tarheader.cs

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// TarHeader.cs
//
// Copyright (C) 2001 Mike Krueger
//
// 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.


/* The tar format and its POSIX successor PAX have a long history which makes for compatability
   issues when creating and reading files.
   
   This is further complicated by a large number of programs with variations on formats
   One common issue is the handling of names longer than 100 characters.
   GNU style long names are currently supported.

This is the ustar (Posix 1003.1) header.

struct header 
{
	char t_name[100];          //   0 Filename
	char t_mode[8];            // 100 Permissions
	char t_uid[8];             // 108 Numerical User ID
	char t_gid[8];             // 116 Numerical Group ID
	char t_size[12];           // 124 Filesize
	char t_mtime[12];          // 136 st_mtime
	char t_chksum[8];          // 148 Checksum
	char t_typeflag;           // 156 Type of File
	char t_linkname[100];      // 157 Target of Links
	char t_magic[6];           // 257 "ustar" or other...
	char t_version[2];         // 263 Version fixed to 00
	char t_uname[32];          // 265 User Name
	char t_gname[32];          // 297 Group Name
	char t_devmajor[8];        // 329 Major for devices
	char t_devminor[8];        // 337 Minor for devices
	char t_prefix[155];        // 345 Prefix for t_name
	char t_mfill[12];          // 500 Filler up to 512
};

*/

using System;
using System.Text;

namespace ICSharpCode.SharpZipLib.Tar 
{
	
	
	/// <summary>
	/// This class encapsulates the Tar Entry Header used in Tar Archives.
	/// The class also holds a number of tar constants, used mostly in headers.
	/// </summary>
	public class TarHeader : ICloneable
	{
		/// <summary>
		/// The length of the name field in a header buffer.
		/// </summary>
		public readonly static int NAMELEN = 100;
		
		/// <summary>
		/// The length of the mode field in a header buffer.
		/// </summary>
		public readonly static int MODELEN = 8;
		
		/// <summary>
		/// The length of the user id field in a header buffer.
		/// </summary>
		public readonly static int UIDLEN = 8;
		
		/// <summary>
		/// The length of the group id field in a header buffer.
		/// </summary>
		public readonly static int GIDLEN = 8;
		
		/// <summary>
		/// The length of the checksum field in a header buffer.
		/// </summary>
		public readonly static int CHKSUMLEN = 8;

		/// <summary>
		/// Offset of checksum in a header buffer.
		/// </summary>
		public const int CHKSUMOFS = 148;
		
		/// <summary>
		/// The length of the size field in a header buffer.
		/// </summary>
		public readonly static int SIZELEN = 12;
		
		/// <summary>
		/// The length of the magic field in a header buffer.
		/// </summary>
		public readonly static int MAGICLEN = 6;
		
		/// <summary>
		/// The length of the version field in a header buffer.
		/// </summary>
		public readonly static int VERSIONLEN = 2;

		/// <summary>
		/// The length of the modification time field in a header buffer.
		/// </summary>
		public readonly static int MODTIMELEN = 12;
		
		/// <summary>
		/// The length of the user name field in a header buffer.
		/// </summary>
		public readonly static int UNAMELEN = 32;
		
		/// <summary>
		/// The length of the group name field in a header buffer.
		/// </summary>
		public readonly static int GNAMELEN = 32;
		
		/// <summary>
		/// The length of the devices field in a header buffer.
		/// </summary>
		public readonly static int DEVLEN = 8;
		
		//
		// LF_ constants represent the "type" of an entry
		//

		/// <summary>
		///  The "old way" of indicating a normal file.
		/// </summary>
		public const byte	LF_OLDNORM	= 0;
		
		/// <summary>
		/// Normal file type.
		/// </summary>
		public const byte	LF_NORMAL	= (byte) '0';
		
		/// <summary>
		/// Link file type.
		/// </summary>
		public const byte	LF_LINK		= (byte) '1';
		
		/// <summary>
		/// Symbolic link file type.
		/// </summary>
		public const byte	LF_SYMLINK	= (byte) '2';
		
		/// <summary>
		/// Character device file type.
		/// </summary>
		public const byte	LF_CHR		= (byte) '3';
		
		/// <summary>
		/// Block device file type.
		/// </summary>
		public const byte	LF_BLK		= (byte) '4';
		
		/// <summary>
		/// Directory file type.
		/// </summary>
		public const byte	LF_DIR		= (byte) '5';
		
		/// <summary>
		/// FIFO (pipe) file type.
		/// </summary>
		public const byte	LF_FIFO		= (byte) '6';
		
		/// <summary>
		/// Contiguous file type.
		/// </summary>
		public const byte	LF_CONTIG	= (byte) '7';
		
		/// <summary>
		/// Posix.1 2001 global extended header
		/// </summary>
		public const byte   LF_GHDR    = (byte) 'g';
		
		/// <summary>
		/// Posix.1 2001 extended header
		/// </summary>
		public readonly static byte   LF_XHDR    = (byte) 'x';
		
		
		
		
		// POSIX allows for upper case ascii type as extensions
		
		/// <summary>
		/// Solaris access control list file type
		/// </summary>
		public const byte   LF_ACL            = (byte) 'A';
		
		/// <summary>
		/// GNU dir dump file type
		/// This is a dir entry that contains the names of files that were in the
		/// dir at the time the dump was made
		/// </summary>
		public const byte   LF_GNU_DUMPDIR    = (byte) 'D';
		
		/// <summary>
		/// Solaris Extended Attribute File
		/// </summary>
		public const byte   LF_EXTATTR        = (byte) 'E' ;
		
		/// <summary>
		/// Inode (metadata only) no file content
		/// </summary>
		public const byte   LF_META           = (byte) 'I';
		
		/// <summary>
		/// Identifies the next file on the tape as having a long link name
		/// </summary>
		public const byte   LF_GNU_LONGLINK   = (byte) 'K';
		
		/// <summary>
		/// Identifies the next file on the tape as having a long name
		/// </summary>
		public const byte   LF_GNU_LONGNAME   = (byte) 'L';
		
		/// <summary>
		/// Continuation of a file that began on another volume
		/// </summary>
		public const byte   LF_GNU_MULTIVOL   = (byte) 'M';
		
		/// <summary>
		/// For storing filenames that dont fit in the main header (old GNU)
		/// </summary>
		public const byte   LF_GNU_NAMES      = (byte) 'N';
		
		/// <summary>
		/// GNU Sparse file
		/// </summary>
		public const byte   LF_GNU_SPARSE     = (byte) 'S';
		
		/// <summary>
		/// GNU Tape/volume header ignore on extraction
		/// </summary>
		public const byte   LF_GNU_VOLHDR     = (byte) 'V';
		
		/// <summary>
		/// The magic tag representing a POSIX tar archive.  (includes trailing NULL)
		/// </summary>
		public readonly static string	TMAGIC		= "ustar ";
		
		/// <summary>
		/// The magic tag representing an old GNU tar archive where version is included in magic and overwrites it
		/// </summary>
		public readonly static string	GNU_TMAGIC	= "ustar  ";
		

		string name;

		/// <summary>
		/// Get/set the name for this tar entry.
		/// </summary>
		/// <exception cref="ArgumentNullException">Thrown when attempting to set the property to null.</exception>
		public string Name
		{
			get { return name; }
			set { 
				if ( value == null ) {
					throw new ArgumentNullException();
				}
				name = value;	
			}
		}
		
		int mode;
		
		/// <summary>
		/// Get/set the entry's Unix style permission mode.
		/// </summary>
		public int Mode
		{
			get { return mode; }
			set { mode = value; }
		}
		
		int userId;
		
		/// <summary>
		/// The entry's user id.
		/// </summary>
		/// <remarks>
		/// This is only directly relevant to unix systems.
		/// The default is zero.
		/// </remarks>
		public int UserId
		{
			get { return userId; }
			set { userId = value; }
		}
		
		int groupId;
		
		/// <summary>
		/// Get/set the entry's group id.
		/// </summary>
		/// <remarks>
		/// This is only directly relevant to linux/unix systems.
		/// The default value is zero.
		/// </remarks>
		public int GroupId
		{
			get { return groupId; }
			set { groupId = value; }
		}
		

		long size;
		
		/// <summary>
		/// Get/set the entry's size.
		/// </summary>
		/// <exception cref="ArgumentOutOfRangeException">Thrown when setting the size to less than zero.</exception>
		public long Size
		{
			get { return size; }
			set { 
				if ( value < 0 ) {
					throw new ArgumentOutOfRangeException();
				}
				size = value; 
			}
		}
		
		DateTime modTime;
		
		/// <summary>
		/// Get/set the entry's modification time.
		/// </summary>
		/// <remarks>
		/// The modification time is only accurate to within a second.
		/// </remarks>
		/// <exception cref="ArgumentOutOfRangeException">Thrown when setting the date time to less than 1/1/1970.</exception>
		public DateTime ModTime
		{
			get { return modTime; }
			set {
				if ( value < dateTime1970 )
				{