launch_daemon: Check requirements before launching a job.

* They were only launched, but we didn't check if we can actually
  launch them.

src/servers/launch/Events.cpp

@@ -775,11 +775,13 @@ Events::ResetStickyExternalEvent(Event* event, const char* name)
 
 /*!	This will trigger a demand event, if it exists.
 
+	\param testOnly If \c true, the deman will not actually be triggered,
+			it will only be checked if it could.
 	\return \c true, if there is a demand event, and it has been
 			triggered by this call. \c false if not.
 */
 /*static*/ bool
-Events::TriggerDemand(Event* event)
+Events::TriggerDemand(Event* event, bool testOnly)
 {
 	if (event == NULL || event->Triggered())
 		return false;
@@ -789,11 +791,14 @@ Events::TriggerDemand(Event* event)
 				index++) {
 			Event* childEvent = container->Events().ItemAt(index);
 			if (dynamic_cast<DemandEvent*>(childEvent) != NULL) {
+				if (testOnly)
+					return true;
+
 				childEvent->Trigger();
 				break;
 			}
 			if (dynamic_cast<EventContainer*>(childEvent) != NULL) {
-				if (TriggerDemand(childEvent))
+				if (TriggerDemand(childEvent, testOnly))
 					break;
 			}
 		}

src/servers/launch/Events.h

@@ -62,7 +62,7 @@ public:
 								const char* name);
 	static	void			ResetStickyExternalEvent(Event* event,
 								const char* name);
-	static	bool			TriggerDemand(Event* event);
+	static	bool			TriggerDemand(Event* event, bool testOnly = false);
 };
 
 

src/servers/launch/LaunchDaemon.cpp

@@ -184,7 +184,11 @@ private:
 			void				_InitJobs(Target* target);
 			void				_LaunchJobs(Target* target,
 									bool forceNow = false);
-			void				_LaunchJob(Job* job, uint32 options = 0);
+			bool				_CanLaunchJob(Job* job, uint32 options,
+									bool testOnly = false);
+			bool				_CanLaunchJobRequirements(Job* job,
+									uint32 options);
+			bool				_LaunchJob(Job* job, uint32 options = 0);
 			void				_StopJob(Job* job, bool force);
 			void				_AddTarget(Target* target);
 			void				_SetCondition(BaseJob* job,
@@ -1428,6 +1432,45 @@ LaunchDaemon::_LaunchJobs(Target* target, bool forceNow)
 }
 
 
+/*!	Checks whether or not the specified \a job can be launched.
+	If \a testOnly is \c false, calling this method will trigger a demand
+	to the \a job.
+*/
+bool
+LaunchDaemon::_CanLaunchJob(Job* job, uint32 options, bool testOnly)
+{
+	if (job == NULL || !job->CanBeLaunched())
+		return false;
+
+	return (options & FORCE_NOW) != 0
+		|| (job->EventHasTriggered() && job->CheckCondition(*this)
+			&& ((options & TRIGGER_DEMAND) == 0
+				|| Events::TriggerDemand(job->Event(), testOnly)));
+}
+
+
+/*!	Checks recursively if the requirements of the specified job can be launched,
+	if they are not running already.
+	Calling this method will not trigger a demand for the requirements.
+*/
+bool
+LaunchDaemon::_CanLaunchJobRequirements(Job* job, uint32 options)
+{
+	int32 count = job->Requirements().CountStrings();
+	for (int32 index = 0; index < count; index++) {
+		Job* requirement = FindJob(job->Requirements().StringAt(index));
+		if (requirement != NULL
+			&& !requirement->IsRunning() && !requirement->IsLaunching()
+			&& (!_CanLaunchJob(requirement, options, true)
+				|| _CanLaunchJobRequirements(requirement, options))) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+
 /*!	Adds the specified \a job to the launch queue
 	queue, except those that are triggered by events.
 
@@ -1437,24 +1480,30 @@ LaunchDaemon::_LaunchJobs(Target* target, bool forceNow)
 	Calling this method will trigger a demand event if \c TRIGGER_DEMAND has
 	been set.
 */
-void
+bool
 LaunchDaemon::_LaunchJob(Job* job, uint32 options)
 {
-	if (job == NULL || !job->CanBeLaunched()
-		|| ((options & FORCE_NOW) == 0
-			&& (!job->EventHasTriggered() || !job->CheckCondition(*this)
-				|| ((options & TRIGGER_DEMAND) != 0
-						&& Events::TriggerDemand(job->Event()))))) {
-		return;
-	}
+	if (job != NULL && (job->IsLaunching() || job->IsRunning()))
+		return true;
 
+	if (!_CanLaunchJob(job, options))
+		return false;
+
+	// Test if we can launch all requirements
+	if (!_CanLaunchJobRequirements(job, options | TRIGGER_DEMAND))
+		return false;
+
+	// Actually launch the requirements
 	int32 count = job->Requirements().CountStrings();
 	for (int32 index = 0; index < count; index++) {
 		Job* requirement = FindJob(job->Requirements().StringAt(index));
 		if (requirement != NULL) {
 			// TODO: For jobs that have their communication channels set up,
 			// we would not need to trigger demand at this point
-			_LaunchJob(requirement, TRIGGER_DEMAND);
+			if (!_LaunchJob(requirement, options | TRIGGER_DEMAND)) {
+				// Failed to put a requirement into the launch queue
+				return false;
+			}
 		}
 	}
 
@@ -1469,7 +1518,10 @@ LaunchDaemon::_LaunchJob(Job* job, uint32 options)
 	if (status != B_OK) {
 		debug_printf("Adding job %s to queue failed: %s\n", job->Name(),
 			strerror(status));
+		return false;
 	}
+
+	return true;
 }