1 /*
2  * Copyright (C) 2016 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "wifi_system/supplicant_manager.h"
18 
19 #include <android-base/logging.h>
20 #include <cutils/properties.h>
21 #include <fcntl.h>
22 #include <string.h>
23 #include <sys/stat.h>
24 #include <unistd.h>
25 
26 // This ugliness is necessary to access internal implementation details
27 // of the property subsystem.
28 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
29 #include <sys/_system_properties.h>
30 
31 namespace android {
32 namespace wifi_system {
33 namespace {
34 
35 const char kSupplicantInitProperty[] = "init.svc.wpa_supplicant";
36 const char kSupplicantServiceName[] = "wpa_supplicant";
37 
38 }  // namespace
39 
40 bool SupplicantManager::StartSupplicant() {
41   char supp_status[PROPERTY_VALUE_MAX] = {'\0'};
42   int count = 200; /* wait at most 20 seconds for completion */
43   const prop_info* pi;
44   unsigned serial = 0;
45 
46   /* Check whether already running */
47   if (property_get(kSupplicantInitProperty, supp_status, NULL) &&
48       strcmp(supp_status, "running") == 0) {
49     return true;
50   }
51 
52   /*
53    * Get a reference to the status property, so we can distinguish
54    * the case where it goes stopped => running => stopped (i.e.,
55    * it start up, but fails right away) from the case in which
56    * it starts in the stopped state and never manages to start
57    * running at all.
58    */
59   pi = __system_property_find(kSupplicantInitProperty);
60   if (pi != NULL) {
61     serial = __system_property_serial(pi);
62   }
63 
64   property_set("ctl.start", kSupplicantServiceName);
65   sched_yield();
66 
67   while (count-- > 0) {
68     if (pi == NULL) {
69       pi = __system_property_find(kSupplicantInitProperty);
70     }
71     if (pi != NULL) {
72       /*
73        * property serial updated means that init process is scheduled
74        * after we sched_yield, further property status checking is based on this
75        */
76       if (__system_property_serial(pi) != serial) {
77         __system_property_read(pi, NULL, supp_status);
78         if (strcmp(supp_status, "running") == 0) {
79           return true;
80         } else if (strcmp(supp_status, "stopped") == 0) {
81           return false;
82         }
83       }
84     }
85     usleep(100000);
86   }
87   return false;
88 }
89 
90 bool SupplicantManager::StopSupplicant() {
91   char supp_status[PROPERTY_VALUE_MAX] = {'\0'};
92   int count = 200; /* wait at most 20 seconds for completion */
93 
94   /* Check whether supplicant already stopped */
95   if (property_get(kSupplicantInitProperty, supp_status, NULL) &&
96       strcmp(supp_status, "stopped") == 0) {
97     return true;
98   }
99 
100   property_set("ctl.stop", kSupplicantServiceName);
101   sched_yield();
102 
103   while (count-- > 0) {
104     if (property_get(kSupplicantInitProperty, supp_status, NULL)) {
105       if (strcmp(supp_status, "stopped") == 0) return true;
106     }
107     usleep(100000);
108   }
109   LOG(ERROR) << "Failed to stop supplicant";
110   return false;
111 }
112 
113 bool SupplicantManager::IsSupplicantRunning() {
114   char supp_status[PROPERTY_VALUE_MAX] = {'\0'};
115   if (property_get(kSupplicantInitProperty, supp_status, NULL)) {
116     return strcmp(supp_status, "running") == 0;
117   }
118   return false;  // Failed to read service status from init.
119 }
120 
121 }  // namespace wifi_system
122 }  // namespace android
123