diff --git a/clientscr/Mac_Saver_Module.h b/clientscr/Mac_Saver_Module.h
index 7b8c27ce63..6f13876d67 100644
--- a/clientscr/Mac_Saver_Module.h
+++ b/clientscr/Mac_Saver_Module.h
@@ -1,6 +1,6 @@
 // This file is part of BOINC.
 // http://boinc.berkeley.edu
-// Copyright (C) 2023 University of California
+// Copyright (C) 2024 University of California
 //
 // BOINC is free software; you can redistribute it and/or modify it
 // under the terms of the GNU Lesser General Public License
@@ -47,14 +47,15 @@ bool            getShow_default_ss_first();
 double          getGFXDefaultPeriod();
 double          getGFXSciencePeriod();
 double          getGGFXChangePeriod();
-void            incompatibleGfxApp(char * appPath, pid_t pid, int slot);
+void            incompatibleGfxApp(char * appPath, char * wuName, pid_t pid, int slot);
 void            setShow_default_ss_first(bool value);
 void            setGFXDefaultPeriod(double value);
 void            setGFXSciencePeriod(double value);
 void            setGGFXChangePeriod(double value);
 double          getDTime();
 void            doBoinc_Sleep(double seconds);
-void            launchedGfxApp(char * appPath, pid_t thePID, int slot);
+void            launchedGfxApp(char * appPath, char * wuName, pid_t thePID, int slot);
+int             compareBOINCLibVersionTo(int toMajor, int toMinor);
 void            print_to_log_file(const char *format, ...);
 void            strip_cr(char *buf);
 void            PrintBacktrace(void);
@@ -63,7 +64,8 @@ extern bool     gIsMojave;
 extern bool     gIsCatalina;
 extern bool     gIsHighSierra;
 extern bool     gIsSonoma;
-extern bool     gCant_Use_Shared_Offscreen_Buffer;
+extern bool     gMach_bootstrap_unavailable_to_screensavers;
+extern mach_port_name_t commsPort;
 
 #ifdef __cplusplus
 }	// extern "C"
diff --git a/clientscr/Mac_Saver_ModuleView.h b/clientscr/Mac_Saver_ModuleView.h
index 08a2b64eb0..3b7dc2d96b 100644
--- a/clientscr/Mac_Saver_ModuleView.h
+++ b/clientscr/Mac_Saver_ModuleView.h
@@ -1,6 +1,6 @@
 // This file is part of BOINC.
 // http://boinc.berkeley.edu
-// Copyright (C) 2023 University of California
+// Copyright (C) 2024 University of California
 //
 // BOINC is free software; you can redistribute it and/or modify it
 // under the terms of the GNU Lesser General Public License
@@ -51,8 +51,9 @@
 
 @property (NS_NONATOMIC_IOSONLY, readonly) GLuint currentTextureName;
 - (void)init:(NSView*)saverView;
-- (void)portDied:(NSNotification *)notification;
 - (void)testConnection;
+- (void)portDied:(NSNotification *)notification;
+- (void)cleanUpOpenGL;
 
 @end
 
@@ -84,14 +85,15 @@ bool            getShow_default_ss_first();
 double          getGFXDefaultPeriod();
 double          getGFXSciencePeriod();
 double          getGGFXChangePeriod();
-void            incompatibleGfxApp(char * appPath, pid_t pid, int slot);
+void            incompatibleGfxApp(char * appPath, char * wuName, pid_t pid, int slot);
 void            setShow_default_ss_first(bool value);
 void            setGFXDefaultPeriod(double value);
 void            setGFXSciencePeriod(double value);
 void            setGGFXChangePeriod(double value);
 double          getDTime();
 void            doBoinc_Sleep(double seconds);
-void            launchedGfxApp(char * appPath, pid_t thePID, int slot);
+void            launchedGfxApp(char * appPath, char * wuName, pid_t thePID, int slot);
+int             compareBOINCLibVersionTo(int toMajor, int toMinor);
 void            print_to_log_file(const char *format, ...);
 void            strip_cr(char *buf);
 void            PrintBacktrace(void);
@@ -100,7 +102,9 @@ extern bool     gIsCatalina;
 extern bool     gIsHighSierra;
 extern bool     gIsMojave;
 extern bool     gIsSonoma;
-extern bool     gCant_Use_Shared_Offscreen_Buffer;
+extern bool     gMach_bootstrap_unavailable_to_screensavers;
+extern mach_port_name_t commsPort;
+
 
 #ifdef __cplusplus
 }    // extern "C"
diff --git a/clientscr/Mac_Saver_ModuleView.m b/clientscr/Mac_Saver_ModuleView.m
index a92c1c120e..848fec6077 100644
--- a/clientscr/Mac_Saver_ModuleView.m
+++ b/clientscr/Mac_Saver_ModuleView.m
@@ -1,6 +1,6 @@
 // This file is part of BOINC.
 // http://boinc.berkeley.edu
-// Copyright (C) 2023 University of California
+// Copyright (C) 2024 University of California
 //
 // BOINC is free software; you can redistribute it and/or modify it
 // under the terms of the GNU Lesser General Public License
@@ -150,6 +150,7 @@ static pid_t childPid;
 static int gfxAppWindowNum;
 static NSView *imageView;
 static char gfxAppPath[MAXPATHLEN];
+static char gfxWuName[MAXPATHLEN];
 static int taskSlot;
 static NSRunningApplication *childApp;
 static double gfxAppStartTime;
@@ -175,12 +176,16 @@ static bool myIsPreview;
 #define MAXWAITFORCONNECTIONCATALINA 12.0
 #define MAX_CGWINDOWLIST_TRIES 3
 
+#define MAJORBOINCGFXLIBNEEDEDFORSONOMA 8
+#define MINORBOINCGFXLIBNEEDEDFORSONOMA 1
+
 int signof(float x) {
     return (x > 0.0 ? 1 : -1);
 }
 
-void launchedGfxApp(char * appPath, pid_t thePID, int slot) {
+void launchedGfxApp(char * appPath, char * wuName, pid_t thePID, int slot) {
     strlcpy(gfxAppPath, appPath, sizeof(gfxAppPath));
+    strlcpy(gfxWuName, wuName, sizeof(gfxWuName));
     childPid = thePID;
     taskSlot = slot;
     gfxAppStartTime = getDTime();
@@ -188,16 +193,24 @@ void launchedGfxApp(char * appPath, pid_t thePID, int slot) {
     if (thePID == 0) {
         useCGWindowList = false;
         gfxAppStartTime = 0.0;
+        gfxWuName[0] = '\0';
+        if (mySharedGraphicsController) {
+            [ mySharedGraphicsController cleanUpOpenGL ];
+        }
         if (imageView) {
             // removeFromSuperview must be called from main thread
-            if (pthread_equal(mainThreadID, pthread_self())) {
+            if (NSThread.isMainThread) {
                 [imageView removeFromSuperview];   // Releases imageView
-                imageView = nil;
+            } else {
+                dispatch_sync(dispatch_get_main_queue(), ^{
+                    [imageView removeFromSuperview];   // Releases imageView
+                });
             }
+            imageView = nil;
         }
-    } else {
-        if (gCant_Use_Shared_Offscreen_Buffer) {
-            stopAllGFXApps();
+    } else {    // thePID != 0
+        if (childPid) {
+            childApp = [NSRunningApplication runningApplicationWithProcessIdentifier:childPid];
         }
     }
 }
@@ -408,7 +421,13 @@ void launchedGfxApp(char * appPath, pid_t thePID, int slot) {
     if (imageView) {
         useCGWindowList = false;
         // removeFromSuperview must be called from main thread
-        [imageView removeFromSuperview];   // Releases imageView
+        if (NSThread.isMainThread) {
+            [imageView removeFromSuperview];   // Releases imageView
+        } else {
+            dispatch_sync(dispatch_get_main_queue(), ^{
+                [imageView removeFromSuperview];   // Releases imageView
+            });
+        }
         imageView = nil;
     }
 
@@ -563,7 +582,7 @@ void launchedGfxApp(char * appPath, pid_t thePID, int slot) {
         //
         if (childApp) {
              if (![ childApp activateWithOptions:NSApplicationActivateIgnoringOtherApps ]) {
-                launchedGfxApp("", 0, -1);  // Graphics app is no longer running
+                launchedGfxApp("", "", 0, -1);  // Graphics app is no longer running
              } else if (useCGWindowList) {
                 // As a safety precaution, prevent terminating gfx app while copying its window
                 pthread_mutex_lock(&saver_mutex);
@@ -611,7 +630,13 @@ void launchedGfxApp(char * appPath, pid_t thePID, int slot) {
 
     if (imageView && !useCGWindowList) {
         // removeFromSuperview must be called from main thread
-        [imageView removeFromSuperview];   // Releases imageView
+        if (NSThread.isMainThread) {
+            [imageView removeFromSuperview];   // Releases imageView
+        } else {
+            dispatch_sync(dispatch_get_main_queue(), ^{
+                [imageView removeFromSuperview];   // Releases imageView
+            });
+        }
         imageView = nil;
     }
 
@@ -631,16 +656,26 @@ void launchedGfxApp(char * appPath, pid_t thePID, int slot) {
             maxWaitTime = gIsCatalina ? MAXWAITFORCONNECTIONCATALINA : MAXWAITFORCONNECTION;
             if ((getDTime() - gfxAppStartTime) > maxWaitTime) {
                 if (gIsCatalina) {
+                    if (gMach_bootstrap_unavailable_to_screensavers) {
+                        // Is the gfx app built with a new enough BOINC graphics library version?
+                        if (compareBOINCLibVersionTo(MAJORBOINCGFXLIBNEEDEDFORSONOMA, MINORBOINCGFXLIBNEEDEDFORSONOMA) >= 0) {
+                            runningSharedGraphics = true;
+                            if (childPid) {
+                                gfxAppStartTime = 0.0;
+                                childApp = [NSRunningApplication runningApplicationWithProcessIdentifier:childPid];
+                            }
+                        }
+                    }
                     // CGWindowListCopyWindowInfo and CGWindowListCreateImage can copy
                     // windows between user boinc_project and the user running the
                     // screensaver only if OS < 10.15 (before Catalina)
-                    incompatibleGfxApp(gfxAppPath, childPid, taskSlot);
+                    incompatibleGfxApp(gfxAppPath, gfxWuName, childPid, taskSlot);
                 } else {
                     if (++CGWindowListTries > MAX_CGWINDOWLIST_TRIES) {
                         // After displaying message for 5 seconds, incompatibleGfxApp
                         // will call launchedGfxApp("", 0, -1) which will clear
                         // gfxAppStartTime and CGWindowListTries
-                        incompatibleGfxApp(gfxAppPath, childPid, taskSlot);
+                        incompatibleGfxApp(gfxAppPath, gfxWuName, childPid, taskSlot);
                     } else {
                         if ([self setUpToUseCGWindowList]) {
                             CGWindowListTries = 0;
@@ -1088,12 +1123,14 @@ static bool okToDraw;
     [[NSNotificationCenter defaultCenter] removeObserver:self
         name:NSPortDidBecomeInvalidNotification object:nil];
 
-    [[NSNotificationCenter defaultCenter] addObserver:self
-        selector:@selector(portDied:) name:NSPortDidBecomeInvalidNotification object:nil];
-
     openGLView = nil;
 
     [self testConnection];
+
+    if (! gMach_bootstrap_unavailable_to_screensavers)  {
+        [[NSNotificationCenter defaultCenter] addObserver:self
+            selector:@selector(portDied:) name:NSPortDidBecomeInvalidNotification object:nil];
+    }
 }
 
 
@@ -1101,60 +1138,129 @@ static bool okToDraw;
 {
     mach_port_t servicePortNum = MACH_PORT_NULL;
     kern_return_t machErr;
-    char *portName = "edu.berkeley.boincsaver";
+    char *portNameV1 = "edu.berkeley.boincsaver";
+    char *portNameV2 = "edu.berkeley.boincsaver-v2";
 
-	// Try to check in with master.
+    if ((!gMach_bootstrap_unavailable_to_screensavers) || (serverPort == MACH_PORT_NULL)) {
+       // Try to check in with master.
 // NSMachBootstrapServer is deprecated in OS 10.13, so use bootstrap_look_up
 //	serverPort = [(NSMachPort *)([[NSMachBootstrapServer sharedInstance] portForName:@"edu.berkeley.boincsaver"]) retain];
-	machErr = bootstrap_look_up(bootstrap_port, portName, &servicePortNum);
-    if (machErr == KERN_SUCCESS) {
-        serverPort = (NSMachPort*)[NSMachPort portWithMachPort:servicePortNum];
-    } else {
-        if (machErr == BOOTSTRAP_NOT_PRIVILEGED) {
-            // As of MacOS 14.0, the legacyScreenSave sandbox prevents using
-            // IOSurfaceLookupFromMachPort. I have filed bug report FB13300491
-            // with Apple and hope they will change this in future MacOS.
-            gCant_Use_Shared_Offscreen_Buffer = true;
-            stopAllGFXApps();
+        machErr = bootstrap_look_up(bootstrap_port, portNameV1, &servicePortNum);
+        if (machErr != KERN_SUCCESS) {
+            if (machErr != BOOTSTRAP_NOT_PRIVILEGED) {
+            //  bootstrap_look_up() returned error other than BOOTSTRAP_NOT_PRIVILEGED
+            // machErr is probably BOOTSTRAP_UNKNOWN_SERVICE because no gfx app is running
+            // Keep trying bootstrap_look_up() until we get a connection from gfx app
+            serverPort = MACH_PORT_NULL;
+            } else {    //  bootstrap_look_up() returned error BOOTSTRAP_NOT_PRIVILEGED
+                // As of MacOS 14.0, the legacyScreenSave sandbox prevents using
+                // bootstrap_look_up. I have filed bug report FB13300491 with
+                // Apple and hope they will change this in a future MacOS.
+                machErr = bootstrap_check_in(bootstrap_port, portNameV2, &servicePortNum);
+                if (machErr != KERN_SUCCESS) {
+                    [NSApp terminate:nil];
+                }
+                gMach_bootstrap_unavailable_to_screensavers = true;
+            }   //  bootstrap_look_up() returned error BOOTSTRAP_NOT_PRIVILEGED
+        }   // bootstrap_look_up() did not return KERN_SUCCESS
+
+         if (machErr == KERN_SUCCESS) {
+           serverPort = (NSMachPort*)[NSMachPort portWithMachPort:servicePortNum];
+        }
+
+        if ((serverPort != MACH_PORT_NULL) && (localPort == MACH_PORT_NULL)) {
+            // Retrieve raw mach port names.
+            serverPortName = [serverPort machPort];
+
+            if (gMach_bootstrap_unavailable_to_screensavers) {
+               // Register server port with the current runloop.
+                [serverPort setDelegate:self];
+                [serverPort scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
+            } else {    // (! gMach_bootstrap_unavailable_to_screensavers)
+                // Create our own local port.
+                localPort = [[NSMachPort alloc] init];
+                localPortName  = [localPort machPort];
+                // Register our local port with the current runloop.
+                [localPort setDelegate:self];
+                [localPort scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
+
+                // Check in with server.
+                int kr;
+                kr = _MGCCheckinClient(serverPortName, localPortName, &clientIndex);
+                if(kr != 0) {
+                    [NSApp terminate:nil];
+                }
+
+                runningSharedGraphics = true;
+
+                if (childPid) {
+                    gfxAppStartTime = 0.0;
+                    childApp = [NSRunningApplication runningApplicationWithProcessIdentifier:childPid];
+                }
+            }   // (! gMach_bootstrap_unavailable_to_screensavers)
+        }   // ((serverPort != MACH_PORT_NULL) && (localPort == MACH_PORT_NULL))
+    }   // ((!gMach_bootstrap_unavailable_to_screensavers) || (serverPort == MACH_PORT_NULL))
+}
+
+
+- (void)cleanUpOpenGL
+{
+    if (gMach_bootstrap_unavailable_to_screensavers) {
+        [serverPort removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
+    }
+    childPid=0;
+    childApp = nil;
+
+    if (gMach_bootstrap_unavailable_to_screensavers ||
+            ((serverPort == MACH_PORT_NULL) && (localPort == MACH_PORT_NULL))
+            ) {
+        if (openGLView) {
+            if (NSThread.isMainThread) {
+                [openGLView removeFromSuperview];   // Releases openGLView
+            } else {
+                dispatch_sync(dispatch_get_main_queue(), ^{
+                    [openGLView removeFromSuperview];   // Releases openGLView
+                });
+            }
+            openGLView = nil;
+        }
+
+    int i;
+    for(i = 0; i < NUM_IOSURFACE_BUFFERS; i++) {
+        if (_ioSurfaceBuffers[i]) {
+            CFRelease(_ioSurfaceBuffers[i]);
+            _ioSurfaceBuffers[i] = nil;
+        }
+
+        // if (glIsTexture(_textureNames[i])) {
+            // glDeleteTextures(1, _textureNames[i]);
+        // }
+        _textureNames[i] = 0;
+
+        if (_ioSurfaceMachPorts[i] != MACH_PORT_NULL) {
+            mach_port_deallocate(mach_task_self(), _ioSurfaceMachPorts[i]);
+            _ioSurfaceMachPorts[i] = MACH_PORT_NULL;
         }
-        serverPort = MACH_PORT_NULL;
     }
 
-	if ((serverPort != MACH_PORT_NULL) && (localPort == MACH_PORT_NULL))
-	{
-		// Create our own local port.
-		localPort = [[NSMachPort alloc] init];
-
-		// Retrieve raw mach port names.
-		serverPortName = [serverPort machPort];
-		localPortName  = [localPort machPort];
-
-		// Register our local port with the current runloop.
-		[localPort setDelegate:self];
-		[localPort scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
-
-		// Check in with server.
-		int kr;
-		kr = _MGCCheckinClient(serverPortName, localPortName, &clientIndex);
-		if(kr != 0)
-			[NSApp terminate:nil];
-
-        runningSharedGraphics = true;
-
-        if (childPid) {
-            gfxAppStartTime = 0.0;
-            childApp = [NSRunningApplication runningApplicationWithProcessIdentifier:childPid];
+        runningSharedGraphics = false;  // Do this last!!
+        if (gMach_bootstrap_unavailable_to_screensavers) {
+            [serverPort scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
         }
     }
 }
 
 - (void)portDied:(NSNotification *)notification
 {
+    if (gMach_bootstrap_unavailable_to_screensavers) {
+        return; // This should never be called if using MacOS 14 workaround
+    }
 	NSPort *port = [notification object];
 	if(port == serverPort) {
         childApp = nil;
         gfxAppStartTime = 0.0;
         gfxAppPath[0] = '\0';
+        gfxWuName[0] = '\0';
 
         if ([serverPort isValid]) {
             [serverPort invalidate];
@@ -1169,29 +1275,7 @@ static bool okToDraw;
 //        [localPort release];
         localPort = MACH_PORT_NULL;
 
-        int i;
-        for(i = 0; i < NUM_IOSURFACE_BUFFERS; i++) {
-            if (_ioSurfaceBuffers[i]) {
-                CFRelease(_ioSurfaceBuffers[i]);
-                _ioSurfaceBuffers[i] = nil;
-            }
-
-            // if (glIsTexture(_textureNames[i])) {
-                // glDeleteTextures(1, _textureNames[i]);
-            // }
-            _textureNames[i] = 0;
-
-            if (_ioSurfaceMachPorts[i] != MACH_PORT_NULL) {
-                mach_port_deallocate(mach_task_self(), _ioSurfaceMachPorts[i]);
-                _ioSurfaceMachPorts[i] = MACH_PORT_NULL;
-            }
-        }
-
-        if ((serverPort == MACH_PORT_NULL) && (localPort == MACH_PORT_NULL)) {
-            runningSharedGraphics = false;
-            [openGLView removeFromSuperview];   // Releases openGLView
-            openGLView = nil;
-        }
+        [ self cleanUpOpenGL ];
 	}
 }
 
@@ -1206,13 +1290,16 @@ static bool okToDraw;
 	{
 		kr = mach_msg(reply_header, MACH_SEND_MSG, reply_header->msgh_size, 0, MACH_PORT_NULL,
 			     0, MACH_PORT_NULL);
-        if(kr != 0)
+        if(kr != 0) {
 			[NSApp terminate:nil];
+        }
 	}
 }
 
 - (kern_return_t)displayFrame:(int32_t)frameIndex surfacemachport:(mach_port_t)iosurface_port
 {
+    if (!childPid) return 0;
+
 	nextFrameIndex = frameIndex;
 
 	if(!_ioSurfaceBuffers[frameIndex])
@@ -1239,11 +1326,21 @@ static bool okToDraw;
 		_textureNames[frameIndex] = [openGLView setupIOSurfaceTexture:_ioSurfaceBuffers[frameIndex]];
     }
 
-    okToDraw = true;    // Tell drawRect that we have real data to display
+    if (openGLView) {
+        okToDraw = true;    // Tell drawRect that we have real data to display
 
-	[openGLView setNeedsDisplay:YES];
-	[openGLView display];
+        [openGLView setNeedsDisplay:YES];
+        [openGLView display];
+    }
 
+    if (gMach_bootstrap_unavailable_to_screensavers && (runningSharedGraphics == false)) {
+        // We have now heard from gfx app so connection has been established
+        runningSharedGraphics = true;
+        if (childPid) {
+            gfxAppStartTime = 0.0;
+            childApp = [NSRunningApplication runningApplicationWithProcessIdentifier:childPid];
+        }
+    }
 	return 0;
 }
 
@@ -1283,8 +1380,9 @@ kern_return_t _MGSDisplayFrame(mach_port_t server_port, int32_t frame_index, mac
 
     NSOpenGLPixelFormat *pix_fmt = [[NSOpenGLPixelFormat alloc] initWithAttributes:attribs];
 
-    if(!pix_fmt)
+    if(!pix_fmt) {
        [ NSApp terminate:nil];
+    }
 
 	self = [super initWithFrame:frame pixelFormat:pix_fmt];
 
@@ -1431,12 +1529,6 @@ static bool UseSharedOffscreenBuffer() {
     static bool needSharedGfxBuffer = false;
 
 //return true;    // FOR TESTING ONLY
-    // As of MacOS 14.0, the legacyScreenSaver sandbox prevents using
-    // IOSurfaceLookupFromMachPort. I have filed bug report FB13300491
-    // with Apple and hope they will change this in future MacOS.
-    if (gCant_Use_Shared_Offscreen_Buffer) {
-        return false;
-    }
     if (alreadyTested) {
         return needSharedGfxBuffer;
     }
diff --git a/clientscr/gfx_cleanup.mm b/clientscr/gfx_cleanup.mm
index 9ed6455961..214506e18f 100644
--- a/clientscr/gfx_cleanup.mm
+++ b/clientscr/gfx_cleanup.mm
@@ -1,6 +1,6 @@
 // This file is part of BOINC.
 // http://boinc.berkeley.edu
-// Copyright (C) 2023 University of California
+// Copyright (C) 2024 University of California
 //
 // BOINC is free software; you can redistribute it and/or modify it
 // under the terms of the GNU Lesser General Public License
@@ -51,9 +51,17 @@ int GFX_PidFromScreensaver = 0;
 pthread_t MonitorParentThread = 0;
 bool quit_MonitorParentThread = false;
 
+// struct ss_shmem_data must be kept in sync in these files:
+// screensaver.cpp
+// gfx_switcher.cpp
+// gfx_cleanup.mm
+// graphics2_unix.cpp
 struct ss_shmem_data {
     pid_t gfx_pid;
     int gfx_slot;
+    int major_version;
+    int minor_version;
+    int release;
 };
 
 static struct ss_shmem_data* ss_shmem = NULL;
@@ -122,6 +130,9 @@ void killGfxApp(pid_t thePID) {
     if (ss_shmem) {
         rpc->run_graphics_app("stop", ss_shmem->gfx_slot, "");
         ss_shmem->gfx_slot = -1;
+        ss_shmem->major_version = 0;
+        ss_shmem->minor_version = 0;
+        ss_shmem->release = 0;
     }
 
     rpc->close();
diff --git a/clientscr/gfx_switcher.cpp b/clientscr/gfx_switcher.cpp
index c0b4efdb73..1e18cc62e0 100644
--- a/clientscr/gfx_switcher.cpp
+++ b/clientscr/gfx_switcher.cpp
@@ -1,6 +1,6 @@
 // This file is part of BOINC.
 // http://boinc.berkeley.edu
-// Copyright (C) 2023 University of California
+// Copyright (C) 2024 University of California
 //
 // BOINC is free software; you can redistribute it and/or modify it
 // under the terms of the GNU Lesser General Public License
@@ -82,9 +82,17 @@ static void strip_cr(char *buf);
 
 void * MonitorScreenSaverEngine(void* param);
 
+// struct ss_shmem_data must be kept in sync in these files:
+// screensaver.cpp
+// gfx_switcher.cpp
+// gfx_cleanup.mm
+// graphics2_unix.cpp
 struct ss_shmem_data {
     pid_t gfx_pid;
     int gfx_slot;
+    int major_version;
+    int minor_version;
+    int release;
 };
 
 static struct ss_shmem_data* ss_shmem = NULL;
@@ -222,6 +230,9 @@ int main(int argc, char** argv) {
             pthread_cancel(monitorScreenSaverEngineThread);
             if (ss_shmem != 0) {
                 ss_shmem->gfx_pid = 0;
+                ss_shmem->major_version = 0;
+                ss_shmem->minor_version = 0;
+                ss_shmem->release = 0;
             }
             return 0;
         }
@@ -287,6 +298,9 @@ int main(int argc, char** argv) {
             pthread_cancel(monitorScreenSaverEngineThread);
             if (ss_shmem != 0) {
                 ss_shmem ->gfx_pid = 0;
+                ss_shmem->major_version = 0;
+                ss_shmem->minor_version = 0;
+                ss_shmem->release = 0;
             }
             return 0;
         }
diff --git a/clientscr/mac_saver_module.cpp b/clientscr/mac_saver_module.cpp
index 283effcd35..b67cc92ac3 100644
--- a/clientscr/mac_saver_module.cpp
+++ b/clientscr/mac_saver_module.cpp
@@ -1,6 +1,6 @@
 // This file is part of BOINC.
 // http://boinc.berkeley.edu
-// Copyright (C) 2023 University of California
+// Copyright (C) 2024 University of California
 //
 // BOINC is free software; you can redistribute it and/or modify it
 // under the terms of the GNU Lesser General Public License
@@ -112,8 +112,8 @@ bool gIsCatalina = false;   // OS 10.15 or later
 bool gIsSonoma = false;     // OS 14.0 or later
 
 // As of MacOS 14.0, the legacyScreenSave sandbox
-// prevents using IOSurfaceLookupFromMachPort.
-bool gCant_Use_Shared_Offscreen_Buffer = false;
+// prevents using bootstrap_look_up.
+bool gMach_bootstrap_unavailable_to_screensavers = false;
 
 const char *  CantLaunchCCMsg = "Unable to launch BOINC application.";
 const char *  LaunchingCCMsg = "Launching BOINC application.";
@@ -128,7 +128,6 @@ const char *  DefaultGFXAppCrashedMsg = "Default screensaver module had an unrec
 const char *  RunningOnBatteryMsg = "Computing and screensaver disabled while running on battery power.";
 const char *  IncompatibleMsg = "Could not connect to screensaver ";
 const char *  CCNotRunningMsg = "BOINC is not running.";
-const char *  NoScreenSaverGraphicsThisMacOS = "BOINC can't show screensaver graphics on this version of MacOS";
 
 //const char *  BOINCExitedSaverMode = "BOINC is no longer in screensaver mode.";
 
@@ -207,7 +206,7 @@ void closeBOINCSaver() {
 }
 
 
-void incompatibleGfxApp(char * appPath, pid_t pid, int slot){
+void incompatibleGfxApp(char * appPath, char * wuName, pid_t pid, int slot){
     char *p;
     static char buf[1024];
     static double msgstartTime = 0.0;
@@ -253,8 +252,8 @@ void incompatibleGfxApp(char * appPath, pid_t pid, int slot){
         }   // End if (msgstartTime == 0.0)
 
         if (msgstartTime && (getDTime() - msgstartTime > 5.0)) {
-            gspScreensaver->markAsIncompatible(appPath);
-            launchedGfxApp("", 0, -1);
+            gspScreensaver->markAsIncompatible(wuName);
+            launchedGfxApp("", "", 0, -1);
             msgstartTime = 0.0;
             gspScreensaver->terminate_v6_screensaver(pid);
         }
@@ -356,7 +355,6 @@ CScreensaver::CScreensaver() {
     GetDefaultDisplayPeriods(periods);
     m_bShow_default_ss_first = periods.Show_default_ss_first;
 
-
     m_fGFXDefaultPeriod = periods.GFXDefaultPeriod;
     m_fGFXSciencePeriod = periods.GFXSciencePeriod;
     m_fGFXChangePeriod = periods.GFXChangePeriod;
@@ -479,11 +477,6 @@ int CScreensaver::getSSMessage(char **theMessage, int* coveredFreq) {
         return NOTEXTLOGOFREQUENCY;
     }
 
-    if (gCant_Use_Shared_Offscreen_Buffer) {
-        gspScreensaver->setSSMessageText(NoScreenSaverGraphicsThisMacOS);
-        goto msgIsSet;
-    }
-
     CheckDualGPUPowerSource();
 
     switch (saverState) {
@@ -654,7 +647,6 @@ int CScreensaver::getSSMessage(char **theMessage, int* coveredFreq) {
         }
     }
 
-msgIsSet:
     if (m_MessageText[0]) {
         newFrequency = TEXTLOGOFREQUENCY;
     } else {
diff --git a/clientscr/screensaver.cpp b/clientscr/screensaver.cpp
index 6a5a750d44..c3ca1c7ed7 100644
--- a/clientscr/screensaver.cpp
+++ b/clientscr/screensaver.cpp
@@ -1,6 +1,6 @@
 // This file is part of BOINC.
 // http://boinc.berkeley.edu
-// Copyright (C) 2023 University of California
+// Copyright (C) 2024 University of California
 //
 // BOINC is free software; you can redistribute it and/or modify it
 // under the terms of the GNU Lesser General Public License
@@ -102,13 +102,23 @@ extern pthread_mutex_t saver_mutex;
 RESULT* graphics_app_result_ptr = NULL;
 
 #ifdef __APPLE__
+// struct ss_shmem_data must be kept in sync in these files:
+// screensaver.cpp
+// gfx_switcher.cpp
+// gfx_cleanup.mm
+// graphics2_unix.cpp
 struct ss_shmem_data {
     pid_t gfx_pid;
     int gfx_slot;
+    int major_version;
+    int minor_version;
+    int release;
 };
 
 static struct ss_shmem_data* ss_shmem = NULL;
 bool canAccessProjectGFXApps = true;
+static double graphicsAppStartTime;
+
 #endif
 
 bool CScreensaver::is_same_task(RESULT* taska, RESULT* taskb) {
@@ -136,10 +146,10 @@ int CScreensaver::count_active_graphic_apps(RESULTS& res, RESULT* exclude) {
         if (is_same_task(res.results[i], exclude)) continue;
 #ifdef __APPLE__
         // Remove it from the vector if incompatible with current version of OS X
-        if (isIncompatible(res.results[i]->graphics_exec_path)) {
+        if (isIncompatible(res.results[i]->wu_name)) {
             BOINCTRACE(
                 _T("count_active_graphic_apps -- removing incompatible name = '%s', path = '%s'\n"),
-                res.results[i]->name, res.results[i]->graphics_exec_path
+                res.results[i]->wu_name, res.results[i]->graphics_exec_path
             );
             RESULT *rp = res.results[i];
             res.results.erase(res.results.begin()+i);
@@ -211,23 +221,23 @@ CLEANUP:
 
 
 #ifdef __APPLE__
-void CScreensaver::markAsIncompatible(char *gfxAppPath) {
-    char *buf = (char *)malloc(strlen(gfxAppPath)+1);
+void CScreensaver::markAsIncompatible(char *wuName) {
+    char *buf = (char *)malloc(strlen(wuName)+1);
     if (buf) {
-        strlcpy(buf, gfxAppPath, malloc_size(buf));
+        strlcpy(buf, wuName, malloc_size(buf));
         m_vIncompatibleGfxApps.push_back(buf);
-       BOINCTRACE(_T("markAsIncompatible -- path = '%s'\n"), gfxAppPath);
+       BOINCTRACE(_T("markAsIncompatible -- wuName = '%s'\n"), wuName);
     }
 }
 
-bool CScreensaver::isIncompatible(char *appPath) {
+bool CScreensaver::isIncompatible(char *wuName) {
     unsigned int i = 0;
     for (i = 0; i < m_vIncompatibleGfxApps.size(); i++) {
         BOINCTRACE(
             _T("isIncompatible -- comparing incompatible path '%s' to candidate path %s\n"),
-            m_vIncompatibleGfxApps[i], appPath
+            m_vIncompatibleGfxApps[i], wuName
         );
-        if (strcmp(m_vIncompatibleGfxApps[i], appPath) == 0) {
+        if (strcmp(m_vIncompatibleGfxApps[i], wuName) == 0) {
             return true;
         }
     }
@@ -266,7 +276,7 @@ int CScreensaver::launch_screensaver(RESULT* rp, PROCESS_REF& graphics_applicati
         // V6 Graphics
 #ifdef __APPLE__
         graphics_application = 0;
-
+        graphicsAppStartTime = 0;
         // As of OS 10.15 (Catalina) screensavers can no longer:
         //  - launch apps that run setuid or setgid
         //  - launch apps downloaded from the Internet which have not been
@@ -300,7 +310,8 @@ int CScreensaver::launch_screensaver(RESULT* rp, PROCESS_REF& graphics_applicati
         fflush(m_gfx_Cleanup_IPC);
 
         if (graphics_application) {
-            launchedGfxApp(rp->graphics_exec_path, graphics_application, rp->slot);
+            graphicsAppStartTime = getDTime();
+            launchedGfxApp(rp->graphics_exec_path, rp->wu_name, graphics_application, rp->slot);
         }
 #else
         char* argv[3];
@@ -324,6 +335,7 @@ int CScreensaver::launch_screensaver(RESULT* rp, PROCESS_REF& graphics_applicati
 //
 int CScreensaver::terminate_v6_screensaver(PROCESS_REF graphics_application) {
 #ifdef __APPLE__
+    static bool in_terminate_v6_screensaver = false;
     pid_t thePID;
 
     // As of OS 10.15 (Catalina) screensavers can no longer launch apps
@@ -338,31 +350,41 @@ int CScreensaver::terminate_v6_screensaver(PROCESS_REF graphics_application) {
     // able to just call kill_program(graphics_application).
     //
     int ignore;
-
-    if (graphics_application == 0) return 0;
-
+    graphicsAppStartTime = 0;   // Prevent triggering markAsIncompatible in HasProcessExited()
     // MUTEX may help prevent crashes when terminating an older gfx app which
     // we were displaying using CGWindowListCreateImage under OS X >= 10.13
     // Also prevents reentry when called from our other thread
     pthread_mutex_lock(&saver_mutex);
 
     thePID = graphics_application;
-    // fprintf(stderr, "stopping pid %d\n", thePID);
+    if (in_terminate_v6_screensaver) {
+        pthread_mutex_unlock(&saver_mutex);
+        return 0;
+    }
+
+    in_terminate_v6_screensaver = true;
+   // print_to_log_file( "stopping pid %d\n", thePID);
     rpc->run_graphics_app("stop", thePID, gUserName);
 
     // Inform our helper app that we have stopped current graphics app
     fprintf(m_gfx_Cleanup_IPC, "0\n");
     fflush(m_gfx_Cleanup_IPC);
 
-    launchedGfxApp("", 0, -1);
-
     for (int i=0; i<200; i++) {
         boinc_sleep(0.01);      // Wait 2 seconds max
         if (HasProcessExited(graphics_application, ignore)) {
             break;
         }
     }
+    // For safety, call kill_process() even under Apple sandbox security
+    if (graphics_application) {
+        kill_process(graphics_application);
+    }
+
+    launchedGfxApp("", "", 0, -1);
+
     pthread_mutex_unlock(&saver_mutex);
+    in_terminate_v6_screensaver = false;
 #endif
 
 #ifdef _WIN32
@@ -377,10 +399,10 @@ int CScreensaver::terminate_v6_screensaver(PROCESS_REF graphics_application) {
             kill_process(graphics_application);
         }
     }
-#endif
 
     // For safety, call kill_process() even under Apple sandbox security
     kill_process(graphics_application);
+#endif
     return 0;
 }
 
@@ -436,7 +458,7 @@ int CScreensaver::launch_default_screensaver(char *dir_path, PROCESS_REF& graphi
     fflush(m_gfx_Cleanup_IPC);
 
     if (graphics_application) {
-        launchedGfxApp("boincscr", graphics_application, -1);
+        launchedGfxApp("boincscr", "", graphics_application, -1);
     }
 
     BOINCTRACE(_T("launch_default_screensaver returned %d\n"), retval);
@@ -540,6 +562,9 @@ DataMgmtProcType CScreensaver::DataManagementProc() {
     graphics_app_result_ptr = NULL;
 
 #ifdef __APPLE__
+    for (int i = 0; i < m_vIncompatibleGfxApps.size(); i++) {
+        free(m_vIncompatibleGfxApps[i]);
+    }
     m_vIncompatibleGfxApps.clear();
     default_ss_dir_path = "/Library/Application Support/BOINC Data";
     char shmem_name[MAXPATHLEN];
@@ -551,6 +576,9 @@ DataMgmtProcType CScreensaver::DataManagementProc() {
         chmod(shmem_name, 0666);
         ss_shmem->gfx_pid = 0;
         ss_shmem->gfx_slot = -1;
+        ss_shmem->major_version = 0;
+        ss_shmem->minor_version = 0;
+        ss_shmem->release = 0;
     }
 
     if (!IsUserMemberOfGroup(gUserName, "boinc_master")) canAccessProjectGFXApps = false;
@@ -680,11 +708,15 @@ DataMgmtProcType CScreensaver::DataManagementProc() {
                 // BOINCTRACE(_T("CScreensaver::Ending Default phase: now=%f, default_phase_start_time=%f, default_saver_duration_in_science_phase=%f\n"),
                 // dtime(), default_phase_start_time, default_saver_duration_in_science_phase);
                 ss_phase = SCIENCE_SS_PHASE;
-                default_phase_start_time = 0;
+               default_phase_start_time = 0;
                 default_saver_duration_in_science_phase = 0;
                 science_phase_start_time = dtime();
                 if (m_bDefault_gfx_running) {
                     default_saver_start_time_in_science_phase = science_phase_start_time;
+                    for (int i = 0; i < m_vIncompatibleGfxApps.size(); i++) {
+                        free(m_vIncompatibleGfxApps[i]);
+                    }
+                    m_vIncompatibleGfxApps.clear();
                 }
                 switch_to_default_gfx = false;
             }
@@ -945,7 +977,7 @@ DataMgmtProcType CScreensaver::DataManagementProc() {
                 m_bDefault_gfx_running = false;
                 m_bScience_gfx_running = false;
 #ifdef __APPLE__
-                launchedGfxApp("", 0, -1);
+                launchedGfxApp("", "", 0, -1);
 #endif
                 continue;
             }
@@ -976,6 +1008,12 @@ bool CScreensaver::HasProcessExited(pid_t pid, int &exitCode) {
     if (ss_shmem) {
         if (ss_shmem->gfx_pid != 0) return false;
         if (ss_shmem->gfx_slot > -1) { // -1 means Default GFX, which has no slot number
+            if (graphicsAppStartTime && ((getDTime() - graphicsAppStartTime) < 2)) {
+                if (graphics_app_result_ptr && graphics_app_result_ptr->graphics_exec_path) {
+                    markAsIncompatible(graphics_app_result_ptr->wu_name);
+
+                }
+            }
             // Graphics apps called by screensaver or Manager (via Show
             // Graphics button) now write files in their slot directory as
             // the logged in user, not boinc_master. This ugly hack tells
@@ -983,6 +1021,9 @@ bool CScreensaver::HasProcessExited(pid_t pid, int &exitCode) {
             rpc->run_graphics_app("stop", ss_shmem->gfx_slot, "");
             ss_shmem->gfx_pid = 0;
             ss_shmem->gfx_slot = -1;
+            ss_shmem->major_version = 0;
+            ss_shmem->minor_version = 0;
+            ss_shmem->release = 0;
         }
 
     }
@@ -1034,3 +1075,19 @@ void CScreensaver::GetDefaultDisplayPeriods(struct ss_periods &periods) {
         periods.GFXChangePeriod
     );
 }
+
+
+#ifdef __APPLE__
+// compareBOINCLibVersionTo(x, y) returns:
+// -1 if the library version is less than x.y
+//  0 if the library version is equal to x.y
+// +1 if the library version is lgreater than x.y
+int compareBOINCLibVersionTo(int toMajor, int toMinor) {
+    if (ss_shmem->major_version < toMajor) return -1;
+    if (ss_shmem->major_version > toMajor) return 1;
+    // if (major == toMajor) compare minor version numbers
+    if (ss_shmem->minor_version < toMinor) return -1;
+    if (ss_shmem->minor_version > toMinor) return 1;
+    return 0;
+}
+#endif