| // | 
| // ZipExtraData.cs | 
| // | 
| // Copyright 2004-2007 John Reilly | 
| // | 
| // This program is free software; you can redistribute it and/or | 
| // modify it under the terms of the GNU General Public License | 
| // as published by the Free Software Foundation; either version 2 | 
| // of the License, or (at your option) any later version. | 
| // | 
| // This program is distributed in the hope that it will be useful, | 
| // but WITHOUT ANY WARRANTY; without even the implied warranty of | 
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the | 
| // GNU General Public License for more details. | 
| // | 
| // You should have received a copy of the GNU General Public License | 
| // along with this program; if not, write to the Free Software | 
| // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. | 
| // | 
| // Linking this library statically or dynamically with other modules is | 
| // making a combined work based on this library.  Thus, the terms and | 
| // conditions of the GNU General Public License cover the whole | 
| // combination. | 
| //  | 
| // As a special exception, the copyright holders of this library give you | 
| // permission to link this library with independent modules to produce an | 
| // executable, regardless of the license terms of these independent | 
| // modules, and to copy and distribute the resulting executable under | 
| // terms of your choice, provided that you also meet, for each linked | 
| // independent module, the terms and conditions of the license of that | 
| // module.  An independent module is a module which is not derived from | 
| // or based on this library.  If you modify this library, you may extend | 
| // this exception to your version of the library, but you are not | 
| // obligated to do so.  If you do not wish to do so, delete this | 
| // exception statement from your version. | 
|   | 
| using System; | 
| using System.IO; | 
|   | 
| namespace ICSharpCode.SharpZipLib.Zip | 
| { | 
|     // TODO: Sort out wether tagged data is useful and what a good implementation might look like. | 
|     // Its just a sketch of an idea at the moment. | 
|      | 
|     /// <summary> | 
|     /// ExtraData tagged value interface. | 
|     /// </summary> | 
|     public interface ITaggedData | 
|     { | 
|         /// <summary> | 
|         /// Get the ID for this tagged data value. | 
|         /// </summary> | 
|         short TagID { get; } | 
|   | 
|         /// <summary> | 
|         /// Set the contents of this instance from the data passed. | 
|         /// </summary> | 
|         /// <param name="data">The data to extract contents from.</param> | 
|         /// <param name="offset">The offset to begin extracting data from.</param> | 
|         /// <param name="count">The number of bytes to extract.</param> | 
|         void SetData(byte[] data, int offset, int count); | 
|   | 
|         /// <summary> | 
|         /// Get the data representing this instance. | 
|         /// </summary> | 
|         /// <returns>Returns the data for this instance.</returns> | 
|         byte[] GetData(); | 
|     } | 
|      | 
|     /// <summary> | 
|     /// A raw binary tagged value | 
|     /// </summary> | 
|     public class RawTaggedData : ITaggedData | 
|     { | 
|         /// <summary> | 
|         /// Initialise a new instance. | 
|         /// </summary> | 
|         /// <param name="tag">The tag ID.</param> | 
|         public RawTaggedData(short tag) | 
|         { | 
|             _tag = tag; | 
|         } | 
|   | 
|         #region ITaggedData Members | 
|   | 
|         /// <summary> | 
|         /// Get the ID for this tagged data value. | 
|         /// </summary> | 
|         public short TagID  | 
|         {  | 
|             get { return _tag; } | 
|             set { _tag = value; } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Set the data from the raw values provided. | 
|         /// </summary> | 
|         /// <param name="data">The raw data to extract values from.</param> | 
|         /// <param name="offset">The index to start extracting values from.</param> | 
|         /// <param name="count">The number of bytes available.</param> | 
|         public void SetData(byte[] data, int offset, int count) | 
|         { | 
|             if( data==null ) | 
|             { | 
|                 throw new ArgumentNullException("data"); | 
|             } | 
|   | 
|             _data=new byte[count]; | 
|             Array.Copy(data, offset, _data, 0, count); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get the binary data representing this instance. | 
|         /// </summary> | 
|         /// <returns>The raw binary data representing this instance.</returns> | 
|         public byte[] GetData() | 
|         { | 
|             return _data; | 
|         } | 
|   | 
|         #endregion | 
|   | 
|         /// <summary> | 
|         /// Get /set the binary data representing this instance. | 
|         /// </summary> | 
|         /// <returns>The raw binary data representing this instance.</returns> | 
|         public byte[] Data | 
|         { | 
|             get { return _data; } | 
|             set { _data=value; } | 
|         } | 
|   | 
|         #region Instance Fields | 
|         /// <summary> | 
|         /// The tag ID for this instance. | 
|         /// </summary> | 
|         short _tag; | 
|   | 
|         byte[] _data; | 
|         #endregion | 
|     } | 
|   | 
|     /// <summary> | 
|     /// Class representing extended unix date time values. | 
|     /// </summary> | 
|     public class ExtendedUnixData : ITaggedData | 
|     { | 
|         /// <summary> | 
|         /// Flags indicate which values are included in this instance. | 
|         /// </summary> | 
|         [Flags] | 
|         public enum Flags : byte | 
|         { | 
|             /// <summary> | 
|             /// The modification time is included | 
|             /// </summary> | 
|             ModificationTime = 0x01, | 
|              | 
|             /// <summary> | 
|             /// The access time is included | 
|             /// </summary> | 
|             AccessTime = 0x02, | 
|              | 
|             /// <summary> | 
|             /// The create time is included. | 
|             /// </summary> | 
|             CreateTime = 0x04, | 
|         } | 
|          | 
|         #region ITaggedData Members | 
|   | 
|         /// <summary> | 
|         /// Get the ID | 
|         /// </summary> | 
|         public short TagID | 
|         {  | 
|             get { return 0x5455; } | 
|         } | 
|          | 
|         /// <summary> | 
|         /// Set the data from the raw values provided. | 
|         /// </summary> | 
|         /// <param name="data">The raw data to extract values from.</param> | 
|         /// <param name="index">The index to start extracting values from.</param> | 
|         /// <param name="count">The number of bytes available.</param> | 
|         public void SetData(byte[] data, int index, int count) | 
|         { | 
|             using (MemoryStream ms = new MemoryStream(data, index, count, false)) | 
|             using (ZipHelperStream helperStream = new ZipHelperStream(ms)) | 
|             { | 
|                 // bit 0           if set, modification time is present | 
|                 // bit 1           if set, access time is present | 
|                 // bit 2           if set, creation time is present | 
|                  | 
|                 _flags = (Flags)helperStream.ReadByte(); | 
|                 if (((_flags & Flags.ModificationTime) != 0) && (count >= 5)) | 
|                 { | 
|                     int iTime = helperStream.ReadLEInt(); | 
|   | 
|                     _modificationTime = (new DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime() + | 
|                         new TimeSpan(0, 0, 0, iTime, 0)).ToLocalTime(); | 
|                 } | 
|   | 
|                 if ((_flags & Flags.AccessTime) != 0) | 
|                 { | 
|                     int iTime = helperStream.ReadLEInt(); | 
|   | 
|                     _lastAccessTime = (new DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime() + | 
|                         new TimeSpan(0, 0, 0, iTime, 0)).ToLocalTime(); | 
|                 } | 
|                  | 
|                 if ((_flags & Flags.CreateTime) != 0) | 
|                 { | 
|                     int iTime = helperStream.ReadLEInt(); | 
|   | 
|                     _createTime = (new DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime() + | 
|                         new TimeSpan(0, 0, 0, iTime, 0)).ToLocalTime(); | 
|                 } | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get the binary data representing this instance. | 
|         /// </summary> | 
|         /// <returns>The raw binary data representing this instance.</returns> | 
|         public byte[] GetData() | 
|         { | 
|             using (MemoryStream ms = new MemoryStream()) | 
|             using (ZipHelperStream helperStream = new ZipHelperStream(ms)) | 
|             { | 
|                 helperStream.IsStreamOwner = false; | 
|                 helperStream.WriteByte((byte)_flags);     // Flags | 
|                 if ( (_flags & Flags.ModificationTime) != 0) { | 
|                     TimeSpan span = _modificationTime.ToUniversalTime() - new DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime(); | 
|                     int seconds = (int)span.TotalSeconds; | 
|                     helperStream.WriteLEInt(seconds); | 
|                 } | 
|                 if ( (_flags & Flags.AccessTime) != 0) { | 
|                     TimeSpan span = _lastAccessTime.ToUniversalTime() - new DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime(); | 
|                     int seconds = (int)span.TotalSeconds; | 
|                     helperStream.WriteLEInt(seconds); | 
|                 } | 
|                 if ( (_flags & Flags.CreateTime) != 0) { | 
|                     TimeSpan span = _createTime.ToUniversalTime() - new DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime(); | 
|                     int seconds = (int)span.TotalSeconds; | 
|                     helperStream.WriteLEInt(seconds); | 
|                 } | 
|                 return ms.ToArray(); | 
|             } | 
|         } | 
|   | 
|         #endregion | 
|   | 
|         /// <summary> | 
|         /// Test a <see cref="DateTime"> value to see if is valid and can be represented here.</see> | 
|         /// </summary> | 
|         /// <param name="value">The <see cref="DateTime">value</see> to test.</param> | 
|         /// <returns>Returns true if the value is valid and can be represented; false if not.</returns> | 
|         /// <remarks>The standard Unix time is a signed integer data type, directly encoding the Unix time number, | 
|         /// which is the number of seconds since 1970-01-01. | 
|         /// Being 32 bits means the values here cover a range of about 136 years. | 
|         /// The minimum representable time is 1901-12-13 20:45:52, | 
|         /// and the maximum representable time is 2038-01-19 03:14:07. | 
|         /// </remarks> | 
|         public static bool IsValidValue(DateTime value) | 
|         { | 
|             return (( value >= new DateTime(1901, 12, 13, 20, 45, 52)) ||  | 
|                     ( value <= new DateTime(2038, 1, 19, 03, 14, 07) )); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get /set the Modification Time | 
|         /// </summary> | 
|         /// <exception cref="ArgumentOutOfRangeException"></exception> | 
|         /// <seealso cref="IsValidValue"></seealso> | 
|         public DateTime ModificationTime | 
|         { | 
|             get { return _modificationTime; } | 
|             set | 
|             { | 
|                 if ( !IsValidValue(value) ) { | 
|                     throw new ArgumentOutOfRangeException("value"); | 
|                 } | 
|                  | 
|                 _flags |= Flags.ModificationTime; | 
|                 _modificationTime=value; | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get / set the Access Time | 
|         /// </summary> | 
|         /// <exception cref="ArgumentOutOfRangeException"></exception> | 
|         /// <seealso cref="IsValidValue"></seealso> | 
|         public DateTime AccessTime | 
|         { | 
|             get { return _lastAccessTime; } | 
|             set {  | 
|                 if ( !IsValidValue(value) ) { | 
|                     throw new ArgumentOutOfRangeException("value"); | 
|                 } | 
|              | 
|                 _flags |= Flags.AccessTime; | 
|                 _lastAccessTime=value;  | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get / Set the Create Time | 
|         /// </summary> | 
|         /// <exception cref="ArgumentOutOfRangeException"></exception> | 
|         /// <seealso cref="IsValidValue"></seealso> | 
|         public DateTime CreateTime | 
|         { | 
|             get { return _createTime; } | 
|             set { | 
|                 if ( !IsValidValue(value) ) { | 
|                     throw new ArgumentOutOfRangeException("value"); | 
|                 } | 
|              | 
|                 _flags |= Flags.CreateTime; | 
|                 _createTime=value; | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get/set the <see cref="Flags">values</see> to include. | 
|         /// </summary> | 
|         Flags Include | 
|         { | 
|             get { return _flags; } | 
|             set { _flags = value; } | 
|         } | 
|   | 
|         #region Instance Fields | 
|         Flags _flags; | 
|         DateTime _modificationTime = new DateTime(1970,1,1); | 
|         DateTime _lastAccessTime = new DateTime(1970, 1, 1); | 
|         DateTime _createTime = new DateTime(1970, 1, 1); | 
|         #endregion | 
|     } | 
|   | 
|     /// <summary> | 
|     /// Class handling NT date time values. | 
|     /// </summary> | 
|     public class NTTaggedData : ITaggedData | 
|     { | 
|         /// <summary> | 
|         /// Get the ID for this tagged data value. | 
|         /// </summary> | 
|         public short TagID | 
|         {  | 
|             get { return 10; } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Set the data from the raw values provided. | 
|         /// </summary> | 
|         /// <param name="data">The raw data to extract values from.</param> | 
|         /// <param name="index">The index to start extracting values from.</param> | 
|         /// <param name="count">The number of bytes available.</param> | 
|         public void SetData(byte[] data, int index, int count) | 
|         { | 
|             using (MemoryStream ms = new MemoryStream(data, index, count, false))  | 
|             using (ZipHelperStream helperStream = new ZipHelperStream(ms)) | 
|             { | 
|                 helperStream.ReadLEInt(); // Reserved | 
|                 while (helperStream.Position < helperStream.Length) | 
|                 { | 
|                     int ntfsTag = helperStream.ReadLEShort(); | 
|                     int ntfsLength = helperStream.ReadLEShort(); | 
|                     if (ntfsTag == 1) | 
|                     { | 
|                         if (ntfsLength >= 24) | 
|                         { | 
|                             long lastModificationTicks = helperStream.ReadLELong(); | 
|                             _lastModificationTime = DateTime.FromFileTime(lastModificationTicks); | 
|   | 
|                             long lastAccessTicks = helperStream.ReadLELong(); | 
|                             _lastAccessTime = DateTime.FromFileTime(lastAccessTicks); | 
|   | 
|                             long createTimeTicks = helperStream.ReadLELong(); | 
|                             _createTime = DateTime.FromFileTime(createTimeTicks); | 
|                         } | 
|                         break; | 
|                     } | 
|                     else | 
|                     { | 
|                         // An unknown NTFS tag so simply skip it. | 
|                         helperStream.Seek(ntfsLength, SeekOrigin.Current); | 
|                     } | 
|                 } | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get the binary data representing this instance. | 
|         /// </summary> | 
|         /// <returns>The raw binary data representing this instance.</returns> | 
|         public byte[] GetData() | 
|         { | 
|             using (MemoryStream ms = new MemoryStream()) | 
|             using (ZipHelperStream helperStream = new ZipHelperStream(ms)) | 
|             { | 
|                 helperStream.IsStreamOwner = false; | 
|                 helperStream.WriteLEInt(0);       // Reserved | 
|                 helperStream.WriteLEShort(1);     // Tag | 
|                 helperStream.WriteLEShort(24);    // Length = 3 x 8. | 
|                 helperStream.WriteLELong(_lastModificationTime.ToFileTime()); | 
|                 helperStream.WriteLELong(_lastAccessTime.ToFileTime()); | 
|                 helperStream.WriteLELong(_createTime.ToFileTime()); | 
|                 return ms.ToArray(); | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Test a <see cref="DateTime"> valuie to see if is valid and can be represented here.</see> | 
|         /// </summary> | 
|         /// <param name="value">The <see cref="DateTime">value</see> to test.</param> | 
|         /// <returns>Returns true if the value is valid and can be represented; false if not.</returns> | 
|         /// <remarks> | 
|         /// NTFS filetimes are 64-bit unsigned integers, stored in Intel | 
|         /// (least significant byte first) byte order. They determine the | 
|         /// number of 1.0E-07 seconds (1/10th microseconds!) past WinNT "epoch", | 
|         /// which is "01-Jan-1601 00:00:00 UTC". 28 May 60056 is the upper limit | 
|         /// </remarks> | 
|         public static bool IsValidValue(DateTime value) | 
|         { | 
|             bool result = true; | 
|             try | 
|             { | 
|                 value.ToFileTimeUtc(); | 
|             } | 
|             catch | 
|             { | 
|                 result = false; | 
|             } | 
|             return result; | 
|         } | 
|          | 
|         /// <summary> | 
|         /// Get/set the <see cref="DateTime">last modification time</see>. | 
|         /// </summary> | 
|         public DateTime LastModificationTime | 
|         { | 
|             get { return _lastModificationTime; } | 
|             set { | 
|                 if (! IsValidValue(value)) | 
|                 { | 
|                     throw new ArgumentOutOfRangeException("value"); | 
|                 } | 
|                 _lastModificationTime = value; | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get /set the <see cref="DateTime">create time</see> | 
|         /// </summary> | 
|         public DateTime CreateTime | 
|         { | 
|             get { return _createTime; } | 
|             set { | 
|                 if ( !IsValidValue(value)) { | 
|                     throw new ArgumentOutOfRangeException("value"); | 
|                 } | 
|                 _createTime = value; | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get /set the <see cref="DateTime">last access time</see>. | 
|         /// </summary> | 
|         public DateTime LastAccessTime | 
|         { | 
|             get { return _lastAccessTime; } | 
|             set { | 
|                 if (!IsValidValue(value)) { | 
|                     throw new ArgumentOutOfRangeException("value"); | 
|                 } | 
|                 _lastAccessTime = value;  | 
|             } | 
|         } | 
|   | 
|         #region Instance Fields | 
|         DateTime _lastAccessTime = DateTime.FromFileTime(0); | 
|         DateTime _lastModificationTime = DateTime.FromFileTime(0); | 
|         DateTime _createTime = DateTime.FromFileTime(0); | 
|         #endregion | 
|     } | 
|   | 
|     /// <summary> | 
|     /// A factory that creates <see cref="ITaggedData">tagged data</see> instances. | 
|     /// </summary> | 
|     interface ITaggedDataFactory | 
|     { | 
|         /// <summary> | 
|         /// Get data for a specific tag value. | 
|         /// </summary> | 
|         /// <param name="tag">The tag ID to find.</param> | 
|         /// <param name="data">The data to search.</param> | 
|         /// <param name="offset">The offset to begin extracting data from.</param> | 
|         /// <param name="count">The number of bytes to extract.</param> | 
|         /// <returns>The located <see cref="ITaggedData">value found</see>, or null if not found.</returns> | 
|         ITaggedData Create(short tag, byte[] data, int offset, int count); | 
|     } | 
|   | 
|     ///  | 
|     /// <summary> | 
|     /// A class to handle the extra data field for Zip entries | 
|     /// </summary> | 
|     /// <remarks> | 
|     /// Extra data contains 0 or more values each prefixed by a header tag and length. | 
|     /// They contain zero or more bytes of actual data. | 
|     /// The data is held internally using a copy on write strategy.  This is more efficient but | 
|     /// means that for extra data created by passing in data can have the values modified by the caller | 
|     /// in some circumstances. | 
|     /// </remarks> | 
|     sealed public class ZipExtraData : IDisposable | 
|     { | 
|         #region Constructors | 
|         /// <summary> | 
|         /// Initialise a default instance. | 
|         /// </summary> | 
|         public ZipExtraData() | 
|         { | 
|             Clear(); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Initialise with known extra data. | 
|         /// </summary> | 
|         /// <param name="data">The extra data.</param> | 
|         public ZipExtraData(byte[] data) | 
|         { | 
|             if ( data == null ) | 
|             { | 
|                 _data = new byte[0]; | 
|             } | 
|             else | 
|             { | 
|                 _data = data; | 
|             } | 
|         } | 
|         #endregion | 
|   | 
|         /// <summary> | 
|         /// Get the raw extra data value | 
|         /// </summary> | 
|         /// <returns>Returns the raw byte[] extra data this instance represents.</returns> | 
|         public byte[] GetEntryData() | 
|         { | 
|             if ( Length > ushort.MaxValue ) { | 
|                 throw new ZipException("Data exceeds maximum length"); | 
|             } | 
|   | 
|             return (byte[])_data.Clone(); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Clear the stored data. | 
|         /// </summary> | 
|         public void Clear() | 
|         { | 
|             if ( (_data == null) || (_data.Length != 0) ) { | 
|                 _data = new byte[0]; | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Gets the current extra data length. | 
|         /// </summary> | 
|         public int Length | 
|         { | 
|             get { return _data.Length; } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get a read-only <see cref="Stream"/> for the associated tag. | 
|         /// </summary> | 
|         /// <param name="tag">The tag to locate data for.</param> | 
|         /// <returns>Returns a <see cref="Stream"/> containing tag data or null if no tag was found.</returns> | 
|         public Stream GetStreamForTag(int tag) | 
|         { | 
|             Stream result = null; | 
|             if ( Find(tag) ) { | 
|                 result = new MemoryStream(_data, _index, _readValueLength, false); | 
|             } | 
|             return result; | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get the <see cref="ITaggedData">tagged data</see> for a tag. | 
|         /// </summary> | 
|         /// <param name="tag">The tag to search for.</param> | 
|         /// <returns>Returns a <see cref="ITaggedData">tagged value</see> or null if none found.</returns> | 
|         private ITaggedData GetData(short tag) | 
|         { | 
|             ITaggedData result = null; | 
|             if (Find(tag)) | 
|             { | 
|                 result = Create(tag, _data, _readValueStart, _readValueLength); | 
|             } | 
|             return result; | 
|         } | 
|   | 
|         static ITaggedData Create(short tag, byte[] data, int offset, int count) | 
|         { | 
|             ITaggedData result = null; | 
|             switch ( tag ) | 
|             { | 
|                 case 0x000A: | 
|                     result = new NTTaggedData(); | 
|                     break; | 
|                 case 0x5455: | 
|                     result = new ExtendedUnixData(); | 
|                     break; | 
|                 default: | 
|                     result = new RawTaggedData(tag); | 
|                     break; | 
|             } | 
|             result.SetData(data, offset, count); | 
|             return result; | 
|         } | 
|          | 
|         /// <summary> | 
|         /// Get the length of the last value found by <see cref="Find"/> | 
|         /// </summary> | 
|         /// <remarks>This is only valid if <see cref="Find"/> has previously returned true.</remarks> | 
|         public int ValueLength | 
|         { | 
|             get { return _readValueLength; } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get the index for the current read value. | 
|         /// </summary> | 
|         /// <remarks>This is only valid if <see cref="Find"/> has previously returned true. | 
|         /// Initially the result will be the index of the first byte of actual data.  The value is updated after calls to | 
|         /// <see cref="ReadInt"/>, <see cref="ReadShort"/> and <see cref="ReadLong"/>. </remarks> | 
|         public int CurrentReadIndex | 
|         { | 
|             get { return _index; } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Get the number of bytes remaining to be read for the current value; | 
|         /// </summary> | 
|         public int UnreadCount | 
|         { | 
|             get  | 
|             { | 
|                 if ((_readValueStart > _data.Length) || | 
|                     (_readValueStart < 4) ) { | 
|                     throw new ZipException("Find must be called before calling a Read method"); | 
|                 } | 
|   | 
|                 return _readValueStart + _readValueLength - _index;  | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Find an extra data value | 
|         /// </summary> | 
|         /// <param name="headerID">The identifier for the value to find.</param> | 
|         /// <returns>Returns true if the value was found; false otherwise.</returns> | 
|         public bool Find(int headerID) | 
|         { | 
|             _readValueStart = _data.Length; | 
|             _readValueLength = 0; | 
|             _index = 0; | 
|   | 
|             int localLength = _readValueStart; | 
|             int localTag = headerID - 1; | 
|   | 
|             // Trailing bytes that cant make up an entry (as there arent enough | 
|             // bytes for a tag and length) are ignored! | 
|             while ( (localTag != headerID) && (_index < _data.Length - 3) ) { | 
|                 localTag = ReadShortInternal(); | 
|                 localLength = ReadShortInternal(); | 
|                 if ( localTag != headerID ) { | 
|                     _index += localLength; | 
|                 } | 
|             } | 
|   | 
|             bool result = (localTag == headerID) && ((_index + localLength) <= _data.Length); | 
|   | 
|             if ( result ) { | 
|                 _readValueStart = _index; | 
|                 _readValueLength = localLength; | 
|             } | 
|   | 
|             return result; | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add a new entry to extra data. | 
|         /// </summary> | 
|         /// <param name="taggedData">The <see cref="ITaggedData"/> value to add.</param> | 
|         public void AddEntry(ITaggedData taggedData) | 
|         { | 
|             if (taggedData == null) | 
|             { | 
|                 throw new ArgumentNullException("taggedData"); | 
|             } | 
|             AddEntry(taggedData.TagID, taggedData.GetData()); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add a new entry to extra data | 
|         /// </summary> | 
|         /// <param name="headerID">The ID for this entry.</param> | 
|         /// <param name="fieldData">The data to add.</param> | 
|         /// <remarks>If the ID already exists its contents are replaced.</remarks> | 
|         public void AddEntry(int headerID, byte[] fieldData) | 
|         { | 
|             if ( (headerID > ushort.MaxValue) || (headerID < 0)) { | 
|                 throw new ArgumentOutOfRangeException("headerID"); | 
|             } | 
|   | 
|             int addLength = (fieldData == null) ? 0 : fieldData.Length; | 
|   | 
|             if ( addLength > ushort.MaxValue ) { | 
| #if NETCF_1_0 | 
|                 throw new ArgumentOutOfRangeException("fieldData"); | 
| #else | 
|                 throw new ArgumentOutOfRangeException("fieldData", "exceeds maximum length"); | 
| #endif | 
|             } | 
|   | 
|             // Test for new length before adjusting data. | 
|             int newLength = _data.Length + addLength + 4; | 
|   | 
|             if ( Find(headerID) ) | 
|             { | 
|                 newLength -= (ValueLength + 4); | 
|             } | 
|   | 
|             if ( newLength > ushort.MaxValue ) { | 
|                 throw new ZipException("Data exceeds maximum length"); | 
|             } | 
|              | 
|             Delete(headerID); | 
|   | 
|             byte[] newData = new byte[newLength]; | 
|             _data.CopyTo(newData, 0); | 
|             int index = _data.Length; | 
|             _data = newData; | 
|             SetShort(ref index, headerID); | 
|             SetShort(ref index, addLength); | 
|             if ( fieldData != null ) { | 
|                 fieldData.CopyTo(newData, index); | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Start adding a new entry. | 
|         /// </summary> | 
|         /// <remarks>Add data using <see cref="AddData(byte[])"/>, <see cref="AddLeShort"/>, <see cref="AddLeInt"/>, or <see cref="AddLeLong"/>. | 
|         /// The new entry is completed and actually added by calling <see cref="AddNewEntry"/></remarks> | 
|         /// <seealso cref="AddEntry(ITaggedData)"/> | 
|         public void StartNewEntry() | 
|         { | 
|             _newEntry = new MemoryStream(); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add entry data added since <see cref="StartNewEntry"/> using the ID passed. | 
|         /// </summary> | 
|         /// <param name="headerID">The identifier to use for this entry.</param> | 
|         public void AddNewEntry(int headerID) | 
|         { | 
|             byte[] newData = _newEntry.ToArray(); | 
|             _newEntry = null; | 
|             AddEntry(headerID, newData); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add a byte of data to the pending new entry. | 
|         /// </summary> | 
|         /// <param name="data">The byte to add.</param> | 
|         /// <seealso cref="StartNewEntry"/> | 
|         public void AddData(byte data) | 
|         { | 
|             _newEntry.WriteByte(data); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add data to a pending new entry. | 
|         /// </summary> | 
|         /// <param name="data">The data to add.</param> | 
|         /// <seealso cref="StartNewEntry"/> | 
|         public void AddData(byte[] data) | 
|         { | 
|             if ( data == null ) { | 
|                 throw new ArgumentNullException("data"); | 
|             } | 
|   | 
|             _newEntry.Write(data, 0, data.Length); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add a short value in little endian order to the pending new entry. | 
|         /// </summary> | 
|         /// <param name="toAdd">The data to add.</param> | 
|         /// <seealso cref="StartNewEntry"/> | 
|         public void AddLeShort(int toAdd) | 
|         { | 
|             unchecked { | 
|                 _newEntry.WriteByte(( byte )toAdd); | 
|                 _newEntry.WriteByte(( byte )(toAdd >> 8)); | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add an integer value in little endian order to the pending new entry. | 
|         /// </summary> | 
|         /// <param name="toAdd">The data to add.</param> | 
|         /// <seealso cref="StartNewEntry"/> | 
|         public void AddLeInt(int toAdd) | 
|         { | 
|             unchecked { | 
|                 AddLeShort(( short )toAdd); | 
|                 AddLeShort(( short )(toAdd >> 16)); | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Add a long value in little endian order to the pending new entry. | 
|         /// </summary> | 
|         /// <param name="toAdd">The data to add.</param> | 
|         /// <seealso cref="StartNewEntry"/> | 
|         public void AddLeLong(long toAdd) | 
|         { | 
|             unchecked { | 
|                 AddLeInt(( int )(toAdd & 0xffffffff)); | 
|                 AddLeInt(( int )(toAdd >> 32)); | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Delete an extra data field. | 
|         /// </summary> | 
|         /// <param name="headerID">The identifier of the field to delete.</param> | 
|         /// <returns>Returns true if the field was found and deleted.</returns> | 
|         public bool Delete(int headerID) | 
|         { | 
|             bool result = false; | 
|   | 
|             if ( Find(headerID) ) { | 
|                 result = true; | 
|                 int trueStart = _readValueStart - 4; | 
|   | 
|                 byte[] newData = new byte[_data.Length - (ValueLength + 4)]; | 
|                 Array.Copy(_data, 0, newData, 0, trueStart); | 
|   | 
|                 int trueEnd = trueStart + ValueLength + 4; | 
|                 Array.Copy(_data, trueEnd, newData, trueStart, _data.Length - trueEnd); | 
|                 _data = newData; | 
|             } | 
|             return result; | 
|         } | 
|   | 
|         #region Reading Support | 
|         /// <summary> | 
|         /// Read a long in little endian form from the last <see cref="Find">found</see> data value | 
|         /// </summary> | 
|         /// <returns>Returns the long value read.</returns> | 
|         public long ReadLong() | 
|         { | 
|             ReadCheck(8); | 
|             return (ReadInt() & 0xffffffff) | ((( long )ReadInt()) << 32); | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Read an integer in little endian form from the last <see cref="Find">found</see> data value. | 
|         /// </summary> | 
|         /// <returns>Returns the integer read.</returns> | 
|         public int ReadInt() | 
|         { | 
|             ReadCheck(4); | 
|   | 
|             int result = _data[_index] + (_data[_index + 1] << 8) +  | 
|                 (_data[_index + 2] << 16) + (_data[_index + 3] << 24); | 
|             _index += 4; | 
|             return result; | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Read a short value in little endian form from the last <see cref="Find">found</see> data value. | 
|         /// </summary> | 
|         /// <returns>Returns the short value read.</returns> | 
|         public int ReadShort() | 
|         { | 
|             ReadCheck(2); | 
|             int result = _data[_index] + (_data[_index + 1] << 8); | 
|             _index += 2; | 
|             return result; | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Read a byte from an extra data | 
|         /// </summary> | 
|         /// <returns>The byte value read or -1 if the end of data has been reached.</returns> | 
|         public int ReadByte() | 
|         { | 
|             int result = -1; | 
|             if ( (_index < _data.Length) && (_readValueStart + _readValueLength > _index) ) { | 
|                 result = _data[_index]; | 
|                 _index += 1; | 
|             } | 
|             return result; | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Skip data during reading. | 
|         /// </summary> | 
|         /// <param name="amount">The number of bytes to skip.</param> | 
|         public void Skip(int amount) | 
|         { | 
|             ReadCheck(amount); | 
|             _index += amount; | 
|         } | 
|   | 
|         void ReadCheck(int length) | 
|         { | 
|             if ((_readValueStart > _data.Length) || | 
|                 (_readValueStart < 4) ) { | 
|                 throw new ZipException("Find must be called before calling a Read method"); | 
|             } | 
|   | 
|             if (_index > _readValueStart + _readValueLength - length ) { | 
|                 throw new ZipException("End of extra data"); | 
|             } | 
|   | 
|             if ( _index + length < 4 ) { | 
|                 throw new ZipException("Cannot read before start of tag"); | 
|             } | 
|         } | 
|   | 
|         /// <summary> | 
|         /// Internal form of <see cref="ReadShort"/> that reads data at any location. | 
|         /// </summary> | 
|         /// <returns>Returns the short value read.</returns> | 
|         int ReadShortInternal() | 
|         { | 
|             if ( _index > _data.Length - 2) { | 
|                 throw new ZipException("End of extra data"); | 
|             } | 
|   | 
|             int result = _data[_index] + (_data[_index + 1] << 8); | 
|             _index += 2; | 
|             return result; | 
|         } | 
|   | 
|         void SetShort(ref int index, int source) | 
|         { | 
|             _data[index] = (byte)source; | 
|             _data[index + 1] = (byte)(source >> 8); | 
|             index += 2; | 
|         } | 
|   | 
|         #endregion | 
|   | 
|         #region IDisposable Members | 
|   | 
|         /// <summary> | 
|         /// Dispose of this instance. | 
|         /// </summary> | 
|         public void Dispose() | 
|         { | 
|             if ( _newEntry != null ) { | 
|                 _newEntry.Close(); | 
|             } | 
|         } | 
|   | 
|         #endregion | 
|   | 
|         #region Instance Fields | 
|         int _index; | 
|         int _readValueStart; | 
|         int _readValueLength; | 
|   | 
|         MemoryStream _newEntry; | 
|         byte[] _data; | 
|         #endregion | 
|     } | 
| } |