csharp/src/Google.Protobuf/ParsingPrimitivesMessages.cs - third_party/protobuf - Git at Google

 #region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 #endregion

 using System;
 using System.Buffers;
 using System.Collections.Generic;
 using System.Security;
 using Google.Protobuf.Collections;

 namespace Google.Protobuf
 {
     /// <summary>
     /// Reading and skipping messages / groups
     /// </summary>
     [SecuritySafeCritical]
     internal static class ParsingPrimitivesMessages
     {
         private static readonly byte[] ZeroLengthMessageStreamData = new byte[] { 0 };

         public static void SkipLastField(ref ReadOnlySpan<byte> buffer, ref ParserInternalState state)
         {
             if (state.lastTag == 0)
             {
                 throw new InvalidOperationException("SkipLastField cannot be called at the end of a stream");
             }
             switch (WireFormat.GetTagWireType(state.lastTag))
             {
                 case WireFormat.WireType.StartGroup:
                     SkipGroup(ref buffer, ref state, state.lastTag);
                     break;
                 case WireFormat.WireType.EndGroup:
                     throw new InvalidProtocolBufferException(
                         "SkipLastField called on an end-group tag, indicating that the corresponding start-group was missing");
                 case WireFormat.WireType.Fixed32:
                     ParsingPrimitives.ParseRawLittleEndian32(ref buffer, ref state);
                     break;
                 case WireFormat.WireType.Fixed64:
                     ParsingPrimitives.ParseRawLittleEndian64(ref buffer, ref state);
                     break;
                 case WireFormat.WireType.LengthDelimited:
                     var length = ParsingPrimitives.ParseLength(ref buffer, ref state);
                     ParsingPrimitives.SkipRawBytes(ref buffer, ref state, length);
                     break;
                 case WireFormat.WireType.Varint:
                     ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
                     break;
             }
         }

         /// <summary>
         /// Skip a group.
         /// </summary>
         public static void SkipGroup(ref ReadOnlySpan<byte> buffer, ref ParserInternalState state, uint startGroupTag)
         {
             // Note: Currently we expect this to be the way that groups are read. We could put the recursion
             // depth changes into the ReadTag method instead, potentially...
             state.recursionDepth++;
             if (state.recursionDepth >= state.recursionLimit)
             {
                 throw InvalidProtocolBufferException.RecursionLimitExceeded();
             }
             uint tag;
             while (true)
             {
                 tag = ParsingPrimitives.ParseTag(ref buffer, ref state);
                 if (tag == 0)
                 {
                     throw InvalidProtocolBufferException.TruncatedMessage();
                 }
                 // Can't call SkipLastField for this case- that would throw.
                 if (WireFormat.GetTagWireType(tag) == WireFormat.WireType.EndGroup)
                 {
                     break;
                 }
                 // This recursion will allow us to handle nested groups.
                 SkipLastField(ref buffer, ref state);
             }
             int startField = WireFormat.GetTagFieldNumber(startGroupTag);
             int endField = WireFormat.GetTagFieldNumber(tag);
             if (startField != endField)
             {
                 throw new InvalidProtocolBufferException(
                     $"Mismatched end-group tag. Started with field {startField}; ended with field {endField}");
             }
             state.recursionDepth--;
         }

         public static void ReadMessage(ref ParseContext ctx, IMessage message)
         {
             int length = ParsingPrimitives.ParseLength(ref ctx.buffer, ref ctx.state);
             if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
             {
                 throw InvalidProtocolBufferException.RecursionLimitExceeded();
             }
             int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
             ++ctx.state.recursionDepth;

             ReadRawMessage(ref ctx, message);

             CheckReadEndOfStreamTag(ref ctx.state);
             // Check that we've read exactly as much data as expected.
             if (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
             {
                 throw InvalidProtocolBufferException.TruncatedMessage();
             }
             --ctx.state.recursionDepth;
             SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);
         }

         public static KeyValuePair<TKey, TValue> ReadMapEntry<TKey, TValue>(ref ParseContext ctx, MapField<TKey, TValue>.Codec codec)
         {
             int length = ParsingPrimitives.ParseLength(ref ctx.buffer, ref ctx.state);
             if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
             {
                 throw InvalidProtocolBufferException.RecursionLimitExceeded();
             }
             int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
             ++ctx.state.recursionDepth;

             TKey key = codec.KeyCodec.DefaultValue;
             TValue value = codec.ValueCodec.DefaultValue;

             uint tag;
             while ((tag = ctx.ReadTag()) != 0)
             {
                 if (tag == codec.KeyCodec.Tag)
                 {
                     key = codec.KeyCodec.Read(ref ctx);
                 }
                 else if (tag == codec.ValueCodec.Tag)
                 {
                     value = codec.ValueCodec.Read(ref ctx);
                 }
                 else
                 {
                     SkipLastField(ref ctx.buffer, ref ctx.state);
                 }
             }

             // Corner case: a map entry with a key but no value, where the value type is a message.
             // Read it as if we'd seen input with no data (i.e. create a "default" message).
             if (value == null)
             {
                 if (ctx.state.CodedInputStream != null)
                 {
                     // the decoded message might not support parsing from ParseContext, so
                     // we need to allow fallback to the legacy MergeFrom(CodedInputStream) parsing.
                     value = codec.ValueCodec.Read(new CodedInputStream(ZeroLengthMessageStreamData));
                 }
                 else
                 {
                     ParseContext.Initialize(new ReadOnlySequence<byte>(ZeroLengthMessageStreamData), out ParseContext zeroLengthCtx);
                     value = codec.ValueCodec.Read(ref zeroLengthCtx);
                 }
             }

             CheckReadEndOfStreamTag(ref ctx.state);
             // Check that we've read exactly as much data as expected.
             if (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
             {
                 throw InvalidProtocolBufferException.TruncatedMessage();
             }
             --ctx.state.recursionDepth;
             SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);

             return new KeyValuePair<TKey, TValue>(key, value);
         }

         public static void ReadGroup(ref ParseContext ctx, IMessage message)
         {
             if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
             {
                 throw InvalidProtocolBufferException.RecursionLimitExceeded();
             }
             ++ctx.state.recursionDepth;

             uint tag = ctx.state.lastTag;
             int fieldNumber = WireFormat.GetTagFieldNumber(tag);
             ReadRawMessage(ref ctx, message);
             CheckLastTagWas(ref ctx.state, WireFormat.MakeTag(fieldNumber, WireFormat.WireType.EndGroup));

             --ctx.state.recursionDepth;
         }

         public static void ReadGroup(ref ParseContext ctx, int fieldNumber, UnknownFieldSet set)
         {
             if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
             {
                 throw InvalidProtocolBufferException.RecursionLimitExceeded();
             }
             ++ctx.state.recursionDepth;

             set.MergeGroupFrom(ref ctx);
             CheckLastTagWas(ref ctx.state, WireFormat.MakeTag(fieldNumber, WireFormat.WireType.EndGroup));

             --ctx.state.recursionDepth;
         }

         public static void ReadRawMessage(ref ParseContext ctx, IMessage message)
         {
             if (message is IBufferMessage bufferMessage)
             {
                 bufferMessage.InternalMergeFrom(ref ctx);
             }
             else
             {
                 // If we reached here, it means we've ran into a nested message with older generated code
                 // which doesn't provide the InternalMergeFrom method that takes a ParseContext.
                 // With a slight performance overhead, we can still parse this message just fine,
                 // but we need to find the original CodedInputStream instance that initiated this
                 // parsing process and make sure its internal state is up to date.
                 // Note that this performance overhead is not very high (basically copying contents of a struct)
                 // and it will only be incurred in case the application mixes older and newer generated code.
                 // Regenerating the code from .proto files will remove this overhead because it will
                 // generate the InternalMergeFrom method we need.

                 if (ctx.state.CodedInputStream == null)
                 {
                     // This can only happen when the parsing started without providing a CodedInputStream instance
                     // (e.g. ParseContext was created directly from a ReadOnlySequence).
                     // That also means that one of the new parsing APIs was used at the top level
                     // and in such case it is reasonable to require that all the nested message provide
                     // up-to-date generated code with ParseContext support (and fail otherwise).
                     throw new InvalidProtocolBufferException($"Message {message.GetType().Name} doesn't provide the generated method that enables ParseContext-based parsing. You might need to regenerate the generated protobuf code.");
                 }

                 ctx.CopyStateTo(ctx.state.CodedInputStream);
                 try
                 {
                     // fallback parse using the CodedInputStream that started current parsing tree
                     message.MergeFrom(ctx.state.CodedInputStream);
                 }
                 finally
                 {
                     ctx.LoadStateFrom(ctx.state.CodedInputStream);
                 }
             }
         }

         /// <summary>
         /// Verifies that the last call to ReadTag() returned tag 0 - in other words,
         /// we've reached the end of the stream when we expected to.
         /// </summary>
         /// <exception cref="InvalidProtocolBufferException">The
         /// tag read was not the one specified</exception>
         public static void CheckReadEndOfStreamTag(ref ParserInternalState state)
         {
             if (state.lastTag != 0)
             {
                 throw InvalidProtocolBufferException.MoreDataAvailable();
             }
         }

         private static void CheckLastTagWas(ref ParserInternalState state, uint expectedTag)
         {
             if (state.lastTag != expectedTag) {
                throw InvalidProtocolBufferException.InvalidEndTag();
             }
         }
     }
 }
	#region Copyright notice and license
	// Protocol Buffers - Google's data interchange format
	// Copyright 2008 Google Inc. All rights reserved.
	//
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file or at
	// https://developers.google.com/open-source/licenses/bsd
	#endregion

	using System;
	using System.Buffers;
	using System.Collections.Generic;
	using System.Security;
	using Google.Protobuf.Collections;

	namespace Google.Protobuf
	{
	/// <summary>
	/// Reading and skipping messages / groups
	/// </summary>
	[SecuritySafeCritical]
	internal static class ParsingPrimitivesMessages
	{
	private static readonly byte[] ZeroLengthMessageStreamData = new byte[] { 0 };

	public static void SkipLastField(ref ReadOnlySpan<byte> buffer, ref ParserInternalState state)
	{
	if (state.lastTag == 0)
	{
	throw new InvalidOperationException("SkipLastField cannot be called at the end of a stream");
	}
	switch (WireFormat.GetTagWireType(state.lastTag))
	{
	case WireFormat.WireType.StartGroup:
	SkipGroup(ref buffer, ref state, state.lastTag);
	break;
	case WireFormat.WireType.EndGroup:
	throw new InvalidProtocolBufferException(
	"SkipLastField called on an end-group tag, indicating that the corresponding start-group was missing");
	case WireFormat.WireType.Fixed32:
	ParsingPrimitives.ParseRawLittleEndian32(ref buffer, ref state);
	break;
	case WireFormat.WireType.Fixed64:
	ParsingPrimitives.ParseRawLittleEndian64(ref buffer, ref state);
	break;
	case WireFormat.WireType.LengthDelimited:
	var length = ParsingPrimitives.ParseLength(ref buffer, ref state);
	ParsingPrimitives.SkipRawBytes(ref buffer, ref state, length);
	break;
	case WireFormat.WireType.Varint:
	ParsingPrimitives.ParseRawVarint32(ref buffer, ref state);
	break;
	}
	}

	/// <summary>
	/// Skip a group.
	/// </summary>
	public static void SkipGroup(ref ReadOnlySpan<byte> buffer, ref ParserInternalState state, uint startGroupTag)
	{
	// Note: Currently we expect this to be the way that groups are read. We could put the recursion
	// depth changes into the ReadTag method instead, potentially...
	state.recursionDepth++;
	if (state.recursionDepth >= state.recursionLimit)
	{
	throw InvalidProtocolBufferException.RecursionLimitExceeded();
	}
	uint tag;
	while (true)
	{
	tag = ParsingPrimitives.ParseTag(ref buffer, ref state);
	if (tag == 0)
	{
	throw InvalidProtocolBufferException.TruncatedMessage();
	}
	// Can't call SkipLastField for this case- that would throw.
	if (WireFormat.GetTagWireType(tag) == WireFormat.WireType.EndGroup)
	{
	break;
	}
	// This recursion will allow us to handle nested groups.
	SkipLastField(ref buffer, ref state);
	}
	int startField = WireFormat.GetTagFieldNumber(startGroupTag);
	int endField = WireFormat.GetTagFieldNumber(tag);
	if (startField != endField)
	{
	throw new InvalidProtocolBufferException(
	$"Mismatched end-group tag. Started with field {startField}; ended with field {endField}");
	}
	state.recursionDepth--;
	}

	public static void ReadMessage(ref ParseContext ctx, IMessage message)
	{
	int length = ParsingPrimitives.ParseLength(ref ctx.buffer, ref ctx.state);
	if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
	{
	throw InvalidProtocolBufferException.RecursionLimitExceeded();
	}
	int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
	++ctx.state.recursionDepth;

	ReadRawMessage(ref ctx, message);

	CheckReadEndOfStreamTag(ref ctx.state);
	// Check that we've read exactly as much data as expected.
	if (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
	{
	throw InvalidProtocolBufferException.TruncatedMessage();
	}
	--ctx.state.recursionDepth;
	SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);
	}

	public static KeyValuePair<TKey, TValue> ReadMapEntry<TKey, TValue>(ref ParseContext ctx, MapField<TKey, TValue>.Codec codec)
	{
	int length = ParsingPrimitives.ParseLength(ref ctx.buffer, ref ctx.state);
	if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
	{
	throw InvalidProtocolBufferException.RecursionLimitExceeded();
	}
	int oldLimit = SegmentedBufferHelper.PushLimit(ref ctx.state, length);
	++ctx.state.recursionDepth;

	TKey key = codec.KeyCodec.DefaultValue;
	TValue value = codec.ValueCodec.DefaultValue;

	uint tag;
	while ((tag = ctx.ReadTag()) != 0)
	{
	if (tag == codec.KeyCodec.Tag)
	{
	key = codec.KeyCodec.Read(ref ctx);
	}
	else if (tag == codec.ValueCodec.Tag)
	{
	value = codec.ValueCodec.Read(ref ctx);
	}
	else
	{
	SkipLastField(ref ctx.buffer, ref ctx.state);
	}
	}

	// Corner case: a map entry with a key but no value, where the value type is a message.
	// Read it as if we'd seen input with no data (i.e. create a "default" message).
	if (value == null)
	{
	if (ctx.state.CodedInputStream != null)
	{
	// the decoded message might not support parsing from ParseContext, so
	// we need to allow fallback to the legacy MergeFrom(CodedInputStream) parsing.
	value = codec.ValueCodec.Read(new CodedInputStream(ZeroLengthMessageStreamData));
	}
	else
	{
	ParseContext.Initialize(new ReadOnlySequence<byte>(ZeroLengthMessageStreamData), out ParseContext zeroLengthCtx);
	value = codec.ValueCodec.Read(ref zeroLengthCtx);
	}
	}

	CheckReadEndOfStreamTag(ref ctx.state);
	// Check that we've read exactly as much data as expected.
	if (!SegmentedBufferHelper.IsReachedLimit(ref ctx.state))
	{
	throw InvalidProtocolBufferException.TruncatedMessage();
	}
	--ctx.state.recursionDepth;
	SegmentedBufferHelper.PopLimit(ref ctx.state, oldLimit);

	return new KeyValuePair<TKey, TValue>(key, value);
	}

	public static void ReadGroup(ref ParseContext ctx, IMessage message)
	{
	if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
	{
	throw InvalidProtocolBufferException.RecursionLimitExceeded();
	}
	++ctx.state.recursionDepth;

	uint tag = ctx.state.lastTag;
	int fieldNumber = WireFormat.GetTagFieldNumber(tag);
	ReadRawMessage(ref ctx, message);
	CheckLastTagWas(ref ctx.state, WireFormat.MakeTag(fieldNumber, WireFormat.WireType.EndGroup));

	--ctx.state.recursionDepth;
	}

	public static void ReadGroup(ref ParseContext ctx, int fieldNumber, UnknownFieldSet set)
	{
	if (ctx.state.recursionDepth >= ctx.state.recursionLimit)
	{
	throw InvalidProtocolBufferException.RecursionLimitExceeded();
	}
	++ctx.state.recursionDepth;

	set.MergeGroupFrom(ref ctx);
	CheckLastTagWas(ref ctx.state, WireFormat.MakeTag(fieldNumber, WireFormat.WireType.EndGroup));

	--ctx.state.recursionDepth;
	}

	public static void ReadRawMessage(ref ParseContext ctx, IMessage message)
	{
	if (message is IBufferMessage bufferMessage)
	{
	bufferMessage.InternalMergeFrom(ref ctx);
	}
	else
	{
	// If we reached here, it means we've ran into a nested message with older generated code
	// which doesn't provide the InternalMergeFrom method that takes a ParseContext.
	// With a slight performance overhead, we can still parse this message just fine,
	// but we need to find the original CodedInputStream instance that initiated this
	// parsing process and make sure its internal state is up to date.
	// Note that this performance overhead is not very high (basically copying contents of a struct)
	// and it will only be incurred in case the application mixes older and newer generated code.
	// Regenerating the code from .proto files will remove this overhead because it will
	// generate the InternalMergeFrom method we need.

	if (ctx.state.CodedInputStream == null)
	{
	// This can only happen when the parsing started without providing a CodedInputStream instance
	// (e.g. ParseContext was created directly from a ReadOnlySequence).
	// That also means that one of the new parsing APIs was used at the top level
	// and in such case it is reasonable to require that all the nested message provide
	// up-to-date generated code with ParseContext support (and fail otherwise).
	throw new InvalidProtocolBufferException($"Message {message.GetType().Name} doesn't provide the generated method that enables ParseContext-based parsing. You might need to regenerate the generated protobuf code.");
	}

	ctx.CopyStateTo(ctx.state.CodedInputStream);
	try
	{
	// fallback parse using the CodedInputStream that started current parsing tree
	message.MergeFrom(ctx.state.CodedInputStream);
	}
	finally
	{
	ctx.LoadStateFrom(ctx.state.CodedInputStream);
	}
	}
	}

	/// <summary>
	/// Verifies that the last call to ReadTag() returned tag 0 - in other words,
	/// we've reached the end of the stream when we expected to.
	/// </summary>
	/// <exception cref="InvalidProtocolBufferException">The
	/// tag read was not the one specified</exception>
	public static void CheckReadEndOfStreamTag(ref ParserInternalState state)
	{
	if (state.lastTag != 0)
	{
	throw InvalidProtocolBufferException.MoreDataAvailable();
	}
	}

	private static void CheckLastTagWas(ref ParserInternalState state, uint expectedTag)
	{
	if (state.lastTag != expectedTag) {
	throw InvalidProtocolBufferException.InvalidEndTag();
	}
	}
	}
	}