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# QEMU Monitor Protocol Python class
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#
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# Copyright (C) 2009, 2010 Red Hat Inc.
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#
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# Authors:
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# Luiz Capitulino <lcapitulino@redhat.com>
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#
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# This work is licensed under the terms of the GNU GPL, version 2. See
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# the COPYING file in the top-level directory.
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import json |
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import errno |
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import socket |
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class QMPError(Exception): |
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pass
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class QMPConnectError(QMPError): |
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pass
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class QMPCapabilitiesError(QMPError): |
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pass
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class QEMUMonitorProtocol: |
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def __init__(self, address, server=False): |
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"""
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Create a QEMUMonitorProtocol class.
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@param address: QEMU address, can be either a unix socket path (string)
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or a tuple in the form ( address, port ) for a TCP
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connection
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@param server: server mode listens on the socket (bool)
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@raise socket.error on socket connection errors
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@note No connection is established, this is done by the connect() or
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accept() methods
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"""
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self.__events = []
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self.__address = address
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self.__sock = self.__get_sock() |
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if server:
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self.__sock.bind(self.__address) |
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self.__sock.listen(1) |
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def __get_sock(self): |
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if isinstance(self.__address, tuple): |
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family = socket.AF_INET |
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else:
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family = socket.AF_UNIX |
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return socket.socket(family, socket.SOCK_STREAM)
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def __negotiate_capabilities(self): |
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self.__sockfile = self.__sock.makefile() |
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greeting = self.__json_read()
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if greeting is None or not greeting.has_key('QMP'): |
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raise QMPConnectError
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# Greeting seems ok, negotiate capabilities
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resp = self.cmd('qmp_capabilities') |
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if "return" in resp: |
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return greeting
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raise QMPCapabilitiesError
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def __json_read(self, only_event=False): |
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while True: |
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data = self.__sockfile.readline()
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if not data: |
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return
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resp = json.loads(data) |
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if 'event' in resp: |
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self.__events.append(resp)
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if not only_event: |
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continue
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return resp
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error = socket.error |
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def connect(self): |
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"""
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Connect to the QMP Monitor and perform capabilities negotiation.
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@return QMP greeting dict
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@raise socket.error on socket connection errors
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@raise QMPConnectError if the greeting is not received
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@raise QMPCapabilitiesError if fails to negotiate capabilities
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"""
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self.__sock.connect(self.__address) |
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return self.__negotiate_capabilities() |
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def accept(self): |
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"""
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Await connection from QMP Monitor and perform capabilities negotiation.
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@return QMP greeting dict
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@raise socket.error on socket connection errors
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@raise QMPConnectError if the greeting is not received
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@raise QMPCapabilitiesError if fails to negotiate capabilities
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"""
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self.__sock, _ = self.__sock.accept() |
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return self.__negotiate_capabilities() |
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def cmd_obj(self, qmp_cmd): |
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"""
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Send a QMP command to the QMP Monitor.
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@param qmp_cmd: QMP command to be sent as a Python dict
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@return QMP response as a Python dict or None if the connection has
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been closed
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"""
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try:
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self.__sock.sendall(json.dumps(qmp_cmd))
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except socket.error, err:
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if err[0] == errno.EPIPE: |
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return
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raise socket.error(err)
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return self.__json_read() |
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def cmd(self, name, args=None, id=None): |
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"""
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Build a QMP command and send it to the QMP Monitor.
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@param name: command name (string)
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@param args: command arguments (dict)
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@param id: command id (dict, list, string or int)
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"""
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qmp_cmd = { 'execute': name }
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if args:
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qmp_cmd['arguments'] = args
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if id: |
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qmp_cmd['id'] = id |
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return self.cmd_obj(qmp_cmd) |
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def get_events(self, wait=False): |
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"""
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Get a list of available QMP events.
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@param wait: block until an event is available (bool)
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"""
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self.__sock.setblocking(0) |
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try:
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self.__json_read()
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except socket.error, err:
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if err[0] == errno.EAGAIN: |
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# No data available
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pass
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self.__sock.setblocking(1) |
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if not self.__events and wait: |
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self.__json_read(only_event=True) |
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return self.__events |
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def clear_events(self): |
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"""
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Clear current list of pending events.
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"""
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self.__events = []
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def close(self): |
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self.__sock.close()
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self.__sockfile.close()
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