PermissionUtils.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.tools.ant.util;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.attribute.PosixFileAttributeView;
import java.nio.file.attribute.PosixFilePermission;
import java.util.EnumSet;
import java.util.Set;
import java.util.function.Consumer;
import java.util.function.Function;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.resources.ArchiveResource;
import org.apache.tools.ant.types.resources.FileProvider;
/**
* Contains helper methods for dealing with {@link
* PosixFilePermission} or the traditional Unix mode representation of
* permissions.
*
* @since Ant 1.10.0
*/
public class PermissionUtils {
private PermissionUtils() { }
/**
* Translates a set of permissions into a Unix stat(2) {@code
* st_mode} result.
* @param permissions the permissions
* @param type the file type
* @return the "mode"
*/
public static int modeFromPermissions(Set<PosixFilePermission> permissions,
FileType type) {
int mode;
switch (type) {
case SYMLINK:
mode = 012;
break;
case REGULAR_FILE:
mode = 010;
break;
case DIR:
mode = 004;
break;
default:
// OTHER could be a character or block device, a socket or a FIFO - so don't set anything
mode = 0;
break;
}
mode <<= 3;
mode <<= 3; // we don't support sticky, setuid, setgid
mode |= modeFromPermissions(permissions, "OWNER");
mode <<= 3;
mode |= modeFromPermissions(permissions, "GROUP");
mode <<= 3;
mode |= modeFromPermissions(permissions, "OTHERS");
return mode;
}
/**
* Translates a Unix stat(2) {@code st_mode} compatible value into
* a set of permissions.
* @param mode the "mode"
* @return set of permissions
*/
public static Set<PosixFilePermission> permissionsFromMode(int mode) {
Set<PosixFilePermission> permissions = EnumSet.noneOf(PosixFilePermission.class);
addPermissions(permissions, "OTHERS", mode);
addPermissions(permissions, "GROUP", mode >> 3);
addPermissions(permissions, "OWNER", mode >> 6);
return permissions;
}
/**
* Sets permissions on a {@link Resource} - doesn't do anything
* for unsupported resource types.
*
* <p>Supported types are:</p>
* <ul>
* <li>any {@link FileProvider}</li>
* <li>{@link ArchiveResource}</li>
* </ul>
*
* @param r the resource to set permissions for
* @param permissions the permissions
* @param posixNotSupportedCallback optional callback that is
* invoked for a file provider resource if the file-system holding
* the file doesn't support PosixFilePermissions. The Path
* corresponding to the file is passed to the callback.
* @throws IOException if something goes wrong
*/
public static void setPermissions(Resource r, Set<PosixFilePermission> permissions,
Consumer<Path> posixNotSupportedCallback)
throws IOException {
FileProvider f = r.as(FileProvider.class);
if (f != null) {
Path p = f.getFile().toPath();
PosixFileAttributeView view =
Files.getFileAttributeView(p, PosixFileAttributeView.class);
if (view != null) {
view.setPermissions(permissions);
} else if (posixNotSupportedCallback != null) {
posixNotSupportedCallback.accept(p);
}
} else if (r instanceof ArchiveResource) {
((ArchiveResource) r).setMode(modeFromPermissions(permissions,
FileType.of(r)));
}
}
/**
* Sets permissions of a {@link Resource} - returns an empty set
* for unsupported resource types or file systems that don't
* support PosixFilePermissions and no fallback has been
* provided..
*
* <p>Supported types are:</p>
* <ul>
* <li>any {@link FileProvider}</li>
* <li>{@link ArchiveResource}</li>
* </ul>
*
* @param r the resource to read permissions from
* @param posixNotSupportedFallback optional fallback function to provide
* permissions for file system that don't support
* PosixFilePermissions. The Path corresponding to the file is
* passed to the callback.
* @return the permissions
* @throws IOException if something goes wrong
*/
public static Set<PosixFilePermission> getPermissions(Resource r,
Function<Path, Set<PosixFilePermission>> posixNotSupportedFallback)
throws IOException {
FileProvider f = r.as(FileProvider.class);
if (f != null) {
Path p = f.getFile().toPath();
PosixFileAttributeView view =
Files.getFileAttributeView(p, PosixFileAttributeView.class);
if (view != null) {
return view.readAttributes().permissions();
} else if (posixNotSupportedFallback != null) {
return posixNotSupportedFallback.apply(p);
}
} else if (r instanceof ArchiveResource) {
return permissionsFromMode(((ArchiveResource) r).getMode());
}
return EnumSet.noneOf(PosixFilePermission.class);
}
private static long modeFromPermissions(Set<PosixFilePermission> permissions,
String prefix) {
long mode = 0;
if (permissions.contains(PosixFilePermission.valueOf(prefix + "_READ"))) {
mode |= 4;
}
if (permissions.contains(PosixFilePermission.valueOf(prefix + "_WRITE"))) {
mode |= 2;
}
if (permissions.contains(PosixFilePermission.valueOf(prefix + "_EXECUTE"))) {
mode |= 1;
}
return mode;
}
private static void addPermissions(Set<PosixFilePermission> permissions,
String prefix, long mode) {
if ((mode & 1) == 1) {
permissions.add(PosixFilePermission.valueOf(prefix + "_EXECUTE"));
}
if ((mode & 2) == 2) {
permissions.add(PosixFilePermission.valueOf(prefix + "_WRITE"));
}
if ((mode & 4) == 4) {
permissions.add(PosixFilePermission.valueOf(prefix + "_READ"));
}
}
/**
* The supported types of files, maps to the {@code isFoo} methods
* in {@link java.nio.file.attribute.BasicFileAttributes}.
*/
public enum FileType {
/** A regular file. */
REGULAR_FILE,
/** A directory. */
DIR,
/** A symbolic link. */
SYMLINK,
/** Something that is neither a regular file nor a directory nor a symbolic link. */
OTHER;
/**
* Determines the file type of a {@link Path}.
*
* @param p Path
* @return FileType
* @throws IOException if file attributes cannot be read
*/
public static FileType of(Path p) throws IOException {
BasicFileAttributes attrs =
Files.readAttributes(p, BasicFileAttributes.class);
if (attrs.isRegularFile()) {
return FileType.REGULAR_FILE;
} else if (attrs.isDirectory()) {
return FileType.DIR;
} else if (attrs.isSymbolicLink()) {
return FileType.SYMLINK;
}
return FileType.OTHER;
}
/**
* Determines the file type of a {@link Resource}.
*
* @param r Resource
* @return FileType
*/
public static FileType of(Resource r) {
if (r.isDirectory()) {
return FileType.DIR;
}
return FileType.REGULAR_FILE;
}
}
}