harden attach sponsor process (#14)

- Improvement: Delay exiting due to no sponsor processes by one second to handle race conditions
- Improvement: Safer IsProcessRunning check
- Improvement: make sure we can RequestApplicationExit safely from any thread

3 files changed, 26 insertions, 11 deletions

diff --git a/src/zencore/include/zencore/zencore.h b/src/zencore/include/zencore/zencore.h
index e8c734ba9..1a9060e29 100644
--- a/src/zencore/include/zencore/zencore.h
+++ b/src/zencore/include/zencore/zencore.h
@@ -84,7 +84,7 @@ protected:
 namespace zen {
 
 ZENCORE_API bool IsApplicationExitRequested();
-ZENCORE_API void RequestApplicationExit(int ExitCode);
+ZENCORE_API bool RequestApplicationExit(int ExitCode);
 ZENCORE_API int	 ApplicationExitCode();
 ZENCORE_API bool IsDebuggerPresent();
 ZENCORE_API void SetIsInteractiveSession(bool Value);
diff --git a/src/zencore/process.cpp b/src/zencore/process.cpp
index e0a395494..d8be0d343 100644
--- a/src/zencore/process.cpp
+++ b/src/zencore/process.cpp
@@ -661,14 +661,13 @@ IsProcessRunning(int pid)
 	if (!hProc)
 	{
 		DWORD Error = zen::GetLastError();
-
 		if (Error == ERROR_INVALID_PARAMETER)
 		{
 			return false;
 		}
-
 		ThrowSystemError(Error, fmt::format("failed to open process with pid {}", pid));
 	}
+	auto _ = MakeGuard([hProc]() { CloseHandle(hProc); });
 
 	bool  bStillActive = true;
 	DWORD ExitCode	   = 0;
@@ -678,14 +677,25 @@ IsProcessRunning(int pid)
 	}
 	else
 	{
-		ZEN_WARN("Unable to get exit code from handle for process '{}', treating the process as active", pid);
+		DWORD Error = GetLastError();
+		ThrowSystemError(Error, fmt::format("failed to get process exit code for pid {}", pid));
 	}
-
-	CloseHandle(hProc);
-
 	return bStillActive;
 #elif ZEN_PLATFORM_LINUX || ZEN_PLATFORM_MAC
-	return (kill(pid_t(pid), 0) == 0);
+	int Res		  = kill(pid_t(pid), 0);
+	if (Res == 0)
+	{
+		return true;
+	}
+	int Error = errno;
+	if (Error == ESRCH)	 // No such process
+	{
+		return false;
+	}
+	else
+	{
+		ThrowSystemError(Error, fmt::format("Failed to signal running process %d: %d", pid, Error));
+	}
 #endif
 }
 
diff --git a/src/zencore/zencore.cpp b/src/zencore/zencore.cpp
index d0acac608..b80b1d280 100644
--- a/src/zencore/zencore.cpp
+++ b/src/zencore/zencore.cpp
@@ -115,11 +115,16 @@ IsApplicationExitRequested()
 	return s_ApplicationExitRequested;
 }
 
-void
+bool
 RequestApplicationExit(int ExitCode)
 {
-	s_ApplicationExitCode	   = ExitCode;
-	s_ApplicationExitRequested = true;
+	bool Expected = false;
+	if (s_ApplicationExitRequested.compare_exchange_weak(Expected, true))
+	{
+		s_ApplicationExitCode = ExitCode;
+		return true;
+	}
+	return false;
 }
 
 int