From 1b117ee64ae3ec6735fe95a998ef977cef9aa8ac Mon Sep 17 00:00:00 2001
From: Martin Ridgers <martin.ridgers@epicgames.com>
Date: Tue, 9 Nov 2021 16:53:26 +0100
Subject: Implemented ProcessHandle::Wait() for Linux

---
 zencore/thread.cpp | 35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

(limited to 'zencore/thread.cpp')

diff --git a/zencore/thread.cpp b/zencore/thread.cpp
index ba26fef36..a90d31a6c 100644
--- a/zencore/thread.cpp
+++ b/zencore/thread.cpp
@@ -15,6 +15,7 @@
 
 #	include <pthread.h>
 #	include <signal.h>
+#	include <time.h>
 #	include <unistd.h>
 #endif
 
@@ -411,6 +412,9 @@ ProcessHandle::Reset()
 bool
 ProcessHandle::Wait(int TimeoutMs)
 {
+	using namespace std::literals;
+
+#if ZEN_PLATFORM_WINDOWS
 	const DWORD Timeout = (TimeoutMs < 0) ? INFINITE : TimeoutMs;
 
 	const DWORD WaitResult = WaitForSingleObject(m_ProcessHandle, Timeout);
@@ -424,10 +428,35 @@ ProcessHandle::Wait(int TimeoutMs)
 			return false;
 
 		case WAIT_FAILED:
-			// What might go wrong here, and what is meaningful to act on?
-			using namespace std::literals;
-			ThrowLastError("Process::Wait failed"sv);
+			break;
 	}
+#elif ZEN_PLATFORM_LINUX
+	const int SleepMs = 20;
+	timespec SleepTime = { 0, SleepMs * 1000 * 1000 };
+	for (int i = 0; ; i += SleepMs)
+	{
+		if (i >= TimeoutMs)
+		{
+			return false;
+		}
+
+		if (kill(m_Pid, 0) < 0)
+		{
+			if (zen::GetLastError() == ESRCH)
+			{
+				return true;
+			}
+			break;
+		}
+
+		nanosleep(&SleepTime, nullptr);
+	}
+#else
+#	error Check kill() on this platform
+#endif
+
+	// What might go wrong here, and what is meaningful to act on?
+	ThrowLastError("Process::Wait failed"sv);
 
 	return false;
 }
-- 
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