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Diffstat (limited to 'java/src/main/java/com/google/protobuf/ExtensionRegistry.java')
| -rw-r--r-- | java/src/main/java/com/google/protobuf/ExtensionRegistry.java | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/java/src/main/java/com/google/protobuf/ExtensionRegistry.java b/java/src/main/java/com/google/protobuf/ExtensionRegistry.java new file mode 100644 index 0000000..87bbd6e --- /dev/null +++ b/java/src/main/java/com/google/protobuf/ExtensionRegistry.java @@ -0,0 +1,261 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// http://code.google.com/p/protobuf/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +package com.google.protobuf; + +import com.google.protobuf.Descriptors.Descriptor; +import com.google.protobuf.Descriptors.FieldDescriptor; + +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; + +/** + * A table of known extensions, searchable by name or field number. When + * parsing a protocol message that might have extensions, you must provide + * an {@code ExtensionRegistry} in which you have registered any extensions + * that you want to be able to parse. Otherwise, those extensions will just + * be treated like unknown fields. + * + * <p>For example, if you had the {@code .proto} file: + * + * <pre> + * option java_class = "MyProto"; + * + * message Foo { + * extensions 1000 to max; + * } + * + * extend Foo { + * optional int32 bar; + * } + * </pre> + * + * Then you might write code like: + * + * <pre> + * ExtensionRegistry registry = ExtensionRegistry.newInstance(); + * registry.add(MyProto.bar); + * MyProto.Foo message = MyProto.Foo.parseFrom(input, registry); + * </pre> + * + * <p>Background: + * + * <p>You might wonder why this is necessary. Two alternatives might come to + * mind. First, you might imagine a system where generated extensions are + * automatically registered when their containing classes are loaded. This + * is a popular technique, but is bad design; among other things, it creates a + * situation where behavior can change depending on what classes happen to be + * loaded. It also introduces a security vulnerability, because an + * unprivileged class could cause its code to be called unexpectedly from a + * privileged class by registering itself as an extension of the right type. + * + * <p>Another option you might consider is lazy parsing: do not parse an + * extension until it is first requested, at which point the caller must + * provide a type to use. This introduces a different set of problems. First, + * it would require a mutex lock any time an extension was accessed, which + * would be slow. Second, corrupt data would not be detected until first + * access, at which point it would be much harder to deal with it. Third, it + * could violate the expectation that message objects are immutable, since the + * type provided could be any arbitrary message class. An unprivileged user + * could take advantage of this to inject a mutable object into a message + * belonging to privileged code and create mischief. + * + * @author kenton@google.com Kenton Varda + */ +public final class ExtensionRegistry extends ExtensionRegistryLite { + /** Construct a new, empty instance. */ + public static ExtensionRegistry newInstance() { + return new ExtensionRegistry(); + } + + /** Get the unmodifiable singleton empty instance. */ + public static ExtensionRegistry getEmptyRegistry() { + return EMPTY; + } + + /** Returns an unmodifiable view of the registry. */ + @Override + public ExtensionRegistry getUnmodifiable() { + return new ExtensionRegistry(this); + } + + /** A (Descriptor, Message) pair, returned by lookup methods. */ + public static final class ExtensionInfo { + /** The extension's descriptor. */ + public final FieldDescriptor descriptor; + + /** + * A default instance of the extension's type, if it has a message type. + * Otherwise, {@code null}. + */ + public final Message defaultInstance; + + private ExtensionInfo(final FieldDescriptor descriptor) { + this.descriptor = descriptor; + defaultInstance = null; + } + private ExtensionInfo(final FieldDescriptor descriptor, + final Message defaultInstance) { + this.descriptor = descriptor; + this.defaultInstance = defaultInstance; + } + } + + /** + * Find an extension by fully-qualified field name, in the proto namespace. + * I.e. {@code result.descriptor.fullName()} will match {@code fullName} if + * a match is found. + * + * @return Information about the extension if found, or {@code null} + * otherwise. + */ + public ExtensionInfo findExtensionByName(final String fullName) { + return extensionsByName.get(fullName); + } + + /** + * Find an extension by containing type and field number. + * + * @return Information about the extension if found, or {@code null} + * otherwise. + */ + public ExtensionInfo findExtensionByNumber(final Descriptor containingType, + final int fieldNumber) { + return extensionsByNumber.get( + new DescriptorIntPair(containingType, fieldNumber)); + } + + /** Add an extension from a generated file to the registry. */ + public void add(final GeneratedMessage.GeneratedExtension<?, ?> extension) { + if (extension.getDescriptor().getJavaType() == + FieldDescriptor.JavaType.MESSAGE) { + add(new ExtensionInfo(extension.getDescriptor(), + extension.getMessageDefaultInstance())); + } else { + add(new ExtensionInfo(extension.getDescriptor(), null)); + } + } + + /** Add a non-message-type extension to the registry by descriptor. */ + public void add(final FieldDescriptor type) { + if (type.getJavaType() == FieldDescriptor.JavaType.MESSAGE) { + throw new IllegalArgumentException( + "ExtensionRegistry.add() must be provided a default instance when " + + "adding an embedded message extension."); + } + add(new ExtensionInfo(type, null)); + } + + /** Add a message-type extension to the registry by descriptor. */ + public void add(final FieldDescriptor type, final Message defaultInstance) { + if (type.getJavaType() != FieldDescriptor.JavaType.MESSAGE) { + throw new IllegalArgumentException( + "ExtensionRegistry.add() provided a default instance for a " + + "non-message extension."); + } + add(new ExtensionInfo(type, defaultInstance)); + } + + // ================================================================= + // Private stuff. + + private ExtensionRegistry() { + this.extensionsByName = new HashMap<String, ExtensionInfo>(); + this.extensionsByNumber = new HashMap<DescriptorIntPair, ExtensionInfo>(); + } + + private ExtensionRegistry(ExtensionRegistry other) { + super(other); + this.extensionsByName = Collections.unmodifiableMap(other.extensionsByName); + this.extensionsByNumber = + Collections.unmodifiableMap(other.extensionsByNumber); + } + + private final Map<String, ExtensionInfo> extensionsByName; + private final Map<DescriptorIntPair, ExtensionInfo> extensionsByNumber; + + private ExtensionRegistry(boolean empty) { + super(ExtensionRegistryLite.getEmptyRegistry()); + this.extensionsByName = Collections.<String, ExtensionInfo>emptyMap(); + this.extensionsByNumber = + Collections.<DescriptorIntPair, ExtensionInfo>emptyMap(); + } + private static final ExtensionRegistry EMPTY = new ExtensionRegistry(true); + + private void add(final ExtensionInfo extension) { + if (!extension.descriptor.isExtension()) { + throw new IllegalArgumentException( + "ExtensionRegistry.add() was given a FieldDescriptor for a regular " + + "(non-extension) field."); + } + + extensionsByName.put(extension.descriptor.getFullName(), extension); + extensionsByNumber.put( + new DescriptorIntPair(extension.descriptor.getContainingType(), + extension.descriptor.getNumber()), + extension); + + final FieldDescriptor field = extension.descriptor; + if (field.getContainingType().getOptions().getMessageSetWireFormat() && + field.getType() == FieldDescriptor.Type.MESSAGE && + field.isOptional() && + field.getExtensionScope() == field.getMessageType()) { + // This is an extension of a MessageSet type defined within the extension + // type's own scope. For backwards-compatibility, allow it to be looked + // up by type name. + extensionsByName.put(field.getMessageType().getFullName(), extension); + } + } + + /** A (GenericDescriptor, int) pair, used as a map key. */ + private static final class DescriptorIntPair { + private final Descriptor descriptor; + private final int number; + + DescriptorIntPair(final Descriptor descriptor, final int number) { + this.descriptor = descriptor; + this.number = number; + } + + @Override + public int hashCode() { + return descriptor.hashCode() * ((1 << 16) - 1) + number; + } + @Override + public boolean equals(final Object obj) { + if (!(obj instanceof DescriptorIntPair)) { + return false; + } + final DescriptorIntPair other = (DescriptorIntPair)obj; + return descriptor == other.descriptor && number == other.number; + } + } +} |