116 lines
3.2 KiB
C++
116 lines
3.2 KiB
C++
#include <errno.h>
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#include <string.h>
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#include <sysutils/ServiceManager.h>
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#define LOG_TAG "Service"
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#include <cutils/log.h>
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#include <cutils/properties.h>
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ServiceManager::ServiceManager() {
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}
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/* The service name should not exceed SERVICE_NAME_MAX to avoid
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* some weird things. This is due to the fact that:
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*
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* - Starting a service is done by writing its name to the "ctl.start"
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* system property. This triggers the init daemon to actually start
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* the service for us.
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*
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* - Stopping the service is done by writing its name to "ctl.stop"
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* in a similar way.
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*
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* - Reading the status of a service is done by reading the property
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* named "init.svc.<name>"
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*
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* If strlen(<name>) > (PROPERTY_KEY_MAX-1)-9, then you can start/stop
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* the service by writing to ctl.start/stop, but you won't be able to
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* read its state due to the truncation of "init.svc.<name>" into a
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* zero-terminated buffer of PROPERTY_KEY_MAX characters.
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*/
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#define SERVICE_NAME_MAX (PROPERTY_KEY_MAX-10)
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/* The maximum amount of time to wait for a service to start or stop,
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* in micro-seconds (really an approximation) */
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#define SLEEP_MAX_USEC 2000000 /* 2 seconds */
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/* The minimal sleeping interval between checking for the service's state
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* when looping for SLEEP_MAX_USEC */
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#define SLEEP_MIN_USEC 200000 /* 200 msec */
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int ServiceManager::start(const char *name) {
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if (strlen(name) > SERVICE_NAME_MAX) {
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SLOGE("Service name '%s' is too long", name);
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return 0;
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}
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if (isRunning(name)) {
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SLOGW("Service '%s' is already running", name);
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return 0;
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}
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SLOGD("Starting service '%s'", name);
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property_set("ctl.start", name);
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int count = SLEEP_MAX_USEC;
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while(count > 0) {
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usleep(SLEEP_MIN_USEC);
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count -= SLEEP_MIN_USEC;
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if (isRunning(name))
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break;
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}
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if (count <= 0) {
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SLOGW("Timed out waiting for service '%s' to start", name);
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errno = ETIMEDOUT;
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return -1;
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}
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SLOGD("Sucessfully started '%s'", name);
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return 0;
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}
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int ServiceManager::stop(const char *name) {
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if (strlen(name) > SERVICE_NAME_MAX) {
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SLOGE("Service name '%s' is too long", name);
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return 0;
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}
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if (!isRunning(name)) {
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SLOGW("Service '%s' is already stopped", name);
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return 0;
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}
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SLOGD("Stopping service '%s'", name);
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property_set("ctl.stop", name);
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int count = SLEEP_MAX_USEC;
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while(count > 0) {
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usleep(SLEEP_MIN_USEC);
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count -= SLEEP_MIN_USEC;
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if (!isRunning(name))
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break;
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}
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if (count <= 0) {
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SLOGW("Timed out waiting for service '%s' to stop", name);
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errno = ETIMEDOUT;
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return -1;
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}
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SLOGD("Successfully stopped '%s'", name);
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return 0;
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}
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bool ServiceManager::isRunning(const char *name) {
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char propVal[PROPERTY_VALUE_MAX];
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char propName[PROPERTY_KEY_MAX];
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int ret;
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ret = snprintf(propName, sizeof(propName), "init.svc.%s", name);
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if (ret > (int)sizeof(propName)-1) {
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SLOGD("Service name '%s' is too long", name);
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return false;
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}
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if (property_get(propName, propVal, NULL)) {
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if (!strcmp(propVal, "running"))
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return true;
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}
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return false;
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}
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