/*
 * Copyright (c) 2007, 2020, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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 sun.launcher;

/*
 *
 *  <p><b>This is NOT part of any API supported by Sun Microsystems.
 *  If you write code that depends on this, you do so at your own
 *  risk.  This code and its internal interfaces are subject to change
 *  or deletion without notice.</b>
 *
 */

/**
 * A utility package for the java(1), javaw(1) launchers.
 * The following are helper methods that the native launcher uses
 * to perform checks etc. using JNI, see src/share/bin/java.c
 */
import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;
import java.lang.module.Configuration;
import java.lang.module.ModuleDescriptor;
import java.lang.module.ModuleDescriptor.Exports;
import java.lang.module.ModuleDescriptor.Opens;
import java.lang.module.ModuleDescriptor.Provides;
import java.lang.module.ModuleDescriptor.Requires;
import java.lang.module.ModuleFinder;
import java.lang.module.ModuleReference;
import java.lang.module.ResolvedModule;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.net.URI;
import java.nio.charset.Charset;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.text.MessageFormat;
import java.text.Normalizer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Locale.Category;
import java.util.Optional;
import java.util.Properties;
import java.util.ResourceBundle;
import java.util.Set;
import java.util.TreeSet;
import java.util.jar.Attributes;
import java.util.jar.JarFile;
import java.util.jar.Manifest;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import jdk.internal.misc.VM;
import jdk.internal.module.ModuleBootstrap;
import jdk.internal.module.Modules;
import jdk.internal.platform.Container;
import jdk.internal.platform.Metrics;


public final class LauncherHelper {

    // No instantiation
    private LauncherHelper() {}

    // used to identify JavaFX applications
    private static final String JAVAFX_APPLICATION_MARKER =
            "JavaFX-Application-Class";
    private static final String JAVAFX_APPLICATION_CLASS_NAME =
            "javafx.application.Application";
    private static final String JAVAFX_FXHELPER_CLASS_NAME_SUFFIX =
            "sun.launcher.LauncherHelper$FXHelper";
    private static final String LAUNCHER_AGENT_CLASS = "Launcher-Agent-Class";
    private static final String MAIN_CLASS = "Main-Class";
    private static final String ADD_EXPORTS = "Add-Exports";
    private static final String ADD_OPENS = "Add-Opens";

    private static StringBuilder outBuf = new StringBuilder();

    private static final String INDENT = "    ";
    private static final String VM_SETTINGS     = "VM settings:";
    private static final String PROP_SETTINGS   = "Property settings:";
    private static final String LOCALE_SETTINGS = "Locale settings:";

    // sync with java.c and jdk.internal.misc.VM
    private static final String diagprop = "sun.java.launcher.diag";
    static final boolean trace = VM.getSavedProperty(diagprop) != null;

    private static final String defaultBundleName =
            "sun.launcher.resources.launcher";

    private static class ResourceBundleHolder {
        private static final ResourceBundle RB =
                ResourceBundle.getBundle(defaultBundleName);
    }
    private static PrintStream ostream;
    private static Class<?> appClass; // application class, for GUI/reporting purposes

    /*
     * A method called by the launcher to print out the standard settings,
     * by default -XshowSettings is equivalent to -XshowSettings:all,
     * Specific information may be gotten by using suboptions with possible
     * values vm, properties and locale.
     *
     * printToStderr: choose between stdout and stderr
     *
     * optionFlag: specifies which options to print default is all other
     *    possible values are vm, properties, locale.
     *
     * initialHeapSize: in bytes, as set by the launcher, a zero-value indicates
     *    this code should determine this value, using a suitable method or
     *    the line could be omitted.
     *
     * maxHeapSize: in bytes, as set by the launcher, a zero-value indicates
     *    this code should determine this value, using a suitable method.
     *
     * stackSize: in bytes, as set by the launcher, a zero-value indicates
     *    this code determine this value, using a suitable method or omit the
     *    line entirely.
     */
    @SuppressWarnings("fallthrough")
    static void showSettings(boolean printToStderr, String optionFlag,
            long initialHeapSize, long maxHeapSize, long stackSize) {

        initOutput(printToStderr);
        String opts[] = optionFlag.split(":");
        String optStr = (opts.length > 1 && opts[1] != null)
                ? opts[1].trim()
                : "all";
        switch (optStr) {
            case "vm":
                printVmSettings(initialHeapSize, maxHeapSize, stackSize);
                break;
            case "properties":
                printProperties();
                break;
            case "locale":
                printLocale();
                break;
            case "system":
                if (System.getProperty("os.name").contains("Linux")) {
                    printSystemMetrics();
                    break;
                }
            default:
                printVmSettings(initialHeapSize, maxHeapSize, stackSize);
                printProperties();
                printLocale();
                if (System.getProperty("os.name").contains("Linux")) {
                    printSystemMetrics();
                }
                break;
        }
    }

    /*
     * prints the main vm settings subopt/section
     */
    private static void printVmSettings(
            long initialHeapSize, long maxHeapSize,
            long stackSize) {

        ostream.println(VM_SETTINGS);
        if (stackSize != 0L) {
            ostream.println(INDENT + "Stack Size: " +
                    SizePrefix.scaleValue(stackSize));
        }
        if (initialHeapSize != 0L) {
             ostream.println(INDENT + "Min. Heap Size: " +
                    SizePrefix.scaleValue(initialHeapSize));
        }
        if (maxHeapSize != 0L) {
            ostream.println(INDENT + "Max. Heap Size: " +
                    SizePrefix.scaleValue(maxHeapSize));
        } else {
            ostream.println(INDENT + "Max. Heap Size (Estimated): "
                    + SizePrefix.scaleValue(Runtime.getRuntime().maxMemory()));
        }
        ostream.println(INDENT + "Using VM: "
                + System.getProperty("java.vm.name"));
        ostream.println();
    }

    /*
     * prints the properties subopt/section
     */
    private static void printProperties() {
        Properties p = System.getProperties();
        ostream.println(PROP_SETTINGS);
        List<String> sortedPropertyKeys = new ArrayList<>();
        sortedPropertyKeys.addAll(p.stringPropertyNames());
        Collections.sort(sortedPropertyKeys);
        for (String x : sortedPropertyKeys) {
            printPropertyValue(x, p.getProperty(x));
        }
        ostream.println();
    }

    private static boolean isPath(String key) {
        return key.endsWith(".dirs") || key.endsWith(".path");
    }

    private static void printPropertyValue(String key, String value) {
        ostream.print(INDENT + key + " = ");
        if (key.equals("line.separator")) {
            for (byte b : value.getBytes()) {
                switch (b) {
                    case 0xd:
                        ostream.print("\\r ");
                        break;
                    case 0xa:
                        ostream.print("\\n ");
                        break;
                    default:
                        // print any bizzare line separators in hex, but really
                        // shouldn't happen.
                        ostream.printf("0x%02X", b & 0xff);
                        break;
                }
            }
            ostream.println();
            return;
        }
        if (!isPath(key)) {
            ostream.println(value);
            return;
        }
        String[] values = value.split(System.getProperty("path.separator"));
        boolean first = true;
        for (String s : values) {
            if (first) { // first line treated specially
                ostream.println(s);
                first = false;
            } else { // following lines prefix with indents
                ostream.println(INDENT + INDENT + s);
            }
        }
    }

    /*
     * prints the locale subopt/section
     */
    private static void printLocale() {
        Locale locale = Locale.getDefault();
        ostream.println(LOCALE_SETTINGS);
        ostream.println(INDENT + "default locale = " +
                locale.getDisplayName());
        ostream.println(INDENT + "default display locale = " +
                Locale.getDefault(Category.DISPLAY).getDisplayName());
        ostream.println(INDENT + "default format locale = " +
                Locale.getDefault(Category.FORMAT).getDisplayName());
        printLocales();
        ostream.println();
    }

    private static void printLocales() {
        Locale[] tlocales = Locale.getAvailableLocales();
        final int len = tlocales == null ? 0 : tlocales.length;
        if (len < 1 ) {
            return;
        }
        // Locale does not implement Comparable so we convert it to String
        // and sort it for pretty printing.
        Set<String> sortedSet = new TreeSet<>();
        for (Locale l : tlocales) {
            sortedSet.add(l.toString());
        }

        ostream.print(INDENT + "available locales = ");
        Iterator<String> iter = sortedSet.iterator();
        final int last = len - 1;
        for (int i = 0 ; iter.hasNext() ; i++) {
            String s = iter.next();
            ostream.print(s);
            if (i != last) {
                ostream.print(", ");
            }
            // print columns of 8
            if ((i + 1) % 8 == 0) {
                ostream.println();
                ostream.print(INDENT + INDENT);
            }
        }
    }

    public static void printSystemMetrics() {
        Metrics c = Container.metrics();

        ostream.println("Operating System Metrics:");

        if (c == null) {
            ostream.println(INDENT + "No metrics available for this platform");
            return;
        }

        final long longRetvalNotSupported = -2;

        ostream.println(INDENT + "Provider: " + c.getProvider());
        ostream.println(INDENT + "Effective CPU Count: " + c.getEffectiveCpuCount());
        ostream.println(formatCpuVal(c.getCpuPeriod(), INDENT + "CPU Period: ", longRetvalNotSupported));
        ostream.println(formatCpuVal(c.getCpuQuota(), INDENT + "CPU Quota: ", longRetvalNotSupported));
        ostream.println(formatCpuVal(c.getCpuShares(), INDENT + "CPU Shares: ", longRetvalNotSupported));

        int cpus[] = c.getCpuSetCpus();
        if (cpus != null) {
            ostream.println(INDENT + "List of Processors, "
                    + cpus.length + " total: ");

            ostream.print(INDENT);
            for (int i = 0; i < cpus.length; i++) {
                ostream.print(cpus[i] + " ");
            }
            if (cpus.length > 0) {
                ostream.println("");
            }
        } else {
            ostream.println(INDENT + "List of Processors: N/A");
        }

        cpus = c.getEffectiveCpuSetCpus();
        if (cpus != null) {
            ostream.println(INDENT + "List of Effective Processors, "
                    + cpus.length + " total: ");

            ostream.print(INDENT);
            for (int i = 0; i < cpus.length; i++) {
                ostream.print(cpus[i] + " ");
            }
            if (cpus.length > 0) {
                ostream.println("");
            }
        } else {
            ostream.println(INDENT + "List of Effective Processors: N/A");
        }

        int mems[] = c.getCpuSetMems();
        if (mems != null) {
            ostream.println(INDENT + "List of Memory Nodes, "
                    + mems.length + " total: ");

            ostream.print(INDENT);
            for (int i = 0; i < mems.length; i++) {
                ostream.print(mems[i] + " ");
            }
            if (mems.length > 0) {
                ostream.println("");
            }
        } else {
            ostream.println(INDENT + "List of Memory Nodes: N/A");
        }

        mems = c.getEffectiveCpuSetMems();
        if (mems != null) {
            ostream.println(INDENT + "List of Available Memory Nodes, "
                    + mems.length + " total: ");

            ostream.print(INDENT);
            for (int i = 0; i < mems.length; i++) {
                ostream.print(mems[i] + " ");
            }
            if (mems.length > 0) {
                ostream.println("");
            }
        } else {
            ostream.println(INDENT + "List of Available Memory Nodes: N/A");
        }

        long limit = c.getMemoryLimit();
        ostream.println(formatLimitString(limit, INDENT + "Memory Limit: ", longRetvalNotSupported));

        limit = c.getMemorySoftLimit();
        ostream.println(formatLimitString(limit, INDENT + "Memory Soft Limit: ", longRetvalNotSupported));

        limit = c.getMemoryAndSwapLimit();
        ostream.println(formatLimitString(limit, INDENT + "Memory & Swap Limit: ", longRetvalNotSupported));

        ostream.println("");
    }

    private static String formatLimitString(long limit, String prefix, long unavailable) {
        if (limit >= 0) {
            return prefix + SizePrefix.scaleValue(limit);
        } else if (limit == unavailable) {
            return prefix + "N/A";
        } else {
            return prefix + "Unlimited";
        }
    }

    private static String formatCpuVal(long cpuVal, String prefix, long unavailable) {
        if (cpuVal >= 0) {
            return prefix + cpuVal + "us";
        } else if (cpuVal == unavailable) {
            return prefix + "N/A";
        } else {
            return prefix + cpuVal;
        }
    }

    private enum SizePrefix {

        KILO(1024, "K"),
        MEGA(1024 * 1024, "M"),
        GIGA(1024 * 1024 * 1024, "G"),
        TERA(1024L * 1024L * 1024L * 1024L, "T");
        long size;
        String abbrev;

        SizePrefix(long size, String abbrev) {
            this.size = size;
            this.abbrev = abbrev;
        }

        private static String scale(long v, SizePrefix prefix) {
            return BigDecimal.valueOf(v).divide(BigDecimal.valueOf(prefix.size),
                    2, RoundingMode.HALF_EVEN).toPlainString() + prefix.abbrev;
        }
        /*
         * scale the incoming values to a human readable form, represented as
         * K, M, G and T, see java.c parse_size for the scaled values and
         * suffixes. The lowest possible scaled value is Kilo.
         */
        static String scaleValue(long v) {
            if (v < MEGA.size) {
                return scale(v, KILO);
            } else if (v < GIGA.size) {
                return scale(v, MEGA);
            } else if (v < TERA.size) {
                return scale(v, GIGA);
            } else {
                return scale(v, TERA);
            }
        }
    }

    
A private helper method to get a localized message and also
apply any arguments that we might pass.
/**
     * A private helper method to get a localized message and also
     * apply any arguments that we might pass.
     */
    private static String getLocalizedMessage(String key, Object... args) {
        String msg = ResourceBundleHolder.RB.getString(key);
        return (args != null) ? MessageFormat.format(msg, args) : msg;
    }

    
The java -help message is split into 3 parts, an invariant, followed
by a set of platform dependent variant messages, finally an invariant
set of lines.
This method initializes the help message for the first time, and also
assembles the invariant header part of the message.
/**
     * The java -help message is split into 3 parts, an invariant, followed
     * by a set of platform dependent variant messages, finally an invariant
     * set of lines.
     * This method initializes the help message for the first time, and also
     * assembles the invariant header part of the message.
     */
    static void initHelpMessage(String progname) {
        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.header",
                (progname == null) ? "java" : progname ));
    }

    
Appends the vm selection messages to the header, already created.
initHelpSystem must already be called.
/**
     * Appends the vm selection messages to the header, already created.
     * initHelpSystem must already be called.
     */
    static void appendVmSelectMessage(String vm1, String vm2) {
        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.vmselect",
                vm1, vm2));
    }

    
Appends the vm synoym message to the header, already created.
initHelpSystem must be called before using this method.
/**
     * Appends the vm synoym message to the header, already created.
     * initHelpSystem must be called before using this method.
     */
    static void appendVmSynonymMessage(String vm1, String vm2) {
        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.hotspot",
                vm1, vm2));
    }

    
Appends the last invariant part to the previously created messages,
and finishes up the printing to the desired output stream.
initHelpSystem must be called before using this method.
/**
     * Appends the last invariant part to the previously created messages,
     * and finishes up the printing to the desired output stream.
     * initHelpSystem must be called before using this method.
     */
    static void printHelpMessage(boolean printToStderr) {
        initOutput(printToStderr);
        outBuf = outBuf.append(getLocalizedMessage("java.launcher.opt.footer",
                File.pathSeparator));
        ostream.println(outBuf.toString());
    }

    
Prints the Xusage text to the desired output stream.
/**
     * Prints the Xusage text to the desired output stream.
     */
    static void printXUsageMessage(boolean printToStderr) {
        initOutput(printToStderr);
        ostream.println(getLocalizedMessage("java.launcher.X.usage",
                File.pathSeparator));
        if (System.getProperty("os.name").contains("OS X")) {
            ostream.println(getLocalizedMessage("java.launcher.X.macosx.usage",
                        File.pathSeparator));
        }
    }

    static void initOutput(boolean printToStderr) {
        ostream =  (printToStderr) ? System.err : System.out;
    }

    static void initOutput(PrintStream ps) {
        ostream = ps;
    }

    static String getMainClassFromJar(String jarname) {
        String mainValue;
        try (JarFile jarFile = new JarFile(jarname)) {
            Manifest manifest = jarFile.getManifest();
            if (manifest == null) {
                abort(null, "java.launcher.jar.error2", jarname);
            }
            Attributes mainAttrs = manifest.getMainAttributes();
            if (mainAttrs == null) {
                abort(null, "java.launcher.jar.error3", jarname);
            }

            // Main-Class
            mainValue = mainAttrs.getValue(MAIN_CLASS);
            if (mainValue == null) {
                abort(null, "java.launcher.jar.error3", jarname);
            }

            // Launcher-Agent-Class (only check for this when Main-Class present)
            String agentClass = mainAttrs.getValue(LAUNCHER_AGENT_CLASS);
            if (agentClass != null) {
                ModuleLayer.boot().findModule("java.instrument").ifPresent(m -> {
                    try {
                        String cn = "sun.instrument.InstrumentationImpl";
                        Class<?> clazz = Class.forName(cn, false, null);
                        Method loadAgent = clazz.getMethod("loadAgent", String.class);
                        loadAgent.invoke(null, jarname);
                    } catch (Throwable e) {
                        if (e instanceof InvocationTargetException) e = e.getCause();
                        abort(e, "java.launcher.jar.error4", jarname);
                    }
                });
            }

            // Add-Exports and Add-Opens
            String exports = mainAttrs.getValue(ADD_EXPORTS);
            if (exports != null) {
                addExportsOrOpens(exports, false);
            }
            String opens = mainAttrs.getValue(ADD_OPENS);
            if (opens != null) {
                addExportsOrOpens(opens, true);
            }

            /*
             * Hand off to FXHelper if it detects a JavaFX application
             * This must be done after ensuring a Main-Class entry
             * exists to enforce compliance with the jar specification
             */
            if (mainAttrs.containsKey(
                    new Attributes.Name(JAVAFX_APPLICATION_MARKER))) {
                FXHelper.setFXLaunchParameters(jarname, LM_JAR);
                return FXHelper.class.getName();
            }

            return mainValue.trim();
        } catch (IOException ioe) {
            abort(ioe, "java.launcher.jar.error1", jarname);
        }
        return null;
    }

    
Process the Add-Exports or Add-Opens value. The value is <module>/<package> ( <module>/<package>)*. /**
     * Process the Add-Exports or Add-Opens value. The value is
     * {@code <module>/<package> ( <module>/<package>)*}.
     */
    static void addExportsOrOpens(String value, boolean open) {
        for (String moduleAndPackage : value.split(" ")) {
            String[] s = moduleAndPackage.trim().split("/");
            if (s.length == 2) {
                String mn = s[0];
                String pn = s[1];
                ModuleLayer.boot()
                    .findModule(mn)
                    .filter(m -> m.getDescriptor().packages().contains(pn))
                    .ifPresent(m -> {
                        if (open) {
                            Modules.addOpensToAllUnnamed(m, pn);
                        } else {
                            Modules.addExportsToAllUnnamed(m, pn);
                        }
                    });
            }
        }
    }

    // From src/share/bin/java.c:
    //   enum LaunchMode { LM_UNKNOWN = 0, LM_CLASS, LM_JAR, LM_MODULE, LM_SOURCE }

    private static final int LM_UNKNOWN = 0;
    private static final int LM_CLASS   = 1;
    private static final int LM_JAR     = 2;
    private static final int LM_MODULE  = 3;
    private static final int LM_SOURCE  = 4;

    static void abort(Throwable t, String msgKey, Object... args) {
        if (msgKey != null) {
            ostream.println(getLocalizedMessage(msgKey, args));
        }
        if (trace) {
            if (t != null) {
                t.printStackTrace();
            } else {
                Thread.dumpStack();
            }
        }
        System.exit(1);
    }

    
This method:
1. Loads the main class from the module or class path
2. Checks the public static void main method.
3. If the main class extends FX Application then call on FXHelper to
perform the launch.
Params:
printToStderr – if set, all output will be routed to stderr
mode – LaunchMode as determined by the arguments passed on the
            command line
what – the module name[/class], JAR file, or the main class
            depending on the mode
Returns:
the application's main class/**
     * This method:
     * 1. Loads the main class from the module or class path
     * 2. Checks the public static void main method.
     * 3. If the main class extends FX Application then call on FXHelper to
     * perform the launch.
     *
     * @param printToStderr if set, all output will be routed to stderr
     * @param mode LaunchMode as determined by the arguments passed on the
     *             command line
     * @param what the module name[/class], JAR file, or the main class
     *             depending on the mode
     *
     * @return the application's main class
     */
    @SuppressWarnings("fallthrough")
    public static Class<?> checkAndLoadMain(boolean printToStderr,
                                            int mode,
                                            String what) {
        initOutput(printToStderr);

        Class<?> mainClass = null;
        switch (mode) {
            case LM_MODULE: case LM_SOURCE:
                mainClass = loadModuleMainClass(what);
                break;
            default:
                mainClass = loadMainClass(mode, what);
                break;
        }

        // record the real main class for UI purposes
        // neither method above can return null, they will abort()
        appClass = mainClass;

        /*
         * Check if FXHelper can launch it using the FX launcher. In an FX app,
         * the main class may or may not have a main method, so do this before
         * validating the main class.
         */
        if (JAVAFX_FXHELPER_CLASS_NAME_SUFFIX.equals(mainClass.getName()) ||
            doesExtendFXApplication(mainClass)) {
            // Will abort() if there are problems with FX runtime
            FXHelper.setFXLaunchParameters(what, mode);
            mainClass = FXHelper.class;
        }

        validateMainClass(mainClass);
        return mainClass;
    }

    
Returns the main class for a module. The query is either a module name
or module-name/main-class. For the former then the module's main class
is obtained from the module descriptor (MainClass attribute).
/**
     * Returns the main class for a module. The query is either a module name
     * or module-name/main-class. For the former then the module's main class
     * is obtained from the module descriptor (MainClass attribute).
     */
    private static Class<?> loadModuleMainClass(String what) {
        int i = what.indexOf('/');
        String mainModule;
        String mainClass;
        if (i == -1) {
            mainModule = what;
            mainClass = null;
        } else {
            mainModule = what.substring(0, i);
            mainClass = what.substring(i+1);
        }

        // main module is in the boot layer
        ModuleLayer layer = ModuleLayer.boot();
        Optional<Module> om = layer.findModule(mainModule);
        if (!om.isPresent()) {
            // should not happen
            throw new InternalError("Module " + mainModule + " not in boot Layer");
        }
        Module m = om.get();

        // get main class
        if (mainClass == null) {
            Optional<String> omc = m.getDescriptor().mainClass();
            if (!omc.isPresent()) {
                abort(null, "java.launcher.module.error1", mainModule);
            }
            mainClass = omc.get();
        }

        // load the class from the module
        Class<?> c = null;
        try {
            c = Class.forName(m, mainClass);
            if (c == null && System.getProperty("os.name", "").contains("OS X")
                    && Normalizer.isNormalized(mainClass, Normalizer.Form.NFD)) {

                String cn = Normalizer.normalize(mainClass, Normalizer.Form.NFC);
                c = Class.forName(m, cn);
            }
        } catch (LinkageError le) {
            abort(null, "java.launcher.module.error3", mainClass, m.getName(),
                    le.getClass().getName() + ": " + le.getLocalizedMessage());
        }
        if (c == null) {
            abort(null, "java.launcher.module.error2", mainClass, mainModule);
        }

        System.setProperty("jdk.module.main.class", c.getName());
        return c;
    }

    
Loads the main class from the class path (LM_CLASS or LM_JAR).
/**
     * Loads the main class from the class path (LM_CLASS or LM_JAR).
     */
    private static Class<?> loadMainClass(int mode, String what) {
        // get the class name
        String cn;
        switch (mode) {
            case LM_CLASS:
                cn = what;
                break;
            case LM_JAR:
                cn = getMainClassFromJar(what);
                break;
            default:
                // should never happen
                throw new InternalError("" + mode + ": Unknown launch mode");
        }

        // load the main class
        cn = cn.replace('/', '.');
        Class<?> mainClass = null;
        ClassLoader scl = ClassLoader.getSystemClassLoader();
        try {
            try {
                mainClass = Class.forName(cn, false, scl);
            } catch (NoClassDefFoundError | ClassNotFoundException cnfe) {
                if (System.getProperty("os.name", "").contains("OS X")
                        && Normalizer.isNormalized(cn, Normalizer.Form.NFD)) {
                    try {
                        // On Mac OS X since all names with diacritical marks are
                        // given as decomposed it is possible that main class name
                        // comes incorrectly from the command line and we have
                        // to re-compose it
                        String ncn = Normalizer.normalize(cn, Normalizer.Form.NFC);
                        mainClass = Class.forName(ncn, false, scl);
                    } catch (NoClassDefFoundError | ClassNotFoundException cnfe1) {
                        abort(cnfe1, "java.launcher.cls.error1", cn,
                                cnfe1.getClass().getCanonicalName(), cnfe1.getMessage());
                    }
                } else {
                    abort(cnfe, "java.launcher.cls.error1", cn,
                            cnfe.getClass().getCanonicalName(), cnfe.getMessage());
                }
            }
        } catch (LinkageError le) {
            abort(le, "java.launcher.cls.error6", cn,
                    le.getClass().getName() + ": " + le.getLocalizedMessage());
        }
        return mainClass;
    }

    /*
     * Accessor method called by the launcher after getting the main class via
     * checkAndLoadMain(). The "application class" is the class that is finally
     * executed to start the application and in this case is used to report
     * the correct application name, typically for UI purposes.
     */
    public static Class<?> getApplicationClass() {
        return appClass;
    }

    /*
     * Check if the given class is a JavaFX Application class. This is done
     * in a way that does not cause the Application class to load or throw
     * ClassNotFoundException if the JavaFX runtime is not available.
     */
    private static boolean doesExtendFXApplication(Class<?> mainClass) {
        for (Class<?> sc = mainClass.getSuperclass(); sc != null;
                sc = sc.getSuperclass()) {
            if (sc.getName().equals(JAVAFX_APPLICATION_CLASS_NAME)) {
                return true;
            }
        }
        return false;
    }

    // Check the existence and signature of main and abort if incorrect
    static void validateMainClass(Class<?> mainClass) {
        Method mainMethod = null;
        try {
            mainMethod = mainClass.getMethod("main", String[].class);
        } catch (NoSuchMethodException nsme) {
            // invalid main or not FX application, abort with an error
            abort(null, "java.launcher.cls.error4", mainClass.getName(),
                  JAVAFX_APPLICATION_CLASS_NAME);
        } catch (Throwable e) {
            if (mainClass.getModule().isNamed()) {
                abort(e, "java.launcher.module.error5",
                      mainClass.getName(), mainClass.getModule().getName(),
                      e.getClass().getName(), e.getLocalizedMessage());
            } else {
                abort(e, "java.launcher.cls.error7", mainClass.getName(),
                      e.getClass().getName(), e.getLocalizedMessage());
            }
        }

        /*
         * getMethod (above) will choose the correct method, based
         * on its name and parameter type, however, we still have to
         * ensure that the method is static and returns a void.
         */
        int mod = mainMethod.getModifiers();
        if (!Modifier.isStatic(mod)) {
            abort(null, "java.launcher.cls.error2", "static",
                  mainMethod.getDeclaringClass().getName());
        }
        if (mainMethod.getReturnType() != java.lang.Void.TYPE) {
            abort(null, "java.launcher.cls.error3",
                  mainMethod.getDeclaringClass().getName());
        }
    }

    private static final String encprop = "sun.jnu.encoding";
    private static String encoding = null;
    private static boolean isCharsetSupported = false;

    /*
     * converts a c or a byte array to a platform specific string,
     * previously implemented as a native method in the launcher.
     */
    static String makePlatformString(boolean printToStderr, byte[] inArray) {
        initOutput(printToStderr);
        if (encoding == null) {
            encoding = System.getProperty(encprop);
            isCharsetSupported = Charset.isSupported(encoding);
        }
        try {
            String out = isCharsetSupported
                    ? new String(inArray, encoding)
                    : new String(inArray);
            return out;
        } catch (UnsupportedEncodingException uee) {
            abort(uee, null);
        }
        return null; // keep the compiler happy
    }

    static String[] expandArgs(String[] argArray) {
        List<StdArg> aList = new ArrayList<>();
        for (String x : argArray) {
            aList.add(new StdArg(x));
        }
        return expandArgs(aList);
    }

    static String[] expandArgs(List<StdArg> argList) {
        ArrayList<String> out = new ArrayList<>();
        if (trace) {
            System.err.println("Incoming arguments:");
        }
        for (StdArg a : argList) {
            if (trace) {
                System.err.println(a);
            }
            if (a.needsExpansion) {
                File x = new File(a.arg);
                File parent = x.getParentFile();
                String glob = x.getName();
                if (parent == null) {
                    parent = new File(".");
                }
                try (DirectoryStream<Path> dstream =
                        Files.newDirectoryStream(parent.toPath(), glob)) {
                    int entries = 0;
                    for (Path p : dstream) {
                        out.add(p.normalize().toString());
                        entries++;
                    }
                    if (entries == 0) {
                        out.add(a.arg);
                    }
                } catch (Exception e) {
                    out.add(a.arg);
                    if (trace) {
                        System.err.println("Warning: passing argument as-is " + a);
                        System.err.print(e);
                    }
                }
            } else {
                out.add(a.arg);
            }
        }
        String[] oarray = new String[out.size()];
        out.toArray(oarray);

        if (trace) {
            System.err.println("Expanded arguments:");
            for (String x : oarray) {
                System.err.println(x);
            }
        }
        return oarray;
    }

    /* duplicate of the native StdArg struct */
    private static class StdArg {
        final String arg;
        final boolean needsExpansion;
        StdArg(String arg, boolean expand) {
            this.arg = arg;
            this.needsExpansion = expand;
        }
        // protocol: first char indicates whether expansion is required
        // 'T' = true ; needs expansion
        // 'F' = false; needs no expansion
        StdArg(String in) {
            this.arg = in.substring(1);
            needsExpansion = in.charAt(0) == 'T';
        }
        public String toString() {
            return "StdArg{" + "arg=" + arg + ", needsExpansion=" + needsExpansion + '}';
        }
    }

    static final class FXHelper {

        private static final String JAVAFX_GRAPHICS_MODULE_NAME =
                "javafx.graphics";

        private static final String JAVAFX_LAUNCHER_CLASS_NAME =
                "com.sun.javafx.application.LauncherImpl";

        /*
         * The launch method used to invoke the JavaFX launcher. These must
         * match the strings used in the launchApplication method.
         *
         * Command line                 JavaFX-App-Class  Launch mode  FX Launch mode
         * java -cp fxapp.jar FXClass   N/A               LM_CLASS     "LM_CLASS"
         * java -cp somedir FXClass     N/A               LM_CLASS     "LM_CLASS"
         * java -jar fxapp.jar          Present           LM_JAR       "LM_JAR"
         * java -jar fxapp.jar          Not Present       LM_JAR       "LM_JAR"
         * java -m module/class [1]     N/A               LM_MODULE    "LM_MODULE"
         * java -m module               N/A               LM_MODULE    "LM_MODULE"
         *
         * [1] - JavaFX-Application-Class is ignored when modular args are used, even
         * if present in a modular jar
         */
        private static final String JAVAFX_LAUNCH_MODE_CLASS = "LM_CLASS";
        private static final String JAVAFX_LAUNCH_MODE_JAR = "LM_JAR";
        private static final String JAVAFX_LAUNCH_MODE_MODULE = "LM_MODULE";

        /*
         * FX application launcher and launch method, so we can launch
         * applications with no main method.
         */
        private static String fxLaunchName = null;
        private static String fxLaunchMode = null;

        private static Class<?> fxLauncherClass    = null;
        private static Method   fxLauncherMethod   = null;

        /*
         * Set the launch params according to what was passed to LauncherHelper
         * so we can use the same launch mode for FX. Abort if there is any
         * issue with loading the FX runtime or with the launcher method.
         */
        private static void setFXLaunchParameters(String what, int mode) {

            // find the module with the FX launcher
            Optional<Module> om = ModuleLayer.boot().findModule(JAVAFX_GRAPHICS_MODULE_NAME);
            if (!om.isPresent()) {
                abort(null, "java.launcher.cls.error5");
            }

            // load the FX launcher class
            fxLauncherClass = Class.forName(om.get(), JAVAFX_LAUNCHER_CLASS_NAME);
            if (fxLauncherClass == null) {
                abort(null, "java.launcher.cls.error5");
            }

            try {
                /*
                 * signature must be:
                 * public static void launchApplication(String launchName,
                 *     String launchMode, String[] args);
                 */
                fxLauncherMethod = fxLauncherClass.getMethod("launchApplication",
                        String.class, String.class, String[].class);

                // verify launcher signature as we do when validating the main method
                int mod = fxLauncherMethod.getModifiers();
                if (!Modifier.isStatic(mod)) {
                    abort(null, "java.launcher.javafx.error1");
                }
                if (fxLauncherMethod.getReturnType() != java.lang.Void.TYPE) {
                    abort(null, "java.launcher.javafx.error1");
                }
            } catch (NoSuchMethodException ex) {
                abort(ex, "java.launcher.cls.error5", ex);
            }

            fxLaunchName = what;
            switch (mode) {
                case LM_CLASS:
                    fxLaunchMode = JAVAFX_LAUNCH_MODE_CLASS;
                    break;
                case LM_JAR:
                    fxLaunchMode = JAVAFX_LAUNCH_MODE_JAR;
                    break;
                case LM_MODULE:
                    fxLaunchMode = JAVAFX_LAUNCH_MODE_MODULE;
                    break;
                default:
                    // should not have gotten this far...
                    throw new InternalError(mode + ": Unknown launch mode");
            }
        }

        public static void main(String... args) throws Exception {
            if (fxLauncherMethod == null
                    || fxLaunchMode == null
                    || fxLaunchName == null) {
                throw new RuntimeException("Invalid JavaFX launch parameters");
            }
            // launch appClass via fxLauncherMethod
            fxLauncherMethod.invoke(null,
                    new Object[] {fxLaunchName, fxLaunchMode, args});
        }
    }

    
Called by the launcher to list the observable modules.
/**
     * Called by the launcher to list the observable modules.
     */
    static void listModules() {
        initOutput(System.out);

        ModuleBootstrap.limitedFinder().findAll().stream()
            .sorted(new JrtFirstComparator())
            .forEach(LauncherHelper::showModule);
    }

    
Called by the launcher to show the resolved modules
/**
     * Called by the launcher to show the resolved modules
     */
    static void showResolvedModules() {
        initOutput(System.out);

        ModuleLayer bootLayer = ModuleLayer.boot();
        Configuration cf = bootLayer.configuration();

        cf.modules().stream()
            .map(ResolvedModule::reference)
            .sorted(new JrtFirstComparator())
            .forEach(LauncherHelper::showModule);
    }

    
Called by the launcher to describe a module
/**
     * Called by the launcher to describe a module
     */
    static void describeModule(String moduleName) {
        initOutput(System.out);

        ModuleFinder finder = ModuleBootstrap.limitedFinder();
        ModuleReference mref = finder.find(moduleName).orElse(null);
        if (mref == null) {
            abort(null, "java.launcher.module.error4", moduleName);
        }
        ModuleDescriptor md = mref.descriptor();

        // one-line summary
        showModule(mref);

        // unqualified exports (sorted by package)
        md.exports().stream()
            .filter(e -> !e.isQualified())
            .sorted(Comparator.comparing(Exports::source))
            .map(e -> Stream.concat(Stream.of(e.source()),
                                    toStringStream(e.modifiers()))
                    .collect(Collectors.joining(" ")))
            .forEach(sourceAndMods -> ostream.format("exports %s%n", sourceAndMods));

        // dependences
        for (Requires r : md.requires()) {
            String nameAndMods = Stream.concat(Stream.of(r.name()),
                                               toStringStream(r.modifiers()))
                    .collect(Collectors.joining(" "));
            ostream.format("requires %s", nameAndMods);
            finder.find(r.name())
                .map(ModuleReference::descriptor)
                .filter(ModuleDescriptor::isAutomatic)
                .ifPresent(any -> ostream.print(" automatic"));
            ostream.println();
        }

        // service use and provides
        for (String s : md.uses()) {
            ostream.format("uses %s%n", s);
        }
        for (Provides ps : md.provides()) {
            String names = ps.providers().stream().collect(Collectors.joining(" "));
            ostream.format("provides %s with %s%n", ps.service(), names);

        }

        // qualified exports
        for (Exports e : md.exports()) {
            if (e.isQualified()) {
                String who = e.targets().stream().collect(Collectors.joining(" "));
                ostream.format("qualified exports %s to %s%n", e.source(), who);
            }
        }

        // open packages
        for (Opens opens: md.opens()) {
            if (opens.isQualified())
                ostream.print("qualified ");
            String sourceAndMods = Stream.concat(Stream.of(opens.source()),
                                                 toStringStream(opens.modifiers()))
                    .collect(Collectors.joining(" "));
            ostream.format("opens %s", sourceAndMods);
            if (opens.isQualified()) {
                String who = opens.targets().stream().collect(Collectors.joining(" "));
                ostream.format(" to %s", who);
            }
            ostream.println();
        }

        // non-exported/non-open packages
        Set<String> concealed = new TreeSet<>(md.packages());
        md.exports().stream().map(Exports::source).forEach(concealed::remove);
        md.opens().stream().map(Opens::source).forEach(concealed::remove);
        concealed.forEach(p -> ostream.format("contains %s%n", p));
    }

    
Prints a single line with the module name, version and modifiers
/**
     * Prints a single line with the module name, version and modifiers
     */
    private static void showModule(ModuleReference mref) {
        ModuleDescriptor md = mref.descriptor();
        ostream.print(md.toNameAndVersion());
        mref.location()
                .filter(uri -> !isJrt(uri))
                .ifPresent(uri -> ostream.format(" %s", uri));
        if (md.isOpen())
            ostream.print(" open");
        if (md.isAutomatic())
            ostream.print(" automatic");
        ostream.println();
    }

    
A ModuleReference comparator that considers modules in the run-time
image to be less than modules than not in the run-time image.
/**
     * A ModuleReference comparator that considers modules in the run-time
     * image to be less than modules than not in the run-time image.
     */
    private static class JrtFirstComparator implements Comparator<ModuleReference> {
        private final Comparator<ModuleReference> real;

        JrtFirstComparator() {
            this.real = Comparator.comparing(ModuleReference::descriptor);
        }

        @Override
        public int compare(ModuleReference a, ModuleReference b) {
            if (isJrt(a)) {
                return isJrt(b) ? real.compare(a, b) : -1;
            } else {
                return isJrt(b) ? 1 : real.compare(a, b);
            }
        }
    }

    private static <T> Stream<String> toStringStream(Set<T> s) {
        return s.stream().map(e -> e.toString().toLowerCase());
    }

    private static boolean isJrt(ModuleReference mref) {
        return isJrt(mref.location().orElse(null));
    }

    private static boolean isJrt(URI uri) {
        return (uri != null && uri.getScheme().equalsIgnoreCase("jrt"));
    }

}