use root to avoid being killed by sb

Author: Lessica

HUDApp.mm

@@ -1,4 +1,5 @@
 #import <cstddef>
+#import <cstring>
 #import <cstdlib>
 #import <dlfcn.h>
 #import <spawn.h>
@@ -42,19 +43,6 @@ - (void)__completeAndRunAsPlugin;
 - (void)_run;
 @end
 
-@interface FBSUIApplicationWorkspace : NSObject
-- (instancetype)initWithSerialQueue:(id)arg1;
-- (void)setDelegate:(id)arg1;
-@end
-
-@interface MyFBSUIApplicationWorkspaceDelegate : NSObject
-@end
-
-@implementation MyFBSUIApplicationWorkspaceDelegate
-- (void)workspaceShouldExit:(FBSUIApplicationWorkspace *)arg1 {}
-- (void)workspace:(FBSUIApplicationWorkspace *)arg1 didLaunchWithCompletion:(void (^)(id))arg2 {}
-@end
-
 
 #pragma mark -
 
@@ -68,41 +56,91 @@ static __used void _HUDEventCallback(void *target, void *refcon, IOHIDServiceRef
 }
 
 
+#pragma mark -
+
+static NSString *_cachesDirectoryPath = nil;
+static NSString *_hudPIDFilePath = nil;
+static NSString *GetPIDFilePath(void)
+{
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        _cachesDirectoryPath = 
+        [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];
+        _hudPIDFilePath = [_cachesDirectoryPath stringByAppendingPathComponent:@"hud.pid"];
+    });
+    return _hudPIDFilePath;
+}
+
+
 #pragma mark -
 
 int main(int argc, char *argv[])
 {
     @autoreleasepool
     {
-        os_log_debug(OS_LOG_DEFAULT, "Launched with bundle identifier %{public}@, uid = %{public}d", NSBundle.mainBundle.bundleIdentifier, getuid());
+        os_log_debug(OS_LOG_DEFAULT, "launched argc %{public}d, argv[1] %{public}s", argc, argc > 1 ? argv[1] : "NULL");
 
-        if (argc < 2 || strcmp(argv[1], "-hud") != 0)
+        if (argc <= 1)
             return UIApplicationMain(argc, argv, @"MainApplication", @"MainApplicationDelegate");
 
-        [UIScreen initialize];
-        CFRunLoopGetCurrent();
-
-        GSInitialize();
-        BKSDisplayServicesStart();
-        UIApplicationInitialize();
-
-        [NSRunLoop currentRunLoop];
-        BKSHIDEventRegisterEventCallback(_HUDEventCallback);
-
-        GSEventInitialize(0);
-        GSEventPushRunLoopMode(kCFRunLoopDefaultMode);
-
-        UIApplicationInstantiateSingleton(objc_getClass("HUDMainApplication"));
-        static id<UIApplicationDelegate> appDelegate = [[objc_getClass("HUDMainApplicationDelegate") alloc] init];
-        [UIApplication.sharedApplication setDelegate:appDelegate];
-        [UIApplication.sharedApplication _accessibilityInit];
-        [UIApplication.sharedApplication __completeAndRunAsPlugin];
-
-        static FBSUIApplicationWorkspace *workspace = 
-            [[objc_getClass("FBSUIApplicationWorkspace") alloc] initWithSerialQueue:[UIApplication.sharedApplication _systemAnimationFenceExemptQueue]];
-        [workspace setDelegate:[MyFBSUIApplicationWorkspaceDelegate new]];
-
-        CFRunLoopRun();
-        return EXIT_SUCCESS;
+        if (strcmp(argv[1], "-hud") == 0)
+        {
+            NSString *pidString = [NSString stringWithFormat:@"%d", getpid()];
+            [pidString writeToFile:GetPIDFilePath()
+                        atomically:YES
+                          encoding:NSUTF8StringEncoding
+                             error:nil];
+            
+            [UIScreen initialize];
+            CFRunLoopGetCurrent();
+
+            GSInitialize();
+            BKSDisplayServicesStart();
+            UIApplicationInitialize();
+
+            [NSRunLoop currentRunLoop];
+            BKSHIDEventRegisterEventCallback(_HUDEventCallback);
+
+            GSEventInitialize(0);
+            GSEventPushRunLoopMode(kCFRunLoopDefaultMode);
+
+            UIApplicationInstantiateSingleton(objc_getClass("HUDMainApplication"));
+            static id<UIApplicationDelegate> appDelegate = [[objc_getClass("HUDMainApplicationDelegate") alloc] init];
+            [UIApplication.sharedApplication setDelegate:appDelegate];
+            [UIApplication.sharedApplication _accessibilityInit];
+            [UIApplication.sharedApplication __completeAndRunAsPlugin];
+            
+            CFRunLoopRun();
+            return EXIT_SUCCESS;
+        }
+        else if (strcmp(argv[1], "-exit") == 0)
+        {
+            NSString *pidString = [NSString stringWithContentsOfFile:GetPIDFilePath()
+                                                            encoding:NSUTF8StringEncoding
+                                                               error:nil];
+            
+            if (pidString)
+            {
+                pid_t pid = (pid_t)[pidString intValue];
+                kill(pid, SIGKILL);
+                unlink(GetPIDFilePath().UTF8String);
+            }
+
+            return EXIT_SUCCESS;
+        }
+        else if (strcmp(argv[1], "-check") == 0)
+        {
+            NSString *pidString = [NSString stringWithContentsOfFile:GetPIDFilePath()
+                                                            encoding:NSUTF8StringEncoding
+                                                               error:nil];
+            
+            if (pidString)
+            {
+                pid_t pid = (pid_t)[pidString intValue];
+                int killed = kill(pid, 0);
+                return (killed == 0 ? EXIT_FAILURE : EXIT_SUCCESS);
+            }
+            else return EXIT_SUCCESS;  // No PID file, so HUD is not running
+        }
     }
 }