/*
 * Copyright (c) 2005, 2019, 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 com.sun.tools.javac.file;

import java.io.File;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.lang.module.Configuration;
import java.lang.module.ModuleFinder;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitOption;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.InvalidPathException;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.ProviderNotFoundException;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.spi.FileSystemProvider;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Objects;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import javax.lang.model.SourceVersion;
import javax.tools.FileObject;
import javax.tools.JavaFileManager;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;

import com.sun.tools.javac.file.RelativePath.RelativeDirectory;
import com.sun.tools.javac.file.RelativePath.RelativeFile;
import com.sun.tools.javac.main.Option;
import com.sun.tools.javac.resources.CompilerProperties.Errors;
import com.sun.tools.javac.util.Assert;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.Context.Factory;
import com.sun.tools.javac.util.DefinedBy;
import com.sun.tools.javac.util.DefinedBy.Api;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.ListBuffer;

import static java.nio.file.FileVisitOption.FOLLOW_LINKS;

import static javax.tools.StandardLocation.*;

This class provides access to the source, class and other files
used by the compiler and related tools.
This is NOT part of any supported API.
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.
/**
 * This class provides access to the source, class and other files
 * used by the compiler and related tools.
 *
 * <p><b>This is NOT part of any supported API.
 * 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>
 */
public class JavacFileManager extends BaseFileManager implements StandardJavaFileManager {

    public static char[] toArray(CharBuffer buffer) {
        if (buffer.hasArray())
            return buffer.compact().flip().array();
        else
            return buffer.toString().toCharArray();
    }

    private FSInfo fsInfo;

    private static final Set<JavaFileObject.Kind> SOURCE_OR_CLASS =
        Set.of(JavaFileObject.Kind.SOURCE, JavaFileObject.Kind.CLASS);

    protected boolean symbolFileEnabled;

    private PathFactory pathFactory = Paths::get;

    protected enum SortFiles implements Comparator<Path> {
        FORWARD {
            @Override
            public int compare(Path f1, Path f2) {
                return f1.getFileName().compareTo(f2.getFileName());
            }
        },
        REVERSE {
            @Override
            public int compare(Path f1, Path f2) {
                return -f1.getFileName().compareTo(f2.getFileName());
            }
        }
    }

    protected SortFiles sortFiles;

    
We use a two-layered map instead of a map with a complex key because we don't want to reindex
the values for every Location+RelativeDirectory pair. Once the PathsAndContainers are needed
for a single Location, we should know all valid RelativeDirectory mappings. Because the
indexing is costly for very large classpaths, this can result in a significant savings.
/**
     * We use a two-layered map instead of a map with a complex key because we don't want to reindex
     * the values for every Location+RelativeDirectory pair. Once the PathsAndContainers are needed
     * for a single Location, we should know all valid RelativeDirectory mappings. Because the
     * indexing is costly for very large classpaths, this can result in a significant savings.
     */
    private Map<Location, Map<RelativeDirectory, java.util.List<PathAndContainer>>>
        pathsAndContainersByLocationAndRelativeDirectory = new HashMap<>();

    
Containers that have no indexing by RelativeDirectory, keyed by Location. /** Containers that have no indexing by {@link RelativeDirectory}, keyed by {@link Location}. */
    private Map<Location, java.util.List<PathAndContainer>> nonIndexingContainersByLocation =
        new HashMap<>();

    
Register a Context.Factory to create a JavacFileManager.
/**
     * Register a Context.Factory to create a JavacFileManager.
     */
    public static void preRegister(Context context) {
        context.put(JavaFileManager.class,
                (Factory<JavaFileManager>)c -> new JavacFileManager(c, true, null));
    }

    
Create a JavacFileManager using a given context, optionally registering
it as the JavaFileManager for that context.
/**
     * Create a JavacFileManager using a given context, optionally registering
     * it as the JavaFileManager for that context.
     */
    public JavacFileManager(Context context, boolean register, Charset charset) {
        super(charset);
        if (register)
            context.put(JavaFileManager.class, this);
        setContext(context);
    }

    
Set the context for JavacFileManager.
/**
     * Set the context for JavacFileManager.
     */
    @Override
    public void setContext(Context context) {
        super.setContext(context);

        fsInfo = FSInfo.instance(context);

        symbolFileEnabled = !options.isSet("ignore.symbol.file");

        String sf = options.get("sortFiles");
        if (sf != null) {
            sortFiles = (sf.equals("reverse") ? SortFiles.REVERSE : SortFiles.FORWARD);
        }
    }

    @Override @DefinedBy(DefinedBy.Api.COMPILER)
    public void setPathFactory(PathFactory f) {
        pathFactory = Objects.requireNonNull(f);
        locations.setPathFactory(f);
    }

    private Path getPath(String first, String... more) {
        return pathFactory.getPath(first, more);
    }

    
Set whether or not to use ct.sym as an alternate to rt.jar.
/**
     * Set whether or not to use ct.sym as an alternate to rt.jar.
     */
    public void setSymbolFileEnabled(boolean b) {
        symbolFileEnabled = b;
    }

    public boolean isSymbolFileEnabled() {
        return symbolFileEnabled;
    }

    // used by tests
    public JavaFileObject getJavaFileObject(String name) {
        return getJavaFileObjects(name).iterator().next();
    }

    // used by tests
    public JavaFileObject getJavaFileObject(Path file) {
        return getJavaFileObjects(file).iterator().next();
    }

    public JavaFileObject getFileForOutput(String classname,
                                           JavaFileObject.Kind kind,
                                           JavaFileObject sibling)
        throws IOException
    {
        return getJavaFileForOutput(CLASS_OUTPUT, classname, kind, sibling);
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<? extends JavaFileObject> getJavaFileObjectsFromStrings(Iterable<String> names) {
        ListBuffer<Path> paths = new ListBuffer<>();
        for (String name : names)
            paths.append(getPath(nullCheck(name)));
        return getJavaFileObjectsFromPaths(paths.toList());
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<? extends JavaFileObject> getJavaFileObjects(String... names) {
        return getJavaFileObjectsFromStrings(Arrays.asList(nullCheck(names)));
    }

    private static boolean isValidName(String name) {
        // Arguably, isValidName should reject keywords (such as in SourceVersion.isName() ),
        // but the set of keywords depends on the source level, and we don't want
        // impls of JavaFileManager to have to be dependent on the source level.
        // Therefore we simply check that the argument is a sequence of identifiers
        // separated by ".".
        for (String s : name.split("\\.", -1)) {
            if (!SourceVersion.isIdentifier(s))
                return false;
        }
        return true;
    }

    private static void validateClassName(String className) {
        if (!isValidName(className))
            throw new IllegalArgumentException("Invalid class name: " + className);
    }

    private static void validatePackageName(String packageName) {
        if (packageName.length() > 0 && !isValidName(packageName))
            throw new IllegalArgumentException("Invalid packageName name: " + packageName);
    }

    public static void testName(String name,
                                boolean isValidPackageName,
                                boolean isValidClassName)
    {
        try {
            validatePackageName(name);
            if (!isValidPackageName)
                throw new AssertionError("Invalid package name accepted: " + name);
            printAscii("Valid package name: \"%s\"", name);
        } catch (IllegalArgumentException e) {
            if (isValidPackageName)
                throw new AssertionError("Valid package name rejected: " + name);
            printAscii("Invalid package name: \"%s\"", name);
        }
        try {
            validateClassName(name);
            if (!isValidClassName)
                throw new AssertionError("Invalid class name accepted: " + name);
            printAscii("Valid class name: \"%s\"", name);
        } catch (IllegalArgumentException e) {
            if (isValidClassName)
                throw new AssertionError("Valid class name rejected: " + name);
            printAscii("Invalid class name: \"%s\"", name);
        }
    }

    private static void printAscii(String format, Object... args) {
        String message;
        try {
            final String ascii = "US-ASCII";
            message = new String(String.format(null, format, args).getBytes(ascii), ascii);
        } catch (java.io.UnsupportedEncodingException ex) {
            throw new AssertionError(ex);
        }
        System.out.println(message);
    }

    private final Map<Path, Container> containers = new HashMap<>();

    synchronized Container getContainer(Path path) throws IOException {
        Container fs = containers.get(path);

        if (fs != null) {
            return fs;
        }

        if (fsInfo.isFile(path) && path.equals(Locations.thisSystemModules)) {
            containers.put(path, fs = new JRTImageContainer());
            return fs;
        }

        Path realPath = fsInfo.getCanonicalFile(path);

        fs = containers.get(realPath);

        if (fs != null) {
            containers.put(path, fs);
            return fs;
        }

        BasicFileAttributes attr = null;

        try {
            attr = Files.readAttributes(realPath, BasicFileAttributes.class);
        } catch (IOException ex) {
            //non-existing
            fs = MISSING_CONTAINER;
        }

        if (attr != null) {
            if (attr.isDirectory()) {
                fs = new DirectoryContainer(realPath);
            } else {
                try {
                    fs = new ArchiveContainer(path);
                } catch (ProviderNotFoundException | SecurityException ex) {
                    throw new IOException(ex);
                }
            }
        }

        containers.put(realPath, fs);
        containers.put(path, fs);

        return fs;
    }

    private interface Container {
        
Insert all files in subdirectory subdirectory of container which
match fileKinds into resultList
/**
         * Insert all files in subdirectory subdirectory of container which
         * match fileKinds into resultList
         */
        public abstract void list(Path userPath,
                                  RelativeDirectory subdirectory,
                                  Set<JavaFileObject.Kind> fileKinds,
                                  boolean recurse,
                                  ListBuffer<JavaFileObject> resultList) throws IOException;
        public abstract JavaFileObject getFileObject(Path userPath, RelativeFile name) throws IOException;
        public abstract void close() throws IOException;
        public abstract boolean maintainsDirectoryIndex();

        
The directories this container indexes if maintainsDirectoryIndex(), otherwise an empty iterable. /**
         * The directories this container indexes if {@link #maintainsDirectoryIndex()}, otherwise
         * an empty iterable.
         */
        public abstract Iterable<RelativeDirectory> indexedDirectories();
    }

    private static final Container MISSING_CONTAINER =  new Container() {
        @Override
        public void list(Path userPath,
                         RelativeDirectory subdirectory,
                         Set<JavaFileObject.Kind> fileKinds,
                         boolean recurse,
                         ListBuffer<JavaFileObject> resultList) throws IOException {
        }
        @Override
        public JavaFileObject getFileObject(Path userPath, RelativeFile name) throws IOException {
            return null;
        }
        @Override
        public void close() throws IOException {}
        @Override
        public boolean maintainsDirectoryIndex() {
            return false;
        }
        @Override
        public Iterable<RelativeDirectory> indexedDirectories() {
            return List.nil();
        }
    };

    private final class JRTImageContainer implements Container {

        
Insert all files in a subdirectory of the platform image
which match fileKinds into resultList.
/**
         * Insert all files in a subdirectory of the platform image
         * which match fileKinds into resultList.
         */
        @Override
        public void list(Path userPath,
                         RelativeDirectory subdirectory,
                         Set<JavaFileObject.Kind> fileKinds,
                         boolean recurse,
                         ListBuffer<JavaFileObject> resultList) throws IOException {
            try {
                JRTIndex.Entry e = getJRTIndex().getEntry(subdirectory);
                if (symbolFileEnabled && e.ctSym.hidden)
                    return;
                for (Path file: e.files.values()) {
                    if (fileKinds.contains(getKind(file))) {
                        JavaFileObject fe
                                = PathFileObject.forJRTPath(JavacFileManager.this, file);
                        resultList.append(fe);
                    }
                }

                if (recurse) {
                    for (RelativeDirectory rd: e.subdirs) {
                        list(userPath, rd, fileKinds, recurse, resultList);
                    }
                }
            } catch (IOException ex) {
                ex.printStackTrace(System.err);
                log.error(Errors.ErrorReadingFile(userPath, getMessage(ex)));
            }
        }

        @Override
        public JavaFileObject getFileObject(Path userPath, RelativeFile name) throws IOException {
            JRTIndex.Entry e = getJRTIndex().getEntry(name.dirname());
            if (symbolFileEnabled && e.ctSym.hidden)
                return null;
            Path p = e.files.get(name.basename());
            if (p != null) {
                return PathFileObject.forJRTPath(JavacFileManager.this, p);
            } else {
                return null;
            }
        }

        @Override
        public void close() throws IOException {
        }

        @Override
        public boolean maintainsDirectoryIndex() {
            return false;
        }

        @Override
        public Iterable<RelativeDirectory> indexedDirectories() {
            return List.nil();
        }
    }

    private synchronized JRTIndex getJRTIndex() {
        if (jrtIndex == null)
            jrtIndex = JRTIndex.getSharedInstance();
        return jrtIndex;
    }

    private JRTIndex jrtIndex;

    private final class DirectoryContainer implements Container {
        private final Path directory;

        public DirectoryContainer(Path directory) {
            this.directory = directory;
        }

        
Insert all files in subdirectory subdirectory of directory userPath
which match fileKinds into resultList
/**
         * Insert all files in subdirectory subdirectory of directory userPath
         * which match fileKinds into resultList
         */
        @Override
        public void list(Path userPath,
                         RelativeDirectory subdirectory,
                         Set<JavaFileObject.Kind> fileKinds,
                         boolean recurse,
                         ListBuffer<JavaFileObject> resultList) throws IOException {
            Path d;
            try {
                d = subdirectory.resolveAgainst(userPath);
            } catch (InvalidPathException ignore) {
                return ;
            }

            if (!Files.exists(d)) {
               return;
            }

            if (!caseMapCheck(d, subdirectory)) {
                return;
            }

            java.util.List<Path> files;
            try (Stream<Path> s = Files.list(d)) {
                files = (sortFiles == null ? s : s.sorted(sortFiles)).collect(Collectors.toList());
            } catch (IOException ignore) {
                return;
            }

            for (Path f: files) {
                String fname = f.getFileName().toString();
                if (fname.endsWith("/"))
                    fname = fname.substring(0, fname.length() - 1);
                if (Files.isDirectory(f)) {
                    if (recurse && SourceVersion.isIdentifier(fname)) {
                        list(userPath,
                             new RelativeDirectory(subdirectory, fname),
                             fileKinds,
                             recurse,
                             resultList);
                    }
                } else {
                    if (isValidFile(fname, fileKinds)) {
                        try {
                            RelativeFile file = new RelativeFile(subdirectory, fname);
                            JavaFileObject fe = PathFileObject.forDirectoryPath(JavacFileManager.this,
                                    file.resolveAgainst(directory), userPath, file);
                            resultList.append(fe);
                        } catch (InvalidPathException e) {
                            throw new IOException("error accessing directory " + directory + e);
                        }
                    }
                }
            }
        }

        @Override
        public JavaFileObject getFileObject(Path userPath, RelativeFile name) throws IOException {
            try {
                Path f = name.resolveAgainst(userPath);
                if (Files.exists(f))
                    return PathFileObject.forSimplePath(JavacFileManager.this,
                            fsInfo.getCanonicalFile(f), f);
            } catch (InvalidPathException ignore) {
            }
            return null;
        }

        @Override
        public void close() throws IOException {
        }

        @Override
        public boolean maintainsDirectoryIndex() {
            return false;
        }

        @Override
        public Iterable<RelativeDirectory> indexedDirectories() {
            return List.nil();
        }
    }

    private static final Set<FileVisitOption> NO_FILE_VISIT_OPTIONS = Set.of();
    private static final Set<FileVisitOption> FOLLOW_LINKS_OPTIONS = Set.of(FOLLOW_LINKS);

    private final class ArchiveContainer implements Container {
        private final Path archivePath;
        private final FileSystem fileSystem;
        private final Map<RelativeDirectory, Path> packages;

        public ArchiveContainer(Path archivePath) throws IOException, ProviderNotFoundException, SecurityException {
            this.archivePath = archivePath;
            if (multiReleaseValue != null && archivePath.toString().endsWith(".jar")) {
                Map<String,String> env = Collections.singletonMap("multi-release", multiReleaseValue);
                FileSystemProvider jarFSProvider = fsInfo.getJarFSProvider();
                Assert.checkNonNull(jarFSProvider, "should have been caught before!");
                this.fileSystem = jarFSProvider.newFileSystem(archivePath, env);
            } else {
                this.fileSystem = FileSystems.newFileSystem(archivePath, (ClassLoader)null);
            }
            packages = new HashMap<>();
            for (Path root : fileSystem.getRootDirectories()) {
                Files.walkFileTree(root, NO_FILE_VISIT_OPTIONS, Integer.MAX_VALUE,
                        new SimpleFileVisitor<Path>() {
                            @Override
                            public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
                                if (isValid(dir.getFileName())) {
                                    packages.put(new RelativeDirectory(root.relativize(dir).toString()), dir);
                                    return FileVisitResult.CONTINUE;
                                } else {
                                    return FileVisitResult.SKIP_SUBTREE;
                                }
                            }
                        });
            }
        }

        
Insert all files in subdirectory subdirectory of this archive
which match fileKinds into resultList
/**
         * Insert all files in subdirectory subdirectory of this archive
         * which match fileKinds into resultList
         */
        @Override
        public void list(Path userPath,
                         RelativeDirectory subdirectory,
                         Set<JavaFileObject.Kind> fileKinds,
                         boolean recurse,
                         ListBuffer<JavaFileObject> resultList) throws IOException {
            Path resolvedSubdirectory = packages.get(subdirectory);

            if (resolvedSubdirectory == null)
                return ;

            int maxDepth = (recurse ? Integer.MAX_VALUE : 1);
            Files.walkFileTree(resolvedSubdirectory, FOLLOW_LINKS_OPTIONS, maxDepth,
                    new SimpleFileVisitor<Path>() {
                        @Override
                        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
                            if (isValid(dir.getFileName())) {
                                return FileVisitResult.CONTINUE;
                            } else {
                                return FileVisitResult.SKIP_SUBTREE;
                            }
                        }

                        @Override
                        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
                            if (attrs.isRegularFile() && fileKinds.contains(getKind(file.getFileName().toString()))) {
                                JavaFileObject fe = PathFileObject.forJarPath(
                                        JavacFileManager.this, file, archivePath);
                                resultList.append(fe);
                            }
                            return FileVisitResult.CONTINUE;
                        }
                    });

        }

        private boolean isValid(Path fileName) {
            if (fileName == null) {
                return true;
            } else {
                String name = fileName.toString();
                if (name.endsWith("/")) {
                    name = name.substring(0, name.length() - 1);
                }
                return SourceVersion.isIdentifier(name);
            }
        }

        @Override
        public JavaFileObject getFileObject(Path userPath, RelativeFile name) throws IOException {
            RelativeDirectory root = name.dirname();
            Path packagepath = packages.get(root);
            if (packagepath != null) {
                Path relpath = packagepath.resolve(name.basename());
                if (Files.exists(relpath)) {
                    return PathFileObject.forJarPath(JavacFileManager.this, relpath, userPath);
                }
            }
            return null;
        }

        @Override
        public void close() throws IOException {
            fileSystem.close();
        }

        @Override
        public boolean maintainsDirectoryIndex() {
            return true;
        }

        @Override
        public Iterable<RelativeDirectory> indexedDirectories() {
            return packages.keySet();
        }
    }

    
container is a directory, a zip file, or a non-existent path.
/**
     * container is a directory, a zip file, or a non-existent path.
     */
    private boolean isValidFile(String s, Set<JavaFileObject.Kind> fileKinds) {
        JavaFileObject.Kind kind = getKind(s);
        return fileKinds.contains(kind);
    }

    private static final boolean fileSystemIsCaseSensitive =
        File.separatorChar == '/';

    
Hack to make Windows case sensitive. Test whether given path
 ends in a string of characters with the same case as given name.
 Ignore file separators in both path and name.
/** Hack to make Windows case sensitive. Test whether given path
     *  ends in a string of characters with the same case as given name.
     *  Ignore file separators in both path and name.
     */
    private boolean caseMapCheck(Path f, RelativePath name) {
        if (fileSystemIsCaseSensitive) return true;
        // Note that toRealPath() returns the case-sensitive
        // spelled file name.
        String path;
        char sep;
        try {
            path = f.toRealPath(LinkOption.NOFOLLOW_LINKS).toString();
            sep = f.getFileSystem().getSeparator().charAt(0);
        } catch (IOException ex) {
            return false;
        }
        char[] pcs = path.toCharArray();
        char[] ncs = name.path.toCharArray();
        int i = pcs.length - 1;
        int j = ncs.length - 1;
        while (i >= 0 && j >= 0) {
            while (i >= 0 && pcs[i] == sep) i--;
            while (j >= 0 && ncs[j] == '/') j--;
            if (i >= 0 && j >= 0) {
                if (pcs[i] != ncs[j]) return false;
                i--;
                j--;
            }
        }
        return j < 0;
    }

    
Flush any output resources.
/** Flush any output resources.
     */
    @Override @DefinedBy(Api.COMPILER)
    public void flush() {
        contentCache.clear();
        pathsAndContainersByLocationAndRelativeDirectory.clear();
        nonIndexingContainersByLocation.clear();
    }

    
Close the JavaFileManager, releasing resources.
/**
     * Close the JavaFileManager, releasing resources.
     */
    @Override @DefinedBy(Api.COMPILER)
    public void close() throws IOException {
        if (deferredCloseTimeout > 0) {
            deferredClose();
            return;
        }

        locations.close();
        for (Container container: containers.values()) {
            container.close();
        }
        containers.clear();
        pathsAndContainersByLocationAndRelativeDirectory.clear();
        nonIndexingContainersByLocation.clear();
        contentCache.clear();
    }

    @Override @DefinedBy(Api.COMPILER)
    public ClassLoader getClassLoader(Location location) {
        checkNotModuleOrientedLocation(location);
        Iterable<? extends File> path = getLocation(location);
        if (path == null)
            return null;
        ListBuffer<URL> lb = new ListBuffer<>();
        for (File f: path) {
            try {
                lb.append(f.toURI().toURL());
            } catch (MalformedURLException e) {
                throw new AssertionError(e);
            }
        }

        return getClassLoader(lb.toArray(new URL[lb.size()]));
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<JavaFileObject> list(Location location,
                                         String packageName,
                                         Set<JavaFileObject.Kind> kinds,
                                         boolean recurse)
        throws IOException
    {
        checkNotModuleOrientedLocation(location);
        // validatePackageName(packageName);
        nullCheck(packageName);
        nullCheck(kinds);

        RelativeDirectory subdirectory = RelativeDirectory.forPackage(packageName);
        ListBuffer<JavaFileObject> results = new ListBuffer<>();

        for (PathAndContainer pathAndContainer : pathsAndContainers(location, subdirectory)) {
            Path directory = pathAndContainer.path;
            Container container = pathAndContainer.container;
            container.list(directory, subdirectory, kinds, recurse, results);
        }

        return results.toList();
    }

    @Override @DefinedBy(Api.COMPILER)
    public String inferBinaryName(Location location, JavaFileObject file) {
        checkNotModuleOrientedLocation(location);
        Objects.requireNonNull(file);
        // Need to match the path semantics of list(location, ...)
        Iterable<? extends Path> path = getLocationAsPaths(location);
        if (path == null) {
            return null;
        }

        if (file instanceof PathFileObject) {
            return ((PathFileObject) file).inferBinaryName(path);
        } else
            throw new IllegalArgumentException(file.getClass().getName());
    }

    @Override @DefinedBy(Api.COMPILER)
    public boolean isSameFile(FileObject a, FileObject b) {
        nullCheck(a);
        nullCheck(b);
        if (a instanceof PathFileObject && b instanceof PathFileObject)
            return ((PathFileObject) a).isSameFile((PathFileObject) b);
        return a.equals(b);
    }

    @Override @DefinedBy(Api.COMPILER)
    public boolean hasLocation(Location location) {
        nullCheck(location);
        return locations.hasLocation(location);
    }

    protected boolean hasExplicitLocation(Location location) {
        nullCheck(location);
        return locations.hasExplicitLocation(location);
    }

    @Override @DefinedBy(Api.COMPILER)
    public JavaFileObject getJavaFileForInput(Location location,
                                              String className,
                                              JavaFileObject.Kind kind)
        throws IOException
    {
        checkNotModuleOrientedLocation(location);
        // validateClassName(className);
        nullCheck(className);
        nullCheck(kind);
        if (!SOURCE_OR_CLASS.contains(kind))
            throw new IllegalArgumentException("Invalid kind: " + kind);
        return getFileForInput(location, RelativeFile.forClass(className, kind));
    }

    @Override @DefinedBy(Api.COMPILER)
    public FileObject getFileForInput(Location location,
                                      String packageName,
                                      String relativeName)
        throws IOException
    {
        checkNotModuleOrientedLocation(location);
        // validatePackageName(packageName);
        nullCheck(packageName);
        if (!isRelativeUri(relativeName))
            throw new IllegalArgumentException("Invalid relative name: " + relativeName);
        RelativeFile name = packageName.length() == 0
            ? new RelativeFile(relativeName)
            : new RelativeFile(RelativeDirectory.forPackage(packageName), relativeName);
        return getFileForInput(location, name);
    }

    private JavaFileObject getFileForInput(Location location, RelativeFile name) throws IOException {
        Iterable<? extends Path> path = getLocationAsPaths(location);
        if (path == null)
            return null;

        for (Path file: path) {
            JavaFileObject fo = getContainer(file).getFileObject(file, name);

            if (fo != null) {
                return fo;
            }
        }
        return null;
    }

    @Override @DefinedBy(Api.COMPILER)
    public JavaFileObject getJavaFileForOutput(Location location,
                                               String className,
                                               JavaFileObject.Kind kind,
                                               FileObject sibling)
        throws IOException
    {
        checkOutputLocation(location);
        // validateClassName(className);
        nullCheck(className);
        nullCheck(kind);
        if (!SOURCE_OR_CLASS.contains(kind))
            throw new IllegalArgumentException("Invalid kind: " + kind);
        return getFileForOutput(location, RelativeFile.forClass(className, kind), sibling);
    }

    @Override @DefinedBy(Api.COMPILER)
    public FileObject getFileForOutput(Location location,
                                       String packageName,
                                       String relativeName,
                                       FileObject sibling)
        throws IOException
    {
        checkOutputLocation(location);
        // validatePackageName(packageName);
        nullCheck(packageName);
        if (!isRelativeUri(relativeName))
            throw new IllegalArgumentException("Invalid relative name: " + relativeName);
        RelativeFile name = packageName.length() == 0
            ? new RelativeFile(relativeName)
            : new RelativeFile(RelativeDirectory.forPackage(packageName), relativeName);
        return getFileForOutput(location, name, sibling);
    }

    private JavaFileObject getFileForOutput(Location location,
                                            RelativeFile fileName,
                                            FileObject sibling)
        throws IOException
    {
        Path dir;
        if (location == CLASS_OUTPUT) {
            if (getClassOutDir() != null) {
                dir = getClassOutDir();
            } else {
                String baseName = fileName.basename();
                if (sibling != null && sibling instanceof PathFileObject) {
                    return ((PathFileObject) sibling).getSibling(baseName);
                } else {
                    Path p = getPath(baseName);
                    Path real = fsInfo.getCanonicalFile(p);
                    return PathFileObject.forSimplePath(this, real, p);
                }
            }
        } else if (location == SOURCE_OUTPUT) {
            dir = (getSourceOutDir() != null ? getSourceOutDir() : getClassOutDir());
        } else {
            Iterable<? extends Path> path = locations.getLocation(location);
            dir = null;
            for (Path f: path) {
                dir = f;
                break;
            }
        }

        try {
            if (dir == null) {
                dir = getPath(System.getProperty("user.dir"));
            }
            Path path = fileName.resolveAgainst(fsInfo.getCanonicalFile(dir));
            return PathFileObject.forDirectoryPath(this, path, dir, fileName);
        } catch (InvalidPathException e) {
            throw new IOException("bad filename " + fileName, e);
        }
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<? extends JavaFileObject> getJavaFileObjectsFromFiles(
        Iterable<? extends File> files)
    {
        ArrayList<PathFileObject> result;
        if (files instanceof Collection<?>)
            result = new ArrayList<>(((Collection<?>)files).size());
        else
            result = new ArrayList<>();
        for (File f: files) {
            Objects.requireNonNull(f);
            Path p = f.toPath();
            result.add(PathFileObject.forSimplePath(this,
                    fsInfo.getCanonicalFile(p), p));
        }
        return result;
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<? extends JavaFileObject> getJavaFileObjectsFromPaths(
        Collection<? extends Path> paths)
    {
        ArrayList<PathFileObject> result;
        if (paths instanceof Collection<?>)
            result = new ArrayList<>(((Collection<?>)paths).size());
        else
            result = new ArrayList<>();
        for (Path p: paths)
            result.add(PathFileObject.forSimplePath(this,
                    fsInfo.getCanonicalFile(p), p));
        return result;
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<? extends JavaFileObject> getJavaFileObjects(File... files) {
        return getJavaFileObjectsFromFiles(Arrays.asList(nullCheck(files)));
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<? extends JavaFileObject> getJavaFileObjects(Path... paths) {
        return getJavaFileObjectsFromPaths(Arrays.asList(nullCheck(paths)));
    }

    @Override @DefinedBy(Api.COMPILER)
    public void setLocation(Location location,
                            Iterable<? extends File> searchpath)
        throws IOException
    {
        nullCheck(location);
        locations.setLocation(location, asPaths(searchpath));
        clearCachesForLocation(location);
    }

    @Override @DefinedBy(Api.COMPILER)
    public void setLocationFromPaths(Location location,
                            Collection<? extends Path> searchpath)
        throws IOException
    {
        nullCheck(location);
        locations.setLocation(location, nullCheck(searchpath));
        clearCachesForLocation(location);
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<? extends File> getLocation(Location location) {
        nullCheck(location);
        return asFiles(locations.getLocation(location));
    }

    @Override @DefinedBy(Api.COMPILER)
    public Collection<? extends Path> getLocationAsPaths(Location location) {
        nullCheck(location);
        return locations.getLocation(location);
    }

    private java.util.List<PathAndContainer> pathsAndContainers(
            Location location, RelativeDirectory relativeDirectory) throws IOException {
        try {
            return pathsAndContainersByLocationAndRelativeDirectory.computeIfAbsent(
                    location, this::indexPathsAndContainersByRelativeDirectory)
                .computeIfAbsent(
                    relativeDirectory, d -> nonIndexingContainersByLocation.get(location));
        } catch (UncheckedIOException e) {
            throw e.getCause();
        }
    }

    private Map<RelativeDirectory, java.util.List<PathAndContainer>> indexPathsAndContainersByRelativeDirectory(
            Location location) {
        Map<RelativeDirectory, java.util.List<PathAndContainer>> result = new HashMap<>();
        java.util.List<PathAndContainer> allPathsAndContainers = pathsAndContainers(location);

        // First collect all of the containers that don't maintain their own index on
        // RelativeDirectory. These need to always be included for all mappings
        java.util.List<PathAndContainer> nonIndexingContainers = new ArrayList<>();
        for (PathAndContainer pathAndContainer : allPathsAndContainers) {
            if (!pathAndContainer.container.maintainsDirectoryIndex()) {
                nonIndexingContainers.add(pathAndContainer);
            }
        }

        // Next, use the container that do maintain their own RelativeDirectory index to create a
        // single master index.
        for (PathAndContainer pathAndContainer : allPathsAndContainers) {
            Container container = pathAndContainer.container;
            if (container.maintainsDirectoryIndex()) {
                for (RelativeDirectory directory : container.indexedDirectories()) {
                    result.computeIfAbsent(directory, d -> new ArrayList<>(nonIndexingContainers))
                          .add(pathAndContainer);
                }
            }
        }
        nonIndexingContainersByLocation.put(location, nonIndexingContainers);

        // Sorting preserves the search order used in the uncached Location path, which has
        // maintains consistency with the classpath order
        result.values().forEach(pathAndContainerList -> Collections.sort(pathAndContainerList));

        return result;
    }

    
For each path of the location, compute the corresponding Container. /**
     * For each {@linkplain #getLocationAsPaths(Location) path of the location}, compute the
     * corresponding {@link Container}.
     */
    private java.util.List<PathAndContainer> pathsAndContainers(Location location) {
        Collection<? extends Path> paths = getLocationAsPaths(location);
        if (paths == null) {
            return List.nil();
        }
        java.util.List<PathAndContainer> pathsAndContainers =
            new ArrayList<>(paths.size());
        for (Path path : paths) {
            Container container;
            try {
                container = getContainer(path);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
            pathsAndContainers.add(new PathAndContainer(path, container, pathsAndContainers.size()));
        }
        return pathsAndContainers;
    }

    private static class PathAndContainer implements Comparable<PathAndContainer> {
        private final Path path;
        private final Container container;
        private final int index;

        PathAndContainer(Path path, Container container, int index) {
            this.path = path;
            this.container = container;
            this.index = index;
        }

        @Override
        public int compareTo(PathAndContainer other) {
            return index - other.index;
        }

        @Override
        public boolean equals(Object o) {
          if (o == null || !(o instanceof PathAndContainer)) {
            return false;
          }
          PathAndContainer that = (PathAndContainer) o;
          return path.equals(that.path)
              && container.equals(that.container)
              && index == this.index;
        }

        @Override
        public int hashCode() {
          return Objects.hash(path, container, index);
        }
    }

    @Override @DefinedBy(Api.COMPILER)
    public boolean contains(Location location, FileObject fo) throws IOException {
        nullCheck(location);
        nullCheck(fo);
        Path p = asPath(fo);
        return locations.contains(location, p);
    }

    private Path getClassOutDir() {
        return locations.getOutputLocation(CLASS_OUTPUT);
    }

    private Path getSourceOutDir() {
        return locations.getOutputLocation(SOURCE_OUTPUT);
    }

    @Override @DefinedBy(Api.COMPILER)
    public Location getLocationForModule(Location location, String moduleName) throws IOException {
        checkModuleOrientedOrOutputLocation(location);
        nullCheck(moduleName);
        if (location == SOURCE_OUTPUT && getSourceOutDir() == null)
            location = CLASS_OUTPUT;
        return locations.getLocationForModule(location, moduleName);
    }

    @Override @DefinedBy(Api.COMPILER)
    public <S> ServiceLoader<S> getServiceLoader(Location location, Class<S> service) throws IOException {
        nullCheck(location);
        nullCheck(service);
        getClass().getModule().addUses(service);
        if (location.isModuleOrientedLocation()) {
            Collection<Path> paths = locations.getLocation(location);
            ModuleFinder finder = ModuleFinder.of(paths.toArray(new Path[paths.size()]));
            ModuleLayer bootLayer = ModuleLayer.boot();
            Configuration cf = bootLayer.configuration().resolveAndBind(ModuleFinder.of(), finder, Collections.emptySet());
            ModuleLayer layer = bootLayer.defineModulesWithOneLoader(cf, ClassLoader.getSystemClassLoader());
            return ServiceLoader.load(layer, service);
        } else {
            return ServiceLoader.load(service, getClassLoader(location));
        }
    }

    @Override @DefinedBy(Api.COMPILER)
    public Location getLocationForModule(Location location, JavaFileObject fo) throws IOException {
        checkModuleOrientedOrOutputLocation(location);
        if (!(fo instanceof PathFileObject))
            return null;
        Path p = Locations.normalize(((PathFileObject) fo).path);
            // need to find p in location
        return locations.getLocationForModule(location, p);
    }

    @Override @DefinedBy(Api.COMPILER)
    public void setLocationForModule(Location location, String moduleName, Collection<? extends Path> paths)
            throws IOException {
        nullCheck(location);
        checkModuleOrientedOrOutputLocation(location);
        locations.setLocationForModule(location, nullCheck(moduleName), nullCheck(paths));
        clearCachesForLocation(location);
    }

    @Override @DefinedBy(Api.COMPILER)
    public String inferModuleName(Location location) {
        checkNotModuleOrientedLocation(location);
        return locations.inferModuleName(location);
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<Set<Location>> listLocationsForModules(Location location) throws IOException {
        checkModuleOrientedOrOutputLocation(location);
        return locations.listLocationsForModules(location);
    }

    @Override @DefinedBy(Api.COMPILER)
    public Path asPath(FileObject file) {
        if (file instanceof PathFileObject) {
            return ((PathFileObject) file).path;
        } else
            throw new IllegalArgumentException(file.getName());
    }

    
Enforces the specification of a "relative" name as used in 
getFileForInput. This method must follow the rules defined in that method, do not make any changes without consulting the specification. /**
     * Enforces the specification of a "relative" name as used in
     * {@linkplain #getFileForInput(Location,String,String)
     * getFileForInput}.  This method must follow the rules defined in
     * that method, do not make any changes without consulting the
     * specification.
     */
    protected static boolean isRelativeUri(URI uri) {
        if (uri.isAbsolute())
            return false;
        String path = uri.normalize().getPath();
        if (path.length() == 0 /* isEmpty() is mustang API */)
            return false;
        if (!path.equals(uri.getPath())) // implicitly checks for embedded . and ..
            return false;
        if (path.startsWith("/") || path.startsWith("./") || path.startsWith("../"))
            return false;
        return true;
    }

    // Convenience method
    protected static boolean isRelativeUri(String u) {
        try {
            return isRelativeUri(new URI(u));
        } catch (URISyntaxException e) {
            return false;
        }
    }

    
Converts a relative file name to a relative URI.  This is
different from File.toURI as this method does not canonicalize
the file before creating the URI.  Furthermore, no schema is
used.
Params:
file – a relative file name
Throws:
IllegalArgumentException – if the file name is not relative according to the definition given in JavaFileManager.getFileForInput
Returns:
a relative URI/**
     * Converts a relative file name to a relative URI.  This is
     * different from File.toURI as this method does not canonicalize
     * the file before creating the URI.  Furthermore, no schema is
     * used.
     * @param file a relative file name
     * @return a relative URI
     * @throws IllegalArgumentException if the file name is not
     * relative according to the definition given in {@link
     * javax.tools.JavaFileManager#getFileForInput}
     */
    public static String getRelativeName(File file) {
        if (!file.isAbsolute()) {
            String result = file.getPath().replace(File.separatorChar, '/');
            if (isRelativeUri(result))
                return result;
        }
        throw new IllegalArgumentException("Invalid relative path: " + file);
    }

    
Get a detail message from an IOException.
Most, but not all, instances of IOException provide a non-null result
for getLocalizedMessage().  But some instances return null: in these
cases, fall back to getMessage(), and if even that is null, return the
name of the exception itself.
Params:
e – an IOException
Returns:
a string to include in a compiler diagnostic/**
     * Get a detail message from an IOException.
     * Most, but not all, instances of IOException provide a non-null result
     * for getLocalizedMessage().  But some instances return null: in these
     * cases, fall back to getMessage(), and if even that is null, return the
     * name of the exception itself.
     * @param e an IOException
     * @return a string to include in a compiler diagnostic
     */
    public static String getMessage(IOException e) {
        String s = e.getLocalizedMessage();
        if (s != null)
            return s;
        s = e.getMessage();
        if (s != null)
            return s;
        return e.toString();
    }

    private void checkOutputLocation(Location location) {
        Objects.requireNonNull(location);
        if (!location.isOutputLocation())
            throw new IllegalArgumentException("location is not an output location: " + location.getName());
    }

    private void checkModuleOrientedOrOutputLocation(Location location) {
        Objects.requireNonNull(location);
        if (!location.isModuleOrientedLocation() && !location.isOutputLocation())
            throw new IllegalArgumentException(
                    "location is not an output location or a module-oriented location: "
                            + location.getName());
    }

    private void checkNotModuleOrientedLocation(Location location) {
        Objects.requireNonNull(location);
        if (location.isModuleOrientedLocation())
            throw new IllegalArgumentException("location is module-oriented: " + location.getName());
    }

    /* Converters between files and paths.
     * These are temporary until we can update the StandardJavaFileManager API.
     */

    private static Iterable<Path> asPaths(final Iterable<? extends File> files) {
        if (files == null)
            return null;

        return () -> new Iterator<Path>() {
            Iterator<? extends File> iter = files.iterator();

            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public Path next() {
                return iter.next().toPath();
            }
        };
    }

    private static Iterable<File> asFiles(final Iterable<? extends Path> paths) {
        if (paths == null)
            return null;

        return () -> new Iterator<File>() {
            Iterator<? extends Path> iter = paths.iterator();

            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public File next() {
                try {
                    return iter.next().toFile();
                } catch (UnsupportedOperationException e) {
                    throw new IllegalStateException(e);
                }
            }
        };
    }

    @Override
    public boolean handleOption(Option option, String value) {
        if (javacFileManagerOptions.contains(option)) {
            pathsAndContainersByLocationAndRelativeDirectory.clear();
            nonIndexingContainersByLocation.clear();
        }
        return super.handleOption(option, value);
    }

    private void clearCachesForLocation(Location location) {
        nullCheck(location);
        pathsAndContainersByLocationAndRelativeDirectory.remove(location);
        nonIndexingContainersByLocation.remove(location);
    }
}