[core] A better way to launch daemon (#622)

core/magisk_module/post-fs-data.sh

@@ -135,12 +135,4 @@ if [ ! -z "${MISC_PATH}" ]; then
   start_log_catcher all "LSPosed:V XSharedPreferences:V LSPosed-Bridge:V LSPosedManager:V LSPosedService:V *:F" true ${LOG_VERBOSE}
 fi
 
-start_app_process() {
-  while true; do
-    if [ -S "/dev/socket/zygote" ]; then
-      nohup /system/bin/app_process -Djava.class.path=$(magisk --path)/.magisk/modules/riru_lsposed/framework/lspd.dex /system/bin org.lsposed.lspd.core.Main --nice-name=lspd >/dev/null 2>&1 & echo $! > /data/adb/lspd/daemon.pid
-      return
-    fi
-  done
-}
-start_app_process & echo $! > /data/adb/lspd/daemon.pid
+nohup /system/bin/app_process -Djava.class.path=$(magisk --path)/.magisk/modules/riru_lsposed/framework/lspd.dex /system/bin org.lsposed.lspd.core.Main --nice-name=lspd >/dev/null 2>&1

core/magisk_module/service.sh

@@ -19,14 +19,5 @@
 # Copyright (C) 2021 LSPosed Contributors
 #
 
-CMDLINE="$(cat /proc/$(cat /data/adb/lspd/daemon.pid)/cmdline)"
-
-# if still waiting for zygote, cmdline should be like:
-# $(magisk --path)/.magisk/busybox/busyboxsh/data/adb/modules/riru_lsposed/post-fs-data.sh
-# if service started, cmdline should be lspd
-# for other cases, post-fs-data.sh may not be executed properly
-if [ "${CMDLINE##*riru_lsposed/}" != "post-fs-data.sh" ] && [ "${CMDLINE##*=}" != "lspd" ]; then
-  log -pw -t "LSPosedService" "Got $CMDLINE"
-  log -pw -t "LSPosedService" "LSPosed daemon is not started properly. Try for a late start..."
-  nohup /system/bin/app_process -Djava.class.path=$(magisk --path)/.magisk/modules/riru_lsposed/framework/lspd.dex /system/bin org.lsposed.lspd.core.Main --nice-name=lspd >/dev/null 2>&1 & echo $! > /data/adb/lspd/daemon.pid
-fi
+# post-fs-data.sh may be blocked by other modules. retry to start this
+nohup /system/bin/app_process -Djava.class.path=$(magisk --path)/.magisk/modules/riru_lsposed/framework/lspd.dex /system/bin org.lsposed.lspd.core.Main --nice-name=lspd --from-service >/dev/null 2>&1

core/src/main/java/org/lsposed/lspd/core/Main.java

@@ -24,7 +24,6 @@ import android.annotation.SuppressLint;
 import android.app.ActivityThread;
 import android.content.pm.ApplicationInfo;
 import android.content.res.CompatibilityInfo;
-import android.ddm.DdmHandleAppName;
 import android.os.Environment;
 import android.os.IBinder;
 
@@ -33,6 +32,7 @@ import java.io.File;
 import de.robv.android.xposed.XposedBridge;
 import de.robv.android.xposed.XposedHelpers;
 import de.robv.android.xposed.XposedInit;
+
 import org.lsposed.lspd.config.LSPApplicationServiceClient;
 import org.lsposed.lspd.deopt.PrebuiltMethodsDeopter;
 import org.lsposed.lspd.hooker.HandleBindAppHooker;
@@ -75,6 +75,7 @@ public class Main {
                 SystemMainHooker.systemServerCL,
                 "startBootstrapServices", paramTypesAndCallback);
     }
+
     private static void installBootstrapHooks(boolean isSystem, String appDataDir) {
         // Initialize the Xposed framework
         try {
@@ -92,6 +93,7 @@ public class Main {
             Utils.logE("error loading module list", exception);
         }
     }
+
     private static void forkPostCommon(boolean isSystem, String appDataDir, String niceName) {
         // init logger
         YahfaHooker.init();
@@ -116,11 +118,6 @@ public class Main {
     }
 
     public static void main(String[] args) {
-        for (String arg : args) {
-            if (arg.equals("--debug")) {
-                DdmHandleAppName.setAppName("lspd", 0);
-            }
-        }
-        ServiceManager.start();
+        ServiceManager.start(args);
     }
 }

core/src/main/java/org/lsposed/lspd/service/ConfigManager.java

@@ -50,8 +50,12 @@ import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.channels.FileChannel;
+import java.nio.channels.FileLock;
 import java.nio.file.Files;
+import java.nio.file.OpenOption;
 import java.nio.file.StandardOpenOption;
+import java.nio.file.attribute.PosixFilePermissions;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -76,6 +80,7 @@ public class ConfigManager {
 
     private static final File basePath = new File("/data/adb/lspd");
     private static final File configPath = new File(basePath, "config");
+    private static final File lockPath = new File(basePath, "lock");
     private static final SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(new File(configPath, "modules_config.db"), null);
 
     boolean packageStarted = false;
@@ -97,6 +102,15 @@ public class ConfigManager {
     private static final File modulesLog = new File(logPath, "modules.log");
     private static final File oldModulesLog = new File(logPath, "modules.old.log");
     private static final File verboseLogPath = new File(logPath, "all.log");
+    private static FileLock locker = null;
+
+    static {
+        try {
+            Files.createDirectories(basePath.toPath());
+        } catch (IOException e) {
+            Log.e(TAG, Log.getStackTraceString(e));
+        }
+    }
 
     private final Handler cacheHandler;
 
@@ -165,6 +179,23 @@ public class ConfigManager {
         }
     }
 
+    public boolean tryLock() {
+        var openOptions = new HashSet<OpenOption>();
+        openOptions.add(StandardOpenOption.CREATE);
+        openOptions.add(StandardOpenOption.DELETE_ON_CLOSE);
+        openOptions.add(StandardOpenOption.WRITE);
+        var p = PosixFilePermissions.fromString("rw-------");
+        var permissions = PosixFilePermissions.asFileAttribute(p);
+
+        try {
+            var lockChannel = FileChannel.open(lockPath.toPath(), openOptions, permissions);
+            locker = lockChannel.tryLock();
+            return locker != null && locker.isValid();
+        } catch (Throwable e) {
+            return false;
+        }
+    }
+
     // for system server, cache is not yet ready, we need to query database for it
     public boolean shouldSkipSystemServer() {
         if (!SELinux.checkSELinuxAccess("u:r:system_server:s0", "u:r:system_server:s0", "process", "execmem")) {

core/src/main/java/org/lsposed/lspd/service/ServiceManager.java

@@ -20,6 +20,7 @@
 package org.lsposed.lspd.service;
 
 import android.content.Context;
+import android.ddm.DdmHandleAppName;
 import android.os.IBinder;
 import android.os.IServiceManager;
 import android.os.Looper;
@@ -55,7 +56,18 @@ public class ServiceManager {
     }
 
     // call by ourselves
-    public static void start() {
+    public static void start(String[] args) {
+        if (!ConfigManager.getInstance().tryLock()) return;
+
+        android.os.Process.killProcess(android.system.Os.getppid());
+        for (String arg : args) {
+            if (arg.equals("--debug")) {
+                DdmHandleAppName.setAppName("lspd", 0);
+            }
+            if (arg.equals("--from-service")) {
+                Log.w(TAG, "LSPosed daemon is not started properly. Try for a late start...");
+            }
+        }
         Log.i(TAG, "starting server...");
         Log.i(TAG, String.format("version %s (%s)", BuildConfig.VERSION_NAME, BuildConfig.VERSION_NAME));