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1 // Protocol Buffers - Google's data interchange format
2 // Copyright 2008 Google Inc.  All rights reserved.
3 //
4 // Use of this source code is governed by a BSD-style
5 // license that can be found in the LICENSE file or at
6 // https://developers.google.com/open-source/licenses/bsd
7 
8 package com.google.protobuf;
9 
10 import java.io.IOException;
11 import java.util.Iterator;
12 import java.util.Map.Entry;
13 
14 /** Schema used for proto2 messages using message_set_wireformat. */
15 @CheckReturnValue
16 final class MessageSetSchema<T> implements Schema<T> {
17   private final MessageLite defaultInstance;
18   private final UnknownFieldSchema<?, ?> unknownFieldSchema;
19   private final boolean hasExtensions;
20   private final ExtensionSchema<?> extensionSchema;
21 
MessageSetSchema( UnknownFieldSchema<?, ?> unknownFieldSchema, ExtensionSchema<?> extensionSchema, MessageLite defaultInstance)22   private MessageSetSchema(
23       UnknownFieldSchema<?, ?> unknownFieldSchema,
24       ExtensionSchema<?> extensionSchema,
25       MessageLite defaultInstance) {
26     this.unknownFieldSchema = unknownFieldSchema;
27     this.hasExtensions = extensionSchema.hasExtensions(defaultInstance);
28     this.extensionSchema = extensionSchema;
29     this.defaultInstance = defaultInstance;
30   }
31 
newSchema( UnknownFieldSchema<?, ?> unknownFieldSchema, ExtensionSchema<?> extensionSchema, MessageLite defaultInstance)32   static <T> MessageSetSchema<T> newSchema(
33       UnknownFieldSchema<?, ?> unknownFieldSchema,
34       ExtensionSchema<?> extensionSchema,
35       MessageLite defaultInstance) {
36     return new MessageSetSchema<T>(unknownFieldSchema, extensionSchema, defaultInstance);
37   }
38 
39   @SuppressWarnings("unchecked")
40   @Override
newInstance()41   public T newInstance() {
42     // TODO decide if we're keeping support for Full in schema classes and handle this
43     // better.
44     if (defaultInstance instanceof GeneratedMessageLite) {
45       return (T) ((GeneratedMessageLite<?, ?>) defaultInstance).newMutableInstance();
46     } else {
47       return (T) defaultInstance.newBuilderForType().buildPartial();
48     }
49   }
50 
51   @Override
equals(T message, T other)52   public boolean equals(T message, T other) {
53     Object messageUnknown = unknownFieldSchema.getFromMessage(message);
54     Object otherUnknown = unknownFieldSchema.getFromMessage(other);
55     if (!messageUnknown.equals(otherUnknown)) {
56       return false;
57     }
58     if (hasExtensions) {
59       FieldSet<?> messageExtensions = extensionSchema.getExtensions(message);
60       FieldSet<?> otherExtensions = extensionSchema.getExtensions(other);
61       return messageExtensions.equals(otherExtensions);
62     }
63     return true;
64   }
65 
66   @Override
hashCode(T message)67   public int hashCode(T message) {
68     int hashCode = unknownFieldSchema.getFromMessage(message).hashCode();
69     if (hasExtensions) {
70       FieldSet<?> extensions = extensionSchema.getExtensions(message);
71       hashCode = (hashCode * 53) + extensions.hashCode();
72     }
73     return hashCode;
74   }
75 
76   @Override
mergeFrom(T message, T other)77   public void mergeFrom(T message, T other) {
78     SchemaUtil.mergeUnknownFields(unknownFieldSchema, message, other);
79     if (hasExtensions) {
80       SchemaUtil.mergeExtensions(extensionSchema, message, other);
81     }
82   }
83 
84   @SuppressWarnings("unchecked")
85   @Override
writeTo(T message, Writer writer)86   public void writeTo(T message, Writer writer) throws IOException {
87     FieldSet<?> extensions = extensionSchema.getExtensions(message);
88     Iterator<?> iterator = extensions.iterator();
89     while (iterator.hasNext()) {
90       Entry<?, ?> extension = (Entry<?, ?>) iterator.next();
91       FieldSet.FieldDescriptorLite<?> fd = (FieldSet.FieldDescriptorLite<?>) extension.getKey();
92       if (fd.getLiteJavaType() != WireFormat.JavaType.MESSAGE || fd.isRepeated() || fd.isPacked()) {
93         throw new IllegalStateException("Found invalid MessageSet item.");
94       }
95       if (extension instanceof LazyField.LazyEntry) {
96         writer.writeMessageSetItem(
97             fd.getNumber(), ((LazyField.LazyEntry) extension).getField().toByteString());
98       } else {
99         writer.writeMessageSetItem(fd.getNumber(), extension.getValue());
100       }
101     }
102     writeUnknownFieldsHelper(unknownFieldSchema, message, writer);
103   }
104 
105   /**
106    * A helper method for wildcard capture of {@code unknownFieldSchema}. See:
107    * https://docs.oracle.com/javase/tutorial/java/generics/capture.html
108    */
writeUnknownFieldsHelper( UnknownFieldSchema<UT, UB> unknownFieldSchema, T message, Writer writer)109   private <UT, UB> void writeUnknownFieldsHelper(
110       UnknownFieldSchema<UT, UB> unknownFieldSchema, T message, Writer writer) throws IOException {
111     unknownFieldSchema.writeAsMessageSetTo(unknownFieldSchema.getFromMessage(message), writer);
112   }
113 
114   @SuppressWarnings("ReferenceEquality")
115   @Override
mergeFrom( T message, byte[] data, int position, int limit, ArrayDecoders.Registers registers)116   public void mergeFrom(
117       T message, byte[] data, int position, int limit, ArrayDecoders.Registers registers)
118       throws IOException {
119     // TODO decide if we're keeping support for Full in schema classes and handle this
120     // better.
121     UnknownFieldSetLite unknownFields = ((GeneratedMessageLite) message).unknownFields;
122     if (unknownFields == UnknownFieldSetLite.getDefaultInstance()) {
123       unknownFields = UnknownFieldSetLite.newInstance();
124       ((GeneratedMessageLite) message).unknownFields = unknownFields;
125     }
126     final FieldSet<GeneratedMessageLite.ExtensionDescriptor> extensions =
127         ((GeneratedMessageLite.ExtendableMessage<?, ?>) message).ensureExtensionsAreMutable();
128     GeneratedMessageLite.GeneratedExtension<?, ?> extension = null;
129     while (position < limit) {
130       position = ArrayDecoders.decodeVarint32(data, position, registers);
131       final int startTag = registers.int1;
132       if (startTag != WireFormat.MESSAGE_SET_ITEM_TAG) {
133         if (WireFormat.getTagWireType(startTag) == WireFormat.WIRETYPE_LENGTH_DELIMITED) {
134           extension =
135               (GeneratedMessageLite.GeneratedExtension<?, ?>) extensionSchema.findExtensionByNumber(
136                   registers.extensionRegistry, defaultInstance,
137                   WireFormat.getTagFieldNumber(startTag));
138           if (extension != null) {
139             position =
140                 ArrayDecoders.decodeMessageField(
141                     Protobuf.getInstance().schemaFor(
142                         extension.getMessageDefaultInstance().getClass()),
143                     data, position, limit, registers);
144             extensions.setField(extension.descriptor, registers.object1);
145           } else {
146             position =
147                 ArrayDecoders.decodeUnknownField(
148                     startTag, data, position, limit, unknownFields, registers);
149           }
150         } else {
151           position = ArrayDecoders.skipField(startTag, data, position, limit, registers);
152         }
153         continue;
154       }
155 
156       int typeId = 0;
157       ByteString rawBytes = null;
158 
159       while (position < limit) {
160         position = ArrayDecoders.decodeVarint32(data, position, registers);
161         final int tag = registers.int1;
162         final int number = WireFormat.getTagFieldNumber(tag);
163         final int wireType = WireFormat.getTagWireType(tag);
164         switch (number) {
165           case WireFormat.MESSAGE_SET_TYPE_ID:
166             if (wireType == WireFormat.WIRETYPE_VARINT) {
167               position = ArrayDecoders.decodeVarint32(data, position, registers);
168               typeId = registers.int1;
169               // TODO decide if we're keeping support for Full in schema classes and
170               // handle this better.
171               extension =
172                   (GeneratedMessageLite.GeneratedExtension<?, ?>)
173                       extensionSchema.findExtensionByNumber(
174                           registers.extensionRegistry, defaultInstance, typeId);
175               continue;
176             }
177             break;
178           case WireFormat.MESSAGE_SET_MESSAGE:
179             if (extension != null) {
180               position = ArrayDecoders.decodeMessageField(
181                   Protobuf.getInstance().schemaFor(
182                       extension.getMessageDefaultInstance().getClass()),
183                   data, position, limit, registers);
184               extensions.setField(extension.descriptor, registers.object1);
185               continue;
186             } else {
187               if (wireType == WireFormat.WIRETYPE_LENGTH_DELIMITED) {
188                 position = ArrayDecoders.decodeBytes(data, position, registers);
189                 rawBytes = (ByteString) registers.object1;
190                 continue;
191               }
192               break;
193             }
194           default:
195             break;
196         }
197         if (tag == WireFormat.MESSAGE_SET_ITEM_END_TAG) {
198           break;
199         }
200         position = ArrayDecoders.skipField(tag, data, position, limit, registers);
201       }
202 
203       if (rawBytes != null) {
204         unknownFields.storeField(
205             WireFormat.makeTag(typeId, WireFormat.WIRETYPE_LENGTH_DELIMITED), rawBytes);
206       }
207     }
208     if (position != limit) {
209       throw InvalidProtocolBufferException.parseFailure();
210     }
211   }
212 
213   @Override
mergeFrom(T message, Reader reader, ExtensionRegistryLite extensionRegistry)214   public void mergeFrom(T message, Reader reader, ExtensionRegistryLite extensionRegistry)
215       throws IOException {
216     mergeFromHelper(unknownFieldSchema, extensionSchema, message, reader, extensionRegistry);
217   }
218 
219   /**
220    * A helper method for wildcard capture of {@code unknownFieldSchema}. See:
221    * https://docs.oracle.com/javase/tutorial/java/generics/capture.html
222    */
mergeFromHelper( UnknownFieldSchema<UT, UB> unknownFieldSchema, ExtensionSchema<ET> extensionSchema, T message, Reader reader, ExtensionRegistryLite extensionRegistry)223   private <UT, UB, ET extends FieldSet.FieldDescriptorLite<ET>> void mergeFromHelper(
224       UnknownFieldSchema<UT, UB> unknownFieldSchema,
225       ExtensionSchema<ET> extensionSchema,
226       T message,
227       Reader reader,
228       ExtensionRegistryLite extensionRegistry)
229       throws IOException {
230     UB unknownFields = unknownFieldSchema.getBuilderFromMessage(message);
231     FieldSet<ET> extensions = extensionSchema.getMutableExtensions(message);
232     try {
233       while (true) {
234         final int number = reader.getFieldNumber();
235         if (number == Reader.READ_DONE) {
236           return;
237         }
238         if (parseMessageSetItemOrUnknownField(
239             reader,
240             extensionRegistry,
241             extensionSchema,
242             extensions,
243             unknownFieldSchema,
244             unknownFields)) {
245           continue;
246         }
247         // Done reading.
248         return;
249       }
250     } finally {
251       unknownFieldSchema.setBuilderToMessage(message, unknownFields);
252     }
253   }
254 
255   @Override
makeImmutable(T message)256   public void makeImmutable(T message) {
257     unknownFieldSchema.makeImmutable(message);
258     extensionSchema.makeImmutable(message);
259   }
260 
261   private <UT, UB, ET extends FieldSet.FieldDescriptorLite<ET>>
parseMessageSetItemOrUnknownField( Reader reader, ExtensionRegistryLite extensionRegistry, ExtensionSchema<ET> extensionSchema, FieldSet<ET> extensions, UnknownFieldSchema<UT, UB> unknownFieldSchema, UB unknownFields)262       boolean parseMessageSetItemOrUnknownField(
263           Reader reader,
264           ExtensionRegistryLite extensionRegistry,
265           ExtensionSchema<ET> extensionSchema,
266           FieldSet<ET> extensions,
267           UnknownFieldSchema<UT, UB> unknownFieldSchema,
268           UB unknownFields)
269           throws IOException {
270     int startTag = reader.getTag();
271     if (startTag != WireFormat.MESSAGE_SET_ITEM_TAG) {
272       if (WireFormat.getTagWireType(startTag) == WireFormat.WIRETYPE_LENGTH_DELIMITED) {
273         Object extension =
274             extensionSchema.findExtensionByNumber(
275                 extensionRegistry, defaultInstance, WireFormat.getTagFieldNumber(startTag));
276         if (extension != null) {
277           extensionSchema.parseLengthPrefixedMessageSetItem(
278               reader, extension, extensionRegistry, extensions);
279           return true;
280         } else {
281           return unknownFieldSchema.mergeOneFieldFrom(unknownFields, reader, /* currentDepth= */ 0);
282         }
283       } else {
284         return reader.skipField();
285       }
286     }
287 
288     // The wire format for MessageSet is:
289     //   message MessageSet {
290     //     repeated group Item = 1 {
291     //       required uint32 typeId = 2;
292     //       required bytes message = 3;
293     //     }
294     //   }
295     // "typeId" is the extension's field number.  The extension can only be
296     // a message type, where "message" contains the encoded bytes of that
297     // message.
298     //
299     // In practice, we will probably never see a MessageSet item in which
300     // the message appears before the type ID, or where either field does not
301     // appear exactly once.  However, in theory such cases are valid, so we
302     // should be prepared to accept them.
303 
304     int typeId = 0;
305     ByteString rawBytes = null; // If we encounter "message" before "typeId"
306     Object extension = null;
307 
308     // Read bytes from input, if we get it's type first then parse it eagerly,
309     // otherwise we store the raw bytes in a local variable.
310     loop:
311     while (true) {
312       final int number = reader.getFieldNumber();
313       if (number == Reader.READ_DONE) {
314         break;
315       }
316 
317       final int tag = reader.getTag();
318       if (tag == WireFormat.MESSAGE_SET_TYPE_ID_TAG) {
319         typeId = reader.readUInt32();
320         extension =
321             extensionSchema.findExtensionByNumber(extensionRegistry, defaultInstance, typeId);
322         continue;
323       } else if (tag == WireFormat.MESSAGE_SET_MESSAGE_TAG) {
324         if (extension != null) {
325           extensionSchema.parseLengthPrefixedMessageSetItem(
326               reader, extension, extensionRegistry, extensions);
327           continue;
328         }
329         // We haven't seen a type ID yet or we want parse message lazily.
330         rawBytes = reader.readBytes();
331         continue;
332       } else {
333         if (!reader.skipField()) {
334           break loop; // End of group
335         }
336       }
337     }
338 
339     if (reader.getTag() != WireFormat.MESSAGE_SET_ITEM_END_TAG) {
340       throw InvalidProtocolBufferException.invalidEndTag();
341     }
342 
343     // If there are any rawBytes left, it means the message content appears before the type ID.
344     if (rawBytes != null) {
345       if (extension != null) { // We known the type
346         // TODO: Instead of reading into a temporary ByteString, maybe there is a way
347         // to read directly from Reader to the submessage?
348         extensionSchema.parseMessageSetItem(rawBytes, extension, extensionRegistry, extensions);
349       } else {
350         unknownFieldSchema.addLengthDelimited(unknownFields, typeId, rawBytes);
351       }
352     }
353     return true;
354   }
355 
356   @Override
isInitialized(T message)357   public final boolean isInitialized(T message) {
358     FieldSet<?> extensions = extensionSchema.getExtensions(message);
359     return extensions.isInitialized();
360   }
361 
362   @Override
getSerializedSize(T message)363   public int getSerializedSize(T message) {
364     int size = 0;
365 
366     size += getUnknownFieldsSerializedSize(unknownFieldSchema, message);
367 
368     if (hasExtensions) {
369       size += extensionSchema.getExtensions(message).getMessageSetSerializedSize();
370     }
371 
372     return size;
373   }
374 
getUnknownFieldsSerializedSize( UnknownFieldSchema<UT, UB> schema, T message)375   private <UT, UB> int getUnknownFieldsSerializedSize(
376       UnknownFieldSchema<UT, UB> schema, T message) {
377     UT unknowns = schema.getFromMessage(message);
378     return schema.getSerializedSizeAsMessageSet(unknowns);
379   }
380 }
381