QMP: Introduce qmp-shell

This is a very simple shell written in Python for demonstration
purposes.

Unfortunately it's a bit awkward right now, as the user has
to specify the arguments names and the printed data can be
a raw dictionary or list, like the following example:

(QEMU) pci_add pci_addr=auto type=nic
{u'slot': 5, u'bus': 0, u'domain': 0, u'function': 0}
(QEMU)

It's worth to note that the shell is broken into two files.
One is the shell itself, the other is the QMP class which
handles the communication with QEMU.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

QMP/qmp-shell

@@ -0,0 +1,72 @@
+#!/usr/bin/python
+#
+# Simple QEMU shell on top of QMP
+#
+# Copyright (C) 2009 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.
+#
+# Usage:
+#
+# Start QEMU with:
+#
+# $ qemu [...] -monitor control,unix:./qmp,server
+#
+# Run the shell:
+#
+# $ qmp-shell ./qmp
+#
+# Commands have the following format:
+#
+# < command-name > [ arg-name1=arg1 ] ... [ arg-nameN=argN ]
+#
+# For example:
+#
+# (QEMU) info item=network
+
+import qmp
+import readline
+from sys import argv,exit
+
+def shell_help():
+    print 'bye  exit from the shell'
+
+def main():
+    if len(argv) != 2:
+        print 'qemu-shell <unix-socket>'
+        exit(1)
+
+    qemu = qmp.QEMUMonitorProtocol(argv[1])
+    qemu.connect()
+
+    print 'Connected!'
+
+    while True:
+        try:
+            cmd = raw_input('(QEMU) ')
+        except EOFError:
+            print
+            break
+        if cmd == '':
+            continue
+        elif cmd == 'bye':
+            break
+        elif cmd == 'help':
+            shell_help()
+        else:
+            try:
+                resp = qemu.send(cmd)
+                if resp == None:
+                    print 'Disconnected'
+                    break
+                print resp
+            except IndexError:
+                print '-> command format: <command-name> ',
+                print '[arg-name1=arg1] ... [arg-nameN=argN]'
+
+if __name__ == '__main__':
+    main()

QMP/qmp.py

@@ -0,0 +1,72 @@
+# QEMU Monitor Protocol Python class
+# 
+# Copyright (C) 2009 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 socket, json
+
+class QMPError(Exception):
+    pass
+
+class QMPConnectError(QMPError):
+    pass
+
+class QEMUMonitorProtocol:
+    def connect(self):
+        self.sock.connect(self.filename)
+        data = self.__json_read()
+        if data == None:
+            raise QMPConnectError
+        if not data.has_key('QMP'):
+            raise QMPConnectError
+        return data['QMP']['capabilities']
+
+    def close(self):
+        self.sock.close()
+
+    def send_raw(self, line):
+        self.sock.send(str(line))
+        return self.__json_read()
+
+    def send(self, cmdline):
+        cmd = self.__build_cmd(cmdline)
+        self.__json_send(cmd)
+        resp = self.__json_read()
+        if resp == None:
+            return
+        elif resp.has_key('error'):
+            return resp['error']
+        else:
+            return resp['return']
+
+    def __build_cmd(self, cmdline):
+        cmdargs = cmdline.split()
+        qmpcmd = { 'execute': cmdargs[0], 'arguments': {} }
+        for arg in cmdargs[1:]:
+            opt = arg.split('=')
+            try:
+                value = int(opt[1])
+            except ValueError:
+                value = opt[1]
+            qmpcmd['arguments'][opt[0]] = value
+        return qmpcmd
+
+    def __json_send(self, cmd):
+        # XXX: We have to send any additional char, otherwise
+        # the Server won't read our input
+        self.sock.send(json.dumps(cmd) + ' ')
+
+    def __json_read(self):
+        try:
+            return json.loads(self.sock.recv(1024))
+        except ValueError:
+            return
+
+    def __init__(self, filename):
+        self.filename = filename
+        self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)