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1#/usr/bin/env python3.4
2#
3# Copyright (C) 2009 Google Inc.
4#
5# Licensed under the Apache License, Version 2.0 (the "License"); you may not
6# use this file except in compliance with the License. You may obtain a copy of
7# the License at
8#
9# http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
13# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
14# License for the specific language governing permissions and limitations under
15# the License.
16
17"""
18JSON RPC interface to android scripting engine.
19"""
20
21from builtins import str
22
23import json
24import os
25import socket
26import threading
27import time
28
29HOST = os.environ.get('AP_HOST', None)
30PORT = os.environ.get('AP_PORT', 9999)
31
32class SL4AException(Exception):
33    pass
34
35class SL4AAPIError(SL4AException):
36    """Raised when remote API reports an error."""
37
38class SL4AProtocolError(SL4AException):
39    """Raised when there is some error in exchanging data with server on device."""
40    NO_RESPONSE_FROM_HANDSHAKE = "No response from handshake."
41    NO_RESPONSE_FROM_SERVER = "No response from server."
42    MISMATCHED_API_ID = "Mismatched API id."
43
44def IDCounter():
45    i = 0
46    while True:
47        yield i
48        i += 1
49
50class Android(object):
51    COUNTER = IDCounter()
52
53    _SOCKET_CONNECT_TIMEOUT = 60
54
55    def __init__(self, cmd='initiate', uid=-1, port=PORT, addr=HOST, timeout=None):
56        self.lock = threading.RLock()
57        self.client = None  # prevent close errors on connect failure
58        self.uid = None
59        timeout_time = time.time() + self._SOCKET_CONNECT_TIMEOUT
60        while True:
61            try:
62                self.conn = socket.create_connection(
63                        (addr, port), max(1,timeout_time - time.time()))
64                self.conn.settimeout(timeout)
65                break
66            except (TimeoutError, socket.timeout):
67                print("Failed to create socket connection!")
68                raise
69            except (socket.error, IOError):
70                # TODO: optimize to only forgive some errors here
71                # error values are OS-specific so this will require
72                # additional tuning to fail faster
73                if time.time() + 1 >= timeout_time:
74                    print("Failed to create socket connection!")
75                    raise
76                time.sleep(1)
77
78        self.client = self.conn.makefile(mode="brw")
79
80        resp = self._cmd(cmd, uid)
81        if not resp:
82            raise SL4AProtocolError(SL4AProtocolError.NO_RESPONSE_FROM_HANDSHAKE)
83        result = json.loads(str(resp, encoding="utf8"))
84        if result['status']:
85            self.uid = result['uid']
86        else:
87            self.uid = -1
88
89    def close(self):
90        if self.conn is not None:
91            self.conn.close()
92            self.conn = None
93
94    def _cmd(self, command, uid=None):
95        if not uid:
96            uid = self.uid
97        self.client.write(
98            json.dumps({'cmd': command, 'uid': uid})
99                .encode("utf8")+b'\n')
100        self.client.flush()
101        return self.client.readline()
102
103    def _rpc(self, method, *args):
104        self.lock.acquire()
105        apiid = next(Android.COUNTER)
106        self.lock.release()
107        data = {'id': apiid,
108                'method': method,
109                'params': args}
110        request = json.dumps(data)
111        self.client.write(request.encode("utf8")+b'\n')
112        self.client.flush()
113        response = self.client.readline()
114        if not response:
115            raise SL4AProtocolError(SL4AProtocolError.NO_RESPONSE_FROM_SERVER)
116        result = json.loads(str(response, encoding="utf8"))
117        if result['error']:
118            raise SL4AAPIError(result['error'])
119        if result['id'] != apiid:
120            raise SL4AProtocolError(SL4AProtocolError.MISMATCHED_API_ID)
121        return result['result']
122
123    def __getattr__(self, name):
124        def rpc_call(*args):
125            return self._rpc(name, *args)
126        return rpc_call
127