JsonEncodingStreamWrapper.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / NetFx35 / System.ServiceModel.Web / System / Runtime / Serialization / Json / JsonEncodingStreamWrapper.cs / 1 / JsonEncodingStreamWrapper.cs
                        

                        
                            //------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------

#pragma warning disable 1634 // Stops compiler from warning about unknown warnings (for Presharp) 

namespace System.Runtime.Serialization.Json 
{ 
    using System.IO;
    using System.ServiceModel; 
    using System.Text;
    using System.Xml;
    using System.Security;
 
    // This wrapper does not support seek.
    // Supports: UTF-8, Unicode, BigEndianUnicode 
    // ASSUMPTION ([....]): This class will only be used for EITHER reading OR writing.  It can be done, it would just mean more buffers. 
    class JsonEncodingStreamWrapper : Stream
    { 
        // 
        // Review - Static fields are marked SecurityCritical or readonly to prevent
        //          data from being modified or leaked to other components in appdomain.
        //  
        [SecurityRequiresReview]
        static readonly UnicodeEncoding SafeBEUTF16 = new UnicodeEncoding(true, false, false); 
        //  
        // Review - Static fields are marked SecurityCritical or readonly to prevent
        //          data from being modified or leaked to other components in appdomain. 
        // 
        [SecurityRequiresReview]
        static readonly UnicodeEncoding SafeUTF16 = new UnicodeEncoding(false, false, false);
        //  
        // Review - Static fields are marked SecurityCritical or readonly to prevent
        //          data from being modified or leaked to other components in appdomain. 
        //  
        [SecurityRequiresReview]
        static readonly UTF8Encoding SafeUTF8 = new UTF8Encoding(false, false); 
        // 
        // Review - Static fields are marked SecurityCritical or readonly to prevent
        //          data from being modified or leaked to other components in appdomain.
        //  
        [SecurityRequiresReview]
        static readonly UnicodeEncoding ValidatingBEUTF16 = new UnicodeEncoding(true, false, true); 
        //  
        // Review - Static fields are marked SecurityCritical or readonly to prevent
        //          data from being modified or leaked to other components in appdomain. 
        // 
        [SecurityRequiresReview]
        static readonly UnicodeEncoding ValidatingUTF16 = new UnicodeEncoding(false, false, true);
        //  
        // Review - Static fields are marked SecurityCritical or readonly to prevent
        //          data from being modified or leaked to other components in appdomain. 
        //  
        [SecurityRequiresReview]
        static readonly UTF8Encoding ValidatingUTF8 = new UTF8Encoding(false, true); 
        const int BufferLength = 128;

        byte[] byteBuffer = new byte[1];
        int byteCount; 
        int byteOffset;
        byte[] bytes; 
        char[] chars; 
        Decoder dec;
        Encoder enc; 
        Encoding encoding;

        SupportedEncoding encodingCode;
        bool isReading; 

        Stream stream; 
 
        public JsonEncodingStreamWrapper(Stream stream, Encoding encoding, bool isReader)
        { 
            this.isReading = isReader;
            if (isReader)
            {
                InitForReading(stream, encoding); 
            }
            else 
            { 
                if (encoding == null)
                { 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgumentNull("encoding");
                }

                InitForWriting(stream, encoding); 
            }
        } 
 
        enum SupportedEncoding
        { 
            UTF8,
            UTF16LE,
            UTF16BE,
            None 
        }
 
        // This stream wrapper does not support duplex 
        public override bool CanRead
        { 
            get
            {
                if (!isReading)
                { 
                    return false;
                } 
 
                return this.stream.CanRead;
            } 
        }

        // The encoding conversion and buffering breaks seeking.
        public override bool CanSeek 
        {
            get {return false; } 
        } 

        // Delegate properties 
        public override bool CanTimeout
        {
            get {return this.stream.CanTimeout; }
        } 

        // This stream wrapper does not support duplex 
        public override bool CanWrite 
        {
            get 
            {
                if (isReading)
                {
                    return false; 
                }
 
                return this.stream.CanWrite; 
            }
        } 

        public override long Length
        {
            get {return this.stream.Length; } 
        }
 
 
        // The encoding conversion and buffering breaks seeking.
        public override long Position 
        {
            get
            {
#pragma warning suppress 56503 // The contract for non seekable stream is to throw exception 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new NotSupportedException());
            } 
            set {throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new NotSupportedException()); } 
        }
 
        public override int ReadTimeout
        {
            get {return this.stream.ReadTimeout; }
            set {this.stream.ReadTimeout = value; } 
        }
 
        public override int WriteTimeout 
        {
            get {return this.stream.WriteTimeout; } 
            set {this.stream.WriteTimeout = value; }
        }

        public static ArraySegment ProcessBuffer(byte[] buffer, int offset, int count, Encoding encoding) 
        {
            try 
            { 
                SupportedEncoding expectedEnc = GetSupportedEncoding(encoding);
                SupportedEncoding dataEnc; 
                if (count < 2)
                {
                    dataEnc = SupportedEncoding.UTF8;
                } 
                else
                { 
                    dataEnc = ReadEncoding(buffer[offset], buffer[offset + 1]); 
                }
                if ((expectedEnc != SupportedEncoding.None) && (expectedEnc != dataEnc)) 
                {
                    ThrowExpectedEncodingMismatch(expectedEnc, dataEnc);
                }
 
                // Fastpath: UTF-8
                if (dataEnc == SupportedEncoding.UTF8) 
                { 
                    return new ArraySegment(buffer, offset, count);
                } 

                // Convert to UTF-8
                return
                    new ArraySegment(ValidatingUTF8.GetBytes(GetEncoding(dataEnc).GetChars(buffer, offset, count))); 
            }
            catch (DecoderFallbackException e) 
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
                    new XmlException(SR2.GetString(SR2.JsonInvalidBytes), e)); 
            }
        }

        public override void Close() 
        {
            Flush(); 
            base.Close(); 
            this.stream.Close();
        } 

        public override void Flush()
        {
            this.stream.Flush(); 
        }
 
        public override int Read(byte[] buffer, int offset, int count) 
        {
            try 
            {
                if (byteCount == 0)
                {
                    if (encodingCode == SupportedEncoding.UTF8) 
                    {
                        return this.stream.Read(buffer, offset, count); 
                    } 

                    // No more bytes than can be turned into characters 
                    byteOffset = 0;
                    byteCount = this.stream.Read(bytes, byteCount, (chars.Length - 1) * 2);

                    // Check for end of stream 
                    if (byteCount == 0)
                    { 
                        return 0; 
                    }
 
                    // Fix up incomplete chars
                    CleanupCharBreak();

                    // Change encoding 
                    int charCount = this.encoding.GetChars(bytes, 0, byteCount, chars, 0);
                    byteCount = Encoding.UTF8.GetBytes(chars, 0, charCount, bytes, 0); 
                } 

                // Give them bytes 
                if (byteCount < count)
                {
                    count = byteCount;
                } 
                Buffer.BlockCopy(bytes, byteOffset, buffer, offset, count);
                byteOffset += count; 
                byteCount -= count; 
                return count;
            } 
            catch (DecoderFallbackException ex)
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
                    new XmlException(SR2.GetString(SR2.JsonInvalidBytes), ex)); 
            }
        } 
 
        public override int ReadByte()
        { 
            if (byteCount == 0 && encodingCode == SupportedEncoding.UTF8)
            {
                return this.stream.ReadByte();
            } 
            if (Read(byteBuffer, 0, 1) == 0)
            { 
                return -1; 
            }
            return byteBuffer[0]; 
        }

        public override long Seek(long offset, SeekOrigin origin)
        { 
            throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new NotSupportedException());
        } 
 
        // Delegate methods
        public override void SetLength(long value) 
        {
            throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new NotSupportedException());
        }
 
        public override void Write(byte[] buffer, int offset, int count)
        { 
            // Optimize UTF-8 case 
            if (encodingCode == SupportedEncoding.UTF8)
            { 
                this.stream.Write(buffer, offset, count);
                return;
            }
 
            while (count > 0)
            { 
                int size = chars.Length < count ? chars.Length : count; 
                int charCount = dec.GetChars(buffer, offset, size, chars, 0, false);
                byteCount = enc.GetBytes(chars, 0, charCount, bytes, 0, false); 
                this.stream.Write(bytes, 0, byteCount);
                offset += size;
                count -= size;
            } 
        }
 
        public override void WriteByte(byte b) 
        {
            if (encodingCode == SupportedEncoding.UTF8) 
            {
                this.stream.WriteByte(b);
                return;
            } 
            byteBuffer[0] = b;
            Write(byteBuffer, 0, 1); 
        } 

        static Encoding GetEncoding(SupportedEncoding e) 
        {
            switch (e)
            {
                case SupportedEncoding.UTF8: 
                    return ValidatingUTF8;
 
                case SupportedEncoding.UTF16LE: 
                    return ValidatingUTF16;
 
                case SupportedEncoding.UTF16BE:
                    return ValidatingBEUTF16;

                default: 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
                        new XmlException(SR2.GetString(SR2.JsonEncodingNotSupported))); 
            } 
        }
 
        static string GetEncodingName(SupportedEncoding enc)
        {
            switch (enc)
            { 
                case SupportedEncoding.UTF8:
                    return "utf-8"; 
 
                case SupportedEncoding.UTF16LE:
                    return "utf-16LE"; 

                case SupportedEncoding.UTF16BE:
                    return "utf-16BE";
 
                default:
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                        new XmlException(SR2.GetString(SR2.JsonEncodingNotSupported))); 
            }
        } 

        static SupportedEncoding GetSupportedEncoding(Encoding encoding)
        {
            if (encoding == null) 
            {
                return SupportedEncoding.None; 
            } 
            if (encoding.WebName == ValidatingUTF8.WebName)
            { 
                return SupportedEncoding.UTF8;
            }
            else if (encoding.WebName == ValidatingUTF16.WebName)
            { 
                return SupportedEncoding.UTF16LE;
            } 
            else if (encoding.WebName == ValidatingBEUTF16.WebName) 
            {
                return SupportedEncoding.UTF16BE; 
            }
            else
            {
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                    new XmlException(SR2.GetString(SR2.JsonEncodingNotSupported)));
            } 
        } 

        static SupportedEncoding ReadEncoding(byte b1, byte b2) 
        {
            if (b1 == 0x00 && b2 != 0x00)
            {
                return SupportedEncoding.UTF16BE; 
            }
            else if (b1 != 0x00 && b2 == 0x00) 
            { 
                // 857 It's possible to misdetect UTF-32LE as UTF-16LE, but that's OK.
                return SupportedEncoding.UTF16LE; 
            }
            else if (b1 == 0x00 && b2 == 0x00)
            {
                // UTF-32BE not supported 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new XmlException(SR2.GetString(SR2.JsonInvalidBytes)));
            } 
            else 
            {
                return SupportedEncoding.UTF8; 
            }
        }

        static void ThrowExpectedEncodingMismatch(SupportedEncoding expEnc, SupportedEncoding actualEnc) 
        {
            throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new XmlException(SR2.GetString(SR2.JsonExpectedEncoding, GetEncodingName(expEnc), GetEncodingName(actualEnc)))); 
        } 

        void CleanupCharBreak() 
        {
            int max = byteOffset + byteCount;

            // Read on 2 byte boundaries 
            if ((byteCount % 2) != 0)
            { 
                int b = this.stream.ReadByte(); 
                if (b < 0)
                { 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
                        new XmlException(SR2.GetString(SR2.JsonUnexpectedEndOfFile)));
                }
 
                bytes[max++] = (byte) b;
                byteCount++; 
            } 

            // Don't cut off a surrogate character 
            int w;
            if (encodingCode == SupportedEncoding.UTF16LE)
            {
                w = bytes[max - 2] + (bytes[max - 1] << 8); 
            }
            else 
            { 
                w = bytes[max - 1] + (bytes[max - 2] << 8);
            } 
            if ((w & 0xDC00) != 0xDC00 && w >= 0xD800 && w <= 0xDBFF) // First 16-bit number of surrogate pair
            {
                int b1 = this.stream.ReadByte();
                int b2 = this.stream.ReadByte(); 
                if (b2 < 0)
                { 
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError( 
                        new XmlException(SR2.GetString(SR2.JsonUnexpectedEndOfFile)));
                } 
                bytes[max++] = (byte) b1;
                bytes[max++] = (byte) b2;
                byteCount += 2;
            } 
        }
 
        void EnsureBuffers() 
        {
            EnsureByteBuffer(); 
            if (chars == null)
            {
                chars = new char[BufferLength];
            } 
        }
 
        void EnsureByteBuffer() 
        {
            if (bytes != null) 
            {
                return;
            }
 
            bytes = new byte[BufferLength * 4];
            byteOffset = 0; 
            byteCount = 0; 
        }
 
        void FillBuffer(int count)
        {
            count -= byteCount;
            while (count > 0) 
            {
                int read = stream.Read(bytes, byteOffset + byteCount, count); 
                if (read == 0) 
                {
                    break; 
                }

                byteCount += read;
                count -= read; 
            }
        } 
 
        void InitForReading(Stream inputStream, Encoding expectedEncoding)
        { 
            try
            {
                this.stream = new BufferedStream(inputStream);
 
                SupportedEncoding expectedEnc = GetSupportedEncoding(expectedEncoding);
                SupportedEncoding dataEnc = ReadEncoding(); 
                if ((expectedEnc != SupportedEncoding.None) && (expectedEnc != dataEnc)) 
                {
                    ThrowExpectedEncodingMismatch(expectedEnc, dataEnc); 
                }

                // Fastpath: UTF-8 (do nothing)
                if (dataEnc != SupportedEncoding.UTF8) 
                {
                    // Convert to UTF-8 
                    EnsureBuffers(); 
                    FillBuffer((BufferLength - 1) * 2);
                    this.encodingCode = dataEnc; 
                    this.encoding = GetEncoding(dataEnc);
                    CleanupCharBreak();
                    int count = this.encoding.GetChars(bytes, byteOffset, byteCount, chars, 0);
                    byteOffset = 0; 
                    byteCount = ValidatingUTF8.GetBytes(chars, 0, count, bytes, 0);
                } 
            } 
            catch (DecoderFallbackException ex)
            { 
                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(
                    new XmlException(SR2.GetString(SR2.JsonInvalidBytes), ex));
            }
        } 

        void InitForWriting(Stream outputStream, Encoding writeEncoding) 
        { 
            this.encoding = writeEncoding;
            this.stream = new BufferedStream(outputStream); 

            // Set the encoding code
            this.encodingCode = GetSupportedEncoding(writeEncoding);
 
            if (this.encodingCode != SupportedEncoding.UTF8)
            { 
                EnsureBuffers(); 
                dec = ValidatingUTF8.GetDecoder();
                enc = this.encoding.GetEncoder(); 
            }
        }

        SupportedEncoding ReadEncoding() 
        {
            int b1 = this.stream.ReadByte(); 
            int b2 = this.stream.ReadByte(); 

            EnsureByteBuffer(); 

            SupportedEncoding e;

            if (b1 == -1) 
            {
                e = SupportedEncoding.UTF8; 
                byteCount = 0; 
            }
            else if (b2 == -1) 
            {
                e = SupportedEncoding.UTF8;
                bytes[0] = (byte) b1;
                byteCount = 1; 
            }
            else 
            { 
                e = ReadEncoding((byte) b1, (byte) b2);
                bytes[0] = (byte) b1; 
                bytes[1] = (byte) b2;
                byteCount = 2;
            }
 
            return e;
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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