QMP/qmp.py

   1 # QEMU Monitor Protocol Python class
   2 #
   3 # Copyright (C) 2009 Red Hat Inc.
   4 #
   5 # Authors:
   6 #  Luiz Capitulino <lcapitulino@redhat.com>
   7 #
   8 # This work is licensed under the terms of the GNU GPL, version 2.  See
   9 # the COPYING file in the top-level directory.
  10
  11 import socket, json
  12
  13 class QMPError(Exception):
  14     pass
  15
  16 class QMPConnectError(QMPError):
  17     pass
  18
  19 class QEMUMonitorProtocol:
  20     def connect(self):
  21         self.sock.connect(self.filename)
  22         data = self.__json_read()
  23         if data == None:
  24             raise QMPConnectError
  25         if not data.has_key('QMP'):
  26             raise QMPConnectError
  27         return data['QMP']['capabilities']
  28
  29     def close(self):
  30         self.sock.close()
  31
  32     def send_raw(self, line):
  33         self.sock.send(str(line))
  34         return self.__json_read()
  35
  36     def send(self, cmdline):
  37         cmd = self.__build_cmd(cmdline)
  38         self.__json_send(cmd)
  39         resp = self.__json_read()
  40         if resp == None:
  41             return
  42         elif resp.has_key('error'):
  43             return resp['error']
  44         else:
  45             return resp['return']
  46
  47     def __build_cmd(self, cmdline):
  48         cmdargs = cmdline.split()
  49         qmpcmd = { 'execute': cmdargs[0], 'arguments': {} }
  50         for arg in cmdargs[1:]:
  51             opt = arg.split('=')
  52             try:
  53                 value = int(opt[1])
  54             except ValueError:
  55                 value = opt[1]
  56             qmpcmd['arguments'][opt[0]] = value
  57         return qmpcmd
  58
  59     def __json_send(self, cmd):
  60         # XXX: We have to send any additional char, otherwise
  61         # the Server won't read our input
  62         self.sock.send(json.dumps(cmd) + ' ')
  63
  64     def __json_read(self):
  65         try:
  66             while True:
  67                 line = json.loads(self.sockfile.readline())
  68                 if not 'event' in line:
  69                     return line
  70         except ValueError:
  71             return
  72
  73     def __init__(self, filename):
  74         self.filename = filename
  75         self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
  76         self.sockfile = self.sock.makefile()