[Qemu-devel] [PATCH 4/5] scripts/qemu.py: introduce set_console() method

[Cleber Rosa <crosa@redhat.com>]

The set_console() method is intended to ease higher level use cases
that require a console device.

The amount of inteligence is limited on purpose, requiring either the
device type explicitly, or the existence of a machine (pattern)
definition.

Because of the console device type selection criteria (by machine
type), users should also be able to define that.  It'll then be used
for both '-machine' and for the console device type selection.

Users of the set_console() method will certainly be interested in
accessing the console device, and for that a console_socket property
has been added.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
---
 scripts/qemu.py      |  97 +++++++++++++++++++++++-
 scripts/test_qemu.py | 176 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 272 insertions(+), 1 deletion(-)
 create mode 100644 scripts/test_qemu.py

diff --git a/scripts/qemu.py b/scripts/qemu.py
index 7813dd45ad..89db5bc6b2 100644
--- a/scripts/qemu.py
+++ b/scripts/qemu.py
@@ -17,19 +17,41 @@ import logging
 import os
 import subprocess
 import qmp.qmp
+import re
 import shutil
+import socket
 import tempfile
 
 
 LOG = logging.getLogger(__name__)
 
 
+#: Maps machine types to the preferred console device types
+CONSOLE_DEV_TYPES = {
+    r'^clipper$': 'isa-serial',
+    r'^malta': 'isa-serial',
+    r'^(pc.*|q35.*|isapc)$': 'isa-serial',
+    r'^(40p|powernv|prep)$': 'isa-serial',
+    r'^pseries.*': 'spapr-vty',
+    r'^s390-ccw-virtio.*': 'sclpconsole',
+    }
+
+
 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.qmp.QMPError):
     '''
     Represents erroneous QMP monitor reply
@@ -91,6 +113,10 @@ class QEMUMachine(object):
         self._test_dir = test_dir
         self._temp_dir = None
         self._launched = False
+        self._machine = None
+        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()
@@ -175,9 +201,19 @@ class QEMUMachine(object):
                 self._monitor_address[1])
         else:
             moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
-        return ['-chardev', moncdev,
+        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_device_type is not None:
+            self._console_address = os.path.join(self._temp_dir,
+                                                 self._name + "-console.sock")
+            chardev = ('socket,id=console,path=%s,server,nowait' %
+                       self._console_address)
+            device = '%s,chardev=console' % self._console_device_type
+            args.extend(['-chardev', chardev, '-device', device])
+        return args
 
     def _pre_launch(self):
         self._temp_dir = tempfile.mkdtemp(dir=self._test_dir)
@@ -202,6 +238,10 @@ class QEMUMachine(object):
 
         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
@@ -365,3 +405,58 @@ class QEMUMachine(object):
         Adds to the list of extra arguments to be given to the QEMU binary
         '''
         return 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, of if not given, it will used the device type set
+        on CONSOLE_DEV_TYPES.
+
+        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"
+        @raises: QEMUMachineAddDeviceError if the device type is not given
+                 and can not be determined.
+        '''
+        if device_type is None:
+            if self._machine is None:
+                raise QEMUMachineAddDeviceError("Can not add a console device:"
+                                                " QEMU instance without a "
+                                                "defined machine type")
+            for regex, device in CONSOLE_DEV_TYPES.items():
+                if re.match(regex, self._machine):
+                    device_type = device
+                    break
+            if device_type is None:
+                raise QEMUMachineAddDeviceError("Can not add a console device:"
+                                                " no matching console device "
+                                                "type definition")
+        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
diff --git a/scripts/test_qemu.py b/scripts/test_qemu.py
new file mode 100644
index 0000000000..5e016d3751
--- /dev/null
+++ b/scripts/test_qemu.py
@@ -0,0 +1,176 @@
+import sys
+import os
+import glob
+import unittest
+import shutil
+import tempfile
+import subprocess
+
+import qemu
+import qmp.qmp
+
+
+class QEMUMachineProbeError(Exception):
+    """
+    Exception raised when a probe a fails to be deterministic
+    """
+
+
+def get_built_qemu_binaries(root_dir=None):
+    """
+    Attempts to find QEMU binaries in a tree
+
+    If root_dir is None, it will attempt to find the binaries at the
+    source tree.  It's possible to override it by setting the environment
+    variable QEMU_ROOT_DIR.
+    """
+    if root_dir is None:
+        src_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+        root_dir = os.environ.get("QEMU_ROOT_DIR", src_dir)
+    binaries = glob.glob(os.path.join(root_dir, '*-softmmu/qemu-system-*'))
+    if 'win' in sys.platform:
+        bin_filter = lambda x: x.endswith(".exe")
+    else:
+        bin_filter = lambda x: not x.endswith(".exe")
+    return [_ for _ in binaries if bin_filter(_)]
+
+
+def subprocess_dev_null(mode='w'):
+    """
+    A portable null file object suitable for use with the subprocess module
+    """
+    if hasattr(subprocess, 'DEVNULL'):
+        return subprocess.DEVNULL
+    else:
+        return open(os.path.devnull, mode)
+
+
+def qmp_execute(binary_path, qmp_command):
+    """
+    Executes a QMP command on a given QEMU binary
+
+    Useful for one-off execution of QEMU binaries to get runtime
+    information.
+
+    @param binary_path: path to a QEMU binary
+    @param qmp_command: the QMP command
+    @note: passing arguments to the QMP command is not supported at
+           this time.
+    """
+    try:
+        tempdir = tempfile.mkdtemp()
+        monitor_socket = os.path.join(tempdir, 'monitor.sock')
+        args = [binary_path, '-nodefaults', '-machine', 'none',
+                '-nographic', '-S', '-qmp', 'unix:%s' % monitor_socket]
+        monitor = qmp.qmp.QEMUMonitorProtocol(monitor_socket, True)
+        try:
+            qemu_proc = subprocess.Popen(args,
+                                         stdin=subprocess.PIPE,
+                                         stdout=subprocess.PIPE,
+                                         stderr=subprocess_dev_null(),
+                                         universal_newlines=True)
+        except OSError:
+            return None
+        monitor.accept()
+        res = monitor.cmd(qmp_command)
+        monitor.cmd("quit")
+        qemu_proc.wait()
+        monitor.close()
+        return res.get("return", None)
+    finally:
+        shutil.rmtree(tempdir)
+
+
+def qemu_bin_probe_arch(binary_path):
+    """
+    Probes the architecture from the QEMU binary
+
+    @returns: either the probed arch or None
+    @rtype: str or None
+    @raises: QEMUMachineProbeError
+    """
+    res = qmp_execute(binary_path, "query-target")
+    if res is None:
+        raise QEMUMachineProbeError('Failed to probe the QEMU arch by querying'
+                                    ' the target of binary "%s"' % binary_path)
+    return res.get("arch", None)
+
+
+class QEMU(unittest.TestCase):
+
+
+    TEST_ARCH_MACHINE_CONSOLES = {
+        'alpha': ['clipper'],
+        'mips': ['malta'],
+        'x86_64': ['isapc',
+                   'pc', 'pc-0.10', 'pc-0.11', 'pc-0.12', 'pc-0.13',
+                   'pc-0.14', 'pc-0.15', 'pc-1.0', 'pc-1.1', 'pc-1.2',
+                   'pc-1.3',
+                   'pc-i440fx-1.4', 'pc-i440fx-1.5', 'pc-i440fx-1.6',
+                   'pc-i440fx-1.7', 'pc-i440fx-2.0', 'pc-i440fx-2.1',
+                   'pc-i440fx-2.10', 'pc-i440fx-2.11', 'pc-i440fx-2.2',
+                   'pc-i440fx-2.3', 'pc-i440fx-2.4', 'pc-i440fx-2.5',
+                   'pc-i440fx-2.6', 'pc-i440fx-2.7', 'pc-i440fx-2.8',
+                   'pc-i440fx-2.9', 'pc-q35-2.10', 'pc-q35-2.11',
+                   'q35', 'pc-q35-2.4', 'pc-q35-2.5', 'pc-q35-2.6',
+                   'pc-q35-2.7', 'pc-q35-2.8', 'pc-q35-2.9'],
+        'ppc64': ['40p', 'powernv', 'prep', 'pseries', 'pseries-2.1',
+                  'pseries-2.2', 'pseries-2.3', 'pseries-2.4', 'pseries-2.5',
+                  'pseries-2.6', 'pseries-2.7', 'pseries-2.8', 'pseries-2.9',
+                  'pseries-2.10', 'pseries-2.11', 'pseries-2.12'],
+        's390x': ['s390-ccw-virtio', 's390-ccw-virtio-2.4',
+                  's390-ccw-virtio-2.5', 's390-ccw-virtio-2.6',
+                  's390-ccw-virtio-2.7', 's390-ccw-virtio-2.8',
+                  's390-ccw-virtio-2.9', 's390-ccw-virtio-2.10',
+                  's390-ccw-virtio-2.11', 's390-ccw-virtio-2.12']
+    }
+
+
+    def test_set_console(self):
+        for machines in QEMU.TEST_ARCH_MACHINE_CONSOLES.values():
+            for machine in machines:
+                qemu_machine = qemu.QEMUMachine('/fake/path/to/binary')
+                qemu_machine.set_machine(machine)
+                qemu_machine.set_console()
+
+    def test_set_console_no_machine(self):
+        qemu_machine = qemu.QEMUMachine('/fake/path/to/binary')
+        self.assertRaises(qemu.QEMUMachineAddDeviceError,
+                          qemu_machine.set_console)
+
+    def test_set_console_no_machine_match(self):
+        qemu_machine = qemu.QEMUMachine('/fake/path/to/binary')
+        qemu_machine.set_machine('unknown-machine-model')
+        self.assertRaises(qemu.QEMUMachineAddDeviceError,
+                          qemu_machine.set_console)
+
+    @unittest.skipUnless(get_built_qemu_binaries(),
+                         "Could not find any QEMU binaries built to use on "
+                         "console check")
+    def test_set_console_launch(self):
+        for binary in get_built_qemu_binaries():
+            probed_arch = qemu_bin_probe_arch(binary)
+            for machine in QEMU.TEST_ARCH_MACHINE_CONSOLES.get(probed_arch, []):
+                qemu_machine = qemu.QEMUMachine(binary)
+
+                # the following workarounds are target specific required for
+                # this test.  users are of QEMUMachine are expected to deal with
+                # target specific requirements just the same in their own code
+                cap_htm_off = ('pseries-2.7', 'pseries-2.8', 'pseries-2.9',
+                               'pseries-2.10', 'pseries-2.11', 'pseries-2.12')
+                if probed_arch == 'ppc64' and machine in cap_htm_off:
+                    qemu_machine._machine = machine   # pylint: disable=W0212
+                    qemu_machine.args.extend(['-machine',
+                                              '%s,cap-htm=off' % machine])
+                elif probed_arch == 's390x':
+                    qemu_machine.set_machine(machine)
+                    qemu_machine.args.append('-nodefaults')
+                elif probed_arch == 'mips':
+                    qemu_machine.set_machine(machine)
+                    qemu_machine.args.extend(['-bios', os.path.devnull])
+                else:
+                    qemu_machine.set_machine(machine)
+
+                qemu_machine.set_console()
+                qemu_machine.launch()
+                qemu_machine.shutdown()
-- 
2.17.0