opensim – Rev 1
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/*
* Copyright (c) Contributors, http://opensimulator.org/
* See CONTRIBUTORS.TXT for a full list of copyright holders.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the OpenSimulator Project nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
using System;
using System.IO;
using System.Reflection;
using System.Text;
using log4net;
namespace OpenSim.Framework.Serialization
{
/// <summary>
/// Temporary code to do the bare minimum required to read a tar archive for our purposes
/// </summary>
public class TarArchiveReader
{
//private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
public enum TarEntryType
{
TYPE_UNKNOWN = 0,
TYPE_NORMAL_FILE = 1,
TYPE_HARD_LINK = 2,
TYPE_SYMBOLIC_LINK = 3,
TYPE_CHAR_SPECIAL = 4,
TYPE_BLOCK_SPECIAL = 5,
TYPE_DIRECTORY = 6,
TYPE_FIFO = 7,
TYPE_CONTIGUOUS_FILE = 8,
}
/// <summary>
/// Binary reader for the underlying stream
/// </summary>
protected BinaryReader m_br;
/// <summary>
/// Used to trim off null chars
/// </summary>
protected static char[] m_nullCharArray = new char[] { '\0' };
/// <summary>
/// Used to trim off space chars
/// </summary>
protected static char[] m_spaceCharArray = new char[] { ' ' };
/// <summary>
/// Generate a tar reader which reads from the given stream.
/// </summary>
/// <param name="s"></param>
public TarArchiveReader(Stream s)
{
m_br = new BinaryReader(s);
}
/// <summary>
/// Read the next entry in the tar file.
/// </summary>
/// <param name="filePath"></param>
/// <returns>the data for the entry. Returns null if there are no more entries</returns>
public byte[] ReadEntry(out string filePath, out TarEntryType entryType)
{
filePath = String.Empty;
entryType = TarEntryType.TYPE_UNKNOWN;
TarHeader header = ReadHeader();
if (null == header)
return null;
entryType = header.EntryType;
filePath = header.FilePath;
return ReadData(header.FileSize);
}
/// <summary>
/// Read the next 512 byte chunk of data as a tar header.
/// </summary>
/// <returns>A tar header struct. null if we have reached the end of the archive.</returns>
protected TarHeader ReadHeader()
{
byte[] header = m_br.ReadBytes(512);
// If there are no more bytes in the stream, return null header
if (header.Length == 0)
return null;
// If we've reached the end of the archive we'll be in null block territory, which means
// the next byte will be 0
if (header[0] == 0)
return null;
TarHeader tarHeader = new TarHeader();
// If we're looking at a GNU tar long link then extract the long name and pull up the next header
if (header[156] == (byte)'L')
{
int longNameLength = ConvertOctalBytesToDecimal(header, 124, 11);
tarHeader.FilePath = Encoding.ASCII.GetString(ReadData(longNameLength));
//m_log.DebugFormat("[TAR ARCHIVE READER]: Got long file name {0}", tarHeader.FilePath);
header = m_br.ReadBytes(512);
}
else
{
tarHeader.FilePath = Encoding.ASCII.GetString(header, 0, 100);
tarHeader.FilePath = tarHeader.FilePath.Trim(m_nullCharArray);
//m_log.DebugFormat("[TAR ARCHIVE READER]: Got short file name {0}", tarHeader.FilePath);
}
tarHeader.FileSize = ConvertOctalBytesToDecimal(header, 124, 11);
switch (header[156])
{
case 0:
tarHeader.EntryType = TarEntryType.TYPE_NORMAL_FILE;
break;
case (byte)'0':
tarHeader.EntryType = TarEntryType.TYPE_NORMAL_FILE;
break;
case (byte)'1':
tarHeader.EntryType = TarEntryType.TYPE_HARD_LINK;
break;
case (byte)'2':
tarHeader.EntryType = TarEntryType.TYPE_SYMBOLIC_LINK;
break;
case (byte)'3':
tarHeader.EntryType = TarEntryType.TYPE_CHAR_SPECIAL;
break;
case (byte)'4':
tarHeader.EntryType = TarEntryType.TYPE_BLOCK_SPECIAL;
break;
case (byte)'5':
tarHeader.EntryType = TarEntryType.TYPE_DIRECTORY;
break;
case (byte)'6':
tarHeader.EntryType = TarEntryType.TYPE_FIFO;
break;
case (byte)'7':
tarHeader.EntryType = TarEntryType.TYPE_CONTIGUOUS_FILE;
break;
}
return tarHeader;
}
/// <summary>
/// Read data following a header
/// </summary>
/// <param name="fileSize"></param>
/// <returns></returns>
protected byte[] ReadData(int fileSize)
{
byte[] data = m_br.ReadBytes(fileSize);
//m_log.DebugFormat("[TAR ARCHIVE READER]: fileSize {0}", fileSize);
// Read the rest of the empty padding in the 512 byte block
if (fileSize % 512 != 0)
{
int paddingLeft = 512 - (fileSize % 512);
//m_log.DebugFormat("[TAR ARCHIVE READER]: Reading {0} padding bytes", paddingLeft);
m_br.ReadBytes(paddingLeft);
}
return data;
}
public void Close()
{
m_br.Close();
}
/// <summary>
/// Convert octal bytes to a decimal representation
/// </summary>
/// <param name="bytes"></param>
/// <returns></returns>
public static int ConvertOctalBytesToDecimal(byte[] bytes, int startIndex, int count)
{
// Trim leading white space: ancient tars do that instead
// of leading 0s :-( don't ask. really.
string oString = Encoding.ASCII.GetString(bytes, startIndex, count).TrimStart(m_spaceCharArray);
int d = 0;
foreach (char c in oString)
{
d <<= 3;
d |= c - '0';
}
return d;
}
}
public class TarHeader
{
public string FilePath;
public int FileSize;
public TarArchiveReader.TarEntryType EntryType;
}
}