Handle process inspection race during shutdown

src/Shared/ProcessSignaler.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using Microsoft.Extensions.Logging;
@@ -49,32 +50,55 @@ public static void ForceKill(int pid, DateTimeOffset? expectedStartTime, ILogger
 
     public static Process? TryGetRunningProcess(int pid, DateTimeOffset? expectedStartTime, ILogger logger)
     {
+        Process? process = null;
         try
         {
-            var process = Process.GetProcessById(pid);
-            if (expectedStartTime is not null && !AreClose(expectedStartTime, process.StartTime))
+            process = Process.GetProcessById(pid);
+            if (process.HasExited)
             {
-                logger.LogDebug("Process {Pid} start time {ProcessStartTime} does not match expected start time {ExpectedStartTime}", pid, process.StartTime, expectedStartTime);
                 process.Dispose();
-                return null; // Do not return processes that do not match the expected start time
+                return null;
             }
 
-            if (process.HasExited)
+            if (expectedStartTime is not null)
             {
-                process.Dispose();
-                return null;
+                var processStartTime = process.StartTime;
+                if (!AreClose(expectedStartTime, processStartTime))
+                {
+                    logger.LogDebug("Process {Pid} start time {ProcessStartTime} does not match expected start time {ExpectedStartTime}", pid, processStartTime, expectedStartTime);
+                    process.Dispose();
+                    return null; // Do not return processes that do not match the expected start time
+                }
+
+                if (process.HasExited)
+                {
+                    process.Dispose();
+                    return null;
+                }
             }
 
             return process;
         }
         catch (ArgumentException)
         {
             // Process doesn't exist - already terminated.
+            process?.Dispose();
             return null;
         }
         catch (InvalidOperationException)
         {
             // Process has already exited.
+            process?.Dispose();
+            return null;
+        }
+        catch (Win32Exception ex)
+        {
+            // Process inspection can race with process exit. On macOS, StartTime can throw:
+            //   Win32Exception (3): Unable to retrieve the specified information about the process or thread. It may have exited or may be privileged.
+            // If we cannot inspect the process enough to prove it is the expected target, do
+            // not signal or kill it.
+            logger.LogDebug(ex, "Could not inspect process {Pid}. Treating it as not running.", pid);
+            process?.Dispose();
             return null;
         }
     }