am 706747e5: Merge "libsysutils: Fix wait loop in ServiceManager::start and ::stop" into honeycomb (bc8facc9) · Commits · e / os / android_system_core

libsysutils/src/ServiceManager.cpp

+54 −12

Original line number	Diff line number	Diff line
		@@ -10,7 +10,39 @@
		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;
		@@ -19,13 +51,14 @@ int ServiceManager::start(const char *name) {
		SLOGD("Starting service '%s'", name);
		property_set("ctl.start", name);

		int count = 200;
		while(count--) {
		sched_yield();
		int count = SLEEP_MAX_USEC;
		while(count > 0) {
		usleep(SLEEP_MIN_USEC);
		count -= SLEEP_MIN_USEC;
		if (isRunning(name))
		break;
		}
		if (!count) {
		if (count <= 0) {
		SLOGW("Timed out waiting for service '%s' to start", name);
		errno = ETIMEDOUT;
		return -1;
		@@ -35,6 +68,10 @@ int ServiceManager::start(const char *name) {
		}

		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;
		@@ -43,28 +80,33 @@ int ServiceManager::stop(const char *name) {
		SLOGD("Stopping service '%s'", name);
		property_set("ctl.stop", name);

		int count = 200;
		while(count--) {
		sched_yield();
		int count = SLEEP_MAX_USEC;
		while(count > 0) {
		usleep(SLEEP_MIN_USEC);
		count -= SLEEP_MIN_USEC;
		if (!isRunning(name))
		break;
		}

		if (!count) {
		if (count <= 0) {
		SLOGW("Timed out waiting for service '%s' to stop", name);
		errno = ETIMEDOUT;
		return -1;
		}
		SLOGD("Sucessfully stopped '%s'", name);
		SLOGD("Successfully stopped '%s'", name);
		return 0;
		}

		bool ServiceManager::isRunning(const char *name) {
		char propVal[PROPERTY_VALUE_MAX];
		char propName[255];

		snprintf(propName, sizeof(propVal), "init.svc.%s", name);
		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"))