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/*
* Copyright 2013 Google Inc.
*
* 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.jimfs;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.nio.file.attribute.FileAttributeView;
import java.nio.file.attribute.FileTime;
import java.nio.file.attribute.GroupPrincipal;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.UserPrincipal;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
/**
* Attribute provider that provides the "unix" attribute view.
*
* @author Colin Decker
*/
final class UnixAttributeProvider extends AttributeProvider {
private static final ImmutableSet<String> ATTRIBUTES =
ImmutableSet.of("uid", "ino", "dev", "nlink", "rdev", "ctime", "mode", "gid");
private static final ImmutableSet<String> INHERITED_VIEWS =
ImmutableSet.of("basic", "owner", "posix");
private final AtomicInteger uidGenerator = new AtomicInteger();
private final ConcurrentMap<Object, Integer> idCache = new ConcurrentHashMap<>();
@Override
public String name() {
return "unix";
}
@Override
public ImmutableSet<String> inherits() {
return INHERITED_VIEWS;
}
@Override
public ImmutableSet<String> fixedAttributes() {
return ATTRIBUTES;
}
@Override
public Class<UnixFileAttributeView> viewType() {
return UnixFileAttributeView.class;
}
@Override
public UnixFileAttributeView view(
FileLookup lookup, ImmutableMap<String, FileAttributeView> inheritedViews) {
// This method should not be called... and it cannot be called through the public APIs in
// java.nio.file since there is no public UnixFileAttributeView type.
throw new UnsupportedOperationException();
}
// TODO(cgdecker): Since we can now guarantee that the owner/group for an file are our own
// implementation of UserPrincipal/GroupPrincipal, it would be nice to have them store a unique
// ID themselves and just get that rather than doing caching here. Then this could be a singleton
// like the rest of the AttributeProviders. However, that would require a way for the owner/posix
// providers to create their default principals using the lookup service for the specific file
// system.
/** Returns an ID that is guaranteed to be the same for any invocation with equal objects. */
private Integer getUniqueId(Object object) {
Integer id = idCache.get(object);
if (id == null) {
id = uidGenerator.incrementAndGet();
Integer existing = idCache.putIfAbsent(object, id);
if (existing != null) {
return existing;
}
}
return id;
}
@SuppressWarnings("unchecked")
@Override
public Object get(File file, String attribute) {
switch (attribute) {
case "uid":
UserPrincipal user = (UserPrincipal) file.getAttribute("owner", "owner");
return getUniqueId(user);
case "gid":
GroupPrincipal group = (GroupPrincipal) file.getAttribute("posix", "group");
return getUniqueId(group);
case "mode":
Set<PosixFilePermission> permissions =
(Set<PosixFilePermission>) file.getAttribute("posix", "permissions");
return toMode(permissions);
case "ctime":
return FileTime.fromMillis(file.getCreationTime());
case "rdev":
return 0L;
case "dev":
return 1L;
case "ino":
return file.id();
case "nlink":
return file.links();
default:
return null;
}
}
@Override
public void set(File file, String view, String attribute, Object value, boolean create) {
throw unsettable(view, attribute, create);
}
@SuppressWarnings("OctalInteger")
private static int toMode(Set<PosixFilePermission> permissions) {
int result = 0;
for (PosixFilePermission permission : permissions) {
checkNotNull(permission);
switch (permission) {
case OWNER_READ:
result |= 0400; // note: octal numbers
break;
case OWNER_WRITE:
result |= 0200;
break;
case OWNER_EXECUTE:
result |= 0100;
break;
case GROUP_READ:
result |= 0040;
break;
case GROUP_WRITE:
result |= 0020;
break;
case GROUP_EXECUTE:
result |= 0010;
break;
case OTHERS_READ:
result |= 0004;
break;
case OTHERS_WRITE:
result |= 0002;
break;
case OTHERS_EXECUTE:
result |= 0001;
break;
default:
throw new AssertionError(); // no other possible values
}
}
return result;
}
}
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