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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.io.IOException;
import java.nio.ByteBuffer;
import java.nio.file.attribute.FileAttributeView;
import java.nio.file.attribute.UserDefinedFileAttributeView;
import java.util.List;
/**
* Attribute provider that provides the {@link UserDefinedFileAttributeView} ("user"). Unlike most
* other attribute providers, this one has no pre-defined set of attributes. Rather, it allows
* arbitrary user defined attributes to be set (as {@code ByteBuffer} or {@code byte[]}) and read
* (as {@code byte[]}).
*
* @author Colin Decker
*/
final class UserDefinedAttributeProvider extends AttributeProvider {
UserDefinedAttributeProvider() {}
@Override
public String name() {
return "user";
}
@Override
public ImmutableSet<String> fixedAttributes() {
// no fixed set of attributes for this view
return ImmutableSet.of();
}
@Override
public boolean supports(String attribute) {
// any attribute name is supported
return true;
}
@Override
public ImmutableSet<String> attributes(File file) {
return userDefinedAttributes(file);
}
private static ImmutableSet<String> userDefinedAttributes(File file) {
ImmutableSet.Builder<String> builder = ImmutableSet.builder();
for (String attribute : file.getAttributeNames("user")) {
builder.add(attribute);
}
return builder.build();
}
@Override
public Object get(File file, String attribute) {
Object value = file.getAttribute("user", attribute);
if (value instanceof byte[]) {
byte[] bytes = (byte[]) value;
return bytes.clone();
}
return null;
}
@Override
public void set(File file, String view, String attribute, Object value, boolean create) {
checkNotNull(value);
checkNotCreate(view, attribute, create);
byte[] bytes;
if (value instanceof byte[]) {
bytes = ((byte[]) value).clone();
} else if (value instanceof ByteBuffer) {
// value instanceof ByteBuffer
ByteBuffer buffer = (ByteBuffer) value;
bytes = new byte[buffer.remaining()];
buffer.get(bytes);
} else {
throw invalidType(view, attribute, value, byte[].class, ByteBuffer.class);
}
file.setAttribute("user", attribute, bytes);
}
@Override
public Class<UserDefinedFileAttributeView> viewType() {
return UserDefinedFileAttributeView.class;
}
@Override
public UserDefinedFileAttributeView view(
FileLookup lookup, ImmutableMap<String, FileAttributeView> inheritedViews) {
return new View(lookup);
}
/** Implementation of {@link UserDefinedFileAttributeView}. */
private static class View extends AbstractAttributeView implements UserDefinedFileAttributeView {
public View(FileLookup lookup) {
super(lookup);
}
@Override
public String name() {
return "user";
}
@Override
public List<String> list() throws IOException {
return userDefinedAttributes(lookupFile()).asList();
}
private byte[] getStoredBytes(String name) throws IOException {
byte[] bytes = (byte[]) lookupFile().getAttribute(name(), name);
if (bytes == null) {
throw new IllegalArgumentException("attribute '" + name() + ":" + name + "' is not set");
}
return bytes;
}
@Override
public int size(String name) throws IOException {
return getStoredBytes(name).length;
}
@Override
public int read(String name, ByteBuffer dst) throws IOException {
byte[] bytes = getStoredBytes(name);
dst.put(bytes);
return bytes.length;
}
@Override
public int write(String name, ByteBuffer src) throws IOException {
byte[] bytes = new byte[src.remaining()];
src.get(bytes);
lookupFile().setAttribute(name(), name, bytes);
return bytes.length;
}
@Override
public void delete(String name) throws IOException {
lookupFile().deleteAttribute(name(), name);
}
}
}
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