// 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.unix;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.Lists;
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.unix.NativePosixFiles.Dirents;
import com.google.devtools.build.lib.unix.NativePosixFiles.ReadTypes;
import com.google.devtools.build.lib.util.Preconditions;
import com.google.devtools.build.lib.vfs.AbstractFileSystemWithCustomStat;
import com.google.devtools.build.lib.vfs.Dirent;
import com.google.devtools.build.lib.vfs.FileStatus;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
/**
* This class implements the FileSystem interface using direct calls to the UNIX filesystem.
*/
@ThreadSafe
public class UnixFileSystem extends AbstractFileSystemWithCustomStat {
public UnixFileSystem() {
}
/**
* Eager implementation of FileStatus for file systems that have an atomic
* stat(2) syscall. A proxy for {@link com.google.devtools.build.lib.unix.FileStatus}.
* Note that isFile and getLastModifiedTime have slightly different meanings
* between UNIX and VFS.
*/
@VisibleForTesting
protected static class UnixFileStatus implements FileStatus {
private final com.google.devtools.build.lib.unix.FileStatus status;
UnixFileStatus(com.google.devtools.build.lib.unix.FileStatus status) {
this.status = status;
}
@Override
public boolean isFile() { return !isDirectory() && !isSymbolicLink(); }
@Override
public boolean isDirectory() { return status.isDirectory(); }
@Override
public boolean isSymbolicLink() { return status.isSymbolicLink(); }
@Override
public boolean isSpecialFile() { return isFile() && !status.isRegularFile(); }
@Override
public long getSize() { return status.getSize(); }
@Override
public long getLastModifiedTime() {
return (status.getLastModifiedTime() * 1000)
+ (status.getFractionalLastModifiedTime() / 1000000);
}
@Override
public long getLastChangeTime() {
return (status.getLastChangeTime() * 1000)
+ (status.getFractionalLastChangeTime() / 1000000);
}
@Override
public long getNodeId() {
// Note that we may want to include more information in this id number going forward,
// especially the device number.
return status.getInodeNumber();
}
int getPermissions() { return status.getPermissions(); }
@Override
public String toString() { return status.toString(); }
}
@Override
protected Collection<Path> getDirectoryEntries(Path path) throws IOException {
String name = path.getPathString();
String[] entries;
long startTime = Profiler.nanoTimeMaybe();
try {
entries = NativePosixFiles.readdir(name);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_DIR, name);
}
Collection<Path> result = new ArrayList<>(entries.length);
for (String entry : entries) {
result.add(path.getChild(entry));
}
return result;
}
@Override
protected PathFragment resolveOneLink(Path path) throws IOException {
// Beware, this seemingly simple code belies the complex specification of
// FileSystem.resolveOneLink().
return stat(path, false).isSymbolicLink()
? readSymbolicLink(path)
: null;
}
/**
* Converts from {@link com.google.devtools.build.lib.unix.NativePosixFiles.Dirents.Type} to
* {@link com.google.devtools.build.lib.vfs.Dirent.Type}.
*/
private static Dirent.Type convertToDirentType(Dirents.Type type) {
switch (type) {
case FILE:
return Dirent.Type.FILE;
case DIRECTORY:
return Dirent.Type.DIRECTORY;
case SYMLINK:
return Dirent.Type.SYMLINK;
case UNKNOWN:
return Dirent.Type.UNKNOWN;
default:
throw new IllegalArgumentException("Unknown type " + type);
}
}
@Override
protected Collection<Dirent> readdir(Path path, boolean followSymlinks) throws IOException {
String name = path.getPathString();
long startTime = Profiler.nanoTimeMaybe();
try {
Dirents unixDirents = NativePosixFiles.readdir(name,
followSymlinks ? ReadTypes.FOLLOW : ReadTypes.NOFOLLOW);
Preconditions.checkState(unixDirents.hasTypes());
List<Dirent> dirents = Lists.newArrayListWithCapacity(unixDirents.size());
for (int i = 0; i < unixDirents.size(); i++) {
dirents.add(new Dirent(unixDirents.getName(i),
convertToDirentType(unixDirents.getType(i))));
}
return dirents;
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_DIR, name);
}
}
@Override
protected FileStatus stat(Path path, boolean followSymlinks) throws IOException {
return statInternal(path, followSymlinks);
}
@VisibleForTesting
protected UnixFileStatus statInternal(Path path, boolean followSymlinks) throws IOException {
String name = path.getPathString();
long startTime = Profiler.nanoTimeMaybe();
try {
return new UnixFileStatus(followSymlinks
? NativePosixFiles.stat(name)
: NativePosixFiles.lstat(name));
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, name);
}
}
// Like stat(), but returns null instead of throwing.
// This is a performance optimization in the case where clients
// catch and don't re-throw.
@Override
protected FileStatus statNullable(Path path, boolean followSymlinks) {
String name = path.getPathString();
long startTime = Profiler.nanoTimeMaybe();
try {
ErrnoFileStatus stat = followSymlinks
? NativePosixFiles.errnoStat(name)
: NativePosixFiles.errnoLstat(name);
return stat.hasError() ? null : new UnixFileStatus(stat);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, name);
}
}
@Override
protected boolean exists(Path path, boolean followSymlinks) {
return statNullable(path, followSymlinks) != null;
}
/**
* Return true iff the {@code stat} of {@code path} resulted in an {@code ENOENT}
* or {@code ENOTDIR} error.
*/
@Override
protected FileStatus statIfFound(Path path, boolean followSymlinks) throws IOException {
String name = path.getPathString();
long startTime = Profiler.nanoTimeMaybe();
try {
ErrnoFileStatus stat = followSymlinks
? NativePosixFiles.errnoStat(name)
: NativePosixFiles.errnoLstat(name);
if (!stat.hasError()) {
return new UnixFileStatus(stat);
}
int errno = stat.getErrno();
if (errno == ErrnoFileStatus.ENOENT || errno == ErrnoFileStatus.ENOTDIR) {
return null;
}
// This should not return -- we are calling stat here just to throw the proper exception.
// However, since there may be transient IO errors, we cannot guarantee that an exception will
// be thrown.
// TODO(bazel-team): Extract the exception-construction code and make it visible separately in
// FilesystemUtils to avoid having to do a duplicate stat call.
return stat(path, followSymlinks);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_STAT, name);
}
}
@Override
protected boolean isReadable(Path path) throws IOException {
return (statInternal(path, true).getPermissions() & 0400) != 0;
}
@Override
protected boolean isWritable(Path path) throws IOException {
return (statInternal(path, true).getPermissions() & 0200) != 0;
}
@Override
protected boolean isExecutable(Path path) throws IOException {
return (statInternal(path, true).getPermissions() & 0100) != 0;
}
/**
* Adds or remove the bits specified in "permissionBits" to the permission
* mask of the file specified by {@code path}. If the argument {@code add} is
* true, the specified permissions are added, otherwise they are removed.
*
* @throws IOException if there was an error writing the file's metadata
*/
private void modifyPermissionBits(Path path, int permissionBits, boolean add)
throws IOException {
synchronized (path) {
int oldMode = statInternal(path, true).getPermissions();
int newMode = add ? (oldMode | permissionBits) : (oldMode & ~permissionBits);
NativePosixFiles.chmod(path.toString(), newMode);
}
}
@Override
protected void setReadable(Path path, boolean readable) throws IOException {
modifyPermissionBits(path, 0400, readable);
}
@Override
protected void setWritable(Path path, boolean writable) throws IOException {
modifyPermissionBits(path, 0200, writable);
}
@Override
protected void setExecutable(Path path, boolean executable) throws IOException {
modifyPermissionBits(path, 0111, executable);
}
@Override
protected void chmod(Path path, int mode) throws IOException {
synchronized (path) {
NativePosixFiles.chmod(path.toString(), mode);
}
}
@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 {
synchronized (path) {
// Note: UNIX mkdir(2), FilesystemUtils.mkdir() and createDirectory all
// have different ways of representing failure!
if (NativePosixFiles.mkdir(path.toString(), 0777)) {
return true; // successfully created
}
// false => EEXIST: something is already in the way (file/dir/symlink)
if (isDirectory(path, false)) {
return false; // directory already existed
} else {
throw new IOException(path + " (File exists)");
}
}
}
@Override
protected void createSymbolicLink(Path linkPath, PathFragment targetFragment)
throws IOException {
synchronized (linkPath) {
NativePosixFiles.symlink(targetFragment.toString(), linkPath.toString());
}
}
@Override
protected PathFragment readSymbolicLink(Path path) throws IOException {
// Note that the default implementation of readSymbolicLinkUnchecked calls this method and thus
// is optimal since we only make one system call in here.
String name = path.toString();
long startTime = Profiler.nanoTimeMaybe();
try {
return PathFragment.create(NativePosixFiles.readlink(name));
} catch (IOException e) {
// EINVAL => not a symbolic link. Anything else is a real error.
throw e.getMessage().endsWith("(Invalid argument)") ? new NotASymlinkException(path) : e;
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_READLINK, name);
}
}
@Override
protected void renameTo(Path sourcePath, Path targetPath) throws IOException {
synchronized (sourcePath) {
NativePosixFiles.rename(sourcePath.toString(), targetPath.toString());
}
}
@Override
protected long getFileSize(Path path, boolean followSymlinks) throws IOException {
return stat(path, followSymlinks).getSize();
}
@Override
protected boolean delete(Path path) throws IOException {
String name = path.toString();
long startTime = Profiler.nanoTimeMaybe();
synchronized (path) {
try {
return NativePosixFiles.remove(name);
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_DELETE, name);
}
}
}
@Override
protected long getLastModifiedTime(Path path, boolean followSymlinks) throws IOException {
return stat(path, followSymlinks).getLastModifiedTime();
}
@Override
protected void setLastModifiedTime(Path path, long newTime) throws IOException {
synchronized (path) {
if (newTime == -1L) { // "now"
NativePosixFiles.utime(path.toString(), true, 0);
} else {
// newTime > MAX_INT => -ve unixTime
int unixTime = (int) (newTime / 1000);
NativePosixFiles.utime(path.toString(), false, unixTime);
}
}
}
@Override
protected byte[] getxattr(Path path, String name) throws IOException {
String pathName = path.toString();
long startTime = Profiler.nanoTimeMaybe();
try {
return NativePosixFiles.getxattr(pathName, name);
} catch (UnsupportedOperationException e) {
// getxattr() syscall is not supported by the underlying filesystem (it returned ENOTSUP).
// Per method contract, treat this as ENODATA.
return null;
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_XATTR, pathName);
}
}
@Override
protected byte[] getMD5Digest(Path path) throws IOException {
String name = path.toString();
long startTime = Profiler.nanoTimeMaybe();
try {
return NativePosixFiles.md5sum(name).asBytes();
} finally {
profiler.logSimpleTask(startTime, ProfilerTask.VFS_MD5, name);
}
}
@Override
protected void createFSDependentHardLink(Path linkPath, Path originalPath)
throws IOException {
NativePosixFiles.link(originalPath.toString(), linkPath.toString());
}
}