--- /dev/null
+# QEMU Monitor Protocol Python class
+#
+# Copyright (C) 2009, 2010 Red Hat Inc.
+#
+# Authors:
+# Luiz Capitulino <lcapitulino@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2. See
+# the COPYING file in the top-level directory.
+
+import json
+import errno
+import socket
+
+class QMPError(Exception):
+ pass
+
+class QMPConnectError(QMPError):
+ pass
+
+class QMPCapabilitiesError(QMPError):
+ pass
+
+class QMPTimeoutError(QMPError):
+ pass
+
+class QEMUMonitorProtocol:
+ def __init__(self, address, server=False):
+ """
+ Create a QEMUMonitorProtocol class.
+
+ @param address: QEMU address, can be either a unix socket path (string)
+ or a tuple in the form ( address, port ) for a TCP
+ connection
+ @param server: server mode listens on the socket (bool)
+ @raise socket.error on socket connection errors
+ @note No connection is established, this is done by the connect() or
+ accept() methods
+ """
+ self.__events = []
+ self.__address = address
+ self.__sock = self.__get_sock()
+ if server:
+ self.__sock.bind(self.__address)
+ self.__sock.listen(1)
+
+ def __get_sock(self):
+ 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):
+ greeting = self.__json_read()
+ if greeting is None or not greeting.has_key('QMP'):
+ raise QMPConnectError
+ # Greeting seems ok, negotiate capabilities
+ resp = self.cmd('qmp_capabilities')
+ if "return" in resp:
+ return greeting
+ raise QMPCapabilitiesError
+
+ def __json_read(self, only_event=False):
+ while True:
+ data = self.__sockfile.readline()
+ if not data:
+ return
+ resp = json.loads(data)
+ if 'event' in resp:
+ self.__events.append(resp)
+ if not only_event:
+ continue
+ return resp
+
+ error = socket.error
+
+ def __get_events(self, wait=False):
+ """
+ Check for new events in the stream and cache them in __events.
+
+ @param wait (bool): block until an event is available.
+ @param wait (float): If wait is a float, treat it as a timeout value.
+
+ @raise QMPTimeoutError: If a timeout float is provided and the timeout
+ period elapses.
+ @raise QMPConnectError: If wait is True but no events could be retrieved
+ or if some other error occurred.
+ """
+
+ # Check for new events regardless and pull them into the cache:
+ self.__sock.setblocking(0)
+ try:
+ self.__json_read()
+ except socket.error, err:
+ if err[0] == errno.EAGAIN:
+ # No data available
+ pass
+ self.__sock.setblocking(1)
+
+ # Wait for new events, if needed.
+ # if wait is 0.0, this means "no wait" and is also implicitly false.
+ if not self.__events and wait:
+ if isinstance(wait, float):
+ self.__sock.settimeout(wait)
+ try:
+ ret = self.__json_read(only_event=True)
+ except socket.timeout:
+ raise QMPTimeoutError("Timeout waiting for event")
+ except:
+ raise QMPConnectError("Error while reading from socket")
+ if ret is None:
+ raise QMPConnectError("Error while reading from socket")
+ self.__sock.settimeout(None)
+
+ def connect(self, negotiate=True):
+ """
+ Connect to the QMP Monitor and perform capabilities negotiation.
+
+ @return QMP greeting dict
+ @raise socket.error on socket connection errors
+ @raise QMPConnectError if the greeting is not received
+ @raise QMPCapabilitiesError if fails to negotiate capabilities
+ """
+ self.__sock.connect(self.__address)
+ self.__sockfile = self.__sock.makefile()
+ if negotiate:
+ return self.__negotiate_capabilities()
+
+ def accept(self):
+ """
+ Await connection from QMP Monitor and perform capabilities negotiation.
+
+ @return QMP greeting dict
+ @raise socket.error on socket connection errors
+ @raise QMPConnectError if the greeting is not received
+ @raise QMPCapabilitiesError if fails to negotiate capabilities
+ """
+ self.__sock, _ = self.__sock.accept()
+ self.__sockfile = self.__sock.makefile()
+ return self.__negotiate_capabilities()
+
+ def cmd_obj(self, qmp_cmd):
+ """
+ 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
+ """
+ try:
+ self.__sock.sendall(json.dumps(qmp_cmd))
+ except socket.error, err:
+ if err[0] == errno.EPIPE:
+ return
+ raise socket.error(err)
+ return self.__json_read()
+
+ def cmd(self, name, args=None, id=None):
+ """
+ Build a QMP command and send it to the QMP Monitor.
+
+ @param name: command name (string)
+ @param args: command arguments (dict)
+ @param id: command id (dict, list, string or int)
+ """
+ qmp_cmd = { 'execute': name }
+ if args:
+ qmp_cmd['arguments'] = args
+ if id:
+ qmp_cmd['id'] = id
+ return self.cmd_obj(qmp_cmd)
+
+ def command(self, cmd, **kwds):
+ ret = self.cmd(cmd, kwds)
+ if ret.has_key('error'):
+ raise Exception(ret['error']['desc'])
+ return ret['return']
+
+ def pull_event(self, wait=False):
+ """
+ Get and delete the first available QMP event.
+
+ @param wait (bool): block until an event is available.
+ @param wait (float): If wait is a float, treat it as a timeout value.
+
+ @raise QMPTimeoutError: If a timeout float is provided and the timeout
+ period elapses.
+ @raise QMPConnectError: If wait is True but no events could be retrieved
+ or if some other error occurred.
+
+ @return The first available QMP event, or None.
+ """
+ self.__get_events(wait)
+
+ if self.__events:
+ return self.__events.pop(0)
+ return None
+
+ def get_events(self, wait=False):
+ """
+ Get a list of available QMP events.
+
+ @param wait (bool): block until an event is available.
+ @param wait (float): If wait is a float, treat it as a timeout value.
+
+ @raise QMPTimeoutError: If a timeout float is provided and the timeout
+ period elapses.
+ @raise QMPConnectError: If wait is True but no events could be retrieved
+ or if some other error occurred.
+
+ @return The list of available QMP events.
+ """
+ self.__get_events(wait)
+ return self.__events
+
+ def clear_events(self):
+ """
+ Clear current list of pending events.
+ """
+ self.__events = []
+
+ def close(self):
+ self.__sock.close()
+ self.__sockfile.close()
+
+ timeout = socket.timeout
+
+ def settimeout(self, timeout):
+ self.__sock.settimeout(timeout)
+
+ def get_sock_fd(self):
+ return self.__sock.fileno()
+
+ def is_scm_available(self):
+ return self.__sock.family == socket.AF_UNIX
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