Ignore calls from non-existent threads

The thread might have died after sending the message, so
it might not exist by the time the server gets the message.
In that case, just ignore/drop the message.

internal-include/darlingserver/registry.hpp

@@ -61,8 +61,14 @@ namespace DarlingServer {
 			_registeringWithLockHeld = true;
 			auto entry = entryFactory();
 			_registeringWithLockHeld = false;
+
+			if (!entry) {
+				return nullptr;
+			}
+
 			_map[entry->id()] = entry;
 			_nsmap[entry->nsid()] = entry;
+
 			return entry;
 		};
 

src/call.cpp

@@ -57,17 +57,48 @@ std::shared_ptr<DarlingServer::Call> DarlingServer::Call::callFromMessage(Messag
 	if ((header->number & DSERVER_CALL_UNMANAGED_FLAG) == 0) {
 		// now let's lookup (and possibly create) the process and thread making this call
 		process = processRegistry().registerIfAbsent(header->pid, [&]() {
-			auto tmp = std::make_shared<Process>(requestMessage.pid(), header->pid, static_cast<Process::Architecture>(header->architecture));
+			std::shared_ptr<Process> tmp = nullptr;
+
+			try {
+				tmp = std::make_shared<Process>(requestMessage.pid(), header->pid, static_cast<Process::Architecture>(header->architecture));
+			} catch (std::system_error e) {
+				return tmp;
+			}
+
 			Server::sharedInstance().monitorProcess(tmp);
 			return tmp;
 		});
+
+		if (!process) {
+			callLog.error() << "Received call from non-existent process?" << callLog.endLog;
+
+			// ignore this call
+			// TODO: instead of ignoring it, we should return a generic reply indicating `-ESRCH` or something like that.
+			return nullptr;
+		}
+
 		thread = threadRegistry().registerIfAbsent(header->tid, [&]() {
-			auto tmp = std::make_shared<Thread>(process, header->tid);
+			std::shared_ptr<Thread> tmp = nullptr;
+
+			try {
+				tmp = std::make_shared<Thread>(process, header->tid);
+			} catch (std::system_error e) {
+				return tmp;
+			}
+
 			tmp->setAddress(requestMessage.address());
 			tmp->registerWithProcess();
 			return tmp;
 		});
 
+		if (!thread) {
+			callLog.error() << "Received call from non-existent thread?" << callLog.endLog;
+
+			// ignore this call
+			// TODO: instead of ignoring it, we should return a generic reply indicating `-ESRCH` or something like that.
+			return nullptr;
+		}
+
 		thread->setAddress(requestMessage.address());
 
 		if (process->id() != requestMessage.pid()) {

src/thread.cpp

@@ -142,7 +142,7 @@ DarlingServer::Thread::Thread(std::shared_ptr<Process> process, NSID nsid):
 	}
 
 	if (_tid == -1) {
-		throw std::runtime_error("Failed to find thread ID within darlingserver's namespace");
+		throw std::system_error(ESRCH, std::generic_category(), "Failed to find thread ID within darlingserver's namespace");
 	}
 
 	_stackSize = THREAD_STACK_SIZE;