ZipIOLocalFileDataDescriptor.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Base / MS / Internal / IO / Zip / ZipIOLocalFileDataDescriptor.cs / 1305600 / ZipIOLocalFileDataDescriptor.cs
                        
                        
                            //------------------------------------------------------------------------------ 
//-------------   *** WARNING ***
//-------------    This file is part of a legally monitored development project.
//-------------    Do not check in changes to this project.  Do not raid bugs on this
//-------------    code in the main PS database.  Do not contact the owner of this 
//-------------    code directly.  Contact the legal team at ï¿½ZSLegalï¿½ for assistance.
//-------------   *** WARNING *** 
//----------------------------------------------------------------------------- 

//----------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// Description: 
//  This is an internal class that enables interactions with Zip archives 
//  for OPC scenarios
// 
// History:
//  11/19/2004: IgorBel: Initial creation.
//
//----------------------------------------------------------------------------- 

using System; 
using System.IO; 
using System.Diagnostics;
using System.Text; 
using System.Collections;
using System.Windows;
using MS.Internal.WindowsBase;
 
namespace MS.Internal.IO.Zip
{ 
    internal class ZipIOLocalFileDataDescriptor 
    {
        // used in streaming case 
        internal static ZipIOLocalFileDataDescriptor CreateNew()
        {
            ZipIOLocalFileDataDescriptor descriptor = new ZipIOLocalFileDataDescriptor();
            descriptor._size = _fixedMinimalRecordSizeWithSignatureZip64; 

            return descriptor; 
        } 

        internal static ZipIOLocalFileDataDescriptor ParseRecord(BinaryReader reader, 
                                    long compressedSizeFromCentralDir,
                                    long uncompressedSizeFromCentralDir,
                                    UInt32 crc32FromCentralDir,
                                    UInt16 versionNeededToExtract) 
        {
            ZipIOLocalFileDataDescriptor descriptor = new ZipIOLocalFileDataDescriptor(); 
 
            // There are 4 distinct scenario we would like to support
            //   1.based on the appnote it seems that the structure of this record is following: 
            //                  crc-32                          4 bytes
            //                  compressed size                 4 bytes (scenario 1.a has 8 bytes)
            //                  uncompressed size               4 bytes (scenario 1.a has 8 bytes)
            // 
            //   2.based on files that we have been able to examine
            //                  data descriptor signature        4 bytes  (0x08074b50) 
            //                  crc-32                                  4 bytes 
            //                  compressed size                   4 bytes (scenario 2.a has 8 bytes)
            //                  uncompressed size               4 bytes (scenario 2.a has 8 bytes) 
            //
            // we can safely assume that this record is not the last one in the file, so let's just
            // read the max Bytes required to store the largest structure , and compare results
 
            // at most we are looking at 6 * 4  = 24 bytes
            UInt32[] buffer = new UInt32[6]; 
 
            // let's try to match the smallest possible structure (3 x 4) 32 bit without signature
            buffer[0] = reader.ReadUInt32(); 
            buffer[1] = reader.ReadUInt32();
            buffer[2] = reader.ReadUInt32();

            if (descriptor.TestMatch(_signatureConstant, 
                                    crc32FromCentralDir,
                                    compressedSizeFromCentralDir, 
                                    uncompressedSizeFromCentralDir, 
                               _signatureConstant,
                                    buffer[0], 
                                    buffer[1],
                                    buffer[2]))
            {
                descriptor._size = _fixedMinimalRecordSizeWithoutSignature; 
                return descriptor;
            } 
 
            // let's try to match the next record size (4 x 4) 32 bit with signature
            buffer[3] = reader.ReadUInt32(); 
            if (descriptor.TestMatch(_signatureConstant,
                                    crc32FromCentralDir,
                                    compressedSizeFromCentralDir,
                                    uncompressedSizeFromCentralDir, 
                                 buffer[0],
                                    buffer[1], 
                                    buffer[2], 
                                    buffer[3]))
            { 
                descriptor._size = _fixedMinimalRecordSizeWithSignature;
                return descriptor;
            }
 
            // At this point prior to trying to match 64 bit structures we need to make sure that version is high enough
            if (versionNeededToExtract <  (UInt16)ZipIOVersionNeededToExtract.Zip64FileFormat) 
            { 
                throw new FileFormatException(SR.Get(SRID.CorruptedData));
            } 

            //let's try to match the 64 bit structures 64 bit without signature
            buffer[4] = reader.ReadUInt32();
            if (descriptor.TestMatch(_signatureConstant, 
                                    crc32FromCentralDir,
                                    compressedSizeFromCentralDir, 
                                    uncompressedSizeFromCentralDir, 
                                 _signatureConstant,
                                    buffer[0], 
                                    ZipIOBlockManager.ConvertToUInt64(buffer[1], buffer[2]),
                                    ZipIOBlockManager.ConvertToUInt64(buffer[3], buffer[4])))
            {
                descriptor._size = _fixedMinimalRecordSizeWithoutSignatureZip64; 
                return descriptor;
            } 
 
            //let's try to match the 64 bit structures 64 bit with signature
            buffer[5] = reader.ReadUInt32(); 
            if (descriptor.TestMatch(_signatureConstant,
                                    crc32FromCentralDir,
                                    compressedSizeFromCentralDir,
                                    uncompressedSizeFromCentralDir, 
                                 buffer[0],
                                    buffer[1], 
                                    ZipIOBlockManager.ConvertToUInt64(buffer[2], buffer[3]), 
                                    ZipIOBlockManager.ConvertToUInt64(buffer[4], buffer[5])))
            { 
                descriptor._size = _fixedMinimalRecordSizeWithSignatureZip64;
                return descriptor;
            }
 
            // we couldn't match anything at this point we need to fail
            throw new FileFormatException(SR.Get(SRID.CorruptedData)); 
        } 

        ///  
        /// Save - persist to given binary writer
        /// 
        /// 
        internal void Save(BinaryWriter writer) 
        {
            // we only supposed to be saving a brand new record which is created with signature in Zip64 Mode 
            // this only supported for streaming publishing cases. 
            // For editing scenarios we never save them (not even preserve them), as any editing (even trivial moving of record around)
            // will result in switching File Item to a non-streaming mode without data desciptor 
            Invariant.Assert(_size == _fixedMinimalRecordSizeWithSignatureZip64);

            // always persist Zip64 version signature
            writer.Write(_signatureConstant);               // this is apparently optional, but omitting it causes wzzip to complain 
            writer.Write(_crc32);
            writer.Write((UInt64)_compressedSize);          // 8 bytes 
            writer.Write((UInt64)_uncompressedSize);        // 8 bytes 
        }
 
        internal long Size
        {
            get
            { 
                return _size;
            } 
        } 

        internal UInt32 Crc32 
        {
            get
            {
                return _crc32; 
            }
            set 
            { 
                _crc32 = value;
            } 
        }

        internal long CompressedSize
        { 
            get
            { 
                return _compressedSize; 
            }
            set 
            {
                Invariant.Assert((value >= 0), "CompressedSize must be non-negative");

                _compressedSize = value; 
            }
        } 
 
        internal long UncompressedSize
        { 
            get
            {
                return _uncompressedSize;
            } 
            set
            { 
                Invariant.Assert((value >= 0), "UncompressedSize must be non-negative"); 

                _uncompressedSize = value; 
            }
        }

 
        private bool TestMatch(UInt32 signature,
                                                UInt32 crc32FromCentralDir, 
                                                long compressedSizeFromCentralDir, 
                                                long uncompressedSizeFromCentralDir,
                                                UInt32 suspectSignature, 
                                                UInt32 suspectCrc32,
                                                UInt64 suspectCompressedSize,
                                                UInt64 suspectUncompressedSize)
        { 
            checked
            { 
                // Don't compare compressedSize and uncompressedSize as long since the sniffed 
                //  bytes might not be the actual match and can be bigger than Int64.MaxValue
                //  Convert them as long only if it is a match 
                if  ((signature == suspectSignature) &&
                     ((UInt64) compressedSizeFromCentralDir == suspectCompressedSize) &&
                     ((UInt64) uncompressedSizeFromCentralDir == suspectUncompressedSize) &&
                     (crc32FromCentralDir == suspectCrc32)) 
                {
                    _signature = suspectSignature; 
                    _compressedSize = (long) suspectCompressedSize; 
                    _uncompressedSize = (long) suspectUncompressedSize;
                    _crc32 = suspectCrc32; 
                    return true;
                }
                else
                { 
                    return false;
                } 
            } 
        }
 
        private  const UInt32 _signatureConstant  = 0x08074b50;
        private const int _fixedMinimalRecordSizeWithoutSignature = 12;
        private const int _fixedMinimalRecordSizeWithSignature = 16;
        private const int _fixedMinimalRecordSizeWithoutSignatureZip64 = 20; 
        private const int _fixedMinimalRecordSizeWithSignatureZip64 = 24;
 
        private int _size; 

        private UInt32 _signature = _signatureConstant; 
        private UInt32 _crc32;
        private long _compressedSize = 0;
        private long _uncompressedSize = 0;
 
    }
} 

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

Network programming in C#, Network Programming in VB.NET, Network Programming in .NET
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
ZipIOLocalFileDataDescriptor.cs source code in C# .NET

Source code for the .NET framework in C#

Code:

Link Menu
