MoreFiles.java
/*
* Copyright (C) 2013 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.io;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;
import static java.nio.file.LinkOption.NOFOLLOW_LINKS;
import static java.util.Objects.requireNonNull;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Optional;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableList;
import com.google.common.graph.SuccessorsFunction;
import com.google.common.graph.Traverser;
import com.google.j2objc.annotations.J2ObjCIncompatible;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.channels.Channels;
import java.nio.channels.SeekableByteChannel;
import java.nio.charset.Charset;
import java.nio.file.DirectoryIteratorException;
import java.nio.file.DirectoryStream;
import java.nio.file.FileAlreadyExistsException;
import java.nio.file.FileSystemException;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.NoSuchFileException;
import java.nio.file.NotDirectoryException;
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.SecureDirectoryStream;
import java.nio.file.StandardOpenOption;
import java.nio.file.attribute.BasicFileAttributeView;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.FileTime;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.stream.Stream;
import javax.annotation.CheckForNull;
/**
* Static utilities for use with {@link Path} instances, intended to complement {@link Files}.
*
* <p>Many methods provided by Guava's {@code Files} class for {@link java.io.File} instances are
* now available via the JDK's {@link java.nio.file.Files} class for {@code Path} - check the JDK's
* class if a sibling method from {@code Files} appears to be missing from this class.
*
* @since 21.0
* @author Colin Decker
*/
@Beta
@GwtIncompatible
@J2ObjCIncompatible // java.nio.file
@ElementTypesAreNonnullByDefault
public final class MoreFiles {
private MoreFiles() {}
/**
* Returns a view of the given {@code path} as a {@link ByteSource}.
*
* <p>Any {@linkplain OpenOption open options} provided are used when opening streams to the file
* and may affect the behavior of the returned source and the streams it provides. See {@link
* StandardOpenOption} for the standard options that may be provided. Providing no options is
* equivalent to providing the {@link StandardOpenOption#READ READ} option.
*/
public static ByteSource asByteSource(Path path, OpenOption... options) {
return new PathByteSource(path, options);
}
private static final class PathByteSource extends ByteSource {
private static final LinkOption[] FOLLOW_LINKS = {};
private final Path path;
private final OpenOption[] options;
private final boolean followLinks;
private PathByteSource(Path path, OpenOption... options) {
this.path = checkNotNull(path);
this.options = options.clone();
this.followLinks = followLinks(this.options);
// TODO(cgdecker): validate the provided options... for example, just WRITE seems wrong
}
private static boolean followLinks(OpenOption[] options) {
for (OpenOption option : options) {
if (option == NOFOLLOW_LINKS) {
return false;
}
}
return true;
}
@Override
public InputStream openStream() throws IOException {
return Files.newInputStream(path, options);
}
private BasicFileAttributes readAttributes() throws IOException {
return Files.readAttributes(
path,
BasicFileAttributes.class,
followLinks ? FOLLOW_LINKS : new LinkOption[] {NOFOLLOW_LINKS});
}
@Override
public Optional<Long> sizeIfKnown() {
BasicFileAttributes attrs;
try {
attrs = readAttributes();
} catch (IOException e) {
// Failed to get attributes; we don't know the size.
return Optional.absent();
}
// Don't return a size for directories or symbolic links; their sizes are implementation
// specific and they can't be read as bytes using the read methods anyway.
if (attrs.isDirectory() || attrs.isSymbolicLink()) {
return Optional.absent();
}
return Optional.of(attrs.size());
}
@Override
public long size() throws IOException {
BasicFileAttributes attrs = readAttributes();
// Don't return a size for directories or symbolic links; their sizes are implementation
// specific and they can't be read as bytes using the read methods anyway.
if (attrs.isDirectory()) {
throw new IOException("can't read: is a directory");
} else if (attrs.isSymbolicLink()) {
throw new IOException("can't read: is a symbolic link");
}
return attrs.size();
}
@Override
public byte[] read() throws IOException {
try (SeekableByteChannel channel = Files.newByteChannel(path, options)) {
return ByteStreams.toByteArray(Channels.newInputStream(channel), channel.size());
}
}
@Override
public CharSource asCharSource(Charset charset) {
if (options.length == 0) {
// If no OpenOptions were passed, delegate to Files.lines, which could have performance
// advantages. (If OpenOptions were passed we can't, because Files.lines doesn't have an
// overload taking OpenOptions, meaning we can't guarantee the same behavior w.r.t. things
// like following/not following symlinks.
return new AsCharSource(charset) {
@SuppressWarnings("FilesLinesLeak") // the user needs to close it in this case
@Override
public Stream<String> lines() throws IOException {
return Files.lines(path, charset);
}
};
}
return super.asCharSource(charset);
}
@Override
public String toString() {
return "MoreFiles.asByteSource(" + path + ", " + Arrays.toString(options) + ")";
}
}
/**
* Returns a view of the given {@code path} as a {@link ByteSink}.
*
* <p>Any {@linkplain OpenOption open options} provided are used when opening streams to the file
* and may affect the behavior of the returned sink and the streams it provides. See {@link
* StandardOpenOption} for the standard options that may be provided. Providing no options is
* equivalent to providing the {@link StandardOpenOption#CREATE CREATE}, {@link
* StandardOpenOption#TRUNCATE_EXISTING TRUNCATE_EXISTING} and {@link StandardOpenOption#WRITE
* WRITE} options.
*/
public static ByteSink asByteSink(Path path, OpenOption... options) {
return new PathByteSink(path, options);
}
private static final class PathByteSink extends ByteSink {
private final Path path;
private final OpenOption[] options;
private PathByteSink(Path path, OpenOption... options) {
this.path = checkNotNull(path);
this.options = options.clone();
// TODO(cgdecker): validate the provided options... for example, just READ seems wrong
}
@Override
public OutputStream openStream() throws IOException {
return Files.newOutputStream(path, options);
}
@Override
public String toString() {
return "MoreFiles.asByteSink(" + path + ", " + Arrays.toString(options) + ")";
}
}
/**
* Returns a view of the given {@code path} as a {@link CharSource} using the given {@code
* charset}.
*
* <p>Any {@linkplain OpenOption open options} provided are used when opening streams to the file
* and may affect the behavior of the returned source and the streams it provides. See {@link
* StandardOpenOption} for the standard options that may be provided. Providing no options is
* equivalent to providing the {@link StandardOpenOption#READ READ} option.
*/
public static CharSource asCharSource(Path path, Charset charset, OpenOption... options) {
return asByteSource(path, options).asCharSource(charset);
}
/**
* Returns a view of the given {@code path} as a {@link CharSink} using the given {@code charset}.
*
* <p>Any {@linkplain OpenOption open options} provided are used when opening streams to the file
* and may affect the behavior of the returned sink and the streams it provides. See {@link
* StandardOpenOption} for the standard options that may be provided. Providing no options is
* equivalent to providing the {@link StandardOpenOption#CREATE CREATE}, {@link
* StandardOpenOption#TRUNCATE_EXISTING TRUNCATE_EXISTING} and {@link StandardOpenOption#WRITE
* WRITE} options.
*/
public static CharSink asCharSink(Path path, Charset charset, OpenOption... options) {
return asByteSink(path, options).asCharSink(charset);
}
/**
* Returns an immutable list of paths to the files contained in the given directory.
*
* @throws NoSuchFileException if the file does not exist <i>(optional specific exception)</i>
* @throws NotDirectoryException if the file could not be opened because it is not a directory
* <i>(optional specific exception)</i>
* @throws IOException if an I/O error occurs
*/
public static ImmutableList<Path> listFiles(Path dir) throws IOException {
try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir)) {
return ImmutableList.copyOf(stream);
} catch (DirectoryIteratorException e) {
throw e.getCause();
}
}
/**
* Returns a {@link Traverser} instance for the file and directory tree. The returned traverser
* starts from a {@link Path} and will return all files and directories it encounters.
*
* <p>The returned traverser attempts to avoid following symbolic links to directories. However,
* the traverser cannot guarantee that it will not follow symbolic links to directories as it is
* possible for a directory to be replaced with a symbolic link between checking if the file is a
* directory and actually reading the contents of that directory.
*
* <p>If the {@link Path} passed to one of the traversal methods does not exist or is not a
* directory, no exception will be thrown and the returned {@link Iterable} will contain a single
* element: that path.
*
* <p>{@link DirectoryIteratorException} may be thrown when iterating {@link Iterable} instances
* created by this traverser if an {@link IOException} is thrown by a call to {@link
* #listFiles(Path)}.
*
* <p>Example: {@code MoreFiles.fileTraverser().depthFirstPreOrder(Paths.get("/"))} may return the
* following paths: {@code ["/", "/etc", "/etc/config.txt", "/etc/fonts", "/home", "/home/alice",
* ...]}
*
* @since 23.5
*/
public static Traverser<Path> fileTraverser() {
return Traverser.forTree(FILE_TREE);
}
private static final SuccessorsFunction<Path> FILE_TREE =
new SuccessorsFunction<Path>() {
@Override
public Iterable<Path> successors(Path path) {
return fileTreeChildren(path);
}
};
private static Iterable<Path> fileTreeChildren(Path dir) {
if (Files.isDirectory(dir, NOFOLLOW_LINKS)) {
try {
return listFiles(dir);
} catch (IOException e) {
// the exception thrown when iterating a DirectoryStream if an I/O exception occurs
throw new DirectoryIteratorException(e);
}
}
return ImmutableList.of();
}
/**
* Returns a predicate that returns the result of {@link java.nio.file.Files#isDirectory(Path,
* LinkOption...)} on input paths with the given link options.
*/
public static Predicate<Path> isDirectory(LinkOption... options) {
final LinkOption[] optionsCopy = options.clone();
return new Predicate<Path>() {
@Override
public boolean apply(Path input) {
return Files.isDirectory(input, optionsCopy);
}
@Override
public String toString() {
return "MoreFiles.isDirectory(" + Arrays.toString(optionsCopy) + ")";
}
};
}
/** Returns whether or not the file with the given name in the given dir is a directory. */
private static boolean isDirectory(
SecureDirectoryStream<Path> dir, Path name, LinkOption... options) throws IOException {
return dir.getFileAttributeView(name, BasicFileAttributeView.class, options)
.readAttributes()
.isDirectory();
}
/**
* Returns a predicate that returns the result of {@link java.nio.file.Files#isRegularFile(Path,
* LinkOption...)} on input paths with the given link options.
*/
public static Predicate<Path> isRegularFile(LinkOption... options) {
final LinkOption[] optionsCopy = options.clone();
return new Predicate<Path>() {
@Override
public boolean apply(Path input) {
return Files.isRegularFile(input, optionsCopy);
}
@Override
public String toString() {
return "MoreFiles.isRegularFile(" + Arrays.toString(optionsCopy) + ")";
}
};
}
/**
* Returns true if the files located by the given paths exist, are not directories, and contain
* the same bytes.
*
* @throws IOException if an I/O error occurs
* @since 22.0
*/
public static boolean equal(Path path1, Path path2) throws IOException {
checkNotNull(path1);
checkNotNull(path2);
if (Files.isSameFile(path1, path2)) {
return true;
}
/*
* Some operating systems may return zero as the length for files denoting system-dependent
* entities such as devices or pipes, in which case we must fall back on comparing the bytes
* directly.
*/
ByteSource source1 = asByteSource(path1);
ByteSource source2 = asByteSource(path2);
long len1 = source1.sizeIfKnown().or(0L);
long len2 = source2.sizeIfKnown().or(0L);
if (len1 != 0 && len2 != 0 && len1 != len2) {
return false;
}
return source1.contentEquals(source2);
}
/**
* Like the unix command of the same name, creates an empty file or updates the last modified
* timestamp of the existing file at the given path to the current system time.
*/
@SuppressWarnings("GoodTime") // reading system time without TimeSource
public static void touch(Path path) throws IOException {
checkNotNull(path);
try {
Files.setLastModifiedTime(path, FileTime.fromMillis(System.currentTimeMillis()));
} catch (NoSuchFileException e) {
try {
Files.createFile(path);
} catch (FileAlreadyExistsException ignore) {
// The file didn't exist when we called setLastModifiedTime, but it did when we called
// createFile, so something else created the file in between. The end result is
// what we wanted: a new file that probably has its last modified time set to approximately
// now. Or it could have an arbitrary last modified time set by the creator, but that's no
// different than if another process set its last modified time to something else after we
// created it here.
}
}
}
/**
* Creates any necessary but nonexistent parent directories of the specified path. Note that if
* this operation fails, it may have succeeded in creating some (but not all) of the necessary
* parent directories. The parent directory is created with the given {@code attrs}.
*
* @throws IOException if an I/O error occurs, or if any necessary but nonexistent parent
* directories of the specified file could not be created.
*/
public static void createParentDirectories(Path path, FileAttribute<?>... attrs)
throws IOException {
// Interestingly, unlike File.getCanonicalFile(), Path/Files provides no way of getting the
// canonical (absolute, normalized, symlinks resolved, etc.) form of a path to a nonexistent
// file. getCanonicalFile() can at least get the canonical form of the part of the path which
// actually exists and then append the normalized remainder of the path to that.
Path normalizedAbsolutePath = path.toAbsolutePath().normalize();
Path parent = normalizedAbsolutePath.getParent();
if (parent == null) {
// The given directory is a filesystem root. All zero of its ancestors exist. This doesn't
// mean that the root itself exists -- consider x:\ on a Windows machine without such a
// drive -- or even that the caller can create it, but this method makes no such guarantees
// even for non-root files.
return;
}
// Check if the parent is a directory first because createDirectories will fail if the parent
// exists and is a symlink to a directory... we'd like for this to succeed in that case.
// (I'm kind of surprised that createDirectories would fail in that case; doesn't seem like
// what you'd want to happen.)
if (!Files.isDirectory(parent)) {
Files.createDirectories(parent, attrs);
if (!Files.isDirectory(parent)) {
throw new IOException("Unable to create parent directories of " + path);
}
}
}
/**
* Returns the <a href="http://en.wikipedia.org/wiki/Filename_extension">file extension</a> for
* the file at the given path, or the empty string if the file has no extension. The result does
* not include the '{@code .}'.
*
* <p><b>Note:</b> This method simply returns everything after the last '{@code .}' in the file's
* name as determined by {@link Path#getFileName}. It does not account for any filesystem-specific
* behavior that the {@link Path} API does not already account for. For example, on NTFS it will
* report {@code "txt"} as the extension for the filename {@code "foo.exe:.txt"} even though NTFS
* will drop the {@code ":.txt"} part of the name when the file is actually created on the
* filesystem due to NTFS's <a href="https://goo.gl/vTpJi4">Alternate Data Streams</a>.
*/
public static String getFileExtension(Path path) {
Path name = path.getFileName();
// null for empty paths and root-only paths
if (name == null) {
return "";
}
String fileName = name.toString();
int dotIndex = fileName.lastIndexOf('.');
return dotIndex == -1 ? "" : fileName.substring(dotIndex + 1);
}
/**
* Returns the file name without its <a
* href="http://en.wikipedia.org/wiki/Filename_extension">file extension</a> or path. This is
* similar to the {@code basename} unix command. The result does not include the '{@code .}'.
*/
public static String getNameWithoutExtension(Path path) {
Path name = path.getFileName();
// null for empty paths and root-only paths
if (name == null) {
return "";
}
String fileName = name.toString();
int dotIndex = fileName.lastIndexOf('.');
return dotIndex == -1 ? fileName : fileName.substring(0, dotIndex);
}
/**
* Deletes the file or directory at the given {@code path} recursively. Deletes symbolic links,
* not their targets (subject to the caveat below).
*
* <p>If an I/O exception occurs attempting to read, open or delete any file under the given
* directory, this method skips that file and continues. All such exceptions are collected and,
* after attempting to delete all files, an {@code IOException} is thrown containing those
* exceptions as {@linkplain Throwable#getSuppressed() suppressed exceptions}.
*
* <h2>Warning: Security of recursive deletes</h2>
*
* <p>On a file system that supports symbolic links and does <i>not</i> support {@link
* SecureDirectoryStream}, it is possible for a recursive delete to delete files and directories
* that are <i>outside</i> the directory being deleted. This can happen if, after checking that a
* file is a directory (and not a symbolic link), that directory is replaced by a symbolic link to
* an outside directory before the call that opens the directory to read its entries.
*
* <p>By default, this method throws {@link InsecureRecursiveDeleteException} if it can't
* guarantee the security of recursive deletes. If you wish to allow the recursive deletes anyway,
* pass {@link RecursiveDeleteOption#ALLOW_INSECURE} to this method to override that behavior.
*
* @throws NoSuchFileException if {@code path} does not exist <i>(optional specific exception)</i>
* @throws InsecureRecursiveDeleteException if the security of recursive deletes can't be
* guaranteed for the file system and {@link RecursiveDeleteOption#ALLOW_INSECURE} was not
* specified
* @throws IOException if {@code path} or any file in the subtree rooted at it can't be deleted
* for any reason
*/
public static void deleteRecursively(Path path, RecursiveDeleteOption... options)
throws IOException {
Path parentPath = getParentPath(path);
if (parentPath == null) {
throw new FileSystemException(path.toString(), null, "can't delete recursively");
}
Collection<IOException> exceptions = null; // created lazily if needed
try {
boolean sdsSupported = false;
try (DirectoryStream<Path> parent = Files.newDirectoryStream(parentPath)) {
if (parent instanceof SecureDirectoryStream) {
sdsSupported = true;
exceptions =
deleteRecursivelySecure(
(SecureDirectoryStream<Path>) parent,
/*
* requireNonNull is safe because paths have file names when they have parents,
* and we checked for a parent at the beginning of the method.
*/
requireNonNull(path.getFileName()));
}
}
if (!sdsSupported) {
checkAllowsInsecure(path, options);
exceptions = deleteRecursivelyInsecure(path);
}
} catch (IOException e) {
if (exceptions == null) {
throw e;
} else {
exceptions.add(e);
}
}
if (exceptions != null) {
throwDeleteFailed(path, exceptions);
}
}
/**
* Deletes all files within the directory at the given {@code path} {@linkplain #deleteRecursively
* recursively}. Does not delete the directory itself. Deletes symbolic links, not their targets
* (subject to the caveat below). If {@code path} itself is a symbolic link to a directory, that
* link is followed and the contents of the directory it targets are deleted.
*
* <p>If an I/O exception occurs attempting to read, open or delete any file under the given
* directory, this method skips that file and continues. All such exceptions are collected and,
* after attempting to delete all files, an {@code IOException} is thrown containing those
* exceptions as {@linkplain Throwable#getSuppressed() suppressed exceptions}.
*
* <h2>Warning: Security of recursive deletes</h2>
*
* <p>On a file system that supports symbolic links and does <i>not</i> support {@link
* SecureDirectoryStream}, it is possible for a recursive delete to delete files and directories
* that are <i>outside</i> the directory being deleted. This can happen if, after checking that a
* file is a directory (and not a symbolic link), that directory is replaced by a symbolic link to
* an outside directory before the call that opens the directory to read its entries.
*
* <p>By default, this method throws {@link InsecureRecursiveDeleteException} if it can't
* guarantee the security of recursive deletes. If you wish to allow the recursive deletes anyway,
* pass {@link RecursiveDeleteOption#ALLOW_INSECURE} to this method to override that behavior.
*
* @throws NoSuchFileException if {@code path} does not exist <i>(optional specific exception)</i>
* @throws NotDirectoryException if the file at {@code path} is not a directory <i>(optional
* specific exception)</i>
* @throws InsecureRecursiveDeleteException if the security of recursive deletes can't be
* guaranteed for the file system and {@link RecursiveDeleteOption#ALLOW_INSECURE} was not
* specified
* @throws IOException if one or more files can't be deleted for any reason
*/
public static void deleteDirectoryContents(Path path, RecursiveDeleteOption... options)
throws IOException {
Collection<IOException> exceptions = null; // created lazily if needed
try (DirectoryStream<Path> stream = Files.newDirectoryStream(path)) {
if (stream instanceof SecureDirectoryStream) {
SecureDirectoryStream<Path> sds = (SecureDirectoryStream<Path>) stream;
exceptions = deleteDirectoryContentsSecure(sds);
} else {
checkAllowsInsecure(path, options);
exceptions = deleteDirectoryContentsInsecure(stream);
}
} catch (IOException e) {
if (exceptions == null) {
throw e;
} else {
exceptions.add(e);
}
}
if (exceptions != null) {
throwDeleteFailed(path, exceptions);
}
}
/**
* Secure recursive delete using {@code SecureDirectoryStream}. Returns a collection of exceptions
* that occurred or null if no exceptions were thrown.
*/
@CheckForNull
private static Collection<IOException> deleteRecursivelySecure(
SecureDirectoryStream<Path> dir, Path path) {
Collection<IOException> exceptions = null;
try {
if (isDirectory(dir, path, NOFOLLOW_LINKS)) {
try (SecureDirectoryStream<Path> childDir = dir.newDirectoryStream(path, NOFOLLOW_LINKS)) {
exceptions = deleteDirectoryContentsSecure(childDir);
}
// If exceptions is not null, something went wrong trying to delete the contents of the
// directory, so we shouldn't try to delete the directory as it will probably fail.
if (exceptions == null) {
dir.deleteDirectory(path);
}
} else {
dir.deleteFile(path);
}
return exceptions;
} catch (IOException e) {
return addException(exceptions, e);
}
}
/**
* Secure method for deleting the contents of a directory using {@code SecureDirectoryStream}.
* Returns a collection of exceptions that occurred or null if no exceptions were thrown.
*/
@CheckForNull
private static Collection<IOException> deleteDirectoryContentsSecure(
SecureDirectoryStream<Path> dir) {
Collection<IOException> exceptions = null;
try {
for (Path path : dir) {
exceptions = concat(exceptions, deleteRecursivelySecure(dir, path.getFileName()));
}
return exceptions;
} catch (DirectoryIteratorException e) {
return addException(exceptions, e.getCause());
}
}
/**
* Insecure recursive delete for file systems that don't support {@code SecureDirectoryStream}.
* Returns a collection of exceptions that occurred or null if no exceptions were thrown.
*/
@CheckForNull
private static Collection<IOException> deleteRecursivelyInsecure(Path path) {
Collection<IOException> exceptions = null;
try {
if (Files.isDirectory(path, NOFOLLOW_LINKS)) {
try (DirectoryStream<Path> stream = Files.newDirectoryStream(path)) {
exceptions = deleteDirectoryContentsInsecure(stream);
}
}
// If exceptions is not null, something went wrong trying to delete the contents of the
// directory, so we shouldn't try to delete the directory as it will probably fail.
if (exceptions == null) {
Files.delete(path);
}
return exceptions;
} catch (IOException e) {
return addException(exceptions, e);
}
}
/**
* Simple, insecure method for deleting the contents of a directory for file systems that don't
* support {@code SecureDirectoryStream}. Returns a collection of exceptions that occurred or null
* if no exceptions were thrown.
*/
@CheckForNull
private static Collection<IOException> deleteDirectoryContentsInsecure(
DirectoryStream<Path> dir) {
Collection<IOException> exceptions = null;
try {
for (Path entry : dir) {
exceptions = concat(exceptions, deleteRecursivelyInsecure(entry));
}
return exceptions;
} catch (DirectoryIteratorException e) {
return addException(exceptions, e.getCause());
}
}
/**
* Returns a path to the parent directory of the given path. If the path actually has a parent
* path, this is simple. Otherwise, we need to do some trickier things. Returns null if the path
* is a root or is the empty path.
*/
@CheckForNull
private static Path getParentPath(Path path) {
Path parent = path.getParent();
// Paths that have a parent:
if (parent != null) {
// "/foo" ("/")
// "foo/bar" ("foo")
// "C:\foo" ("C:\")
// "\foo" ("\" - current drive for process on Windows)
// "C:foo" ("C:" - working dir of drive C on Windows)
return parent;
}
// Paths that don't have a parent:
if (path.getNameCount() == 0) {
// "/", "C:\", "\" (no parent)
// "" (undefined, though typically parent of working dir)
// "C:" (parent of working dir of drive C on Windows)
//
// For working dir paths ("" and "C:"), return null because:
// A) it's not specified that "" is the path to the working directory.
// B) if we're getting this path for recursive delete, it's typically not possible to
// delete the working dir with a relative path anyway, so it's ok to fail.
// C) if we're getting it for opening a new SecureDirectoryStream, there's no need to get
// the parent path anyway since we can safely open a DirectoryStream to the path without
// worrying about a symlink.
return null;
} else {
// "foo" (working dir)
return path.getFileSystem().getPath(".");
}
}
/** Checks that the given options allow an insecure delete, throwing an exception if not. */
private static void checkAllowsInsecure(Path path, RecursiveDeleteOption[] options)
throws InsecureRecursiveDeleteException {
if (!Arrays.asList(options).contains(RecursiveDeleteOption.ALLOW_INSECURE)) {
throw new InsecureRecursiveDeleteException(path.toString());
}
}
/**
* Adds the given exception to the given collection, creating the collection if it's null. Returns
* the collection.
*/
private static Collection<IOException> addException(
@CheckForNull Collection<IOException> exceptions, IOException e) {
if (exceptions == null) {
exceptions = new ArrayList<>(); // don't need Set semantics
}
exceptions.add(e);
return exceptions;
}
/**
* Concatenates the contents of the two given collections of exceptions. If either collection is
* null, the other collection is returned. Otherwise, the elements of {@code other} are added to
* {@code exceptions} and {@code exceptions} is returned.
*/
@CheckForNull
private static Collection<IOException> concat(
@CheckForNull Collection<IOException> exceptions,
@CheckForNull Collection<IOException> other) {
if (exceptions == null) {
return other;
} else if (other != null) {
exceptions.addAll(other);
}
return exceptions;
}
/**
* Throws an exception indicating that one or more files couldn't be deleted when deleting {@code
* path} or its contents.
*
* <p>If there is only one exception in the collection, and it is a {@link NoSuchFileException}
* thrown because {@code path} itself didn't exist, then throws that exception. Otherwise, the
* thrown exception contains all the exceptions in the given collection as suppressed exceptions.
*/
private static void throwDeleteFailed(Path path, Collection<IOException> exceptions)
throws FileSystemException {
NoSuchFileException pathNotFound = pathNotFound(path, exceptions);
if (pathNotFound != null) {
throw pathNotFound;
}
// TODO(cgdecker): Should there be a custom exception type for this?
// Also, should we try to include the Path of each file we may have failed to delete rather
// than just the exceptions that occurred?
FileSystemException deleteFailed =
new FileSystemException(
path.toString(),
null,
"failed to delete one or more files; see suppressed exceptions for details");
for (IOException e : exceptions) {
deleteFailed.addSuppressed(e);
}
throw deleteFailed;
}
@CheckForNull
private static NoSuchFileException pathNotFound(Path path, Collection<IOException> exceptions) {
if (exceptions.size() != 1) {
return null;
}
IOException exception = getOnlyElement(exceptions);
if (!(exception instanceof NoSuchFileException)) {
return null;
}
NoSuchFileException noSuchFileException = (NoSuchFileException) exception;
String exceptionFile = noSuchFileException.getFile();
if (exceptionFile == null) {
/*
* It's not clear whether this happens in practice, especially with the filesystem
* implementations that are built into java.nio.
*/
return null;
}
Path parentPath = getParentPath(path);
if (parentPath == null) {
/*
* This is probably impossible:
*
* - In deleteRecursively, we require the path argument to have a parent.
*
* - In deleteDirectoryContents, the path argument may have no parent. Fortunately, all the
* *other* paths we process will be descendants of that. That leaves only the original path
* argument for us to consider. And the only place we call pathNotFound is from
* throwDeleteFailed, and the other place that we call throwDeleteFailed inside
* deleteDirectoryContents is when an exception is thrown during the recursive steps. Any
* failure during the initial lookup of the path argument itself is rethrown directly. So
* any exception that we're seeing here is from a descendant, which naturally has a parent.
* I think.
*
* Still, if this can happen somehow (a weird filesystem implementation that lets callers
* change its working directly concurrently with a call to deleteDirectoryContents?), it makes
* more sense for us to fall back to a generic FileSystemException (by returning null here)
* than to dereference parentPath and end up producing NullPointerException.
*/
return null;
}
// requireNonNull is safe because paths have file names when they have parents.
Path pathResolvedFromParent = parentPath.resolve(requireNonNull(path.getFileName()));
if (exceptionFile.equals(pathResolvedFromParent.toString())) {
return noSuchFileException;
}
return null;
}
}