own module.

Adjust users to the new import location.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20190627212816.27298-2-jsnow@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

1 files changed, 520 insertions, 0 deletions

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
new file mode 100644
index 0000000000..a8a311b035
--- /dev/null
+++ b/python/qemu/machine.py
@@ -0,0 +1,520 @@
+# QEMU library
+#
+# Copyright (C) 2015-2016 Red Hat Inc.
+# Copyright (C) 2012 IBM Corp.
+#
+# Authors:
+#  Fam Zheng <famz@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2.  See
+# the COPYING file in the top-level directory.
+#
+# Based on qmp.py.
+#
+
+import errno
+import logging
+import os
+import subprocess
+import re
+import shutil
+import socket
+import tempfile
+
+from . import qmp
+
+LOG = logging.getLogger(__name__)
+
+class QEMUMachineError(Exception):
+    """
+    Exception called when an error in QEMUMachine happens.
+    """
+
+
+class QEMUMachineAddDeviceError(QEMUMachineError):
+    """
+    Exception raised when a request to add a device can not be fulfilled
+
+    The failures are caused by limitations, lack of information or conflicting
+    requests on the QEMUMachine methods.  This exception does not represent
+    failures reported by the QEMU binary itself.
+    """
+
+
+class MonitorResponseError(qmp.QMPError):
+    """
+    Represents erroneous QMP monitor reply
+    """
+    def __init__(self, reply):
+        try:
+            desc = reply["error"]["desc"]
+        except KeyError:
+            desc = reply
+        super(MonitorResponseError, self).__init__(desc)
+        self.reply = reply
+
+
+class QEMUMachine(object):
+    """
+    A QEMU VM
+
+    Use this object as a context manager to ensure the QEMU process terminates::
+
+        with VM(binary) as vm:
+            ...
+        # vm is guaranteed to be shut down here
+    """
+
+    def __init__(self, binary, args=None, wrapper=None, name=None,
+                 test_dir="/var/tmp", monitor_address=None,
+                 socket_scm_helper=None):
+        '''
+        Initialize a QEMUMachine
+
+        @param binary: path to the qemu binary
+        @param args: list of extra arguments
+        @param wrapper: list of arguments used as prefix to qemu binary
+        @param name: prefix for socket and log file names (default: qemu-PID)
+        @param test_dir: where to create socket and log file
+        @param monitor_address: address for QMP monitor
+        @param socket_scm_helper: helper program, required for send_fd_scm()
+        @note: Qemu process is not started until launch() is used.
+        '''
+        if args is None:
+            args = []
+        if wrapper is None:
+            wrapper = []
+        if name is None:
+            name = "qemu-%d" % os.getpid()
+        self._name = name
+        self._monitor_address = monitor_address
+        self._vm_monitor = None
+        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 = None
+        self._qemu_full_args = None
+        self._test_dir = test_dir
+        self._temp_dir = None
+        self._launched = False
+        self._machine = None
+        self._console_set = False
+        self._console_device_type = None
+        self._console_address = None
+        self._console_socket = None
+
+        # just in case logging wasn't configured by the main script:
+        logging.basicConfig()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.shutdown()
+        return False
+
+    # This can be used to add an unused monitor instance.
+    def add_monitor_null(self):
+        self._args.append('-monitor')
+        self._args.append('null')
+
+    def add_fd(self, fd, fdset, opaque, opts=''):
+        """
+        Pass a file descriptor to the VM
+        """
+        options = ['fd=%d' % fd,
+                   'set=%d' % fdset,
+                   'opaque=%s' % opaque]
+        if opts:
+            options.append(opts)
+
+        # This did not exist before 3.4, but since then it is
+        # mandatory for our purpose
+        if hasattr(os, 'set_inheritable'):
+            os.set_inheritable(fd, True)
+
+        self._args.append('-add-fd')
+        self._args.append(','.join(options))
+        return self
+
+    # Exactly one of fd and file_path must be given.
+    # (If it is file_path, the helper will open that file and pass its
+    # own fd)
+    def send_fd_scm(self, fd=None, file_path=None):
+        # In iotest.py, the qmp should always use unix socket.
+        assert self._qmp.is_scm_available()
+        if self._socket_scm_helper is None:
+            raise QEMUMachineError("No path to socket_scm_helper set")
+        if not os.path.exists(self._socket_scm_helper):
+            raise QEMUMachineError("%s does not exist" %
+                                   self._socket_scm_helper)
+
+        # This did not exist before 3.4, but since then it is
+        # mandatory for our purpose
+        if hasattr(os, 'set_inheritable'):
+            os.set_inheritable(self._qmp.get_sock_fd(), True)
+            if fd is not None:
+                os.set_inheritable(fd, True)
+
+        fd_param = ["%s" % self._socket_scm_helper,
+                    "%d" % self._qmp.get_sock_fd()]
+
+        if file_path is not None:
+            assert fd is None
+            fd_param.append(file_path)
+        else:
+            assert fd is not None
+            fd_param.append(str(fd))
+
+        devnull = open(os.path.devnull, 'rb')
+        proc = subprocess.Popen(fd_param, stdin=devnull, stdout=subprocess.PIPE,
+                                stderr=subprocess.STDOUT, close_fds=False)
+        output = proc.communicate()[0]
+        if output:
+            LOG.debug(output)
+
+        return proc.returncode
+
+    @staticmethod
+    def _remove_if_exists(path):
+        """
+        Remove file object at path if it exists
+        """
+        try:
+            os.remove(path)
+        except OSError as exception:
+            if exception.errno == errno.ENOENT:
+                return
+            raise
+
+    def is_running(self):
+        return self._popen is not None and self._popen.poll() is None
+
+    def exitcode(self):
+        if self._popen is None:
+            return None
+        return self._popen.poll()
+
+    def get_pid(self):
+        if not self.is_running():
+            return None
+        return self._popen.pid
+
+    def _load_io_log(self):
+        if self._qemu_log_path is not None:
+            with open(self._qemu_log_path, "r") as iolog:
+                self._iolog = iolog.read()
+
+    def _base_args(self):
+        if isinstance(self._monitor_address, tuple):
+            moncdev = "socket,id=mon,host=%s,port=%s" % (
+                self._monitor_address[0],
+                self._monitor_address[1])
+        else:
+            moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
+        args = ['-chardev', moncdev,
+                '-mon', 'chardev=mon,mode=control',
+                '-display', 'none', '-vga', 'none']
+        if self._machine is not None:
+            args.extend(['-machine', self._machine])
+        if self._console_set:
+            self._console_address = os.path.join(self._temp_dir,
+                                                 self._name + "-console.sock")
+            chardev = ('socket,id=console,path=%s,server,nowait' %
+                       self._console_address)
+            args.extend(['-chardev', chardev])
+            if self._console_device_type is None:
+                args.extend(['-serial', 'chardev:console'])
+            else:
+                device = '%s,chardev=console' % self._console_device_type
+                args.extend(['-device', device])
+        return args
+
+    def _pre_launch(self):
+        self._temp_dir = tempfile.mkdtemp(dir=self._test_dir)
+        if self._monitor_address is not None:
+            self._vm_monitor = self._monitor_address
+        else:
+            self._vm_monitor = os.path.join(self._temp_dir,
+                                            self._name + "-monitor.sock")
+        self._qemu_log_path = os.path.join(self._temp_dir, self._name + ".log")
+        self._qemu_log_file = open(self._qemu_log_path, 'wb')
+
+        self._qmp = qmp.QEMUMonitorProtocol(self._vm_monitor,
+                                            server=True)
+
+    def _post_launch(self):
+        self._qmp.accept()
+
+    def _post_shutdown(self):
+        if self._qemu_log_file is not None:
+            self._qemu_log_file.close()
+            self._qemu_log_file = None
+
+        self._qemu_log_path = None
+
+        if self._console_socket is not None:
+            self._console_socket.close()
+            self._console_socket = None
+
+        if self._temp_dir is not None:
+            shutil.rmtree(self._temp_dir)
+            self._temp_dir = None
+
+    def launch(self):
+        """
+        Launch the VM and make sure we cleanup and expose the
+        command line/output in case of exception
+        """
+
+        if self._launched:
+            raise QEMUMachineError('VM already launched')
+
+        self._iolog = None
+        self._qemu_full_args = None
+        try:
+            self._launch()
+            self._launched = True
+        except:
+            self.shutdown()
+
+            LOG.debug('Error launching VM')
+            if self._qemu_full_args:
+                LOG.debug('Command: %r', ' '.join(self._qemu_full_args))
+            if self._iolog:
+                LOG.debug('Output: %r', self._iolog)
+            raise
+
+    def _launch(self):
+        """
+        Launch the VM and establish a QMP connection
+        """
+        devnull = open(os.path.devnull, 'rb')
+        self._pre_launch()
+        self._qemu_full_args = (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,
+                                       stdout=self._qemu_log_file,
+                                       stderr=subprocess.STDOUT,
+                                       shell=False,
+                                       close_fds=False)
+        self._post_launch()
+
+    def wait(self):
+        """
+        Wait for the VM to power off
+        """
+        self._popen.wait()
+        self._qmp.close()
+        self._load_io_log()
+        self._post_shutdown()
+
+    def shutdown(self):
+        """
+        Terminate the VM and clean up
+        """
+        if self.is_running():
+            try:
+                self._qmp.cmd('quit')
+                self._qmp.close()
+            except:
+                self._popen.kill()
+            self._popen.wait()
+
+        self._load_io_log()
+        self._post_shutdown()
+
+        exitcode = self.exitcode()
+        if exitcode is not None and exitcode < 0:
+            msg = 'qemu received signal %i: %s'
+            if self._qemu_full_args:
+                command = ' '.join(self._qemu_full_args)
+            else:
+                command = ''
+            LOG.warn(msg, -exitcode, command)
+
+        self._launched = False
+
+    def qmp(self, cmd, conv_keys=True, **args):
+        """
+        Invoke a QMP command and return the response dict
+        """
+        qmp_args = dict()
+        for key, value in args.items():
+            if conv_keys:
+                qmp_args[key.replace('_', '-')] = value
+            else:
+                qmp_args[key] = value
+
+        return self._qmp.cmd(cmd, args=qmp_args)
+
+    def command(self, cmd, conv_keys=True, **args):
+        """
+        Invoke a QMP command.
+        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 MonitorResponseError(reply)
+        return reply["return"]
+
+    def get_qmp_event(self, wait=False):
+        """
+        Poll for one queued QMP events and return it
+        """
+        if len(self._events) > 0:
+            return self._events.pop(0)
+        return self._qmp.pull_event(wait=wait)
+
+    def get_qmp_events(self, wait=False):
+        """
+        Poll for queued QMP events and return a list of dicts
+        """
+        events = self._qmp.get_events(wait=wait)
+        events.extend(self._events)
+        del self._events[:]
+        self._qmp.clear_events()
+        return events
+
+    @staticmethod
+    def event_match(event, match=None):
+        """
+        Check if an event matches optional match criteria.
+
+        The match criteria takes the form of a matching subdict. The event is
+        checked to be a superset of the subdict, recursively, with matching
+        values whenever the subdict values are not None.
+
+        This has a limitation that you cannot explicitly check for None values.
+
+        Examples, with the subdict queries on the left:
+         - None matches any object.
+         - {"foo": None} matches {"foo": {"bar": 1}}
+         - {"foo": None} matches {"foo": 5}
+         - {"foo": {"abc": None}} does not match {"foo": {"bar": 1}}
+         - {"foo": {"rab": 2}} matches {"foo": {"bar": 1, "rab": 2}}
+        """
+        if match is None:
+            return True
+
+        try:
+            for key in match:
+                if key in event:
+                    if not QEMUMachine.event_match(event[key], match[key]):
+                        return False
+                else:
+                    return False
+            return True
+        except TypeError:
+            # either match or event wasn't iterable (not a dict)
+            return match == event
+
+    def event_wait(self, name, timeout=60.0, match=None):
+        """
+        event_wait waits for and returns a named event from QMP with a timeout.
+
+        name: The event to wait for.
+        timeout: QEMUMonitorProtocol.pull_event timeout parameter.
+        match: Optional match criteria. See event_match for details.
+        """
+        return self.events_wait([(name, match)], timeout)
+
+    def events_wait(self, events, timeout=60.0):
+        """
+        events_wait waits for and returns a named event from QMP with a timeout.
+
+        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.
+        """
+        def _match(event):
+            for name, match in events:
+                if (event['event'] == name and
+                    self.event_match(event, match)):
+                    return True
+            return False
+
+        # Search cached events
+        for event in self._events:
+            if _match(event):
+                self._events.remove(event)
+                return event
+
+        # Poll for new events
+        while True:
+            event = self._qmp.pull_event(wait=timeout)
+            if _match(event):
+                return event
+            self._events.append(event)
+
+        return None
+
+    def get_log(self):
+        """
+        After self.shutdown or failed qemu execution, this returns the output
+        of the qemu process.
+        """
+        return self._iolog
+
+    def add_args(self, *args):
+        """
+        Adds to the list of extra arguments to be given to the QEMU binary
+        """
+        self._args.extend(args)
+
+    def set_machine(self, machine_type):
+        """
+        Sets the machine type
+
+        If set, the machine type will be added to the base arguments
+        of the resulting QEMU command line.
+        """
+        self._machine = machine_type
+
+    def set_console(self, device_type=None):
+        """
+        Sets the device type for a console device
+
+        If set, the console device and a backing character device will
+        be added to the base arguments of the resulting QEMU command
+        line.
+
+        This is a convenience method that will either use the provided
+        device type, or default to a "-serial chardev:console" command
+        line argument.
+
+        The actual setting of command line arguments will be be done at
+        machine launch time, as it depends on the temporary directory
+        to be created.
+
+        @param device_type: the device type, such as "isa-serial".  If
+                            None is given (the default value) a "-serial
+                            chardev:console" command line argument will
+                            be used instead, resorting to the machine's
+                            default device type.
+        """
+        self._console_set = True
+        self._console_device_type = device_type
+
+    @property
+    def console_socket(self):
+        """
+        Returns a socket connected to the console
+        """
+        if self._console_socket is None:
+            self._console_socket = socket.socket(socket.AF_UNIX,
+                                                 socket.SOCK_STREAM)
+            self._console_socket.connect(self._console_address)
+        return self._console_socket