// Copyright 2014 The Bazel Authors. All rights reserved.
//
// 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.devtools.build.lib.vfs;
import com.google.common.annotations.VisibleForTesting;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.profiler.Profiler;
import com.google.devtools.build.lib.profiler.ProfilerTask;
import com.google.devtools.build.lib.util.Clock;
import com.google.devtools.build.lib.util.JavaClock;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.ArrayList;
import java.util.Collection;
/**
* A FileSystem that does not use any JNI and hence, does not require a shared library be present at
* execution.
*
* <p>Note: Blaze profiler tasks are defined on the system call level - thus we do not distinguish
* (from profiling perspective) between different methods on this class that end up doing stat()
* system call - they all are associated with the VFS_STAT task.
*/
@ThreadSafe
public class JavaIoFileSystem extends AbstractFileSystemWithCustomStat {
private static final LinkOption[] NO_LINK_OPTION = new LinkOption[0];
// This isn't generally safe; we rely on the file system APIs not modifying the array.
private static final LinkOption[] NOFOLLOW_LINKS_OPTION =
new LinkOption[] { LinkOption.NOFOLLOW_LINKS };
private final Clock clock;
protected static final String ERR_IS_DIRECTORY = " (Is a directory)";
protected static final String ERR_DIRECTORY_NOT_EMPTY = " (Directory not empty)";
protected static final String ERR_FILE_EXISTS = " (File exists)";
protected static final String ERR_NO_SUCH_FILE_OR_DIR = " (No such file or directory)";
protected static final String ERR_NOT_A_DIRECTORY = " (Not a directory)";
public JavaIoFileSystem() {
this(new JavaClock());
}
@VisibleForTesting
JavaIoFileSystem(Clock clock) {
this.clock = clock;
}
protected File getIoFile(Path path) {
return new File(path.toString());
}
private LinkOption[] linkOpts(boolean followSymlinks) {
return followSymlinks ? NO_LINK_OPTION : NOFOLLOW_LINKS_OPTION;
}
@Override
protected Collection<Path> getDirectoryEntries(Path path) throws IOException {
File file = getIoFile(path);
String[] entries = null;
long startTime = Profiler.nanoTimeMaybe();
try {
entries = file.list();
if (entries == null) {
if (file.exists()) {
throw new IOException(path + ERR_NOT_A_DIRECTORY);
} else {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
}
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_DIR, file.getPath());
}
Collection<Path> result = new ArrayList<>(entries.length);
for (String entry : entries) {
if (!entry.equals(".") && !entry.equals("..")) {
result.add(path.getChild(entry));
}
}
return result;
}
@Override
protected boolean exists(Path path, boolean followSymlinks) {
File file = getIoFile(path);
long startTime = Profiler.nanoTimeMaybe();
try {
return Files.exists(file.toPath(), linkOpts(followSymlinks));
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, path.toString());
}
}
@Override
protected boolean isReadable(Path path) throws IOException {
File file = getIoFile(path);
long startTime = Profiler.nanoTimeMaybe();
try {
if (!file.exists()) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
return file.canRead();
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, file.getPath());
}
}
@Override
protected boolean isWritable(Path path) throws IOException {
File file = getIoFile(path);
long startTime = Profiler.nanoTimeMaybe();
try {
if (!file.exists()) {
if (linkExists(file)) {
throw new IOException(path + ERR_PERMISSION_DENIED);
} else {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
}
return file.canWrite();
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, file.getPath());
}
}
@Override
protected boolean isExecutable(Path path) throws IOException {
File file = getIoFile(path);
long startTime = Profiler.nanoTimeMaybe();
try {
if (!file.exists()) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
return file.canExecute();
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, file.getPath());
}
}
@Override
protected void setReadable(Path path, boolean readable) throws IOException {
File file = getIoFile(path);
if (!file.exists()) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
file.setReadable(readable);
}
@Override
protected void setWritable(Path path, boolean writable) throws IOException {
File file = getIoFile(path);
if (!file.exists()) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
file.setWritable(writable);
}
@Override
protected void setExecutable(Path path, boolean executable) throws IOException {
File file = getIoFile(path);
if (!file.exists()) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
file.setExecutable(executable);
}
@Override
public boolean supportsModifications() {
return true;
}
@Override
public boolean supportsSymbolicLinksNatively() {
return true;
}
@Override
public boolean supportsHardLinksNatively() {
return true;
}
@Override
public boolean isFilePathCaseSensitive() {
return true;
}
@Override
protected boolean createDirectory(Path path) throws IOException {
// We always synchronize on the current path before doing it on the parent path and file system
// path structure ensures that this locking order will never be reversed.
// When refactoring, check that subclasses still work as expected and there can be no
// deadlocks.
synchronized (path) {
File file = getIoFile(path);
if (file.mkdir()) {
return true;
}
// We will be checking the state of the parent path as well. Synchronize on it before
// attempting anything.
Path parentDirectory = path.getParentDirectory();
synchronized (parentDirectory) {
if (fileIsSymbolicLink(file)) {
throw new IOException(path + ERR_FILE_EXISTS);
}
if (file.isDirectory()) {
return false; // directory already existed
} else if (file.exists()) {
throw new IOException(path + ERR_FILE_EXISTS);
} else if (!file.getParentFile().exists()) {
throw new FileNotFoundException(path.getParentDirectory() + ERR_NO_SUCH_FILE_OR_DIR);
}
// Parent directory apparently exists - try to create our directory again - protecting
// against the case where parent directory would be created right before us obtaining
// synchronization lock.
if (file.mkdir()) {
return true; // Everything is fine finally.
} else if (!file.getParentFile().canWrite()) {
throw new FileAccessException(path + ERR_PERMISSION_DENIED);
} else {
// Parent exists, is writable, yet we can't create our directory.
throw new FileNotFoundException(path.getParentDirectory() + ERR_NOT_A_DIRECTORY);
}
}
}
}
private boolean linkExists(File file) {
String shortName = file.getName();
File parentFile = file.getParentFile();
if (parentFile == null) {
return false;
}
String[] filenames = parentFile.list();
if (filenames == null) {
return false;
}
for (String name : filenames) {
if (name.equals(shortName)) {
return true;
}
}
return false;
}
@Override
protected void createSymbolicLink(Path linkPath, PathFragment targetFragment)
throws IOException {
File file = getIoFile(linkPath);
try {
Files.createSymbolicLink(file.toPath(), new File(targetFragment.getPathString()).toPath());
} catch (java.nio.file.FileAlreadyExistsException e) {
throw new IOException(linkPath + ERR_FILE_EXISTS);
} catch (java.nio.file.AccessDeniedException e) {
throw new IOException(linkPath + ERR_PERMISSION_DENIED);
} catch (java.nio.file.NoSuchFileException e) {
throw new FileNotFoundException(linkPath + ERR_NO_SUCH_FILE_OR_DIR);
}
}
@Override
protected PathFragment readSymbolicLink(Path path) throws IOException {
File file = getIoFile(path);
long startTime = Profiler.nanoTimeMaybe();
try {
String link = Files.readSymbolicLink(file.toPath()).toString();
return PathFragment.create(link);
} catch (java.nio.file.NotLinkException e) {
throw new NotASymlinkException(path);
} catch (java.nio.file.NoSuchFileException e) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_READLINK, file.getPath());
}
}
@Override
protected void renameTo(Path sourcePath, Path targetPath) throws IOException {
synchronized (sourcePath) {
File sourceFile = getIoFile(sourcePath);
File targetFile = getIoFile(targetPath);
if (!sourceFile.renameTo(targetFile)) {
if (!sourceFile.exists()) {
throw new FileNotFoundException(sourcePath + ERR_NO_SUCH_FILE_OR_DIR);
}
if (targetFile.exists()) {
if (targetFile.isDirectory() && targetFile.list().length > 0) {
throw new IOException(targetPath + ERR_DIRECTORY_NOT_EMPTY);
} else if (sourceFile.isDirectory() && targetFile.isFile()) {
throw new IOException(sourcePath + " -> " + targetPath + ERR_NOT_A_DIRECTORY);
} else if (sourceFile.isFile() && targetFile.isDirectory()) {
throw new IOException(sourcePath + " -> " + targetPath + ERR_IS_DIRECTORY);
} else {
throw new IOException(sourcePath + " -> " + targetPath + ERR_PERMISSION_DENIED);
}
} else {
throw new FileAccessException(sourcePath + " -> " + targetPath + ERR_PERMISSION_DENIED);
}
}
}
}
@Override
protected long getFileSize(Path path, boolean followSymlinks) throws IOException {
long startTime = Profiler.nanoTimeMaybe();
try {
return stat(path, followSymlinks).getSize();
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, path);
}
}
@Override
protected boolean delete(Path path) throws IOException {
File file = getIoFile(path);
long startTime = Profiler.nanoTimeMaybe();
synchronized (path) {
try {
if (file.delete()) {
return true;
}
if (file.exists()) {
if (file.isDirectory() && file.list().length > 0) {
throw new IOException(path + ERR_DIRECTORY_NOT_EMPTY);
} else {
throw new IOException(path + ERR_PERMISSION_DENIED);
}
}
return false;
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_DELETE, file.getPath());
}
}
}
@Override
protected long getLastModifiedTime(Path path, boolean followSymlinks) throws IOException {
File file = getIoFile(path);
long startTime = Profiler.nanoTimeMaybe();
try {
return stat(path, followSymlinks).getLastModifiedTime();
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, file.getPath());
}
}
protected boolean fileIsSymbolicLink(File file) {
return Files.isSymbolicLink(file.toPath());
}
@Override
protected void setLastModifiedTime(Path path, long newTime) throws IOException {
File file = getIoFile(path);
if (!file.setLastModified(newTime == -1L ? clock.currentTimeMillis() : newTime)) {
if (!file.exists()) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
} else if (!file.getParentFile().canWrite()) {
throw new FileAccessException(path.getParentDirectory() + ERR_PERMISSION_DENIED);
} else {
throw new FileAccessException(path + ERR_PERMISSION_DENIED);
}
}
}
@Override
protected byte[] getMD5Digest(Path path) throws IOException {
String name = path.toString();
long startTime = Profiler.nanoTimeMaybe();
try {
return super.getMD5Digest(path);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_MD5, name);
}
}
/**
* Returns the status of a file. See {@link Path#stat(Symlinks)} for
* specification.
*
* <p>The default implementation of this method is a "lazy" one, based on
* other accessor methods such as {@link #isFile}, etc. Subclasses may provide
* more efficient specializations. However, we still try to follow Unix-like
* semantics of failing fast in case of non-existent files (or in case of
* permission issues).
*/
@Override
protected FileStatus stat(final Path path, final boolean followSymlinks) throws IOException {
File file = getIoFile(path);
final BasicFileAttributes attributes;
try {
attributes = Files.readAttributes(
file.toPath(), BasicFileAttributes.class, linkOpts(followSymlinks));
} catch (java.nio.file.FileSystemException e) {
throw new FileNotFoundException(path + ERR_NO_SUCH_FILE_OR_DIR);
}
FileStatus status = new FileStatus() {
@Override
public boolean isFile() {
return attributes.isRegularFile() || isSpecialFile();
}
@Override
public boolean isSpecialFile() {
return attributes.isOther();
}
@Override
public boolean isDirectory() {
return attributes.isDirectory();
}
@Override
public boolean isSymbolicLink() {
return attributes.isSymbolicLink();
}
@Override
public long getSize() throws IOException {
return attributes.size();
}
@Override
public long getLastModifiedTime() throws IOException {
return attributes.lastModifiedTime().toMillis();
}
@Override
public long getLastChangeTime() {
// This is the best we can do with Java NIO...
return attributes.lastModifiedTime().toMillis();
}
@Override
public long getNodeId() {
// TODO(bazel-team): Consider making use of attributes.fileKey().
return -1;
}
};
return status;
}
@Override
protected FileStatus statIfFound(Path path, boolean followSymlinks) {
try {
return stat(path, followSymlinks);
} catch (FileNotFoundException e) {
// JavaIoFileSystem#stat (incorrectly) only throws FileNotFoundException (because it calls
// #getLastModifiedTime, which can only throw a FileNotFoundException), so we always hit this
// codepath. Thus, this method will incorrectly not throw an exception for some filesystem
// errors.
return null;
} catch (IOException e) {
// If this codepath is ever hit, then this method should be rewritten to properly distinguish
// between not-found exceptions and others.
throw new IllegalStateException(e);
}
}
@Override
protected void createFSDependentHardLink(Path linkPath, Path originalPath)
throws IOException {
Files.createLink(
java.nio.file.Paths.get(linkPath.toString()),
java.nio.file.Paths.get(originalPath.toString()));
}
}