diff options
Diffstat (limited to 'jimfs/src/main/java/com/google/common/jimfs/UserDefinedAttributeProvider.java')
-rw-r--r-- | jimfs/src/main/java/com/google/common/jimfs/UserDefinedAttributeProvider.java | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/jimfs/src/main/java/com/google/common/jimfs/UserDefinedAttributeProvider.java b/jimfs/src/main/java/com/google/common/jimfs/UserDefinedAttributeProvider.java new file mode 100644 index 0000000..51cbfa6 --- /dev/null +++ b/jimfs/src/main/java/com/google/common/jimfs/UserDefinedAttributeProvider.java @@ -0,0 +1,162 @@ +/* + * 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); + } + } +} |