Fixes for many, but not all the things from zab's code review

java/net/i2p/router/WindowsUpdatePostProcessor.java

@@ -3,7 +3,10 @@ package net.i2p.router;
 import java.io.*;
 import java.util.*;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.*;
 
+
+import net.i2p.crypto.*;
 import static net.i2p.update.UpdateType.*;
 import net.i2p.I2PAppContext;
 import net.i2p.update.UpdateType;
@@ -18,36 +21,77 @@ import java.lang.InterruptedException;
 
 public class WindowsUpdatePostProcessor implements UpdatePostProcessor {
     private final Log _log = I2PAppContext.getGlobalContext().logManager().getLog(WindowsUpdatePostProcessor.class);
+    private final RouterContext ctx;
     protected static Router i2pRouter = null;
-
-    public void updateDownloadedandVerified(UpdateType type, int fileType, String version, File file) throws IOException {
-        if (fileType == 6) {
-            File newFile = moveUpdateInstaller(file);
-            runUpdateInstaller(newFile);
-        }
+    private final AtomicBoolean hook = new AtomicBoolean();
+    private volatile String version;
+    WindowsUpdatePostProcessor() {
+    	this.ctx = null;
     }
 
-    private File moveUpdateInstaller(File file){
+    WindowsUpdatePostProcessor(RouterContext ctx) {
+        this.ctx = ctx;
+    }
+
+    public String getVersion() {
+        return version;
+    }
+
+    public void updateDownloadedandVerified(UpdateType type, int fileType, String version, File file) throws IOException {
+        _log.info("Got an update to post-process");
+
+        if (type != UpdateType.ROUTER_SIGNED_SU3 && type != UpdateType.ROUTER_DEV_SU3) {
+            _log.warn("Unsupported update type " + type);
+            return;
+        }
+
+        if (fileType != SU3File.TYPE_EXE) {
+            _log.warn("Unsupported file type " + fileType);
+            return;
+        }
+
+        File positionedFile = moveUpdateInstaller(file);
+        
+        this.version = version;
+        
+        if (!hook.compareAndSet(false,true)) {
+            _log.info("shutdown hook was already set");
+            return;
+        }
+
+        _log.info("adding shutdown hook");
+        ctx.addFinalShutdownTask(new WinUpdateProcess(ctx, this::getVersion, positionedFile));
+
+    }
+    
+    private File moveUpdateInstaller(File file) throws IOException{
         RouterContext i2pContext = i2pRouter.getContext();
         if (i2pContext != null) {
             File appDir = i2pContext.getAppDir();
-            File newFile = new File(i2pContext.getAppDir().getAbsolutePath(), file.getName());
+            File newFile = new File(workDir(), file.getName());
             file.renameTo(newFile);
             return newFile;
         }
         return null;
     }
 
-    private void runUpdateInstaller(File file){
-        ProcessBuilder pb = new ProcessBuilder("cmd", "/c", file.getAbsolutePath(), "/S");
-        try {
-            pb.start();
-        } catch (IOException ex) {
-            if (_log.shouldWarn())
-                _log.warn("Unable to loop update-program in background. Update will fail.");
+    private File workDir() throws IOException{
+        RouterContext i2pContext = i2pRouter.getContext();
+        if (i2pContext != null) {
+            File workDir = new File(i2pContext.getAppDir().getAbsolutePath(), "i2p_update_win");
+            if (workDir.exists()) {
+                if (workDir.isFile())
+                    throw new IOException(workDir + " exists but is a file, get it out of the way");
+                    return null;
+            } else {
+                workDir.mkdirs();
+            }
+            return workDir;
         }
+        return null;
     }
 
+
     protected File selectProgramFile() {
         if (SystemVersion.isWindows()) {
             File jrehome = new File(System.getProperty("java.home"));