Fix the JvmOptions parsing of procfs cmdline

Author: jbachorik

components/environment/src/main/java/datadog/environment/JvmOptions.java

@@ -55,21 +55,30 @@ List<String> findVmOptions(String[] procfsCmdline) {
       List<String> vmOptions = new ArrayList<>();
       // Start at 1 to skip "java" command itself
       int index = 1;
-      // Look for main class or "-jar", end of VM options
+      // Look for first self-standing argument that is not prefixed with "-" or end of VM options
+      // Skip "-jar" and the jar file
       // Simultaneously, collect all arguments in the VM options
       for (; index < procfsCmdline.length; index++) {
         String argument = procfsCmdline[index];
-        if (argument.startsWith("@")) {
-          vmOptions.addAll(getArgumentsFromFile(argument));
-        } else {
+        if ("-jar".equals(argument)) {
+          // skip "-jar" and the jar file
+          index++;
+          continue;
+        } else if ("-cp".equals(argument)) {
+          // slurp '-cp' and the classpath
           vmOptions.add(argument);
-        }
-        if (!argument.startsWith("-") || "-jar".equals(argument)) {
           if (index + 1 < procfsCmdline.length) {
-            vmOptions.add(procfsCmdline[index + 1]); // jar file or the main class
+            argument = procfsCmdline[++index];
           }
+        } else if (!argument.startsWith("-")) {
+          // end of VM options
           break;
         }
+        if (argument.startsWith("@")) {
+          vmOptions.addAll(getArgumentsFromFile(argument));
+        } else {
+          vmOptions.add(argument);
+        }
       }
       // Insert JDK_JAVA_OPTIONS at the start if present and supported
       List<String> jdkJavaOptions = getJdkJavaOptions();

components/environment/src/test/java/datadog/environment/JvmOptionsTest.java

@@ -122,12 +122,17 @@ private static Stream<Arguments> procFsCmdLine() {
         arguments(
             "Java with JAR and options",
             new String[]{"java", "-Xmx512m", "-Xms256m", "-jar", "app.jar"},
-            asList("-Xmx512m", "-Xms256m", "-jar", "app.jar")
+            asList("-Xmx512m", "-Xms256m")
         ),
         arguments(
             "Java from class and options",
             new String[]{"java", "-Xmx512m", "-Xms256m", "-cp", "app.jar", "Main"},
-            asList("-Xmx512m", "-Xms256m", "-cp", "app.jar", "Main")
+            asList("-Xmx512m", "-Xms256m", "-cp", "app.jar")
+        ),
+        arguments(
+            "Java from class and options, mixed",
+            new String[]{"java", "-Xms256m", "-cp", "app.jar", "-Xmx512m", "Main"},
+            asList("-Xms256m", "-cp", "app.jar", "-Xmx512m")
         ));
     // spotless:on
   }