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      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 = 50; /* wait at most 5 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