From b12daa41e23eaac2777a8f89ef279963d0e6f7a0 Mon Sep 17 00:00:00 2001
From: Oli Gillespie <ogillespie@openjdk.org>
Date: Mon, 2 Mar 2026 10:16:57 +0000
Subject: [PATCH] 8378110: Add -XX: prefix to settings-file flags in
 RuntimeMXBean.getInputArguments()

Reviewed-by: kevinw, dholmes
---
 src/hotspot/share/prims/jvm.cpp               |  4 +-
 .../RuntimeMXBean/InputArgument.java          | 53 +++++++++++++------
 2 files changed, 39 insertions(+), 18 deletions(-)

diff --git a/src/hotspot/share/prims/jvm.cpp b/src/hotspot/share/prims/jvm.cpp
index 2b3a2966c27..423e1a5a1f4 100644
--- a/src/hotspot/share/prims/jvm.cpp
+++ b/src/hotspot/share/prims/jvm.cpp
@@ -3641,7 +3641,9 @@ JVM_ENTRY(jobjectArray, JVM_GetVmArguments(JNIEnv *env))
 
   int index = 0;
   for (int j = 0; j < num_flags; j++, index++) {
-    Handle h = java_lang_String::create_from_platform_dependent_str(vm_flags[j], CHECK_NULL);
+    stringStream prefixed;
+    prefixed.print("-XX:%s", vm_flags[j]);
+    Handle h = java_lang_String::create_from_platform_dependent_str(prefixed.base(), CHECK_NULL);
     result_h->obj_at_put(index, h());
   }
   for (int i = 0; i < num_args; i++, index++) {
diff --git a/test/jdk/java/lang/management/RuntimeMXBean/InputArgument.java b/test/jdk/java/lang/management/RuntimeMXBean/InputArgument.java
index 66c3d3f41f5..0e7609b86ed 100644
--- a/test/jdk/java/lang/management/RuntimeMXBean/InputArgument.java
+++ b/test/jdk/java/lang/management/RuntimeMXBean/InputArgument.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -62,41 +62,60 @@
  * @run main/othervm -Dprops=something InputArgument -Dprops=something
  */
 
+/*
+ * @test
+ * @bug     8378110
+ * @summary RuntimeMXBean.getInputArguments() handling of flags from settings file.
+ *
+ * @run driver InputArgument generateFlagsFile
+ * @run main/othervm -XX:+UseFastJNIAccessors -XX:Flags=InputArgument.flags InputArgument
+ * -XX:+UseFastJNIAccessors -XX:-UseG1GC -XX:+UseParallelGC -XX:MaxHeapSize=100M
+ */
+
 import java.lang.management.*;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 import java.util.List;
 import java.util.ListIterator;
 
 public class InputArgument {
     private static RuntimeMXBean rm = ManagementFactory.getRuntimeMXBean();
-    private static String vmOption = null;
 
     public static void main(String args[]) throws Exception {
-        // set the expected input argument
-        if (args.length > 0) {
-            vmOption = args[0];
-        }
-
-        List<String> options = rm.getInputArguments();
-        if (vmOption == null) {
+        if (args.length == 1 && "generateFlagsFile".equals(args[0])) {
+            generateFlagsFile();
             return;
         }
 
-        boolean testFailed = true;
+        String[] vmOptions = args;
+        List<String> options = rm.getInputArguments();
         System.out.println("Number of arguments = " + options.size());
         int i = 0;
         for (String arg : options) {
             System.out.println("Input arg " + i + " = " + arg);
             i++;
-            if (arg.equals(vmOption)) {
-                testFailed = false;
-                break;
-            }
         }
-        if (testFailed) {
-            throw new RuntimeException("TEST FAILED: " +
-                "VM option " + vmOption + " not found");
+
+        for (String expected : vmOptions) {
+            boolean found = false;
+            for (String arg : options) {
+                if (arg.equals(expected)) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                throw new RuntimeException("TEST FAILED: " +
+                    "VM option " + expected + " not found");
+            }
         }
 
         System.out.println("Test passed.");
     }
+
+    private static void generateFlagsFile() throws Exception {
+        // 3 types of flag; both boolean cases and 1 numeric
+        Files.writeString(Paths.get("", "InputArgument.flags"),
+            String.format("-UseG1GC%n+UseParallelGC%nMaxHeapSize=100M%n"));
+    }
 }