zen startup hardening (#49)

- Feature: `zen up` command improvements
	- --`port` allows you to specify a base port when starting an instance
	- --`base-dir` allows you to specify a base directory for the zenserver executable if it is not located next to the zen.exe executable
- Feature: `zen down`
	- --`port` allows you to specify a base port when shutting down an instance
	- --`base-dir` allows you to specify a base directory for the zenserver executable if it is not located next to the zen.exe executable
	- --`force` if regular shutdown fails it tries to find a running zenserver.exe process and terminate it
	- If it fails to attach to the running server it now waits for it to exit when setting the RequestExit shared memory flag
- Improvement: zenserver now checks the RequestExit flag in the shared memory and exist gracefully if it is set
- Improvement: When adding a sponsor process to a running zenserver instance, we wait for it to be picked up from the shared memory section to determine success/fail

3 files changed, 55 insertions, 6 deletions

diff --git a/src/zenserver/main.cpp b/src/zenserver/main.cpp
index 6b31dc82e..2d2b24bbb 100644
--- a/src/zenserver/main.cpp
+++ b/src/zenserver/main.cpp
@@ -103,21 +103,42 @@ ZenEntryPoint::Run()
 		ServerState.Initialize();
 		ServerState.Sweep();
 
-		ZenServerState::ZenServerEntry* Entry = ServerState.Lookup(m_ServerOptions.BasePort);
-
-		if (Entry)
+		uint32_t						AttachSponsorProcessRetriesLeft = 3;
+		ZenServerState::ZenServerEntry* Entry							= ServerState.Lookup(m_ServerOptions.BasePort);
+		while (Entry)
 		{
 			if (m_ServerOptions.OwnerPid)
 			{
+				if (!IsProcessRunning(m_ServerOptions.OwnerPid))
+				{
+					ZEN_WARN("Sponsor owner pid {} is no longer running, will not add sponsor to process listening to port {} (pid: {})",
+							 m_ServerOptions.OwnerPid,
+							 m_ServerOptions.BasePort,
+							 Entry->Pid.load());
+					std::exit(1);
+				}
 				ZEN_INFO(
 					"Looks like there is already a process listening to this port {} (pid: {}), attaching owner pid {} to running instance",
 					m_ServerOptions.BasePort,
 					Entry->Pid.load(),
 					m_ServerOptions.OwnerPid);
 
-				Entry->AddSponsorProcess(m_ServerOptions.OwnerPid);
-
-				std::exit(0);
+				if (Entry->AddSponsorProcess(m_ServerOptions.OwnerPid))
+				{
+					std::exit(0);
+				}
+				if (AttachSponsorProcessRetriesLeft-- > 0)
+				{
+					Entry = ServerState.Lookup(m_ServerOptions.BasePort);
+				}
+				else
+				{
+					ZEN_WARN("Failed to add sponsor owner pid {} to process listening to port {} (pid: {})",
+							 m_ServerOptions.OwnerPid,
+							 m_ServerOptions.BasePort,
+							 Entry->Pid.load());
+					std::exit(1);
+				}
 			}
 			else
 			{
@@ -329,6 +350,11 @@ main(int argc, char* argv[])
 		}
 	}
 
+#if ZEN_PLATFORM_LINUX | ZEN_PLATFORM_MAC
+	// Detach ourselves from any parent process
+	setsid();
+#endif
+
 	signal(SIGINT, utils::SignalCallbackHandler);
 	signal(SIGTERM, utils::SignalCallbackHandler);
 
diff --git a/src/zenserver/zenserver.cpp b/src/zenserver/zenserver.cpp
index e6e451952..86dbc9617 100644
--- a/src/zenserver/zenserver.cpp
+++ b/src/zenserver/zenserver.cpp
@@ -475,6 +475,8 @@ ZenServer::InitializeState(const ZenServerOptions& ServerOptions)
 
 		EnqueueStateMarkerTimer();
 	}
+
+	EnqueueStateExitFlagTimer();
 }
 
 void
@@ -805,6 +807,14 @@ ZenServer::EnqueueSigIntTimer()
 }
 
 void
+ZenServer::EnqueueStateExitFlagTimer()
+{
+	m_SigIntTimer.expires_after(std::chrono::milliseconds(500));
+	m_SigIntTimer.async_wait([this](const asio::error_code&) { CheckStateExitFlag(); });
+	EnsureIoRunner();
+}
+
+void
 ZenServer::EnqueueStatsReportingTimer()
 {
 	m_StatsReportingTimer.expires_after(std::chrono::milliseconds(500));
@@ -858,6 +868,17 @@ ZenServer::CheckSigInt()
 	EnqueueSigIntTimer();
 }
 
+void
+ZenServer::CheckStateExitFlag()
+{
+	if (m_ServerEntry && m_ServerEntry->IsShutdownRequested())
+	{
+		RequestExit(0);
+		return;
+	}
+	EnqueueStateExitFlagTimer();
+}
+
 bool
 ZenServer::UpdateProcessMonitor()
 {
diff --git a/src/zenserver/zenserver.h b/src/zenserver/zenserver.h
index dd259f855..550047a5d 100644
--- a/src/zenserver/zenserver.h
+++ b/src/zenserver/zenserver.h
@@ -74,9 +74,11 @@ public:
 	void EnqueueProcessMonitorTimer();
 	void EnqueueStateMarkerTimer();
 	void EnqueueSigIntTimer();
+	void EnqueueStateExitFlagTimer();
 	void EnqueueStatsReportingTimer();
 	void CheckStateMarker();
 	void CheckSigInt();
+	void CheckStateExitFlag();
 	void CheckOwnerPid();
 	bool UpdateProcessMonitor();
 	void ScrubStorage();