Do not hardcode server path on the device

The path can be retrieved from the classpath.

PR #4416 <https://github.com/Genymobile/scrcpy/pull/4416>

Co-authored-by: Romain Vimont <rom@rom1v.com>
Signed-off-by: Romain Vimont <rom@rom1v.com>

server/src/main/java/com/genymobile/scrcpy/CleanUp.java

@@ -14,8 +14,6 @@ import java.io.IOException;
  */
 public final class CleanUp {
 
-    public static final String SERVER_PATH = "/data/local/tmp/scrcpy-server.jar";
-
     // A simple struct to be passed from the main process to the cleanup process
     public static class Config implements Parcelable {
 
@@ -135,13 +133,13 @@ public final class CleanUp {
         String[] cmd = {"app_process", "/", CleanUp.class.getName(), config.toBase64()};
 
         ProcessBuilder builder = new ProcessBuilder(cmd);
-        builder.environment().put("CLASSPATH", SERVER_PATH);
+        builder.environment().put("CLASSPATH", Server.SERVER_PATH);
         builder.start();
     }
 
     public static void unlinkSelf() {
         try {
-            new File(SERVER_PATH).delete();
+            new File(Server.SERVER_PATH).delete();
         } catch (Exception e) {
             Ln.e("Could not unlink server", e);
         }

server/src/main/java/com/genymobile/scrcpy/Server.java

@@ -3,12 +3,20 @@ package com.genymobile.scrcpy;
 import android.os.BatteryManager;
 import android.os.Build;
 
+import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
 public final class Server {
 
+    public static final String SERVER_PATH;
+    static {
+        String[] classPaths = System.getProperty("java.class.path").split(File.pathSeparator);
+        // By convention, scrcpy is always executed with the absolute path of scrcpy-server.jar as the first item in the classpath
+        SERVER_PATH = classPaths[0];
+    }
+
     private static class Completion {
         private int running;
         private boolean fatalError;