1 /*
2 * Copyright (C) 2009-2016 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 #define LOG_TAG "Service"
18
19 #include <errno.h>
20 #include <stdio.h>
21 #include <string.h>
22 #include <sys/system_properties.h>
23 #include <unistd.h>
24
25 #include <android-base/properties.h>
26 #include <android-base/stringprintf.h>
27 #include <log/log.h>
28 #include <sysutils/ServiceManager.h>
29
ServiceManager()30 ServiceManager::ServiceManager() {
31 }
32
33 // The length of a service name should not exceed SERVICE_NAME_MAX. Starting
34 // a service is done by writing its name to the "ctl.start" system property
35 // and stopping a service is done by writing its name to "ctl.stop". If a
36 // service name is too long to fit in a property, you won't be able to start
37 // or stop it.
38 static constexpr size_t SERVICE_NAME_MAX = PROP_VALUE_MAX;
39
40 /* The maximum amount of time to wait for a service to start or stop,
41 * in micro-seconds (really an approximation) */
42 #define SLEEP_MAX_USEC 2000000 /* 2 seconds */
43
44 /* The minimal sleeping interval between checking for the service's state
45 * when looping for SLEEP_MAX_USEC */
46 #define SLEEP_MIN_USEC 200000 /* 200 msec */
47
start(const char * name)48 int ServiceManager::start(const char *name) {
49 if (strlen(name) > SERVICE_NAME_MAX) {
50 SLOGE("Service name '%s' is too long", name);
51 return 0;
52 }
53
54 if (isRunning(name)) {
55 SLOGW("Service '%s' is already running", name);
56 return 0;
57 }
58
59 SLOGD("Starting service '%s'", name);
60 android::base::SetProperty("ctl.start", name);
61
62 int count = SLEEP_MAX_USEC;
63 while(count > 0) {
64 usleep(SLEEP_MIN_USEC);
65 count -= SLEEP_MIN_USEC;
66 if (isRunning(name))
67 break;
68 }
69 if (count <= 0) {
70 SLOGW("Timed out waiting for service '%s' to start", name);
71 errno = ETIMEDOUT;
72 return -1;
73 }
74 SLOGD("Sucessfully started '%s'", name);
75 return 0;
76 }
77
stop(const char * name)78 int ServiceManager::stop(const char *name) {
79 if (strlen(name) > SERVICE_NAME_MAX) {
80 SLOGE("Service name '%s' is too long", name);
81 return 0;
82 }
83
84 if (!isRunning(name)) {
85 SLOGW("Service '%s' is already stopped", name);
86 return 0;
87 }
88
89 SLOGD("Stopping service '%s'", name);
90 android::base::SetProperty("ctl.stop", name);
91
92 int count = SLEEP_MAX_USEC;
93 while(count > 0) {
94 usleep(SLEEP_MIN_USEC);
95 count -= SLEEP_MIN_USEC;
96 if (!isRunning(name))
97 break;
98 }
99
100 if (count <= 0) {
101 SLOGW("Timed out waiting for service '%s' to stop", name);
102 errno = ETIMEDOUT;
103 return -1;
104 }
105 SLOGD("Successfully stopped '%s'", name);
106 return 0;
107 }
108
isRunning(const char * name)109 bool ServiceManager::isRunning(const char *name) {
110 std::string property_name = android::base::StringPrintf("init.svc.%s", name);
111 return (android::base::GetProperty(property_name, "") == "running");
112 }
113