/Utilities/Compression/ZipConstants.cs

// Based on Mike Krueger's SharpZipLib, Copyright (C) 2001 (GNU license).

// Authors of the original java version: Jochen Hoenicke, John Leuner

// See http://www.ISeeSharpCode.com for more information.



using System.Text;



namespace Delta.Utilities.Compression

{

	/// <summary>

	/// This class contains constants used for Zip format files

	/// </summary>

	public sealed class ZipConstants

	{

		#region Constants

		/// <summary>

		/// The version made by field for entries in the central header when

		/// created by this library

		/// </summary>

		/// <remarks>

		/// This is also the Zip version for the library when comparing against

		/// the version required to extract for an entry. See

		/// <see cref="Streams.ZipInputStream.CanDecompressEntry">

		/// ZipInputStream.CanDecompressEntry</see>.

		/// </remarks>

		public const int VersionMadeBy = 20;



		/// <summary>

		/// The minimum version required to support strong encryption

		/// </summary>

		public const int VersionStrongEncryption = 50;



		// The local entry header



		/// <summary>

		/// Size of local entry header (excluding variable length fields at end)

		/// </summary>

		public const int LocalHeader = 30;



		/// <summary>

		/// Signature for local entry header

		/// </summary>

		public const int LocalSignature = 'P' | ('K' << 8) | (3 << 16) | (4 << 24);



		/// <summary>

		/// Offset of version to extract in local entry header

		/// </summary>		

		public const int LocalVersion = 4;



		/// <summary>

		/// Offset of general purpose flags in local entry header

		/// </summary>

		public const int LocalFlag = 6;



		/// <summary>

		/// Offset of compression method in local entry header

		/// </summary>

		public const int LocalHow = 8;



		/// <summary>

		/// Offset of last mod file time + date in local entry header

		/// </summary>

		public const int LocalTime = 10;



		/// <summary>

		/// Offset of crc-32 in local entry header

		/// </summary>

		public const int LocalCrc = 14;



		/// <summary>

		/// Offset of compressed size in local entry header

		/// </summary>

		public const int LocalSize = 18;



		/// <summary>

		/// Offset of uncompressed size in local entry header

		/// </summary>

		public const int LocalLength = 22;



		/// <summary>

		/// Offset of file name length in local entry header

		/// </summary>

		public const int LocalName = 26;



		/// <summary>

		/// Offset of extra field length in local entry header

		/// </summary>

		public const int LocalExtension = 28;



		/// <summary>

		/// Signature for spanning entry

		/// </summary>

		public const int SpanningSig =

			'P' | ('K' << 8) | (7 << 16) | (8 << 24);



		/// <summary>

		/// Signature for temporary spanning entry

		/// </summary>

		public const int SpanningTempSig =

			'P' | ('K' << 8) | ('0' << 16) | ('0' << 24);



		/// <summary>

		/// Signature for data descriptor

		/// </summary>

		/// <remarks>

		/// This is only used where the length, Crc, or compressed size isn't

		/// known when the entry is created and the output stream doesnt support

		/// seeking. The local entry cannot be 'patched' with the correct values

		/// in this case so the values are recorded after the data prefixed by

		/// this header, as well as in the central directory.

		/// </remarks>

		public const int ExternSig =

			'P' | ('K' << 8) | (7 << 16) | (8 << 24);



		/// <summary>

		/// Size of data descriptor

		/// </summary>

		public const int ExternHeader = 16;



		/// <summary>

		/// Offset of crc-32 in data descriptor

		/// </summary>

		public const int ExternCrc = 4;



		/// <summary>

		/// Offset of compressed size in data descriptor

		/// </summary>

		public const int ExternSize = 8;



		/// <summary>

		/// Offset of uncompressed length in data descriptor

		/// </summary>

		public const int ExternLength = 12;



		/// <summary>

		/// Signature for central header

		/// </summary>

		public const int CentralDirectorySig =

			'P' | ('K' << 8) | (1 << 16) | (2 << 24);



		/// <summary>

		/// Signature for Zip64 central file header

		/// </summary>

		public const int CentralDirectorySig64 =

			'P' | ('K' << 8) | (6 << 16) | (6 << 24);



		/// <summary>

		/// Central header digitial signature

		/// </summary>

		public const int CentralDigitalSig =

			'P' | ('K' << 8) | (5 << 16) | (5 << 24);



		/// <summary>

		/// Size of central header entry

		/// </summary>

		public const int CentralHeader = 46;



		/// <summary>

		/// Offset of version made by in central file header

		/// </summary>

		public const int CentralVem = 4;



		/// <summary>

		/// Offset of version needed to extract in central file header

		/// </summary>

		public const int CentralVersion = 6;



		/// <summary>

		/// Offset of general purpose bit flag in central file header

		/// </summary>

		public const int CentralFlag = 8;



		/// <summary>

		/// Offset of compression method in central file header

		/// </summary>

		public const int CentralHow = 10;



		/// <summary>

		/// Offset of time/date in central file header

		/// </summary>

		public const int CentralTime = 12;



		/// <summary>

		/// Offset of crc-32 in central file header

		/// </summary>

		public const int CentralCrc = 16;



		/// <summary>

		/// Offset of compressed size in central file header

		/// </summary>

		public const int CentralSize = 20;



		/// <summary>

		/// Offset of uncompressed size in central file header

		/// </summary>

		public const int CentralLength = 24;



		/// <summary>

		/// Offset of file name length in central file header

		/// </summary>

		public const int CentralName = 28;



		/// <summary>

		/// Offset of extra field length in central file header

		/// </summary>

		public const int CentralExtension = 30;



		/// <summary>

		/// Offset of file comment length in central file header

		/// </summary>

		public const int CentralComment = 32;



		/// <summary>

		/// Offset of disk start number in central file header

		/// </summary>

		public const int CentralDiskStartNumber = 34;



		/// <summary>

		/// Offset of internal file attributes in central file header

		/// </summary>

		public const int CentralAttributes = 36;



		/// <summary>

		/// Offset of external file attributes in central file header

		/// </summary>

		public const int CentralExternalAttributes = 38;



		/// <summary>

		/// Offset of relative offset of local header in central file header

		/// </summary>

		public const int CentralOffset = 42;



		// The entries at the end of central directory



		/// <summary>

		/// End of central directory record signature

		/// </summary>

		public const int EndSig =

			'P' | ('K' << 8) | (5 << 16) | (6 << 24);



		/// <summary>

		/// Size of end of central record (excluding variable fields)

		/// </summary>

		public const int EndHeader = 22;



		// The following two fields are missing in SUN JDK



		/// <summary>

		/// Offset of number of this disk

		/// </summary>

		public const int EndNumberOfDisk = 4;



		/// <summary>

		/// Offset of number of disk with start of central directory

		/// </summary>

		public const int EndNumberOfDiskCentralDirectory = 6;



		/// <summary>

		/// Offset of number of entries in the central directory of this disk

		/// </summary>

		public const int EndEntriesInCentralDirectory = 8;



		/// <summary>

		/// Offset of total number of entries in the central directory

		/// </summary>

		public const int EndTotalNumberOfEntriesInCentralDirectory = 10;



		/// <summary>

		/// Offset of size of central directory

		/// </summary>

		public const int EndSizeOfCentralDirectory = 12;



		/// <summary>

		/// Offset of offset of start of central directory with respect to

		/// starting disk number

		/// </summary>

		public const int EndOffset = 16;



		/// <summary>

		/// Offset of ZIP file comment length

		/// </summary>

		public const int EndComment = 20;



		/// <summary>

		/// Size of cryptographic header stored before entry data

		/// </summary>

		public const int CryptoHeaderSize = 12;

		#endregion



		#region Public

		#endregion



		#region Convert methods

		/// <summary>

		/// Convert a portion of a byte array to a string.

		/// </summary>		

		/// <param name="data">

		/// Data to convert to string

		/// </param>

		/// <param name="length">

		/// Number of bytes to convert starting from index 0

		/// </param>

		/// <returns>

		/// data[0]..data[length - 1] converted to a string

		/// </returns>

		public static string ConvertToString(byte[] data, int length)

		{

			return Encoding.ASCII.GetString(data, 0, length);

		}



		/// <summary>

		/// Convert byte array to string

		/// </summary>

		/// <param name="data">

		/// Byte array to convert

		/// </param>

		/// <returns>

		/// <paramref name="data">data</paramref>converted to a string

		/// </returns>

		public static string ConvertToString(byte[] data)

		{

			return ConvertToString(data, data.Length);

		}

		#endregion

	}

}