Fix kdesktop lock process hang / denial of servicekdesktop_lock_hang_fix

Under specific circumstances, kdesktop_lock may fail to engage the screen
lock when requested.  When this occurs, the user is typically present to
observe and attempt relock, however the kdesktop_lock process may not respond
once the lock has failed to engage and the process has not been restarted.

Add a fallback handler for SIGHUP (lock engage) to the kdesktop_lock startup
application thread.  This ensures the process will always respond to a lock
request regardless of lock process state.

Signed-off-by: Timothy Pearson <kb9vqf@pearsoncomputing.net>

3 files changed, 37 insertions, 3 deletions

diff --git a/kdesktop/lock/lockprocess.cpp b/kdesktop/lock/lockprocess.cpp
index 0a343d88e..234327001 100644
--- a/kdesktop/lock/lockprocess.cpp
+++ b/kdesktop/lock/lockprocess.cpp
@@ -4,7 +4,7 @@
 //
 // Copyright (c) 1999 Martin R. Jones <mjones@kde.org>
 // Copyright (c) 2003 Oswald Buddenhagen <ossi@kde.org>
-// Copyright (c) 2010 - 2015 Timothy Pearson <kb9vqf@pearsoncomputing.net>
+// Copyright (c) 2010 - 2024 Timothy Pearson <kb9vqf@pearsoncomputing.net>
 //
 
 //kdesktop keeps running and checks user inactivity
@@ -193,6 +193,9 @@ mHackDelayStartupTimer->stop();
 //
 LockProcess::LockProcess()
 	: TQWidget(0L, "saver window", ((WFlags)(WStyle_StaysOnTop|WStyle_Customize|WStyle_NoBorder))),
+	mInitialized(FALSE),
+	mLockPending(FALSE),
+	mLocked(FALSE),
 	mOpenGLVisual(0),
 	mParent(0),
 	mShowLockDateTime(false),
@@ -438,6 +441,8 @@ void LockProcess::init(bool child, bool useBlankOnly)
 	TQObject::connect(mControlPipeHandler, TQ_SIGNAL(processCommand(TQString)), this, TQ_SLOT(processInputPipeCommand(TQString)));
 	TQTimer::singleShot(0, mControlPipeHandler, TQ_SLOT(run()));
 	mControlPipeHandlerThread->start();
+
+	mInitialized = TRUE;
 }
 
 static int signal_pipe[2];
@@ -1477,6 +1482,13 @@ i18n("<i>kcheckpass</i> is unable to operate. Possibly it is not SetUID root.");
 //
 bool LockProcess::startLock()
 {
+	mLockPending = TRUE;
+
+	if (!mInitialized) {
+		// Don't hang if we're not even initialized yet -- startLock() was triggered prematurely
+		return false;
+	}
+
 	for (TQStringList::ConstIterator it = mPlugins.begin(); it != mPlugins.end(); ++it) {
 		GreeterPluginHandle plugin;
 		TQString path = KLibLoader::self()->findLibrary( ((*it)[0] == '/' ? *it : "kgreet_" + *it ).latin1() );
@@ -1507,6 +1519,7 @@ bool LockProcess::startLock()
 		kdDebug(KDESKTOP_DEBUG_ID) << "GreeterPlugin " << *it << " (" << plugin.info->method << ", " << plugin.info->name << ") loaded" << endl;
 		greetPlugin = plugin;
 		mLocked = true;
+		mLockPending = FALSE;
 		DM().setLock( true );
 		return true;
 	}
@@ -1973,6 +1986,11 @@ static void fakeFocusIn( WId window )
 	XSendEvent( tqt_xdisplay(), window, False, NoEventMask, &ev );
 }
 
+bool LockProcess::lockPending()
+{
+	return mLockPending;
+}
+
 void LockProcess::resumeUnforced()
 {
 	resume( false );
diff --git a/kdesktop/lock/lockprocess.h b/kdesktop/lock/lockprocess.h
index bfe1fe420..e2a761963 100644
--- a/kdesktop/lock/lockprocess.h
+++ b/kdesktop/lock/lockprocess.h
@@ -4,7 +4,7 @@
 //
 // Copyright (c) 1999 Martin R. Jones <mjones@kde.org>
 // Copyright (c) 2003 Oswald Buddenhagen <ossi@kde.org>
-// Copyright (c) 2010 - 2015 Timothy Pearson <kb9vqf@pearsoncomputing.net>
+// Copyright (c) 2010 - 2024 Timothy Pearson <kb9vqf@pearsoncomputing.net>
 //
 
 #ifndef __LOCKENG_H__
@@ -104,6 +104,8 @@ class LockProcess : public TQWidget
 		void msgBox( TQMessageBox::Icon type, const TQString &txt );
 		int execDialog( TQDialog* dlg );
 
+		bool lockPending();
+
 		TDECryptographicCardDevice* cryptographicCardDevice();
 
 	signals:
@@ -181,6 +183,8 @@ class LockProcess : public TQWidget
 		void generateBackingImages();
 		void fullyOnline();
 
+		bool        mInitialized;
+		bool        mLockPending;
 		bool        mLocked;
 		int         mLockGrace;
 		int         mPriority;
diff --git a/kdesktop/lock/main.cpp b/kdesktop/lock/main.cpp
index f80f406a1..1abb107ad 100644
--- a/kdesktop/lock/main.cpp
+++ b/kdesktop/lock/main.cpp
@@ -1,7 +1,7 @@
 /* This file is part of the TDE project
    Copyright (C) 1999 David Faure
    Copyright (c) 2003 Oswald Buddenhagen <ossi@kde.org>
-   Copyright (c) 2010-2015 Timothy Pearson <kb9vqf@pearsoncomputing.net>
+   Copyright (c) 2010-2024 Timothy Pearson <kb9vqf@pearsoncomputing.net>
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ -103,6 +103,12 @@ static void sigusr5_handler(int)
 	signalled_run = TRUE;
 }
 
+static void sighup_handler(int)
+{
+	signalled_forcelock = TRUE;
+	signalled_run = TRUE;
+}
+
 static int trapXErrors(Display *, XErrorEvent *)
 {
 	return 0;
@@ -428,6 +434,12 @@ int main( int argc, char **argv )
 			sigaddset(&(act.sa_mask), SIGTTOU);
 			act.sa_flags = 0;
 			sigaction(SIGTTOU, &act, 0L);
+			// handle SIGHUP (force lock, fallback handler)
+			act.sa_handler= sighup_handler;
+			sigemptyset(&(act.sa_mask));
+			sigaddset(&(act.sa_mask), SIGHUP);
+			act.sa_flags = 0;
+			sigaction(SIGHUP, &act, 0L);
 
 			// initialize the signal masks
 			sigemptyset(&new_mask);