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/*
* Copyright (C) 2009-2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "Service"
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <cutils/properties.h>
#include <log/log.h>
#include <sysutils/ServiceManager.h>
ServiceManager::ServiceManager() {
}
/* The service name should not exceed SERVICE_NAME_MAX to avoid
* some weird things. This is due to the fact that:
*
* - Starting a service is done by writing its name to the "ctl.start"
* system property. This triggers the init daemon to actually start
* the service for us.
*
* - Stopping the service is done by writing its name to "ctl.stop"
* in a similar way.
*
* - Reading the status of a service is done by reading the property
* named "init.svc.<name>"
*
* If strlen(<name>) > (PROPERTY_KEY_MAX-1)-9, then you can start/stop
* the service by writing to ctl.start/stop, but you won't be able to
* read its state due to the truncation of "init.svc.<name>" into a
* zero-terminated buffer of PROPERTY_KEY_MAX characters.
*/
#define SERVICE_NAME_MAX (PROPERTY_KEY_MAX-10)
/* The maximum amount of time to wait for a service to start or stop,
* in micro-seconds (really an approximation) */
#define SLEEP_MAX_USEC 2000000 /* 2 seconds */
/* The minimal sleeping interval between checking for the service's state
* when looping for SLEEP_MAX_USEC */
#define SLEEP_MIN_USEC 200000 /* 200 msec */
int ServiceManager::start(const char *name) {
if (strlen(name) > SERVICE_NAME_MAX) {
SLOGE("Service name '%s' is too long", name);
return 0;
}
if (isRunning(name)) {
SLOGW("Service '%s' is already running", name);
return 0;
}
SLOGD("Starting service '%s'", name);
property_set("ctl.start", name);
int count = SLEEP_MAX_USEC;
while(count > 0) {
usleep(SLEEP_MIN_USEC);
count -= SLEEP_MIN_USEC;
if (isRunning(name))
break;
}
if (count <= 0) {
SLOGW("Timed out waiting for service '%s' to start", name);
errno = ETIMEDOUT;
return -1;
}
SLOGD("Sucessfully started '%s'", name);
return 0;
}
int ServiceManager::stop(const char *name) {
if (strlen(name) > SERVICE_NAME_MAX) {
SLOGE("Service name '%s' is too long", name);
return 0;
}
if (!isRunning(name)) {
SLOGW("Service '%s' is already stopped", name);
return 0;
}
SLOGD("Stopping service '%s'", name);
property_set("ctl.stop", name);
int count = SLEEP_MAX_USEC;
while(count > 0) {
usleep(SLEEP_MIN_USEC);
count -= SLEEP_MIN_USEC;
if (!isRunning(name))
break;
}
if (count <= 0) {
SLOGW("Timed out waiting for service '%s' to stop", name);
errno = ETIMEDOUT;
return -1;
}
SLOGD("Successfully stopped '%s'", name);
return 0;
}
bool ServiceManager::isRunning(const char *name) {
char propVal[PROPERTY_VALUE_MAX];
char propName[PROPERTY_KEY_MAX];
int ret;
ret = snprintf(propName, sizeof(propName), "init.svc.%s", name);
if (ret > (int)sizeof(propName)-1) {
SLOGD("Service name '%s' is too long", name);
return false;
}
if (property_get(propName, propVal, NULL)) {
if (!strcmp(propVal, "running"))
return true;
}
return false;
}
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