changeset 39706:8b8fd966478b

8159145: Add JVMTI function GetNamedModule Summary: Introduce function GetNamedModule with a jtreg test coverage Reviewed-by: alanb, ctornqvi, hseigel, jiangli, dholmes, dcubed
author sspitsyn
date Sat, 09 Jul 2016 19:20:38 -0700
parents 55baa0ddef24
children 4974c8df2532
files hotspot/make/test/JtregNative.gmk hotspot/src/share/vm/classfile/modules.cpp hotspot/src/share/vm/classfile/modules.hpp hotspot/src/share/vm/prims/jvmti.xml hotspot/src/share/vm/prims/jvmtiEnv.cpp hotspot/test/serviceability/jvmti/GetNamedModule/MyPackage/GetNamedModuleTest.java hotspot/test/serviceability/jvmti/GetNamedModule/libGetNamedModuleTest.c
diffstat 7 files changed, 572 insertions(+), 7 deletions(-) [+]
line wrap: on
line diff
--- a/hotspot/make/test/JtregNative.gmk	Fri Jul 08 12:17:10 2016 -0700
+++ b/hotspot/make/test/JtregNative.gmk	Sat Jul 09 19:20:38 2016 -0700
@@ -51,6 +51,7 @@
     $(HOTSPOT_TOPDIR)/test/compiler/floatingpoint/ \
     $(HOTSPOT_TOPDIR)/test/compiler/calls \
     $(HOTSPOT_TOPDIR)/test/compiler/native \
+    $(HOTSPOT_TOPDIR)/test/serviceability/jvmti/GetNamedModule \
     $(HOTSPOT_TOPDIR)/test/testlibrary/jvmti \
     #
 
@@ -64,6 +65,7 @@
 ifeq ($(TOOLCHAIN_TYPE), solstudio)
     BUILD_HOTSPOT_JTREG_LIBRARIES_LDFLAGS_liboverflow := -lc
     BUILD_HOTSPOT_JTREG_LIBRARIES_LDFLAGS_libSimpleClassFileLoadHook := -lc
+    BUILD_HOTSPOT_JTREG_LIBRARIES_LDFLAGS_libGetNamedModuleTest := -lc
 endif
 
 BUILD_HOTSPOT_JTREG_OUTPUT_DIR := $(BUILD_OUTPUT)/support/test/hotspot/jtreg/native
--- a/hotspot/src/share/vm/classfile/modules.cpp	Fri Jul 08 12:17:10 2016 -0700
+++ b/hotspot/src/share/vm/classfile/modules.cpp	Sat Jul 09 19:20:38 2016 -0700
@@ -820,6 +820,28 @@
 }
 
 
+jobject Modules::get_named_module(Handle h_loader, const char* package_str, TRAPS) {
+  assert(ModuleEntryTable::javabase_defined(),
+         "Attempt to call get_named_module before java.base is defined");
+  assert(h_loader.is_null() || java_lang_ClassLoader::is_subclass(h_loader->klass()),
+         "Class loader is not a subclass of java.lang.ClassLoader");
+  assert(package_str != NULL, "the package_str should not be NULL");
+
+  if (strlen(package_str) == 0) {
+    return NULL;
+  }
+  TempNewSymbol package_sym = SymbolTable::new_symbol(package_str, CHECK_NULL);
+  const PackageEntry* const pkg_entry =
+    get_package_entry_by_name(package_sym, h_loader, THREAD);
+  const ModuleEntry* const module_entry = (pkg_entry != NULL ? pkg_entry->module() : NULL);
+
+  if (module_entry != NULL && module_entry->module() != NULL && module_entry->is_named()) {
+    return JNIHandles::make_local(THREAD, JNIHandles::resolve(module_entry->module()));
+  }
+  return NULL;
+}
+
+
 // This method is called by JFR and by the above method.
 jobject Modules::get_module(Symbol* package_name, Handle h_loader, TRAPS) {
   const PackageEntry* const pkg_entry =
--- a/hotspot/src/share/vm/classfile/modules.hpp	Fri Jul 08 12:17:10 2016 -0700
+++ b/hotspot/src/share/vm/classfile/modules.hpp	Sat Jul 09 19:20:38 2016 -0700
@@ -121,6 +121,7 @@
   // IllegalArgumentException is thrown if loader is neither null nor a subtype of
   // java/lang/ClassLoader.
   static jobject get_module_by_package_name(jobject loader, jstring package, TRAPS);
+  static jobject get_named_module(Handle h_loader, const char* package, TRAPS);
 
   // If package is defined by loader, return the
   // java.lang.reflect.Module object for the module in which the package is defined.
--- a/hotspot/src/share/vm/prims/jvmti.xml	Fri Jul 08 12:17:10 2016 -0700
+++ b/hotspot/src/share/vm/prims/jvmti.xml	Sat Jul 09 19:20:38 2016 -0700
@@ -6509,6 +6509,59 @@
       <errors>
       </errors>
     </function>
+
+    <function id="GetNamedModule" num="40" since="9">
+      <synopsis>Get Named Module</synopsis>
+      <description>
+        Return the <code>java.lang.reflect.Module</code> object for a named
+        module defined to a class loader that contains a given package.
+        The module is returned via <code>module_ptr</code>.
+        <p/>
+        If a named module is defined to the class loader and it
+        contains the package then that named module is returned,
+        otherwise <code>NULL</code> is returned.
+        <p/>
+      </description>
+      <origin>new</origin>
+      <capabilities>
+      </capabilities>
+      <parameters>
+        <param id="class_loader">
+          <ptrtype>
+            <jobject/>
+            <nullok>the bootstrap loader is assumed</nullok>
+          </ptrtype>
+          <description>
+            A class loader.
+            If the <code>class_loader</code> is not <code>NULL</code>
+            or a subclass of <code>java.lang.ClassLoader</code>
+            this function returns
+            <errorlink id="JVMTI_ERROR_ILLEGAL_ARGUMENT"></errorlink>.
+          </description>
+        </param>
+        <param id="package_name">
+          <inbuf><char/></inbuf>
+          <description>
+            The name of the package, encoded as a
+            <internallink id="mUTF">modified UTF-8</internallink> string.
+            The package name is in internal form (JVMS 4.2.1);
+            identifiers are separated by forward slashes rather than periods.
+          </description>
+        </param>
+        <param id="module_ptr">
+          <outptr><jobject/></outptr>
+          <description>
+            On return, points to a <code>java.lang.reflect.Module</code> object
+            or points to <code>NULL</code>.
+          </description>
+        </param>
+      </parameters>
+      <errors>
+        <error id="JVMTI_ERROR_ILLEGAL_ARGUMENT">
+          If class loader is not <code>NULL</code> and is not a class loader object.
+        </error>
+      </errors>
+    </function>
   </category>
 
   <category id="class" label="Class">
@@ -12462,6 +12515,14 @@
     <code>new_class_data</code> has been set, it becomes the 
     <code>class_data</code> for the next agent.
     <p/>
+    When handling a class load in the live phase, then the
+    <functionlink id="GetNamedModule"></functionlink>
+    function can be used to map class loader and a package name to a module.
+    When a class is being redefined or retransformed then
+    <code>class_being_redefined</code> is non <code>NULL</code> and so
+    the JNI <code>GetModule</code> function can also be used
+    to obtain the Module.
+    <p/>
     The order that this event is sent to each environment differs
     from other events.
     This event is sent to environments in the following order:
@@ -14427,20 +14488,15 @@
   <change date="19 June 2013" version="1.2.3">
       Added support for statically linked agents.
   </change>
-  <change date="20 January 2016" version="9.0.0">
+  <change date="5 July 2016" version="9.0.0">
       Support for modules:
        - The majorversion is 9 now
        - The ClassFileLoadHook events are not sent during the primordial phase anymore.
        - Add new function GetAllModules
-  </change>
-  <change date="17 February 2016" version="9.0.0">
-      Support for modules:
        - Add new capability can_generate_early_vmstart
        - Allow CompiledMethodLoad events at start phase
-  </change>
-  <change date="14 April 2016" version="9.0.0">
-      Support for modules:
        - Add new capability can_generate_early_class_hook_events
+       - Add new function GetNamedModule
   </change>
 </changehistory>
 
--- a/hotspot/src/share/vm/prims/jvmtiEnv.cpp	Fri Jul 08 12:17:10 2016 -0700
+++ b/hotspot/src/share/vm/prims/jvmtiEnv.cpp	Sat Jul 09 19:20:38 2016 -0700
@@ -24,6 +24,7 @@
 
 #include "precompiled.hpp"
 #include "classfile/classLoaderExt.hpp"
+#include "classfile/modules.hpp"
 #include "classfile/systemDictionary.hpp"
 #include "classfile/vmSymbols.hpp"
 #include "interpreter/bytecodeStream.hpp"
@@ -201,6 +202,28 @@
 } /* end GetAllModules */
 
 
+// class_loader - NULL is a valid value, must be pre-checked
+// package_name - pre-checked for NULL
+// module_ptr - pre-checked for NULL
+jvmtiError
+JvmtiEnv::GetNamedModule(jobject class_loader, const char* package_name, jobject* module_ptr) {
+  JavaThread* THREAD = JavaThread::current(); // pass to macros
+  ResourceMark rm(THREAD);
+
+  Handle h_loader (THREAD, JNIHandles::resolve(class_loader));
+  // Check that loader is a subclass of java.lang.ClassLoader.
+  if (h_loader.not_null() && !java_lang_ClassLoader::is_subclass(h_loader->klass())) {
+    return JVMTI_ERROR_ILLEGAL_ARGUMENT;
+  }
+  jobject module = Modules::get_named_module(h_loader, package_name, THREAD);
+  if (HAS_PENDING_EXCEPTION) {
+    CLEAR_PENDING_EXCEPTION;
+    return JVMTI_ERROR_INTERNAL; // unexpected exception
+  }
+  *module_ptr = module;
+  return JVMTI_ERROR_NONE;
+} /* end GetNamedModule */
+
   //
   // Class functions
   //
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/serviceability/jvmti/GetNamedModule/MyPackage/GetNamedModuleTest.java	Sat Jul 09 19:20:38 2016 -0700
@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2016, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package MyPackage;
+
+/**
+ * @test
+ * @summary Verifies the JVMTI GetNamedModule API
+ * @compile GetNamedModuleTest.java
+ * @run main/othervm/native -agentlib:GetNamedModuleTest MyPackage.GetNamedModuleTest
+ */
+
+import java.io.PrintStream;
+
+public class GetNamedModuleTest {
+
+    static {
+        try {
+            System.loadLibrary("GetNamedModuleTest");
+        } catch (UnsatisfiedLinkError ule) {
+            System.err.println("Could not load GetNamedModuleTest library");
+            System.err.println("java.library.path: "
+                + System.getProperty("java.library.path"));
+            throw ule;
+        }
+    }
+
+    native static int check();
+
+    public static void main(String args[]) {
+        int status = check();
+        if (status != 0) {
+            throw new RuntimeException("Non-zero status returned from the agent: " + status);
+        }
+    }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/serviceability/jvmti/GetNamedModule/libGetNamedModuleTest.c	Sat Jul 09 19:20:38 2016 -0700
@@ -0,0 +1,405 @@
+/*
+ * Copyright (c) 2016, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include "jvmti.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef JNI_ENV_ARG
+
+#ifdef __cplusplus
+#define JNI_ENV_ARG(x, y) y
+#define JNI_ENV_PTR(x) x
+#else
+#define JNI_ENV_ARG(x,y) x, y
+#define JNI_ENV_PTR(x) (*x)
+#endif
+
+#endif
+
+#define TranslateError(err) "JVMTI error"
+
+#define PASSED 0
+#define FAILED 2
+
+static const char *EXC_CNAME = "java/lang/Exception";
+static const char* MOD_CNAME = "Ljava/lang/reflect/Module;";
+
+static jvmtiEnv *jvmti = NULL;
+static jint result = PASSED;
+static jboolean printdump = JNI_FALSE;
+
+static jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved);
+
+JNIEXPORT
+jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {
+    return Agent_Initialize(jvm, options, reserved);
+}
+
+JNIEXPORT
+jint JNICALL Agent_OnAttach(JavaVM *jvm, char *options, void *reserved) {
+    return Agent_Initialize(jvm, options, reserved);
+}
+
+JNIEXPORT
+jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved) {
+    return JNI_VERSION_1_8;
+}
+
+static
+jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) {
+    jint res;
+
+    if (options != NULL && strcmp(options, "printdump") == 0) {
+        printdump = JNI_TRUE;
+    }
+
+    res = JNI_ENV_PTR(jvm)->GetEnv(JNI_ENV_ARG(jvm, (void **) &jvmti),
+        JVMTI_VERSION_9);
+    if (res != JNI_OK || jvmti == NULL) {
+        printf("    Error: wrong result of a valid call to GetEnv!\n");
+        return JNI_ERR;
+    }
+
+    return JNI_OK;
+}
+
+static
+jint throw_exc(JNIEnv *env, char *msg) {
+    jclass exc_class = JNI_ENV_PTR(env)->FindClass(JNI_ENV_ARG(env, EXC_CNAME));
+
+    if (exc_class == NULL) {
+        printf("throw_exc: Error in FindClass(env, %s)\n", EXC_CNAME);
+        return -1;
+    }
+    return JNI_ENV_PTR(env)->ThrowNew(JNI_ENV_ARG(env, exc_class), msg);
+}
+
+static
+jobject get_class_loader(jclass cls) {
+    jvmtiError err = JVMTI_ERROR_NONE;
+    jobject loader = NULL;
+
+    if (printdump == JNI_TRUE) {
+        printf(">>> getting class loader ...\n");
+    }
+    err = (*jvmti)->GetClassLoader(jvmti, cls, &loader);
+    if (err != JVMTI_ERROR_NONE) {
+        printf("    Error in GetClassLoader: %s (%d)\n", TranslateError(err), err);
+    }
+    return loader;
+}
+
+static
+jclass jlrM(JNIEnv *env) {
+    jclass cls = NULL;
+
+    cls = JNI_ENV_PTR(env)->FindClass(JNI_ENV_ARG(env, MOD_CNAME));
+    if (cls == NULL) {
+        printf("    Error in JNI FindClass: %s\n", MOD_CNAME);
+    }
+    return cls;
+}
+
+jmethodID
+get_method(JNIEnv *env, jclass clazz, const char * name, const char *sig) {
+    jmethodID method = NULL;
+
+    method = JNI_ENV_PTR(env)->GetMethodID(JNI_ENV_ARG(env, clazz), name, sig);
+    if (method == NULL) {
+        printf("    Error in JNI GetMethodID %s with signature %s", name, sig);
+    }
+    return method;
+}
+
+static
+jobject get_module_loader(JNIEnv *env, jobject module) {
+    static jmethodID cl_method = NULL;
+    jobject loader = NULL;
+
+    if (cl_method == NULL) {
+        cl_method = get_method(env, jlrM(env), "getClassLoader", "()Ljava/lang/ClassLoader;");
+    }
+    loader = (jobject)JNI_ENV_PTR(env)->CallObjectMethod(JNI_ENV_ARG(env, module), cl_method);
+    return loader;
+}
+
+static
+const char* get_module_name(JNIEnv *env, jobject module) {
+    static jmethodID method = NULL;
+    jobject loader = NULL;
+    jstring jstr = NULL;
+    const char *name = NULL;
+    const char *nstr = NULL;
+
+    if (method == NULL) {
+        method = get_method(env, jlrM(env), "getName", "()Ljava/lang/String;");
+    }
+    jstr = (jstring)JNI_ENV_PTR(env)->CallObjectMethod(JNI_ENV_ARG(env, module), method);
+    if (jstr != NULL) {
+        name = JNI_ENV_PTR(env)->GetStringUTFChars(JNI_ENV_ARG(env, jstr), NULL);
+    }
+    loader = get_module_loader(env, module);
+    nstr = (name == NULL) ? "<UNNAMED>" : name;
+    printf("    loader: %p, module: %p, name: %s\n", loader, module, nstr);
+    return name;
+}
+
+static
+jvmtiError get_module(JNIEnv *env,
+                      jobject loader,
+                      const char* pkg_name,
+                      jobject* module_ptr,
+                      const char** mod_name_ptr) {
+    jvmtiError err = JVMTI_ERROR_NONE;
+    const char* name = (pkg_name == NULL) ? "<NULL>" : pkg_name;
+
+    printf(">>> getting module by loader %p and package \"%s\"\n", loader, name);
+    *mod_name_ptr = NULL;
+    err = (*jvmti)->GetNamedModule(jvmti, loader, pkg_name, module_ptr);
+    if (err != JVMTI_ERROR_NONE) {
+        printf("    Error in GetNamedModule for package \"%s\": %s (%d)\n",
+               pkg_name, TranslateError(err), err);
+        return err;
+    }
+    printf("    returned module: %p\n", *module_ptr);
+    if (*module_ptr == NULL) { // named module was not found
+        return err;
+    }
+    *mod_name_ptr = get_module_name(env, *module_ptr);
+    return err;
+}
+
+static
+jint get_all_modules(JNIEnv *env) {
+    jvmtiError err;
+    jint cnt = -1;
+    jint idx = 0;
+    jobject* modules;
+
+    printf(">>> Inspecting modules with GetAllModules\n");
+    err = (*jvmti)->GetAllModules(jvmti, &cnt, &modules);
+    if (err != JVMTI_ERROR_NONE) {
+        printf("Error in GetAllModules: %d\n", err);
+        return -1;
+    }
+    for (idx = 0; idx < cnt; ++idx) {
+        get_module_name(env, modules[idx]);
+    }
+    return cnt;
+}
+
+static
+jint check_bad_loader(JNIEnv *env, jobject loader) {
+    jvmtiError err = JVMTI_ERROR_NONE;
+    jobject module = NULL;
+    const char* mod_name = NULL;
+
+    err = get_module(env, loader, "", &module, &mod_name);
+    if (err != JVMTI_ERROR_ILLEGAL_ARGUMENT) {
+        return FAILED;
+    }
+    printf("    got expected JVMTI_ERROR_ILLEGAL_ARGUMENT for bad loader\n");
+    return PASSED;
+}
+
+static
+jint check_system_loader(JNIEnv *env, jobject loader) {
+    jvmtiError err = JVMTI_ERROR_NONE;
+    jobject module = NULL;
+    const char* exp_name = NULL;
+    const char* mod_name = NULL;
+
+    // NULL pointer for package name
+    err = get_module(env, loader, NULL, &module, &mod_name);
+    if (err != JVMTI_ERROR_NULL_POINTER) {
+        throw_exc(env, "check #SN1: failed to return JVMTI_ERROR_NULL_POINTER for NULL package");
+        return FAILED;
+    }
+
+    // NULL pointer for module_ptr
+    err = (*jvmti)->GetNamedModule(jvmti, loader, "", NULL);
+    if (err != JVMTI_ERROR_NULL_POINTER) {
+        throw_exc(env, "check #SN2: failed to return JVMTI_ERROR_NULL_POINTER for NULL module_ptr");
+        return FAILED;
+    }
+
+    // Unnamed/default package ""
+    err = get_module(env, loader, "", &module, &mod_name);
+    if (err != JVMTI_ERROR_NONE) {
+        throw_exc(env, "check #S1: failed to return JVMTI_ERROR_NONE for default package");
+        return FAILED;
+    }
+    if (module != NULL || mod_name != NULL) {
+        throw_exc(env, "check #S2: failed to return NULL-module for default package");
+        return FAILED;
+    }
+
+    // Test package: MyPackage
+    err = get_module(env, loader, "MyPackage", &module, &mod_name);
+    if (err != JVMTI_ERROR_NONE) {
+        throw_exc(env, "check #S3: failed to return JVMTI_ERROR_NONE for MyPackage");
+        return FAILED;
+    }
+    if (module != NULL || mod_name != NULL) {
+        throw_exc(env, "check #S4: failed to return NULL-module for MyPackage");
+        return FAILED;
+    }
+
+    // Package: com/sun/jdi
+    exp_name = "jdk.jdi";
+    err = get_module(env, loader, "com/sun/jdi", &module, &mod_name);
+    if (err != JVMTI_ERROR_NONE) {
+        throw_exc(env, "check #S5: failed to return JVMTI_ERROR_NONE for test package");
+        return FAILED;
+    }
+    if (module == NULL || mod_name == NULL) {
+        throw_exc(env, "check #S6: failed to return named module for com/sun/jdi package");
+        return FAILED;
+    }
+    if (strcmp(mod_name, exp_name) != 0) {
+        printf("check #S7: failed to return right module, expected: %s, returned: %s\n",
+               exp_name, mod_name);
+        throw_exc(env, "check #S7: failed to return jdk.jdi module for com/sun/jdi package");
+        return FAILED;
+    }
+
+    // Non-existing package: "bad/package/name"
+    err = get_module(env, loader, "bad/package/name", &module, &mod_name);
+    if (err != JVMTI_ERROR_NONE) {
+        throw_exc(env, "check #S8: failed to return JVMTI_ERROR_NONE for bad package");
+        return FAILED;
+    }
+    if (module != NULL || mod_name != NULL) {
+        throw_exc(env, "check #S9: failed to return NULL-module for bad package");
+        return FAILED;
+    }
+    return PASSED;
+}
+
+static
+jint check_bootstrap_loader(JNIEnv *env, jobject loader) {
+    jvmtiError err = JVMTI_ERROR_NONE;
+    jobject module = NULL;
+    const char* exp_name = NULL;
+    const char* mod_name = NULL;
+
+    // NULL pointer for package name
+    err = get_module(env, loader, NULL, &module, &mod_name);
+    if (err != JVMTI_ERROR_NULL_POINTER) {
+        throw_exc(env, "check #BN1: failed to return JVMTI_ERROR_NULL_POINTER for NULL package");
+        return FAILED;
+    }
+
+    // NULL pointer for module_ptr
+    err = (*jvmti)->GetNamedModule(jvmti, loader, "", NULL);
+    if (err != JVMTI_ERROR_NULL_POINTER) {
+        throw_exc(env, "check #BN2: failed to return JVMTI_ERROR_NULL_POINTER for NULL module_ptr");
+        return FAILED;
+    }
+
+    // Unnamed/default package ""
+    err = get_module(env, loader, "", &module, &mod_name);
+    if (err != JVMTI_ERROR_NONE) {
+        throw_exc(env, "check #B1: failed to return JVMTI_ERROR_NONE for default package");
+        return FAILED;
+    }
+    if (module != NULL || mod_name != NULL) {
+        throw_exc(env, "check #B2: failed to return NULL-module for default package");
+        return FAILED;
+    }
+
+    // Normal package from java.base module: "java/lang"
+    exp_name = "java.base";
+    err = get_module(env, loader, "java/lang", &module, &mod_name);
+    if (err != JVMTI_ERROR_NONE) {
+        throw_exc(env, "check #B3: failed to return JVMTI_ERROR_NONE for java/lang package");
+        return FAILED;
+    }
+    if (module == NULL || mod_name == NULL) {
+        throw_exc(env, "check #B4: failed to return named module for java/lang package");
+        return FAILED;
+    }
+    if (strcmp(exp_name, mod_name) != 0) {
+        printf("check #B5: failed to return right module, expected: %s, returned: %s\n",
+               exp_name, mod_name);
+        throw_exc(env, "check #B5: failed to return expected module for java/lang package");
+        return FAILED;
+    }
+
+    // Non-existing package: "bad/package/name"
+    err = get_module(env, loader, "bad/package/name", &module, &mod_name);
+    if (err != JVMTI_ERROR_NONE) {
+        throw_exc(env, "check #B6: failed to return JVMTI_ERROR_NONE for bad package");
+        return FAILED;
+    }
+    if (module != NULL || mod_name != NULL) {
+        throw_exc(env, "check #B7: failed to return NULL-module for bad package");
+        return FAILED;
+    }
+    return PASSED;
+}
+
+JNIEXPORT jint JNICALL
+Java_MyPackage_GetNamedModuleTest_check(JNIEnv *env, jclass cls) {
+    jobject loader = NULL;
+
+    if (jvmti == NULL) {
+        throw_exc(env, "JVMTI client was not properly loaded!\n");
+        return FAILED;
+    }
+
+    get_all_modules(env);
+
+    printf("\n*** Check for bad ClassLoader ***\n\n");
+    result = check_bad_loader(env, (jobject)cls);
+    if (result != PASSED) {
+        throw_exc(env, "check #L1: failed to return JVMTI_ERROR_ILLEGAL_ARGUMENT for bad loader");
+        return result;
+    }
+
+    loader = get_class_loader(cls);
+    if (loader == NULL) {
+        throw_exc(env, "check #L2: failed to return non-NULL loader for valid test class");
+        return FAILED;
+    }
+
+    printf("\n*** Checks for System ClassLoader ***\n\n");
+    result = check_system_loader(env, loader);
+    if (result != PASSED) {
+        return result;
+    }
+
+    printf("\n*** Checks for Bootstrap ClassLoader ***\n\n");
+    result = check_bootstrap_loader(env, NULL);
+
+    return result;
+}
+
+#ifdef __cplusplus
+}
+#endif