Allow PromptHelper to be preempted

* e.g., if a host disconnects during password authentication, it immediately closes the password prompt

3 files changed, 110 insertions, 38 deletions

diff --git a/src/org/connectbot/ConsoleActivity.java b/src/org/connectbot/ConsoleActivity.java
index 4485f5b..00b1543 100644
--- a/src/org/connectbot/ConsoleActivity.java
+++ b/src/org/connectbot/ConsoleActivity.java
@@ -780,9 +780,12 @@ public class ConsoleActivity extends Activity {
 	protected void updatePromptVisible() {
 		// check if our currently-visible terminalbridge is requesting any prompt services
 		View view = findCurrentView(R.id.console_flip);
+
+		// Hide all the prompts in case a prompt request was canceled
+		hideAllPrompts();
+
 		if(!(view instanceof TerminalView)) {
 			// we dont have an active view, so hide any prompts
-			hideAllPrompts();
 			return;
 		}
 		
diff --git a/src/org/connectbot/service/PromptHelper.java b/src/org/connectbot/service/PromptHelper.java
index 9b783bb..2fc5183 100644
--- a/src/org/connectbot/service/PromptHelper.java
+++ b/src/org/connectbot/service/PromptHelper.java
@@ -12,44 +12,51 @@ import android.os.Message;
  * @author jsharkey
  */
 public class PromptHelper {
-	
 	private final Object tag;
+
+	private Handler handler = null;
+	
+	private Semaphore promptToken;
+	private Semaphore promptResponse;
+	
+	public String promptHint = null;
+	public Object promptRequested = null;
+	
+	private Object response = null;
 	
 	public PromptHelper(Object tag) {
 		this.tag = tag;
+		
+		// Threads must acquire this before they can send a prompt.
+		promptToken = new Semaphore(1);
+		
+		// Responses will release this semaphore.
+		promptResponse = new Semaphore(0);
 	}
 	
-	private Handler handler = null;
 
 	/**
 	 * Register a user interface handler, if available.
 	 */
-	public synchronized void setHandler(Handler handler) {
+	public void setHandler(Handler handler) {
 		this.handler = handler;
 	}
-	
-	private Semaphore promptResponse = new Semaphore(0);
-	
-	public String promptHint = null;
-	public Object promptRequested = null;
-	
-	private Object response = null;
 
 	/**
 	 * Set an incoming value from an above user interface. Will automatically
 	 * notify any waiting requests.
 	 */
 	public void setResponse(Object value) {
-		this.response = value;
-		this.promptResponse.release();
+		response = value;
+		promptResponse.release();
 	}
 	
 	/**
 	 * Return the internal response value just before erasing and returning it.
 	 */
 	protected Object popResponse() {
-		Object value = this.response;
-		this.response = null;
+		Object value = response;
+		response = null;
 		return value;
 	}
 
@@ -57,44 +64,98 @@ public class PromptHelper {
 	/**
 	 * Request a prompt response from parent. This is a blocking call until user
 	 * interface returns a value.
+	 * Only one thread can call this at a time. cancelPrompt() will force this to
+	 * immediately return.
 	 */
-	public synchronized Object requestPrompt(String hint, Object type) throws Exception {
-		this.promptHint = hint;
-		this.promptRequested = type;
+	private Object requestPrompt(String hint, Object type, boolean immediate) throws InterruptedException {
+		Object response = null;
+		
+		if (immediate)
+			cancelPrompt();
+		
+		promptToken.acquire();
+
+		try {
+			promptHint = hint;
+			promptRequested = type;
+			
+			// notify any parent watching for live events
+			if (handler != null)
+				Message.obtain(handler, -1, tag).sendToTarget();
 		
-		// notify any parent watching for live events
-		if(handler != null)
-			Message.obtain(handler, -1, tag).sendToTarget();
+			// acquire lock until user passes back value
+			promptResponse.acquire();
+			promptRequested = null;
+			
+			response = popResponse();
+		} finally {
+			promptToken.release();
+		}
 		
-		// acquire lock until user passes back value
-		this.promptResponse.acquire();
-		this.promptRequested = null;
-		return this.popResponse();
+		return response;
 	}
 	
 	/**
 	 * Request a string response from parent. This is a blocking call until user
 	 * interface returns a value.
+	 * @param hint prompt hint for user to answer
+	 * @param immediate whether to cancel other in-progress prompts
+	 * @return string user has entered
 	 */
-	public String requestStringPrompt(String hint) {
+	public String requestStringPrompt(String hint, boolean immediate) {
 		String value = null;
 		try {
-			value = (String)this.requestPrompt(hint, String.class);
+			value = (String)this.requestPrompt(hint, String.class, immediate);
 		} catch(Exception e) {
 		}
 		return value;
 	}
 	
 	/**
+	 * Convenience method for requestStringPrompt(String, boolean)
+	 * @param hint prompt hint for user to answer
+	 * @return string user has entered
+	 */
+	public String requestStringPrompt(String hint) {
+		return requestStringPrompt(hint, false);
+	}
+	
+	/**
 	 * Request a boolean response from parent. This is a blocking call until user
 	 * interface returns a value.
+	 * @param hint prompt hint for user to answer
+	 * @param immediate whether to cancel other in-progress prompts
+	 * @return choice user has made (yes/no)
 	 */
-	public Boolean requestBooleanPrompt(String hint) {
+	public Boolean requestBooleanPrompt(String hint, boolean immediate) {
 		Boolean value = null;
 		try {
-			value = (Boolean)this.requestPrompt(hint, Boolean.class);
+			value = (Boolean)this.requestPrompt(hint, Boolean.class, immediate);
 		} catch(Exception e) {
 		}
 		return value;
 	}
+	
+	/**
+	 * Convenience method for requestBooleanPrompt(String, boolean)
+	 * @param hint String to present to user in prompt
+	 * @return choice user has made (yes/no)
+	 */
+	public Boolean requestBooleanPrompt(String hint) {
+		return requestBooleanPrompt(hint, false);
+	}
+	
+	/**
+	 * Cancel an in-progress prompt.
+	 */
+	public void cancelPrompt() {
+		if (!promptToken.tryAcquire()) {
+			// A thread has the token, so try to interrupt it
+			response = null;
+			promptResponse.release();
+		} else {
+			// No threads have acquired the token
+			promptToken.release();
+		}
+	}
 }
diff --git a/src/org/connectbot/service/TerminalBridge.java b/src/org/connectbot/service/TerminalBridge.java
index 8ffd729..8024c88 100644
--- a/src/org/connectbot/service/TerminalBridge.java
+++ b/src/org/connectbot/service/TerminalBridge.java
@@ -368,9 +368,14 @@ public class TerminalBridge implements VDUDisplay, OnKeyListener, InteractiveCal
 		} else {
 			// otherwise load key from database and prompt for password as needed
 			String password = null;
-			if (pubkey.isEncrypted())
+			if (pubkey.isEncrypted()) {
 				password = promptHelper.requestStringPrompt(String.format("Password for key '%s'", pubkey.getNickname()));
-
+				
+				// Something must have interrupted the prompt.
+				if (password == null)
+					return false;
+			}
+			
 			if(PubkeyDatabase.KEY_TYPE_IMPORTED.equals(pubkey.getType())) {
 				// load specific key using pem format
 				trileadKey = PEMDecoder.decode(new String(pubkey.getPrivateKey()).toCharArray(), password);				
@@ -447,21 +452,24 @@ public class TerminalBridge implements VDUDisplay, OnKeyListener, InteractiveCal
 							break;
 						}
 					}
-					
 				} else {
-					outputLine("Attempting 'publickey' authentication with a specific SSH key");
+					outputLine("Attempting 'publickey' authentication with a specific public key");
 					// use a specific key for this host, as requested
 					PubkeyBean pubkey = manager.pubkeydb.findPubkeyById(pubkeyId);
-					if (tryPublicKey(pubkey))
-						finishConnection();
 					
+					if (pubkey == null)
+						outputLine("Selected public key is invalid, try reselecting key in host editor");
+					else
+						if (tryPublicKey(pubkey))
+							finishConnection();
 				}
 				
 				pubkeysExhausted = true;
 			} else if (connection.isAuthMethodAvailable(host.getUsername(), AUTH_PASSWORD)) {
 				outputLine("Attempting 'password' authentication");
 				String password = promptHelper.requestStringPrompt("Password");
-				if(connection.authenticateWithPassword(host.getUsername(), password)) {
+				if (password != null
+						&& connection.authenticateWithPassword(host.getUsername(), password)) {
 					finishConnection();
 				} else {
 					outputLine("Authentication method 'password' failed");
@@ -759,8 +767,8 @@ public class TerminalBridge implements VDUDisplay, OnKeyListener, InteractiveCal
 		} else {
 			new Thread(new Runnable() {
 				public void run() {
-					boolean result = promptHelper.requestBooleanPrompt("Host has disconnected.\nClose session?");
-					if (result) {
+					Boolean result = promptHelper.requestBooleanPrompt("Host has disconnected.\nClose session?", true);
+					if (result == null || result.booleanValue()) {
 						awaitingClose = true;
 						
 						// Tell the TerminalManager that we can be destroyed now.