added qmp.py (from qemu projecy)

Author: [email protected]

lib/qmp.py

@@ -0,0 +1,169 @@
+# QEMU Monitor Protocol Python class
+# 
+# Copyright (C) 2009, 2010 Red Hat Inc.
+#
+# Authors:
+#  Luiz Capitulino <[email protected]>
+#
+# 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 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 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()
+        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 get_events(self, wait=False):
+        """
+        Get a list of available QMP events.
+
+        @param wait: block until an event is available (bool)
+        """
+        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)
+        if not self.__events and wait:
+            self.__json_read(only_event=True)
+        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)