From 2696ea2322dfdd7b7a5b08843b6d8aca9aedd741 Mon Sep 17 00:00:00 2001
From: Dan Engelbrecht <dan.engelbrecht@epicgames.com>
Date: Wed, 8 Jan 2025 14:21:11 +0100
Subject: use attachconsole to send ctrl+c to running process

---
 src/zenutil/service.cpp | 83 ++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 42 deletions(-)

(limited to 'src/zenutil/service.cpp')

diff --git a/src/zenutil/service.cpp b/src/zenutil/service.cpp
index 44aa50494..3d7808bba 100644
--- a/src/zenutil/service.cpp
+++ b/src/zenutil/service.cpp
@@ -6,11 +6,6 @@
 #include <zencore/process.h>
 #include <zencore/scopeguard.h>
 #include <zencore/zencore.h>
-#include <zenutil/zenserverprocess.h>
-
-ZEN_THIRD_PARTY_INCLUDES_START
-#include <gsl/gsl-lite.hpp>
-ZEN_THIRD_PARTY_INCLUDES_END
 
 #if ZEN_PLATFORM_WINDOWS
 #	include <zencore/windows.h>
@@ -750,6 +745,46 @@ StartService(std::string_view ServiceName, ServiceLevel Level)
 	}
 }
 
+std::error_code
+SendSignalToProcess(DWORD dwProcessId, DWORD dwCtrlEvent)
+{
+	std::error_code Ec		  = {};
+	DWORD			ConsoleId = GetCurrentProcessId();
+	// Leave current console if it exists
+	// (otherwise AttachConsole will return ERROR_ACCESS_DENIED)
+	bool ConsoleDetached = FreeConsole() != FALSE;
+
+	if (AttachConsole(dwProcessId) != FALSE)
+	{
+		// Add a fake Ctrl-C handler for avoid instant kill is this console
+		// WARNING: do not revert it or current program will be also killed
+		SetConsoleCtrlHandler(nullptr, true);
+		if (GenerateConsoleCtrlEvent(dwCtrlEvent, 0) == FALSE)
+		{
+			Ec = MakeErrorCodeFromLastError();
+		}
+		FreeConsole();
+	}
+	else
+	{
+		Ec = MakeErrorCodeFromLastError();
+	}
+
+	if (ConsoleDetached)
+	{
+		// Create a new console if previous was deleted by OS
+		if (AttachConsole(ConsoleId) == FALSE)
+		{
+			int errorCode = GetLastError();
+			if (errorCode == 31)  // 31=ERROR_GEN_FAILURE
+			{
+				AllocConsole();
+			}
+		}
+	}
+	return Ec;
+}
+
 std::error_code
 StopRunService(bool AllUsers, std::string_view ServiceName)
 {
@@ -777,43 +812,7 @@ StopRunService(bool AllUsers, std::string_view ServiceName)
 				}
 				else
 				{
-					// This is hacky and checks if the running service is a zenserver instance and tries to shut down using the shutdown
-					// event
-					ExtendableStringBuilder<32> ChildShutdownEventName;
-					ZenServerState				State;
-					if (State.InitializeReadOnly())
-					{
-						State.Snapshot([&](const ZenServerState::ZenServerEntry& Entry) {
-							if (Entry.Pid == gsl::narrow<uint32_t>(Proc.Pid()))
-							{
-								ChildShutdownEventName << "Zen_" << Entry.EffectiveListenPort;
-								ChildShutdownEventName << "_Shutdown";
-							}
-						});
-						if (ChildShutdownEventName.Size() > 0)
-						{
-							NamedEvent Event(ChildShutdownEventName);
-							Ec = Event.Set();
-							if (Ec)
-							{
-								return Ec;
-							}
-							return {};
-						}
-					}
-					// This only works for a running process that does not already have a console attached - zenserver does have one
-					// hence the attempt to shut down using event above
-					if (AttachConsole(Proc.Pid()))
-					{
-						if (SetConsoleCtrlHandler(NULL, TRUE))
-						{
-							if (GenerateConsoleCtrlEvent(CTRL_C_EVENT, 0))
-							{
-								return {};
-							}
-						}
-					}
-					return MakeErrorCodeFromLastError();
+					return SendSignalToProcess(Proc.Pid(), CTRL_C_EVENT);
 				}
 			}
 			return MakeErrorCode(ERROR_INVALID_PARAMETER);
-- 
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